Continuous preparation system and method for vinylidene chloride

Patent metadata

Field	Value
Publication number	US-12134081-B2
Application number	US-202118258616-A
Country	US
Kind code	B2
Filing date	Dec 24, 2021
Priority date	Dec 25, 2020
Publication date	Nov 5, 2024
Grant date	Nov 5, 2024

Abstract

The present application provides a continuous preparation system and method for vinylidene chloride. In the present application, by coupling two stages of high gravity reactors, the product vinylidene chloride and water vapor are distilled from a reaction system in form of an azeotrope by adopting a water vapor steam stripping method, and the product obtained using the method has high purity. In addition, by combining steam stripping and high gravity, trichloroethane and alkali solution are rapidly mixed for mass transfer, and the product vinylidene chloride is rapidly distilled from the reaction system in form of the azeotrope (based on rapid diffusion of water vapor), such that the reaction proceeds continuously towards the direction of producing vinylidene chloride, thus significantly improving the conversion rate. As proved by a test apparatus, the present application can stabilize the purity of the vinylidene chloride product at 98% or more (mass fraction), decrease the TOC value of chloride salt wastewater to 100 mg/L or less, and decrease the consumption of materials and the cost of subsequent salt-containing wastewater treatment.

First claim

The invention claimed is:

1. 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.

2. The continuous preparation method according to claim 1 , wherein the stirred tank is communicated with the liquid inlet of the first high gravity reactor through a second branch pipeline, and the continuous preparation system further comprises:
a first valve located on the first branch pipeline; and
a second valve located on the second branch pipeline.

3. The continuous preparation method according to claim 2 , wherein the continuous preparation system further comprises:
a valve controller coupled with the first valve and/or the second valve and configured to control the opening of the corresponding valve.

4. The continuous preparation method according to claim 3 , wherein the continuous preparation system further comprises:
a detector configured to detect flow rate at the liquid inlet pipeline of trichloroethane and alkaline solution; and
a processor configured to determine the opening of the corresponding valve according to the flow rate.

5. The continuous preparation method according to claim 1 , wherein the first high gravity reactor and the second high gravity reactor are rotating packed beds.

6. The continuous preparation method according to claim 5 , wherein oleophobic packings are provided in the rotating packed beds.

7. The continuous preparation method according to claim 6 , wherein a plurality of run-through micropores are formed in the oleophobic packings.

8. The continuous preparation method according to claim 1 , wherein the micropores are of micro-nano scale.

9. The continuous preparation method according to claim 1 , wherein the gas inlet of the first high gravity reactor is located in a sidewall of the first high gravity reactor and is directed to the inside of the packings.

Assignees

• Zhejiang Quzhou Jusu Chemical Ind Co Ltd
• Univ Beijing Chem Tech
• Juhua group co ltd

Inventors

• Zhang Liangliang
• Zhou Liyang
• Chu Guangwen
• Lin Jinyuan
• Tong Jihong
• Chen Jianfeng
• Zhang Yidong
• Wu Zhigang
• Yu Yunfei

Classifications

• C07C17/25 Primary

  by splitting-off hydrogen halides from halogenated hydrocarbons · CPC title

• B01J2219/00164

  controlling the flow · CPC title

• B01J2219/00038

  Processes in parallel · CPC title

• B01J19/1856

  placed in parallel · CPC title

• B01J19/0006

  Controlling or regulating processes (controlling or regulating in general G05) · CPC title