Emptying low-pressure nitrogen recycling device

Abstract

The utility model discloses an emptying low-pressure nitrogen recycling device, which belongs to the technical field of emptying nitrogen recycling, and comprises an air separation device and an air separation precooling system, the air separation precooling system consists of a water cooling tower, an air cooling tower, a lithium bromide unit, a matched cooling water pump and a matched chilled water pump, dirty nitrogen generated by the air separation device enters the water cooling tower through a first pipeline, and surplus low-pressure nitrogen generated by the air separation device sequentially passes through a low-pressure nitrogen emptying valve and a second pipeline to enter the water cooling tower. The low-pressure emptying nitrogen is used as cooling gas of the air separation pre-cooling system, the load of a refrigerating unit of the pre-cooling system is reduced, the surplus low-pressure nitrogen is recycled, and the device is simple, easy to operate and low in cost.

Description

Technical Field

[0001] The utility model relates to the technical field of vented nitrogen recovery, in particular to a vented low-pressure nitrogen recovery and utilization device. Background Art

[0002] The main function of the air separation precooling system is to cool and wash the raw air, reduce the moisture in the air and economically and rationally utilize the polluted nitrogen produced by the air separation unit. The third and fourth phase precooling systems are composed of a water cooling tower, an air cooling tower, a lithium bromide unit and a matching cooling water pump and a refrigeration water pump. The production of refrigerated water is the initial cooling of desalted water in the water cooling tower, and then further cooling by the lithium bromide refrigeration unit to obtain 9.5℃ refrigerated water.

[0003] The working principle of the water cooling tower is: the flow of water and dirty nitrogen gas. Water and dirty nitrogen gas flow separately in the water cooling tower. The chilled water after heat exchange in the air cooling tower enters the top of the water cooling tower, and then after being distributed by the distributor, it forms a uniform mist water flowing downward in the water cooling tower. When the dirty nitrogen gas flows from bottom to top, the temperature of the water drops due to the heat exchange between water and dirty nitrogen gas, and the temperature decreases. In addition, due to the dry unsaturation of dirty nitrogen gas, some water molecules enter the dirty nitrogen gas molecules during the contact with chilled water, evaporating and absorbing heat, thereby reducing the temperature of the chilled water.

[0004] The design low pressure nitrogen volume of the air separation unit is 18500Nm 3 / h, in normal production, the gas consumption in the subsequent process is 12500Nm 3 / h to 16000Nm 3 / h, some of the surplus nitrogen will be discharged into the venting silencer through the low-pressure nitrogen vent valve, resulting in a waste of resources. There are two traditional methods for recycling low-pressure nitrogen: 1. Venting low-pressure nitrogen to liquefy, but this direction requires additional investment in new equipment, with high investment and low benefits; 2. Low-pressure nitrogen is used as sealing gas for the device. Since the sealing gas system of the air separation unit has been designed to be perfect and reasonable, this direction has little application prospect. Utility Model Content

[0005] In view of this, the utility model aims at the deficiencies of the prior art and provides a vented low-pressure nitrogen recovery and utilization device, which uses the low-pressure vented nitrogen as the cooling gas of the air separation precooling system to reduce the load of the refrigeration unit of the precooling system, not only realizing the recycling and utilization of surplus low-pressure nitrogen, but also the device is simple, easy to operate and low in cost.

[0006] In order to solve the above technical problems, the technical solution adopted by the utility model is: a vented low-pressure nitrogen recovery and utilization device, including an air separation device and an air separation precooling system, the air separation precooling system is composed of a water cooling tower, an air cooling tower, a lithium bromide unit and a matching cooling water pump and a refrigeration water pump. The dirty nitrogen generated by the air separation device enters the water cooling tower through a first pipeline, and the surplus low-pressure nitrogen generated by the air separation device enters the water cooling tower through a low-pressure nitrogen vent valve and a second pipeline in sequence.

[0007] Furthermore, the surplus low-pressure nitrogen produced by the air separation unit is 2500-6000 Nm 3 / h.

