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Material Balance
Hydrotreater Reactor
In CPC specification does not provide data for total sulfur (Mercaptans, Disulfides, Sulfides +
thiophenes, sulfur, Polysulfide) available in naphtha feed. It just represents sulfur content and hydrogen
sulfide content in the naphtha feedstock. It is assumed that amount of total sulfur is equal to the sulfur
content in the naphtha feedstock.
(http://www.ceypetco.gov.lk/Ceypetco_Products.htm#CP19)
Hydrotreater
Inlet flow rates to the Hydrotreater
Naphtha
Naphtha feed rate =245.45MT/day
Hydrogen
For hydrotreating of naphtha Hydrogen(nm 3)hydrocarbon(m 3) should be 100 is desired.
(A design report on catalytic hydrotreating OF 4500 bbl / day,(30 m3/hr) of raw naphtha, Engr. Waqar
Ali Khan,page-16)
Density of naphtha = (650+720)/2
= 685 kgm-3
Therefore, volumetric flow rate of naphtha =245.45×1000
685
= 358.33m3/Day
Therefore, Required Hydrogen flow rate = 358.33 x 100
= 35833 m3/Day
Hydrogen Mass flow rate for hydrotreating naphtha =35833 x 0.081/1000
= 2.9MT/Day
Sulfur
Amount of sulfur in naphtha = 50ppm or 50mg/kg
Amount of sulfur in feed = 245.45×1000×50
1×106
Sulfur feed rate = 12.273kg/Day
Calculation for Outlet Flow Rates
The objective of Naphtha hydrotreating in naphtha steam reforming process is to reduce sulfur up to or
less than 0.5ppm
Let, Sulfur content in product is 0.2ppm
Percentage of sulphur in the product = ppm∈product∗100ppm∈the feed
=0.2×100%
50
= 0.4%
Percentage of sulphur converted to H2 S = 100 - 0.4
=99.6%
Reacted sulphur in the reactor = 12.273 x 0.996
= 12.224 kg /day
Unreacted sulfur in the product = 12.273 x 0.004 kg/day
= 0.0491 kg/day
H2 + S H2S
Reacted Sulfur = 12.224 kg/day
Required Hydrogen = 12.224 x2
32
= 0.764 kg/Day
Unreacted Hydrogen in the product = 2.9 x 1000- 0.764
= 2899.236 kg/Day
H2S in the product Stream = 12.224×34
32
= 12.988 kg/Day
Outlet flow rates from the Hydrotreater
Hydrotreated naphtha (Naphtha + Unreacted Sulfur) 245.437 MT/Day Hydrogen 2.899 MT/Day Hydrogen sulfide 12.988 kg/Day
Amount of sulfur in the outlet stream is negligible. Therefore we assume naphtha feed rate to be the same
as the inlet.
Components Flow Rate(MT/Day)
Weight %
Hydrogen 2.9 100
Hydrotreater
Components Flow Rate (MT/Day)
%
Hydrotreated Naphtha 245.437 98.8271Hydrogen 2.899 1.16731Hydrogen sulfide 0.012988 0.00590Total 248.348988 100
Components Flow Rate (MT/Day)
%
Naphtha 245.45 100
Here, Total Material In = 248.35 MT/day Total Material Out = 248.349 MT/Day ≈ 248.35 MT/day
Therefore Material in = Material out
Material in to the Hydrotreater Material out from the Hydrotreater
Component Flow Rate
(MT/Day)
% Component Flow Rate
(MT/Day)
%
Naphtha+Sulfur 245.45 98.88323 (Naphtha + Unreacted
Sulfur)
245.437 98.8271
Hydrogen 2.9 1.11677 Hydrogen 2.899 1.16731
Hydrogen sulfide 0.012988 0.00590
Total 248.35 100 Total 248.35 100
Desulfurization
The natural gas or naphtha feed were heated to 285-400 º C and then passed through one or two bed of
ZnO in the form of tablets, spheres, or extrudates where the function of the catalyst depends on the
chemical reaction:
ZnO + H2S ZnS + H2O
Usually zinc oxide catalyst is used as a mixture of ZnO and alumina as a binder in addition to some filler.
In general 90 % wt of ZnO is quiet acceptable. On using naphtha as feed the hydrogen sulfide being
reduced to 0.02 ppm.
