u083731a zou changlong cooling tower
TRANSCRIPT
THE NATIONAL UNIVERSITY OF
SINGAPORE
Department of Chemical & Biomolecular Engineering
CN4121
Design of Cooling Tower
Name: Zou Changlong U083731A
Data: 19/03/2012
2
Contents
Basic design ....................................................................................5
Computation scheme ......................................................................6
Calculation and results ...................................................................7
Step 1) Driving force and NTU (KaV/L) Calculation .....................7
Step 2) Plot Design NTU Curve .....................................................9
Step 3) Fill Selection ................................................................... 10
Step 4) Optimal L/G value selection............................................. 12
Step 5) Other Calculation............................................................ 17
Appendix ........................................................................................ 21
Reference ........................................................................................ 29
3
Nomenclature
Hot water temperature
Cold water temperature
Wet bulb temperature
Dry bulb temperature
Enthalpy of saturated air, kJ/kg
ℎ Enthalpy of moist air, kJ/kg
Enthalpy of exit air, kJ/kg
Enthalpy of inlet air, kJ/kg
Flowrate,
L Mass flowrate of liquid, kg/h
G Mass flowrate of gas, kg/h
Relative humidity
4
Introduction of cooling towers
The synthesis of ethyl benzene is a very exothermal process. The temperature of raw product is
so high that need to be cooled down to a moderate temperature before it goes to distillation
column or storage. Generally, the excess heat from the synthesis process is transferred to cooling
water. If the temperature is high enough, the heat can also be used to generate steam which can
be used in distillation column or next process. However, most unwanted excess heat has to be
released to the environment without creating ecological hazard and havoc or adding unnecessary
expense by using cooling water as intermedia. Hence, cooling tower is introduced to cool down
the cooling water and recycle it, which not only solve the possible ecological problem caused by
releasing hot water directly to environment but also recycle most water to decrease the
investment of cooling process and do help to the crisis of world’s water supply.
Cooling tower is a thermodynamic artifact combined with a recalculating water system that
serving as a transport medium for heat exchanging between heat source and heat sink. [11]
Cooling towers mainly have two divisions: Nature draft and Mechanical draft.
For Nature draft, the driving force of air flows is attributed by the buoyancy which is cause by
the difference between the densities of warm moist air and dry air. It usually uses very large
concrete chimney which is applied for water flow rates above . [12]
For Mechanical draft, fans are used to force or induce air flow through cooling towers. The
position of fans determines that whether it is forced draft type or induced draft type. The hot
water falls downward over fill surfaces which maximum the contact time between water and air
which maximize heat transfer process.
Cooling towers are also classified into counter flow and cross flow type. However, in theories
and practical, counter flow is more efficiency than cross flow [15]
, because it provides more
contact surface and time.
Cooling tower selection
In Singapore, chemical plan size is limited by the geometry of Singapore which indicates that
small size cooling tower is preferred. The average high temperature and humidity also limit the
5
type of cooling tower. Hence, Nature draft cooling tower is not applicable, because its cooling
efficiency would be very small in high air temperature and humidity, and its size would be very
large in order to fulfill the cooling requirement. For the forced draft type, the back flow of moist
air at top and the big energy request of fans at bottom would be troubles. It can be concluded that
an induced draft counter flow cooling tower is a better choice. The basic structure of this kind of
cooling tower is shown in Figure 1.
Cooling tower design and calculation
Basic design
The designing stream data is according to the Hysys simulating result. The dry air temperature
and relative humidity is according to the literature.[6]
For the determination of cooling water
outlet temperature, the outlet temperature should not excess based on industrial safety
requirement.[12]
Hence, the designing cooling water inlet temperature is set to be after
taking account of 10% safety margin for varying of temperature. With known dry bulb
temperature and relatively humidity, wet bulb temperature of air can be read from Psychrometric
Figure 1, basic structure of cooling tower. a) Fan, b) Water
distribution, c) Fill packing, d) Drift eliminators, e) Cold
water basin, f) Air inlet louver.[1][2][15]
6
figure or calculated by Psychrometric calculator. When dry bulb temperature is , and
relatively humidity is 80%, wet bulb temperature should be . In practical, approach is
seldom closer than . [6][12]
The cooling water outlet temperature is initially set to be
then changed to be based on the calculation of NTUs.
