Safety device for chemical ammonia evaporator

Abstract

The utility model belongs to the technical field of safety devices, and particularly relates to a safety device of a chemical ammonia evaporator. The safety device of the chemical ammonia evaporator comprises an ammonia superheater, a liquid ammonia evaporator and an ammonia recovery tank, a boundary ammonia feeding pipeline is arranged on the liquid ammonia evaporator, a root valve and a feeding valve are arranged on the boundary ammonia feeding pipeline, a gas outlet of the liquid ammonia evaporator is connected with the ammonia superheater, and a gas outlet of the ammonia recovery tank is connected with the ammonia recovery tank. A liquid outlet of the liquid ammonia evaporator is connected with the ammonia recovery tank, a gas phase outlet of the ammonia recovery tank is connected with the liquid ammonia evaporator, a safety valve bypass is arranged on the liquid ammonia evaporator, a discharge valve and a safety valve are arranged on the safety valve bypass, and one end of a heat source of the liquid ammonia evaporator is interlocked with a feed valve and is provided with a liquid level regulating valve. The chemical ammonia evaporator safety device provided by the utility model is applied to acrylonitrile reaction, is stable in operation and safe in operation, and saves materials.

Description

Technical Field

[0001] The utility model belongs to the technical field of safety devices, and in particular relates to a safety device for a chemical ammonia evaporator. Background Art

[0002] The production of acrylonitrile is mainly divided into three parts: the reaction part, the recovery part and the refining part. In the reaction part, ammonia is used to react with propylene. In industry, ammonia is generally reacted by on-site gasification of liquid ammonia, and the equipment used is a liquid ammonia evaporator.

[0003] Liquid ammonia evaporator is mainly used in pharmaceutical, chemical, metallurgical, food, textile and other industries, playing an important role of evaporation equipment. At the same time, in special occasions such as ships and airplanes, liquid ammonia evaporator is also used as air-conditioning equipment with good effect. The structure of ammonia evaporator is simple and the cost is low. The manufacturing, maintenance and installation of liquid ammonia evaporator are relatively easy. Therefore, compared with other equipment, the cost is lower. Liquid ammonia evaporator has high efficiency; as a heat exchange equipment, ammonia evaporator can achieve high-efficiency refrigeration effect due to the excellent performance of its working principle. Ammonia evaporator is corrosion-resistant and high-temperature resistant. The material of ammonia evaporator is good, with good corrosion resistance, high-temperature resistance and other characteristics, and it is durable.

[0004] However, when the liquid ammonia evaporator is used in the reaction of acrylonitrile, the conversion is unstable, the safety cannot be guaranteed, and the material waste is serious. Utility Model Content

[0005] The technical problem to be solved by the utility model is to overcome the above-mentioned defects in the prior art and provide a chemical ammonia evaporator safety device which is applied in the reaction of acrylonitrile and has stable operation, safe operation and material saving.

[0006] The chemical ammonia evaporator safety device of the utility model comprises an ammonia superheater, a liquid ammonia evaporator and an ammonia recovery tank. A boundary ammonia feed pipeline is arranged on the liquid ammonia evaporator, a root valve and a feed valve are arranged on the boundary ammonia feed pipeline, a gas outlet of the liquid ammonia evaporator is connected with the ammonia superheater, a liquid outlet of the liquid ammonia evaporator is connected with the ammonia recovery tank, a gas phase outlet of the ammonia recovery tank is connected with the liquid ammonia evaporator, a safety valve bypass is arranged on the liquid ammonia evaporator, a discharge valve and a safety valve are arranged on the safety valve bypass, one end of the heat source of the liquid ammonia evaporator is interlocked with the feed valve, and a liquid level regulating valve is arranged.

[0007] Preferably, a lean water outlet pipe and a lean water inlet pipe are provided at one end of the heat source of the liquid ammonia evaporator. The liquid level regulating valve is a liquid level regulating valve LIC-.

[0008] Preferably, the liquid outlet of the liquid ammonia evaporator is connected to the ammonia recovery tank via a sewage pipe.

[0009] Preferably, a low-pressure steam pipe b is provided on the ammonia recovery tank.

[0010] Preferably, a drain valve is provided at the bottom of the ammonia recovery tank.

