summertraining report

7/30/2019 SummerTraining Report

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Heat & Mass Balance Across Booster and

Hyper Compressors in an LDPE plant

Department of Chemical Engineering

Indian Institute of Technology, Guwahati

Roll No. : 09010738


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ACKNOWLEDGEMENT

I would like to sincerely thank the Organization,for giving me the opportunity

of this industrial training at their Manufacturing Division.


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TABLE OF CONTENTS

1. AIM........................................................................................................................................................... 1

2.INTRODUCTION ........................................................................................................................................ 2

i.LDPE Plant .............................................................................................................................................. 2

ii.Applications of LDPE.............................................................................................................................. 2

iii.Grades of LDPE Generated ................................................................................................................... 3

iv.Grade Nomenclature ............................................................................................................................ 3

v.Sections of LDPE .................................................................................................................................... 4

vi.Polymerization...................................................................................................................................... 4

vii.Specifics of the Polymerization Process in the Plant ........................................................................... 5

viii.Process Summarized Description .................................................................................................... 6

3.DETAILED DESCRIPTIONS .......................................................................................................................... 8

i.Ethylene Storage Vessels: V01, V02, V03 ............................................................................................... 8

ii.Tail Gas Compressor (K01) .................................................................................................................... 9

ii.Combined Compressor (K02) ................................................................................................................ 9

iii.Hyper Compressor (K03) .................................................................................................................... 10

iv.Final Stage Coolers ............................................................................................................................. 11

v.Reactor ................................................................................................................................................ 12

vi.MP/ LP Separator/Extrusion Hopper (V12/V14/V15) ........................................................................ 15

vii.Extruder ............................................................................................................................................. 16

4.CALCULATIONS ....................................................................................................................................... 17

i.PART- 1 ................................................................................................................................................. 19

a.Sample Calculations: .................................................................................................................. 20

b.Result ......................................................................................................................................... 23

ii.PART 2 .............................................................................................................................................. 24

a.Sample Calculations: .................................................................................................................. 25


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b.Result ......................................................................................................................................... 28

LISTOFFIGURES

FIGURE 1:POLYMERIZATION REACTION .................................................................................................... 2

FIGURE 2:ETHYLENE STORAGE VESSELS AND COMBINED COMPRESSOR ........................................................... 8

FIGURE 3:HYPER COMPRESSOR ............................................................................................................ 10

FIGURE 4:FINAL STAGE COOLERS.......................................................................................................... 11

FIGURE 5:REACTOR ........................................................................................................................... 12

FIGURE 6:GAS SEPARATORS AND EXTRUDER ........................................................................................... 15

LIST OF TABLES

TABLE 1:READINGS OF COMBINED COMPRESSOR ..................................................................................... 19

TABLE 2:READINGS OF HYPER COMPRESSOR ........................................................................................... 19

TABLE 3:COMBINED COMPRESSOR MOLLIERE CHART VALUES..................................................................... 22

TABLE 4:HYPER COMPRESSOR MOLLIERE CHART VALUES........................................................................... 22TABLE 5:RESULTS OF EFFICIENCY CALCULATIONS ...................................................................................... 23

TABLE 6:TEMPERATURE READINGS FOR K02 COOLERS .............................................................................. 24

TABLE 7:TEMPERATURE READINGS FOR K03 INTERSTAGE COOLERS.............................................................. 24

TABLE 8:TEMPERATURE READINGS FOR FINAL STAGE COOLERS .................................................................... 25

TABLE 9:HEAT LOAD CALCULATIONS FOR K02 COOLERS ............................................................................ 26

TABLE 10:HEAT LOAD CALCULATIONS FOR K03 INTERSTAGE COOLERS.......................................................... 27

TABLE 11:HEAT LOAD CALCULATIONS FOR FINAL STAGE COOLERS ................................................................ 28


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AIM

The Aim of this project was to study the workings of the LDPE plant, focusing on the Booster

(K02) and Hyper (K03) compressors in the process, and mass/energy calculations across these

two units of equipment. This project had three objectives.

1. Mass and Energy balance calculations across the K02 and K03 compressors.2. Efficiency calculations for the K02 and K03 compressors.3. The calculation of heat load across the inter stage and final coolers for both K02 and K03

compressors.