Computation scheme
Step 1: Use the Merkel equation to calculate the
driving force and NTU numbers with an initial guess
L/G ratio.
Step 2: Vary the L/G ratio and redo step one. The
NTU numbers for different L/G ration can be
obtained to generate a demand curve of cooling
tower. (Design NTU curve)
Step 3: Set L/G ratio to be 0.75 and 1.5 and calculate
the volume transfer coefficient (Ka/L) for different
fill types. Then calculate the packed height for
different fill types and select the one which gives the
lowest packed height.
Step 4: Calculate the air loading, pressure drop, fan
power, dimension of tower and etc. for the selected
fill with different L/G ratio. Compare the results and
find out the optimal L/G ratio.
Step 5: Based on the optimal L/G ratio, calculate the
rest information and data for cooling tower.
7
Calculation and results
Capacity (Q): (including 10% safety margin)
Dry bulb temperature of air ( ):
Wet bulb temperature of air ( ):
Relative humidity ( ): 80%
Cooling water inlet ( ):
Cooling water outlet ( ): (initial design )
Altitude (Z): 0 m.
Approach
Heat load
Step 1) Driving force and NTU (KaV/L) Calculation
According to the Merkel theory, the driving force of heat transfer is proportional to the
differences between the enthalpy of saturated air at the water temperature and the enthalpy of
unsaturated air at the point contacting with water.
Forward finite difference method is applied to solve the integration equation. Divide the
temperature range into n small segments so that the integration part can be replaced by[2]
:
Then, the cooling characteristic KaV/L which is a degree of difficulty to cooling can be
approximately calculated.
8
For most cooling tower, evaporation lost is negligible compared to the total amount of cooling
water.[1][2]
Based on this assumption, heat balance for cooling tower can be simplified into:
Therefore
Hence, an equation representing the air operating line of the cooling tower can be obtained:
By using equation (5), any point lying on the air operating line can be calculated.
Combined with saturation curve in Psychrometric, the driving force can be schematized on
Figure 2.
The area enclosed by saturation curve and air operating line is proportional to the total amount of
driving force which equal to the sum of NTU numbers and KaV/L.
Figure 2, Driving force diagram [6][4]
9
Sample calculation:
According to the industrial design, L/G usually is from 0.75-1.5 for counter flow induced draft
cooling tower. KaV/L is usually from 0.5-2.5.[1][6][4]
For initial design:
hw for all temperature points and are calculated by using Psychrometric calculator.(Appendix
1) Then, the rest ha is calculated by equation (5) for all temperature points. NTU numbers for
each temperature can be calculated using equation (2), which can be summed up to calculate
KaV/L. Results are listed in Appendix 2.
The results show that:
This result is out off the normal range of KaV/L values. Besides, when L/G varies slightly
towards to 1.8, sum of NTU numbers shoot up to around 200 and encounter negative value of
NTU during calculation (Appendix 3). This indicates that the cooling water outlet temperature is
too close to the wet bulb temperature which lead to very small driving force for heat transfer.
When L/G increases, the air operating line is getting too close to the saturation curve, even
crossing it at last. It results in big or negative NTU numbers which is not desirable. Considering
such reasons, the cooling water outlet temperature need to be adjusted littler high to decrease
NTU numbers. After some trials, the cooling water outlet temperature is set to be .
Step 2) Plot Design NTU Curve
Repeat step 1 calculation procedure for L/G varying from 0.4 to 2. Use Matlab to do the loop
calculation for different L/G and plot the sum of NTUs against their L/G values respectively.
Results are presented in Appendix 4 and Figure 3.