[0011] Preferably, the drain valve is connected to the quench tower.

[0012] Preferably, the pipeline connecting the gas phase outlet of the ammonia recovery tank and the liquid ammonia evaporator is a gas phase recovery pipe.

[0013] Preferably, a pump is provided on the boundary ammonia feed pipeline.

[0014] Preferably, the gas outlet of the ammonia superheater is connected to the acrylonitrile reactor.

[0015] Preferably, the ammonia superheater is provided with a low-pressure steam pipe a and a condensate pipe.

[0016] The safety device for a chemical ammonia evaporator described in the utility model comprises the following steps when in operation:

[0017] 1. Liquid ammonia is led from the boundary area to the boundary area. The ammonia feed pipeline is introduced into the root valve through a pump. The feed valve is slowly opened to allow the liquid ammonia to be throttled and vaporized into the liquid ammonia evaporator. When the pressure of the liquid ammonia evaporator reaches 0.2MPa, the feed valve is closed and the discharge valve of the safety valve bypass is slowly opened to send the ammonia to the flare, so that the liquid ammonia is slowly vaporized and enters the liquid ammonia evaporator.

[0018] 2. When the pressure of the liquid ammonia evaporator reaches 0.05MPa, close the discharge valve, open the feed valve, introduce ammonia gas into the liquid ammonia evaporator to raise the pressure of the liquid ammonia evaporator to 0.2MPa before discharging. Repeat the above operation three times and then close the discharge valve.

[0019] 3. Fully open the root valve and use the liquid level regulating valve of the liquid ammonia evaporator to control the introduction of liquid ammonia. When the liquid level of the liquid ammonia evaporator reaches 70 (volume)%, close LIC-11001.

[0020] 4. Ammonia gas passing through the ammonia superheater enters the acrylonitrile reactor to participate in the reaction. After the acrylonitrile reactor starts to burn ammonia, the gaseous ammonia is heated to 66°C by the ammonia superheater and then enters the acrylonitrile reactor for combustion reaction. As ammonia continues to evaporate, the pressure of the liquid ammonia evaporator gradually decreases.

[0021] 5. When the pressure of the liquid ammonia evaporator drops to 0.25MPa, slowly feed the lean water (heating effect) obtained from the lean water inlet pipe into the liquid ammonia evaporator to ensure the heat required for ammonia gasification, so that the liquid ammonia in the liquid ammonia evaporator is continuously evaporated and gasified. Open the liquid ammonia feed valve of the liquid ammonia evaporator, and use the liquid level regulating valve to control the liquid level of the liquid ammonia evaporator at 40-70 (volume)%, and the pressure at 0.41-0.6MPa.

[0022] 6. A safety valve is installed on the top of the liquid ammonia evaporator. When the liquid ammonia evaporator equipment is over-pressured, the safety valve will trip and discharge to the flare system.

[0023] 7. A drain valve is provided at the bottom of the liquid ammonia evaporator, which is used for sewage replacement in the system during shutdown and maintenance. The sewage material is discharged to the ammonia recovery tank through a pipeline. The gas phase of the ammonia recovery tank is recovered to the liquid ammonia evaporator for reuse, and the liquid phase is treated for sewage and discharged to the quenching tower as wastewater treatment. At the same time, the ammonia recovery tank is provided with a low-pressure steam pipe b, which is used for replacement, cleaning and evaporation of the ammonia recovery tank.

[0024] Compared with the prior art, the utility model has the following beneficial effects:

[0025] The chemical ammonia evaporator safety device of the utility model realizes the conversion of liquid ammonia into gaseous ammonia in the application of an acrylonitrile reactor, realizes the stable operation of the ammonia evaporator, realizes the effective recovery of the materials involved in the ammonia evaporator, and realizes the safe discharge of gaseous ammonia. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the safety device of the chemical ammonia evaporator of the utility model.

[0027] In the figure: 1. ammonia superheater; 2. acrylonitrile reactor; 3. liquid ammonia evaporator; 4. ammonia recovery tank; 5. quenching tower; 6. low-pressure steam pipe a; 7. condensate pipe; 8. boundary ammonia feed pipeline; 9. pump; 10. safety valve bypass; 11. safety valve; 12. gas phase recovery pipe; 13. drain valve; 14. lean water outlet pipe; 15. lean water inlet pipe; 16. drain pipe; 17. low-pressure steam pipe b; 18. discharge valve; 19. root valve; 20. feed valve; 21. liquid level regulating valve. DETAILED DESCRIPTION

[0028] The utility model is further described below in conjunction with specific embodiments.