Inlet flow rates of the desulfurization reactor
Hydrogen 2.899 MT/Day
Naphtha 245.437MT/Day
Hydrogen Sulfide 12.988 kg/Day (52.3ppm)
Required ZnO 31.07 kg/day
Calculation for Outlet Flow Rates
The gas leaves the purification section with a sulfur content of <1ppm at essentially the same
temperature.
(Ullaman Vol.A13,page 326)
Here the feed purification system sulfur content in output stream is maintained at 0.02ppm
Percentage of hydrogen sulfide in the product = ppm∈product∗100ppm∈the feed
=0.02∗100 %
52.3
= 0.038%
Percentage of H2S desulfurized = (100 - 0.038) %= 99.962%
Desulfurized H2S in the reactor = 12.988 x 0.99962
= 12.983 kg/Day
H2S in the outlet stream = (12.988 -12.983) kg/Day
= 0.005 kg/day
Hydrogen and naphtha flows quantity remain constant throughout the desulfurization reactor. But large
amount of H2S desulfurized in the reactor bed.
Output flow of the desulfurization reactor
Hydrogen 2.899 MT/Day
Naphtha 245.437 MT/Day
Hydrogen sulfide 0.005 kg/day
ZnS 0.0372073MT/Day
Desulfurizer
Components Flow Rate(MT/Day)
%
H2O 0.00690444 0.0027
Hydrogen 2.899 1.16733
Naphtha 245.437 98.8299
Hydrogen sulfide 0.000005 0.00007
Total 245.3429094 100
Components Flow rate (MT/Day)
%
ZnO 0.03107 100
Components Flow rate (MT/Day)
%
ZnS 0.0372073 100
Components Flow rate (MT/Day)
%
(Naphtha+UnreactedSulfur) 245.437 98.8271
Hydrogen 2.899 1.16731
Hydrogen sulfide 0.012988 0.00590
Total 248.348988 100
Material in to the desulfurization reactor Material in to the desulfurization reactor
Material Flow Rate
(MT/Day)
% Material Flow Rate
(MT/Day)
%
(Naphtha +
Unreacted Sulfur)
245.437 98.8127 Hydrogen 2.899 1.1671
Hydrogen 2.899 1.1671 Naphtha 245.437 98.8127
Hydrogen sulfide 0.012988 0.00522 Hydrogen sulfide 0.000005 0.000002013
ZnO 0.03707 0.01498 ZnS 0.0372073 0.01498
H2O 0.00687 0.002766
Total 248.38608 100 Total 248.386058 100
General formula of naphtha = CnH2.2n
(Ullaman Vol.A13, page 326)
Mass of naphtha in feed = 245.437 MT/Day
Mole of carbon in naphtha feed = 12n
14.22n×
245.43712
= 17.2 x 103 kmol/day
Calculation for inlet Flow Rates
Steam
Steam is added to the inlet feed to give ratio of 3mole of steam per mole of carbon.
(Ullaman Vol.A13, page 326)
Therefore,
Steam (mol)catbon∈ feedstock naphtha (mol)
= 3
Steam mole flow rate = 17.2 x 103 x 3 kmol/day
= 51600 kmol/day
Steam flow rate = 928.8MT/day
Input Flow rates to the reformer
H2O 0.00687 MT/Day
Hydrogen 2.899 MT/Day
Naphtha 245.437 MT/Day
Steam 928.8MT/Day
Calculation for Outlet Flow Rates
Assume that naphtha entering to the reformer completely react with steam.
Required steam flow rate = 245.437×18nMT /day
n× (12+2.2 )
= 311.117 MT/Day
Similarly,
CO mass flow rate in the product = 483.96 MT/Day
H2 mass flow rate in product = 72.59 MT/Day
Assume that 0.1 fraction of CO in above reaction is converted into the CO2 and H2 presence of H2O.
