Nirma Phase 2

PHASE - II

LINEAR ALKYL BENZENE (LAB)

Table of contents List of figures ............................................................................................................................. i List of Tables .......................................................................................................................... iii Abbreviations .......................................................................................................................... iv Nomenclature .......................................................................................................................... vi CHAPTER 1: INTRODUCTION TO PRODUCT .............................................................. 1 1.1 History .............................................................................................................................. 2 1.2 Details of LAB Capacity .................................................................................................. 3 1.3 Market value of LAB ....................................................................................................... 3 1.4 Competitors ...................................................................................................................... 3 1.5 Technology provider ........................................................................................................ 3 1.6 Application ....................................................................................................................... 3 1.7 Physical, Chemical properties of LAB ............................................................................. 4 CHAPTER 2: SELECTION OF PROCESS ......................................................................... 5 Introduction ............................................................................................................................ 6 2.1 Raw Material Specifications ............................................................................................ 6 2.1.1 Availability & Transportation of Raw Material ........................................................ 6 2.1.2 Cost of raw materials ................................................................................................. 6 Properties of raw materials ................................................................................................. 6 2.2 Discussion on alternative technologies for the production of LAB ................................. 9 2.3 Selection of technology .................................................................................................. 10 2.4 Overview of the process ................................................................................................. 10 2.4.2 Block diagram of Process ........................................................................................ 11 2.4.3 Process description .................................................................................................. 11 CHAPTER 3: MATERIAL BALAN.................................................................................... 49 3.1 INTRODUCTION .......................................................................................................... 50 3.2 Overall Material Balance ............................................................................................... 50 3.3 BLOCK DIAGRAM OF OVERALL M.B .................................................................... 81 CHAPTER 4: ENERGY BALANCE ................................................................................... 82 4.1 INTRODUCTION .......................................................................................................... 83 CHAPTER 5: UTILITIES .................................................................................................. 109 5.1 Hydrogen Plant ............................................................................................................. 110 5.2 Nitrogen plant............................................................................................................... 113

5.3 Hot Oil Heater .............................................................................................................. 114 5.4 Cooling tower ............................................................................................................... 116 5.5 D.M.Water plant ........................................................................................................... 117 5.6 Boiler ............................................................................................................................ 119 5.7 Flare system.................................................................................................................. 120 5.8 Instrument Air .............................................................................................................. 121 5.9 Tank Farm .................................................................................................................... 121 5.10 Pump house ................................................................................................................ 123 5.11 Loading-Unloading .................................................................................................... 124 CHAPTER 6: DETAILED DESCRIPTION OF EQUIPMENTS................................... 125 CHAPTER 7: EQUIPMENT DESIGN .............................................................................. 130 7.1 Stripper Column Design ............................................................................................... 131 7.2 Heat Exchanger ............................................................................................................ 136 CHAPTER 8: PUMPS & CONTROL VALVE ................................................................ 148 8.1 Introduction .................................................................................................................. 149 CHAPTER: 9 FIRE, SAFETY AND POLLUTION ......................................................... 154 9.1 Introduction to Safety ................................................................................................... 155 9.1.1 Safety equipments used in plant are: ..................................................................... 155 9.1.2 The safety measures taken in the tanks are: .......................................................... 156 9.1.3 The safety measures taken in case of fire are: ....................................................... 156 9.1.4 Fire hazards: .......................................................................................................... 156 9.1.5 Principle of protection & prevention: .................................................................... 158 9.2 Pollution Control .......................................................................................................... 159 9.2.1 Effluent Treatment Plant ....................................................................................... 159 9.2.2 Process flow diagram............................................................................................. 160 9.2.3 Process flow description ........................................................................................ 160 CHAPTER 10: PLANT LOCATION & PLANT LAYOUT ........................................... 163 10.1 Plant location .............................................................................................................. 164 10.2 Plant layout ................................................................................................................. 165 CHAPTER 11: COST ESTIMATION ............................................................................... 169 11.1Introduction ................................................................................................................. 170 CHAPTER 12: CONCLUSION.......................................................................................... 179 13: REFERENCES .............................................................................................................. 181

Acknowledgement ................................................................................................................ 182

List of figures Pg no Figure 1.1

Chemical structure of LAB

03

Figure 2.4.1

Process block diagram

11

Figure 2.4.2

Stripper column

12

Figure 2.4.3

Rerun column

12

Figure 2.4.4

Nitrogen removal

15

Figure 2.4.5

Halide removal

16

Figure 2.4.6

Union fining reactor

17

Figure 2.4.7

Product stripper column

17

Figure 2.4.8

Light end stripper

18

Figure 2.4.9

Molex feed

23

Figure 2.4.10

Moving bed system

24

Figure 2.4.11

Adsorption chamber

26

Figure 2.4.12

Extract column

27

Figure 2.4.13

Desorbent stripper column

27

Figure 2.4.14

Raffinate column

28

Figure 2.4.15

Pacol reactor

33

Figure 2.4.16

Product stripper

34

Figure 2.4.17

Define reactor

39

Figure 2.4.18

Pep adsorption system

40

Figure 2.4.19

Desorbent column

41

Figure 2.4.20

Depentanizer column

41

Figure 2.4.21

Detal reactors

44

Figure 2.4.22

Benzene column

45

Figure 2.4.23

Paraffin column

45

Figure 2.4.24

Rerun column

46

Figure 2.4.25

Recycle column

46

Figure 3.1

Block Dia. Of Overall M.B.

81

Figure 5.1

Process flow diagram of H2 Plant

110

i

Figure 5.3

Process flow diagram of Hot oil heater

115

Figure 5.4

Diagram of cooling tower

116

Figure 5.5

Process flow diagram of D.M water plant

117

Figure 5.6

Boiler process block diagram

119

Figure 8.1

Cascade control

151

Figure 8.2

Ratio Control

152

Figure 9.1

Process flow dia. Of ETP

159

Figure 10.1

Outside battery limit of plant

165

Figure 10.2

Inside battery limit of plant

166

ii

List of Tables

Pg no Table 1.1

Physical & Chemical Properties of LAB

4

Table 2.2.1

Properties of Kerosene

6

Table 2.2.2

Properties of n-Pentane

7

Table 2.2.3

Properties of iso-octane

8

Table 2.2.4

Properties of Benzene

8

Table 2.2.5

Properties of Hydrogen

9

Table 2.4.1

Contents of hydrotreater catalyst

15

Table 2.4.2

Suction and discharge pressure for MUG compressor

21

Table 2.4.3

Contents of Molex adsorbent

22

Table 2.4.4

Contents of Pacol catalyst

33

Table 2.4.5

Data of Pacol CFE inlet-outlet temperature

36

Table 2.4.6

Contents of Define catalyst

38

Table 3.1

Overall material balance for frontend

63

Table 3.2

Overall material balance of backend

80

Table 3.3

Overall material balance of Plant

81

Table 4.1

Energy balance summary table

107

Table 5.1

Water specification for D.M water plant

118

Table 5.2

Data of Steam production

119

Table 5.3

Data of Steam consumption

120

Table 5.4

Data of Water specification for boiler

120

Table 5.5

Data of storage Tank and its capacity

122

Table 5.6

Data of Pump type and its capacity

123

Table 5.7

Data of unloading point for raw material

124

Table 9.1

Fire extinguishers

157

Table 9.2

Data of Final treated quality of ETP

160

Table 10.1

Color coding of plant

167

iii

Abbreviations LAB

Linear alkyl benzene

HAB

Heavy alkyl benzene

PF

Pre-fractionation

UF

Union fining

MOLEX

Molecular extraction

TNP

Total normal paraffin

TNN

Total non normal paraffin

PACOL

Paraffin converted to olefin

PEP

Pacol enhancement process

DETAL

Detergent Alkylation

HO

Hot oil

MUG

Make up gas compressor

HOH

Hot oil heater

ETP

Effluent treatment plant

LPFD

Low pressure feed drum

HPS

High pressure separator

DSD

Desorbent surge drum

CMI

Coplanar manifold index

KSC

Kilogram per square centimeter

LES

Light end stripper

iv

FFC

Fin fan cooler

SWS

Sour water stream

UOP

Universal oil product

EMD

Extract mixing drum

RMD

Raffinate mixing drum

v

Nomenclature

Symbol

Full Form

SI Unit

Cp

Specific heat

kJ/kg k



Latent heat of vaporization

kJ/kg

M

Mass flow rate

Kg/hr

Q

Heat flow rate

kJ/hr

Eo

Overall tray efficiency

V

Vapor flow rate

m3/hr

Vc

Column velocity

m/s

D

Diameter

M

A

Area

m2

Ρ

Density

Kg/m3

Co

Orifice co-efficient

Vo

Hole velocity

m/s

H

Height

M

P

Pressure

KPa

T

Temperature

C

Μ

Viscosity

Kg/ms

E

Efficiency

T

Thickness

Mm

vi

tr`

Roof plate thickness

Mm

vii

CHAPTER 1: INTRODUCTION TO PRODUCT

1

1.1 History In 1939, the soap industry began to create detergents using surfactants that were supplied to the soap manufacturers by the petro-chemical industry. Because the synthetic detergents produced from these surfactants were a substantial improvement over soap products in use at the time, they soon gave rise to a global synthetic detergent industry. In late 1940s, UOP developed a process to economically produce commercial quantities of Do-Decyl Benzene Sulphonates (DDBS), which became one of the surfactants most widely used in synthetic detergents at that time. In the late 1950s, it was found that DDBS had a slow rate of biodegradation that resulted in generation of large amounts of foam in surface waters, such as rivers and streams. UOP responded to the industry need for the more bio-degradable detergents by developing process technology in the 1960s to produce Linear Alkyl Benzene (LAB), a new surfactant raw material used to make Linear Alkyl Benzene Sulphonate (LAS). LAS were deemed to be a much more bio-degradable surfactant and to this day, they are one of the main building blocks in the manufacture of detergents. The popularity of LAB can be attributed to excellent LAS surfactant properties, it’s biodegradability, and it’s low cost of manufacture compared to other surfactant raw materials. Over the past several decades, worldwide demand for LAB has continued to grow. Linear alkyl benzene referred to as LAB is an intermediate in detergent production. The chemical structure of LAB is shown in figures below:

Figure 1.1 Chemical structure of LAB

IUPAC Name: Linear Alkyl Benzene

2

1.2 Details of LAB Capacity INDIA is one of the largest producer of LAB in the world. In Indian LAB market there are five major producers of LAB. Namely NIRMA (Savli), IOCL, RELIANCE, Tamilnadu Petro-Chemicals. India is reeling under the oversupply of LAB, as the domestic demand is lower than the domestic capacity and production. The total domestic demand is estimated at around 300000 TPA, while the production capacity is close to 500000 TPA. They are exporting their surplus to ensure higher capacity utilization. Reliance is the largest industry in the Indian LAB sector with the dominant share of the capacity amounting to 185000 TPA. RIL is also the 5th largest producer of LAB in the world. Tamilnadu petro-chemicals and IOCL have installed LAB capacity of 120000 TPA. And NIRMA located at Savli has the installed capacity of 75000 TPA. Overall capacity of LAB in the world is around 3.5 million TPA.

1.3 Market value of LAB Market value of LAB in the India is ranging from 78000 to 100000 Rs./tons

1.4 Competitors Technical Mainly all the LAB plants are prepared by the UOP (Universal Oil Product) – A Honeywell Company. But it has competition with BASF, DOU etc. Commercial Commercially IOCL, RIL, NIRMA & Tamilnadu Petro-Chemicals are major competitors.

1.5 Technology provider Technology provider for all the major LAB plants is UOP (Universal Oil Product) – A Honeywll Company.

