SU1527231A2 - Method of automatic control of reactor for dehydrogenation of initial hydrocarbons - Google Patents

Abstract

The invention relates to devices for the automatic control of technological processes in fixed-bed multilayer adiabatic reactors with a fixed catalyst bed, an improvement of the known device described in the authors. N 1263690, and allows you to increase the yield of the target product. The device contains sensors 3,6 and 9 of consumption of raw materials, steam and oxygen, controllers 4, 7, 10, 18, computing unit 13, comparison unit 14, temperature setting unit 15, oxygen consumption setting unit 16 and switching relay 17. 2 Il.

Description

(L

Yu

14)

The invention relates to devices for the automatic control of technological processes in multi-layer adiabatic fixed bed reactors and is an improvement of the device according to Aut. No. 1263690,

The aim of the invention is to increase the yield of the target product,

Fig, 1 shows the block diagram of the device; FIG. 2 shows the temperature profile in the reactor.

The device contains a sectional adiabatic reactor 1 for dehydrating hydrocarbon feedstock with fixed catalyst beds (Fig 1), a mixer 2, a sensor 3, a regulator 4 and a control valve 5 for raw materials consumption, a sensor 6 for steam consumption, a regulator 7 for the ratio of raw materials consumption steam, steam flow control valve 8, sensors 9, controllers 10 and stage oxygen flow control valves 1I, temperature sensors 12, computing unit 13, multichannel comparison unit 14 for temperature setting unit 15, oxygen setting task unit 16 zduha m stages of the reactor, a multi-channel relays 17, switching regulators 18, temperature regulating valve 19, the refrigerant flow in the interlayer heat exchanger, the heat exchanger 20,

The device works as follows.

Information on the consumption of raw materials and steam, measured respectively by sensors 3 and 6, is fed simultaneously to the inputs of the controller 4 of the consumption of raw materials and controller 7 of the ratio of the consumption of raw materials and steam, which varies steam consumption depending on the consumption of raw materials, and input of the computing unit 13, to the other inputs of which information is received from the temperature setting unit 15 and from the temperature sensors 12 in the fixed catalyst bed. In the computing unit 13, a mathematical model of the process is solved, which has the following form

 Q F (Qc, Qn,); F (Qc, Qn, T2, TB);

tG F (Qc, iK

where T ,, Tj - the current value of

5 0 5 o

Q Q

five

peratur in each layer of the reactor; T, - the initial value of dark

perature;

T is the maximum value of the outlet temperature

layer:

5ad hell Q, Q - specified calculated

values of air oxygen consumption by layers;

QC current value of raw materials and steam consumption. This mathematical model of the dehydrogenation process allows to determine the optimal amount of oxygen supplied to each reactor bed and the required amount of refrigerant supplied to the interlayer heat exchanger to maintain the step temperature of the section adiabatic reactor. To do this, the computing unit comes from sensors 3 and

12 information. In the computing unit 13, the problem of theoretical optimization is solved on the basis of this information and the mathematical model, where

for a given initial temperature T, the upper level of temperature Tg is calculated. Then, for the Tg value found, the required amount of oxygen of the air supplied to each layer of the reactor is determined. For this, the initial oxygen distribution of the air is introduced into the computing unit. 13 using a multichannel unit 16 to set the air flow rate of air over the layers and calculate the temperature distribution over the layers.

Signal from computing unit

13 enters the multichannel unit

14, where it is compared with the signal from the temperature setting unit 15, the value of which is determined

in the process of solving the optimization problem, and is optimal for this mode in the reactor. If the magnitude of the signal at the output of computing unit 13 differs from the magnitude of the signal at the output of block 15, the oxygen distribution in block 16 changes until the error signal disappears at the exit of block 14. When the mismatch signal disappears, the switching relay 17 opens and passes signals from the unit 16 for setting the air flow rate of oxygen, which as a task goes to the regulators 10. The second input of the regulators 10 is supplied with information from the sensors 9, and, by its outputs of the regulators 10, control valves 11, maintain the required temperature in the reactor. In addition, in the computational unit 13, according to a mathematical model, the optimal temperature follower is 0.65 mol and Qj is 0.9 mol and ipo; as a task, it goes to the regulators 10, to the second input of which information is supplied from the sensors 9, and, acting on the control valves 11, maintains the required temperature in the reactor. In addition, in the computing unit 13, a temperature sequence in the interlayer space T. j is determined, which is fed to the first input and regulates the temperature chart 18 as a task. At the second entrance

in the interlayer space of the reaction-temperature signal

torus, which are fed to the first inputs of the temperature controller 18 as a task. The second inputs of the temperature controller 18 receive a signal from the temperature sensor 12. When these signals are not matched, a signal appears at the output of de controller 18, which, acting on control valve 19, changes the amount of refrigerant supplied to the intersectional heat exchanger 20,

As an example, we present the results of the calculation of the process of oxidative dehydrogenation of isoamelins into isoprene.

Information on the consumption of raw materials and steam, measured by sensors 3 and 6, is simultaneously fed to the inputs of controller 4 of raw materials consumption and controller 7, the ratio of raw materials to steam consumption (1:20), and then through mixer 2 to the first layer of the reactor and to the input of the computing unit 13, to the other inputs of which information is received from the temperature sensors 12 and from the temperature setting unit 15. The computing unit 13 solves the problem of theoretical optimization, where by .-- "

TA iO C; computed value on

the input values of J. f () C, 440 ° C, calculate the output value Tb 600 ° C. For the Tg value found, determine Q,

from temperature sensor 12. At the output of the regulator 18, a signal appears that acts on the control valve 19, feeding into the heat exchanger 20 a calculated amount of refrigerant equal to 65,400 m / h.

The use of the invention in the process of oxidative dehydrogenation of isoamylenes to isoprene allows to increase the yield of isoprene to 54%,

Claims (1)

Invention Formula A device for automatic control of a hydrocarbon dehydrogenation reactor according to the model, no. 1263690, characterized in that, in order to increase the yield of the target product, heat exchangers along the reactor stages, refrigerant supply valves for the heat exchangers and temperature regulators are additionally introduced into it PS with temperature sensors connected to the first inputs of the temperature controller along the reactor stages, the second inputs of which are connected to the second output of the computing unit, and the outlets are equipped with refrigerant supply valves to heat exchangers along the steps of the reactor. n - Fig2 0.6 Ggvg