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Файл:Chemical Engineering of Natural Fuels and Carbon Materials. Study Guide
.pdf
Q
= GF · q = 268176 · 590 = 158223.8 MJ/h,
reac
where q is the thermal effect of endothermic reactions of catalytic cracking
(Appendix 5).
Q
= 0,05 · Q
losses
= 0.05 · (172555.45 +0.7407 · G
in
cir.cat.
) =
= 8627.77 +0.037 · G
cir.cat.
, MJ/h.
Q
= 645266.05 + 0.555· G
out
cir.cat.
.
By using the equation (9.6), the amount of circulating catalyst can be
calculated:
G
= 3236976.26 kg/h.
cir.cat
The circulation multiplicity of the catalyst can be found by the
formula:
Task 9.4
Calculate the heat balance of the catalytic cracking reactor and the
circulation multiplicity of the catalyst.
The feedstock in the unit is hydrotreated vacuum gas oil with the
temperature boiling range 350 – 550 ° C, density 0.910. The pressure in the
reactor is 180 kPa. The temperature of feedstock is 270 °C. Along with
feedstock, 4100 kg/h of superheated steam with the temperature of 350 °C is
introduced into the reactor. An additional amount of steam for stripping the
catalyst (for the circulated catalyst) is 0.5% wt.
The specific heat of the catalyst equals 1.1 kJ / kg ∙°C, the specific
heat of coke is 2.0 kJ / kg ∙°C. Temperatures in the reactor zones are the
following: t1 = 520 °C, t2 = 510 °C, t3 = 490 °C. The regenerated catalyst
temperature is 680 °C. The average molecular weight of the products Ma. =
133 kg/kmol, the molecular weight of the dry gas is 32 kg/kmol. The
enthalpy of the acid gas at 490 °C is 1790.2 kJ / kg. Heat loss is 5% of the
total heat introduced into the reaction zone.
The material balance of the unit is given in table 9.2.
61
Table 9.2 – Material balance of the CC unit
Material stream
Specific
gravity
% wt.
kg/h
Income:
1. Vacuum gas oil (F)
2. Recycled product (R)
3. Steam
0,910
1.090
-
100.00
3.5
?
313000
10955
2971+?
In total:
326926+?
Outcome:
1. Dry gas
2.Н 2 S
3. Propane-propylene fraction
4. Butane - butylene fraction
5. Gasoline
6.Light gas oil
7.Heavy gas oil
8. Coke
9. Recycled product
10. Losses
11. Steam
0.738
0.973
1.090
-
1.090
-
2.45
0.2
5.84
10.25
54.52
20.14
0.3
4.3
3.5
2.0
?
7668.5
626
18279.2
32082.5
170647.6
63038.2
939
13459
6260
10955
2971+?
In total:
326926+?
9.2 Material balance calculation of steam cracking
Example 9.3
Calculate the material and trade balance of the ethane fraction steam
cracking unit with the annual output of 150000 tons of ethylene per year.
Annual working time fund is 344 days. The actual degree of conversion of
ethane is 60 % mol. The theoretical total degree of conversion of ethane is
65.334 % mol. The weight ratio of feedstock and water vapour is 1.0 :
0.3. The loss of ethylene in the process is 5 % by weight. The feedstock has
the following composition in % by weight: methane – 1.35; ethylene – 0.16;
ethane – 96.17; propylene – 0.25; propane – 2.07.
Solution:
Unit capacity for 100% ethylene is:
62
Component
М
% wt.
kg/h
kmol/h
СН
4
16
1.35
479.4
29.96
С2Н
4
28
0.16
56.82
2.03
С2Н
6
30
96.17
34151.5
1138.38
С3Н
6
42
0.25
88.78
2.11
С3Н
8
44
2.07
735
16.7
In total
100.00
35511.5
1189.18
(150000 ∙ 1000) / 8256 = 18168.605 kg/h.
Taking into account the loss of ethylene, the unit capacity is:
18168.605 ∙100 / 95 = 19124.847 kg/h or
19124.847 / 28 = 683.03 kmol/h.
Consumption of ethane fraction with the conversion of 60% mol.:
683.03 /0,6 = 1138.38 кmol/h or 1138.38∙30 = 34151.5 kg/h.
The total consumption of ethane fraction based on the content of
ethane in feedstock is:
34151.5 ∙100 / 96.17 =35511.5 kg/h.
