ECONOMICS

EXPANSION FOR

THE Ya. and

OF

THE

RAW MATERIAL

PETROCHEMICAL S. A m i r o v , D. Y a . V. E . T i s h c h e n k o

BASE

INDUSTRY Rusanovich,

UDC 665.6: 54.002.2

The development and expansion of the p e t r o c h e m i c a l industry in r e c e n t y e a r s have been c h a r a c t e r i z e d by a concentration of production and an i n c r e a s e in the size of individual p r o c e s s units and p r o c e s s sections, the following figures being typical (in thousand m e t r i c tons per y e a r ) : ethylene production 300-450; butyl alcohols 60; butadiene 100-120; isoprene 60-90. Along with the use of l a r g e r p r o c e s s units has come an i m p r o v e m e n t in the production economics, with m o r e favorable conditions for the combined utilization of raw m a t e r i a l r e s o u r c e s , including byproducts and wastes. At the same time, the concentration of p e t r o c h e m i c a l production has led to p r o b l e m s in r a w m a t e r i a l supplies. For example, in o r d e r to operate USSR ethylene production units of the l~P-300 and I~P-450 types, 1.5-2 million m e t r i c tons per y e a r of s t r a i g h t - r u n naphtha cuts a r e r e q u i r e d . It is difficult to produce such amounts of naphtha for pyrolysis (cracking) within the ranks of the existing fuelprofile r e f i n e r i e s . Only the l a r g e s t p e t r o l e u m r e f i n e r i e s can s e r v e as a stable s o u r c e of feedstock. However, the lack of any such r e f i n e r i e s in many d i s t r i c t s has created a need for setting up an autonomous raw m a t e r i a l base equipped with specialized production units of the AT-6 type, or r e f i n e r i e s for p r i m a r y crude oil p r o c e s s ing with the specific purpose of producing p e t r o c h e m i c a l feedstocks. In the foreign l i t e r a t u r e [1-3], we find a r a t h e r large number of communications r e g a r d i n g the future p r o s p e c t s for fuel-profile r e f i n e r i e s manufacturing motor fuels and p e t r o c h e m i c a l feedstocks, and also c h e m i c a l - p r o f i l e r e f i n e r i e s that specialize in the production of m o n o m e r s . The basic difference in the flow plan for a c h e m i c a l - p r o f i l e r e f i n e r y in c o m p a r i s o n with the generally known or c l a s s i c a l flow plans is that in the c h e m i c a l - p r o f i l e r e f i n e r y the naphtha cuts are subjected to p y r o l y s i s (cracking), with the exception of the C6-C s h y d r o c a r b o n s , which a r e directed to catalytic r e f o r m i n g for aromatization. Also directed to p y r o l y s i s a r e the middle distillates, i.e., the k e r o s i n e s and gas oils. H e r e the end products a r e ethylene, propylene, butylene, butadiene, a r o m a t i c hydrocarbons (benzene, toluene, xYlenes), coke, and LPG. These questions of combination p r o c e s s i n g of crude oils in o r d e r to expand the raw material base of the chemical industry have also been examined in USSR studies. In the work of INKhS AN SSSR [institute of P e t r o chemical Synthesis, Academy of Sciences of the USSR] [4, 5], analyses have been made of petrochemical complexes with various flow plans for the p y r o l y s i s of liquid p e t r o l e u m feedstocks, secondary petroleum refining p r o c e s s e s , and naphtha and diesel fuel upgrading p r o c e s s e s . When p r o c e s s i n g crude oil in accordance with a flow plan providing for the output of about 45% light p e t r o l e u m products and 14% p e t r o c h e m i c a l products (Variant I}, considerable reductions a r e achieved in the p r o r a t e d costs, * amounting to 30% for naphtha production, 10% for ethylene and propylene production, and 6% for acetylene production; these figures all r e f e r to the costs in a typical section in a fuel-profile r e f i n e r y . When the output of p e t r o c h e m i c a l products in the r e f i n e r y is i n c r e a s e d to 24 and 34% (Variants II and IIl), the production efficiency on the whole is i n c r e a s e d ; we find i n c r e a s e s in the profit, turnover r a t i o , and profitability (Table 1). In c e r t a i n economic d i s t r i c t s , it is of p r a c t i c a l i n t e r e s t to set up p e t r o c h e m i c a l complexes with a combination of traditional crude oil p r o c e s s i n g (catalytic cracking, coking, hydrocracking, hydrotreating, etc.) with the simultaneous output of engine fuels and m o n o m e r s for p e t r o c h e m i c a l production. This will provide considerable savings in capital and operating costs. However, the trend toward setting up such complexes is c u r r e n t l y limited by the slight reduction in yield of light p e t r o l e u m products when the production of p e t r o chemical products is i n c r e a s e d . In this connection, in d i s t r i c t s with a high consumption of engine fuels, it is advisable to set up r e f i n e r i e s with total and combined p r o c e s s i n g of r e f i n e r y hydrocarbon gases and the p r o duction of feedstocks for the chemical industry. It is n e c e s s a r y to bring into chemical p r o c e s s i n g not only the C3-C 4 h y d r o c a r b o n s , but also the C2, with segregation and utilization of e t h a n e - e t h y l e n e and hydrogen fractions. *The Russian t e r m translated as p r o r a t e d costs (privedennye zatraty) r e f e r s to the operating costs plus a standardized percentage of the capital costs - Translator. Ufa P e t r o l e u m Institute (UNI). Translated f r o m Khimiya i Tekhnologiya Topliv i Masel, No. 6, pp. 49-52, June, i979. 0009-3092/79/0506-0447507.50