10
This curve is also known as design NTU curve. For every L/G value, it has an unique NTU and
KaV/L number, which also indicates that the tower characteristic term KaV/L is only influenced
by L/G.[1][2][4][6][9]
Step 3) Fill Selection
Fill is an important structure in cooling tower, because it provides sufficient contacting surface
for air and water to transfer hear. This step aims to choose a better fill from different types of
fills by comparing their packed height for certain L/G. Generally, 16 different arrangements of
triangular splash bars, flat asbestos sheet, corrugated asbestos sheets, rectangular splash bars,
asbestos louvers and typical cellular constructions are commonly used in industry.[2][3]
The
packed height of the tower is calculated directly using the data of Lowe and Christie.[3]
The
volume transfer coefficient Ka/L is represented by the equation:
where and are coefficients that define the transfer characteristics of this type of packing. For
different types of packing, their coefficients are summarized in Table 1.
Figure 3, relation between L/G and KaV/L (NTUs)
11
The details of structure and shape of these fills are presented in Appendix 5. Considering the
industry L/G range 0.75 to 1.5, volume transfer coefficient Ka/L of each type of packing is
calculated for smallest L/G (0.75) and largest L/G (1.5) respectively. According to the results
obtain in Step 2, KaV/L values for each NTU is already known. Then, the packed height can be
calculated by dividing KaV/L by volume transfer coefficient Ka/L just gotten.
For example, when L/G equals 0.75, for type PN-1:
All other result is shown in Appendix 6.
Table 1, coefficients of different packing type [3]
12
Compared with the capital cost caused by tower’s height, the difference between capital costs of
different packing masteries can be negated, which indicates that the height of packing is the
crucial factor. Hence, the best packing type should give the smallest packed heights compared to
others’ at the same L/G value.[7]
After analyzing the result data, it can be found that the packed height V of type PN-11 is the
smallest one for both L/Gs. It can be concluded that PN-11 packing is the best choice for this
cooling tower design. Packed heights of PN-11for other L/G values are listed in Table 2.
L/G NTU(KaV/L) Ka/L V (m)
0.75 1.509326 1.39287468 1.083605
0.8 1.547576 1.33479044 1.159415
0.85 1.588224 1.28243685 1.238442
0.9 1.631519 1.23495867 1.321112
0.95 1.677749 1.19166696 1.407901
1 1.727243 1.152 1.499343
1.05 1.780386 1.11549478 1.596051
1.1 1.837629 1.08176595 1.698731
1.15 1.899501 1.05048996 1.808205
1.2 1.966632 1.02139295 1.925441
1.25 2.039775 0.99424146 2.051589
1.3 2.11984 0.9688351 2.18803
1.35 2.20794 0.94500083 2.336442
1.4 2.30545 0.92258837 2.498893
1.45 2.41409 0.90146651 2.677958
1.5 2.536048 0.88152016 2.876903
Step 4) Optimal L/G value selection
The type of packing is determined to be PN-11. The next main object is to find the optimal L/G
value for the cooling tower.
In design targeting, the objective is to minimize the total cost which consists of capital and
operational cost.[7][10][13]
The capital cost mainly includes cost of tower, fills, fan and pump. The
Table 2, packed heights of PN-11
13
operational cost is mainly contributed by makeup water, operating of fan and pump which is
related directly to their powers.
Calculation of dimensions
The tower floor area is determined by the equation:
where water loading can be approximately determined from Figure 4.
Figure 4, Sizing char for counter flow induced draft cooling tower[6]
The water concentration is .
Tower floor area is:
Then the overall height of tower can be calculated empirically as[3]
:
ℎ ℎ ℎ
For n number of packing cells,
Referring to the industry, the flow rate per cell should less than [10][11], because too
large flow rate will decrease the performance of packing. Considering a big total flow rate of
, it is better to use 6 cells instead of single cell in order to guarantee a good cooling
performance and avoid too big height.[14][15]
Hence, over height for different L/G values from
0.75 to 1.5 can be calculated.
For example, when L/G equals 0.75,
14
ℎ ℎ
Hence the dimensions of cooling tower is , total volume of
tower is:
Other results are listed in Appendix 7.