[0029] like Figure 1 As shown, the chemical ammonia evaporator safety device comprises an ammonia superheater 1, a liquid ammonia evaporator 3, and an ammonia recovery tank 4. The liquid ammonia evaporator 3 is provided with a boundary ammonia feed pipeline 8, and the boundary ammonia feed pipeline 8 is provided with a root valve 19 and a feed valve 20. The gas outlet of the liquid ammonia evaporator 3 is connected to the ammonia superheater 1, the liquid outlet of the liquid ammonia evaporator 3 is connected to the ammonia recovery tank 4, and the gas phase outlet of the ammonia recovery tank 4 is connected to the liquid ammonia evaporator 3. The liquid ammonia evaporator 3 is provided with a safety valve bypass 10, and the safety valve bypass 10 is provided with a discharge valve 18 and a safety valve 11. One end of the heat source of the liquid ammonia evaporator 3 is interlocked with the feed valve 20, and a liquid level regulating valve 21 is provided.

[0030] A lean water outlet pipe 14 and a lean water inlet pipe 15 are provided at one end of the heat source of the liquid ammonia evaporator 3. The liquid level regulating valve 21 is a liquid level regulating valve LIC-11001.

[0031] The liquid outlet of the liquid ammonia evaporator 3 is connected to the ammonia recovery tank 4 via a sewage pipe 16 .

[0032] A low-pressure steam pipe b17 is provided on the ammonia recovery tank 4.

[0033] A drain valve 13 is provided at the bottom of the ammonia recovery tank 4 .

[0034] The drain valve 13 is connected to the quench tower 5 .

[0035] The pipeline connecting the gas phase outlet of the ammonia recovery tank 4 and the liquid ammonia evaporator 3 is the gas phase recovery pipe 12.

[0036] A pump 9 is provided on the boundary ammonia feed pipeline 8 .

[0037] The gas outlet of the ammonia superheater 1 is connected to the acrylonitrile reactor 2 .

[0038] The ammonia superheater 1 is provided with a low-pressure steam pipe a6 and a condensate pipe 7.

[0039] The safety device for a chemical ammonia evaporator described in the utility model comprises the following steps when in operation:

[0040] 1. Liquid ammonia is led from the boundary area to the boundary area. The ammonia feed pipeline 8 is introduced into the rear root valve 19 through the pump 9. The feed valve 20 is slowly opened to throttle the liquid ammonia and gasify it into the liquid ammonia evaporator 3. When the pressure of the liquid ammonia evaporator 3 reaches 0.2MPa, the feed valve 20 is closed, and the discharge valve 18 of the safety valve bypass 10 is slowly opened to send the ammonia to the flare, so that the liquid ammonia is slowly gasified and enters the liquid ammonia evaporator 3.

[0041] 2. When the pressure of the liquid ammonia evaporator 3 reaches 0.05MPa, close the discharge valve 18, open the feed valve 20, introduce ammonia gas into the liquid ammonia evaporator 3 to raise the pressure of the liquid ammonia evaporator 3 to 0.2MPa before discharging. Repeat the above operation three times and then close the discharge valve 18.

[0042] 3. Fully open the root valve 19, and use the liquid level regulating valve 21 of the liquid ammonia evaporator 3 to control the introduction of liquid ammonia. When the liquid level of the liquid ammonia evaporator 3 reaches 70 (volume)%, close LIC-11001.

[0043] 4. Ammonia gas passing through ammonia superheater 1 enters acrylonitrile reactor 2 to participate in the reaction. After acrylonitrile reactor 2 starts burning ammonia, gaseous ammonia is heated to 66°C by ammonia superheater 1 and then enters acrylonitrile reactor 2 for combustion reaction. As ammonia continues to evaporate, the pressure of liquid ammonia evaporator 3 gradually decreases.

