Periodic automatic control method for preparing chloroacetic acid

Abstract

The invention discloses a periodic automatic control method for preparing chloroacetic acid. A device comprises a reactor, an electric valve I, a chlorine flow meter, a temperature sensor and a pressure sensor. The electric valve I, the chlorine flow meter, the temperature sensor and the pressure sensor are connected with a DCS (distributed control system). The method includes firstly, dividing a whole reaction process into a plurality of stages; secondly, setting chlorine accumulated filling quantity Qi and chlorine rate value Vi of each stage in the DCS; thirdly, regarding the chlorine accumulated filling quantity Qi as a separation point of each reaction stage; fourthly, entering the next stage when chlorine accumulated filling quantity of the certain stage reaches the set chlorine accumulated filling quantity Qi of the stage; and fifthly, finishing reaction until the chlorine accumulated filling quantity Qi reaches set chlorine accumulated filling quantity Q of a whole chlorination endpoint. Periodic chlorination with manual monitoring required conventionally is changed into automatic control. The reaction process is judged by measuring accumulated flow of chlorine consumed by chlorination in the reactor, and the reaction endpoint is judged according to gross data of consumed chlorine. The control method can implement automatic control, and reaction result and reaction product are more accurate.

Description

technical field [0001] The invention relates to a chemical process, in particular to an automatic control method for preparing chloroacetic acid with chlorine and acetic acid as raw materials and sulfur as a catalyst. Background technique [0002] The preparation process of chloroacetic acid, which uses chlorine gas and acetic acid as the main raw materials and sulfur as the chlorination catalyst, is a dangerous chemical process. The State Administration of Work Safety requires automatic transformation to reduce on-site operators and avoid safety accidents of casualties. At present, the above-mentioned process for preparing chloroacetic acid mainly uses an intermittent chlorination process. The intermittent chlorination process of chloroacetic acid is as follows: acetic acid comes from a storage tank, and is added to the chlorination reaction kettle at one time after the metering tank. The catalyst sulfur is also a one-time Add in the reaction kettle, only chlorine is consta...

AI Technical Summary

Problems solved by technology

[0003] The existing process judges the reaction process and the reaction end point by the reaction density. Due to the error of the operator's measurement, it is easy to affect the judgment of the process, which increases the consumption of chlorine gas, and the large amount of on-site operations by the operator poses a safety hazard.

The existing intermittent chloroacetic acid process cannot quantify the amount of chlorine gas introduced in each reaction process stage, and the method of controlling the reaction process by measuring the density cannot be converted into an automatic control method