Assignment 3 of Casein Plant Design2

7/29/2019 Assignment 3 of Casein Plant Design2

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UNIVERSITAS INDONESIA

PRELIMINARY DESIGN OF CASEIN PLANT FROM SKIM MILK

PLANT DESIGN REPORT

ASSIGNMENT 3

GROUP 10

ADI KHAFIDH PERSADA 0906640702

FITRI ANISA 0906557871

LATIFANI AYU CHAERUNNISA 0906640822

MUHAMMAD IKHLAS 0906489896

PIJAR RELIGIA 0906557953

ENGINEERING FACULTY

BIOPROCESS ENGINEERING STUDY PROGRAM

DEPOK

SEPTEMBER 2012


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CHAPTER 5

HEAT EXCHANGER NETWORK AND UTILITY UNIT ANALYSIS

We need a heat to make a casein in a casein plant which the heat needs the big energy, so

we must make a plant to optimize the energy so that energy in our plant can be efficiently. To

save energy optimally, we can calculate Heat Exchanger Network (HEN). The purpose of

HEN calculating is to know the minimum of heat exchanger that is needed. The amount of

heat exchanger is affecting the minimum utility for temperature differences that is predicted.

Besides that, the calculating of HEN is also needed to know the cold utility is needed. To

calculate of Heat Exchanger Network (HEN), we must follow this procedure:

Determining the cold and hot stream Calculating the stream spesification and determining of Tmin Making of population streams Making of cascade diagram

To know about the calculating of HEN, we can calculate one by one of the procedure above:

1.1 Heat Exchanger Network

a. Determining The Cold and Hot streams

In the first step, we can determine the cold and hot stream from the super pro data.The cold and hot stream data from super pro data can be looked in table below:

Table 1.1. Hot Streams Data of Casein Plant

Number Stream Ts Tt Condition

1 R2 78 35 Hot

Table 1.2. Cold Streams Data of Casein Plant

Number Stream Ts Tt Condition

1 R1 25 40 Cold

2 R2 35 78 Cold

3 W1 25 65 Cold

4 W2 25 45 Cold

b. Calculating The Stream Spesification and Determining of Tmin

To calculate the stream spesification in our casein plant, we can use this formula below:

Assumption:Tmin : 10 C


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The Cp data is getting from process simulation in Hysys dan Super Pro software program.

To find the target and supply temperature for our heat utility in cold and hot streams can be

found with this formula:

For Hot Stream =

1

2 (3.1)

= 1

2 (3.2)

For Cold Stream = +

1

2 (3.3)

= +1

2 (3.4)

where Ts is supply temperature (C) and Tt is target temperature (C). For each hot and coldstream in our plant can be looked in the table below:

Table 1.3. Streams Spesification

Nama Condition kg/h Cp (KJ/kgC) Cp Q (kJ/h)

R1 cold 11200 4,2 47040,00 7,06E+05

R2 hot 12440 1,52 18908,80 8,13E+05

R2 Cold 12440 1,52 18908,80 8,13E+05

W1 cold 4309 4,2 18097,80 7,24E+05

W2 Cold 4088 4,2 17169,60 3,43E+05

Tabel 1.4. Supply and Target Temperature

Nama ConditionCp

(KJ/kgC)Ts(C) Tt(C) Ts* Tt* Tm (C)

R1 cold 4,2 25 40 30 45 10

R2 hot 1,52 78 35 73 30 10

R2 Cold 1,52 35 78 40 83 10

W1 cold 4,2 25 65 30 70 10

W2 Cold 4,2 25 45 30 50 10

After making the stream spesification, we can make a stream population to know thehot and cold stream distribution at the temperature something.

c. Making Of Stream Population

The temperature difference (H) is getting from this formula:

= (3.5)

From the formula above, if H interval has a positive value, it is called a deficit. But, if

H interval has a negative value, it is called a surplus.


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Figure 5.1. Stream Population Graphic

Stream population graphic is shown the hot and cold stream phenomenans in the

temperature range something. This graphic is using to calculate the value of Q (calor) which

is transmitted in the range of temperature where the value of Q will be used in cascade

diagram.

d. Making Of Cascade Diagram

Cascade diagram shows the clear energy in temperature interval. Cascade process can

be done during the energy can be transferred with the temperature gradient differences into

the temperature level below. From the cascade diagram, the needing of hot and cold utility

can be calculated based on energy distribution in each temperature interval. To know

furtherly about the cascade diagram in our casein plant, we can look in the figure below:

Interval Temp (C) T (C) CpC-CpH H interval (MW) Surplus/defisit

83

78 78 10 0,0 0 defisit

733 0,0 0 defisit

70

65 20 0,0 0 defisit

50

5 1,2 6 defisit

45

5 5,4 27 defisit

4035 35 10 12,6 126 defisit

30

25 25 25

Stream Population

cp4,2

cp1,52

cp1,52

cp4,2

cp4,2


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Figure 1.4. Cascade Diagram

From the cascade diagram above for heat exchanger network in our casein plant, we

conclude that we need a hot and cold utility. It can look from the hot utility line where the hot

utility in our plant is 126 MW atau sekitar 8,13 x 105 kJ/h. Besides that, the cold utility in our

plant is 33 MW atau sekitar 3,15 x 105 kJ/h. From the curve above, the pinch node in our

casein plant is 500C and 70

0C . So, our group decide the pinch node in our casein plant is

500C. After make the scheme, the grand composite curve can be made. This curve is to

determine utility type that will be used. The curve is:

Figure 1.5. Grand Composite Curve

From figure above it can be seen that hot utility is needed to increase temperature of

cold stream process. In this case, we need utility to fulfill the hot stream.

hot utility

83 0 MW

H = 0

73 0 MW

H = 0

70 0 MW

H = 0

50 0 MW

H = 6

45 -6 MW

H = 27

40 -27 MW

H = 126

30 -126 MW

cold utility

hot utility

83 126 MW

H = 0

73 126 MW

H = 0

70 126 MW

H = 0

50 126 MW

H = 6

45 120 MW

H = 27

40 93 MW

H = 126

30 -33 MW

cold utility

0

10

20

30

40

50

60

70

80

90

-50 0 50 100 150

Te

mperature(oC)

H (MW)

Grand Composite Curve

Grand

Composite


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1.2 Utility

1.2.1 Water Utility

Water supply system is needed to support the sustainability of the production plant.

Utility water is required as process water, cooling water in heat exchanger systems, boiler

feed water, equipment wash water and domestic water needs. The design of the water supply

system based on the ease of water collection, treatment system efficiency and economic

factors. In the casein plant used several types of water, namely, process water, cooling water,

boiler feed water, equipment wash water, domestic water and fire water. Can be explained as

follows:

1.2.1.1Water Utility Classification

a. Process Water

Most of the water used in the dissolution and dilution systems. In unit steam

explosion, water is required to dissolve sulfuric acid for coagulation process. Besides that,

process water is used in the last step of washing tank. Capacity of water needed in the process

in an casein plant is at 30255,22 kg/day.

b. Cooling Water

Cooling water system is used to maintain the temperature in the washing reactor. All

water used in the cooling system using water at ambient temperature is assumed to be 25oC.

Ice water is the most common form of cooling water used in dairies. Water is cooled in an ice

water tank where ice is formed on in chiller. The source of cooling water is come from the

PT. KIJA. The need for cooling water at the plant reached 156,97 kg/day. The cooling water

is needed in our plant can look in the table below:

Tabel 2.1.1.2. Cooling Water In Our Plant

Unit Cooling water needs (kg/h)

Acidification unit 117,28

Plate Heat Exchanger 39,69

Total 156,97

c. Domestic Water

This water is used to meet the water needs of the staff and factory workers. Domestic

water includes water MCK (bathing, washing, toilet), drinking water, water for watering

plants and other water needs. Assumed domestic needs for each person is 100 liters/day.

Thus, the total water needed for domestic water is 10,000 liters/day.


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d. Water Fire Extinguisher

Firefighting water used to extinguish the fire in case of fire. Water is one of the water

reserves that can be used at any time. Firefighting water used was water with the low specs,

but has undergone treatment first. The amount of water required for fire is assumed to 10,000

kg /day.

e. Water Resources

Water supply to the plant will be taken from Jababeka industrial area manager, PT.

KIJA. PT. KIJA independently manage all water providers to the needs of industries that

exist within the industry. Water supplied by PT. KIJA is considered clean enough and qualify

for use as water for industrial plants. So in the factory there is no clean water management

facilities further.

So, the total amount of water utility in our plant is 50412,196 kg/h or 50412,196

L/day.

1.2.2 Gas Utility

Gas Utility is need to make an air for spray drying. It comes from compressor. In

compresor, the refrigerant vapour is compressed to a high pressure in the compressor. This

increases the temperature of the vapour. The work carried out by the compressor is

transferred to the gas in the form of heat. This means that the gas leaving the Compressor

contains a greater quantity of heat than was absorbed in the evaporator. All this heat must

therefore be removed by cooling in the condenser. The most commonly used refrigerating

compressor is the piston compressor. The gas is drawn into cylinders and compressed by

pistons in the cylinders. The machines can be equipped with a varying number of cylinders.

They are available for refrigerating capacities between 0,1 and 400 kW. The screw

compressor (Figure 2.4), is also very common nowadays, especially for higher capacities.

