Manufacture of Sodium Dichromate

PROJECT REPORT on

MANUFACTURE OF SODIUM DICHROMATE submitted in partial fulfillment of the requirements for the award of the degree of

BACHELOR OF TECHNOLOGY (CHEMICAL ENGINEERING) of

UNIVERSITY OF MADRAS by

R. JANAKIRAMAN (9002122) L.M. SHIVA SHANKAR (9002129) S. NARESH KUMAR (9090365) under the guidance of

Dr. R. KARTHIKEYAN, Ph.D., (Professor, Department of Chemical Engineering)

APRIL 2004

DEPARTMENT OF CHEMICAL ENGINEERING

S.R.M. ENGINEERING COLLEGE S.R.M. Nagar, Kattankulathur, Kancheepuram District - 603 203.

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BONAFIDE CERTIFICATE

MANUFACTUREOF SODIUM DICHROMATEt&a

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Bachelor

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of Technology

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Submitted for university examination held in April 2004 at S.R.M. Engineering College, Kattankulathur.

Internal Examiner

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ACKNOWLEDGEMENT

We are extremely thankful to Dr. R.Venkatramani, Principal, S.R.M. Engineering College, for permitting us to work on this project. We would like to thank Dr. R. Kannappan, Professor and Head, Department of Chemical Engineering for allowing us to work on this project, and for providing us with support and guidance. Above all, we would like to thank our esteemed Dr. Karthikeyan, Professor, Department of Chemical Engineering, for his encouragement and guidance at all stages of this project. We extend our sincere thanks to all the staff members of the Chemical Engineering Department for their assistance and support.

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ABSTRACT This project deals with the study of the manufacturing process of sodium dichromate from chromite ore. A detailed study is made on the design of equipment. The materials of construction and the plant location are studied in detail. The ultimate cost analysis is done and the payback period is also calculated. Finally, the safety and health factors are also concerned for the effective use of the material. The project is feasible for the large-scale operations and it is very effective in reality.

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CONTENTS

INTRODUCTION

1

PROPERTIES

3

APPLICATIONS

5

PROCESS DESCRIPTION

8

MATERIAL BALANCE

12

ENERGY BALANCE

17

DESIGN

27

PROCESS CONTROL

34

MATERIALS OF CONSTRUCTION

37

SAFETY AND HEALTH FACTORS

41

PLANT LAYOUT

47

ECONOMICS

57

CONCLUSION

65

BIBLIOGRAPHY

66

INTRODUCTION

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INTRODUCTION Chromium compounds Sodium Dichromate is an extraordinarily versatile member of the chromium compounds. Chromium, Cr, also loosely called chrome, is the twenty-first element in relative abundance with respect to the earth's crust, yet it is the seventh most abundant element and overall Cr is concentrated in the earth's core and mantle. Chromium was first isolated and identified as a metal in 1789 by Vauquelin who was working with a rare mineral, Siberian red lead. The name chromium comes from Greek word chroma meaning color and resulted from with wide variety of brilliant colors displayed by compounds of the metal. Basic chromium sulfate. was used for tanning hides. The reaction of chromium and collagen raises the hydrothermal stability of the leather (qv) and renders it resistant to bacterial attack. The most important applications of chromium are alloying elements, improved oxidation resistance and hardenability, and the superior corrosion resistance.

Occurrence and Mining Chromite deposits occur in olivine and pyroxene type rocks and derivatives. Geologically these appear in stratiform deposits several feet thick covering a very wide area and are usually mined by underground methods in such countries as South Africa, Zimbabwe, India, and Finland. Podiform deposits, Le., isolated lenticular, tabular, or pod-shaped bodies ranging in size from a kilogram to several million tons are mined by both surface and underground methods in Russia and Albania, depending on size and occurrence, but these

1

account for only about 10% of the world's chromium ore resources. Lateritic and placer deposits are not commercially significant. However, fines or lower grades ores can be effectively concentrated by gravity separation methods yielding products as high as 50% Cr203 with the Cr: Fe ratio of the original ore usually unchanged. Decreasing world supplies of high grade lumpy ore and increasing availability of high grades fines and concentrates have led to an increased use of three agglomeration methods :I) briquetting with a binder; 2)production of an oxide pellet by kiln firing; 3) production of a prereduced pellet by furnace treatment.

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PROPERTIES

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Properties of Sodium Dichromate: Physical and Chemical:

Formula:

Appearance: Orange-red crystals or granules. Odor: Odorless. Solubility: Very soluble in water, insoluble in alcohol. Specific Gravity: 2.35 at 25°C (77OP) pH: 3.5(1% solution) 4.0(10% solution) % Volatiles by volume at 210 C (700 F):

o Boiling point:

400° C (752° F)

Melting Point: 357°C (675°F), decomposed at above 400° C

3

Vapor Density (Air=1): 10 Vapor Pressure (mm Hg): o at 20°C (68°P)

Evaporation Rate: No Information found. Density: 2.35 at 13°C Stability: Under normal use conditions, this solution is stable. Conditions: To avoid Sodium dichromate is mildly oxidizing in solution but becomes

strongly oxidizing in strong acid solution. To avoid contact with organic materials, oils, greases and any oxidisable materials. May react with strong alkalis or acids emitting heat. Thermal Decomposition: Decomposition ofNa2Cr207 (anhydrous salt) starts at 400°C Hazardous Decomposition: Thermal decomposition may produce chromic oxide (Cr203) or other oxides.

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APPLICATIONS

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APPLICATIONS OF SODIUM DICHROMATE Metal finishing Corrosion Control: They are used as sealers or after-dips to improve the corrosion resistance of various coatings on metals. They are used in etching and bright-dipping of copper and its alloys. In addition to this, they are used to inhibit metal corrosion in recirculating water systems. Furthermore,

it is used as corrosion inhibitor for cooling systems In

locomotive diesels and automobiles.

Pigments: An excess of finely ground ammonium sulfate is mixed with sodium

dichromate, and the dry mixture is heated to form chrome oxide and sodium sulfate. It is used as an oxidizing agent in manufacturing of dyes, many other synthetic chemicals, and ink. It is used in the manufacturing of chromic acid and chrome pigments.

Leather Tanning and Textiles: Chrome tanning is the most important tannage for all hides except heavy cattle hides, which are usually fresh vegetable, tanned. In heavy shoe uppers and soles, a chrome tanned leather is frequently given a vegetable retain to produce chrome retan leather. 5

It is used as an oxidant and source of chromium in textile industry to dye wool and synthetics with mordent acid dyes, oxidized vat dyes and indigo sol dyes on wool.