CO + H2O CO2 + H2
CO contributes for the shift reaction = 483.96 x 0.1 MT/Day
= 48.396 MT/day
Required steam flow rate for shift reaction = 31.112 MT/Day
CO2 mass flow rate in product stream = 76.051 MT/day
Formed H2 in shift reaction = 3.457 MT/Day
CnH2.2n (Naphtha) + n H2O n CO + 2.1n H2
Naphtha = 0
Steam = 928.8 MT/Day - (311.117 MT/Day+31.112 MT/day) +0.0073 MT/Day
= 586.578 MT/Day
H2 =2.899 MT/Day + 72.59MT/Day + 3.457 MT/Day
= 78.946 MT/Day
CO = 483.96 MT/Day *0.9
= 435.564 MT/Day
CO2 = 76.051 MT/Day
Output Flow rates from the reformer
Naphtha 0
Steam 586.578 MT/Day
H2 78.946 MT/Day
CO 435.564 MT/Day
CO2 76.051 MT/Day
Input mass flow rate = 1177.133 MT/Day
Output mass flow rate = 1177.139 MT/day ≈ 1177.13 MT/Day
Component Flow Rate(MT/Day) %
Naphtha 0 0
Steam 586.578 49.83082
H2 78.946 6.76599
Reformer
Components Flow Rate
(MT/Day)
%
H2O 0.00687 0.00058362
Hydrogen 2.899 0.24627
Naphtha 245.437 20.85023
Steam 928.8 78.90292
Total 1177.13287 100
CO 435.564 37.00192
CO2 76.051 6.40127
Total 1177.13287 100
Material in to the Reformer Material out from the Reformer
Material Flow Rate
(MT/Day)
% Material Flow Rate
(MT/Day)
%
Steam 928.8 78.90292 CO 435.564 37.00192
Naphtha 245.437 20.85023 Steam 586.578 49.83082
Hydrogen 2.889 0.24627 Hydrogen 78.946 6.76599
H2O 0.00687 0.00058362 Carbon Dioxide 76.051 6.40127
Total in 1177.13287 100 Total out 1177.13287 100
High Temperature Shift Reactor (HTS Reactor)
Inlet flow rate to the HTS reactor
Steam 586.578 MT/Day
H2 78.946 MT/Day
CO 435.564 MT/Day
CO2 76.051 MT/day
From literature amount of CO remaining after conversion =7.9% (mole percentage)
Suppose x mol of CO is reacted
CO + H2O CO2 + H2
After the reaction quantities of the each components
nCO = 435.564∗106
28−x
nsteam = 586.578∗106
18−x
nH2 =78.946∗106
2+x
nCO2 = 76.051∗106
44+x
from the literature amount of CO remaining after the conversion is 7.9%
7.9 =
435.564∗10628
−x
435.564∗10628
−x+586.578∗106
18−x+
78.946∗1062
+x+76.051∗106
44+x
∗100
=435.564∗106
28−x
89344955.63∗100
X = 8497605.648mol
Therefore reacted CO mol = 8497605.648mol
Therefore output moles of each component at the outlet
nCO = 435.564∗106
28−8497605.648mol
= 7058251.495mol
nsteam = 586.578∗106
18−8497605.648mol
= 24090061.02mol
nH2 =78.946∗106
2+8497605.648mol
= 47970605.65mol
nCO2 = 76.051∗106
44+8497605.648mol
= 10226037.47mol
Outlet flow rates from the HTS reactor
CO 197.6310419MT/Day
Steam 433.6210984MT/Day
H2 95.9412113MT/Day
CO2 449.94565MT/Day
Component Mass Flow Rate
(MT/Day)
%
Steam 586.578 49.83082
H2 78.946 6.76599
CO 435.564 37.00192
CO2 76.051 6.40127
Total 1177.139 100
High Temperature Shift Reactor
Component Flow Rate
(MT/Day)
%
Steam 433.6210419 36.83686
H2 95.9412113 8.15037
CO 197.6310419 16.7891
CO2 449.94565 38.22367
Total 1177.139 100
Material in to the HTS Material out from the HTS
Material Flow Rate % Material Flow Rate %
CO 435.564 37.00192 CO 197.6310419 16.7891
Steam 586.578 49.83082 Steam 433.6210984 36.83686
Hydrogen 78.946 6.76599 Hydrogen 95.9412113 8.15037
Carbon Dioxide 76.051 6.40127 Carbon Dioxide 449.94565 38.22367
Total in 1177.139 100 Total out 1177.139 100
Low Temperature Shift Reactor (LTS Reactor)
Inlet flow rate to the LTS reactor
CO 197.6310419MT/Day
Steam 433.6210984MT/Day
H2 95.9412113MT/Day
CO2 449.94565MT/Day
It is assumed that CO remaining after conversion =0.4% (mole percentage)
Suppose x mol of CO reactes
CO + H2O CO2 + H2
After the reaction quantities of the each components
n CO = 197.6310413∗106
28− x
nsteam = 433.6210984∗106
18−x
nH2 =95.9412113∗106
2+x
nCO2 = 449.94565∗106
44+ x
0.4=