[0044] 5. When the pressure of the liquid ammonia evaporator 3 drops to 0.25 MPa, the lean water (heating effect) obtained through the lean water inlet pipe 15 is slowly fed into the liquid ammonia evaporator 3 to ensure the heat required for ammonia gasification, so that the liquid ammonia in the liquid ammonia evaporator 3 is continuously evaporated and gasified. The liquid ammonia feed valve 20 of the liquid ammonia evaporator 3 is opened, and the liquid level of the liquid ammonia evaporator 3 is controlled at 40-70 (volume)% by the liquid level regulating valve 21, and the pressure is controlled at 0.41-0.6 MPa.

[0045] 6. A safety valve 11 is provided on the top of the liquid ammonia evaporator 3. When the liquid ammonia evaporator 3 equipment is over-pressured, the safety valve 11 will trip and discharge to the flare system.

[0046] 7. A drain valve 13 is provided at the bottom of the liquid ammonia evaporator 3, which is used for sewage replacement in the system during shutdown and maintenance. The sewage material is discharged to the ammonia recovery tank 4 through a pipeline. The gas phase of the ammonia recovery tank 4 is recovered to the liquid ammonia evaporator 3 for reuse, and the liquid phase is treated for sewage and discharged to the quenching tower 5 as wastewater treatment. At the same time, the ammonia recovery tank 4 is provided with a low-pressure steam pipe b17, which is used for replacement, cleaning and evaporation of the ammonia recovery tank 4.

[0047] Of course, the above contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of the embodiments of the present invention. The present invention is not limited to the above examples, and any equivalent changes and improvements made by ordinary technicians in the technical field within the essential scope of the present invention shall fall within the scope of the patent coverage of the present invention.

Claims

1. A chemical ammonia evaporator safety device, characterized in that: The invention comprises an ammonia superheater (1), a liquid ammonia evaporator (3), and an ammonia recovery tank (4). The liquid ammonia evaporator (3) is provided with a boundary ammonia feed pipeline (8). The boundary ammonia feed pipeline (8) is provided with a root valve (19) and a feed valve (20). The gas outlet of the liquid ammonia evaporator (3) is connected to the ammonia superheater (1). The liquid outlet of the liquid ammonia evaporator (3) is connected to the ammonia recovery tank (4). The gas phase outlet of the ammonia recovery tank (4) is connected to the liquid ammonia evaporator (3). The liquid ammonia evaporator (3) is provided with a safety valve bypass (10). The safety valve bypass (10) is provided with a discharge valve (18) and a safety valve (11). One end of the heat source of the liquid ammonia evaporator (3) is interlocked with the feed valve (20) and is provided with a liquid level regulating valve (21).

2. The chemical ammonia evaporator safety device according to claim 1, characterized in that: A lean water outlet pipe (14) and a lean water inlet pipe (15) are provided at one end of the heat source of the liquid ammonia evaporator (3).

3. The chemical ammonia evaporator safety device according to claim 1 is characterized in that: The liquid outlet of the liquid ammonia evaporator (3) is connected to the ammonia recovery tank (4) via a sewage pipe (16).

4. The chemical ammonia evaporator safety device according to claim 1, characterized in that: A low-pressure steam pipe b (17) is provided on the ammonia recovery tank (4).

5. The chemical ammonia evaporator safety device according to claim 1 is characterized in that: A drain valve (13) is provided at the bottom of the ammonia recovery tank (4).

6. The safety device for a chemical ammonia evaporator according to claim 5, characterized in that: The drain valve (13) is connected to the quench tower (5).

7. The chemical ammonia evaporator safety device according to claim 1 is characterized in that: The pipeline connecting the gas phase outlet of the ammonia recovery tank (4) and the liquid ammonia evaporator (3) is a gas phase recovery pipe (12).

8. The chemical ammonia evaporator safety device according to claim 1, characterized in that: A pump (9) is provided on the critical zone ammonia feed pipeline (8).

9. The chemical ammonia evaporator safety device according to claim 1, characterized in that: The gas outlet of the ammonia superheater (1) is connected to the acrylonitrile reactor (2).

10. The chemical ammonia evaporator safety device according to claim 1, characterized in that: The ammonia superheater (1) is provided with a low-pressure steam pipe a (6) and a condensate pipe (7).

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