Wood Preservation: It is used in fire-retardant formulations where their function is to prevent leaching of the fire retardant from the wood and corrosion of the equipment employed. After impregnation of wood the sodium dichromate compound used in formulation, react with the wood extractives and the others preservatives salts to produce relatively insoluble complexes from which preservatives leaches only very slowly. Miscellaneous

Uses:

It is used in petroleum and natural gas industries for drilling muds. It is used in pharmaceuticals like Brufen drugs. It is used in the manufacturing of saccharine. It is used as a ferromagnetic material in high fidelity magnetic tapes. Used for hardening gelatin. Further it used in electric batteries, bleaching fats, oil sponges and resins.

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Overall percentage distribution of sodium dichromate consumption: Wood Preservation

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38 %

Metal Finishing

15 %

Leather tanning

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10 %

Pigment

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8%

Chemical Manufacturing

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8%

Oil Drilling Muds Textile Magnetic Tapes

4% 3% 2%

Other uses (Catalyst, photography, Etc.,) -

11 %

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PROCESS FLOW SHEET AND DETAILED PROCESS DESCRIPTION

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ACIDIFICATION

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ORE

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ROTARY

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TANK

KILN

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SULFURIC ACID

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ASH

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ROTARY FILTER

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SODIUM SULPHATE

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TRIPLE

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EFFECT EVAPORATOR

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CRYSTALLIZER

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WATER

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DRIER

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!_=~~=~~~~U:ATE TO ACIDIFICATION TANK

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SODIUM 01 CHROMATE STORAGE

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CENTRIFUGE

Fig. 1 FLOW DIAGRAM OF MANUFACTURING

OF SOCIlJM DICHROMATE

PROCESS DESCRIPTION Production of Sodium Dichromate Directly or via several intermediate stages, sodium dichromate is the starting material for the production of all chromium compounds and pure chromium metal. Sodium dichromate is made in a three-step process: 1) Alkaline roast of chromites under oxidizing conditions 2) Leaching, and 3) Conversion of sodium monochromate to sodium dichromate by means of acids.

Process Description The figure 1 gives a detailed process description of manufacturing of sodium dichromate.

Alkaline Roasting: A typical roast mixture contains 100 parts of ore, 60-75 parts of sodium carbonate, 0-100 parts of lime or dolomite, and 50-200 parts of inert materials. The components are first finely ground, then mixed, and fed into the furnace. Annular hearth furnaces or rotary kilns are commonly used in large plants today. 9

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We consider rotary kiln between the feed point and the reaction zone is used to heat the mixture. Shortly before the mix reaches the actual reaction zone, the soda melts and calcines. At this point the mixture cakes, and pellets or wreath-shaped cakes may be formed. If the furnace is operated inexpertly or the composition of the mixture is wrong, the kiln tube may get cleared by using an industrial gun. The hot exhaust gas from the rotary kiln can be used to preheat the burner air.

Leaching of the Roast After the oxidative process, the roast mixture of soluble salts and insoluble components. When the roast is extracted with hot water, a pH of 10.5-11.2 results. The pH is controlled by adding acids or carbonates so that all chromate dissolves, whereas the alkali- soluble impurities hydrolyze and form a readily filterable precipitate along with the iron hydroxide and the unchanged ore components. The roast is first cooled on a Fuller grate or in a cooling drum. Then it is either ground in a wet tube mill after addition of water or wash solution with carbonates or acids added, or it is dissolved in a stirred vessel. The insoluble residue is separated from the sodium chromate solution and thoroughly washed with a countercurrent of water. After removal of residual of aluminum hydroxide and other undissolved components in a final purification process, the concentration sodium chromate solution is acidified. 10

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Acidification The sodium chromate solution is converted into sodium dichromate solution by acidification with sulfuric acid. The reaction is: 2 Na2Cr04 + H2S04

> Na2Cr207 + Na2S04 + H20

Sulfuric Acid Acidification: Sulfuric acid is added to the concentrated sodium monochromate solution in an agitated vessel. The sodium dichromate solution is then concentrated in a continuous evaporation plant. Each liter of sodium dichromate solution yields 400-500 g of anhydrous sodium crystalline sodium sulfate. The sulfate is removed by centrifugation. The clear, dark-red sodium dichromate

solution contains 900-1200 g of Na2Cr207.2H20per liter and additional small amounts of sodium sulfate; it is dispatched in tanks. The solution is either used directly as an oxidizing agent or processed to yield dichromate crystals.

Crystallization For the purpose of crystallization the sodium dichromate solution is further concentrated and may, if necessary, be filtered while hot to remove additional sodium sulfate or sodium chromate. It is then slowly cooled to 3035° C with constant stirring to obtain orange-red crystals of Na2Cr207.2H20.The continuous vacuum crystallization is carried out to an increasing extent. The crystalline slurry is continuously separated from the mother liquor and dried. Precise control of the drying temperature is important because hydrated sodium dichromate is converted into anhydrous sodium dichromate above 84.6°C and, therefore, cakes if overheated.

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MATERIAL BALANCE

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MATERIAL BALANCE ROTARY KILN:

02 : 262.39kg/hr N2 : 863.69kg/hr

ORE : 1182.49kg/hr (Fecr204) Inert : 1182.65kg/hr

ORE : 308.27kg/hr (Fe2cr204) Na2cr04 :1265.3kg/hr Fe203 : 311.84 kg/hr Inert : 1182.65kglhr

ROTARY KILN

: 34361kg/hr :43.73kg/hr : 863.69kglhr

Na2c03 : 827.80kg/hr

EXTRACTOR:

Fecr204 : 308.2716kg/hr Na2cr04: 1265.13kg/hr Fe203 : 311.84kglhr Inert : 1182.65kg/hr

Na2cr04 : 1263.85kglhr H20 : l078.88kglhr LEACHING

H20

Fe2cr04 Na2cr04 Fe203 Inert

: l078.88kg/hr

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: 308.27kg/hr :1.27kg/hr : 311.84kglhr : 1182.65kglhr

ACIDIFIER:

Na2cr04 : 1263.85kglhr H2S04 : 344.09kglhr ACIDIFICATION H20

: 1085.90kglhr

Na2cr04 --'"-Na2cr207 Na2S04 H20

: 126.44kglhr : 919.92kglhr : 498.58kglhr : 1149.11kglhr

ROTARY FILTER:

Na2cr207 : 919.92kglhr Na2cr04 : 126.44kg1hr Na2S04 : 498.58kg1hr H20 : 1149.11kglhr

ROTARY FILTER

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Na2cr207 : 919.92kglhr Na2cr04 : 126.44kglhr Na2S04 : 262.31kglhr H20 : 1149.11kg1hr

EVAPORATOR:

Steam: 612.41kg/hr

Na2cr207 : 919.92kg1hr Na2cr04 : 126.44kg/hr Na2S04 : 262.31kg/hr H20 : 1149.11kg/hr