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INTRODUCTION

LDPE Plant

The LDPE production plant at -- is designed for producing 1,10,000 tons per annum of low

density polyethylene and it is built under license from -- . This plant is responsible for a daily

production of around 13 tons per hour of low density polyethylene. Low density polyethylene is

a polymer generated from the monomer of ethylene, subject to specified settings of

temperature, pressure etc. to enhance the branching in the polymer generated and produce

specifically 3 different grades of low density polyethylene as the end product from this plant.

Figure 1: Polymerization Reaction

Applications of LDPE

The applications of the pellets produced in this plant are not the final product as sold in the

market; they are further to be manufactured to produce various applications of food packaging

and plastic bags. The secondary products fashioned from LDPE include:

1. Heavy duty bags2. Carrier bags3. Milk sachets4. Juice and milk cartons is made of liquid packaging board, a laminate ofpaperboard and

LDPE (as the water-proof inner and outer layer), and often with of a layer of aluminum

foil
http://en.wikipedia.org/wiki/Carton#Aseptic_cartonhttp://en.wikipedia.org/wiki/Liquid_packaging_boardhttp://en.wikipedia.org/wiki/Paperboardhttp://en.wikipedia.org/wiki/Aluminum_foilhttp://en.wikipedia.org/wiki/Aluminum_foilhttp://en.wikipedia.org/wiki/Aluminum_foilhttp://en.wikipedia.org/wiki/Aluminum_foilhttp://en.wikipedia.org/wiki/Paperboardhttp://en.wikipedia.org/wiki/Liquid_packaging_boardhttp://en.wikipedia.org/wiki/Carton#Aseptic_carton


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5. Shrink film for wrapping6. Covers for outdoor storage of grains or silage7. Food and pharmaceutical packagingGrades of LDPE Generated

The different grades produced by this plant vary in mainly 3 different polymer properties with

each other, namely: Melt flow Index, Density and the Molecular weight distribution. The melt

flow index can be described as the number of grams of the polymer resin which can be forced

through 2.095 mm orifice when subjected to a 2.16 kg load in 10 minutes at a temperature of

190 degrees Celsius. Density is the ratio of mass per occupied volume and the molecular weight

distribution gives the general picture of the degree to which polymerization has taken place to

produce long chains. Based on the density criteria, the value for LDPE ranges from 0.916 to .930

g/cc; other types of polyethylene exhibit higher than 0.930gm/cc densities.

Grade Nomenclature

The different grades produced are denoted separately with separate codes. This code or name

comprises of an eight numbered alphanumeric name.

According to naming convention as briefed above, the LDPE plant produces 3 variants:

1005FY20, 1070LA17 and 1020FA20. It should be noted that this plant generates one grade of

polymer one at a time and not simultaneously. The grade to be produced is decided based on

1 070 L A 17

Complex

NumberMelt Flow Index

070: 0.70 g/10 min

Application

F: Film

L: Lamination

Additive System:

A: No additive

Y: Slip

2nd

and 3rd

decimals of

Density (0.917)


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the market demand, and generally in one month of production, around 3 grade changes occur.

Changes in grade, signify different running conditions required in sections of the plant such as

maintained temperature and pressure levels, although the basic feed of ethylene remains the

same. It should be noted that two of these are of the film grade; they are cheaper to produce

and sold at a lesser price in the market. Subsequently, the other one is of the lamination grade

that is likewise costlier to produce and in return fetches a higher price in the market.

S.No. Grade MFI

1. 1005FY20 (Film grade) 0.5g/10min

2. 1070LA17 (Lamination grade) 7.0g/10min

3. 1020FA20 (Film grade) 2.0g/10min

Sections of LDPE

For understanding the running of the plant, its separate sections can be understood to give a

clearer picture of how it functions. Generally, LDPE plant covers 7 sections with each having its

own duty and function. The Utilities section takes care of monitoring all the utilities required in

running the plant, and is in charge of the Catalyst preparation also. Under the polymerization

section come the reactor, the catalyst injection, and the gas and wax separators. In the

Extrusion section, the activities of the extruder, and the drying and conveying of pellets to the

silos is monitored. The Compressor section houses the different ethylene vessels and

compressors (tail gas, booster, primary and hyper), that are responsible for the compression of

the gas before entering the reactor. The Bunker section houses and stores the catalysts CA, C1,

C2 and C5 and the Bagging section is responsible for packaging the pellets into the final packed

products.