9 1980 Plenum Publishing Corporation

447

TABLE 1. Economic Indices of P e t r o l e u m P r o c e s s i n g In Refineries with P e t r o c h e m i cal and Fuel P r o f i l e s [2, 3l Variant Typical section of, In~e~ I n IlI fnel-ptofile refin. Nominal crude oil capacity, thousand tons/yr

G~ss product output, Prorated costs per tonof product, % automotive gasoline efl~ylene, propylene acetylene Profit, ~ .. , Turnover, ruble.s/ru~te Profitability, qo Payout period of capital investment, yr

;000 ;O00 ~000

6000

217

100

118

169

66

,2 0,~ 0,86720,9279 94 232 1.7

73 345

1,4

1,3

100 1oo 1o0

10o

0,54 93

4,5

*The R u s s i a n ter#n t r a n s l a t e d as t u r n o v e r r a t i o (fondootdacha) r e f e r s to the r a t i o of annual production volume to the production capital (usually both fixed a s s e t s and w o r k ing capital) - T r a n s l a t o r . The c o m p l e x and r a t i o n a l utilization of r e f i n e r y h y d r o c a r b o n g a s e s m a y a p p e a r at the p r e s e n t t i m e in m a n y v e r s i o n s ; t h e s e gases m a y be p r o c e s s e d either toward fuel end products or c h e m i c a l end products. The competition between these two directions d e t e r m i n e s the c u r r e n t situation in production and utilization of light h y d r o c a r b o n feedstocks in p e t r o c h e m i c a l production. The p r o b l e m is complicated by the fact that t h e r e a r e m a n y p a r t i a l l y or c o m p l e t e l y interchangeable types of h y d r o c a r b o n feedstocks for the production of both p e t r o chemicals and gasoline components. For e x a m p l e , alkylate is produced m a i n l y f r o m butylenes, and also f r o m propylene. However, in the production of c o m m e r c i a l gasolines, the alkylate m a y be p a r t i a l l y r e p l a c e d by butane, isopentane, i s o m e r i z e d light h y d r o c a r b o n s , or i s o m e r i z e d naphtha. The propylene and butylenes, which a r e r e c o v e r e d f r o m r e f i n e r y h y d r o c a r b o n g a s e s , m a y be directed to the synthesis of m a n y different kinds of p e t r o c h e m i c a l p r o d u c t s . In view of this g r e a t d i v e r s i t y in production methods for the s a m e p r o d u c t s f r o m different r a w m a t e r i a l s , traditional methods cannot be used to d e t e r m i n e the optimal directions for propylene and butylene utilization. M o r e o v e r , the rigid quality r e q u i r e m e n t s and heavy demand for automotive gasolines that a r e imposed by the t r a n s p o r t industry a r e r e s p o n s i b l e for a l a r g e demand for high-octane blending components. The c u r r e n t GOST s t a n d a r d s for c o m m e r c i a l g a s o l i n e s , which i m p o s e limits on the v a p o r p r e s s u r e , distillation c u r v e , and content of a r o m a t i c h y d r o c a r b o n s , r e s t r i c t the use of s o m e components. For example, the m a x i m u m butane content in gasolines is 4.5-5.5?0, as limited by the allowable v a p o r p r e s s u r e . The content of a r o m a t i c h y d r o c a r b o n s m u s t be no g r e a t e r than 40-45%, since higher contents a g g r a v a t e p r o b l e m s with combustion c h a m b e r deposits. Because of t h e s e v a r i o u s r e q u i r e m e n t s , c o m m e r c i a l automotive gasolines a r e produced by combining m a n y different components in v a r i o u s ways. The optimal r a t i o of these components c a n be d e t e r m i n e d by linear p r o g r a m m i n g techniques. In the following p a r a g r a p h s we p r e s e n t the solution of an C a h y d r o c a r b o n s for the production of p e t r o c h e m i c a l s , so as to a p p r o p r i a t e quality c h a r a c t e r i s t i c s of the automotive gasolines [6, 7]. The m a t h e m a t i c a l f o r m a l i z a t i o n of the p r o b l e m has the

