SU1234395A1 - Method of controlling process of dimethyldioxane synthesis - Google Patents

Description

I

The invention relates to the automation of the reaction processes of chemical technological productions, in particular, the production of isoprene, and can be used in the chemical and petrochemical industry in automating the synthesis of dimethyl dioxane.

The purpose of the invention is to increase the accuracy of maintaining a given reactor throughput for the target product.

The introduction of temperature control in the upper part of the reactor by influencing the flow of condensate with correction by the values of heat fluxes at the inlet and outlet of the reactor allows regulating the temperature conditions along the height of the reactor and indirectly controlling the selectivity of the process, which improves the accuracy of maintaining the desired performance for the target product and reducing unit costs of raw materials.

The drawing shows a schematic diagram of the automatic control of the synthesis of dimethyldioxane, which implements this method.

The formaldehyde charge enters the lower part of the reactor 1, into which the hydrocarbon fraction is passed, previously passed through the heat exchanger 2 g. The consumption of the hydrocarbon fraction and the formaldehyde charge is measured by sensors 3 and 4. The compositions of the hydrocarbon fraction and the formaldehyde charge are measured by analyzers (sensors) 5 and 6 The temperature of the hydrocarbon fraction and the formaldehyde mixture is measured by sensors 7 and 8. The temperature in the lower part of the reactor, measured by sensor 9, is controlled by regulator 10 by acting on valve P. Temp. The temperature in the upper part of the reactor, measured by sensor 12, is controlled by regulator 13 by acting on valve 14. Condensate flow to the reactor is measured by sensor 15. Condensate temperatures at the reactor inlet and outlet are measured by sensors 16 and 17. The control system also contains a block 18 controlling the ratio of formaldehyde consumption in the charge and isobutylene in the hydrocarbon fraction fed through valve 19, unit 20 for temperature correction in the lower part of the reactor, unit 21 for calculating the heat flow at the inlet

343952

reactor, block 22 for calculating the heat flux at the reactor outlet and block 23 for calculating the specific heat release of the dimethyldioxane synthesis reaction

5 correction of the temperature controller setting in the upper part of the reactor.

The control method is carried out in such a manner.

Signals from flow sensors 3 and 5

® and the composition of the hydrocarbon fraction and the sensors 4 and 6 of the flow rate and the composition of the formaldehyde mixture are fed to the input of the ratio control unit 18, which affects the

5 pan 19 hydrocarbon feed. Using correction block 20, a correction correction is set to set temperature controller 10 in the lower part of the reactor to be proportional to

0 C5gmme costs formaldehyde charge and hydrocarbon fraction. In block 21, the signals from the sensors 5 and 8 of the flow rate and temperature of the hydrocarbon fraction and the sensors 4 and 7 of the flow rate and temperature of the formaldehyde charge are used to calculate the heat flux at the reactor inlet

where G, C, t - consumption, specific

0 heat capacity and temperature of the hydrocarbon fraction; GU ,, Sf., T - consumption, specific

heat capacity and temperature of the formaldehyde mixture.

In block 22, signals from sensors 3 and 4 of the hydrocarbon fraction and formaldehyde charge, sensor 12 at the top of the reactor, sensor 15 of condensate flow into the reactor, and sensors 16 and 17 of the condensate temperature at the inlet and outlet of the reactor are calculated on the output heat flow from the reactor

Qb (G, -t-G) C (t, -t, J, where C is the specific heat capacity of the reaction mixture;

0 t is the temperature in the upper part of the reactor;

G, is the consumption of condensate in the reactor;

Ch. K. Condensate temperature at the inlet and outlet of the reactor.

In block 23, the signal from the sensors 4 and 6 of the flow and composition formalde0

five

55

3

Hydraulic charge and output signals from blocks 21 and 22 calculate the specific heat output of the dimethyldioxane synthesis reaction per ton of formaldehyde supply Q, and then the correction value Atg for setting the temperature regulator 13 in the upper part of the reactor:

n -9i.Qa,

9 Atb

(Q ,, - Q., S-9 to

where X is the formaldehyde concentration in the mixture;

Editor L. Pchelinska

Order 2951/29 Circulation 379

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

O

- specified specific value

heat gap; K - coefficient of proportionality.

The utj correction is given to the controller discretely with an interval of not less than the duration of the transition process in the reactor. The magnitude of a given specific heat release is selected taking into account the requirements for process selectivity, which has a close correlation with heat generation.

Compiled by G. Ogadzhanov

Tehred L. Serdyukova Corrector. Shekmar

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Claims (1)

METHOD FOR CONTROLLING DIMETHYLDIOXANE SYNTHESIS PROCESS by controlling the temperature in the lower part of the reactor by affecting the steam supply to the hydrocarbon heat exchanger with correction for the consumption of formaldehyde charge and hydrocarbon fraction, the ratio of formaldehyde consumption in the charge and isobutylene in the hydrocarbon fraction by affecting the supply of the hydrocarbon fraction to the reactor a reactor, characterized in that, in order to increase the accuracy of maintaining a given reactor performance for the target product, the temperature of the hydrocarbon fraction, formaldehyde charge, condensate at the inlet and outlet of the reactor, the product in the upper part of the reactor and the condensate flow rate are measured, the value of the heat flow at the inlet of the reactor is determined from the measured flow rates and temperatures of the hydrocarbon fraction and the formaldehyde charge, from the measured flow rates of the hydrocarbon fraction , formaldehyde charge and condensate and product temperatures in the upper part of the reactor, condensate at the inlet and outlet of the reactor determine the amount of heat flow at the reactor outlet, from the measured values of the consumption of formaldehyde charge and the amount of formaldehyde in it and the calculated values of the heat flux at the inlet and outlet of the reactor, the specific heat release in the reactor is determined and the product temperature in the upper part of the reactor is controlled by changing the condensate supply with a correction proportional to the deviation of the calculated value specific heat in the reactor from a given value. "SU ... 1234395