Polymerization

Polymerization of ethylene into LDPE is a highly pressured addition polymerization reaction.

Firstly, it should be known that addition polymerization takes place in three steps, namely:


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initiation, propagation and termination. In the first step, external catalysts are used, that

decompose into initiators that react with inactive monomer molecules to transfer the activated

site onto them. This activated site could either be a free radical, a cation or an anion. In our

case, free radical initiation is followed. In the propagation step, this activated molecule keeps

adding monomers, and other molecules found in the immediate vicinity and causes in the

growth of the resulting polymer chain. Lastly, this process ends with the termination step that

occurs when the active site in the macromolecule chain is destroyed and suspends it from

further reaction or chain growth.

Specifics of the Polymerization Process in the Plant

The above stated polymerization reaction takes place in an autoclave reactor in this plant. It is

designed to specifically withstand very high pressures and moderately high temperatures, and

is divided into 5 separate but interconnected chambers called zones, through which five

separate points of input of initial feed is possible. Most of the volume inside this autoclave

reactor is taken up by the powered stirrer, which ensures optimal mixing in the reactor within

each zone to resemble a continuously stirred mixed flow reactor to a certain degree. With all

the specifications of temperature and pressure in consideration, the conversion into polymer

comes to a value of around 18% in this reactor. In addition, the catalyst initiators that are

necessary as mentioned above come in 4 different chemical species:

S.No. Name Species

1. CA Di-tertiary-butyl peroxide

2. C1 tertiary-butyl-peroxybenzoate

3. C2 tertiary-butyl-peroxy-2-ethylhexanoate

4. C5 tert-butyl peroxypivalate

Different combinations of these in specific concentrations as per the design conditions are

injected at the 5 separate entry points to the reactor in pressurized conditions.


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Process Summarized Description

Fresh ethylene makes its way into our plant from GC and is fed to the V03 ethylene vessel at

around 70 bars. The flow rate of ethylene may vary a little from one day of production to

another but is tried to be maintained at a range kept around 12-13 tons per hour. This fresh

flow rate joins the recycled ethylene, flowing at a rate of 7-8 tons per hour and together enters

the primary compressor at a flow rate of 20tonnes per hour. Across the primary compressor the

gas is compressed and the pressure of flow is increased to 250 bars in two stages. After the gas

exits the primary compressor, it is joined by the recycle gas that comes from the medium

pressure separator at the same pressure of 250 bars. The flow of this combined stream

becomes 70 tons per hour and goes into the hyper compressor after being divided into 4

streams to be fed into the 4 separate cylinders in the first stage of the hyper compressor. In the

hyper compressor the ethylene gas is compressed to the final pressure of 1300-1500 bars

(specific for each grade) in two stages. After exiting each stage the flow streams go through

coolers to bring down the increased temperature of the gas to enable the compressing in the

next stage, or to maintain the temperatures of streams before reaching the reactor vessel.

After the streams of gas have exited the second stage of the hyper compressor, they are

separated into 5 streams, and each of these streams goes through a train of heat exchangers.

These five streams are cooled to specific temperatures and enter the reaction vessel at 5

strategic points in the reactor vessel, characterized by each zone. Along with the ethylene gas

feed, at the input point, each stream is injected with pressurized catalyst specific for that

stream. After the polymerization process that takes place in the reactor, the exit stream enters

the medium pressure separator (V12). At this point, the temperature of the feed is

approximately around 270-280 degrees Celsius and at a pressure of 250 bars. There is a

letdown valve at the bottom of the reactor vessel, and across it flashing of the stream occurs.