Operational cost of cooling tower
Calculation of fans’ power
The power of induced fan is determined by the discharge rate Q which represents the amount of
air need to be induced. It can be determined by knowing the total water flow rate through the
tower[3]
.
where TWFR is the total flow rate ( ), is the density of saturated air leaving the tower
( . Then, the horsepower required to drive the fans can be empirically calculated using a
rule of thumb that each 226.5 of air discharged by the fan requires 1 hp, approximately
0.75 kW. The total flow rate is constant. Hence, the power is related to L/G values and saturated
air density at outlet. Assuming the humidity of outlet air is 99%, for different L/G values, the
enthalpy of outlet air is varying, which indicates that temperature is varying according to L/G
values. That leads to different densities for different L/G values. For L/G changes from 0.75 to
1.5 at 0.05 step size, enthalpy of outlet air can be calculated from equation (5) respectively. The
temperature and density can be calculated by trial and error method using Psychrometric
calculator. For example, when L/G equals 0.75
Varying the dry bulb temperature with Psychrometric calculator until the enthalpy is fitted. Then:
15
Hence:
Other results with rest L/G values are listed in Appendix 7&8.
Calculation of Pump’s power
For a counter flow type cooling tower with spray nozzles, the pumping head equals to static lift
plus nozzle pressure drop. The static lift equals to the overall height of tower, which is related to
L/G values will influence pump’s power. The nozzle pressure drop for induced draft tower is
around 0.02MPa to 0.05MPa in industry[8]
, which equals to 2 to 5m water height. Hence, the
nozzle pressure drop for this paper is taken to be 3m water height. Then, the pump’s power can
be calculated as[6]
:
Generally, the efficiency of pump is around 0.5 to 0.65. Then, the pump’s power with respect to
each L/G values can be calculated. For example, when L/G equals 0.75
Other results are listed in Appendix 7&8.
Capital cost of cooling tower
The capital cost of cooling tower includes the capital cost of tower, fill, fan and pump.
According to Turton, these capital cost can be calculated empirically. At ambient operating
pressure and using carbon steel construction, the purchased cost of the equipment can be
calculated from equation (12)[4]
:
where A is the capacity or size parameter of the equipment. The coefficients, maximum and
minimum values used in the correlation are given in that Turton’s book.[4]
For those equipments
16
whose capacity excess maximum values, the costs are calculated based on the maximum capacity
and multiplied by as compensation[4]
.
However, for different working pressures, materials and years, this cost will vary. Hence, in
order to estimate the cost exactly, Pressure factors, Material factor and Bare module factor
should be taken in consideration as an compensation. Then, the capital cost can be expressed as[4]
:
For tower and pumps:
For Fans with electric drives:
For tower packing:
For pressure factors:
The values of the constant , and are given in the book for different materials and type of
tower and pumps. is known for different types of fans and packing. The pressure factors
for all equipments are calculated to be 1, because the operation pressure is not very high which
leads to 0 values of all constant C.[4]
For different L/G values, capacities of different equipments
will be different that will influence the capital costs.
For example, when L/G equals 0.75, the volume of tower is which excess the
maximum values of capacity. Then the capital cost of tower is calculated as:
17
Considering the construction material for cooling tower should has a good resistance to rustiness
and corrosion at highly moist environment, referring to the industrial material of cooling tower,
stainless steel is chosen for this design though it has a higher price than carbon steel. Then:
Other capital costs of equipments are list in Appendix 8.
Total cost of cooling tower
Assuming 10 year and 8000 hours per year operation time, the total cost of overall cooling tower
can be estimated with respect to L/G values from 0.75 to 1.5. Data is listed in Appendix 8. The
relation between L/G values and total cost is represented on Figure 5.
It can be found that the lowest cost appear when L/G equals 1.2. Then, it can be determined that
the optimal design L/G is 1.2.
Step 5) Other Calculation
When L/G is 1.2, other details can be calculated easily.