1.6 Application  LAB is the most common raw material for the manufacture of bio-degradable household detergents. It is sulphonated to produce linear alkyl benzene sulphonate (LAS). 3

 2% Agricultural Herbicides  Emulsion polymerisation  Electrical cable oil  Wetting agent  Ink solvent  Paint industry

1.7 Physical, Chemical properties of LAB Table 1.1 Properties of LAB Property

Specification

Appearance

Clear colorless liquid

Odor

Odor less

Boiling Point

282 – 302 oC

Flash Point

130 oC

Aniline Point

15.9

Average Molecular Weight

235 – 239 Kg/Kmol

Specific Gravity at 20oC

0.855 – 0.870

Kinematic Viscosity at 40oC

4.3 centistokes

Vapor Pressure at 20oC

0.01mmHg

Bromine Index

10 max mg/100g

Moisture

200 max ppm

4

CHAPTER 2: SELECTION OF PROCESS

5

Introduction In this chapter we discussed about raw material specification, its suppliers, and properties of materials to be used, various routes by which the LAB product produced and final selection of the process which is most suitable for the . The commercial development of LAB focused on the extraction of high purity linear paraffin derived from kerosene feed. This linear paraffin was dehydrogenated to linear internal mono-olefins. Using a catalyst dehydrogenated effluent was used to alkylate benzene to produce LAB. The resulting LAB product became the detergent intermediate for the production of linear alkyl benzene sulfonate which is a major biodegradable synthetic surfactant which replaced do-decyl benzene having slow rates of biodegradation.

2.1 Raw Material Specifications 2.1.1 Availability & Transportation of Raw Material Mainly raw materials are supplied from 

Kerosene – IOCL (Pipe-line)



Benzene – Reliance (By road through tankers)



N-pentane – PPL, Oriented Ltd. (By road through tankers)



Fuel oil, Naphtha – HPCL, BPCL, IOCL (Pipe-line)



LPG – IOCL, HPCL, BPCL (Pipe-line)

2.1.2 Cost of raw materials 

Benzene - 55000 Rs./ton



N-paraffin – 75000 Rs./ton



Kerosene – 15000 Rs./ton

Properties of raw materials 2.1.1 Kerosene Table 2.1 Properties of Kerosene Formula

C7 to C17.

State

Liquid.

Color

Colorless to light yellow

6

Boiling Point Range

175-265 0C.

Specific Gravity

0.8

Smoke point

18 mm

Flammable

Yes.

Water Solubility

Very less.

Bromine index

2 max

Flash point

42C

2.1.2 n-Pentane Table 2.2 Properties of n-Pentane Formula

C5H12.

State

Liquid

Color

Colorless

Molecular weight

72.2Kg/Kmol

Boiling Point Range

360C

Specific Gravity

0.63

Flammable

Yes

Water Solubility

Partially soluble

Melting point

129.70C

Flash point

-35C

2.1.3 iso-octane 7

Table 2.3 Properties of iso-octane Formula

(CH3)3.CH2.CH.(CH3)2

State

Liquid

Color

Colorless

Molecular weight

119.2Kg/Kmol

Boiling Point Range

99.2 0C

Specific Gravity

0.692

Flammable

Yes

Water Solubility

Insoluble

Flash point

-10C

2.1.4 Benzene Table 2.4 Properties of Benzene Formula

C6H6

State

Liquid

Molecular weight

78 Kg/Kmol

Boiling Point Range

80 – 85 0C

Specific Gravity

0.87

Flammable

Yes

Water Solubility

Very less

Flash point

-11C

2.1.5 Hydrogen

8

Table 2.5 Properties of Hydrogen Appearance

Colorless

Odor

Odorless

Stability

Stable

Specific Gravity

0.069

Auto Ignition Temperature (oC)

570

Flammability

Flammable

2.2 Discussion on alternative technologies for the production of LAB There are five production processes of LAB [1] UOP/HF n-paraffin process: The HF process involving dehydrogenation of n-paraffin to olefins & subsequent reaction with benzene using HF as catalyst. These process accounts for the majority of the installed LAB production in the world, It includes a PACOL stage where n-paraffin are converted to monoolefins a Define unit whose primary function is to convert residual diolefin to mono-olefin a Pep unit and alkylation step where alkylation of benzene is done by reaction between benzene & paraffin by using HF acid as catalyst.

[2] UOP/Detal process: This is a newer technology & has several of stages same as in the HF process but it is principally different in the benzene alkylation step, during which a solid-state catalyst (AlSiF4) is employed.

[3] Friedel-craft alkylation: Friedel-craft involves chlorination of n-paraffin to mono chloro paraffin followed by benzene Alkylation with AlCl3 catalyst. This is the oldest process.

[4] HF /olefin process: Purchased olefins reacted with benzene in presence of HF or AlCl3 catalyst.

[5] Sasol process: 9

In this process chlorination of n-paraffin to mono-chlorinated paraffin followed by dechlorination to produce olefins & subsequent benzene alkylation.

2.3 Selection of technology Several LAB production processes are reviewed. The emphasis is on the Detal & HF processes as these are the dominant technologies in the LAB industry today. UOP HF process involve the problem of corrosion, catalyst neutralization, disposal of HF & environmental concerns while Detal technology is very safe, non-corrosive ,ecofriendly & zero discharge. Detal process uses solid catalyst which is re-generable over life of 2 years, so it is also economically viable. From the overall observations Detal process is preferred for LAB production.

2.4 Overview of the process The process plant is divided into two main sections. These two sections contain process units. [1] Front end  Pre-fractionation (PF)  Union fining (UF)  Molecular extraction (MOLEX) [2] Back end  Paraffin converted to olefin (Pacol)  Pacol Enhancement Process (Pep)  Di-olefins Conversion to Mono Olefins (Define)  Detergent Alkylation (Detal)

Kerosene Pre-fractionation is used to tailor the kerosene feed to the desired carbon range. Kerosene is stripped off light ends and heavier ends so that the heart cut, containing the desired n-paraffin for the production of LAB of a certain range of molecular weight is produced. The Distillate Union Fining process hydro treats kerosene at sufficient severity to remove sulphur, nitrogen, olefins, and oxygenates compounds which might poison the Molex adsorbent. The Molex process is a liquid state separation of n-paraffin from branched and cyclic components using Sorbex Technology. The simulated moving bed adsorptive separation results from using a proprietary multiport rotary valve. The extract stream is a high purity n-paraffin

10

stream. The raffinate stream, consist mainly of iso-kerosene or cyclic-kerosene range compounds.

In Pacol process, the n-paraffin is de-hydrogenated in a vapor phase reaction to produce corresponding mono-olefins over a highly selective and active catalyst. The Define process is a liquid phase selective hydrogenation of di-olefins in the Pacol reactor effluent to corresponding mono-olefins over a catalyst bed. The P.E.P process allows the selective removal of aromatics in the feed to the Detal. The Detal process is a solid catalyst fixed bed process in which benzene is alkylated with monoolefins produced in Pacol Unit to produce LAB

2.4.2 Block diagram of Process

Figure 2.4.2.1 Process block diagram

2.4.3 Process description A. Front end: 2.4.3.1 Pre-fractionation (PF) 2.4.3.1.1 Introduction LAB manufacturing requires special type of feed. To get this specification Prefractionation is used. The feed to the Pre-fractionation unit is straight run Kerosene, which contains carbon range C7 to C17. This stream contains considerably more nonlinear *hydrocarbon than linear hydrocarbon. Pre-fractionation section contains one stripper column 11

and one rerun column. The carbon range for LAB feed is from nC10 to nC13 for light LAB product and nC11 to nC14 for heavy LAB product. Stripper column removes lighter components up to C9 and rerun column removes C14 to C17 the heavier components. The product stream from rerun column is called “Heart-cut” which contain C10-C13 carbon range along with contaminants like organic sulphur, nitrogen & metal compounds.

2.4.3.1.2 Process flow diagram

Figure 2.4.1: Stripper column

Figure 2.4.2: Rerun column

2.4.3.1.3 Process flow description

12

Supply kerosene from the storage tank is pumped through fresh feed/rerun bottom exchanger where bottom exchanger pre-heats the feed to 910C & then to feed/rerun pump around exchanger where it is heated from 910C to1380C & fed to 26th tray of the stripper column. In the Stripper columns the lighter ends C7-C9 are stripped on temperature difference & removed from top. The heat load to the stripper column is supplied by thermo siphon type re-boiler & the heating medium used is circulating hot oil [Therminol]. The stripper column overhead vapours are condensed in fin fan cooler, where it is cooled from 158 °C to 770C. The condensed liquid is collected in receiver. Before the stripper overhead is send to fin fan cooler, water wash is given for dilution of the halide impurities which may corrode the fin pipes. From the receiver, the non-condensable goes to the flare header. The receiver floats on the flare header pressure, positive nitrogen pressure given as purge eliminates any possibility of back flow to the receiver which may lead to contamination. The condensed liquid in the receiver separates into water & kerosene. The sour water collects in the receiver boot and is send to Effluent Treatment Plant (ETP).One stream of the receiver liquid is sent as reflux to the column & the other stream is sent to return kerosene storage tanks. The bottom product from stripper column is pumped by stripper column bottom pump & fed to the 27th tray of the rerun column. This stream contains C10 & other heavier hydrocarbons and will be at about 236°C.This stream is sent to the rerun column. This column is provided with two re-boilers [one as stand by].Thermo siphon re-boiler supplies heat to the rerun column. The heating medium used is circulating hot oil [Therminol] & its flow is controlled by Flow Control Valve. This column is operated under vacuum & its vacuum is maintained by the vacuum pump. The overhead of rerun column is C10-C13 heart cut. The overhead vapours (O/H vapours) are condensed in built in packed bed contact condenser by the flow controlled cold reflux & collected in the O/H accumulator located below contact condenser. The temperature of the accumulator tray is around 159 °C. The rerun column O/H pumps take suction from the accumulator and delivers into three separate streams. The first stream is sent as hot reflux on the first tray controlled by Flow Control Valve (FCV), which is cascaded with TRC [41st tray temperature].The second stream is taken as a side stream, downstream of feed/rerun pump around exchanger routed through rerun pump around cooler cooled to 55°C and sent to the top of contact condenser as cold reflux controlled by FCV. The third stream is the feed to UF unit. It has a carbon range of C10-C13 hydrocarbons. The bottom products from the rerun column are pumped by rerun bottom pump to the kerosene tanks via feed/rerun bottom exchanger and return kerosene cooler. This stream will have carbon range of C14-C17 hydrocarbons. 13

2.4.3.1.4 Process equipments [1] Stripper column Stripper column consists of 50 trays. The feed enters on the 26th tray. It has a narrow cross sectional area at the top while it is broad from bottom. The input of heat is from bottom through horizontal Thermo-siphon type re-boiler. The heat input is the only independent variable which will affect the reflux rate and as a result the distillation efficiency of the column. The stripper bottom is pumped from column on level controller and sent directly to rerun column. [2] Rerun column The Rerun column consists of 50 trays. There is no separate storage tank on top but there is an inbuilt accumulator which stores the heart cut. Heat input to this column is provided by Hot Oil circulation to the Re-boiler. The Rerun column is operated under vacuum to minimize the required heat input. The vacuum conditions are maintained by a line from top of column to LRVP.

2.4.3.2 Union fining (UF) 2.4.3.2.1 Introduction Contaminants like Sulphur, Nitrogen and Metal compounds are present in the petroleum fraction. Purpose of Union fining process is to remove these contaminants as they lead to problems like increase in air pollution, corrosion & difficulties in further processing of material [damage the molecular sieves used in MOLEX]. Union fining is a catalytic, fixed bed process developed by UOP for hydro treating a wide range of feed stocks. This process uses a catalytic hydrogenation method to upgrade the quality of petroleum fractions by decomposing contaminants with negligible effect on the boiling range of the feed. This process removes sulphur & nitrogen & saturates olefin & aromatic compounds while reducing other contaminants like oxygenates & organ metallic compounds. The hydrogenation of feed is obtained by processing the feedstock over a fixed bed of catalyst in the presence of large amount of hydrogen. UNIONFINING is a fixed bed catalytic process in which “NIMOX” catalyst with alumina base is used for removal of these contaminants by hydro treating. After hydro treating reaction 0.2wt% sulphur & 0.02wt% nitrogen are permissible.