Due to this flashing, the expanded, unreacted gas escapes the polymer mass and escapes

through the top of the separator vessel and is led through various exchangers and filters to

filter out residual wax and then fed to the mainstream at the suction side of the hyper

compressor. The polymer at the bottom of V12 is exited through and flashed across to the low

pressure separator (V14) at a pressure of 15 bars. Again, the left over unreacted gas in the


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polymer mass expands, and escapes through the top to be recycled and fed into the

mainstream process into the V02 ethylene gas holding vessel. From the V02 holding vessel it is

fed into the Booster compressor to raise the pressure of the recycled stream to 68-70 bars. The

polymer that exits the low pressure separator is then again flashed to the next vessel called the

extrusion hopper. Gas separation from the polymer mass takes place in this also and the

recycled gas is returned back to the starting of this process, it is called tail gas. It is taken to V01

(pressure: 0.4-0.5), and from there compressed in the tail gas compressor to 15 bars. This

further joins the recycle gas from the low pressure gas separator and with it enters into the

booster compressor. The polymer that is left at the bottom of the extrusion hopper is directly

fed into the extruder, and turned into consistent melt as it is screwed through the body of the

extruder. It is pushed through the die into a water tank and cut into small pellets by the

rotating cutter. The fluidized pellets are transported to the dryer with the help of an external

motor P15, and the cyclone separator setup in the dryer, dries the excess water off the pellets

and them into the conveying section of the plant. Here, the pellets through a number of dusters

etc. are transported to the silos for storage. There are three types of silos. The control silos, the

storage silos and the off grade silos. Pellets are routinely kept in a control silo for an hours

time, so that a sample of it can be taken to the lab, and tested for the required quality. From

the control silos it is then transported to the other storage silos. From these silos, it is driven to

the bagging section of the plant, where the pellets are packed in measured sacks of 25 kgs as

the finished product, and transferred to the logistics department of the site.


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DETAILED DESCRIPTIONS

Ethylene Storage Vessels: V01, V02, V03

As can be seen clearly below in the diagram, these vessels hold the ethylene that comes fresh

from the GC plant along with the recycled ethylene gas that remains unreacted at the end of

the process.

V01: It holds the largest volume and holds the least pressured gas i.e. the recycled gas

separated from the extrusion hopper (V15). The discharge from this vessel is fed to the suction

side of the tail gas compressor (K01).

V02: It takes the gas from the discharge of K01 and takes in the recycled gas from the LP

separator (V14) in its volume. The discharge from this vessel is fed to the suction side of the

Booster compressor.

V03: It holds the least capacity and most flow rate hence in effect explaining the high pressure

withstood. The discharge from the booster compressor and the fresh ethylene from GC plant is

held in it and fed to the primary compressor.

Figure 2: Ethylene storage vessels and Combined Compressor


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Tail Gas Compressor (K01)

The recycled gas collected in V01 is compressed from 0.5 bars to 15 bars in 3 stages. It is a

reciprocating compressor with 3 stages of 0.5 to 2.8 bars, 2.8 to 7.5 bars and lastly from 7.5 to

15 bars. Practically, as a gas is compressed, the temperature increases, and hence limits the gas

compressibility with increased temperature. In order to optimize the compression work, the gas

is cooled before it goes to the next stage in the compressor. For this purpose inter-stage coolers

are used. After stages one and two in K01, shell and tube type exchangers E02 and E03 are

used. After the gas exits K01, a final stage cooler (STHE) of E04 is used.

Combined Compressor (K02)

The combined compressor combines the booster compressor and the primary compressor

together by both being driven by the same motor MK 02. They are both reciprocating

compressors. The booster compressor compresses the feed from the V02 vessel. It incorporates

two stages of 15 to 30, and from 30 to 70 bars. Inter-stage cooler used is E08 (STHE) and final

stage cooler of E09 (STHE). From discharge of E09, it makes its way to V03 to join the fresh

ethylene input.

The primary compressor working on the same shaft of the MK02 motor compresses the gas

from 70 to 250 bars in two stages: 70-95 and 95-250, using the reciprocating compressing

mechanism. The inter- and final stage coolers used for this compressor include the shell and

tube type exchangers E12, E13 and E14.


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Hyper Compressor (K03)

Figure 3: Hyper Compressor

The hyper-compressor performs its compression of 250 to 1500 bars in two stages. Each stage

comprises of 4 cylinders, through which where the gas stream is divided equally. In all, the

hyper compressor consists of 8 cylinder pistons attached to one shaft which is powered by one

motor, namely MK 03. Stage one compress the gas stream from 250 to 940-50 bars. The

discharge from each cylinder of Stage one is divided into three streams by a bifurcation block

(W06/1/2/3/4) and each of these divided streams goes through 2 double pipe heat exchangers

(one from the E15 series and one from the E16 series) for the inter stage cooling. Hence, the

four cylinders of stage one, give rise to 12 individual streams, and there are 12 heat exchangers

in each of the E15 and the E16 series, 24 in total. The 12 streams come together to make 4

streams again and enter the Stage two where compression from 940-950 to 1500 bars.