The results of calculation of the feedstock component composition
is given in the table 9.3.
Table 9.3– Feedstock component composition
kmol/h of ethylene and the same amount of hydrogen is formed:
1. С
683,03 ↔ 683,03 683,03
1. The conversion of ethane in the process is the following.
The main reaction of the steam cracking process, in which 683.03
2Н6
↔ С2Н
+ Н2
4
The total amount of converted ethane is:
63
Reactions
Propane
comsumption in
% wt. of its initial
content in the
feedstock
Propane
comsumption
in kmol/h
1
2
3
5.01 5.01 5.01
4. С
3Н8
↔ С
3Н6
+ Н2,
30 %
5.01
1.67 0.835 0.835 0.835
5. 2С
3Н8
↔ С4Н
10
+ С
2Н4
+ Н2,
10 %
1.67
1.002 0.502 1.002
6. 2С
3Н8
↔ С
4Н8
+ 2СН4,
6 %
1.002
1138.38 ∙ 0,6533 = 743.75 kmol/h.
Consequently, the consumption of ethane in side reactions is:
743.75 – 683.03 = 60.72 kmol/h.
Adverse reactions of ethane conversion (ethane is consumed in
equal amounts):
2. 2С
2Н6
↔ С3Н
30.36 ↔ 15.18 15.18 15.18
3. С
+ Н2 ↔ 2СН4
2Н6
30.36 30.36 ↔ 60.72
2. The conversion of propane in the process is the following.
The conversion of propane in steam cracking process is presented in
table 9.4.
Table 9.4 - The conversion of propane
+ СН4 + Н2
6
64
Ending of table 9.4
1
2
3
3.34 1.67 3.34 1.67
7. 2С
3Н8
↔ С
4Н6
+ 2СН4 + Н2,
20 %
3.34
1.336 0.668 0.668 0.668
8. 2С
3Н8
↔ С
5Н10
+ СН4 + Н2,
8 %
1.336
2.505 5.01 7.515
9. С
3Н8
+ 2Н2 ↔ 3СН4,
15 %
2.505
3. The conversion of butadiene in the process:
0.475 0.475 0.475
10. С
2Н4
↔ С
+ Н2,
2Н2
In the reaction (10) 50% of ethylene formed in the reaction (5) is
consumed.
3. The conversion of butadiene in the process:
0.167 0.167 0.167 0.334
11. С
4Н6
+ С
2Н4
↔ С
+ 2Н2
6Н6
In the reaction (11) 10% of butadiene formed in the reaction (7) is
consumed.
5. The conversion of methane in the process:
1.18 1.18 1.18 3.54
12. СН4 + Н2О ↔ СО +3Н2
In the reaction (12) 1% of total amount of methane in pyrogas is
consumed:
n (СН4) = 29.96+15.18+60.72+1.002+3.34+0.668+7.515=118.385 kmol/h.
65
The amounts of all the components after the completion of all
Composition of
pyrogas
kmol/h
kg/h
Н
2
675.372
1350.744
СН
4
117.205
1875.28
С2Н
4
685.31
19188.68
С2Н
6
394.63
11838.9
С3Н
8
1.837
80.828
С4Н
10
0.835
48.43
С3Н
6
22.3
936.6
С4Н
6
1.503
81.162
С2Н
2
0.4175
10.855
С4Н
8
0.501
28.056
С5Н
10
0.668
46.76
С6Н
6
0.167
13.026
Н
2
О
590.674
10632.21
СО
1.18
33.04
Итог
2266.3
46164.95
Income
t/year
% wt.
Outcome
t/year
Output on
feedstock
% wt.
1 2 3 4 5
6
Ethane
fraction
Steam
293182.94
87954.88
100
30
1. Pyrogas,
including
ethylene
2. Losses
372716.08
150000.00
8421.74
127
51
3
In total
381137.82
130
In total
381137.82
130
reactions are presented in table 9.5 of the unit material balance. The trade
balance of the unit is presented in table 9.6.
Table 9.5 – Composition of pyrogas
Table 9.6– The trade balance of ethane fraction steam cracking process
66
Task 9.4
Calculate the material and trade balance of the ethane fraction steam
cracking unit with annual output of 135000 tons of ethylene per year.