14

UF reactor catalyst: The Hydro treater catalyst consists of oxides of nickel and molybdenum impregnated on an alumina base. The catalyst is prepared either as a sphere or an extrudate with special shapes. The catalyst is yellowish green in colour and odourless. Table 2.4.1 Contents of Hydro treater Catalyst Content

Weight Percent

Aluminum Oxide

65 – 80

Molybdenum Trioxide

10 – 19

Phosphorus Oxide

02 – 08

Nickel Oxide

01 – 05

2.4.3.2.2 Hydro treating chemistry The following chemical steps and reactions occur during hydro treating process [1] Sulphur Removal Typical feed stocks of crude oil contain simple Mercaptans, Sulphides and Di-sulphides, which can be easily converted to Hydrogen Sulphide (H2S). Feed stocks containing heteroatom molecules difficult to process. De-sulphurization of heteroatom compounds proceeds as:  Initial ring opening.  Sulphur removal  Saturation of resulting olefin [2] Nitrogen removal De-Nitrogenation is more difficult than De-sulphurization. Side reactions may yield nitrogen compounds more difficult to hydrogenate than the original reactant. Saturation of heterocyclic rings is also hindered by large attached groups. The de-Nitrogenation of the heteroatom rings proceeds as:  Aromatic ring Saturation  Ring hydrogenolysis  De-Nitrogenation For example Quinoline

4

Fig 2.4.4: Nitrogen removal 15

[3] Oxygen Removal The organically combined oxygen is removed by hydrogenation of the carbon – hydroxyl bond forming water and the corresponding hydrocarbon. [4] Olefin Saturation The Olefin saturation reaction proceeds very rapidly. It has very high heat of reaction. a. Linear Olefin R-C=C-C-C-R’ + H2

R-C-C-C-C-R’ (and isomers)

[5] Aromatic Saturation Aromatic Saturation reactions are most difficult and are highly exothermic in nature. [6] Halides Removal Organic Halides such as chlorides and bromides are decomposed in the reactor. Decomposition of organic halides is considered difficult with a maximum removal of ~90%.

Fig 2.4.5: Halide removal [7] Metal Removal Crude Oil contains metals like nickel, vanadium, lead etc. Iron is also present, which is corrosion product. Sodium, Calcium and Magnesium are also present due to contact of feed with salt water or additives. Improper use of additives to protect stripper overhead systems from corrosion or to control foaming account for the presence of phosphorus and silicon. The mechanism of the decomposition of organ metallic compounds is not well understood. However, it is known that metals are retained on the catalyst by a combination of adsorption and chemical reaction. The catalyst has a certain maximum tolerance for retaining metals. Removal of metals normally occurs in plug flow fashion with respect to the catalyst bed. Metal removal is essentially complete above temperature of 315oC to a metals loading of 2 – 3 wt% of the total catalyst.

2.4.3.2.3 Process flow diagram

16

Figure 2.4.6: Union fining reactor

Figure 2.4.7: Product stripper column

17

Figure 2.4.8: Light end stripper

2.4.3.2.4 Process flow description Product from pre fraction unit is stored in the feed surge drum of union fining unit. By using sun dyne pump it is pumped to combined feed heat exchanger, here the temperature of feed is increases up to 2920C and again it is sent to charge heater for further increasing of temperature. Outlet of charge heater is at 3110C. The heat exchanger is known as combined feed heat exchanger because here H2 and feed both are heated with the outlet of catalytic bed reactor by using sun dyne pump the pressure is increases up to 75 – 80 kg/cm2. In the catalytic bed there are two beds provided. In the reactor hydrogenation reaction is carried out, & hydrogenation reactions are exothermic in nature. The reactor contains two beds to maintain temperature by providing quenching hydrogen in between the beds. In this catalytic bed reactor NIMOX catalyst is used. It is Nickel with Molybdenum oxide catalyst on alumina base. In the reactor, temperature and pressure requirement are high because for sulfur removal high temperature is required and for nitrogen removal high pressure is required. At the output of reactor water injection and hydrogen addition is carried out. Water injection is carried out in order to dissolve the (NH3)2S formed during the reaction. In the reactor the H2/ HC ratio is about 500 (volume basis), and the makeup gas depends upon the reaction conversion. 18

The makeup gas comes from MUG compressor’s 4th stage. By using number of compressors in

series the pressure is increases from 2 kg/cm2 to 80 kg/cm2.This outlet of

reactor goes to fin fan cooler and is send to high pressure separator. Here the pressure is reduced by upto7 kg/cm2. At the top of separator hydrogen is separated and that hydrogen is sent to recycle gas compressor. The liquid of high pressure separator is then sent to low pressure separator. The reduction of pressure is carried out by using angle valve. From low pressure separator the liquid is sent to product stripper column, and off gases are removed from the top. These off gases are used in Hot Oil Heater (H.O.H.) as a fuel. Over head of product stripper column is cooled in fin fan cooler and sent to receiver. From the boot of receiver the sour water is collected, which goes to STP plant. One fraction of liquid from receiver is recycled back to product stripper and the other fraction is sent to light end stripper column. The bottom of product stripper column is the final product of the Union fining unit which is feed for the MOLEX unit. The light end stripper column bottom is sent to return kerosene tank. This column is on the total reflux condition

2.4.3.2.5 Process Equipments [1] Reactor: A Kerosene Union Fining reactor is typically constructed of 1.25 Cr-0.25 Mo, 2.25 Cr–1 Mo base metals with S.S lining. The alloy is selected on excellent corrosion resistant properties. Reactor has two beds of catalysts with one inter bed quenching zone. The Reactor consists: 1. Inlet Diffuser It is inserted into the inlet nozzle to eliminate a symmetric flow pattern, reduce fluid velocity and distribute the liquid evenly across the tray. 2. Vapor/Liquid Distribution tray Optimum catalyst performance is achieved when efficient contact of reactant is provided. The tray is fabricated sections by beams and a ring on vessel wall. Cylindrical risers with slotted caps are evenly spaced across top of tray. 3. Quenched Section The reaction system is divided into multiple catalyst bed with each bed separated by quench section. The quench assembly is designed to thoroughly mix quench gas with effluent from previous bed and re-distribute the reactants uniformly over the top of next catalyst bed.

[2] Stripper column: 19

This is a vertical vessel constructed of carbon Steel. It is made up of number of sieve trays which will vary depending on units designed. Feed is introduced towards the middle of columns. The stripper is typically re-boiled with circulating Hot Oil. The stripper bottom is pumped out from bottom of column while vapor flows to overhead condenser. Liquid reflux is returned to top of column above tray number 1. [3] Light ends stripper column: The column is a vertical carbon steel vessel which is fitted with internals to support two packed beds for vapor liquid contact. [4] Charge heater: The Charge Heater of UF section is made up of S.S 34%. It produces the desired reaction temperature of 311°C. It consists of two sections (i) Radiation Section:

Consists of 28 vertical tubes. Feed passes through the tubes.

(ii) Convection Section: Consists of 18 horizontal tubes. Feed passed through the tubes where it is heated by convection currents of flue gases rising. The charge heater is single pass. The source of heat is 3 burners. Fuel Oil is used as fuel & reaction temperature of 311°C is obtained. [5] Sun dyne pump: Sun dyne pump is also called vertical pump, it is used for high flow and high pressure. Here we need high pressure to keep the kerosene in liquid phase. It consists of one main shaft which is coupled with motor which rotates at 30000 rpm. There are two gears, one having small grooves fixed with other having large grooves. Again this large gear is grooved with small. The arrangement is such that one revolution of large gear produces 3-4 revolutions of smaller grooves. The pump produces a discharge pressure of 117 kg/cm2 .It is high speed pump with 20600 rpm. [6] Recycle gas compressor: It is constructed of killed carbon steel with 316 SS mesh blanket for entrained liquid removal located towards top of the reactor. Gas enters side of vessel and leaves out from the top and condensed liquid is drained periodically from bottom. It is single stage double acting compressor. There are two pistons and two cylinders for continuous discharge. H2 gas from HPS goes to cooler. Thus liquid particles get separated and gas then goes to separator. It has a mesh blanket. The suction pressure of R.G compressor is 68kg/cm2 and discharge pressure is 78 kg/cm2.

20

[7] Make up gas compressor: It is constructed of killed carbon steel. It is four stage single acting compressor. The suction and discharge pressure of the four stages are:

Table 2.4.2 Suction & Discharge pressure for MUG compressor Suction pressure

Discharge pressure

1st Stage

1.8

7

2nd Stage

7

18

3rd Stage

18

39

4th Stage

39

80

The H2 gas feed to this compressor is from PACOL unit. If PACOL unit is closed H2 gas is added to the third stage from hydrogen plant. The first two stages run on spill back. Thus it increases pressure from 1.8 kg/cm2 to 80 kg/cm2.

2.4.3.3 Molecular extraction (Molex) 2.4.3.3.1 Introduction Molex stands for Molecular Extraction. The product of Union Fining has a mixture of Normal (Linear) and Non-normal (Branched) Paraffin. They have almost the same boiling point. The UOP MOLEX Process is an effective method of continuously separating Normal Paraffin from a stream of Normal and Non-normal by means of physical selective Adsorption. The feedstock, essentially having same properties of kerosene is separated into high purity Normal Paraffin section at high recoveries and a Non-normal fraction. The Process includes Counter-Current contact between a fixed bed Adsorbent and the feed stream. It uses a solid adsorbent, liquid desorbent and a flow directing device called a Rotary Valve. The Molex Process does the separation by adsorption Process. Adsorption can be defined as the adheration of liquid or gas on solid surface. The solid surface is called the Adsorbent. It is convenient to visualize the Adsorbent as a porous solid having certain characteristics. When the solids are immersed in a liquid mixture, the pores become filled with liquid. The Adsorbent employed in the Molex Process is a specially designed Molecular Sieve which is made of Zeolite Crystals. The pore diameter of the Sieve is selected so that Normal Paraffin can pass through the pores and other species are retained or excluded because of their sizes. The non adsorbed 21

Branched and Cyclic Paraffin referred to as Non-normal may become entrained in the large sieve voids but easily removed by washing Adsorbent with a Non-desorptive Hydro-carbon, such as iso-Octane (iC8). This effectively flushes the Non-normal, while easily leaving the Adsorbed Paraffin intact. To displace Normal Paraffin from the selective pore, short linear chained Paraffin such as Normal Pentane (nC5) must be used. By virtue of its short length and small diameter the nC5 is extremely mobile and can pass into selective pores of the Sieve and displace the larger C10-C13 Normal Paraffin. Table 2.4.3 Contents of Molex Adsorbent Content

Weight %

Silicon Oxide

< 50

Aluminum Oxide

< 40

Calcium Oxide

< 20

Sodium Oxide

< 15

Adsorbent theory: The adsorbent is a porous solid having certain characteristics. Each adsorbent piece is composed of crystals of Zeolite. When the solid is immersed in a liquid mixture, the pores become filled with liquid. At equilibrium (Equilibrium is the term used to describe a situation where no net change is occurring.), the composition of the liquid in the pores will be different from that of the liquid surrounding the particles. The adsorbent is said to be physically selective for the component that is more concentrated in the pores than in the surrounding liquid. The structures of the Molex Feed constituents are shown in the figures below.

N-Paraffin

Iso-Paraffin

22

Alkyl Naphthene

Alkyl Aromatic Fig 2.4.9 Molex feed From the structures, it may be seen that the n-paraffin has a much smaller maximum diameter (in plane normal to the carbon – carbon bonds) than the other species present. The pore diameter of the sieve is selected so that the n – paraffin can pass through the pores and into the cavities within the crystal structure, while the other species are excluded because of their size. It is shown in Figure 4.6 below. The non – adsorbed branched and cyclic paraffins referred to as non – normals, may become entrained in the large sieve voids but are easily removed by washing the adsorbent with a non – desorptive hydrocarbon such as iso-octane (iC8). The iC8 effectively flushes away the non – normals while leaving the adsorbed n-paraffins intact. To displace the n-paraffins from the selective pores, a short linear chained paraffins such as n-pentane (nC5) must be used. By virtue of its short length and small diameter, the nC5 is extremely mobile and can easily pass into the selective pores of the sieve and displace the larger C10 – C13 n-paraffins.

