SU1491868A1 - Method of automatic control of the process of hydrogenation of acetylene hydrocarbons - Google Patents

Abstract

The invention relates to the field of automatic control of the process of hydrogenation of acetylene hydrocarbons, can be used in the refining, petrochemical and chemical industries and allows minimizing the loss of the desired product. The control circuit includes a sensor (D) 1 flow rate of ethylene fraction, D2 hydrogen flow rate, heater 3, D 4 temperature, temperature regulator (P) 5, reactor 6, chromatographs 7 and 8, adder 9, P 10 acetylene hydrocarbon concentration, extreme P 11 ethylene losses, multiplication unit 12, P13 ratios and regulators 14, 15. 1 sludge.

Description

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The invention relates to the automatic control of the process for the hydrogenation of acetylene hydrocarbons used for the purification of unsaturated hydrocarbon fractions, and can be used in the refining, petrochemical and chemical industries.

The aim of the invention is to minimize the loss of the desired product.

The drawing shows an automatic control system that implements the proposed method by the example of the hydrogenation of acetylene hydrocarbons.

The system includes an ethylene fraction consumption sensor 1 and a hydrogen consumption sensor 2 in the heater 3, at the entrance to which the ethylene fraction and hydrogen are mixed. The temperature at the outlet of the preheater 3 is measured by the sensor 4 and is maintained by the regulator 5.

The mixture of raw materials and hydrogen enters the reactor 6 with a fixed catalyst bed. The concentration of ethylene and acetylene hydrocarbons at the inlet and in the reactor code is measured using industrial chromatographs 7 and 8. In adder 9, the ethylene losses that occur due to the hydrogenation of the latter are calculated.

The system also contains a controller 10 for the concentration of acetylene hydrocarbons downstream of the reactor, an extreme controller for ethylene loss 11, a multiplication unit 12, a ratio controller 13, regulators 14 and 15 1

The method is carried out as follows.

Signals, proportional to the consumption of the ethylene fraction, from sensor 1 and the concentration of acetylene hydrocarbons in it from chromatograph 7 enter the multiplication unit 12, where the amount of acetylene hydrocarbons is calculated by the formula

BI

 /100,

(one)

Sd - the amount of acetylene hydrocarbons, Kr / 4i

 - consumption of ethylene fraction, kg / h;

C is the concentration of acetylene hydrocarbons at the inlet to the reactor, wt.%.

The consumption of hydrogen in calculating the value of Gg due to its small, compared to the consumption of raw materials,

can be neglected.

The result of calculation by the formula (1) as an input signal enters the regulator 13 of the flow ratio, where the signal from sensor 2, proportional to the hydrogen consumption, is also fed.

When the consumption of raw materials and (or) the concentration of acetylene hydrocarbons changes, the consumption of hydrogen is corrected in it.

The optimal control of the hydrogenation process is aimed at achieving the minimum loss of ethylene while maintaining the regulatory limits on the concentration of acetylene hydrocarbons in the purified fraction.

The main control actions on the processes are the flow rate of hydrogen and the temperature at the inlet to the reactor. The consumption of hydrogen is used to control the concentration of acetylene hydrocarbons at the outlet of the reactor, and the temperature at the inlet to the

a reactor to control the amount of ethylene loss.

A certain combination of the magnitude of these two control actions allows the process to be optimized in accordance with the above criteria.

To do this, a signal from chromatograph 8, proportional to the concentration of acetylene hydrocarbons at the reactor exit, is fed to the input of controller 10 as a variable. The task for regulator 10 is the routine value of the concentration of acetylene hydrocarbons in the purified fraction. The output signal from the controller 10 enters the controller 13 and adjusts the cost ratio of the raw material and hydrogen in the right direction, which leads to the elimination of the resulting deviation of the concentration of acetylene hydrocarbons from the specified value.

The signals from chromatographs 7 and 8, proportional to the concentrations of ethylene at the inlet and outlet of the reactor, are fed to adder 9, where the ethylene loss U C et is calculated by the formula

DS ,, C, - with,; . (2)

The result of the calculation as an input signal enters the extreme controller 11, which changes the setting of the temperature controller 5 in such a way as to ensure the minimum value of the controlled value & C ,.

In the process of searching for the optimum temperature, there is also a change in the flow rate of hydrogen and, ultimately, these parameters are set near the values that provide the minimum amount of ethylene loss at a given value of the concentration of acetylene hydrocarbons at the reactor exit.

Using the proposed method to control the process of hydrogenation of the ethylene fraction in the production of ethylene with a capacity of 60.0 thousand tons / go reduces the ethylene loss by 0.5-0.6%.

Claims (1)

The invention The method of automatic control of the process of hydrogenation of acetylene hydrocarbons, including the regulation of the ratio of costs of raw materials and hydrogen at the inlet of the reactor by varying the flow rate of hydrogen with correction for the concentration of acetylene compounds 0 in the reaction mixture before and after the reactor and controlling the inlet temperature of the reactor by varying the supply of heat transfer medium to the reaction mixture preheater, 5 so that, in order to minimize losses of the target product, such as ethylene, the ethylene concentration in the reaction mixture is additionally measured determined According to these concentrations, the loss of ethylene and extreme control of the loss of ethylene by the temperature at the inlet of the reactor.