TRIPLE EFFECT EVAPORATOR

Na2cr207 : 919.92kg/hr Na2cr04 : 126.44kg/hr H20 : 536.69kg/hr

Steam: 118.25kg1hr

Na2cr207 : 919.92kg/hr Na2cr04 : 126.44kg1hr H20 : 536.69kg/hr

SINGLE EFFECT EVAPORATOR

]

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Na2cr207 : 919.92kg/hr H20 : 418.43kg/hr

CRYSTALLIZER:

Mother liquor : 876.33kg1hr Na2cr20, : 919.92kglhr H20 : 418.43kglhr

CRYSTALLIZER -"'- Crystals

: 462.033kglhr

CENTRIFUGE:

Water: 175.266kglhr

Mother liquor: 876.33kglhr

Mother liquor: 1027.27kglhr CENTRIFUGE

Crystals

: 462.033kglhr

Crystals

15

: 486.34kglhr

DRYER:

Vapour: 23.39kglhr

Na2cr207.2H20 : 462.03kg1hr (Crystals) H20 : 24.31kglhr

DRIER

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Na2cr207.2H20 : 462.03kg1hr (Crystals) H20 : O.92kg1hr

ENERGY BALANCE

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ENERGY BALANCE EVAPORATOR (Triple Effect Evaporator):

The evaporator used is a triple effect, forward feed short tube vertical evaporator. The pressure, temperature and overall heat transfer coefficient in each of the effects is given below: Overall difference in temperature is 28.64

~T1 = 7.28 °C ~T2 = 10.02 °C ~T3 = 11.34 °C

Effect- I

Effect -II

Effect- III

Sat. temperature of steam( oC )

133.9

126.62

116.6

Temperature drop (oC)

7.28

10.02

11.34

126.62

116.6

105.26

0

0

Latent Heat of steam(kCal/KgoC)

516.6

525.92

537.63

Enthalpy of vapor (kCal / Kg)

648.85

645.57

641.53

2.50

2.395

2.290

Quantity

Boiling point of solution (oC) Boiling point elevation (oC)

Specific Heat (kcal/Kg oC)

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0

The energy balance for the above system is as follows

I -Effect

516.6 S + (2557.8 x 2.5 x 30) = (87.4388 x 2.15 x 126.62) + [(2470.36 - E1) x 2.395 x 126.62] + (E1 x 648.85)

II - Effect

525.92 El + [(2470.3-E}) x 2.395 x 126.62] = (87.4388 x2.15 x 116.6) + [(2382.93-E}-E2) x 2.270 x 116.6] + (645.57 x E2)

III- Effect

537.63 E2 + [(2382.93

- E1-E2)x 2.270 x 116.6] = (87.4388 x 2.15x 116.6)

+ (1583.064 x 2.190 x 105.26)+ [641.53 x (712.4184 - E}- E2)]

Where E}, E2, E3 represent the quantity of water removed in each effect

For solving the equations we get E}= 225.3 Kg/hr E2= 347.5 Kg/hr E3= 139.92 Kg/hr S= 794.35 Kg/hr

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For First Effect

U)A)~T)

= S As

1200x Alx 7.81= 794.35x 516.6 A)= 46.97 m2

F or second Effect

U2A2~T2 = E)x HI 600 XA2 x 10.02= 225.3x525.92 A2= 19.71 m2

For Third Effect

U3A3~T3= E2xH2

350xA3xl1.34 = 347.5x537.63 A3=47.07

Since the area values are not the same we calculate the average to be 37.9 m2

New ~T is calculated by the formula

~T = (~T

old) X (AJAavg)

~TI= 9.19 °C ~T2= 9.38 °C ~T3= 10.07 °C

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T

Effect- I Effect -II

Quantity

Effect- III

Sat. temperature of steam( oC )

133.9

123.51

114.13

Temperature drop (oC)

9.19

9.38

10.07

123.51

114.13

104.06

0

0

516.6

534.40

537.63

642.45

640.62

638.76

2.50

2.405

2.355

Boiling point of solution (oC) Boiling point elevation (oC) Latent Heat of steam(Kcal/Kg oC) Enthalpy of vapor (Kcall Kg) Specific Heat (Kcal/Kg oC)

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0

Substituting the above values in the equation and solving for E., E2, E3 and S. We get the values to be E)= 229.3 Kg/hr E2= 356.3 Kg/hr E3= 126.3 Kg/hr S = 774.5 Kg/hr

And also solving for the area we get A)= 36.28 m2 A2= 33.78 m2 A3= 34.98 m2

The deviation in area is only within:l: 10%. Hence, we take the final area of the heating surface of each evaporator to be 40m2. 20

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5n!!:gv Balance Summary: Amount of steam required for the first effect = 774.5kg/hr Amount of water evaporated in the first effect = 229.3kg/hr Amount of water removed in second effect

= 356.3 kg/hr

Amount of water removed in third effect

= 126.3 kg/hr

Evaporator (Single Effect Evaporator):

Amount of sodium dichromate entering = 919.92 kg/hr Amount of sodium sulfate entering

= 126.45kg/hr

Amount of water entering

= 536.69 kg/hr

Heat associated with feed (Hr)

= m.Cp mix.L1T

m = Mass of feed Cp mix= Specific heat of mixture b.T = Temperature difference

Cp mix= 2.3 Kcal/ KgOC

Hr= 1583.06 X2.3 X30 = 109231.14 Kcal/ hr

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Heat with product (Hp)

= m.Cp mix.11T

m = Mass of the product Cpmix=Specific Heat of mixture 11T = Temperature Difference

Cp mix= 2.20 Kcal/KgOC

Hp = 1338.36 x 2.2 X 83.2 = 244973.41 Kcal/hr

Heat with crystal salt (He)

m = Mass of the crystal Cp= Specific Heat of salt 11T = Temperature Difference

Cp = 2.25 Kcal/KgOC

He = 126.45 x 2.25 x 83.2 = 23671.44 Kcal/hr

= S. As

Heat with steam (Hs) S = Amount steam supplied As = Latent heat of steam = 526.1 Kcal/Kg

Hs = 526.1 x S

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T

=m.He

Heat with vapor (Hv)

m = Mass of vapor He= Enthalpy of vapor Hv = 118.25 x 633.136 = 74868.33 Kcal/hr

S. As= 234282.046

S = 445.318 Kg/hr

The total amount steam supplied is 445.318 Kg/hr

Crystallizer: F.Hf =L.H1+C.A+Q Where, F= Amount of feed in Kg/hr Hf = Enthalpyof feed in Kcal/Kg L= Amount of mother liquor in Kg/hr H1=Enthalpy of mother liquor in Kcal/Kg C = Amount of crystals in Kg/hr A=Heat of Crystallization in Kcal/Kg Q = Amount of heat lost in the crystallizer Kcal/hr Q = F.Cp.~T + C. A