Adsorptive separation with moving bed

Figure 2.4.10 Moving bed system 23

The adsorbent circulates continuously as a dense bed, in a closed cycle, and moves up the adsorbent chamber from bottom to top. Liquid streams flow down through the bed, countercurrent to the solid. For simplicity, the feed is assumed to be a binary mixture A and B, with component a being more selectively adsorbed relative to B. Feed is introduced to the bed as shown. Desorbent, D is introduced to the moving bed model at a point above the extract location. The desorbent is a liquid of a higher boiling point than the feed components and having a high adsorbent selectively. This means that the desorbent can desorbs the feed components from the adsorbent and in downstream fractionation can be separated from the feed components. Raffinate product, consisting of the less strongly adsorbed component B mixed with desorbent is withdrawn as shown from a position below the feed entry. Extract product, consisting of the more strongly adsorbed component A mixed with desorbent is withdrawn from the chamber above the feed point. Only a portion of the flowing liquid in the bed is withdrawn, and the remainder continues to flow in a closed loop. The positions of introduction and withdrawal of net streams divide the bed into four main zones, each of which performs a different function. The zones are described below:

Zone I Adsorption Zone: Zone I is defined as the section between the Feed and Raffinate points. The primary function of Zone I is to adsorb A from the liquid. The solid entering the bottom of this zone carries only B and D in its pores. As the liquid stream flows downward, countercurrent to this solid, component A is transferred from the liquid stream into the pores of the solid. At the same time, some of the components B and D are desorbed from the pores due to concentration driving forces and selectivity differences. This means it is transferred from the pores to the liquid stream making room for A in the pores. Zone 1 is the zone in which normal paraffin is adsorbed from the liquid phase. Thus, it is referred to as the adsorption zone. Zone II Purification Zone: Zone II is defined as the section between the extract and feed points. The primary function of Zone 2 is to remove B from the pores of the solid. When the solid arrives at the feed point, the pores will contain the quantity of A that was adsorbed in Zone I. However, the pores will also contain a large quantity of B, because the solid does not make a perfect separation. The liquid entering the top of Zone 2 contains no B – only A and D. As the solid moves upward, B is gradually displaced from the pores and is replaced by A and D. Thus, when 24

the solid arrives at the top of Zone 2, the pores will contain only A and D. By proper regulation of the liquid rate in Zone 2, B can be desorbed almost completely from the pores. This can be done without simultaneously desorbing all of A, because A is more strongly adsorbed than B. Zone 2 is the zone in which normal paraffin is purified. Thus, is referred to as the purification zone. Zone III

Desorption Zone Zone III is defined as the section between the desorbent and extract points. The

function of this zone is to desorb A from the pores. The solid entering the bottom of the zone carries A and D in the pores; the liquid entering the top of the zone consists of pure D. As the solid rises, A in the pores is displaced by D. Zone 3 is the zone in which normal paraffin is desorbed from the solid. Thus, it is referred to as the desorption zone. Zone IV Buffer Zone: Zone IV is defined as the section between the Raffinate and desorbent points. The purpose of Zone 4 is to keep components B, which is at the bottom of Zone 1, from entering Zone 4 and flowing through Zone 4 to Zone 3 where it can contaminate the extract material. If the flow rate is set such that desorbent flows up in Zone 4, raffinate material would be prevented from gaining access to Zone 3 where it would contaminate the purified extract stream. This means that the main function of Zone 4 is to separate Zone 3 from Zone 1 and as a result it is referred to as the buffer zone. For the liquid-solid system each stage has to mix the solid with the liquid and subsequently separate the two phases after equilibrium is reached. The liquid and solid can then be passed on to the next stages. To make another comparison with distillation, the liquid could be seen as passing up through a column with trays that the solid is passing down through. At each tray the solid would be pushed across. The solid would fall to the tray below and the liquid would pass to the tray above.

25

2.4.3.3.2 Process flow diagram

Figure 2.4.11: Adsorption Chamber

Figure 2.4.12: Extract column

26

Figure 2.4.13: Desorbent stripper column

Figure 2.4.14: Raffinate column

27

2.4.3.3.3 Process flow description Feed is pumped from the union fining process unit & is charged in to feed surge drum of Molex unit. In this tank the level is maintained for continuous supply of feed & nitrogen blanketing is provided for preventing of vapor loss & fire formation. From feed surge drum the feed is transferred to screen feed filters for removal of suspended impurities in the size range of 10 microns & greater so as to prevent clogging in further treatment & poisoning of beds. As the feed filters, flush filters & desorbent filters provide zone flush, feed, and line flush and desorbent. All these materials are inlet of rotary valve which does the function of sending proper material to the proper bed in the chamber at proper time. It is the heart of the Molex unit. The feed enters the adsorbent chambers where adsorption of n-paraffin from its mixture of non-normal paraffin for this adsorption the molecular sieve beds are provided in which selective & non selective pores are provided. There are two chambers in which 12 molecular sieve beds are provided in each adsorption tower. The pump around system is provided to circulate material from 12th bed to 13th bed & from 24th bed to 1st bed. In the selective pores the n-paraffin are adsorbed while the non-normal paraffin are adsorbed in the non-selective pores. The n-paraffin are displaced by n-C5 & non normal paraffin are displaced by i-C8. The n-paraffin with i-C8 & n-C5 are obtained as extract while non normal paraffin nC5 & iC8 are obtained raffinate. The raffinate, extract & line flush out are obtained as product from the chambers which goes to the rotary valve the line flush does the work of flushing the bed before entry of feed while zone flush does the flushing of the proper zone. The rotary valve again sends the extract; raffinate & line flush out lines to the proper destination. The extract goes to extract mixing drum which is provided for continuous flow to the extract column & for mixing of the extract effectively as extract comes in short intervals. In the extract column feed enters at the 26th tray. In here simple distillation occurs on temp. difference where the n-C5 is removed as the top product, i-C8 gets removed as side cut & the n-paraffin are removed as the bottom product & sent for further processing. The n-C5 obtained as top product is recycled as some part while other part gets divided in to two parts one of each goes to desorbent surge drum & other goes to desorbent stripper column. The i-C8 is obtained as side cut which is sent to desorbent stripper column for obtaining it in pure form. The raffinate goes to the raffinate mixing drum which has the same function as that of 11extract mixing drum. The raffinate from there goes to raffinate column where top and side products are same as that of the extract column while the bottom product is non normal paraffin 28

which is sent to the return kerosene. In the desorbent surge drum 60:40 ratio by volume of nC5 & i-C8 is maintained. In desorbent stripper column the separation of n-C5 & i-C8 is done where i-C8 is obtained as 99% pure & sent to desorbent surge drum, filters, zone & line flush for the same process while the n- C5 is sent to surge drum. Some portion of n-C5 & i-C8 is also sent to storage tank.

2.4.3.3.4 Process equipment [1] Rotary valve: It is a device through which the bed mechanism is controlled in the adsorption chamber. In rotary valve there is a rotor and a stator plate. Each plate containing 24 holes in its periphery. Bottom plate which is static in nature is having all holes in open condition and the top plate which is rotary has 7 open holes. These whole openings is followed by the mechanism of 6-15-1-7-1-3. After a fix time, a stroke is applied on the system so that the feed position is changes from one bed to second one. This means that each stream goes to one number higher position than the previous one. This is done by hydraulic system in which the oil is used at a pressure of 80 Kg/cm2.

[2] Adsorption chamber: The vessels that contain the Molecular Adsorbent and the Distributor Grids are called Chambers. Between two adjacent beds of adsorbent is a special distributor grid which also acts as a support plate for the bed above it. Distributors between each bed are connected to peripheral parts of the Rotary Valve. In addition to these, grids are provided at top and bottom of each chamber. Liquid is pumped to and from the chambers. The two process variables for the chambers that need to be controlled are Temperature and Pressure.

The chamber

Temperature is controlled by incoming feed and desorbent system at approximately 177 0C. The Pressure is set at 24.6 kg/cm2 which are high enough to prevent Hydro-carbon from vaporizing. If pressure falls below the bubble point, liquid will boil and vaporize and this is to be prevented as vaporization may damage adsorbent structure. Pressure also is an important factor. There is an emergency system for preventing loss in pressure. The switch on chamber to control the pressure closes the Extract valve if pressure falls below the determined point.

29

[3] Extract and raffinate column: The primary purposes of both columns are to separate the recyclable desorbent and yield a purified bottom product, Normal paraffin from the extract and Non-normal paraffin from raffinate, as well as to provide feed source to desorbent stripper column. Bottom product level controller and pure products are sent to storage after cooling. Bottom product is recycled for high recovery. The overhead vapor is condensed and dropped to receiver. Bypass line connects the receiver with vapor line to control pressure by Butterfly valve. It is desirable to run outlet condenser at temperature slightly less than condensing temperature because if the temperature is high all vapors will condense and if it is too low heat will be wasted. The side cut product from raffinate column is pumped to desorbent stripper on flow control. Suction for this is provided. The side cut’s major portion is given back to column tray below weir. This rate is controlled by TRC located few trays below weir. The net overhead from the raffinate column is pumped out on flow control by level in receiver to desorbent surge drum. The reflux to extract column is pumped by reflux pump. The amount is reset by overhead receiver level controller. The other net draw is sent to desorbent surge drum. The iC8 rich side cut is sent to the stripper desorbent. It is important to maintain tight and accurate control as loss of normal Paraffin decreases purity and recovery causing the loss of desorbent.

[5] Desorbent stripper column: This is typically a 20-30 tray vessel. The objective is to produce high purity of iC 8 as nC5 contamination will reduce purity. The Extract and Raffinate Column side cut streams merge and enter the Stripper Column. Purified iC8 exists at bottom and is pumped through Desorbent Stripper Column bottom heater to filter and the same process repeats again. Temperature of Zone Flush leaving Exchanger is regulated by flow control of Hot Oil. Desorbent Stripper overhead is nC5 and is returned to the Raffinate Column to a point just above the side cut tray.

[6] Filters: Filters are located in three streams leading to Adsorbent Chambers feed, Desorbent and Flush. Filters remove particles that could damage Turbine Meters, Vortex Meter or the Rotary Valve Teflon Sheet. The Filters have replaceable Cartridges. These should be initially placed to remove particles from the system. It can remove particles of diameter 10 microns and larger. Strainers are provided to protect the turbine meters if Filters are out of Streams.

30

B. Back end 2.4.3.4 Paraffin converted to olefin (Pacol) 2.4.3.4.1 Introduction The process is a fixed bed catalytic process designed to selectively dehydrogenate a high purity, normal paraffin feed to the corresponding mono olefins. The feed to the Pacol unit must be free from impurities which could harm the catalyst and contains maximum of four carbon range of normal paraffin [C10 – C13].The catalyst is a 1/16” spherical dehydrogenation catalyst of stabilized platinum on alumina base. It is non- regenerable and pre-reduced as received by the refinery. The catalyst used in the Pacol section is of high selectivity for the desired reaction and thereby minimizing the side reactions. If selectivity of normal monoolefin is maintained reasonably high, the conversion of paraffin to olefin is limited at low levels. Thus recycling of untreated normal paraffin is moderately high. PACOL reactor reaction is carried out in a low pressure hydrogen environment at moderately high temperature (low hydrogen partial pressure) in presence of Nickel catalyst (DEH-7). The life of this catalyst is around 30-45 days depending upon operating conditions. The product also produces small amount of Di-olefins which forms undesirable byproduct thereby decreasing the yield of LAB and degrading LAB quality. These Di-olefins are converted into mono-olefins in DEFINE section. Reaction [Dehydrogenation Reaction] [1] Olefin formation R-C-C-R’ N-paraffin

R-C=C-R’ + H2 mono-olefin

[2] Diolefin formation R-C-C=C-R’ Mono-olefin

R=C-C=C-R’ + H2 Di-olefin

[3] Aromatics Formation

R” R=C-C=C-R’ R”’

The primary reaction of Pacol unit is dehydrogenation of normal paraffin into monoolefins, the desired product [Saturated to unsaturated].

31

In this dehydrogenation reaction of normal paraffin because of high temperature [450-500 °C] and low pressure [1.4 Kg/cm2] subsequently Di-olefins and aromatics are also formed by the side reactions to minor extent. The dehydrogenation reaction of n-paraffin is an endothermic reaction. The percentage conversion of n-paraffin is 10-13% into mono-olefins, Di-olefins, light ends, aromatics & hydrogen. Pacol catalyst: The catalyst is a 1/16” spherical dehydrogenation catalyst of stabilized platinum on alumina base & it is non- regenerable. It is dark gray in color and is odorless. It is in the form of spheres.

Table 2.4.4 Contents of Pacol catalyst Content

Weight%

Platinum

Mono-olefins + H2 B) Paraffin-----> Di-olefins + 2H2 Conversion (Wt basis)

13.00%

Selectivity towards mono-olefins

80.00%

So to give full conversion to 12307.4754 Kg/hr of material total amount of feed required to be equals…

KG/HR Feed Required

94672.89

Mono-olefins + H2

9845.98

Di-olefins + 2H2

2461.50

Unconverted amount(PARAFFINS)

82365.41

In this section hydrogen is removed from the feed and Mono-olefins and Di-olefins are generated by the reaction shown above. Conversion of paraffin to the mono-olefins is too low (around 11-13%).

