Treatment system for propylene-containing waste gas in process of producing epoxypropane by hydrogen peroxide

Abstract

The utility model discloses a system for treating propylene-containing waste gas in a process for producing epoxypropane by hydrogen peroxide, which is characterized by comprising an absorbent methanol buffer tank, a propylene absorption tower, a propylene-rich methanol buffer tank and a waste gas washing tower, a propylene-containing tail gas inlet and a nitrogen inlet are formed in the bottom of the propylene absorption tower, a tower top gas outlet of the propylene absorption tower is connected with a lower gas inlet of the waste gas washing tower, an industrial water inlet is formed in the upper part of the waste gas washing tower, and a tower bottom discharge hole of the propylene absorption tower is connected with the propylene-rich methanol buffer tank; materials in the propylene-rich methanol buffer tank return to a hydrogen peroxide production epoxypropane system through a second booster pump, tower top waste gas of the waste gas washing tower is discharged to the outside, a tower bottom waste water outlet of the waste gas washing tower is connected with a waste water buffer tank, and waste water in the waste water buffer tank is discharged to the outside through a third booster pump. The method has the advantages of simple operation, energy conservation, environmental protection and efficient treatment.

Description

Technical Field

[0001] The utility model relates to a waste gas treatment system in the chemical industry, in particular to a treatment system for waste gas containing propylene in a process of producing propylene oxide from hydrogen peroxide. Background Art

[0002] Propylene oxide (PO) is a downstream derivative of propylene with a production capacity second only to polypropylene. It is widely used in the production of many high value-added chemicals such as propylene glycol, propylene carbonate, polyurethane, unsaturated resin, etc., and plays an irreplaceable role in the fields of transportation electronics, construction furniture, daily chemicals and medicine. In recent years, with the continuous improvement of human living standards, the consumption of PO has shown an increasing trend year by year.

[0003] In patent CN1296128, propane is used to absorb propylene in the propylene oxide process to prevent the formation of an explosive mixture. The disadvantage is that propane does not participate in the epoxidation reaction, which increases the burden on the overall system. In patent CN103172486, the absorbent uses one or more mixtures of alcohol, diether alcohol and aldehyde to absorb propylene and propane, and after absorption, enters the analysis tower for analysis. The disadvantage is that analysis is required after absorption by the absorbent, which increases the energy consumption of the entire system and the complexity of the process. Summary of the invention

[0004] The technical problem to be solved by the utility model is to provide a treatment system for propylene-containing waste gas in the process of producing propylene oxide from hydrogen peroxide, which is simple to operate, energy-saving, environmentally friendly and highly efficient.

[0005] The utility model solves the above technical problems by adopting the following technical scheme: a treatment system for propylene-containing waste gas in a process of producing propylene oxide from hydrogen peroxide, comprising an absorbent methanol buffer tank, a propylene absorption tower, a propylene-rich methanol buffer tank and a waste gas washing tower, wherein the absorbent methanol buffer tank is connected to the top feed port of the propylene absorption tower through a first booster pump, a propylene-containing tail gas inlet and a nitrogen inlet are arranged at the bottom of the propylene absorption tower, a tower top gas outlet of the propylene absorption tower is connected to a lower gas inlet of the waste gas washing tower, an industrial water inlet is arranged at the top of the waste gas washing tower, a tower bottom discharge port of the propylene absorption tower is connected to the propylene-rich methanol buffer tank, and materials in the propylene-rich methanol buffer tank are returned to the hydrogen peroxide production propylene oxide system through a second booster pump.

[0006] Furthermore, the absorbent methanol buffer tank is provided with an absorbent methanol inlet, and the absorbent methanol includes fresh methanol and methanol from a methanol recovery unit.

[0007] Furthermore, the propylene-containing tail gas includes the propylene-containing tail gas from the propylene oxide reaction unit and the propylene-containing tail gas from the propylene recovery unit.

[0008] Furthermore, the exhaust gas from the top of the exhaust gas washing tower is discharged to the outside, the waste water outlet at the bottom of the exhaust gas washing tower is connected to the waste water buffer tank, and the waste water in the waste water buffer tank is discharged to the outside through the third booster pump.

[0009] Compared with the prior art, the utility model has the following advantages: the utility model is a treatment system for propylene-containing waste gas in the process of producing propylene oxide with hydrogen peroxide. The system uses methanol as an absorbent for propylene-rich waste gas in the process of producing propylene oxide with hydrogen peroxide, and the absorption is more efficient and energy-saving. The propylene-rich methanol does not need to be analyzed and is directly returned to the hydrogen peroxide production propylene oxide reaction system for reaction, which has the advantages of simple operation, energy saving and environmental protection. The tail gas absorbed by the propylene absorption tower also contains a small amount of organic matter such as alcohol and ether (mostly nitrogen), which is reabsorbed and washed with industrial water, and the exhaust gas can be directly discharged into the atmosphere to meet the corresponding environmental standards. The system can simply and efficiently treat the propylene-rich waste gas in the process of producing propylene oxide with hydrogen peroxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a structural schematic diagram of a treatment system for propylene-containing waste gas in a hydrogen peroxide production propylene oxide process according to the utility model, in which the labels are as follows: 1-absorbent methanol buffer tank, 2-first booster pump, 3-propylene absorption tower, 4-propylene-rich methanol buffer tank, 5-second booster pump, 6-waste gas washing tower, 7-wastewater buffer tank, 8-third booster pump. DETAILED DESCRIPTION

