SU1174421A1 - Method of controlling two-step reactor of dehydrogenating hydrocarbon raw material - Google Patents

Abstract

METHOD OF MANAGING THE TWO-STEPPED REACTOR. Dehydrating Hydrocarbon Raw Materials by adjusting the composition of the contact gas after the first and second stages of the reactor by varying the temperature of the reaction mixture at the inlet of the corresponding stage of the reactor depending on the flow of raw materials into the reactor and the composition of the gas at the entrance of the corresponding stage of the reactor, controlling the consumption of fresh raw materials and steam differs from; and in order to reduce the consumption of raw materials and energy consumption, they regulate the ratio of the consumption of fresh raw materials and steam by changing the flow rate of the pair, and the consumption of fresh raw materials and the composition of the contact gas after the first and second stages of the reactor are adjusted depending on the consumption of fuel gas in the furnace , the amount of energy I at the stages of dehydrogenation and separation, the amount of by-product (L and target products and losses of the target product.

Description

This invention relates to the automation of industrial processes and can be used in the chemical and petrochemical industry at. automation of dehydration processes;

The purpose of the invention is to reduce the consumption of raw materials and energy consumption.

The drawing shows a control system for implementing the proposed method.

The consumption of raw material in the reactor is measured by sensor 1 and is controlled in the first stage 2 of the reactor by means of controller 3 and valve 4, the steam consumption 15 into the furnace is controlled by controller 5, the steam is heated in furnaces 6 and 7. The temperature of superheated steam in furnace 6 is measured sensor 8 and is controlled by the regulators 9 and, 10, and the temperature of the superheated steam in the furnace 7 is measured by the sensor 11 and regulated by regulators 12 and 13.

The temperature of the reaction mixture at the inlet of the first stage of the reactor is measured and regulated, respectively, by the sensor 14 and the regulator 15, and the composition of the contact gas after the first stage of the reactor is determined by the sensor 16 and the regulator 17. The temperature of the reaction mixture at the inlet of the second stage of the reactor after the interstage superheater 18, it is measured and regulated, respectively, by the sensor 19 and the regulator 20, and the composition of the contact gas after the second stage 21 of the reactor - by the sensor 22 and the regulator 23.

The pressure of the fuel gas supplied to the furnace 6 is measured by the sensor 2440 and is controlled by the valve 25, and to the furnace 7 by the sensor 26 and the valve 27, respectively. Steam consumption to the furnace is measured by the sensor 28 and regulated by the valve 29. In the computing unit 30 45 the calculation of energy consumption, the amount of target and by-products obtained, and in block 31 optimization - the calculation of control actions .50

The flow rate and composition of the hydrocarbon condensate are measured by sensors 32 and 33, the flow rates of uncondensed gas (exhaust gas) and fresh raw material are sensors 34 and 35. The composition of the gas entering the first stage of the reactor is measured by the sensor 36. The flow rates of the fuel gas in the furnace 6 and 7, water and ethylene

the glycol in the separation step is measured by sensors 37-40. The separation of the dehydrogenation products is carried out in apparatus 4.1.

The method is carried out as follows.

For the ethylbenzene dehydrogenation reactor to styrene, the styrene content in the contact gas after the first and second reactor stages (X and X) is stabilized. The main by-products are bentol and uncondensed gas. The optimal amount of consumption of fresh raw materials (ethylbenzene mixture) can be determined by the expression

hours

+ “Ja.п- Anпp

H)

 , CPU)

  coefficients;

 fuel gas consumption; - the amount of energy consumption

(steam, cold, water) at the dihydrogenation stage; |, - the amount of the obtained target product (styrene);

f is the consumption of fresh raw materials measured by sensor 35; Vn is the amount of by-products produced; - the amount of energy consumption

at the stage of separation; ({- the number of losses of the target product.

The amount of energy consumption in the division stage is determined by the expression (g

V3 eoA VxoA Vn "p

water flow measured

V 80A

de sensor 39; cold consumption (ethylene lol glycol) measured by sensor 40; steam consumption measured

by sensor 28.

Fuel gas consumption is defined as

t g

c

yy,

(3)