63

Feed to PACOL from FRONTEND

MOLE COMPONENT

KGMOL/HR

MOL. WT

FRACTION

KG/HR

H2O

0

18.00

0

0

NC7

0

100.00

0

0

NC8

0

114.00

0

0

NC9

0

128.00

0

0

NC10

133.581223

142.00

0.228476202

18968.53363

NC11

178.314502

156.00

0.304987626

27817.0623

NC12

159.544554

170.00

0.272883666

27122.57424

NC13

106.794012

184.00

0.182659582

19650.09828

NC14

2.09621749

198.00

0.003585353

415.0510628

NC15

0

212.00

0

0

NC16

0

226.00

0

0

NC17

0

240.00

0

0

NNC7

0

100.00

0

0

NNC8

0

114.00

0

0

NNC9

0.00971663

128.00

1.66192E-05

1.243728195

NNC10

1.02855634

142.00

0.001759234

146.0550001

NNC11

1.32599808

156.00

0.002267976

206.8557005

NNC12

1.18587707

170.00

0.002028314

201.599102

NNC13

0.76990203

184.00

0.001316834

141.6619733

NNC14

0.0108712

198.00

1.8594E-05

2.152496796

NNC15

0

212.00

0

0

NNC16

0

226.00

0

0

NNC17

0

240.00

0

0

Total

584.66143

1

94672.88752

64

Reaction Products

MONO-OLEFINS + H2

MOLE COMPONENT

KGMOL/HR

MOL. WT

FRACTION

KG/HR

H2O

0

18.00

0

0

NC7

0

100.00

0

0

NC8

0

114.00

0

0

NC9

0

128.00

0

0

NC10

13.89244717

142.00

0.228476202

1972.727498

NC11

18.5447082

156.00

0.304987626

2892.974479

NC12

16.59263365

170.00

0.272883666

2820.747721

NC13

11.10657729

184.00

0.182659582

2043.610222

NC14

0.218006619

198.00

0.003585353

43.16531053

NC15

0

212.00

0

0

NC16

0

226.00

0

0

NC17

0

240.00

0

0

NNC7

0

100.00

0

0

NNC8

0

114.00

0

0

NNC9

0.001010529

128.00

1.66192E-05

0.129347732

NNC10

0.106969859

142.00

0.001759234

15.18972001

NNC11

0.1379038

156.00

0.002267976

21.51299285

NNC12

0.123331215

170.00

0.002028314

20.96630661

NNC13

0.080069811

184.00

0.001316834

14.73284522

NNC14

0.001130604

198.00

1.8594E-05

0.223859667

NNC15

0

212.00

0

0

NNC16

0

226.00

0

0

NNC17

0

240.00

0

0

Total

60.80478875

1

9845.980302

65

DI-OLEFINS + H2

MOLE COMPONENT

KGMOL/HR

MOL. WT

FRACTION

KG/HR

H2O

0

18.00

0

0

NC7

0

100.00

0

0

NC8

0

114.00

0

0

NC9

0

128.00

0

0

NC10

3.473111792

142.00

0.228476202

493.1818745

NC11

4.63617705

156.00

0.304987626

723.2436197

NC12

4.148158413

170.00

0.272883666

705.1869302

NC13

2.776644323

184.00

0.182659582

510.9025554

NC14

0.054501655

198.00

0.003585353

10.79132763

NC15

0

212.00

0

0

NC16

0

226.00

0

0

NC17

0

240.00

0

0

NNC7

0

100.00

0

0

NNC8

0

114.00

0

0

NNC9

0.000252632

128.00

1.66192E-05

0.032336933

NNC10

0.026742465

142.00

0.001759234

3.797430002

NNC11

0.03447595

156.00

0.002267976

5.378248212

NNC12

0.030832804

170.00

0.002028314

5.241576653

NNC13

0.020017453

184.00

0.001316834

3.683211305

NNC14

0.000282651

198.00

1.8594E-05

0.055964917

NNC15

0

212.00

0

0

NNC16

0

226.00

0

0

NNC17

0

240.00

0

0

Total

15.20119719

1

2461.495075

66

Unconverted Paraffins

MOLE COMPONENT

KGMOL/HR

MOL. WT

FRACTION

KG/HR

H2O

0

18.00

0

0

NC7

0

100.00

0

0

NC8

0

114.00

0

0

NC9

0

128.00

0

0

NC10

116.2156638

142.00

0.228476202

16502.6

NC11

155.1336167

156.00

0.304987626

24200.8

NC12

138.8037623

170.00

0.272883666

23596.6

NC13

92.9107908

184.00

0.182659582

17095.6

NC14

1.823709215

198.00

0.003585353

361.094

NC15

0

212.00

0

0

NC16

0

226.00

0

0

NC17

0

240.00

0

0

NNC7

0

100.00

0

0

NNC8

0

114.00

0

0

NNC9

0.008453465

128.00

1.66192E-05

1.08204

NNC10

0.894844015

142.00

0.001759234

127.068

NNC11

1.15361833

156.00

0.002267976

179.964

NNC12

1.031713052

170.00

0.002028314

175.391

NNC13

0.669814765

184.00

0.001316834

123.246

NNC14

0.00945794

198.00

1.8594E-05

1.87267

NNC15

0

212.00

0

0

NNC16

0

226.00

0

0

NNC17

0

240.00

0

0

Total

508.6554443

1

82365.4

67

Final Product without consideration of H2

MONO-OLEFINS (-H2) MOLE COMPONEN

FRACTIO

T

KGMOL/HR

KG/HR

MOL WT

N

H2O

0.00

0.00

18.00

0

NC7

0.00

0.00

98.00

0

NC8

0.00

0.00

112.00

0

NC9

0.00

0.00

126.00

0

NC10

13.89

1944.94

140.00 0.228476202

NC11

18.54

2855.89

154.00 0.304987626

NC12

16.59

2787.56

168.00 0.272883666

NC13

11.11

2021.40

182.00 0.182659582

NC14

0.22

42.73

196.00 0.003585353

NC15

0.00

0.00

210.00

0

NC16

0.00

0.00

224.00

0

NC17

0.00

0.00

238.00

0

NNC7

0.00

0.00

98.00

0

NNC8

0.00

0.00

112.00

0

NNC9

0.00

0.13

126.00 1.66192E-05

NNC10

0.11

14.98

140.00 0.001759234

NNC11

0.14

21.24

154.00 0.002267976

NNC12

0.12

20.72

168.00 0.002028314

NNC13

0.08

14.57

182.00 0.001316834

NNC14

0.00

0.22

196.00

1.8594E-05

NNC15

0.00

0.00

210.00

0

NNC16

0.00

0.00

224.00

0

NNC17

0.00

0.00

238.00

0

TOTAL

60.80

9724.37

1

68

DI-OLEFINS (-2 H2)

MOLE COMPONENT

KGMOL/HR

KG/HR

MOL WT

FRACTION

H2O

0.00

0.00

18.00

0

NC7

0.00

0.00

96.00

0

NC8

0.00

0.00

110.00

0

NC9

0.00

0.00

124.00

0

NC10

3.47

479.29

138.00

0.228476202

NC11

4.64

704.70

152.00

0.304987626

NC12

4.15

688.59

166.00

0.272883666

NC13

2.78

499.80

180.00

0.182659582

NC14

0.05

10.57

194.00

0.003585353

NC15

0.00

0.00

208.00

0

NC16

0.00

0.00

222.00

0

NC17

0.00

0.00

236.00

0

NNC7

0.00

0.00

96.00

0

NNC8

0.00

0.00

110.00

0

NNC9

0.00

0.03

124.00

1.66192E-05

NNC10

0.03

3.69

138.00

0.001759234

NNC11

0.03

5.24

152.00

0.002267976

NNC12

0.03

5.12

166.00

0.002028314

NNC13

0.02

3.60

180.00

0.001316834

NNC14

0.00

0.05

194.00

1.8594E-05

NNC15

0.00

0.00

208.00

0

NNC16

0.00

0.00

222.00

0

NNC17

0.00

0.00

236.00

0

TOTAL

15.20

2400.69

1

69

UNCONVERTED MATERIAL

MOLE KGMOLE/HR

KG/HR

MOL WT

FRACTION

0.00

0.00

18.00

0

0.00

0.00

100.00

0

0.00

0.00

114.00

0

0.00

0.00

128.00

0

116.22

16502.62

142.00

0.228476202

155.13

24200.84

156.00

0.304987626

138.80

23596.64

170.00

0.272883666

92.91

17095.59

184.00

0.182659582

1.82

361.09

198.00

0.003585353

0.00

0.00

212.00

0

0.00

0.00

226.00

0

0.00

0.00

240.00

0

0.00

0.00

100.00

0

0.00

0.00

114.00

0

0.01

1.08

128.00

1.66192E-05

0.89

127.07

142.00

0.001759234

1.15

179.96

156.00

0.002267976

1.03

175.39

170.00

0.002028314

0.67

123.25

184.00

0.001316834

0.01

1.87

198.00

1.8594E-05

0.00

0.00

212.00

0

0.00

0.00

226.00

0

0.00

0.00

240.00

0

508.66

82365.41

1

70

In Kmole/hr Total product to define in Kg/hr

94490.47

584.66

Hydrogen produced in this reaction in Kg/hr

182.41 in Mol/hr

91.20718312

9724.37 Kg/hr (Mono-olefins)

94672.89 Kg/Hr (Feed)

PACOL Unit

82365.81 Kg/hr (Paraffins)

2400.69 Kg/hr (Di-olefins)

C. DEFINE UNIT A) Di-olefins + H2------> Mono-olefins B) Di-olefins + 2H2-----> Paraffin

Feed from PACOL reactor

KGMOL/HR

AVG MOL WT

584.66

212.00

Conversion (Wt%)

90.00%

Selectivity

50.00%

In this section, di-olefins gets convert into the mono olefins. In this process for the conversion of di-olefins into the mono olefins or paraffin hydrogen is added to the di-olefins. After the conversion total feed is fed to the detergent alkylation section for the production of the LAB.

