Lab 2 - Microsoft Visio

 

ENGINEERING GR PHICS

MICROSOFT VISIO 1

 

INTRODUCTION •

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The design of complex chemical plants requires the integration of very large amounts of diverse information. Process designers make use of standardized sets of graphical representations to assist in the development and transfer of these information sets. HOW to develop the information sets? 2

 

HOW? Break the process into its basic

complete complet e mass and

elements such as reaction and separation, and recycle sections 

energy balance and preliminary equipment preliminary specs

INPUT/ OUTPUT DIAGRAM

GENERIC DIAGRAM

a crude block flow diagram in which only feed and product streams are identified.

BFD

Include the material balance calculatio calculations ns

PFD

P&ID

includes the mechanical and instrumentation details 

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BLOCK FLOW DIAGRAM (BFD)

LEVELS OF DIAGRAM

Piping and Instrumentation Diagram (P&ID) often referred

PROCESS FLOW DIAGRAM (PFD)

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to as Mechanical Flow Diagram  

COMPARISON

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Block Flow Diagram Raw Materials

Products Process

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Group of connected blocks of process units Lines with arrows connect blocks and represent process streams Raw materials enter on the left Products exit on the right 4 kinds of “process” units:  units:  Mixers Reactors Splitters Separators

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 butter C12H22O11 flour eggs

Mixer

Raw chocolate chip Cookie dough

 NaCl  NaHCO3 Chocolate chips 

Raw chocolate chip Cookie dough

Reactor (Oven)

Baked chocolate chip Cookies

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3 dozen cookies 75% choc chip 25% peanut butter

4 dozen cookies 75% choc chip 25% peanut butter Splitter

1 dozen cookies 75% choc chip 25% peanut butter

4 dozen cookies 75% choc chip 25% peanut butter

3 dozen cookies 97.5% choc chip Separator

2.8% peanut butter

1 dozen cookies 8.3% choc chip 91.7% peanut butter

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BFD 9

 

Flowsheets The first step in any process design or analysis is the construction of a flowsheet that shows the major material flows and processing steps. steps. •

  common flowsheet symbols common abbreviations

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The flow sheet allows for better visualization visualization and quantification of the process.

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“A picture is worth a thousand words.”  

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A process flow sheet is comprised of units, represented represen ted by simple shapes like circles or

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rectangles.

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Some common flowsheet symbols

Pumps are used to increase a fluids pressure so the fluid will flow from high pressure to low pressure, pressure, or u used sed to condense a fluid or increase the speed of of a chemical reaction. Gas compressor – a different different unit description is used as the fluid responds differently differ ently than liquid in a pump (ie increase in pressure causes gas to condense)

11 Gas expander or turbine is similar but with flows reversed. Valves are needed to control flows between various units.

 

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Combiner and splitter:

Avoid ccrossing rossing stream streams. s. If streams must ccross, ross, you need to indicate whether they mix or not.

Ambiguous

streams combine and split

streams cross without mixing

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Example

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tabulate process design values for the components in different operating modes, typical minimum, normal and maximum.

PFD 14

 

PFD Should NOT include: pipe classes

pipe line numbers

minor bypass lines

isolation and shutoff valves

maintenance vents and drains

relief and safety valves

code class information

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SYMBOLS FOR DRAWING PFD

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PFD

 

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P&ID •

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A family of functional one-line diagrams showing hull, mechanical and electrical (HM&E) systems like like piping, and cable block diagrams diagrams.. Show the interconnection of process equipment and the instrumentation instrumentation used to control the process. They are the primary schematic drawings used for laying out a process control installation in a factory or plant. A standard set of symbols may be used to prepare drawings of processes, for instance the instrument symbols used may be based on Instrument Society of America (ISA) Standard S5.1.

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 A P&ID should not include : Instrument root valves

equipment rating or capacity

control relays

manual switches

primary instrument

pressure temperature and

tubing and valves

flow data

elbow, tees and

extensive

similar standard fittings

explanatory notes

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P&ID •

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The P&ID mixes pneumatic / hydraulic elements, electrical elements and instruments on the same diagram It uses a set of symbols defined in the ISA S5.1 standard. Examples of pneumatic / hydraulic symbols: pipe 350 kW 

heater

valve one-way valve (diode)

vessel / reactor

binary (or solenoid) valve (on/off) analog valve (continuous) heat exchanger pump, also

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P&ID

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P&ID  

INSTRUMENTATION IDENTIFICATION The first letter defines the measured or initiating variables such as Analysis (A), Flow (F), Temperature (T), etc. with succeeding letters defining readout, passive, or output functions such as Indicator (I), Record (R), Transmit (T), and so forth. *(C for control)

FIC  V1528 

tag name of the corresponding variable

mover (here: solenoid) S 

function

(here: valve)

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INTRODUCTION TO VISIO

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26 10/16/2014

 

General Equipment & Details

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 Vessel, Pump & Others

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EXERCISE 1 : PFD 29

 

