Nitrogen generation and air compression system

Abstract

A nitrogen generation and air compression system comprises a nitrogen generation device and an air compression device, and the nitrogen generation device comprises an air compressor, a heat exchanger, a buffer tank, a precooling unit, a purifier, a fractionating tower and a rectifying tower which are sequentially arranged; the air compression device comprises a first filter, a drying cylinder, a second filter and a compressed air storage tank which are arranged in sequence; a first conveying pipeline is communicated between the drying cylinder and the air compressor, and a second conveying pipeline is communicated between the fractionating tower and the compressed air storage tank. According to the invention, the waste of recoverable gas in the nitrogen generation process can be reduced.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of industrial gas production and supply, and particularly relates to a nitrogen production and air compression system. BACKGROUND

[0002] In the chemical industry, nitrogen is an important protective gas, and its preparation and supply are crucial. At present, domestic industrial nitrogen production mainly adopts air separation technology. Common air separation nitrogen production methods include pressure swing adsorption (PSA), membrane separation and low-temperature separation. The PSA technology has relatively low cost, but the purity of the produced nitrogen is limited. The membrane separation technology can obtain high-purity nitrogen, but the equipment cost is high. The low-temperature separation technology can provide high-purity nitrogen, but the energy consumption is large. However, it is still a commonly used method for large-scale production of nitrogen.

[0003] At the same time, in industrial production, air compression systems are widely used in various pneumatic systems, especially in dry, oil-free and dust-free environments. A conventional air compression system mainly consists of an air compressor, an air tank, a drying device and the like, and is used to provide compressed air.

[0004] However, the air separation nitrogen production by low-temperature separation technology and the compressed air drying system have many problems in operation. On the one hand, the operation cost of air separation nitrogen production is high, and a large amount of recoverable gas is vented during the nitrogen production process, causing energy waste. On the other hand, the regeneration process of the compressed air drying system consumes a large amount of produced compressed air, further increasing the production cost. SUMMARY

[0005] The utility model provides a kind of nitrogen production and air compression system to solve the problems raised in the above background technology.

[0006] To solve the above technical problems, the technical scheme adopted by the utility model is as follows:

[0007] A nitrogen production and air compression system comprises:

[0008] A nitrogen production device comprising an air compressor, a heat exchanger, a buffer tank, a pre-cooling unit, a purifier, a fractionating column and a rectifying column arranged in sequence;

[0009] An air compression device comprising a first filter, a drying cylinder, a second filter and a compressed air tank arranged in sequence;

[0010] A first conveying pipeline is arranged in communication between the drying cylinder and the air compressor, and a second conveying pipeline is arranged in communication between the fractionating column and the compressed air tank.

[0011] Further, a pressure control valve is arranged on the second conveying pipeline and is controlled to open and close according to the gas pressure in the second conveying pipeline.

[0012] Further, the outlet end of the second conveying pipeline is simultaneously communicated with a plurality of conveying branch pipes, the compressed air storage tank comprises a plurality of gas storage sub-tanks, the plurality of conveying branch pipes are respectively and one-to-one communicated with the plurality of gas storage sub-tanks, and the gas storage dew point temperatures of the plurality of gas storage sub-tanks are different.

[0013] Further, a gas distribution joint is arranged between the second conveying pipeline and the plurality of conveying branch pipes, a dew point sensor is arranged on the gas distribution joint, and an on-off valve is arranged in each conveying branch pipe.

[0014] Further, a transfer gas storage cylinder is further arranged between the air compressor and the drying cylinder, the first conveying pipeline comprises a first section communicated between the transfer gas storage cylinder and the drying cylinder and a second section communicated between the transfer gas storage cylinder and the drying cylinder.

[0015] Further, a check valve is arranged on the first section, and a flow regulating valve is arranged on the second section.

[0016] Further, a third conveying pipeline is connected to the gas outlet end of the heat exchanger, and one end of the third conveying pipeline, away from the heat exchanger, is communicated with the transfer gas storage cylinder.