71

DI-OLEFINS CONVERSION TO MONO-OLEFINS

MOLE COMPONENT

KGMOL/HR

KG/HR

MOL WT

FRACTION

H2O

0.00

0.00

18.00

0

NC7

0.00

0.00

96.00

0

NC8

0.00

0.00

110.00

0

NC9

0.00

0.00

124.00

0

NC10

1.56

215.68

138.00

0.228476202

NC11

2.09

317.11

152.00

0.304987626

NC12

1.87

309.87

166.00

0.272883666

NC13

1.25

224.91

180.00

0.182659582

NC14

0.02

4.76

194.00

0.003585353

NC15

0.00

0.00

208.00

0

NC16

0.00

0.00

222.00

0

NC17

0.00

0.00

236.00

0

NNC7

0.00

0.00

96.00

0

NNC8

0.00

0.00

110.00

0

NNC9

0.00

0.01

124.00

1.66192E-05

NNC10

0.01

1.66

138.00

0.001759234

NNC11

0.02

2.36

152.00

0.002267976

NNC12

0.01

2.30

166.00

0.002028314

NNC13

0.01

1.62

180.00

0.001316834

NNC14

0.00

0.02

194.00

1.8594E-05

NNC15

0.00

0.00

208.00

0

NNC16

0.00

0.00

222.00

0

NNC17

0.00

0.00

236.00

0

TOTAL

6.84

1080.31

1

72

PARAFFIN

COMPONENT

KGMOL/HR

KG/HR

MOL WT

H2O

0

0

18.00

NC7

0

0

96.00

NC8

0

0

110.00

NC9

0

0

124.00

NC10

1.56290031

215.6802423

138.00

NC11

2.08627967

317.1145102

152.00

NC12

1.86667129

309.8674334

166.00

NC13

1.24948995

224.9081901

180.00

NC14

0.02452574

4.757994456

194.00

NC15

0

0

208.00

NC16

0

0

222.00

NC17

0

0

236.00

NNC7

0

0

96.00

NNC8

0

0

110.00

NNC9

0.00011368

0.014096882

124.00

NNC10

0.01203411

1.660707064

138.00

NNC11

0.01551418

2.358154985

152.00

NNC12

0.01387476

2.303210447

166.00

NNC13

0.00900785

1.621413672

180.00

NNC14

0.00012719

0.024675441

194.00

NNC15

0

0

208.00

NNC16

0

0

222.00

NNC17

0

0

236.00

TOTAL

6.84053873

1080.310629

73

UNCONVERTED DI-OLEFINS

COMPONENT

KGMOL/HR

KG/HR

MOL WT

H2O

0

0

18.00

NC7

0

0

96.00

NC8

0

0

110.00

NC9

0

0

124.00

NC10

0.347311179

47.9289427

138.00

NC11

0.463617705

70.4698912

152.00

NC12

0.414815841

68.8594297

166.00

NC13

0.277664432

49.9795978

180.00

NC14

0.005450165

1.0573321

194.00

NC15

0

0

208.00

NC16

0

0

222.00

NC17

0

0

236.00

NNC7

0

0

96.00

NNC8

0

0

110.00

NNC9

2.52632E-05

0.00313264

124.00

NNC10

0.002674246

0.36904601

138.00

NNC11

0.003447595

0.52403444

152.00

NNC12

0.00308328

0.51182454

166.00

NNC13

0.002001745

0.36031415

180.00

NNC14

2.82651E-05

0.00548343

194.00

NNC15

0

0

208.00

NNC16

0

0

222.00

NNC17

0

0

236.00

TOTAL

1.520119719

240.069029

74

FINAL PRODUCT FROM DEFINE REACTOR

MONO-OLEFINS COMPONENT

KGMOL/HR

KG/HR

MOL WT

H2O

0

0

18

NC7

0

0

98

NC8

0

0

112

NC9

0

0

126

NC10

15.45534747

2163.75

140

NC11

20.63098787

3177.17

154

NC12

18.45930494

3101.16

168

NC13

12.35606724

2248.8

182

NC14

0.242532363

47.5363

196

NC15

0

0

210

NC16

0

0

224

NC17

0

0

238

NNC7

0

0

98

NNC8

0

0

112

NNC9

0.001124214

0.14165

126

NNC10

0.119003968

16.6606

140

NNC11

0.153417978

23.6264

154

NNC12

0.137205977

23.0506

168

NNC13

0.089077665

16.2121

182

NNC14

0.001257797

0.24653

196

NNC15

0

0

210

NNC16

0

0

224

NNC17

0

0

238

TOTAL

67.64532748

10818.4

75

DI-OLEFINS

COMPONENT

KGMOL/HR

KG/HR

MOL WT

H2O

0

0

18.00

NC7

0

0

98.00

NC8

0

0

112.00

NC9

0

0

126.00

NC10

0.347311179

47.9289

140.00

NC11

0.463617705

70.4699

154.00

NC12

0.414815841

68.8594

168.00

NC13

0.277664432

49.9796

182.00

NC14

0.005450165

1.05733

196.00

NC15

0

0

210.00

NC16

0

0

224.00

NC17

0

0

238.00

NNC7

0

0

98.00

NNC8

0

0

112.00

NNC9

2.52632E-05

0.00313

126.00

NNC10

0.002674246

0.36905

140.00

NNC11

0.003447595

0.52403

154.00

NNC12

0.00308328

0.51182

168.00

NNC13

0.002001745

0.36031

182.00

NNC14

2.82651E-05

0.00548

196.00

NNC15

0

0

210.00

NNC16

0

0

224.00

NNC17

0

0

238.00

TOTAL

1.520119719

240.069

76

PARAFFINS

COMPONENT

KGMOL/HR

KG/HR

MOL WT

H2O

0

0

18

NC7

0

0

100

NC8

0

0

114

NC9

0

0

128

NC10

117.77856

16725

142

NC11

157.2199

24526

156

NC12

140.67043

23914

170

NC13

94.160281

17325

184

NC14

1.848235

366

198

NC15

0

0

212

NC16

0

0

226

NC17

0

0

240

NNC7

0

0

100

NNC8

0

0

114

NNC9

0.0085671

1.097

128

NNC10

0.9068781

128.8

142

NNC11

1.1691325

182.4

156

NNC12

1.0455878

177.7

170

NNC13

0.6788226

124.9

184

NNC14

0.0095851

1.898

198

NNC15

0

0

212

NNC16

0

0

226

NNC17

0

0

240

TOTAL

515.49598

83473

77

Amount of Paraffins recycled to the PACOL unit

82365.41

Amount of Paraffins to Hot oil heater

1107.67

Mol/hr

Kg/hr

Amount of H2 used in DEFINE

20.5216162

41.0432324

D. DETAL UNIT 1)DETAL REACTOR Reaction: n-Olefins+Benzene------>LAB nn-olefins+diolefins+Benzene----->HAB Conversion (wt %)

99.95%

Moles/hr

M.W.

Kg/hr

Feed from DEFINE

584.66143

161.6859117 94531.51638

Benzene required

71.0346221

78 5540.700526

Moles of Normal olefins

66.9017075

M.W. of LAB

LAB

237.78

MOLE/HR

KG/HR

66.8682567

15900.00

78

Moles of Non-normal olefins+Moles of diolefins

M.W. of HAB

2.018825307

343.742608

MOLE/HR HAB

2.01781589

Unconverted olefins in Kg/hr

5.52921573

KG/HR 693.6092983

Overall material balance for back end unit Inputs

Kg/hr Outputs

Kg/hr

From Molex

12307.4754 LAB

15900.00

Hydrogen to DEFINE

41.0432324 HAB

693.6092983

Benzene to DETAL

5540.70053 Unconverted Olefins Excess paraffins to HOH H2 from PACOL

TOTAL

17889.2191

5.52921573 1107.67 182.41 17889.22586

79

3.3 BLOCK DIAGRAM OF OVERALL M.B. Figure 3.1: Block Dia. Of overall M.B. C7-C9

TNN

12709.31 KG/HR

45358.71 KG/HR

C10-C13 KEROSENE PRE FRACTIONAPTION 92865.96 KG/HR

TNP

(TNP+TNN)

MOLEX 12307.48 KG/HR

50746.01 KG/HR 29410.65 KG/HR C14-C17

RECYCLE TNP

5540.78 KG/HR

82365 KG/HR

BENZENE H2 MONO + DI 0LEFINS + TNP PACOL

41.03 KG/HR MONO + TNP

DEFINE

TNP

94490.47 KG/HR

DETAL 94531 KG/HR

H2 182.41 KG/HR

15900 KG/HR

LAB C10-C13

HAB 693.60 KG/HR

80

CHAPTER 4: ENERGY BALANCE

81

4.1 INTRODUCTION All chemical processes involve certain chemical reactions at particular conditions of temperature and pressure to produce a desired product. To achieve these conditions of heating or cooling a stream and for proper functioning of equipment, various entities such as demineralized water, cooling water, chilling water , high pressure, medium pressure, low pressure steam , electricity etc. are used. These entities are called UTILITIES. Utilities do not take part in the process but they only make the conditions favorable for any process. Energy balance is a calculation done to calculate the load on utilities. It is used to calculate the amount of utilities required by the system to reach optimum conditions. Thus, the load calculation for cooling water is used to determine the total cooling water requirements and thus used to find the capacity of cooling tower, size of fans steam etc. Similarly, the load calculation for steam is used to determine the capacity of boiler Energy balance requires knowledge of thermodynamics. The heat duty on process side and utility side is matched in order to calculate the load on the utilities. Proper values of heat capacities, latent heat of vaporization, latent heat of condensations etc at their respective temperatures are needed to be incorporated in the calculation.

Utilities used:1) THERMINOL Cp=

1.496005+0.003313*T+0.0000008970785*T2

KJ/KGC

2) MP STEAM LATENT HEAT, λ

512.89 KCAL/KG 2147.35 KJ/KG

3) AIR Cp=

(3.355+0.000575*T)*(8.314/29) KJ/KGK

82

HORSE POWER

DENSITY OF AIR AT STD

REQUIRED

CONDITION

0.0756 lb/ft3

NOTE: 1 KG/HR

=

0.486 SCFM IN OF

Pt

=

0.3 H20

ef

=

0.65

ed

=

0.95

=

6356

CONVERSION FACOTR ASSUME: ACFM

= SCFM

ef= FAN SYSTEM EFFICIENCY ed= SPEED REDUCER EFFICIENCY

4) FUEL OIL CALORIFIC VALUE

9520 KCAL/KG 39848.816 KJ/KG

5) COOLING WATER Cp=

(3.470+0.001450*T)*(8.314/18) KJ/KGK

83

1) HEAT LOAD AROUND STRIPPER COLUMN REBOILER 1 KCAL=

4184.1004

SHELL SIDE : HC

IN

MASS FLOW (KG/HR)

294976.509

TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

236 Cp=

0.520225

36215.1804 42091.0976 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR)

294976.509

TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

1248.4648

243 Cp=

0.52433

37289.3595 43339.5624

TUBESIDE : OIL

IN

TEMPERATURE

300

INT(Cp*Dt)

58.109751

MASS FLOW (KG/HR) OUT

TEMPERATURE

77344.56

277

2) HEAT LOAD AROUND FIN FAN COOLER

HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR)

330317.26 158 Cp=

0.91883

47953.8545 84

( KILOWATT)

55734.3729 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

AIR

IN

TEMPERATURE (DEG C)

44518.481

330317.262 77 Cp=

0.379413

9650.15307 11215.8915

35 Q=INT(M*Cp*DT) INT(Cp*dT)

25.366928

MASS FLOW

OUT

TEMPERATURE (DEG C)

(KG/HR)

6317932.3

HP REQUIRED

234.69922

60

3) HEAT LOAD AROUND RERUN COLUMN REBOILER

SHELL SIDE: HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

326929.065 249 Cp=

0.524601

42705.3213 49634.2647 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

5104.6748

326929.065 249 Cp=

0.578554

47097.3835 54738.9395 85

TUDE SIDE: OIL

IN

TEMPERATURE(DEG C)

300 Q=INT(M*Cp*DT) INT(Cp*dT)

92.492724

MASS FLOW (KG/HR) OUT

TEMPERATURE(DEG C)

198684.05

263

4) HEAT LOAD AROUND RERUN COLUMN PUMP AROUND COOLER

HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

150463.01 140 Cp=

0.328111

6911.59961 8033.00746 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

AIR

IN

TEMPERATURE (DEG C)

5813.1167

150463.01 55 Cp=

230.802

1909.994 2219.89075

35 Q=INT(M*Cp*DT) INT(Cp*dT)

25.366928

MASS FLOW

OUT

TEMPERATURE (DEG C)

(KG/HR)

824980.47

HP REQUIRED

30.646462

60

86

5) HEAT LOAD AROUND RAFFINATE COLUMN REBOILER

SHELL SIDE: HC

IN

MASS FLOW (KG/HR)

280101.824

TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

243 Cp=

0.50846

34608.1994 40223.3838 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR)

280101.824

TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

6222.1749

246 Cp=

0.579954

39961.7587 46445.5587

TUBE SIDE: OIL

IN

TEMPERATURE (DEG C)

300 Q=INT(M*Cp*DT) INT(Cp*dT)

137.96971

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

162353.24

244

6) HEAT LOAD AROUND RAFFINATE COLUMN CONDENSER

HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

67558.62 94 Cp=

1.2398

7873.36265 9150.81665 CHANGE IN ENTHALPY (KW)

7451.3456 87

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

AIR

IN

TEMPERATURE (DEG C)

67558.62 54 Cp=

0.400811

1462.22485 1699.47101

35 Q=INT(M*Cp*DT) INT(Cp*dT)

25.366928

MASS FLOW

OUT

TEMPERATURE (DEG C)

(KG/HR)

1057473.1

HP REQUIRED

39.283123

60

7) HEAT LOAD AROUND EXTRACT COLUMN REBOILER

SHELL SIDE: HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

233198.02 243 Cp=

0.5755

32611.9269 37903.2158 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

5216.4966

233198.02 246 Cp=

0.64672

37100.2006 43119.7124

TUBE SIDE: OIL

IN

TEMPERATURE (DEG C)

300 Q=INT(M*Cp*DT) INT(Cp*dT)

137.96971

88

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

136112.39

244

8) HEAT LOAD AROUND EXTRACT COLUMN CONDENSER

HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

67611.87 101 Cp=

1.1686

7980.13436 9274.91209 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

AIR

IN

TEMPERATURE (DEG C)