For makeup water, the amount can be calculated by a empirical equations:[1][6]
Figure 5, L/G vs. total cost
18
where is makeup water, is circulation water, is evaporation loss, is drift loss and
is blown down. For this design of cooling tower, Newater is used as cooling water, because
Newater contains less amount of chlorate and salts which contributes to less corrosion and larger
cycles’ number (about 10). Besides, Newater is recommended by Singapore government for the
purpose of saving water resources. Then, makeup water is calculated as:
For pressure drop across the packing: [3][13]
For PN-11 type,
19
Details of Cooling Tower
Capacity 5400
Range 13 Relative
outlet
humidity
99% Air Flow
rate
1184.68
Density of
water
998.1
Approach 4.2 L/G 1.2 Pressure
Drop across
fill
66.4 Pa
Dry bulb
temperature
of air (inlet)
Effectiveness 75.58% KaV/L 1.967 Enthalpy of
air (inlet)
92.9
kJ/kg
Wet bulb
temperature
of air (inlet)
Cell width 11.54m Floor area 799.68 Enthalpy of
air (outlet)
158.20
kJ/kg
Relative
inlet
humidity:
80% No. of cells 6 Volume 15387.76 Fan power 235.37
kW
Cooling
water inlet
( ):
Tower Width 23.09m Water
Loading
6739.89
Pump power 502.07
kW
Cooling
water outlet
( ):
Tower Length 34.63m Air velocity
across
packing
1.42
Capital cost
Altitude (Z): 0 m Tower Height 19.24 m Density of
air at Fan
1.05
Operational
cost(10 year)
Heat load
Packed height 1.925m Dry bulb
temperature
of air
(outlet)
39.2 Total cost
20
Cell 11.54 m
Width 23.09 m
Length 34.63 m
Height 19.24 m
Height 19.24 m
Appendix
Appendix 1
For saturated air
Temperature( ) Hw(kJ/kg
30 99.6709
30.5 102.3102
31 105.0097
31.5 107.7712
32 110.5962
32.5 113.4866
33 116.444
33.5 119.4703
34 122.5674
34.5 125.7371
35 128.9816
35.5 132.3028
36 135.7028
36.5 139.1839
37 142.7482
37.5 146.3981
38 150.1359
38.5 153.9642
39 157.8854
39.5 161.9021
40 166.0171
40.5 170.2332
41 174.5532
41.5 178.9801
42 183.517
42.5 188.167
43 192.9335
43.5 197.8198
44 202.8295
44.5 207.9662
45 213.2337
Length 34.63m
Height 19.24m
Height 19.24m
Length 34.63m
Height 19.24m
Height 19.24m
Width 23.09m
22
Appendix 2
Temperature ( ) Ha (kJ/kg) Hw (kJ/kg) Hw-Ha (kJ/kg) 1/(Hw-Ha) (kg/kJ) NTU
30 92.9 99.6709 6.770901 0.147691
30.5 96.0395 102.3102 6.27066 0.159473 0.321447
31 99.179 105.0097 5.830707 0.171506 0.346369
31.5 102.3185 107.7712 5.452666 0.183397 0.371405
32 105.458 110.5962 5.138209 0.19462 0.395595
32.5 108.5975 113.4866 4.889054 0.204539 0.417720
33 111.737 116.444 4.706972 0.212451 0.436379
33.5 114.8765 119.4703 4.593782 0.217686 0.450138
34 118.016 122.5674 4.551361 0.219714 0.457739
34.5 121.1555 125.7371 4.581639 0.218263 0.458343
35 124.295 128.9816 4.686602 0.213374 0.451708
35.5 127.4345 132.3028 4.86830 0.205411 0.438258
36 130.574 135.7028 5.128841 0.194976 0.419004