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Final Stage Coolers

Figure 4: Final Stage Coolers

The four discharge streams from the Stage two of K03, come together in the bifurcation

block of W08 and are then divided into six streams. These consist of the five streams that lead

to the final stage coolers and one recycle stream. Normally, under running condition the recycle

stream doesnt hold any substantial gas flow, so it can be ignored for mass balance calculations.

Each of the five streams branching from W08 is to enter the reactor at different points in

different zones; hence they all need to be cooled to different temperatures that are specified

by the design calculations. Except for the stream that enters the reactor from the top, for stirrer

motor cooling, all other streams again are cooled using a series arrangement of two double

pipe heat exchangers one from each the E18 and E19 series. Depending on the grade of the

polymer that is being produced, the temperature of these various streams is adjusted by using


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chilled water (WCH)/DM-water (WDM) or hot water (WH) in DPHEs. If WCH is being used, the

exchangers are said to be functioning in the cooling mode and if WH is being used, the

exchangers are said to be in the heating mode.

Reactor

Figure 5: Reactor

It is an autoclave type reactor which consists of a normal vessel which is divided into 5 separate

zones. The reactor also consists of a motorized stirrer, which supports optimizing the

conversion obtained from the quasi-continuously stirred mixed flow type reactor that it is. The

feed includes streams of ethylene that are injected with catalysts and are inputted to the

reactor in the first four zones from top; the last zone at the bottom is not fed with any

ethylene; however, catalyst alone is injected into it. Also, the hottest stream from the final

stage coolers is not injected with any catalyst and is fed from the very top of the reactor vessel

to cool the stirrer motor mounted at the top of the stirrer. Each zone is fed gas streams

maintained at different specific temperatures and injected with different cocktails of the

catalysts, each specified in the design instructions of the plant. These specifications cater to the


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need to produce low density polyethylene with the precise properties of the polymer required

to be manufactured.

Specifics that should be noted about the reactor: The reactor maintains its operation in spite of

the immense pressure of around 1300-1500 bars (depending from grade to grade) it withstands

due to the pressurized feed inputs. Due to the exothermic nature of the polymerization

reaction, the temperatures in each zone escalate also ranging from 180 to 285 degrees Celsius.

In such extreme conditions of pressure and temperature involving hydrocarbon gases, there is

constant threat of the process disintegrating to uncontrollable run away reactions such as:

These reactions are explosive in nature and can lead to tremendously dangerous situations like

bursting of the reactor vessel; consequently, many safety systems are in place to avoid this, or

worst case scenario, relieve the pressure using the pyrotechnic safety system if such a reactiondoes take place.

The letdown valve: One of the main features of the reactor is the letdown valve that is placed at

the bottom of the reactor. Through this valve the polymer slurry discharges out and enters the

MP separator. It is of importance to note that this is responsible for controlling all the pressures

of the gas streams leading from the final discharge of the hyper compressor. After the

discharge, other than the letdown valve, only 5 UDHE isolation valves are present after exiting

the final stage coolers. The purpose of the UDHE valves is to stop the ethylene feed from

reaching the reactor in the case of tripping of the plant. They dont contribute to the controlling

the streams in running condition; this being left to the sole letdown valve in the reactor

bottom. Also, across the letdown valve, the flashing of the product slurry in the medium

pressure separator occurs.


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The pyrotechnic safety system: This safety system reacts when the pressure inside the reactor

has exceeded well above a safe limit. It relieves the vessel of all its contents by expelling them

through the stacks that are connected to the body of the reactor. The stacks contain Rupture

Discs (RDs) that otherwise block the entry of the contents in the reactor to the stacks. However,

in high pressure conditions, these discs are the first to burst, and provide an alternative exit to

the explosive nature of the contents of the reactor. Hence it prevents hazards from bursting of

the reactor vessel in an uncontrolled manner.