7604.2765

67611.87 54 Cp=

0.3937

1437.41483 1670.63556

35 Q=INT(M*Cp*DT) INT(Cp*dT)

25.366928

MASS FLOW

OUT

TEMPERATURE (DEG C)

(KG/HR)

1079176.6

HP REQIRED

40.089367

60

89

BACKEND 1) HEAT LOAD AROUN PACOL CHARGE HEATER

HC

IN

MASS FLOW (KG/HR)

106016.6

TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

387

Cp=

0.8902

36523.503 42449.446 CHANGE IN ENTHALPY

OUT

MASS FLOW (KG/HR)

11507.724

Cp=

0.893675

106016.6

TEMPERATURE (DEG C) ENTHALPY (CAL/HR)

(KW)

490 46424.749

( KILOWATT)

53957.17

FUEL

MASS FLOW

OIL

Q= MASS*CALORIFIC VALUE

(KG/HR)

1039.6245

2) HEAT LOAD AROUND DEFINE SEPARATOR PUMP AROUND COOLER

HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

171821.19 174

Cp=

0.49546

14812.712 17216.076 CHANGE IN ENTHALPY

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C)

(KW)

13485.381

Cp=

0.339665

171821.19 55

90

ENTHALPY (CAL/HR) ( KILOWATT)

AIR

IN

TEMPERATURE (DEG C)

3209.8905 3730.6956

35 Q=INT(M*Cp*DT) INT(Cp*DT)

45.734651

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

1061500.8

80 HP REQUIRED

39.432745

3)HEAT LOAD AROUND DEFINE SEPARATOR PUMP AROUND TRIM COOLER

SHELL SIDE: HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

171821.19 55

Cp=

0.3396

3209.8905 3730.6956 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

1454.1247

171821.19 40

Cp=

0.285

1958.7616 2276.5709

91

TUBE SIDE: WATER IN

TEMPERAUTRE (DEG C)

25 Q=INT(M*Cp*DT) INT(Cp*DT)

14.440125

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

362521.04

33

4) HEAT LOAD AROUND DEFINE CHARGE HEATER

SHELL SIDE: HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

86987.25 175

Cp=

0.49485

7532.9871 8755.2152 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

3028.0389

86987.25 220

Cp=

0.52977

10138.312 11783.254

TUBE SIDE: OIL

IN

TEMPERAUTRE (DEG C)

300 Q=INT(M*Cp*DT) INT(Cp*DT)

114.20402

92

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

95451.455

254

5) HEAT LOAD AROUND PRODUCT STRIPPER REBOILER

SHELL SIDE: HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

80237.5 270

Cp=

0.3698

8011.3934 9311.2429 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

6212.7549

80237.5 278

Cp=

0.5988

13356.848 15523.998

TUBE SIDE: OIL

IN

TEMPERAUTRE (DEG C)

300 Q=INT(M*Cp*DT) INT(Cp*DT)

85.187562

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

262549.1

266

93

6) HEAT LOAD AROUND PRODUCT STRIPPER CONDENSER

HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

18019.75 173

Cp=

0.9094

2834.9788 3294.9544 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

AIR

IN

TEMPERAUTRE (DEG C)

2562.7712

18019.75 80

Cp=

0.437

629.97046 732.18324

35 Q=INT(M*Cp*DT) INT(Cp*DT)

25.366928

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

363700.97

60 HP REQUIRED

13.510802

7) HEAT LOAD AROUND DESORBENT HEATER

HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

26967.1 102

Cp=

0.3426

942.3707 1095.2705

94

CHANGE IN ENTHALPY (KW) OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

421.43146

26967.1 130

Cp=

0.37224

1304.9703 1516.7019

MASS FLOW MP STEAM

Q=M * λ

(KG/HR)

706.52351

8) HEAT LOAD AROUND DE-PENTANIZER COLUMN REBOILER

HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

91417.95 128

Cp=

0.3795

4440.7183 5161.2254 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

3095.5973

91417.95 129

Cp=

0.60241

7104.1703 8256.8227

MASS FLOW MP STEAM

Q=M * λ

(KG/HR)

5189.7223

95

9) HEAT LOAD AROUND DEPENTANIZER COLUMN CONDENSER

HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

46035 73

Cp=

0.5201

1747.8247 2031.4094 CHANGE IN ENTHALPY

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

AIR

IN

TEMPERATURE (DEG C)

(KW)

420.682

Cp=

0.4363

46035 69 1385.8699 1610.7274

35 Q=INT(M*Cp*DT) INT(Cp*DT)

25.366928

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

59701.955

60 HP REQUIRED

2.2178146

10) HEAT LOAD AROUND DESORBENT COLUMN REBOILER

SHELL SIDE: HC

IN

MASS FLOW (KG/HR)

102805.2 96

TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

223

Cp=

0.4634

10623.704 12347.402 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

2622.1061

102805.2 224

Cp=

0.5593

12879.764 14969.508

TUBE SIDE: OIL

IN

TEMPERAUTRE (DEG C)

300 Q=INT(M*Cp*DT) INT(Cp*DT)

123.75542

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

76276.109

250

11) HEAT LOAD AROUND DESORBENT COLUMN CONDENSER

HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

26806.62 86

Cp=

1.4032

3234.8942 3759.7562 CHANGE IN ENTHALPY (KW)

3116.444 97

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

AIR

IN

TEMPERATURE (DEG C)

26806.62 66

Cp=

0.31285

553.50577 643.31215

35 Q=INT(M*Cp*DT) INT(Cp*DT)

25.366928

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

442276.6

60 HP REQUIRED

16.429738

12) HEAT LOAD AROUND BENZENE COLUMN REBOILER

SHELL SIDE: HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

99901.52 193

Cp=

0.4938

9520.9545 11065.73 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

2744.4587

99901.52 200

Cp=

0.5947

11882.287 13810.189

98

TUBE SIDE: OIL

IN

TEMPERAUTRE (DEG C)

300 Q=INT(M*Cp*DT) INT(Cp*DT)

107.00091

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

92336.147

257

13) HEAT LOAD AROUND BENZENE COLUMN CONDENSER

HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

108242.46 100

Cp=

1.2499

13529.225 15724.343 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

AIR

IN

TEMPERATURE (DEG C)

13808.656

108242.46 54

Cp=

0.28199

1648.2577 1915.6877

35 Q=INT(M*Cp*DT) INT(Cp*DT)

45.734651

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

1086947.4

80 99

HP REQUIRED

40.378037

14) HEAT LOAD AROUND PARAFFIN COLUMN REBOILER

SHELL SIDE: HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

131438.31 214

Cp=

0.3448

9698.4649 11272.042 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

2841.6889

131438.31 220

Cp=

0.41995

12143.454 14113.731

TUBE SIDE: OIL

IN

TEMPERAUTRE (DEG C)

300 Q=INT(M*Cp*DT) INT(Cp*DT)

137.96971

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

74147.288

244

15) HEAT LOAD AROUND PARAFFIN COLUMN OVREHEAD COOLER 100

A) FIN FAN COOLER

HC

IN

MASS FLOW (KG/HR)

210704.56

TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

128

Cp=

0.4542

12249.857 14237.398 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR)

210704.56

TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

AIR

IN

8416.2072

65

Cp=

0.3657

5008.5527 5821.191

TEMPERATURE (DEG C)

35 Q=INT(M*Cp*DT) INT(Cp*DT)

25.366928

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

1194403.4

60 HP REQUIRED

44.369825

B) COOLING WATER CONDENSER

SHELL SIDE: HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

210704.56 65

Cp=

0.3657

5008.5527 5821.191 101

CHANGE IN ENTHALPY (KW) OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

2515.1571

210704.56 45

Cp=

0.3

2844.5116 3306.0339

TUBE SIDE: WATER IN

TEMPERAUTRE (DEG C)

25 Q=INT(M*Cp*DT) INT(Cp*DT)

14.440125

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

627042.07

33

16) HEAT LOAD AROUND RERUN COLUMN REBOILER

SHELL SIDE: HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

73950.252 216

Cp=

0.3858

6162.4816 7162.3449 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C)

2748.6133

73950.252 225

Cp=

0.5125 102

ENTHALPY (CAL/HR) ( KILOWATT)

8527.3884 9910.9582

TUBE SIDE: OIL

IN

TEMPERAUTRE (DEG C)

300 Q=INT(M*Cp*DT) INT(Cp*DT)

99.763823

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

99184.329

260

17) HEAT LOAD AROUND PARAFFIN COLUMN OVREHEAD COOLER

A) FIN FAN COOLER

HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

71861.77 193

Cp=

0.47

6518.5812 7576.2217 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

AIR

IN

TEMPERATURE (DEG C)

7239.6307

71861.77 65

Cp=

0.062

289.60293 336.59104

35 103

Q=INT(M*Cp*DT) INT(Cp*DT)

25.366928

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

1027427.2

60 HP REQUIRED

38.166972

B) COOLING WATER CONDENSER

SHELL SIDE: HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

71861.77 65

Cp=

0.47

2195.3771 2551.5773 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

2318.5527

71861.77 45

Cp=

0.062

200.49434 233.02457

TUBE SIDE: WATER IN

TEMPERAUTRE (DEG C)

25 Q=INT(M*Cp*DT) INT(Cp*DT)

12.632765

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

660725.48

32 104

18) HEAT LOAD AROUND RECYCLE COLUMN REBOILER

SHELL SIDE: HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

98041.975 230

Cp=

0.4706

10611.867 12333.644 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

3834.8382

98041.975 237

Cp=

0.5987

13911.362 16168.482

TUBE SIDE: OIL

IN

TEMPERAUTRE (DEG C)

300 Q=INT(M*Cp*DT) INT(Cp*DT)

123.75542

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

111554.04

250

19)HEAT LOAD AROUND RECYCLE COLUMN OVERHEAD COOLER

105

SHELL SIDE: HC

IN

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

6868.9 212

Cp=

0.3785

551.17427 640.60236 CHANGE IN ENTHALPY (KW)

OUT

MASS FLOW (KG/HR) TEMPERATURE (DEG C) ENTHALPY (CAL/HR) ( KILOWATT)

536.59888

6868.9 45

Cp=

0.2895

89.484595 104.00348

TUBE SIDE: WATER IN

TEMPERAUTRE (DEG C)

25 Q=INT(M*Cp*DT) INT(Cp*DT)

9.0200549

MASS FLOW (KG/HR) OUT

TEMPERATURE (DEG C)

214162.33

30

106

SUMMARY TABLE:

UTILITY 1) HOT OIL (KG/HR)

1385992.709

2)COOLING WATER (KG/HR)

1864450.907

3) MP STEAM (KG/HR)

5896.245852

4) FUEL OIL (KG/HR)

1039.624493

5) POWER FOR FANS (HP)

539.2241054

107

CHAPTER 5: UTILITIES

108

The Utility section consist 11 units: 5.1 Hydrogen Plant 5.1.1 Introduction This plant is designed to produce high purity of hydrogen gas from liquid naphtha. Catalytic reforming of Naphtha produces hydrogen and superheated steam at elevated temperature in vertical cylinder reformer furnace. Mainly Hydrogen is produced in a Shift converter by the reaction of carbon Monoxide and steam. Impurities: carbon Monoxide, carbon dioxide, methane and water. These impurities are removed by unique adsorption system and producing ultra-pure hydrogen.