36.5 133.7135 139.1839 5.470399 0.182802 0.395345
37 136.853 142.7482 5.895216 0.169629 0.368819
37.5 139.9925 146.3981 6.405602 0.156113 0.340889
38 143.132 150.1359 7.003938 0.142777 0.312789
38.5 146.2715 153.9642 7.692683 0.129994 0.285454
39 149.411 157.8854 8.474372 0.118003 0.259528
39.5 152.5505 161.9021 9.351621 0.106933 0.235396
40 155.69 166.0171 10.32713 0.096832 0.213241
40.5 158.8295 170.2332 11.40369 0.087691 0.193104
41 161.969 174.5532 12.58418 0.079465 0.174928
41.5 165.1085 178.9801 13.87158 0.07209 0.158602
42 168.248 183.517 15.26896 0.065492 0.143980
42.5 171.3875 188.167 16.7795 0.059597 0.130906
43 174.527 192.9335 18.40649 0.054329 0.119223
43.5 177.6665 197.8198 20.15332 0.04962 0.108782
44 180.806 202.8295 22.02352 0.045406 0.099444
44.5 183.9455 207.9662 24.02073 0.041631 0.091084
45 187.085 213.2337 26.14871 0.038243 0.083588
8.679205
23
Appendix 3
Temperature ( ) Ha (kJ/kg) Hw (kJ/kg) Hw-Ha (kJ/kg) 1/(Hw-Ha) (kg/kJ) NTU
30 92.9 99.6709 6.770901 0.147691
30.5 96.6674 102.3102 5.64276 0.177218 0.340017
31 100.4348 105.0097 4.574907 0.218584 0.414207
31.5 104.2022 107.7712 3.568966 0.280193 0.52197
32 107.9696 110.5962 2.626609 0.380719 0.691645
32.5 111.737 113.4866 1.749554 0.571574 0.996575
33 115.5044 116.444 0.939572 1.064315 1.711958
33.5 119.2718 119.4703 0.198482 5.03823 6.386313
34 123.0392 122.5674 -0.47184 -2.11937 3.054588
34.5 126.8066 125.7371 -1.06946 -0.93505 -3.19645
35 130.574 128.9816 -1.5924 -0.62798 -1.63572
35.5 134.3414 132.3028 -2.0386 -0.49053 -1.17053
36 138.1088 135.7028 -2.40596 -0.41563 -0.9483
36.5 141.8762 139.1839 -2.6923 -0.37143 -0.82366
37 145.6436 142.7482 -2.89538 -0.34538 -0.75014
37.5 149.411 146.3981 -3.0129 -0.33191 -0.70878
38 153.1784 150.1359 -3.04246 -0.32868 -0.6913
38.5 156.9458 153.9642 -2.98162 -0.33539 -0.69495
39 160.7132 157.8854 -2.82783 -0.35363 -0.72106
39.5 164.4806 161.9021 -2.57848 -0.38783 -0.77593
40 168.248 166.0171 -2.23087 -0.44826 -0.87496
40.5 172.0154 170.2332 -1.78221 -0.5611 -1.05629
41 175.7828 174.5532 -1.22962 -0.81326 -1.43827
41.5 179.5502 178.9801 -0.57012 -1.75402 -2.68666
42 183.3176 183.517 0.199361 5.016023 3.413685
42.5 187.085 188.167 1.082001 0.924213 6.216458
43 190.8524 192.9335 2.081089 0.480518 1.470051
43.5 194.6198 197.8198 3.200024 0.312498 0.829891
44 198.3872 202.8295 4.442324 0.225107 0.562604
44.5 202.1546 207.9662 5.81163 0.172069 0.415645
45 205.922 213.2337 7.311712 0.136767 0.323196
9.1758
24
Appendix 4
L/G NTU
0.4 1.293297
0.45 1.319627
0.5 1.347266
0.55 1.376323
0.6 1.406915
0.65 1.439176
0.7 1.473257
0.75 1.509326
0.8 1.547576
0.85 1.588224
0.9 1.631519
0.95 1.677749
1 1.727243
1.05 1.780386
1.1 1.837629
1.15 1.899501
1.2 1.966632
1.25 2.039775
1.3 2.11984
1.35 2.20794
1.4 2.30545
1.45 2.41409
1.5 2.536048