The stacks are maintained under 10-mbar nitrogen pressure and balloons are placed in each

stack to hold the pressure. A water tank is placed between these two stacks (externally). It is

also maintained under nitrogen pressure. The outlets of this tank are discharged through a

nozzle, which is used for spraying water inside the stacks. When the RD bursts (at 1700 bar) due

to excess pressure inside the reactor, the water from the tank is ejected outwards towards the

nozzles inside the reactor. Due to this action the high pressure ethylene gas ejected out of the

stacks gets cooled down and reduces the likelihood of fires/flares due to minor sparks, once

discharged into the atmosphere. This way, not only does the gas gets cooled, but it also gets

diluted with the steam generated due to contact of water with the high temperature gas.


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MP/ LP Separator/Extrusion Hopper (V12/V14/V15)

Figure 6: Gas separators and Extruder

The conversion obtained in the reactor is just around 20%, so a large amount of the discharge

from the reactor still includes unreacted ethylene gas that must be separated and recycled

back. The molten waxy product LDPE from the reactor plus the unreacted gas comes to the MP

separator V 12 which is operating under 250 bars of pressure. This vessel is also provided with

the pyrotechnic safety system as described in the previous section. The product drains out from

the bottom of the tank whereas the unreacted gas flows out from the top of the vessel. The

product still contains some unreacted gas that is recovered in the LP separator V 14. The last

traces of the gas are recovered as Tail Gas in the extrusion hopper V 15. The product goes to

the extruder from where the pellets are pneumatically conveyed to drying section and then to

the storage silos.

In each of these three separation vessels a technique of radioactive decay of Cesium- 137 is

used to measure the height of polymer level at the bottom of the vessel.


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Extruder

Basically extrusion is the process by which a material is forced to flow in continuous manner

due to the motion of an internal screw through the length of the vessel. It is then forced into a

forming die shaped particularly for the polymer melt to be finally cast into. Hence in this piece

of equipment, the LDPE polymer separated from ethylene gas (by 3 gas separators) is softened

by heat and injected with additives to a melt of uniform consistency. This melt is then drawn

through a die and immediately cut as it passes through the die into a water tank. The purpose

of the tank is to cool the melt and cast it into the pellet form by hardening due to temperature

drop in the water. These pellets are carried out so that it can be readily conveyed and formed

without destroying the desirable final properties of the material to the bagging section where

the final packaging details of the product are carried out.


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CALCULATIONS

The first objective was to study the compression process that was taking place in the K02 and

the K03 compressors.

The compressors are of the reciprocating type.

Assumption: In the reciprocating compressor, the compression process that is followed is a

POLYTROPIC PROCESS, which means the gas in the compressor would follow the following

equation in the compressor:

Assumption: Equation of state of the gas in such extreme temperatures and pressures willsurely deviate from the ideal gas law; hence compressibility factor must be accounted for:

To find the polytropic coefficient (n), however the compressibility factor is not considered:

( )

(

) (

)

()


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The work done by polytropic compression:

( )

The real work done observed:

Hence the value of efficiency, , is given by:

For the next objective, the heat load calculations were done based on the amount of heat

gained/ lost from the main stream of ethylene across the inter-stage and final coolers that

were used.


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PART- 1

Efficiency Calculations

Readings taken:

Combined Compressor

K02 Pressure(bars) Temperature(C)

Suction Discharge Suction Discharge

BOOSTER

stage I 14.51 30.4 30.4 89.7

stage II 30.4 64.7 35.4 92.8

PRIMARY

stage I 61.3 94.7 24.1 56.3

stage II 94.7 259.2 35.7 83.4

Table 1: Readings of Combined Compressor

Hyper Compressor

K03 Pressure(bars) Temperature(C)

Suction Discharge Suction Discharge

STAGE1

1A1 249 955 31.7 81.2

1B1 249 955 31.7 80.8

1A2 247 960 31.5 81.2

1B2 247 960 31.5 81.2

STAGE2

2A1 932 1552 35.2 59.2

2B1 956 1552 38.5 63.1

2A2 936 1552 35 54

2B2 933 1552 35.4 54.8

Table 2: Readings of Hyper compressor


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Sample Calculations:

Taking the readings for cylinder 1A1, in the first stage of K03

Step one, value of Z needed for both suction and discharge side

To find value of Z,

Corresponding to values of P and T, readings for specific Volume (V) and Enthalpy (H) are taken

from the Mollier Chart of Ethylene.