5.1.2 Process flow diagram

Figure 5.1 Process flow diagram of H2 plant

5.1.3 Process description The liquid naphtha which is the feed for production of H2 is stored in a buffer vessel at a temperature 210C and pressure of 2.04 kg/cm2.From here, naphtha is pumped from 2.04 kg/cm2 up to 27.4 kg/cm2 with horizontal sun dyne pump. The naphtha is sent to kettle type vaporizer through a filter at 2680C where it exchanges heat with fuel gas flowing in the tube side. When 109

the level in the vaporizer goes to 40%, the pump starts and when it reaches 70%, the pump automatically stops. Now the naphtha from the vaporizer enters into the heater where it exchanges heat with reformer gas on tube side and temperature rises to 3990C. Before it enters the heater, it is mixed with a side stream of H2 from the compressor. Heating is done to remove any kind of moisture present in naphtha. During startup of the plant, naphtha fuel is directly taken from the buffer vessel. So it is very important to keep a check on the moisture getting accumulated in it. During normal operation, the fuel is taken from the bottom of the feed vaporizer in order to remove hydrocarbon which is accumulated. From here, feed flows through hydro-treater. Here, in presence of COMOX (cobalt-molybdenum oxide) catalyst, any olefins present in the feed react with the hydrogen to form saturated hydrocarbons and sulphur present in it reacts with hydrogen forming hydrogen sulphide. A chlorine guard is kept at the top of the hydro-treater to remove any Cl present in it. The feed gas then flows through the desulphurizer, where in the presence of ZnO catalyst and at temperature of 300-4000C H2S formed in hydro-treater is absorbed by the following reaction: ZnO+H2S → ZnS+H2O Temperature is the only parameter that can be controlled to improve the performance of the units. The efficiency of the hydro-treater and desulphurizer units increases greatly as the flow is decreased or its operating pressure is increased. The feed gas then enters the reformer which is vertical cylinder balanced draft type with 20 tubes and 3 burners. The tubes are arranged in a circle near the insulated refractory wall. Naphtha and vent gases are used as fuel. Burner design draft is -6.35 mmwc. Air is supplied from the air pre-heater. The burners should be operated to provide a flame which is very short and thin. Flow in the tubes and the firings of the furnace are both upward. The furnace should be fired such that the flame should not impinge on the catalyst tubes. Here, the feed reacts with superheated steam coming from super heater at a temperature of 500-8750C. The reaction takes place in presence of Ni catalyst to form mixture of water vapor, CO, CO2, CH4 and H2. CmHn + mH2O → (n/2 + m) H2 + mCO The reforming reaction is highly endothermic reaction. In addition to the reforming reaction, a partial water shift reaction also occurs in the reformer. CO + H2O → CO2+H2

110

The hot process gas exiting the reformer flows through the Reformer Effluent Steam generator at around 800-8750C. The gas leaving the reformer furnace is used to superheat the process steam before it enters the reformer tubes. Flue gas is also used to produce steam and to heat the combustion air before it enters the reformer tubes. In the reformer effluent steam generator, the steam is produced and temperature is controlled down to 3570C.The flue gases from the reformer goes to flue gas steam generator and then into the APH where it heats the air blown in by the FD fan and this air is sent into the reformer furnace for burning. The remaining flue gas enters into the economizer where again it exchanges heat with liquid and then the ID fan takes the flue gases into the stack. The gas then enters the shift converter wherein presence of copper promoted iron oxide catalyst the water gas shift reaction converts the CO to H2 and CO2. The reaction being exothermic, the temperature increases by around 40 to 500C.The shift conversion reaction depends on temperature, pressure, steam/carbon ratio and fluorite. The higher the temperature, the faster the reaction rate. The normal pressure drop is very low in the converter which can increase due to fouling, catalyst breakdown etc. The shift converter catalyst is very sensitive to sulfur poisoning. This gas flows through heater where it exchanges heat with the naphtha and hydrogen mixture coming from vaporizer. The temperature is reduced to 3880C.This gas then goes to vaporizer where temperature further reduces to 3200C. The process gas then flows through the Shift Effluent Steam Generator; through the boiler feed water (BFW) heat exchanger where it will exchange heat with mixture of BFW and DM water. Then it goes into de-aerator exchanger where it again exchanges heat with water on tube side. It is further cooled in a cooler to a temperature of 380C with the help of water coming from cooling tower. The cool gas is sent to cold condenser separator (CCS) where the process gas is separated from top and sent to pressure swing Adsorbers (PSA) which consists of three layers of adsorbent. The liquid is separated from the bottom and sent to de-aerator exchanger after making up with the boiler feed water. In de-aerator exchanger, the liquid exchanges heat with process gas. This liquid is sent into the de-aerator where a side stream from the steam drum also enters. In the de-aerator, the liquid is treated with hydrazine to remove O2. This hydrazine is prepared in a low pressure vessel as well as in a high pressure vessel. The hydrazine from HP vessel is sent to the BFW exchanger along with the bottom liquid from de-aerator where it exchanges heat with process gas.

111

This liquid enters into the economizer where it will exchange heat with the flue gases and this hot liquid goes into the steam drum. In PSA, there are four adsorption beds and one will remain in run mode whereas remaining three in regeneration condition. Granular adsorbents in the adsorber vessel trap all the impurities. This system uses alumina for bulk water, activated carbon for bulk CO2 and methane removal and molecular sieve for CO removal and purity improvement. After purification by the Adsorption system, product hydrogen is available at 20.4 kg/cm2 the pure hydrogen is sent to different units wherever required. During the regeneration step, the impurities are cleaned from the adsorbent by the following steps: (a) The adsorbed is depressurized to a lower pressure to reject some of the impurities. (b) The adsorbent is purged with hydrogen to remove remaining impurities. (c) The adsorbed is re pressurized to adsorption pressure and is again ready to purify the feed Gas. (d) The impurities from the bottom are taken into the vent drum from where it is sent to Reformer to be used as fuel for burning.

5.2 Nitrogen plant 5.2.1 Introduction Nitrogen is produced using Pressure Swing Adsorption system. PSA N2 generators are based on well-proven technology using Carbon Molecular Sieves. Carbon Molecular Sieves (CMS) are adsorbent beds having an infinite number of pores, which are smaller than ordinary Molecular Sieves. When CMS are used in PSA (Pressure Swing Adsorbtion) process, Oxygen molecules having a smaller diameter than Nitrogen molecules are absorbed into the pores. So the Nitrogen is recovered to a high degree. Adsorption bed is made of CMS, Alumina balls, Silica gel & coconut jar.

5.2.2Process flow description Plant air is pre-filtered & sent to Pressure Swing Adsorption system. It has two adsorbent beds containing carbon molecular sieves. One of the beds is in loaded condition while other is being depressurized. The adsorption & desorption cycle is of 65 sec. The absorber uses Carbon Molecular Sieves (CMS) for adsorption. CMS have infinite no. of very small diameter pores which are smaller than ordinary molecular sieves. As O2 has a smaller diameter it gets adsorbed while nitrogen passes through product pipeline. 112

During depressurization, the adsorbed gases are desorbed from the molecular sieves. The pressurization and depressurization of beds are alternatively adjusted using charged over valves. The N2 obtained is 99% pure. It is an automated continuous process. It produces 500 m3/hr of N2 having 6.5 to 7.5 kg/cm2 pressure & 40 °C temperature. Nitrogen uses in the plant are: For vessel purging, for blanketing the buffer vessel, for blanketing the storage tanks. In case of emergency it can be used as replacement for instrument air.

5.3 Hot Oil Heater 5.3.1 Introduction In the production of LAB, heat has to be supplied to the distillation column operation as well as in other heat exchangers for heating fluids. For this purpose hot oil or steam are used as heating medium. In this plant there are two hot oil heaters since one was not sufficient enough because of the increasing demand of heat duty. Hot oil heater is balanced draft furnace in which induced draft (I.D) fan and forced draft (F.D.) fan both are provided. It consists of two zones: (1) Convection zone (2) Radiation zone In convection zone 14 tubes are provided where as in radiation zone 13 tubes are provided. There are twenty burners for burning the fuel in which 16 burners are burning on fuel gas, two burners can run on fuel oil and two burners can run on light oil. An automatic spark generator is also provided in every burner. Steam is used for atomizing the fuel oil and LPG. It is also used as pilot gas which is provided in all burners for combustion. It is also used for removing the carbon deposited on the surface of the tubes. Preheated air is provided for different purposes: Primary air: For initiation and stabilization of oil flame. Secondary air: To provide high temperature and to maintain the size and Shape of flame. It is necessary to preheat the air to increase the efficiency of HOH and for heat recovery. In APH, from tube side, air is passed and from shell side flue gases of temperature approximately 400 C is passed and air is heated up to 260 C temperature. In the bottom of the

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APH, the tube is coated with glass to prevent corrosion of tube due to sulphur impurities present in flue gas.

Process flow diagram

Figure 5.3 Process flow diagram of Hot Oil Hea

5.3.3 Process flow description Hot oil from various parts of front end and back end is sent to the hot oil surge drum at a temperature of 250-2600C. In surge drum, hot oil is stored at a pressure of 1.5 kg / cm2.From the surge drum, the hot oil is pumped through the header of the heater at a pressure of 10.5 kg/cm2 and allowed to enter at the convection zone. In the convection zone, the fluid gets heated by the flue gases. This fluid then enters into the radiation zone where it gets heated by radiation. Hot oil from the heater is sent to the ring header from where hot oil having temperature and pressure of 305 0C and 8 kg/cm2 respectively to the front end and back end according to requirements. Air is preheated in the APH which is obtained by F.D. fan. Air passes through the shell side of the APH and heating it up to 2600C approximately. Such preheated air is entered in the heater. The flue gases from APH are sent to chimney by I.D. fan.

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5.4 Cooling tower 5.4.1 Introduction The basic purpose of the cooling tower is that it gives cold water for plant requirement. Here induced draft cooling tower is used to supply cold water in all parts of plant. It works on principle of evaporative cooling. Here mass transfer is taking place. Heat which is evolved in this operation is sensible heat & latent heat.

Figure 5.4 Diagram of cooling tower An induced draft counter current cooling tower is used to supply cooling water for entire plant. It contains 4 cells of 800 m3/ hr capacity with a common bottom basin to collect water. Each cell has an induced fan to induce 543600 m3/hr capacity of air. 4 pumps of capacity 800 m3 /hr are provided for circulating water. 2 emergency pumps of capacity 3200 m 3/hr are also provided. Total cooling water consumption is 2673 m3/hr. 19.7% excess capacity is also available. Cooling water is used in, Heat Exchangers, Pumps, Compressors, Sample coolers, Utility points. The cooling water operating conditions are: Supply Pressure

4kg/cm2

Return Pressure

2kg/cm2

Supply temperature

33°C

Return temperature

25-26°C

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5.4.2 Working The hot water coming from plant is pumped from bottom to individual cells. The hot water is charged into cooling tower from the nozzles at top. Induced draft fans at the top suck air into the cooling tower from bottom. Thus air flows counter current to water & water is cooled. A common basin is provided at the bottom for collection of water. To increase heat transfer distributor plates are used. Maintaining the quality of circulating cooling water is very important. In order to avoid scale formation on tubes of exchangers, acid (99%H2SO4) is injected through dosing pump from dosing tank into the water basin. Chlorine is also injected to prevent algae formation.TDS & TSS of water is checked as they increase hardness. When TDS & TSS quantities increase considerably, side steam is taken out which is sent to sand filter for removing TSS & TDS. Also de-mineralized water is partly added, as make up water, in order to maintain level in water basin.

5.5 D.M.Water plant 5.5.1 Introduction The main purpose of De-Mineralized water plant is to get pure water in order to prevent corrosion problems in boilers, Exchangers, etc. The source of water for plant is Mahi River.

5.5.2 Process flow diagram

Figure 5.5 Process flow diagram of D.M water plant

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5.5.3 Process description Water from river is pumped into Hypochlorite tank where sodium hypochlorite [NaOCl] is added to maintain chlorine levels in order to arrest algae growth. Then water is sent to Multi Grade Filter (MGF). Here, turbidity is removed using sand and gravel. Inlet water turbidity is 500 ppm while outlet water turbidity is 30-40 ppm. MCF is regenerated by water backwash. The MCF outlet is used as drinking water, Water for demineralization. Water for demineralization is sent to Activated Carbon Filter (ACF) to remove colour and smell with the help of activated carbon. It is then sent to Layer Bed Cation (LBC) Unit. This unit uses resin to remove cations like Na, Ca, Mg, etc. by replacing them with H ion. This resin is regenerated using HCl. The unit contains weak and strong acidic cation resin with the former forming the upper layer and the later being the heavier forms the lower layer. The upper layer removes the alkalinity associated with hardness in raw water and lower layer removes the remaining alkalinity. The de-cationised water is fed to Degasser tower (DGT) where water is sprayed form top and draft of air provided by the blower. This removes free carbon dioxide and degassed water is collected in Degassed water tank. The water is then pumped to Weak Basic Anion (WBA) Unit for removal of anions like Cl, SO4, NO3, etc. using resin before being fed to Strong Basic Anion (SBA) units. Here, anions remaining in trace amounts and silica are removed producing de-mineralized water. SBA & WBA resins are regenerated using caustic. The DM water has following specification:

Table 5.1 Water specifications for DM water plant Parameter

Treated water

Raw water

Turbidity mg/lit