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T

'A= 125.53 Kcal/Kg Cp = 2 Kcal/KgOC F = 133.836 Kg/hr t1T= 80°C

Q = (133.836 x 2 x 80) + (462.03 x 125.53) = 272137.46 Kcal/hr

Dryer: Enthalpy of air inlet Hgi

Where, Cg = Specific heat of air

Cv = Specific Heat of water vapor HI = Moisture content of inlet air tl = Temperature of inlet air to = Datum temperature 'A= Latent Heat of Air

Hgi = (0.238 + (0.007 x 0.48)) x (135 - 0) + (597.7 x 0.007) = 36.77 Kcal/Kg of air

Enthalpy of air outlet (Hg2)

24

T

Where,

H2 = Moisture content exit air t2 = Temperature of exit air

Hg2 = (0.238 + (0.048 x H2)) x (80 - 0) + (597.7 x H2) = (19.04 + 636.1 H2) Kcal/Kg of dry air

Heat with solid at inlet

= F x Cp x /:). T = 486.3516 x 2.3 x 30 = 3358.26 Kcal/hr

Heat with solid at outlet

= p x Cp x /:). T = 462.96 x 2.3 x 65 = 69212.52 Kcal/hr

Overall Energy Balance

36.77 Gs + 3358.26 = 692.52 + 19.04 Gs+ (636.1x H2 x Gs)

17.73 Gs - (636.1 X H2 x Gs) = 35654.26

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Moisture Balance

Gs X (H2

- HI) = 23.3916

(Gs. H2) - 0.007Gs = 23.3196

By solving the two equations we get

Gs = 3782.99 Kg of dry air/hr

H2 = 0.013 Kg of water /Kg of dry air

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PROCESS EQUIPMENT DESIGN

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DESIGN OF EQUIPMENTS Evaporator (Triple Effect Evaporator):

The area of heating surface of each effect is approximately found to be 40m2. We assume, Outside diameter of tube = 0.05 m Inside diameter of tube

= 0.04 m

Length of tube

= 1.2m

Square pitch

= 0.075m

A= 1t.Do.L.n 40 = 1tx 0.05 x 1.2 x n n = 212.6 tubes = 216 (nearest number divisible by 4) Down take area (AD): Area of down take is taken = 75.1% of tube cross sectional area AD

= 1t/4 x D? x n x 0.751 = 0.2036 m2

Annular Area: Annular area = n x PT2 = 216 X .0752 = 1.4186 m2

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Area of the evaporator body = 1.1 x Total area = 1.1 x (1.4186 xO.2036) = 1.5605 m2

Area of evaporator = (n. D2)/4 1.5605= (n. D2)/4 D = 1.4096 m

Height of evaporator = 3 x L

=3.6m Design summary:

Diameter of evaporator = 1.4096 m Height of evaporator

= 3.6 m

Evaporator (single effect evaporator):

Q = S.As = A.U.ilT

Where, S = Amount of steam in Kg!hr As= Latent Heat of steam in Kcal/Kg A = Heat transfer area in m2 U = Overall Heat transfer co-efficient Kcal/hr m2 °C il T = Temperature difference between steam and vapor product in °C

Q = Amount of heat transfer in Kcal/hr 28

A= S.A/U.~T = (445.318 x 526.1)/(1000 x 36.8)

= 6.3664 m2 Assuming Triangular pitch = 0.075 m Length of tube = 1 m Outside diameter = 0.025 m Inside diameter

= 0.02 m

A=(nx1txDoxL) n = 6.3664/ (1tx 0.025 x 1) = 81.06 tubes Number of tubes = 90 (approx.) Annular Area: AA

= n x pi = 90 x 0.0752

= 0.5063 m2 Down take area: AD

= (1t/4 X Dj2 x n x 0.751) = 0.0212 m2

Total area = Annular area + Down take area = 0.5063 + 0.0212 =0.5275 m2

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Providing 10% reserve area Area of evaporator= 1.1 x total area = 1.1 x 0.5275 = 0.5802 m2 Diameter of Body = 0.8595 m Height of evaporator = 3 x L =3xl =3m

Design summary: Diameter of evaporator = 0.8595 m

Height of evaporator

=3 m

Crystallizer: Q = U.A.LlTIn

Where, Q = Amount of heat transfer in Kcallhr U = Overall Heat transfer co-efficient in Kcal/m2 hr °C A = Area of heating surface m2 LlTIn =

Logarithmic Mean temperature in °C

Cooling water required for crystallization enters at 20°C and leaves at 40°C. U

= 1300

Kcal/hr m2 °C

LlTln= [(80- 40) - (30 - 20)]/ In «80 - 40)/ (30 - 20))

= 21.6 °C 30

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Area = Q/ (U.~T1n)

= 272137.46/ (1300 x 21.6) = 9.6915 m2 The radius of crystallizer employed is 0.5 m

A = x.r.L L = 9.6915/ (0.5 x x) =6.2m Design Summary: Radius of crystallizer =0.5 m Length of crystallizer = 6.2 m

Dryer: Weight of bone dry solid (ms) = 486.3516x 0.95 = 462.034 KgIhr

Initial Moisture content (Xa)

= 5/ (100- 5) = 0.0526

Final Moisture content (Xb)

= 0.2/ (100 - 0.2) = 0.002

Given that, Tha= 135 °c

; Thb= 80 °c

Tsa=30 °c

; TSb= 65 °c

T w = 40 °c

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Where, T ha= Temperature of drying medium inlet in °c Thb = Temperature of

drying medium outlet in °c

T sa= Temperature of wet solid inlet in °c TSb

= Temperature of dry solid outlet in °c

T w = Wet Bulb temperature in °c

ilT = ((Tha- Tw)- (Thb- Tw))/ln ((Tha- Tw)/ (Thb- Tw))

= 37.12°c qT/ms = Cps (Tsb - Tsa) + Xa.CP1(Tw

-

Tsa)

+ (Xa -

(Tsb - Tw) + (Xa - Xb),Cpv .(Thb- Tw)

= 112.29 Kcal/Kg

qT= 112.29 Kcal/Kg x 462.034 Kg/hr = 5188.80 Kcal/hr

Csa= Cg + H).Cpv = 0.24 + (0.007 x 0.48) = 0.2434 Kg of water /Kg of dry air

mg = qT/ ((1 + H)).Csa' (Tha- Thb))

= 3848.60 Kg/hr Inlet moisture = 3848.60 x (1 + 0.007) = 3875.54 Kg/hr Gs= 3782.99 Kg/hr 32

---

Xb ).A. + Xb.CP1

Area of cross section = 3875.54/3782.99

= 1.024 m2

Diameter

= 1.14 m

Heat Balance:

Length of dryer = 7.45 m

LID Ratio = 7.45/1.14 =6.5 As LID ratio is within 4 and 10, the dimensions are acceptable.