Annual working time fund is 302 days. The actual degree of conversion of
ethane is 60% mol. Theoretical total degree of conversion of ethane is
65.33% mol. The weight ratio between feedstock and water vapor is 0.4
: 1.0. The loss of ethylene in the process is 5% by weight. The feedstock has
the following composition in % by weight: methane – 1.50; ethylene – 0.25;
ethane – 97.00; propylene – 0.25; propane – 1.00.
67
VOCABULARY BANK
INTRODUCTION
Oil refinery
Нефтепереработка
(нефтеперерабатывающий завод)
Petroleum naphtha
Нафта (соответствует пределам
выкипания бензиновой фракции)
Gasoline (petrol)
Бензин
Diesel fuel
Дизельное топливо
Asphalt (bitumen)
Битум
Heating oil
Мазут, печное топливо, топочный
мазут
Kerosene
Керосиновая фракция
Liquefied petroleum gas (LPG)
Сжиженные углеводородные газы
(СУГ)
Paraffins (alkanes)
Парафины (алканы)
Aromatics (arenes)
Ароматические углеводороды
(арены)
Naphthenes (cycloalkanes)
Нафтены (циклоалканы)
Olefins (alkenes)
Олефины (алкены)
Dienes
Диены
Alkynes
Алкины
Crude oil
Сырая нефть
Fuels
Топлива
Lubricants
Смазочные материалы
Feedstocks
Сырье
Alkylation
Алкилирование
Octane rating
Октановое число
Catalytic reforming
Каталитический риформинг
Hydrocarbons
Углеводороды
Catalytic cracking
Каталитический крекинг
68
Thermal cracking
Термический крекинг
Hydrocracking
Гидрокрекинг
Light distillates
Легкие дистилляты
Middle distillates
Средние дистилляты
Jet aircraft fuels
Авиационные топлива
Heavy distillates and residues
Тяжелые дистилляты и остатки
Tar
Гудрон
Petroleum coke
Нефтяной кокс
Steam-cracking
Пиролиз
Ethylene plant
Установка производства этилена
(установка пиролиза)
Desalter unit
Обессоливающая установка
Crude oil distillation unit (CDU)
Установка перегонки нефти
Atmospheric Distillation
Unit (ADU)
Установка атмосферной
перегонки нефти (АТ)
Vacuum distillation unit (VDU)
Установка вакуумной перегонки
нефти (ВТ)
Residual bottom
Остаточный кубовый продукт
перегонки
Hydrotreater unit
Установка гидроочистки
Reformate
Риформат (целевой продукт
каталитического риформинга)
Cyclic hydrocarbons
Циклические углеводороды
Byproduct
Побочный продукт
Desulfurize
Обессеривать
Fluid Catalytic Cracker (FCC) unit
Установка каталитического
крекинга "флюид"
(с псевдоожиженным слоем)
Visbreaking unit
Установка висбрекинга
Heavy residues
Тяжелые остатки
Viscosity
Вязкость
Merox unit
Мерокс процесс очистки газов
Mercaptans
Меркаптаны
69
Disulfides
Дисульфиды
Coking units (delayed coking, fluid
coker, and flexicoker)
Установки коксования
(замедленное коксование,
коксование-"флюид",
флексикокинг)
Sulfuric acid
Серная кислота
Hydrofluoric acid
Фтористоводородная кислота
High-octane components
Высокооктановые компоненты
Isomerization unit
Установка изомеризации
Linear molecules
Линейные молекулы
Branched molecules
Разветвленные молекулы
Steam reforming unit
Установка производства водорода
паровой конверсией
Amine gas treater
Установка аминовой очистки газа
(с использованием в качестве
абсорбентов растворов аминов)
Claus unit
Установка Клауса (производства
серы)
"Tail" gas treatment
Очистка "хвостовых" газов
HT – Hydrotreating
Гидроочистка (ГО)
HPU – Hydrogen Production Unit
Установка производства водорода
Vacuum gas oil
Вакуумный газойль
SRU – Sulfur Recovery Unit
Установка производства серы
Process flow diagram
Технологическая схема процесса
Solvent refining
Сольвентные методы переработки
углеводородного сырья
(с использованием растворителей)
Solvent dewaxing units
Установки депарафинизации с
использованием растворителей
Steam
Пар
Storage tanks
Резервуары для хранения
Intermediate products
Промежуточные продукты
End products
Конечные продукты
70
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