rn

448

optimization p r o b l e m in the utilization of C a and m a x i m i z e the profit while p r e s e r v I n g the and the r e q u i r e d gasoline production volume following f o r m :

TABLE 2. Results from Solution of Optimization Problem in Utilization of C 3 and C4 Unsaturated Hydrocarbons [6] Production, thousand tons

Products

II

From propylene Phenol and acetone Butyl alcohols Acrylonitrile Polypropylene (from pyrolysis propylene) C7 alkyI~te From butanebutylene cut Isoprene Butadiene Methyl ethyl ketone Polyisobutylene Cs alkylate From pyrolysis butadmne cut Isopreae Butadiene (extraction) Butadiene (dehydrogenation of n-butylenes) Butyl rubber From isobutane Isoprene

96/'60*

60[37,5* 30

III"

l-~

25

60

92

140

140

41,3 49,4

92

13,5 9,64 95,6

-

-

42,6 -

-

27.5 -

-

18,7

74,4

2,6,9 42,6 16,6 -

-

35

*First figure indicates phenol, second figure acetone. t/~

F

X~ ~ o; Xtt ~ o

w h e r e ~ i s the n u m b e r o f u n i t s in the j - t h m a n u f a c t u r i n g p r o c e s s ;

(5)

Xij is the q u a n t i t y of the i - t h c o m p o n e n t

required for optimal loading of the j-th manufacturing process; n is the number of processes that use the i-th component as feedstock; m is the number of types of feedstock that are taken into account in calculating the material balances; r is the number of types of commercial products (gasolines and petrochemical products) ; Qi is the resources of the i-th component; Xi/ is the quantity of the i-th component involved in the l-th commercial product; ]3/ is the planned production volume for the l-th commercial product; fiRi is the R-th quality characteristic of the i-th component; fil~ is the R-th quality characteristic of the/-th commercial product (in accordance with the GOST standard) ; Hi/ is the profit pertaining to one ton of th~ i-th component involved in the /-th commercial product. The problem has been solved for an arbitrarily defined fuel-profile refinery that includes units with the following capacities (thousand tons/yr) : two atmospheric-vacuum pipestill units, 6000 each; two catalytic cracking units, 1370 each; one catalytic reforming unit, 1200; two fluid coking units, 1800 each; two isomerization units, 68 each; two alkylation units, 68.34 each. These units are responsible for the output of the major quantity of gasoline components and gases used in the production of propane-propylene, butane-butylene, butane, and isobutane cuts, which may be ultimately incorporated in gasolines either through alkylato or by direct blending (other than the unsaturated hydrocarbons, which can be brought into gasolines only through alkylate or polymer distillate). This problem has been solved in three variants. First variant - gasoline production brought up to the required volume; the C3 and C4 hydrocarbons are used in the production of petrochemicals in typical units. Second variant - gasoline and petrochemical output limited by use of standard-capacity units, with C3 and C4 hydrocarbons directed to a pyrolysis (cracking) unit; this variant applies to refineries in which an ]~P-300 unit is included. Third variant - same as the second, but without tying in or limiting the petrochemical production volume to that of standard-capacity units.

449

TABLE 3. Data on Output and Ratio of Gasoline Grades output and ratio of grades, % I

[

II

In

I

Output of commercial gasolines total AI-98, leaded AI-93, leaded AI-93, unleaded Ratio of grades of commercial gAi asolines -98, leaded AI-93, leaded AI-93, unleaded