where and Vtr fuel gas consumption in furnace 6 and 7, measured by sensors 37 and 38, 3 The amount of the target product (styrene) is determined by the expression VBK-V8K ш 1, (I cr where K is the coefficient taking into account the presence of impurities in the target product , for example ethyl benzene in styrene - rectified in the production of styro VBK Hrt - styrene content in SUVK carbon-condensed carbon), measured by sensor 33; F is the consumption of hydrocarbon condensate measured by sensor 32; Xg is the styrene content in the ethylbenzene mixture, measured by sensor 36; F is the ethylbenzene charge consumption measured by sensor 1; - the amount of resin, which is D with at the separation of UVK (occupies sits in block 30 according to the result of the work of the section n stage). The amount of by-products is equal to .and Vonp 5t where x is the content of bentol in the UVK measured by sensor 33; f is the flow rate of the ACU, measured by the sensor 32; VwSr consumption of uncondensed gas (exhaust gas) measured by sensor 34. The amount of energy consumption per separation stage is determined by the expression P--, VBK UBK VBK w w h / -.jur-jors st, - - ".. + q x F 10 Bt where a - a, 5 - coefficients; xS is the content of bentol from in the ethylbenzene mixture, as measured. sensor 36. The amount of loss of the target section (styrene) is equal to CPU V with LAOLA. The optimal content of the target product (styrene) after 214 of the first and second stages of the reactor is determined by expressions: Th o or% Bt Pst "Tg. p- "1Lppr-Le 9 pi, n (T, pi-% / cT" 2a.r 25VTr "24i 2 .r - 2Lpnp 2 Vz + zlVltsp 5 where a - a2t coefficients; 1X - the content of bentol in the contact gas after the first stage reactor, as measured by sensor 16, the optimal steam consumption for dehydrogenation is equal to L. - Cpopi pt, H where K | is the proportionality coefficient. Compromise arising from control The downstream reactor for the dehydrogenation of hydrocarbon feedstocks, in particular ethylbenzene to styrene, consists in the following: The chemical parameters .xor; st opt and I-vapor, opt are determined by the expressions U), (8), (9) and (10) C2) - (, 7K dependencies At high values of |, high styrene yield to the missed ethylbenzene is achieved, energy consumption decreases, but formation of by-products increases and, as a result, large losses of raw materials. At low values of KC and xV, the formation of by-products decreases but the energy costs increase s need uvelii-iUti Cheney load F to the batch execution plan to the desired product and styrene. The distribution of the intensity of the process across the reactor, determined by the magnitudes | X and Xp, depends on the degree of influence of the distribution on the process performance. So, for example, if an increase in xj leads to a more significant increase in the formation of by-products than an increase in x, then in this case it is necessary to conduct the process more intensively in the second stage. If an increase in F leads to a more significant increase in energy consumption.

than increasing the formation of by-products in an equivalent ratio with increasing and j is necessary. decrease the F value with an increase in the respective proportions of X and J to fulfill the styrene plan.

Regulators 3 and 5 are used to stabilize the consumption of raw materials supplied to the reactor and steam. Using regulators 15, 9 and 10, the temperature of the reaction mixture at the entrance to the first stage 2 of the reactor is stabilized by changing the flow rate of the fuel gas to the furnace 6. Using the controller 17, the composition of the contact gas after the first stage of the reactor is stabilized by issuing an effect the regulator setting chamber 15. Similarly, using regulators 12, 13 and 20, the temperature of the reaction mixture at the entrance to the second stage 21 of the reactor is stabilized by changing the flow rate of the fuel gas into the furnace 7. torus 23 stabilizes the contact gas composition after

the second stage of the reactor by issuing effects in the camera setting the controller 20.

Unit 30 performs the determination of energy consumption in the dehydrogenation stage by expression (2), fuel gas consumption by expression (H), the amount of the target product by expression (.4),

the amount of by-products as expressed by expression (5), the energy consumption in the separation stage by expression (6), and the loss of the target product by expression (.7). The calculation results are transferred to

block 31, which determines the optimal values of raw material consumption by equation (1), the composition of the contact gas (content of the target product) after the first and second stages of the reactor according to equations (8 I and. (. 9), steam consumption by the expression (Yu ) with controllers (their effects in the task controllers cameras 3.17,

23 and 5.

The proposed method allows to reduce the consumption of raw materials, energy consumption and, accordingly, the specific variable technological costs by 1%. Fresh raw materials

Xapafffrfepvc / nuxiX T Koauvec / nSo SflOKO is a CMOMI eojSpamHoe division. raw material

Claims (1)

METHOD FOR CONTROL OF TWO-STAGE REACTOR. OF HYDROCARBON RAW MATERIAL DEGRADATION by controlling the composition of the contact gas after the first and second stages of the reactor by changing the temperature of the reaction mixture at the inlet of the corresponding reactor stage, depending on the consumption of raw materials in the reactor and the gas composition at the inlet of the corresponding reactor stage, regulating the flow of fresh raw materials and steam and with the fact that, in order to reduce the consumption of raw materials and energy consumption, they regulate the ratio of fresh raw materials and steam consumption by changing the consumption of steam, and the consumption of fresh raw materials and composition to ntaktnogo gas after the first and second stages of the reactor is controlled by the fuel gas flow to the furnace, amounts of energy in steps dehydrogenation and separation § Nia, number of by-produced and the desired products and the desired product losses. >