High-purity nitrogen production system

Abstract

The utility model discloses a high-purity nitrogen production system which comprises a gas inlet module, a rectifying tower, a first liquid nitrogen storage tank, a second liquid nitrogen storage tank and a return tank, the air inlet module is used for providing raw materials and cold energy into the rectifying tower; the liquid nitrogen outlet of the upper tower of the rectifying tower is connected with the inlet ends of the first liquid nitrogen storage tank and the second liquid nitrogen storage tank, the outlet ends of the first liquid nitrogen storage tank and the second liquid nitrogen storage tank are connected with the return tank, and the return tank is connected with the lower tower of the rectifying tower. The first liquid nitrogen storage tank and the second liquid nitrogen storage tank are used for guiding part of liquid nitrogen output by the upper tower of the rectifying tower into the lower tower of the rectifying tower so as to supplement cold energy for the lower tower to maintain operation of the lower tower, the liquid nitrogen storage tanks and the return tank are static equipment, shutdown and starting do not need too much operation, heating and cold blowing procedures are not needed, and the cost is reduced. Compared with the prior art, the starting time of the high-purity nitrogen production system is shortened, the production efficiency is improved, meanwhile, sealing gas does not need to be used, the situation that the product nitrogen is polluted after the sealing gas is cut off does not need to be worried about, and the cost for maintaining operation of equipment is further saved.

Description

Technical Field

[0001] The utility model belongs to the technical field of nitrogen preparation equipment, and specifically relates to a high-purity nitrogen production system. Background Art

[0002] Purity is an important technical parameter of nitrogen. According to the national standard, nitrogen purity is divided into three levels: industrial nitrogen, pure nitrogen and high-purity nitrogen. Their purities are 99.5% (O2≤0.5%), 99.99% (O2≤0.01%) and 99.999% (O2≤0.001%) respectively.

[0003] High-purity nitrogen is a widely used nitrogen. In the prior art, high-purity nitrogen is generally produced through air separation devices. In order to provide enough cooling capacity to the bottom of the tower, after the liquid nitrogen in the upper tower of the existing distillation tower is output, part of the liquid nitrogen will be pumped into the bottom of the distillation tower through a liquid nitrogen pump. The existing liquid nitrogen production system has the following problems when in use: a liquid nitrogen pump is used to establish liquid nitrogen interaction between the upper and lower towers to maintain the operation of high-purity nitrogen. The liquid nitrogen pump is a dynamic equipment. Every time it is shut down and pneumatically operated, it needs heating, cold blowing and other processes, and requires sealing gas. Once the sealing gas is cut off, outside air may enter the dynamic equipment, thereby causing pollution to the product nitrogen; or when shutting down and restarting, incomplete heating may cause damage to the liquid nitrogen pump; or incomplete cold blowing may cause the liquid nitrogen pump to fail to start. Utility Model Content

[0004] In order to solve the above problems existing in the prior art, the utility model aims to provide a high-purity nitrogen production system.

[0005] The technical solution adopted by the utility model is:

[0006] A high-purity nitrogen production system comprises an air intake module, a distillation tower, a first liquid nitrogen storage tank, a second liquid nitrogen storage tank and a reflux tank; the air intake module is used to provide raw materials and cold capacity to the distillation tower; the liquid nitrogen outlet of the upper tower of the distillation tower is connected to the inlet ends of the first liquid nitrogen storage tank and the second liquid nitrogen storage tank, the outlet ends of the first liquid nitrogen storage tank and the second liquid nitrogen storage tank are connected to the reflux tank, and the reflux tank is connected to the lower tower of the distillation tower.

[0007] Preferably, the reflux tank is a vacuum tank.

[0008] Preferably, the air intake module comprises an air compressor, a cold dryer, a purification system, a main heat exchanger and a cooling module which are connected in sequence, and the cooling module is connected to the lower tower of the distillation tower.

[0009] Preferably, the cooling module uses an expander.

[0010] Preferably, a cold-keeping box is provided outside the distillation tower, and the cold end of the expander and the main heat exchanger are both located in the cold-keeping box.

[0011] The beneficial effects of the utility model are:

[0012] The utility model provides a high-purity nitrogen production system, including an air intake module, a distillation tower, a first liquid nitrogen storage tank, a second liquid nitrogen storage tank and a reflux tank; the air intake module is used to provide raw materials and cold capacity to the distillation tower; the liquid nitrogen outlet of the upper tower of the distillation tower is connected to the inlet ends of the first liquid nitrogen storage tank and the second liquid nitrogen storage tank, the outlet ends of the first liquid nitrogen storage tank and the second liquid nitrogen storage tank are connected to the reflux tank, and the reflux tank is connected to the lower tower of the distillation tower. By using the first liquid nitrogen storage tank and the second liquid nitrogen storage tank, part of the liquid nitrogen output from the upper tower of the distillation tower is introduced into the lower tower of the distillation tower to supplement the cold capacity of the lower tower to maintain the operation of the lower tower. The liquid nitrogen storage tank and the reflux tank are both static equipment, and shutting down and starting up do not require excessive operations, and do not require heating and cold blowing processes, which reduces the startup time of the high-purity nitrogen production system and helps to improve production efficiency. At the same time, the utility model does not need to use sealing gas, and there is no need to worry about the pollution of product nitrogen after the sealing gas is cut off, and it also saves the cost of maintaining the operation of dynamic equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the process of the utility model.

