Continuous preparation system and method for vinylidene chloride

A continuous preparation method for vinylidene chloride, applied to a continuous preparation system for vinylidene chloride, wherein the continuous preparation system comprises:

• a first high gravity reactor, a liquid inlet of the first high gravity reactor being communicated with a liquid inlet pipeline of trichloroethane and alkali solution, a gas inlet of the first high gravity reactor being communicated with a water vapor pipeline;
• a stirred tank, a liquid inlet of the stirred tank being communicated with a liquid outlet of the first high gravity reactor, a gas inlet of the stirred tank being communicated with a gas outlet of the first high gravity reactor, the stirred tank being communicated with an external product storage tank through a first branch pipeline;
• a second high gravity reactor, a liquid outlet of the second high gravity reactor being communicated with a liquid inlet of the stirred tank, a gas inlet of the second high gravity reactor being communicated with a gas outlet of the stirred tank;
• and
• a condensation circulation pipeline, the condensation circulation pipeline and a gas outlet and gas inlet of the second high gravity reactor forming a condensation loop;
• the continuous preparation method includes the following steps:
• a. raw materials 1,1,2-trichloroethane and alkaline solution are continuously added to the first high gravity reactor according to a certain ratio, and are fully mixed for rapid reaction;
• at the same time, water vapor is continuously fed into the first high gravity reactor to exchange heat with the reaction material liquid;
• b. the product vinylidene chloride and unreacted 1,1,2-trichloroethane in the material liquid of the first high gravity reactor are heated and gasified, then carried out by water vapor from the top of the first high gravity reactor, and then are fed into the stirred tank from the bottom of the stirred tank;
• remaining material liquid, which remains in the first high gravity reactor after the product vinylidene chloride and the unreacted 1,1,2-trichloroethane in the material liquid of the first high gravity reactor are heated and gasified, flows out from the bottom of the reactor and then flows into the stirred tank from the top;
• c. the gas and liquid discharged from the first high gravity reactor are in countercurrent contact in the stirred tank for full mass and heat transfer, most of trichloroethane entrained in the gas is washed into the liquid phase, and most of dissolved vinylidene chloride in the liquid is stripped into the gas phase by steam, after contacting, the gas is discharged from the top of the stirred tank and the liquid is discharged from the bottom of the stirred tank;
• d. the liquid discharged from the bottom of the stirred tank is divided into two streams according to a certain ratio, one stream is used as circulating liquid and is circulated back to the first high gravity reactor through the circulating pump, the other stream is used as solution for chloride, which is a byproduct of the reaction of the 1,1,2-trichloroethane and the alkaline solution, to produce a byproduct chloride solution, and the byproduct chloride solution is neutralized by hydrochloric acid and then is extracted;
• e. the gas discharged from the top of the stirred tank is fed into the second high gravity reactor, where it fully contacts and is mixed with reflux condensate to separate a heavy component and a light component;
• the heavy component is liquefied under the cooling of the reflux liquid in the second high gravity reactor, is discharged from the bottom of the second high gravity reactor, and is fed into the stirred tank as circulating liquid;
• the light component is discharged from the top of the second high gravity reactor in a gasified state;
• and
• f. the light component gas discharged from the top of the second high gravity reactor passes through a condenser and becomes liquid of the product vinylidene chloride, then, the liquid is divided into two streams according to a certain ratio, one stream is fed into the second high gravity reactor as circulating liquid, which is used as the reflux condensate, the other stream is extracted as the vinylidene chloride product.