Draw a PFD from the following simplified description of the synthesis of ammonia: A mixture of hydrogen and nitrogen is fed to a catalytic reactor where some of the hydrogen and nitrogen is converted to ammonia. The reactor effluent is sent to a condenser where all of the ammonia is condensed. The condensed ammonia is sent to product storage. The uncondensed hydrogen and nitrogen are recycled by being mixed with a fresh feed of the same composition. The resulting mixture is fed to the reactor. 30

 

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Type of process? •

Reactor and condenser are continuous

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Storage tank is semi-continuous

Reaction: N2  + 3H2 

2NH3

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A mixture of hydrogen and nitrogen is fed to a catalytic reactor where some of the hydrogen and nitrogen is converted to ammonia. The reactor effluent is sent to a condenser where all of the ammonia is condensed. The condensed ammonia is sent to product storage. The uncondensed hydrogen hydrogen and nitrogen are recycled by being

mixed with a fresh feed of the same composition. The resulting mixture is fed to the reactor. •Step

1 is the feed to the reactor:

“feed” 

N2 H2

reactor

“effluent”

NH3 N2 H2 

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A mixture of hydr hydrogen ogen and nitrogen is fed to a catalytic reactor where some of the hydrogen and nitrogen is converted to effluentt is sent to a condenser where all ammonia. The reactor effluen of the ammonia is condensed. The condensed ammonia is sent to product storage. The uncondensed hydr hydrogen ogen and nitrogen are recycled by being mixed with a fresh feed of the same

composition. The resulting mixture is fed to the reactor reactor.. •Step

2 is to purify the product:

“feed” 

N2 H2

condenser

reactor

“effluent”

NH3 N2 H2 

NH3 liquid

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A mixture of hydrogen and nitrogen is fed to a catalytic reactor where some of the hydrogen and nitrogen is converted to ammonia. The reactor effluent is sent to a condenser where all of the ammonia is condensed. The condensed ammonia is sent to product storage.  The uncondensed hydrogen and nitrogen are recycled by being mixed with a fresh feed of the same composition. The resulting mixture is fed to the reactor. •Step

3 is to send product to storage:

“feed” 

N2 H2

condenser

reactor

“effluent”

NH3 N2 H2 

NH3 liquid Storage

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tank  

A mixture of hydrog hydrogen en and ni nitrogen trogen is fed to a catalytic reactor where some of the hydrogen and nitrogen is converted to ammonia. The reactor effluent is sent to a condenser where all of ammonia is condensed. The condensed ammonia is sent to the product storage. The uncondensed hydrogen and nitrogen are recycled by being mixed with a fresh feed of the same composition. The resulting mixture is fed to the reactor.  purge

•Step 4 is to recycle unreacted feeds: recycle

 N2, H2 “feed”   “feed”  N2 H2

condenser

reactor

“effluent”  NH3  N2 H2 

 NH3 liquid Storage

tank

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EXERCISE 2: CREATING A P&ID 37

 

Instrumentation and Control •

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Instruments are used to sense process variables and drive control valves. These are denoted on P&IDs by circles with letters: LC

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FRC

Valves are connected by solid lines to the point where variables are measured, and by dotted lines to the equipment they control

FRC

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Instrumentation symbols  As 1st letter  A

analyzer

C F

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As 2nd letter

As 3rd  letter

Alarm

Alarm

controller

controller

flow

I

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indicator

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level

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L

Level/liquid

P

Pressure

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R

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Recorder

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T

Temperature emperatu re

V

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Valve

D

Differential

Differential

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r

ratio

ratio

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First letter describes the variable sensed by the instrument: Pressure (P), Temperature Temperature (T), Flow (F), level or liquid level (L or LL), composition (A) The second and third letters describe describ e the action taken: Record ( R), Indicate (I), Sound an alarm (A), or Control (C )

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Explain the symbols: LC

FRC

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Main pieces of equipment are the column (C1), accumulator drum (D1), reboiler (E2) and condenser (E1). The distillation column (C1) separates the feed stream according to volatility into overhead and bottoms  products. The heat exchangers (E1) and (E2) condense the overhead vapours and partially vaporize the liquid from the bottom of the column. The drum (D1) accumulates the condensed liquid liq uid and also accommodates surges in overhead product rate.

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Control elements are shown by circles and dashed lines.

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Description  

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The rate of bottoms bottoms withdrawal is controlled by the liquid level in the  bottom of the column. When the level rises the valve is opened to increase the withdrawal rate and thus lower the level. The net bottoms flow is controlled by an analyzer (with recorder) which sets the flow controller on the steam to the reboiler to maintain the bottoms composition within specified limits. The net overhead is withdrawn from the drum on level control (ie when the level in D1 rises the valve is opened). This keeps the level in the tank within a preset upper and lower limits. The rate at which reflux is returned to the column is controlled by the Temperature at a particular point in the column, when this thi s temperature rises the valve is opened and more reflux flows to the column. This instrument is an indicator as well as a controller so it sends a signal proportional to the temperature to a readout instrument in the control room. The column is feed controlled by an FRC.

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