SU1648946A1 - Method for automated control of production of caprolactam - Google Patents

Abstract

The invention relates to the field of automation of production processes, can be used in the chemical industry in the production of caprolactam, and allows increasing the yield in the organic phase by increasing the accuracy of controlling the pH of the reaction medium in the reactor. The method involves simultaneously supplying the ammonia water and ammonia gas to the neutralization reactor by adjusting the pH in the reactor by affecting the flow rate of ammonia water on the dependency on the consumption of caprolactam sulfate and the density of ammonia water. The method additionally measures the density of the rearranged product and the flow rate ammonia gas. From the consumption of the rearranged product and its acidity, the required amount of reducing agent is calculated for its neutralization, the change in the supply of which is carried out by the in-phase effect on the ammonia water and ammonia gas regulators, taking into account the pH in the reactor, while controlling the distribution of the ammonia water and ammonia gas by the anti-phase effect these regulators are dependent on the density of the water-sulphate layer. 1 or Ј

Description

The invention relates to the automation of industrial processes and can be used in the chemical industry in the production of caprolactam.

The purpose of the invention is to increase the yield in the organic phase by increasing the accuracy of controlling the pH of the reaction medium in the reactor.

The drawing shows the implementation of this method.

The scheme includes a neutralization reactor 1 with a circulating pump 2 and a heat exchanger 3. a settling tank separator 4,

The flow meter 5 and the acidity sensor 6 of the rearranged product, the flow meters 1 and 8, respectively, of ammonia water and gaseous ammonia, the sensors 9, 10 and 11, respectively, of the density of ammonia water, the pH value in the reactor 1 and the density of the water-sulphate layer in the separator 4, the demand calculation unit 12 in the reducing agent, a unit 13 for calculating the amount of the reducing agent, a comparison circuit 14, a controlled amplifier, actuators 16, 17 and control valves 18, 19 on the line of ammonia water and gaseous ammonia, respectively, as well as an amplifier inverter 20.

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The method is carried out as follows.

The rearranged product is fed to the neutralization reactor 1 through the flow meter 5. The acidity of the rearranged product stream entering reaction 1 is measured by sensor 6. The signals from sensors S and 6 are fed into block 12, the output signal of which is the calculated amount of ammonia required, is fed to the 1st input of the comparison circuit 14, to the second input of which the signal from the output of block 13 is generated. Block 13 generates a signal of the amount of reducing agent fed to the reactor 1 in the form of ammonia water and gaseous ammonia based on sig at 7 and 0 sensors, respectively, of ammonia water and ammonia gas, and ammonia water density sensors 9.

The output signal of the comparison circuit 14 through the variable gain amplifier 15 acts in phase with the actuators 16 and 17 in such a way that the valves 18 and 19 are opened on the supply lines of ammonia water and gaseous ammonia, respectively, with a shortage of reductant, and in case of its excess closes. The presence of an open servo loop can significantly improve the accuracy and speed of the control system. When a disturbing action appears in the form of a change in the value of the flow of the rearranged product or its acidity, the following loop along the chain: block 12 — comparison circuit 14 — amplifier 15 — actuators 16, 17 and valves 18, 19 — did not wait for the change in magnitude The pH in the reactor 1 will compensate for the flow of the reducing agent. A slight change in the pH value, taking into account the lag time, is measured by the sensor 10 and the supply amount of the reducing agent is adjusted by changing the gain of the amplifier 15 in the appropriate direction.

The mixing of the reactants in the reactor 1 is carried out by circulating the mixture with the pump 2. The heat of neutralization and dissolution of ammonia is removed in the heat exchanger 3. The neutralized product is transferred by overflow to the separator 4 separator, in which the upper (organic) layer is separated from the water-sulphate layer delamination The delamination process deteriorates as the concentration of ammonium sulfate in the water layer decreases.

The density of the water-sulphate layer in the separator 4 is measured by the sensor 11, while depending on the ammonium sulphate concentration in it, the flow of ammonia water and gaseous ammonia is redistributed by changing the factors of the actuators 16 and 17 through the inverter amplifier 20.

When the ammonium sulfate concentration in the water layer of the separator A drops, the gain of the actuator 16 decreases and the actuator 17 increases, while the flow of ammonia gas increases compared to the ammonia water supply. As the concentration of ammonium sulfate in the water layer of the separator 4 increases, The precipitation of ammonium sulfate crystals, respectively, increases the proportion of ammonia water supply compared with ammonia gas supply.

The application of the method in the production of caprolactam with a capacity of 50 thousand tons per year at the stage of neutralization allows to increase the percentage of the yield in the organic phase from 96.5-97% to 97.5-98%, i.e. on average 1%

Claims (1)

Invention Formula A method of automatically controlling the process of caprolactam production, including regulating the pH of the reaction medium in the reactor, neutralizing it by changing the ammonia water supply with correction for the flow rate of the rearrangement product fed to the reactor and the density of ammonia water and regulating the ammonia gas supply to the reactor, characterized by that, in order to increase the yield in the organic phase by increasing the accuracy of controlling the pH of the reaction medium in the reactor, the concentration ammonium sulfate (density) in the water-sulphate layer in the settling tank separator and the acidity of the rearrangement product, using the measured values of the consumption of the rearrangement product and its acidity, calculate the required amount of reducing agent for its neutralization, using the measured values of ammonia water consumption, its density and consumption gaseous ammonia is calculated the current value of the amount of reducing agent supplied to the neutralization, compare this calculated current value of the amount of reducing agent with the calculation At the calculated current value of the amount of the reducing agent, less than the calculated required value, the supply of ammonia water and gaseous ammonia to the reactor is increased, and at the calculated current value of the amount of reducing agent, more than the calculated required value, the supply of ammonia water to gaseous ammonia to the reactor is reduced, with a decrease in the concentration of ammonium sulfate in the water-sulfate layer increase the flow of gaseous ammonia and reduce the flow of ammonia water, and with increasing concentration radio ammonium sulfate in the aqueous sulfate layer reduces the supply of ammonia gas and increase the supply of ammonia water. Regrouping Product Gaseous aimiak Laktan Yoda water slurry