197.6310413∗10628
−x
197.6310413∗10628
−x+95.9412113∗106
2+x+
449.94565∗10644
+x∗100
X = 6770151.291mol
Therefore reacted CO mol = 6770151.291mol
Therefore output moles of each component at the outlet
nCO = 197.6310413∗106
28−6770151.291mol
= 288100.184mol
nsteam = 433.6210984∗106
18−6770151.291mol
= 17319909.73mol
nH2 =95.9412113∗106
2+6770151.291mol
= 54740756.94mol
nCO2 = 449.94565∗106
44+6770151.291mol
= 16996188.79mol
Outlet flow rates from the LTS reactor
CO 8.066805152MT/Day
Steam 311.7583751MT/Day
H2 109.4815139MT/Day
CO2 747.8323068MT/Day
Component Mass Flow Rate %
Component Mass Flow Rate
(MT/Day)
%
CO 8.066805152 0.685289
Steam 311.7583751 26.48441476
Hydrogen 109.4815139 9.30064452
Carbon Dioxide 747.8323068 63.52965171
Total out 1177.13900 100
(MT/Day)
CO 197.6310419 16.7891
Steam 433.6210984 36.83686
Hydrogen 95.9412113 8.15037
Carbon Dioxide 449.94565 38.22367
Total in 1177.139 100
Material in to the LTS Material out from the LTS
Material Flow Rate % Material Flow Rate %
CO 197.6310419 16.7891 CO 8.066805152 0.685289
Steam 433.6210984 36.83686 Steam 311.7583751 26.48441476
Hydrogen 95.9412113 8.15037 Hydrogen 109.4815139 9.30064452
Carbon Dioxide 449.94565 38.22367 Carbon Dioxide 747.8323068 63.52965171
Total in 1177.139 100 Total out 1177.13900 100
Condensate Drum
Output stream conditions of low temperature shift reactor.
Pressure ≈18bar
Temperature 212.77oC
Saturate steam temperature at 18bar = 205.9oC
Therefore effluent steam from LTS is at superheated region.
Take condensate collector operating temperature as 105oC and its pressure 17 bar
(Hydrogen from Steam-Methane Reforming with CO2 Capture, John C. Molburg and Richard D. Doctor, Page 12)
Saturated water temperature at 17bar 204.272oC
Tsaturate > condensate drum operating temperature
Therefore in condensate collecting vessel we can assume that all the steam which in product stream will
be condensed.
Inlet flow rate to the Condensate Drum
CO 10.01063504MT/Day
Steam 313.00798014MT/Day
H2 109.3426689MT/Day
CO2 744.7777172MT/Day
Outlet flow rate from the Condensate Drum
CO 10.01063504MT/Day
H2 109.3426689MT/Day
CO2 744.7777172MT/Day
Material accumulated in Condensate Drum
Condensate 313.00798014MT/Day
Material in to the Condensate Drum Material out from the Condensate Drum
Material Flow Rate Material Flow Rate
CO 8.066805152MT/Day CO 8.066805152MT/Day
Steam 311.7583751MT/Day Hydrogen 109.4815139MT/Day
Hydrogen 109.4815139MT/Day Carbon Dioxide 747.7777172MT/Day
Carbon Dioxide 747.8323068MT/Day Total out 865.3260363MT/Day
Total in 1177.139001MT/Day
Material accumulated in Condensate Drum
Material Flow Rate
Condensate 311.7583751MT/Day
Pressure Swing Adsorption
Inlet flow rate to the PSA
CO 8.066805152MT/Day
Hydrogen 109.4815139MT/Day
Carbon Dioxide 747.7777172MT/Day
Calculation for outlet flow stream from the PSA
It is assumed that 99.6% of purity for final product.
Ullaman Vol.A13, page 327
Total amount of CO and CO2 available in the product stream after PSA unit
99.6= 109.4815139
109.4815139+x100
X = 0.43968MT/Day
Removal efficiency of PSA = 755.8445224−0.43968
755.8445224∗100
= 99.9418%
Outlet flow rate from the PSA
Hydrogen 109.4815139MT/Day
CO + Carbon Dioxide 0.43968MT/Day
Material in to the PSA unit Material out from the PSA unit
Material Flow Rate Material Flow Rate
CO 8.066805152MT/Day CO + CO2 0.43968MT/Day
Carbon Dioxide 747.8323068MT/Day Hydrogen 109.4815139MT/Day
Hydrogen 109.4815139MT/Day Total out 109.9211939MT/Day
Total in 865.3806259MT/Day
Material accumulated in PSA unit
Material Flow Rate
CO and CO2 755.4048424MT/Day