1.55 2.67415
1.6 2.832122
1.65 3.014988
1.7 3.22971
1.75 3.486246
1.8 3.799422
1.85 4.19243
1.9 4.70394
1.95 5.404212
2 6.437482
25
Appendix 5
26
Appendix 6
Type L/G m Ka/L NTU V
PN-1 1.5 0.295 0.5 0.240866 2.536048 10.52885
PN-2 1.5 0.236 0.47 0.195051 2.536048 13.00194
PN-3 1.5 0.288 0.7 0.216835 2.536048 11.69577
PN-4 1.5 0.459 0.73 0.341402 2.536048 7.428332
PN-5 1.5 0.276 0.49 0.226269 2.536048 11.20813
PN-6 1.5 0.689 0.69 0.520854 2.536048 4.869015
PN-7 1.5 0.36 0.66 0.275475 2.536048 9.206088
PN-8 1.5 0.558 0.58 0.441064 2.536048 5.749845
PN-9 1.5 0.243 0.52 0.196806 2.536048 12.88601
PN-10 1.5 0.666 0.7 0.50143 2.536048 5.05763
PN-11 1.5 1.152 0.66 0.88152 2.536048 2.876903
PN-12 1.5 0.331 0.63 0.256384 2.536048 9.891608
PN-13 1.5 0.282 0.52 0.228392 2.536048 11.10391
PN-14 1.5 1.01 0.8 0.730211 2.536048 3.473034
PN-15 1.5 0.814 0.79 0.590898 2.536048 4.291855
PN-16 1.5 0.99 0.45 0.824886 2.536048 3.074421
PN-1 0.75 0.295 0.5 0.340637 1.509326 4.430898
PN-2 0.75 0.236 0.47 0.270168 1.509326 5.586631
PN-3 0.75 0.288 0.7 0.352249 1.509326 4.28483
PN-4 0.75 0.459 0.73 0.566263 1.509326 2.665417
PN-5 0.75 0.276 0.49 0.317782 1.509326 4.749568
PN-6 0.75 0.689 0.69 0.840286 1.509326 1.796206
PN-7 0.75 0.36 0.66 0.435273 1.509326 3.467537
PN-8 0.75 0.558 0.58 0.659324 1.509326 2.289204
PN-9 0.75 0.243 0.52 0.282211 1.509326 5.348214
PN-10 0.75 0.666 0.7 0.814576 1.509326 1.852899
PN-11 0.75 1.152 0.66 1.392875 1.509326 1.083605
PN-12 0.75 0.331 0.63 0.396771 1.509326 3.804029
PN-13 0.75 0.282 0.52 0.327504 1.509326 4.608567
PN-14 0.75 1.01 0.8 1.271371 1.509326 1.187164
PN-15 0.75 0.814 0.79 1.021706 1.509326 1.477261
PN-16 0.75 0.99 0.45 1.126828 1.509326 1.339447
27
Appendix 7
L/G KaV/L
Packed
Height (m)
Packed
Volume( )
Total
Height (m)
Total
Volume
Width of
cell (m)
0.75 1.5093 1.0836 866.5354 18.4006 14714.5778 11.5447
0.80 1.5476 1.1594 927.1587 18.4764 14775.2011 11.5447
0.85 1.5882 1.2384 990.3550 18.5555 14838.3974 11.5447
0.90 1.6315 1.3211 1056.4646 18.6381 14904.5070 11.5447
0.95 1.6777 1.4079 1125.8672 18.7249 14973.9096 11.5447
1.00 1.7272 1.4993 1198.9914 18.8164 15047.0338 11.5447
1.05 1.7804 1.5961 1276.3268 18.9131 15124.3692 11.5447
1.10 1.8376 1.6987 1358.4378 19.0158 15206.4802 11.5447
1.15 1.8995 1.8082 1445.9820 19.1252 15294.0244 11.5447
1.20 1.9666 1.9254 1539.7330 19.2425 15387.7754 11.5447
1.25 2.0398 2.0516 1640.6105 19.3686 15488.6529 11.5447
1.30 2.1198 2.1880 1749.7192 19.5051 15597.7616 11.5447
1.35 2.2079 2.3364 1868.4017 19.6535 15716.4441 11.5447
1.40 2.3054 2.4989 1998.3099 19.8159 15846.3523 11.5447
1.45 2.4141 2.6780 2141.5046 19.9950 15989.5470 11.5447
1.50 2.5360 2.8769 2300.5958 20.1939 16148.6382 11.5447
L/G G (kg/h) G ( ) ( ) ( (kJ/kg) velocity(m/s)
0.75 7186320.0000 1852.4381 1.0776 35.8600 133.7135 2.2693