[0017] The utility model can achieve the following beneficial effects:

[0018] 1, the utility model discloses the large amount of air of nitrogen making device emptying is transported to the air compression device by first conveying pipeline and second conveying pipeline, effectively reduces energy waste, improves energy utilization rate, and simultaneously utilizes the oil-free oxygen-rich gas of nitrogen making device emptying to replace the regenerative gas consumed in the air compression device, reduces the amount of compressed air required for the regeneration of the air compression device, and improves the gas production efficiency of the air compression device.

[0019] 2, setting up the transfer gas storage cylinder can realize the temporary storage of the air of the nitrogen making device, when the compressed air pipe network demand is large, the load is high, the compressed air stored in the transfer gas storage cylinder can be used to supplement, the stability of system operation is enhanced, and the stable supply of the gas source is ensured.

[0020] 3, the utility model realizes the effective coupling of the nitrogen making device and the air compression device, reduces the equipment redundancy, and reduces the overall energy consumption and operation cost of the system. BRIEF DESCRIPTION OF DRAWINGS

[0021] The utility model will be further described below in combination with the drawings and examples:

[0022] Figure 1 It is the structure flow schematic view of the nitrogen making device of the utility model;

[0023] Figure 2The utility model discloses air compression device's structure flow schematic diagram.

[0024] In the drawings, the component list represented by each sign is as follows:

[0025] 1, nitrogen making device;11, air compressor;12, heat exchanger;13, buffer tank;14, precooling unit;15, purifier;16, fractionating column;17, rectifying column;18, condensation evaporator;19, turbine expander;2, air compression device;21, first filter;22, second filter;23, drying cylinder;231, first drying cylinder;232, second drying cylinder;24, gas storage sub-tank;3, first conveying pipeline;31, first section;32, second section;4, second conveying pipeline;41, conveying sub-pipe;5, gas distribution connector;6, transfer gas cylinder;7, third conveying pipeline;

[0026] 101, first valve;102, second valve;103, third valve;104, fourth valve;105, fifth valve;106, sixth valve;107, seventh valve;108, eighth valve;109, ninth valve;110, tenth valve;

[0027] 201, A vent valve;202, gas connection valve;203, B gas supply valve;204, A gas supply valve;205, B vent valve. DETAILED DESCRIPTION

[0028] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The drawings show embodiments of the present application. However, the present application can be implemented in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0029] As Figure 1 and Figure 2 shown, a nitrogen making and air compression system includes a nitrogen making device 1 and an air compression device 2. The nitrogen making device 1 includes an air compressor 11, a heat exchanger 12, a buffer tank 13, a precooling unit 14, a purifier 15, a fractionating column 16, a rectifying column 17, a condensation evaporator 18, and a turbine expander 19 arranged in sequence. The air compression device 2 includes a filter, a drying cylinder 23, and a compressed air storage tank arranged in sequence.

[0030] At the initial stage of the nitrogen making device 1, air is sucked into the air compressor 11 through the air filter, compressed, enters the heat exchanger 12, and then enters the buffer tank 13. At this time, the A vent valve 201, the air valve 202, and the B gas supply valve 203 are closed, and the A gas supply valve 204 and the B vent valve 205 are opened. The first conveying pipeline 3 is arranged between the B vent valve 205 and the air compression device 2, and the compressed gas that needs to be vented in the early stage is stored in the air compression device 2 through the first conveying pipeline 3.

[0031] Specifically, the air compressor 11 and the air compression device 2 are arranged with a transfer gas storage cylinder 6, the first conveying pipeline 3 includes a first section 31 connecting the transfer gas storage cylinder 6 and the buffer tank 13, and a second section 32 connecting the transfer gas storage cylinder 6 and the air compression device 2. The compressed gas that needs to be vented generated by the nitrogen making device 1 is first stored in the transfer gas storage cylinder 6 as regeneration gas for the drying cylinder 22. When the air compression device 2 needs regeneration gas to regenerate the adsorbent in the drying cylinder 22, the compressed gas stored in the transfer gas storage cylinder 6 can be discharged into the air compression device 2 through the second section 32 for use.