Design Summary: Length of Dryer = 7.45 m Diameter of Dryer = 1.024m

33

- - -

PROCESS CONTROL

--

PROCESS CONTROL AND INTSTRUMENTATION The primary objectives of the designer when specifying instrumentation and control schemes are: 1. Safe plant operation: a) To keep the process variables within known safe operating limits. b) To detect dangerous situations as they develop and to provide alarms and automatic shutdown systems. c) To provide interlocks and alarms to prevent dangerous operating procedures.

2. Production rate: To achieve the desired product output.

3. Product Quality: To maintain the product composition within specified quality standards.

4. Cost: To operate at the lowest production cost, commensurate with other objectives.

34

-

-----

Evaporator Control: There are many variables that are to be controlled in an evaporator. Sum of them are: Pressure control:

The pressure of the steam that is being sent to each effect of the reactor should be maintained at the appropriate value. This is made possible by using many controllers which are available. Flow Control:

The flow rate of the feed and the steam entering each effect should be maintained at the appropriate level. Valves are available that helps us to maintain the flow rate at the required value.

REACTOR CONTROL

The schemes used for reactor control depend on the process and the type of reactor. If a reliable on-line analyzer is available, and the reactor dynamics are suitable, the product composition can be monitored continuously and the reactor conditions and feed flows controlled automatically to maintain the desired product composition and yield. More often, the operator is the final link in the control loop, adjusting the controller set points to maintain the product within specification, based on periodic laboratory analysis. 35

--

- --

Reactor temperature will normally be controlled by regulating the flow of heating or cooling medium. Pressure is usually held constant. Material balance control will be necessary to maintain the correct flow of reactants to the reactor and flow of products and unreacted materials from the reactor. Instrumentation:

Temperature Measurement:

The temperature-measuring element in a control system for a jacketed tank is generally thermocouple. The five most commonly used thermocouple are copper-constantan, iron-constatan, chromel-alumel, platinum-platinum 13% rhodium, platinum-platinum 10% rhodium. Flow rate Measurement:

The industrial devices for flow rate estimation are orifice meter, venturi meter, pitted tube, and rotometer. The piping system must be made of special corrosion resistant material meant corrosive fluids are used.

level Measurement:

The flow-shaft type is employed either in open vessels or in pressure vessels.

This method is suitable for a wide range of liquids and semi-liquids. Difficulties are sometimes encountered when the liquid deposits on the floor and when the liquid level is foaming or turbulent. 36

--

MATERIALS OF CONSTRUCTION

--

-

--

--

--1-

-

MATERIALS OF CONSTRUCTION In the fabrication of any chemical plant, the selection of materials of construction and appropriate techniques of fabrication playa vital role in success or failure of the plant. In plant in which severe operating conditions such as high temperature and pressure prevails, it is the duty of the chemical engineer to search for more dependable, more corrosion-resistant materials of construction. Fortunately, board range of materials is available for construction. This abundance of materials also possesses a problem for the engineers. It is not sufficient if the engineer selects the right material for construction; he should consider the economic aspects while selecting the material. Materials of construction may be divided into two general classifications of metals and non-metals.

Metals: Iron and Steel:

Although many materials have greater corrosion resistance than steel, cost aspects favor the use of iron and steel. As a result, they are often used as materials of construction when it is known that some corrosion will occur. If this done the presence iron salts in the product streams should anticipated and periodic replacements of the parts should be accounted for. 37

- - ---

Generally, cast iron and steel exhibit the same corrosion resistance. They are not suitable for use with dilute acids, but can be used with strong acids, since the protective coating of corrosion product forms on the metal surface. Carbon steel plates are used for a reactor which requires minimum properties, weldabililty, formability, and toughness. As well as some assurance that these properties will be uniform throughout. Stainless Steel:

There are more than hundred types of stainless steels. These materials are high chromium or high nickel-chromium alloys of iron containing small amounts of other essential constituents. They have excellent corrosion resistance and heat resistance properties. Stainless Steels show a great susceptibility to stress corrosion cracking. Stress with the small amount of alloys will result in the failure of metal wall. Copper and its Alloys:

Copper is relatively inexpensive, possesses fare mechanical strength, and can be fabricated easily into a wide variety of shapes. It is susceptible to oxidation. Copper is resistant to atmospheric moisture and oxygen because of protective coating composed primarily of copper oxide is formed on the surface. The oxide however is soluble in most acids, and thus copper should not be used when it must coming contact with acids in the presence of oxygen or oxidizing agents. The alloys of copper possess better qualities than copper alone and hence it is better to use alloys of copper for fabrication purposes. 38

--

Aluminum:

The lightness and relative ease of fabrication of aluminum and its alloys are factors that favor the use of these materials. Aluminum resists attack by acids because a surface of inert hydrated aluminum oxide is formed. This film occurs to surface and thus prevents corrosion.

Non-Metals: Glass, carbon, stoneware, bricks, rubber, plastics, and wood are common non-metals used as materials of construction. Many of the non-metals have low structural strength. Consequently, they are often used in the form of linings or coatings bonded to metal supports.

Glass and Glassed Steel:

Glass has excellent resistance and is subject to attack only by hydrofluoric acid and hot alkaline solutions. A main drawback is its brittleness and damaged by thermal shock. On the other hand, glassed combines corrosion of glass with working stress of steel.

Carbon and Graphite:

Impervious graphite is completely inert to all but the most oxidizing conditions. The disadvantage of this material is its low tensile strength.

39

---

Stoneware and Porcelain:

Materials of stoneware and porcelain are abort as resistance to acids and chemicals as glass, but with the advantage of greater strength. The disadvantage of this material is its poor thermal conductivity susceptibility to damage by thermal shock.

40

SAFETY AND HEALTH FACTORS

SAFETY HEALTH EFFECTS ACUTE EFFECTS SWALLOWED:

Toxic. Can cause systematic effects, liver & kidney failure may follow.

EYE: Exposure to low level concentrations may cause irritation or conjunctivitis. Over exposure will cause severe irritation & potential permanent eye damage. SKIN: Contact with cuts, scratches or abrasions can result in chromic sores & ulceration. May cause sensitization by skin contact. INHALED:

Dust or mist may cause irritation of the nasal septum & respiratory tract. Prolonged or repeated exposure may cause ulceration & perforation of the nasal septum.

41

--

-----

CHRONIC EFFECTS Prolonged or repeated exposure to Sodium Dichromate dust/mist may cause chronic eye irritation, skin sores & ulceration, also ulceration & perforation of the nasal septum.