0.80 6737175.0000 1741.3860 1.0747 36.2700 136.4344 2.1275
0.85 6340870.5882 1643.2349 1.0719 36.6600 139.1553 2.0023
0.90 5988600.0000 1555.8283 1.0692 37.0300 141.8762 1.8911
0.95 5673410.5263 1477.8689 1.0664 37.4200 144.5971 1.7916
1.00 5389740.0000 1407.3629 1.0638 37.7700 147.3180 1.7020
1.05 5133085.7143 1343.9839 1.0609 38.1600 150.0389 1.6209
1.10 4899763.6364 1285.9578 1.0584 38.5000 152.7598 1.5473
1.15 4686730.4348 1233.1860 1.0557 38.8600 155.4807 1.4800
1.20 4491450.0000 1184.6782 1.0531 39.2000 158.2016 1.4183
1.25 4311792.0000 1140.0825 1.0506 39.5400 160.9225 1.3616
1.30 4145953.8462 1098.9487 1.0480 39.8800 163.6434 1.3092
1.35 3992400.0000 1061.0487 1.0452 40.2400 166.3643 1.2607
1.40 3849814.2857 1025.3551 1.0429 40.5300 169.0852 1.2157
1.45 3717062.0690 992.3678 1.0405 40.8500 171.8061 1.1738
1.50 3593160.0000 961.5328 1.0380 41.1600 174.5270 1.1347
28
Appendix 8
L/G Tower Capital($)
Packing
Capital($) Fan Capital($)
Pump
Capital($)
Fan
Power(kW)
Pump
Power(kW)
0.75 28061904.12 338495.46 1850898.75 280916.84 368.03 483.06
0.80 28131215.21 362135.59 1783501.44 281513.49 345.97 484.78
0.85 28203347.07 386784.43 1722488.06 282134.56 326.47 486.56
0.90 28278672.76 412575.59 1666914.95 282783.30 309.10 488.42
0.95 28357606.82 439658.16 1616285.15 283463.28 293.62 490.38
1.00 28440615.53 468200.59 1569567.86 284178.55 279.61 492.45
1.05 28528229.23 498395.23 1526767.42 284933.71 267.02 494.63
1.10 28621057.34 530464.03 1486868.14 285734.05 255.49 496.95
1.15 28719807.20 564665.62 1449951.90 286585.70 245.00 499.42
1.20 28825308.02 601304.44 1415456.96 287495.86 235.37 502.07
1.25 28938541.66 640742.47 1383242.11 288473.07 226.51 504.91
1.30 29060683.18 683414.82 1353078.18 289527.54 218.33 507.99
1.35 29193154.66 729850.45 1324883.28 290671.63 210.80 511.34
1.40 29337698.29 780700.55 1297959.15 291920.51 203.71 515.01
1.45 29496477.08 836777.83 1272740.96 293293.00 197.16 519.05
1.50 29672216.95 899112.28 1248863.25 294812.85 191.03 523.54
L/G Capital Cost(S$)
Operational
Cost(S$) Total Cost(S$)
0.75 38394260.57 17164942.95 55559203.53
0.80 38427144.90 16754481.16 55181626.06
0.85 38472903.32 16397177.00 54870080.32
0.90 38530990.34 16084583.73 54615574.07
0.95 38601494.36 15811718.56 54413212.92
1.00 38683922.38 15570837.13 54254759.51
1.05 38779194.43 15360910.19 54140104.62
1.10 38887085.37 15175149.91 54062235.27
1.15 39008920.61 15013536.72 54022457.33
1.20 39145428.34 14872541.74 54017970.07
1.25 39298131.63 14751279.32 54049410.95
1.30 39468779.91 14648574.26 54117354.17
1.35 39659739.23 14564276.65 54224015.87
1.40 39873160.20 14495210.80 54368371.00
1.45 40113355.75 14444551.84 54557907.59
1.50 40384619.20 14411566.90 54796186.11
29
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