The principal components are two helical rotors installed in a common housing. As the rotors

turn, gas is drawn into the gaps between the teeth and is trapped in the clearances. The

volume between the teeth is progressively reduced as the captive gas is conveyed along the

length of the rotors, so the gas is gradually compressed and the pressure increases. The

compressed vapour continues to the condenser. Oil is sprayed on the meshing faces in most

screw compressors in order to reduce leakage between the gaps in the rotors. In this way it is

possible to obtain high efficiency even at low speeds. The oil is removed from the vapour in

an oil trap before the condenser. Screw compressors are used in large installations. One of the

greatest advantages of the screw compressor is that the capacity can be varied down to 10 %

of full power without excessive electric power losses.


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Figure 2.4. Screw Conveyor

Source: Dairy Proceesing Handbook

Generally, diesel is used as fuel material in screw compressor. We can assumed that

efficient in screw conveyor as 40%. So, the fuel utility in the screw compressor is :

0,4 m = needing calor/heating value of fuel

0,4 m = 33875 J/0,00334 J/l

m = 25355538 ,92 l

1.2.3 Steam UtilityGeneration of the heating medium takes place in steam boilers which are sometimes

located in the heating plant. The boiler is usually fuelled with oil, coal or gas. Thermal energy

is released by the burning fuel and absorbed by the heating medium. The efficiency of the

boiler is in the range of 8092 %, and heat losses in the piping system often amount to about

15 %. Consequently, only between 65 and 77 % of the total thermal energy of the fuel can be

utilised in production. From the point of view of operating costs, it is most important that the

efficiency of the boiler does not drop below the minimum level, and for this reason, boiler

efficiency is very closely checked in the dairy. The steam temperature in the steam system

described below must be between 140 and 150 C. In the case of saturated steam, this is

equivalent to a gauge pressure of 270 385 kPa (2,7 3,8 bar). The boilers operate at a

considerably higher pressure, as a rule 900 1 100 kPa (9 11 bar), so that smaller piping

dimensions can be used to compensate for heat and pressure losses in the system.

Figure 2.1 is a simplified diagram of the steam system and the distribution network.

The water used for generation of steam is referred to as feed water. Makeup water often

contains calcium salts, which make the water hard. Treatment of feed water is often


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necessary, as it contains oxygen and carbon dioxide. If this is not done, the salts will be

deposited in the system and form scale in the boiler, resulting in drastically reduced

efficiency. Oxygen can cause severe corrosion in the water and steam parts. Water-softening

filters (10) are therefore included in the system. They remove the calcium and magnesium

salts, and a de-gassing apparatus (11) removes the gases in the feed water. Impurities in the

form of sludge are removed by blowing down the boiler. Chemical conditioning of boiler

water and treatment of boiler feed water are necessary to keep the steam system in good

operating condition.

Figure 2.1. Steam Production and Distribution Steam

Source: Dairy Processing Handbook

A feed water pump keeps the water in the boiler at a constant level. The water in the

boiler is heated by the burning fuel and converted to steam. It takes a great deal of heat, about

2 260 kJ (540 kcal) at atmospheric pressure, to convert one kilogram of water to steam. This

heat, which is referred to as vaporisation heat, will subsequently be released as the steam

Notes:


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condenses on the heat transfer surfaces at the points of consumption (5). The condensed

steam, condensate, is collected in steam traps (6) and a condensate tank (7) and pumped back

to the boiler by a condensate pump.

Two main types of boilers are used for the generation of steam: the fire tube boiler

(which is the most common type in dairies) and the water tube boiler. The choice is

influenced by the required steam pressure and steam power, i.e. the quantity of steam utilised

at a given time. Boilers for low pressures and small power outputs are often tubular boilers in

which the flue gases pass inside the tubes. Boilers for high pressures and large steam power

outputs are mostly water-tube boilers, in which the water is circulated inside the tubes.

Figure 2.2 shows the principle of the fire tube boiler. The hot flue gases are blown by a fan

through the tubes. Heat from the flue gases is conducted through the walls of the tubes to the

water surrounding the outside of the tubes. The water is heated to boiling point and the steam

is collected in the steam dome for distribution to the system.

Figure 2.2. Fire Tube Boiler


When the pressure inside the steam dome reaches the required (pre-set) level, the

steam valve can be opened and the steam flows to the points of consumption. The burner is

started and stopped automatically, keeping the steam pressure at the required level. Feed

water is added so that the correct water level is maintained in the boiler. The safety valve

opens if the highest permitted pressure in the steam dome is exceeded.

Water-tube boilers (Figure 2.3) are available in a wide range of models. The principle

is that the feed water passes through tubes which are externally heated by the flue gases.