()

Step two, after value of Z has been found, the values of n are found:

Step three, to calculate the polytropic work:

()


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From the values of Hsuction and Hdischarge taken from the Mollier chart, Wobs can be found:

Efficiency then is got by,


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Values read from the Mollier chart:

K02Pressure

(kg/cm)

Temperature

(C)

Specific Volume

(m/kg)

Enthalpy

(kcal/kg)

Psuc Pdis Tsuc Tdis Vsuc Vdis Hsuc Hdis

Combined

Compressor

BOOSTER 15.820 32.028 30.4 89.7 0.056 0.031 159 182

32.028 67.014 35.4 92.8 0.024 0.013 154 170

PRIMARY 63.546 97.614 24.1 56.3 0.0065 0.005 120 126

97.614 265.40 35.7 83.4 0.0035 0.003 104 124

Table 3: Combined Compressor Mollier chart values

K03

Pressure

(kg/cm)

Temperature

(C)

Specific Volume

(m/kg)

Enthalpy

(kcal/kg)

Psuc Pdis Tsuc Tdis Vsuc Vdis Hsuc Hdis

HyperCompressor

STAGEI

255 975.12 31.7 81.2 0.00245 0.00208 87 129

255 975.12 31.7 80.8 0.00245 0.00208 87 129

252.96 980.22 31.5 81.2 0.00245 0.00204 87 130

252.96 980.22 31.5 81.2 0.00245 0.00204 87 130

STAGEII

951.66 1584.06 35.2 59.2 0.00195 0.00186 102 134

976.14 1584.06 38.5 63.1 0.00194 0.001865 104 135

955.74 1584.06 35 54 0.00195 0.00185 102 130

952.68 1584.06 35.4 54.8 0.00195 0.00185 102 131

Table 4: Hyper Compressor Mollier chart values


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Using these values of V and H, continuing with the calculations leading to final results:

Pressure(bars) Temperature(C) Work(J/mol) Efficien

P1 P2 T1 T2 Z1 n Wobs Wpoly

Combined

Compressor 16 31 30.4 89.7 0.9641 1.339 2694 1878 69.70

31 66 35.4 92.8 0.8230 1.301 1874 1699 90.63

62 96 24.1 56.3 0.4590 1.315 703 513 72.93

96 260 35.7 83.4 0.3654 1.168 2343 1009 43.06

Hype

r

Compre

ssor

250 956 31.7 81.2 0.6770 1.126 4920 2482 50.45

250 956 31.7 80.8 0.6770 1.125 4920 2481 50.42

248 961 31.5 81.2 0.6720 1.126 5038 2488 49.39

248 961 31.5 81.2 0.6720 1.126 5038 2488 49.39933 1553 35.2 59.2 1.9881 1.173 3749 2695 71.90

957 1553 38.5 63.1 2.0073 1.186 3632 2615 72.00

937 1553 35 54 1.9979 1.134 3280 2664 81.21

934 1553 35.4 54.8 1.9889 1.136 3397 2674 78.70Table 5: Results of efficiency calculations

Result:

Following the calculations done based on the previously shown tables, it is calculated that

the average efficiency noted in the combined compressor comes out to be 69% and the

efficiency of the hyper compressor comes out to be approximately 63%.


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PART 2

Heat load Calculations Readings taken:

Combined Compressor

Inlet(C) Outlet(C)

E08 89.6 35.2

E09 92.8 39.6

E10 92.8 30.5

E12 56 35

E13 83.7 43

E14 44 29

Table 6: Temperature readings for K02 coolers

Hyper Compressor INTERSTAGE COOLERS

E15 Inlet(C) Outlet(C)

1 78 63

2 82 63

3 80 62

4 78 63

5 82 62

6 81 62

7 79 65

8 78 66

9 80 67

10 80 65

11 80 64

12 82 63


1 63 34

2 63 35

3 62 35

4 63 33

5 62 35

6 62 34

7 65 37

8 66 36

9 67 39

10 65 36

11 64 35

12 63 35

Table 7: Temperature readings for K03 interstage coolers


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FINAL STAGE COOLERS

Sample Calculations:

Taking the heat load across E08

Step one, value for CP is determined at inlet and outlet conditions using the Aspen property analysisprogram

CP at inlet: 1967 J/kgK

CP at outlet: 1955J/kgK

( )


1 63 70

2 63 70

3 59 54

4 60 54

5 63 53

6 65 53

7 64 48

8 60 489 59 47

10 58 47


3 54 55

4 54 52

5 53 31

6 53 34

7 48 26.4

8 48 25.5

9 47 27

10 47 25

Table 8: Temperature readings for final stage coolers


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Heat load for inter and final stage coolers of the Combined Compressor:

Temperature Cp Flow rate Heat load

Inlet(C) Outlet(C) Inlet(J/kgK) Outlet(J/kgK) M (tph) H(kJ/hr)

E08 89.6 35.2 1967 1955 7 746748.8

E09 92.8 39.6 2341 3651 7 1115710.4

E12 56 35 3952 5001 20 1880130

E13 83.7 43 2922 2801 20 2329261

E14 44 29 2806 2724 20 829500

Table 9: Heat load calculations for K02 coolers

Heat load for inter stage coolers of the Hyper compressor:

E 15 Temperature Cp Flow rate Heat load

Exchanger No. Inlet(C) Outlet(C) Inlet(J/kgK) Outlet(J/kgK) M (tph) H(kJ/hr)

1 78 63 2359 2312 5.833 204356

2 82 63 2371 2312 5.833 259516

3 80 62 2365 2308 5.833 245333

4 78 63 2359 2312 5.833 204356

5 82 62 2371 2308 5.833 272942

6 81 62 2368 2308 5.833 259128

7 79 65 2362 2317 5.833 191059

8 78 66 2359 2320 5.833 163765

9 80 67 2365 2324 5.833 177791

10 80 65 2365 2317 5.833 204838

11 80 64 2365 2314 5.833 218353

12 82 63 2371 2312 5.833 259516


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E 16 Temperature Cp Flow rate Heat load

Exchanger No. Inlet(C) Outlet(C) Inlet(J/kgK) Outlet(J/kgK) M (tph) H(kJ/hr)

1 63 34 2312 2220 5.833 383332

2 63 35 2312 2224 5.833 370440

3 62 35 2308 2224 5.833 356895

4 63 33 2312 2217 5.833 396288

5 62 35 2308 2224 5.833 356895

6 62 34 2308 2220 5.833 369787

7 65 37 2317 2230 5.833 371338

8 66 36 2320 2227 5.833 397863

9 67 39 2324 2236 5.833 372400

10 65 36 2317 2227 5.833 384347

11 64 35 2314 2224 5.833 383839

12 63 35 2312 2224 5.833 370440

Table 10: Heat load calculations for K03 interstage coolers

Heat load for final stage coolers of the Hyper compressor:

E18 Temperature Cp Flow Rate Heat load

Exchanger No. Inlet(C) Outlet(C) Inlet(J/kgK) Outlet(J/kgK) M(tph) H(kJ/hr)

1 63 70 2223 2245 7 -109466

2 63 70 2223 2245 7 -109466

3 59 54 2211 2196 7 77123

4 60 54 2214 2196 7 92610

5 63 53 2223 2193 7 154560

6 65 53 2230 2193 7 185766

7 64 48 2226 2177 7 246568

8 60 48 2214 2177 7 184422

9 59 47 2211 2174 7 184170

10 58 47 2208 2174 7 168707


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E19 Temperature Cp Flow Rate Heat load

Exchanger No. Inlet(C) Outlet(C) Inlet(J/kgK) Outlet(J/kgK) M(tph) H(kJ/hr)

3 54 55 2196 2199 7 -15383

4 54 52 2196 2190 7 30702

5 53 31 2193 2126 7 332563

6 53 34 2193 2135 7 287812

7 48 26.4 2177 2112 7 324248

8 48 25.5 2177 2110 7 337601

9 47 27 2174 2114 7 30016010 47 25 2174 2108 7 329714

Table 11: Heat load calculations for final stage coolers

Result:

As required by objective, the heat loads across all heat exchangers has thus been calculated.

In conclusion,

Interstage coolers for K02:

Final stage coolers for K02: Interstage coolers for K03: Final stage coolers for K03:

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