A system for separating toluene from gaseous phosgene

Abstract

The utility model relates to a system of separating toluene in gas phase phosgene, and absorption tower top connects liquid phase toluene feed pipe, absorption tower kettle connects phosgene inlet pipe, absorption tower top gas phase export connects exhaust pipe, exhaust pipe accesses cyclone separator, and cyclone separator top gas phase export accesses phosgene destruction system, absorption tower kettle bottom liquid phase export connects absorption liquid recovery pipe, and absorption liquid recovery pipe accesses analytical tower, and absorption liquid toluene is used to absorb the phosgene gas not condensed in phosgene synthesis reaction in absorption tower, and the phosgene not absorbed enters phosgene destruction system after separating through cyclone separator. This can not only reduce toluene consumption, but also can recover part phosgene, reduce raw material consumption and save production cost. At the same time, the recycling of toluene reduces the content of organic matter in waste water system, and eliminates the security risk to a certain extent.

Description

Technical Field

[0001] This utility model belongs to the field of chemical technology equipment, and specifically relates to a system for separating toluene from gaseous phosgene. Background Technology

[0002] Currently, the gaseous phase produced by phosgene synthesis is directly fed into the phosgene destruction system. This process has the following drawbacks: Firstly, toluene entrained in the exhaust gas at the top of the absorber is not recovered, resulting in toluene waste. Secondly, the exhaust gas enters the phosgene destruction system, and the increased toluene content in the resulting wastewater leads to an increase in the total organic carbon (TOC) of the wastewater, thus polluting the environment. Furthermore, toluene is a flammable and explosive substance, and its accumulation in the wastewater system poses a safety hazard to production. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a system for separating toluene from gaseous phosgene.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a system for separating toluene from gaseous phosgene, comprising an absorption tower, a liquid toluene feed pipe connected to the top of the absorption tower, and a phosgene feed pipe connected to the bottom of the absorption tower. The system is characterized in that: the gas phase outlet at the top of the absorption tower is connected to an exhaust pipe, which is connected to a cyclone separator; the gas phase outlet at the top of the cyclone separator is connected to a phosgene destruction system; the liquid phase outlet at the bottom of the absorption tower is connected to an absorbent recovery pipe, which is connected to a desorption tower; the absorbent toluene is used to absorb uncondensed phosgene gas from the phosgene synthesis reaction entering the absorption tower; the unabsorbed phosgene is separated by the cyclone separator and then enters the phosgene destruction system.

[0005] The liquid phase outlet at the bottom of the cyclone separator is connected to the absorbent recovery pipe. The liquid toluene separated by the cyclone separator is sent to the desorption tower to achieve the recycling of toluene.

[0006] The beneficial effects of this invention are as follows: A cyclone separator is added to the design, separating the exhaust gas from the top of the absorption tower into gas and liquid phases. The separated liquid toluene (or toluene containing phosgene) and the bottom liquid (toluene containing phosgene) enter the toluene / phosgene stripping tower together, while the gas phase is discharged to the phosgene destruction system. This not only reduces toluene consumption but also recovers some phosgene, reducing raw material consumption and saving production costs. Simultaneously, the recovery and reuse of toluene reduces the organic matter content in the wastewater system, eliminating safety hazards to some extent, and significantly reducing the TOC content of acidic and alkaline wastewater, thus lowering wastewater treatment costs and having significant implications for environmental protection. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the present invention; In the diagram: 1-Absorption tower, 2-Cyclone separator, 3-Liquid toluene feed pipe, 4-Phosgene inlet pipe, 5-Exhaust pipe, 6-Absorbent liquid recovery pipe. Detailed Implementation

[0008] The principles and features of this utility model are described below with reference to the accompanying drawings. The examples given are only for explaining this utility model and are not intended to limit the scope of this utility model.

[0009] Example 1, see Figure 1 A system for separating toluene from gaseous phosgene includes an absorption tower 1, a liquid toluene feed pipe 3 connected to the top of the absorption tower 1, and a phosgene inlet pipe 4 connected to the bottom of the absorption tower 1. The system is characterized in that: the gas phase outlet at the top of the absorption tower 1 is connected to an exhaust pipe 5, which is connected to a cyclone separator 2; the gas phase outlet at the top of the cyclone separator 2 is connected to a phosgene destruction system; the liquid phase outlet at the bottom of the absorption tower 1 is connected to an absorbent recovery pipe 6, which is connected to a desorption tower; the absorbent toluene is used to absorb uncondensed phosgene gas from the phosgene synthesis reaction entering the absorption tower 1; the unabsorbed phosgene is separated by the cyclone separator 2 and then enters the phosgene destruction system.

[0010] The liquid phase outlet at the bottom of the cyclone separator 2 is connected to the absorbent recovery pipe 6. The liquid toluene separated by the cyclone separator 2 is sent to the desorption tower to realize the recycling of toluene.

[0011] Working Process: In the phosgene synthesis reaction, chlorine and carbon monoxide react to produce phosgene, which is condensed into a liquid and sent to the downstream process for further reaction. Uncondensed phosgene gas enters absorber 1 through phosgene inlet pipe 4. Toluene is fed from the top of absorber 1 through toluene feed pipe 3 to absorb phosgene. The absorbed liquid is then sent from the bottom of absorber 1 to the toluene / phosgene desorption tower. Absorber 1 is connected to exhaust pipe 5 at the top. The liquid phase (containing toluene / phosgene-containing toluene) and gas phase (containing phosgene and tail gas from absorber 1) in exhaust pipe 5 are separated by cyclone separator 2. The liquid phase and the bottom liquid of absorber 1 are sent together through absorbent recovery pipe 6 to the toluene / phosgene desorption tower for toluene reuse; the gas phase is discharged to the phosgene destruction system.

Claims

1. A system for separating toluene from gaseous phosgene, comprising an absorption column (1), the absorption column (1) being connected to a liquid toluene feed pipe (3) at the top, and the absorption column (1) being connected to a phosgene feed pipe (4) at the bottom, characterized in that: The gas phase outlet at the top of the absorption tower (1) is connected to an exhaust pipe (5), which is connected to a cyclone separator (2). The gas phase outlet at the top of the cyclone separator (2) is connected to a phosgene destruction system. The liquid phase outlet at the bottom of the absorption tower (1) is connected to an absorbent recovery pipe (6), which is connected to a desorption tower.

2. A system for separating toluene from gaseous phosgene according to claim 1, characterized in that: The bottom liquid outlet of the cyclone separator (2) is connected to the absorbent recovery pipe (6). The liquid toluene separated by the cyclone separator (2) is sent to the desorption tower to realize the recycling of toluene.

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