Steam generation takes place in the tubes, which are inclined so that the steam can rise to the

steam dome. The steam passes into the two upper domes via the superheater before being fed

into the distribution system. The steam is heated by the flue gases for a second time in the


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superheateri.e. the steam is superheated, and becomes dryer as a result. The lower dome also

collects sediment sludge, the impurities which were present in the feed water. The sludge is

removed from this dome by bottom-blowing the boiler. In other types of boilers, the sludge

collects in the bottom of the boiler.

Figure 2.3. Water-Tube Boiler


The steam which passes through the piping system is cooled by the surrounding air

and consequently starts to condense. It is possible to reduce this condensation by insulating

the pipes, but condensation can never be completely avoided. The pipes must therefore be

installed with a slight slope towards the condensate collection points, which are located in

various parts of the piping system. Steam traps are installed at these points. They permit the

condensate to pass (and preferably also air), but not steam. The condensate is collected in the

same way at the various steam consumption points and is returned to a collecting tank in the

heating plant by condensate pumps and a piping system. Condensate can be returned to the

feed water tank by steam pressure without using a condensate tank or condensate pump. This

system is very often used.


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Figure 2.4. Stream Distribution


Generally, the fuel which is used in boiler is diesel. It is assumed that the steam

required in the plant is entirely derived from fossil material. It is assumed that the boiler used

to use diesel as fuel. It is assumed that the efficiency of the boiler which is owned by the

boiler plant is 40%. Thus, the diesel fuel used to generate steam in the plant is equal to:

0,4 m = needing calor/heating value of fuel

0,4 m = 33875J/0,00334 J/l

m = 25355538 ,92 l

1.2.4 Electricity Utility

As the plant in general, to run the equipment contained in the bioethanol plant

required no small amount of energy. Equipment that requires a supply of energy, among

others:

Pump Plate Heat Exchanger Washing Tank Centrifugal Decanter Spray Drying Conveyor


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Electric needs at the casein plant can be seen in the following table:

Table 2.1. Needing Energy In Casein Plant

Demand Of Energy Hp kw kwh

Pump For Mixing Tank P-101 1 0,74 17,89

Pump For Dilution Of HCl P-102 0,5 0,37 8,94

Pump For Washing Tank P-103 0,5 0,37 8,94

Pump For Washing Tank P-104 0,5 0,37 8,94

Pump For Milk P-105 2 1,49 35,79

Pump For Curd Casein P-106 2 1,49 35,79

Plate Heat Exchanger 35444,11 26430,68 634336,32

Heat Exchanger 1 2,3 55,2



Washing Tank 1 0,01 0,01 0,24

Washing Tank 2 0,01 0,01 0,24

Mixing Tank 1,34 1 24

Decanter 1 170,89 127434 2986,42

Decanter 2 170,89 127,434 2986,42

Decanter 3 170,89 127,434 2986,42

Fan Spray Drying 4,80 3,58 143,2

Spray Drying 8,74 5 120

Pneumatic Conveyor 1 2,68 2 48



HCl Storage Tank 1,34 1 24

Water Storage Tank 1,34 1 24

Total kebutuhan listrik untuk proses 644057,15

Electricity is needed on the basis of casein plant from skim milk is a power type AC

(accuired current). The power requirement of the plant's total amounted to 644057,15 kWh /

day. While supporting the need for lighting and other assumed 5% of the total energy that is

32202,85 kwh / day. So the total electricity needs of the bioethanol plant 676260,01 kWh for

each day.

Electrical power is largely used for two main purposes. The first necessity that

requires electrical power is the need of the production process. The second purpose is to use

the power of production support facilities. Power to support facilities used for lighting andair-conditioning (AC) in the office, laboratory, workshop and control room, air supply (tap


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and clean), water supply (and the net), and the sewage treatment plant. Electricity in casein

plant is supplying from PT. Cikarang Listrisindo. To know about the all of utility in our plant

can be showed in table below:

Table 2.2. The Utility Of Casein Plant

Utility Source Demand per year

Water PT. KIJA 50412,196 kg/h

Electricity PT. Cikarang Listrisindo 676260,01 kWh

Diesel Pertamina 50711,07 Kl


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References:

Albert, Johan. 1991. Centrifugal Decanter Handbook. Newyork: McGraw Hill Book Co.

Paundhitro, Slamet. 2008. Spray Drying Handbook. Newyork: McGraw Hill Book Co.

Robert, Kevin. 2008. Unit Operation Of Chemical Engineering. Newyork: McGraw HillBook Co.

Smith, Julian 2008. Dairy Processing Handbook.. Newyork: McGraw Hill Book Co.

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Assignment 3 of Casein Plant Design2