[ 100,01 89,7 100,01 136,1 100,0 ] 100,0 100,0| 49,3 l

87,0 108,3 100,0 40,8

11,61 17,6 14,9 59:811 66,7 71,2 15,7 13,9

The r e s u l t s f r o m solution of the p r o b l e m s (Tables 2 and 3) show that the p r o c e s s i n g of C 3 and C 4 u n s a t urated h y d r o c a r b o n s into p e t r o c h e m i c a l products can be achieved with e s s e n t i a l l y no loss in output of autom o t i v e gasolines. In the f i r s t v a r i a n t , with a fixed gasoline production volume, this can be done only by r e p l a c i n g the butylene alkylate by propylene alkylate. Then, f r o m the b u t a n e - b u t y l e n e cut, 92,000 tons of butadiene and 60,000 tons of i s o p r e n e can be obtained. In the second v a r i a n t , t h e r e is a m a r k e d expansion in the p e t r o c h e m i c a l p r o d u c t mix that can be obtained in typical (standard) units. In the third v a r i a n t , l a r g e scale production can b e organized for butyl alcohols (about 110,000 tons), polypropylene (140,000 tons), butadiene ( m o r e than 150,000 tons), i s o p r e n e (60,000 tons), and polyisobutylene (74,400 tons). If n e c e s s a r y , the production of polyisobutylene can be r e s t r i c t e d quite c o n s i d e r a b l y so as to s e t up i s o p r e n e production with a capacity of m o r e than 90,000 tons (without dehydrogenation of isobutane), or m o r e than 130,000 tons (with dehydrogenation). In the second and third v a r i a n t s , the production of p e t r o c h e m i c a l s based on r e f i n e r y and p y r o l y s i s - b y p r o d u c t C 3 and C 4 h y d r o c a r b o n s is p o s s i b l e with a c e r t a i n reduction in output of automotive gasolines. In all t h r e e v a r i a n t s , since none of t h e m absolutely r e q u i r e s complete utilization of all gasoline c o m ponents, c e r t a i n e x c e s s e s or r e s i d u e s of these components a r e obtained, mainly catalytically c r a c k e d naphtha. It is obvious that, in o r d e r to i n c r e a s e the h y d r o c a r b o n r e s o u r c e s , both catalytic c r a c k i n g units should be changed o v e r to h i g h - t e m p e r a t u r e o p e r a t i n g conditions in o r d e r to r e d u c e the naphtha yield and i n c r e a s e the naphtha octane n u m b e r . When m o r e s e v e r e catalytic c r a c k i n g conditions a r e used, the output of p e t r o c h e m i c a l s can be i n c r e a s e d quite significantly. The efficiency of utilization of propylene and butylenes for this p u r p o s e is quite e v i d e n t ; the profits for the different v a r i a n t s a r e r e s p e c t i v e l y 154, 222.3, and 275.7 million rubies (Table 4). TABLE 4. Results f r o m Calculation of Profit Profit, million rubles from petro- t from Variant total chemical gasolines " products First

Se.eond Third

153,99

222,22 275,72

l

64,24 55,81 53,85

89,75 166,41 221,87

TABLE 5. Data on Output and Ratio of G a s o line Grades for Ufa Industrial Complex ]Output and ratio of fades (in~o) for variant, optimal

baseline Output of commercial gasolines total AI-.98, leaded

AI-93, leaded AI-93, unleaded Ratio of commercial gasoline

~ades tal AI-98, leaded AI-93, leaded AI-93, unleaded

450

100,0 100,0

100,0 100,0

9

106,3 101,0 102,2 102,8

100,0 12,1

I00,0

23,2

28,6

64,7

11,6

59,8

The solution of an analogous p r o b l e m in optimization of C 3 and C 4 hydrocarbon utilization for l a r g e c o m m e r c i a l c o m p l e x e s (using the Ufa group of r e f i n e r i e s as an example) has shown that, in this c a s e also, the r e s o u r c e s of p r o p a n e - p r o p y l e n e and b u t a n e - b u t y l e n e cuts can be t r a n s f e r r e d to p e t r o c h e m i c a l production without any loss in output of automotive gasolines. The output of high-octane c o m m e r c i a l gasolines can be a c c o m p l i s h e d through utilization of components f r o m catalytic c r a c k i n g and r e f o r m i n g , and also by a m o r e extensive use of i s o m e r i z e d naphthas, i s o m e r i z e d light h y d r o c a r b o n s , and n a t u r a l gasoline. The joint p r o c e s s i n g of C3-C 4 r e f i n e r y h y d r o c a r b o n s and the b u t y l e n e - b u t a d i e n e cut f r o m p y r o l y s i s can give a c o n s i d e r a b l e i n c r e a s e in the output of p e t r o c h e m i c a l s , amounting to no less than 50,000 tons of butadiene, 30,000-35,000 tons of i s o p r e n e , 44,000 tons of butyl r u b b e r , 250,000 tons of phenol, and 30,000-40,000 tons each of butyl alcohols and polypropylene. The output and r a t i o of c o m m e r c i a l gasolines for the Ufa industrial complex a r e shown in Table 5; the r e s p e c t i v e profits for the two v a r i a n t s a r e 150 and 220 million r u b l e s . Thus, t h e s e calculations and solutions of the optimization p r o b l e m in gasoline production have d e m o n s t r a t e d the f e a s i b i l i t y in p r i n c i p l e and the economic advantages in using p e t r o l e u m r e f i n e r y h y d r o c a r b o n g a s e s in c h e m i c a l p r o c e s s i n g . LITERATURE 1.

