How to Recover Chlorobenzene from Waste Water with Valves?

Chlorobenzene is the raw material for the production of P-nitrochlorobenzene and O-nitrochlorobenzene, and the primary derivative of P-nitrochlorobenzene and O-nitrochlorobenzene is an important intermediate in rubber, dye, pigment, agrochemical and pharmaceutical production. Recovering chlorobenzene from waste water is an environment-friendly production method. The following content describes how to recover chlorobenzene from waste water by using valves.

Production Principle of Chlorobenzene

The reaction principle of the liquid-phase catalytic chlorination method is to chlorinate the benzene in the dark and boiling state with ferric trichloride as the catalyst. The heat generated by the reaction is transferred out by the vaporization of excess benzene.

Purification of Crude Chlorination Solution

The chlorinated benzene generated from the chlorination tank of the reactor is sent to the inlet pipeline of the pump together with the unreacted raw material benzene. Most of the water contained in the highly absorbent chlorinated solution of hydrogen chloride is absorbed by water and then sent to the lower part of the water washing tank. After static separation, it overflows from the upper part of the water washing tank to the lower part of the water washing tank. The coarse chlorination liquid from the middle and upper part of the water washing tank is mixed with the liquid alkali by the alkali washing pump, which is then mixed by the pipeline mixer and delivered to the alkali washing tank to be static and separated into the slightly alkaline fine chlorination liquid. The fine chlorination liquid overflows from the upper part of the alkali washing tank to the bottom of the fine chlorination liquid tank through the pH meter, and then overflows from the upper part of the fine chlorination liquid tank to the bottom of the fine chlorination liquid tank.

Waste Water Generation and Environmental Protection Recovery

The refined process of crude chlorination liquid mainly uses the extraction principle that the solubility of water and hydrochloric acid is higher than that of chlorination liquid and hydrochloric acid, so that a large amount of hydrochloric acid entrained in the production process of chlorination liquid is absorbed by water and then removed. The subsequent alkaline washing process is to use the proportioned NaOH solution to continue to extract and at the same time increase the neutralization reaction between acid and alkali to completely remove the acid in the chlorinated liquid.

All the alkaline waste water discharged from the alkali washing tank is mixed with the clean water used for water washing and then sent to the chlorination solution for primary water washing. The neutralization reaction between the mixed clear water and the acid ion in the chlorination solution is more complete, so that the alkali washing and water washing can be carried out at the same time. When the chlorinated liquid after water washing enters the alkali washing tank, only the pH value needs to be adjusted to ensure the pH value. This operation is relatively successful, no abnormality is found during the trial operation for two years, and the use of NaOH liquid alkali is reduced while the waste alkali water is effectively used to reduce the discharge of waste water.

Compared with the traditional method, the recovery of chlorobenzene from waste water not only reduces the investment in valves（chlorine shut-off valve and chlorine hand operated valve）, equipment andpipe fittings, but also reduces the environmental pollution. It is a low investment, no operation cost method.