FIRST AID SWALLOWED: If conscious, give water to drink. DO NOT INDUCE VOMITTING. If vomiting occurs spontaneously, keep airway clear & give more water. Seek medical attention immediately. EYE: Immediately irrigate with copious quantities of water for at least 15 minutes. Eyelids to be held open. Seek medical attention immediately. SKIN: Wash contaminated skin with of soap and water. Remove contaminated clothing and wash before re-use. Seek medical attention immediately. INHALED: Remove victim nom exposure

- avoid becoming a casualty.

Remove contaminated clothing and loosen remaining clothing. Allow patient to assume most comfortable position and keep warm. Keep at rest until fully recovered. If breathing laboured and patient cyanotic (blue) ensure airways are clear and have qualified person give oxygen through a face mask. If breathing has stopped, apply artificial respiration at once. In event of cardiac arrest, apply external cardiac massage. Seek medical attention immediately. 42

--

-- -

---

- --

-------

TOXICITY Oral LD50 (rat): 51 mglkg (both sexes) Inhalation LC50 (rat): 0.124 mg/l/4 hour (both sexes) Dermal LD50 (rabbit): 1000 mglkg 9both sexes) Irritant (4 hour) (rabbit skin): not a corrosive agent. EXPOSURE STANDARDS Maximum exposure limit of 0.05 mg. Cr/m3 8 Hour (TW A)

ENGINEERING CONTROLS Use in area with adequate ventilation.

PERSONAL PROTECTION Respiratory Protection: Selection of type should be based upon the likely workplace concentrations and the Maximum Exposure Limit of 0.05 mg Cr/m3.

Hands: Rubber or PVC gloves.

Eyes Protection: Eye close fitting chemical goggles. Eyewash facility should be in close proximityto work area. 43

-

-

Body Protection:

Overall or other protective clothing is supplied to the operator; it is recommended that this clothing be laundered at the end of the working period.

General Precautions:

Clean protective equipment should be used daily. Cover cuts, grazes, or broken skin with impervious dressings to avoid contamination. Workers should take a hot shower at the end of the working period or day. Emergency shower should be in close proximity to work area. Wear suitable protective, clothing.

Hygiene: When using sodium dichromate solutions, do not eat, drink, or smoke. Take off immediately all contaminated clothing.

FLAMMABILITY Product is not combustible.

44

--

FIRE-FIGHTING MEASURES: Incompatibility:

May react with readily oxidisable/combustible materials especially at elevated temperatures.

Decomposition:

Decomposition of Na2Cr207 (anhydrous salt) begins at 400°C liberating oxygen, no hazardous decomposition products observed under normal conditions of use.

Measures:

All extinguishertypes, such as water spray,foam,dry agent (carbondioxide, dry chemical powder), can be used to select on the basis of other materials present. Equipment Full protective clothing including self contained breathing apparatus STORAGE AND TRANSPORT

Store in a cool dry place out of direct sunlight. Store in well ventilated area. Store away from combustible, organic, or other readily oxidisable products. Keep containers closed when not in use. 45

---

-

--

- _.- - - - - - . -- . - - - -- .

SPILLS Isolate the spillage area. Increase ventilation. Wear protective equipment to prevent skin and eye contamination and inhalation of dust/mist. Collect and seal in properly labeled drums for disposal. If contamination of sewers or waterways has occurred, advise the local emergency services. FIREIEXPLOSION HAZARDS On burning will emit toxic fumes. Fire fighters to wear self-contained breathing apparatus if risk of exposure to dust/mist/vapor or products of combustion. ENVIRONMENTAL IMPACT Avoid contaminating waterways. Do not discharge into drainage, sewage, or water systems without pre treatment, and consultation & approval of waste disposal authorities. Hazard Category: Very Toxic

46

- --

PLANT LAYOUT

-- -

-

-

EFFlUEMENT

EXTENSION

TREATMENT

AREA

--

BOILER

[

HOUSE AND WATER

RAW

r-MATERIAL

'"

PLANT

AREA

STORAGE

I L___-

w

I

I

[:, --I,, II FINISHED

0 R K 5

WI

I

W

PRODUCT

n

.-

___

MAIN

EXIT

--..---.----

ROAD

,.----------

Fig. 2. PLANT LAYOUT

H 0 p

--..--.....-.-.

PLANT LAYOUT LAYOUT

The laying out of a plant is still an art rather than a science. In involves the placing equipment so that the following are minimized;

.

Damage to persons and property in case of a fire, explosion, or toxic release

.

Maintenance costs

.

The number of people required to operate plant

.

Other operating costs

. .

Construction costs The cost of the planned future revision or expansion

The first thing that should be done is to determine the direction of the prevailing wind. This can be done by consulting Weather Bureau records. Wind direction will determine the general location of many things. All equipment that may spill flammable materials should be located on the downwind side. Then if a spill occurs the prevailing winds are not apart to carry any vapors over the plant, where they could be ignited by an open flame, spark, or a hot surface.

48

Items that should be located Upwind of the plant Plant Offices

Electrical substation

Central Laboratories

Water treatment plant

Mechanical and other shops

Cooling tower

Office building

Air Compressors

Cafeteria

Parking lot

Store house

Main water pumps

Medical Building

Warehouses that contain non-

Change house

hazardous

Fire station

Non-explosive and

Boiler house

Non- flammable materials

Electrical Power house

Fired heaters All ignition sources

Items that should be located downwind of the plant Equipments that may spill inflammable materials Blown down tanks Burning Flares Settling ponds

For a similar reason the powerhouse, boilers, water pumping, and air supply facilities should be located 250 ft (75 m) from the rest of the plant, and on the upwind side. This is to minimize the possibility that these facilities will

49

be damaged in case of a major spill. This is especially important for the first two items, where there are usually open flames. Every precaution should be taken to prevent the disruption of utilities, since this could mean the failure of pumps, agitators, and instrumentation. For this reason, it may also be wise to separate the boilers and furnaces from the other utilities. Then, should fired equipment explode, the other utilities will not be damaged. Other facilities that are generally placed upwind of operating units are plant officers, mechanical shops, and central laboratories. All of these involve a number of people who need to be protected. Also, shops and laboratories frequently that are used primarily for quality control are sometimes located in the production area. Storage Facilities

Tank farms and warehouses that contain non-hazardous, nonflammable, and non explosive materials should be located upwind of the plant. Those that do not fit this category should not be located downwind of the plant, where they could be damaged and possibly destroyed by a major spill in the processing area. Nor should they be located upwind of the plant where, if they spilled some of their contents, the processing area might be damaged. They should be located at least 250 ft (75 m) to the side of any processing. Some authorities suggest this should be 500 ft. The same reasoning applies to hazardous shipping and receiving areas. Sometimes storage tanks are located on a hill, in order to allow the gravity feeding of tank cars. Care must be taken under these circumstances to see 50

that any slop over cannot flow into the processing, utilities, or service areas in case of a tank fir. When liquefied petroleum gases are used, the areas for containing spills are always below grade because the gases are denser than air. The gases will accumulate in the low areas will also not be asphyxiated.