[0008] Furthermore, the surplus low-pressure nitrogen generated by the air separation unit has a dew point of less than -70°C and a temperature of 23 to 25°C.

[0009] Furthermore, a valve is arranged on the second pipeline.

[0010] Furthermore, the second pipeline is connected to the first pipeline via a three-way joint.

[0011] Furthermore, a circular hole is provided on a side surface of the first pipe, and the second pipe is welded to the circular hole.

[0012] Compared with the prior art, the beneficial effects of the utility model are as follows:

[0013] The utility model discloses a low-pressure nitrogen recovery and utilization device for venting, which allows the surplus low-pressure nitrogen generated by the air separation device to enter the water cooling tower through the low-pressure nitrogen vent valve and the second pipeline in sequence, and is used as cooling gas to achieve recovery and utilization, which can effectively reduce the load of the refrigeration unit of the precooling system, has low transformation cost, is safe and controllable, and has long-term economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of an embodiment of the utility model;

[0015] In the figure: 1-distillation tower, 2-water cooling tower, 3-first pipeline, 4-low-pressure nitrogen vent valve, 5-second pipeline, 6-valve, 7-three-way flange joint. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution of the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings of the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the described embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the utility model.

[0017] Example: Figure 1 As shown, a vented low-pressure nitrogen recovery and utilization device includes an air separation device and an air separation precooling system. The air separation device is a distillation tower 1, and the air separation precooling system consists of a water cooling tower 2, an air cooling tower, a lithium bromide unit and a matching cooling water pump and a refrigeration water pump. The dirty nitrogen generated by the air separation device enters the water cooling tower 2 through a first pipeline 3, and the surplus low-pressure nitrogen generated by the air separation device enters the water cooling tower 2 through a low-pressure nitrogen vent valve 4 and a second pipeline 5 in sequence.

[0018] The design low-pressure nitrogen volume of a plant's air separation unit is 18500Nm 3 / h, in normal production, the gas consumption in the subsequent process is 12500Nm 3 / h to 16000Nm 3 / h, so the surplus low-pressure nitrogen volume is 2500~6000Nm 3 / h, the dew point of surplus low-pressure nitrogen is less than -70℃, the temperature is 23~25℃, and it is a good cooling gas. The temperature of low-pressure nitrogen and dirty nitrogen is close, and the same dryness can achieve the same cooling effect.

[0019] A valve 6 is arranged on the second pipeline 5, and the second pipeline 5 is connected to the first pipeline 3 via a three-way flange joint 7, which can reduce the number of holes in the water cooling tower and reduce the difficulty of processing.

[0020] In other embodiments, a circular hole is opened on the side of the first pipe, and the second pipe is welded to the circular hole, so as to have good sealing performance.

[0021] The above is a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A low-pressure nitrogen recovery and utilization device, comprising an air separation device and an air separation precooling system, wherein the air separation precooling system is composed of a water cooling tower, an air cooling tower, a lithium bromide unit and a matching cooling water pump and a refrigeration water pump, and the dirty nitrogen generated by the air separation device enters the water cooling tower through a first pipeline, characterized in that: The surplus low-pressure nitrogen generated by the air separation device passes through the low-pressure nitrogen vent valve and the second pipeline in sequence and enters the water cooling tower.

2. The venting low-pressure nitrogen recovery and utilization device according to claim 1 is characterized in that: The surplus low-pressure nitrogen produced by the air separation unit is 2500-6000Nm 3 / h.

3. The venting low-pressure nitrogen recovery and utilization device according to claim 1 is characterized in that: The surplus low-pressure nitrogen generated by the air separation unit has a dew point of <-70°C and a temperature of 23-25°C.

4. The venting low-pressure nitrogen recovery and utilization device according to claim 1 is characterized in that: A valve is arranged on the second pipeline.

5. The venting low-pressure nitrogen recovery and utilization device according to claim 1 is characterized in that: The second pipeline is connected to the first pipeline through a three-way joint.

6. The venting low-pressure nitrogen recovery and utilization device according to claim 1, characterized in that: A circular hole is provided on the side of the first pipe, and the second pipe is welded to the circular hole.

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