[0011] The present invention will be described in further detail below in conjunction with the accompanying drawings. Specific embodiments

[0013] A system for treating waste gas containing propylene in a process of producing propylene oxide from hydrogen peroxide, such as Figure 1 As shown, it includes an absorbent methanol buffer tank 1, a propylene absorption tower 3, a propylene-rich methanol buffer tank 4 and a waste gas washing tower 6. The absorbent methanol buffer tank 1 is connected to the top feed port of the propylene absorption tower 3 through a first booster pump 2. The bottom of the propylene absorption tower 3 is provided with a propylene-containing tail gas inlet and a nitrogen inlet. The top gas outlet of the propylene absorption tower 3 is connected to the lower gas inlet of the waste gas washing tower 6. The upper part of the waste gas washing tower 6 is provided with an industrial water inlet. The bottom discharge port of the propylene absorption tower 3 is connected to the propylene-rich methanol buffer tank 4. The material in the propylene-rich methanol buffer tank 4 is returned to the hydrogen peroxide production propylene oxide system through a second booster pump 5.

[0014] In this specific embodiment, an absorbent methanol inlet is provided on the absorbent methanol buffer tank 1, and the absorbent methanol includes fresh methanol and methanol from a methanol recovery unit. The propylene-containing tail gas includes the propylene-containing tail gas from a propylene oxide reaction unit and the propylene-containing tail gas from a propylene recovery unit. The top exhaust gas of the exhaust gas washing tower 6 is discharged to the outside, and the bottom wastewater outlet of the exhaust gas washing tower 6 is connected to the wastewater buffer tank 7, and the wastewater in the wastewater buffer tank 7 is discharged to the outside through the third booster pump 8.

[0015] The working process of the above processing system is as follows:

[0016] 1. The circulating methanol from the methanol recovery unit and the fresh methanol from outside the boundary first enter the absorbent methanol buffer tank 1 for buffering, and then enter the top of the propylene absorption tower 3 after being pressurized by the first booster pump 2;

[0017] 2. The tail gas containing propylene from the propylene oxide reaction unit and the propylene recovery unit and the nitrogen to prevent the formation of an explosive mixture enter the bottom of the propylene absorption tower 3. The pressure of the propylene absorption tower 3 is controlled to be 1.5-2.MPaG, the temperature is 35-40°C, and the number of theoretical plates is 15. The absorbent methanol and the tail gas rich in propylene are countercurrently absorbed. Propylene is gradually enriched from top to bottom along the propylene absorption tower 3. The waste gas obtained at the top of the propylene absorption tower 3 basically does not contain propylene. The absorption efficiency is 98.5%. The propylene-rich methanol obtained at the bottom of the tower is sent to the propylene-rich methanol buffer tank 4 and returned to the hydrogen peroxide production propylene oxide system through the second booster pump 5;

[0018] 3. The exhaust gas from the top of the propylene absorption tower 3 is sent to the bottom of the exhaust gas washing tower 6 for countercurrent washing with industrial water from outside the top of the tower. The pressure of the exhaust gas washing tower 6 is controlled to be 0.1-0.3MPaG, the temperature is 35-50°C, and the theoretical plate is 5. The wastewater containing organic matter such as alcohol and ether obtained at the bottom of the tower is sent to the wastewater buffer tank 7, and then sent to the outside of the boundary for treatment through the third booster pump 8. The tail gas obtained at the top of the tower has met the national emission requirements and can be directly discharged.

[0019] The above description is not intended to limit the present invention, and the present invention is not limited to the above examples. Any changes, modifications, additions or substitutions made by a person skilled in the art within the essential scope of the present invention shall also fall within the protection scope of the present invention.

Claims

1. A system for treating propylene-containing waste gas in a process for producing propylene oxide from hydrogen peroxide, characterized in that: The invention comprises an absorbent methanol buffer tank, a propylene absorption tower, a propylene-rich methanol buffer tank and a waste gas washing tower. The absorbent methanol buffer tank is connected with the top feed port of the propylene absorption tower through a first booster pump, a propylene-containing tail gas inlet and a nitrogen inlet are arranged at the bottom of the propylene absorption tower, a top gas outlet of the propylene absorption tower is connected with a lower gas inlet of the waste gas washing tower, an industrial water inlet is arranged at the top of the waste gas washing tower, a bottom discharge port of the propylene absorption tower is connected with the propylene-rich methanol buffer tank, and materials in the propylene-rich methanol buffer tank are returned to a hydrogen peroxide production propylene oxide system through a second booster pump.

2. The system for treating propylene-containing waste gas in a process for producing propylene oxide from hydrogen peroxide according to claim 1, characterized in that: The absorbent methanol buffer tank is provided with an absorbent methanol inlet, and the absorbent methanol includes fresh methanol and methanol from a methanol recovery unit.

3. The system for treating propylene-containing waste gas in a process for producing propylene oxide from hydrogen peroxide according to claim 1, characterized in that: The propylene-containing tail gas includes the propylene-containing tail gas from the propylene oxide reaction unit and the propylene-containing tail gas from the propylene recovery unit.

4. The system for treating propylene-containing waste gas in a process for producing propylene oxide from hydrogen peroxide according to claim 1, characterized in that: The exhaust gas at the top of the exhaust gas washing tower is discharged to the outside, the waste water outlet at the bottom of the exhaust gas washing tower is connected to the waste water buffer tank, and the waste water in the waste water buffer tank is discharged to the outside through the third booster pump.

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