Spacing of items

The OSHA has standard for hazardous materials that give the minimum distances between containers and the distances between these items and the property line, public roads, and building. These depend on the characteristics of the material, the type, and size if the container, whether the tank is above ground or buried, and what type of protection is provided. Specific details are provided for compressed gas equipment containing acetylene- air, hydrogen-oxygen, and nitrous oxide, as well as liquefied petroleum gases. They also prohibit the storage and location of vessels containing flammable and combustible materials inside buildings, unless special precautions are taken. Again, the major reason for including the layout in the preliminary plant design is so the transporting equipment and buildings may be sized, to make certain that no needed equipment is omitted and that the chosen plant site will be large enough. At this point, since most of the energy transfer equipment has not been sized, only its approximate location can be given.

51

Processing Area There are two ways of laying out a processing area. The grouped layout places all similar pieces of equipment adjacent. This provides for ease of operation and switching from one unit to another. For instance, if there are 10 batch reactors, these would all be placed in the same general area, and could be watched by minimum of operators; if they were spread out over a wide area, more operators might be needed. This type of scheme is best for large plants. The flow line layout uses the train or line system, which locates all the equipment in the order in which it occurs on the flow sheet. This minimizes the length of transfer lines and therefore reduces the energy needed to transport materials. In industries, it is used mainly for small volume products. Often, instead of using the grouped or flow line layout exclusively, a combination that best suites the specific situation is used.

Placing of Equipment Once a general scheme is decided upon, the processing area is divided into unit areas. The units should be grouped so that the number of operating personnel is minimized. The maximum loss concept must also be considered. Some companies place a limit in the maximum loss that can be expected if a fire or explosion occurs. This permits those watching the controllers to quickly investigate and determine the cause of any problems that might arise. It may be desirable to have two or more processes controlled from one location; this could reduce the number of operators required. In this case, the control room should be located in a relatively unexposed area near the edge of the processing area, but away from fired heaters. This is to protect both the employees and the equipment. 52

Elevation If there is no special reason for elevating equipment, it should be placed on the ground level. The superstructure to support an elevated piece of equipment is expensive. It can also be a hazard should there be an earthquake, fire, or explosion. Then it might collapse and destroy the equipment it is supporting as well as that nearby. Some pieces of equipment will be elevated to simplify the plant operations. An example of this is the gravity feed of reactors from elevated tanks. This eliminates the need for some materials- handling equipment. This is especially true first solids and slurry feed. Maintenance Maintenance costs are very large in the chemical industry. In some cases, the cost of maintenance exceeds the company's profit. The engineer must design to reduce these costs. The easiest way to reduce maintenance costs is to allow lots of extra space and to construct everything at ground level for easy access. However, this may increase construction and operating expenses and decrease the ease of operability. The engineer should determine what types of equipment need to be serviced by mobile cranes. These pieces of equipment will need to be located on the perimeters of the plant or on a road way. The roadways along which the crane will travel must have adequate over head and horizontal clearness. Adequate space must be left around all equipment so that it can be easily serviced and operated. For instance, a floating- head heat exchanger must have enough space so that the tube bundle can be removed from the shell and taken elsewhere for repairs. For tanks containing coils or "agitators,enough headroom must be provided so that these can be removed.

---

-------

Construction and Building Proper placing of equipment can result in large savings during the construction of the plant. For instance, large columns that are field- erected should be located at one end of the site so that they can be built, welded, and tested without interfering with the construction of the rest of the plant. Railroads, roadway and pipe racks

The main purpose of railroads is to provide an inexpensive means for obtaining raw materials and for shipping products. This means that they should be close to raw materials and or / product storage. Buildings and loading docks should be set back 8 ft (2.4 m) from the center of the railroad track. Spurs and switches should be laid out with a 100 ft (30 m) radius [3]. Roads are used not only for these purposes but to provide access for fire fighting equipment and other emergency vehicles, and for maintenance equipment. This means that there should be a road around the perimeter of the site. No roads should be dead- end. For safety's, there should be two ways to reach every location. All major traffic should be kept away from the processmg areas. Planning for Expansion and Improvements

Obviously, if the equipment has been over designed to meet the anticipated future expansion, no extra space needs to be provided. If, however, additional equipment will.be required, space should be allocated for it. The net result will be an increase in these initial costs of construction and some increase in material transfer costs, because the transfer lines will be longer. 54

-

- -

Building Including with the layout of the plant is the direction as to what types of buildings are to be constructed, and the size of each. When laying out buildings, a standard size bay (area in which there are no structural supports) is 20ft x 20 ft ( 6 m x 6 m). Under normal conditions, a 20- ft (6 m) span does not need any center supports. The extension of bay in one direction can be done inexpensively. This only increases the amount of steel in the long girders, and requires stronger supports. Lavatories, change rooms, lunch rooms, and medical facilities are all located inside buildings. The minimum size of the facilities is dictated by OSHA. It depends on the number of workers employed. Research laboratories and office buildings usually not included in the preliminary cost estimate. However, if they are contemplated, their location should be indicated on the pilot plan.

Processing Buildings Quality control laboratories are necessary part of any plant, and must be included in all cost estimates. Adequate space must be provided in them for performing all tests, and for cleaning and storing laboratory sampling and testing containers. Packaging equipment generally must be in enclosed buildings, and is often located at one end of the warehouse. If the material being packaged is hazardous, either this operation will be performed in a separate building, or a firewall will separate it from any processing or storage areas.

55

----

Warehouse

The engineer must decide whether warehouses should be at ground level or at dock level. The latter facilitates loading trains and trucks, but costs 15-20 percent more than one placed on the ground. It is usually difficult to justify the added expense of a dock- high warehouse.

56

ECONOMICS

ECONOMICS 1] Estimation of total capital investment: The total investment "I" involves A] The fixed investment in the process area, IF B] The investment in the auxiliary services, IA C] The investment in working capital, IW A] Fixed investment (IF): This is the investment in all processing equipment within the processing area. The approximate costs of various equipments used in the proposed sodium dichromate manufacturing are furnished below: S.No.

EQUIPMENT

NUMBER

COST (Rs. IN LAKHS)

1

Mill

1

5

2

Rotary Kiln

1

36

3

Crusher

1

22

4

Acidification Chamber

1

12

5

Rotary Filter

1

21

6

Leaching Tank

1

18

7

Evaporator

4

64

8

Crystallizer

1

36

9

Centrifuge

1

20

10

Dryer

1

19

11

Miscellaneous

80 TOTAL

333

.