2. 3. 4. 5. 6.

7.

CITED

Econ. Eng. Rev., 3, No. 1, 22 (1971). H y d r o c a r b o n P r o c e s s . , 49, No. 2, 67 (1970); 51, No. 3, 73 (1972). Erdoel Kohle, No. 6, 244 (1976). A. L. Rabkina et al., Khim. Tekhnol. Topl. Masel, No. 6, 23 (1977). P. A. B o r i s o v et al., in: Questions of E c o n o m i c s in the P e t r o c h e m i c a l Industry [in Russian], INKhS Akad. Nauk SSSR, Moscow (1977), p. 55. D. A. Rusanovich et al., S u m m a r i e s of P a p e r s f r o m All-Union S y m p o s i u m of Young Scientists and Specialists, held in Minsk on M a r c h 29-30, 1972 [in Russian], NIIT]~khim, Moscow (1972), p. 58. Ya. S. A m i r o v et al., in: Interuz Collection: Economic Efficiency of the P e t r o l e u m Refining and P e t r o c h e m i c a l Industry [in Russian], UNI, Ufa (1977), p. 149.

ECONOMIC

EFFICIENCY

FRACTION

AS

OF

PYROLYSIS

G. M. Kaviev, E. and O. D. Lukshina

UTILIZATION

OF

E T H A NE

FEEDSTOCK A.

Silkin,

UDC 547.212: 665.642.3.65.018.2

Ethylene production units r e p r e s e n t the l a r g e s t c o n s u m e r of h y d r o c a r b o n feedstocks. Hence, selection of the m o s t e c o n o m i c a l type of p y r o l y s i s feedstock is a m a j o r factor in d e t e r m i n i n g the efficiency of the p e t r o c h e m i c a l and c h e m i c a l i n d u s t r i e s . Ethylene production m u s t be i n c r e a s e d through introduction of ]~P-300 and 1~P-450 units, and by the u s e of naphtha and k e r o s i n e - g a s o i l cuts as feedstocks. Orientation of the r a w m a t e r i a l b a s e for ethylene production toward liquid feedstocks is traditionally explained by the need for furnishing these l a r g e - s c a l e units with a stable and u n i f o r m feedstock. The r e s o u r c e s of other types of f e e d s t o c k s such as ethane or LPG at any given location a r e usually inadequate to supply l a r g e s c a l e ethylene units; exceptions a r e found in such d i s t r i c t s as the Tatar ASSR, Orenburg, and the Ukrainian SSR. Another advantage of liquid f e e d s t o c k s for p y r o l y s i s is the fact that such feedstocks yield not only ethylene and p r o p y l e n e , which a r e m o n o m e r s for p e t r o c h e m i c a l s y n t h e s i s , but also a b u t y l e n e - b u t a d i e n e cut (BBC), ~hich is a r a w m a t e r i a l for synthetic r u b b e r m o n o m e r s , and benzene, which is the s t a r t i n g m a t e r i a l for a n u m b e r of c h e m i c a l s y n t h e s e s . The s h o r t a g e s in these types of products a r e often the decisive factor in selecting the type of p y r o l y s i s feedstock to be used. However, planning for the u s e of liquid cuts f r o m the r e f i n e r y as the r a w m a t e r i a l b a s e in ethylene p r o duction does have c e r t a i n negative consequences, in connection with the limitations on these r e s o u r c e s . The p r i m a r y d i v e r s i o n of naphtha cuts for p e t r o c h e m i c a l p u r p o s e s will r e q u i r e m o r e s e v e r e c r u d e oil p r o c e s s i n g All-Union S c i e n t i f i c - R e s e a r c h Institute of H y d r o c a r b o n Feedstocks (VNIIUS). T r a n s l a t e d f r o m Khimiya i Tekhnologiya Topliv i Masel, No. 6, pp. 53-55, June, 1979.

0009-3092/79/0506-0451507.50

9 1980 Plenum Publishing C o r p o r a t i o n

451