[0014] In the figure: 1-air compressor, 2-cold dryer, 3-purification system, 4-main heat exchanger, 5-cooling module, 6-distillation tower, 7-first liquid nitrogen storage tank, 8-second liquid nitrogen storage tank, 9-reflux tank. DETAILED DESCRIPTION

[0015] In this embodiment, if Figure 1 A high-purity nitrogen production system is shown, which includes an air intake module, a distillation tower 6, a first liquid nitrogen storage tank 7, a second liquid nitrogen storage tank 8 and a reflux tank 9; the air intake module is used to provide raw materials and cold capacity to the distillation tower; the liquid nitrogen outlet of the upper tower of the distillation tower 6 is connected to the inlet ends of the first liquid nitrogen storage tank 7 and the second liquid nitrogen storage tank 8, and the outlet ends of the first liquid nitrogen storage tank 7 and the second liquid nitrogen storage tank 8 are connected to the reflux tank 9, and the reflux tank 9 is connected to the lower tower of the distillation tower 6. By using the first liquid nitrogen storage tank 7 and the second liquid nitrogen storage tank 8, part of the liquid nitrogen output from the upper tower of the distillation tower 6 is introduced into the lower tower of the distillation tower 6 to supplement the cold capacity of the lower tower to maintain the operation of the lower tower. The liquid nitrogen storage tank and the reflux tank 9 are both static equipment, and do not require excessive operations for shutting down and starting, and do not require heating and cold blowing processes, so they are more efficient to use. At the same time, the utility model does not need to use sealing gas, and there is no need to worry about the pollution of product nitrogen after the sealing gas is cut off, and the cost of maintaining the operation of dynamic equipment is also saved.

[0016] Specifically, the reflux tank 9 is a vacuum tank, which can extract liquid nitrogen from the first liquid nitrogen storage tank 7 and the second liquid nitrogen storage tank 8 through vacuum negative pressure.

[0017] Specifically, the air intake module includes an air compressor 1 , a cold dryer 2 , a purification system 3 , a main heat exchanger 4 and a cooling module 5 which are connected in sequence, and the cooling module 5 is connected to the lower tower of the distillation tower 6 .

[0018] In this embodiment, the cooling module 5 is an expander.

[0019] Based on the above design, the air intake module removes impurities from the raw gas, expands and refrigerates it, and then feeds it into the distillation tower 6, while providing the distillation tower 6 with raw materials and cooling capacity for gas nitrogen production; on the other hand, the air intake module and the distillation tower 3 form an existing air separation device. In other words, the high-purity nitrogen production system can effectively utilize existing equipment and reduce the cost of transformation. Furthermore, the connection relationship, working principle / process, etc. between the air intake module and the distillation tower 3 are clear and understandable to those skilled in the art.

[0020] During operation, air enters the air compressor 1, and the air compressor 1 and its terminal cooler compress and cool the air into 0.9Mpa, 42°C compressed air and send it to the cold dryer 2; the cold dryer 2 cools the compressed air to about 8°C and separates the moisture in the compressed air. After the impurities are removed, the compressed air is sent to the purification system 3. The purification system 3 adsorbs and purifies the impurities such as hydrocarbons and moisture in the compressed air to remove impurities from the compressed air again. The compressed air after impurity removal is sent to the main heat exchanger 4, and the compressed air enters the distillation tower 6 through the main heat exchanger 4 and the expander, providing cooling capacity for the distillation tower 6 to liquefy and separate the air and meet the cooling capacity required for nitrogen production.

[0021] In the present invention, a cold preservation box should be provided outside the distillation tower 6, and the cold end of the expander and the main heat exchanger 4 are both located in the cold preservation box. The cold preservation box or the refrigeration layer is a common cold preservation facility of the distillation tower 6, which will not be described in detail here.

[0022] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0024] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A high-purity nitrogen production system, characterized in that: It comprises an air intake module, a distillation tower (6), a first liquid nitrogen storage tank (7), a second liquid nitrogen storage tank (8) and a reflux tank (9); The air inlet module is used to provide raw materials and cold energy to the distillation tower; The liquid nitrogen outlet of the upper tower of the distillation tower (6) is connected to the inlet ends of the first liquid nitrogen storage tank (7) and the second liquid nitrogen storage tank (8), and the outlet ends of the first liquid nitrogen storage tank (7) and the second liquid nitrogen storage tank (8) are connected to a reflux tank (9), and the reflux tank (9) is connected to the lower tower of the distillation tower (6).

2. A high-purity nitrogen production system according to claim 1, characterized in that: The reflux tank (9) is a vacuum tank.

3. A high-purity nitrogen production system according to claim 1, characterized in that: The air intake module comprises an air compressor (1), a cold dryer (2), a purification system (3), a main heat exchanger (4) and a cooling module (5) which are connected in sequence, and the cooling module (5) is connected to the lower tower of the distillation tower (6).

4. A high-purity nitrogen production system according to claim 3, characterized in that: The cooling module (5) is an expander.

5. A high-purity nitrogen production system according to claim 4, characterized in that: The distillation tower (6) is provided with a cold-keeping box on its outer shell, and the cold end of the expander and the main heat exchanger (4) are both located in the cold-keeping box.

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