COST ESTIMATION CALCULATION OF FIXED CAPITAL INVESTMENT (a) DIRECT COST FACTORS

S.No.

Item

% delivered Equipment Cost

1

Purchase equipment cost

100

2

Equipment Installation

15

3

Insulation

15

4

Instrumentation

15

5

Piping

75

6

Land and Building

30

7

Foundation

10

8

Electrical

15

9

Cleanup

5 280

Total Direct Cost Factor

Total Direct Cost = (Equipment Cost x Direct cost factor) / 100 = (333 x 280)/100 = 932.4 Lakhs

58

B] INDIRECT COST FACTOR:

S.No.

Item

% of the Direct Plant cost

1

Direct plant cost factors

100

2

Overall Contractor, etc.,

30

3

Engineering Fee

13

4

Contingency

13

Total

156

Indirect Cost = (Direct Cost x Indirect Cost Factor)/lOO = (932.4 x 56)/100 = 522.141akhs

Total Fixed investment in the plant

= Direct Plant

Cost + Indirect Plant Cost

= 932.4 + 522.14 = 1454.54 lakhs

2] AUXILLARY INVESTMENT (AI): Such items as steam generators, fuel stations, and fire production facilities are commonly stationed outside the process area and served the system under consideration.

59

- - -

CALCULATION OF THE INVESTMENT IN THE AUXILLARY SERVICES S.No.

% of Total Installed Cost

Item

100

1

Investment Total Fixed

2

Auxiliary Buildings

5

3

Water Supply

2

4

Electric Main Substation

1.5

5

Process Waste System

I

6

Raw Material Storage

1

7

Fire Protection

0.7

8

Roads

0.5

9

Sanitary and Waste Disposals

0.2

10

Communications

0.2

11

Yard and Fence Lighting

0.2

Total

112.3

Auxiliary Cost = (Total Fixed Investment x Auxiliary Cost Factor)/100 = (1454.54 x 12.3)/100 = 178.91 lakhs

Total Installed Cost = Total Fixed Investment + Auxiliary Cost

= 1454.54

+ 178.91

= 1633.441akhs

60

3] WORKING CAPITAL In this, the capital is fixed in the interest of the system in the form of ready cash to meet operating expenses, inventories of raw materials and products. The working capital may be conveniently assumed as 15% of total investment made in plant. Working Capital

= (1633.45

x 15)/85

= 288.25 lakhs

B] Estimation of manufacturing cost: The manufacturing cost that is the cost of the day today operation of the process can be divided into three items as follows: (A) Proportional to total investment: (B) Anticipated production rate (C) Labor requirement B.1] Estimation of cost proportional to investment: This includes the factor which is independent of the production rate and proportional to the fixed investment such as:

.

Maintenance - Labor and Materials

. . . . ·

Property taxes

Insurance Safety Expenses - Fire protection, Security and First Aid General Services, Laboratory, Roads, Etc., Administrative Services - Officers, Legal Charges, Etc., 61

--

--

.- - - -. _...-

- . - -- - -

+

....-

For this purpose, we shall charge 15% per year of total installed cost. Le., 1633.45 x 0.015 = 245.02 lakhs B.2] Estimation of Cost Proportional to Production Rate: The factors proportional rates are

.

Raw Materials Cost

. . .

Utilities Cost - Power, Fuel, Water steam, Etc., Maintenance Cost Chemical, Warehouse, Shipping Expenses

Assuming the cost proportional to production rate is nearly 60% of the total capital investment,

The Cost Proportional to production rate

= 1929.7 x 0.6 = 1153.02 lakhs

8.3] Estimation of Cost Proportional to labor:

The manufacturing cost proportional to labor might amount to 10% of total manufacturing cost.

Le., Cost Proportional to Labor = (245.02 + 1153.02) x 0.1

= 139.80Lakhs Total manufacturing cost = 245.02 + 1153.02 + 139.80

= 1537.841akhs

62

C] SALES PRICE FIXATION: The market price of sodium dichromate crystals = Rs. 59.5/Kg

D] PROFITIABILITY ANALYSIS: The total sales income = 59.5 x 3600000 = 2142 Lakhs/year D.1] Depreciation:

Using sinking fund method for calculating depreciation R= [(V - Vs) x 1]/[( 1 + i Y' n - 1 ] Where, R = Uniform annual payment at the end of each year V = Installed Cost of Plant Vs = Salvage Value of the plant after 'n' years n = Life Period (Assume to be 15 years) i = Annual Interest Rate (taken as 15%)

R- (1633.45 - 0) x {0.15/«1 + 0.15)"15 - 1 )} = 34.33 lakhs D.2] Gross Profit:

Gross profit = net income trom annual sales - annual manufacturing cost = 2142 - 1537.84 = 604.161akhs

63

D.3] Net Profit:

It is defined as the expected annual return on investment after deducting depreciation and taxes. The tax is assumed to be 40%.

Net Profit = Gross profit - Depreciation - (Gross profit x Tax Rate) = 604.16 - 34.33 - (604.16 x 0.4) = 328.17 lakhs

D.4] Annual Rate of Return:

Annual Percent return on the total initial investment

After income taxes = (100 x PII) = 100 x (328.17/1633.45) = 20.09 lakhs

D.5] Payout Period:

Payout Period = depreciable fixed investment/(profit per year + Depreciation! year) = 1633.45/ (328.17 + 34.33) = 4.51 years

64

CONCLUSION

--.

-- --.

---

----

.----

CONCLUSION This project gives a clear view of the manufacturing process of sodium dichromate from chromite ore. The chapters dealt with, provides a clear idea about the designing of the equipments, manufacturing costs of the plants, layout of the plant and safety measures to be taken while operating the plant. The cost .estimation shows that this project is considerably an economical one since the rate of return and pay back period are found to be in allowable range. Hence, this project should be feasible in a pilot scale and also be expanded to large scale

.. 65

--

--

BIBLIOGRAPHY 1. Chemical Engineers Handbook by Perry 2. Chemical Engineering, Volume: 6 by Coulson & Richardson 3. Unit Operation of Chemical Engineering by Warren L.Mc Cabe Julian C.Smith 4. Process Equipment Design by M.V.Joshi 5. Process Economics and Design by Peter & Timmerhauss 6. Encyclopedia of Chemical Engineering by Kirk & Othmer 7. Encyclopedia of Chemical Engineering by Mcketta 8. Ullman's Encyclopedia 9. Conceptual Design of Chemical Process by Douglas 10. Preliminary Chemical Engineering Plant Design by Nostrard & Reinhold 11. Preliminary Chemical Engineering Design by Baasel

12.ChemicalEngineeringGournal)May2001,August 2002

WEBSITES VISITED 1. www.lordschemical.com 2. www.dialindia.com 3. www.analytyka.com.mx

66