SU1504245A1 - Method of controlling the process of benzine pyrolysis in tubular furnaces - Google Patents

Abstract

The invention relates to controlling the production of ethylene, can be applied to control the process of pyrolysis of gasoline to produce ethylene, propylene, butylene-divinyl fraction and allows to increase the yield of the target product by increasing the period of operation of the furnace. In the proposed method, the concentration values of aromatic hydrocarbons in gasoline are measured, compared to the nominal value of this concentration according to the regulations, and if it is rejected to a larger extent, the partial pressure of hydrogen in the pyrogas at the furnace exit is affected by affecting the ratio of gasoline consumption and hydrogen at the inlet to stove, and when it is deflected downwards in proportion to increase the consumption of gasoline in the stove. 1 ill., 1 tab.

Description

The invention relates to controlling the production of ethylene and can be used to control the process of pyrolysis of gasoline to produce ethylene, propylene, butylene-divinyl fraction, and the like.

The aim of the invention is to increase the yield of the target product by increasing the duration of operation of the furnace.

The drawing shows a block diagram of a system for automatically controlling the process of pyrolysis of benzyl in tube furnaces, which makes it possible to implement the proposed method.

The system contains pipelines for supplying gasoline 1, steam 2 and hydrogen 3 coils of pipes 4, furnace 5, pipe 6 for outputting a pie-ase, flow sensors of a 7-cylinder 7f steam l 8 and hydrogen 9i

regulators 10 and II ratios, control valves 12-14, sensor I5 of aromatic hydrocarbon concentration in gasoline, comparative block 16, computing blocks 17-19, sensors 20 of hydrogen concentration in pyrogas and pyrogas pressure 21, regulator 22 of gasoline consumption, regulator 23 partial pressure of hydrogen in pyrogas, pipe 24 for supplying fuel gas to the furnace.

Channel A connects the first output of the comparison unit 16 with the computing unit 17, channel B connects the second output of the comparison unit 16 to the computing unit 19.

Computing blocks 17 and 19 are constructed so that if the concentration of aromatic hydrocarbons in gasoline is greater than or equal to a given concentration of

four

Yu

1 ate

of these products according to the regulations, the computing unit 19 is automatically turned off, and if less, the computing unit 17 is automatically turned off.

The automatic control system that implements the proposed method works as follows.

When the concentration of aromatic hydrocarbons in gasoline measured by sensor 15 is increased in comparison with the nominal one, the computing unit 17 is automatically turned on, and 19 is turned off. The controller 23 receives two signals: one of them as a variable from the computing unit 18, and the other as a task from the computing unit 17. The error signal from the controller 23 enters the controller 1 1 as} 1 and the consumption of gasoline and hydrogen in as a task. Regulator 2 has an astatic regulation law. Therefore, it changes the cost ratio of gasoline and hydrogen until the signals from computing blocks 17 and 18 are equal in magnitude, i.e. the current value of the partial pressure of hydrogen in the pyrogas, calculated by the computing unit 18, will not be equal to the specified value. The specified value of the partial pressure is calculated by the computing unit 17 according to the formula

Р ° К, ud f С,

where K, 0.465, C 0.372 are constant numbers determined experimentally;

4o / A - the increment of the concentration of aromatic hydrocarbons in gasoline, measured by the sensor 15.

The value of o (d is calculated by block 16 comparison by the formula

L.

 - 0

 - aromatic concentration

hydrocarbons in gasoline, measured by sensor 15; o / d - the same as specified by the regulations.

The regulator 23 operates in the event that up to (d / 0. Then the comparison unit 16 sends a signal proportional to j 0 5 C J

Q

.

0

five

the value of L (/, on channel A. If Lo (/ O, then the signal goes on channel B to the computing unit 19.

The current value of the partial pressure of hydrogen in the pyrogas computing unit 18 calculates on the basis of the signals coming from the output of sensors 20 and 21, proportional to the values of the concentration of hydrogen in pyrogas and pyrogas pressure by the formula

four

where P is the partial pressure of hydrogen in pyrogas; P - pressure pyrogas; hydrogen concentration in pyrogas at the kiln outlet. At steady state, equality is ensured

about

p. 2 Nz

The required gas mileage is calculated by the computing unit 19

formula

Qg Kj / lo / b,

where K -1,666, b 20,0 - constant

determined experimentally. Computing Output

block 19 proportional to the value

Q ,, enters flow regulator 22

gasoline as a task, and the latter proportionally increases the consumption of gasoline. The limiting value of gasoline consumption is its maximum value according to the technical regulations. Therefore, when setting up the computing unit 19, it is necessary to reconcile the maximum deviation of the concentration of aromatic hydrocarbons from the nominal value downwards with the maximum consumption of gasoline in the furnace. For example, the maximum consumption of gasoline .Qrf-H.Kc 25 t / h prio / „5%; ; j 8%,

hence yo (5-8 -3%. With the experimentally found value of K -1.666 and b 20.0.

(ff -1.666 (-3) - 20 25 t / h.

Prio (LMS. 12%, 12-8 4%, therefore, PH 0.0465 x 0.372

 0.1860 0.372 0.358.

The table shows the comparative analysis of the performance of the process of the prototype and the proposed method.

Duration of the work period

furnace, days 42.0 42.2 Increase the productivity of the installation in ethylene, wt.% 24.2 24.61

The table shows that the introduction of the method in the production of EP-300 allows to increase the duration of the furnace and its performance on the target product.

The economic effect from the implementation of the proposed method will be more than 80.0 thousand rubles. in year.

Claims (1)

Invention Formula The method of controlling the pyrolysis process of gasoline in tube furnaces, which consists in controlling the magnitude of the ratio of gasoline and steam consumption by affecting steam consumption, the ratio of gasoline consumption and hydrogen affecting hydrogen consumption At the entrance to the furnace, characterized in that, in order to increase the yield of the target product, In addition, the concentration of aromatic hydrocarbons in gasoline is measured; it is compared with the nominal value of this concentration in accordance with the regulations and when it is deflected to a greater extent, the proportions tional increase the hydrogen partial pressure in the pyrolysis furnace at the outlet of the influence on the value of the ratio of hydrogen and gasoline raskhoov inlet into the oven, and rejecting it in smaller side increase the consumption of gasoline in the oven.  L 3 --® well eight L 20 If