[0032] It should be noted that a check valve is arranged on the first section 31, and a flow regulating valve is arranged on the second section 32. The check valve controls the one-way flow of the compressed gas, and the flow regulating valve can accurately deliver the regeneration gas according to the regeneration demand of the drying cylinder 22 and the quality of the gas, thereby reducing resource waste while ensuring the regeneration effect.

[0033] When the nitrogen making device 1 is normally running, the A vent valve 201, the air valve 202, and the B vent valve 205 are closed, and the A gas supply valve 204 and the B gas supply valve 203 are opened. Then the gas passes through the pre-cooling unit 14, and the temperature of the compressed air is lowered to about 7℃ in the pre-cooling unit 14. After the free water is separated in the separator in the pre-cooling unit 14, the compressed air enters the purifier 15, and the water, carbon dioxide, and hydrocarbons such as acetylene in the air are removed by the molecular sieve adsorption in the purifier 15.

[0034] After the compressed air is purified, it enters the upper heat exchanger and the lower heat exchanger of the fractionating column 16 to exchange heat with the reflux low-temperature gas. The second conveying pipeline 4 is connected to the fractionating column 16, a pressure control valve is arranged on the second conveying pipeline 4, and the end of the second conveying pipeline 4 away from the fractionating column 16 is communicated with the air compression device 2. When the pressure in the second conveying pipeline 4 exceeds the set value, the pressure control valve is opened, and part of the gas enters the air compression device 2 to be stored.

[0035] Specifically, the outlet end of the second conveying pipeline 4 is provided with a gas distribution connector 5, the gas distribution connector 5 is communicated with a plurality of conveying sub-pipes 41, the compressed air storage tank includes a plurality of gas storage sub-tanks 23, the plurality of conveying sub-pipes 41 are respectively and correspondingly communicated with the plurality of gas storage sub-tanks 23, and the plurality of gas storage sub-tanks 23 are used for storing compressed gas with different dew point temperature intervals. A dew point sensor is arranged on each gas distribution connector 5, and an on-off valve is arranged in each conveying sub-pipe 41. The dew point temperature of the compressed gas in the second conveying pipeline 4 is detected through the dew point sensor, the on-off of the on-off valve in each conveying sub-pipe 41 is controlled according to the data monitored by the dew point sensor, and then the compressed gas with different dew point temperatures is stored in different gas storage sub-tanks 23; in one of the embodiments, when the dew point temperature of the compressed gas is ≤-40℃, the compressed gas enters a first gas storage sub-tank 23, and when the dew point temperature of the compressed gas is ≤-60℃, the compressed gas enters a second gas storage sub-tank 23.

[0036] The partially liquefied air after heat exchange between the compressed air and the reflux low-temperature gas in the upper heat exchanger and the lower heat exchanger of the fractionating tower 16 enters the rectifying tower 17. Most of the gas that is not liquefied rises to the top of the fractionating tower 16, part of which is condensed in the condenser evaporator 18 outside the fractionating tower 16, and the condensed liquid returns to the rectifying tower 17 as reflux liquid and is rectified with the rising gas. High-purity nitrogen gas is obtained at the top of the rectifying tower 17 and is reheated by the upper heat exchanger and the lower heat exchanger of the fractionating tower 16 and then is sent to the nitrogen buffer tank. Oxygen-rich liquid air is obtained at the bottom of the tower and is sent to the condenser evaporator 18 to condense nitrogen gas.

[0037] The vaporized oxygen-rich liquid air is reheated by the lower heat exchanger of the fractionating tower 16 and then enters the turbine expander 19 to expand and refrigerate, thereby supplementing the cold energy of the entire device. The expanded oxygen-rich air is reheated to room temperature by the lower heat exchanger and the upper heat exchanger of the fractionating tower 16, part of which is charged into the cold box as sealing gas of the nitrogen production device 1, so that the cold box maintains a certain positive pressure to prevent external water vapor from entering the cold box and causing the insulation material of the cold box to be dampened and the insulation effect to be reduced. Part of the air is sent to the purifier 15 for use in the regeneration of molecular sieves and is vented. Another part of the air is sent to the intermediate storage air cylinder 6 of the air compression device 2 for storage. Specifically, the outlet end of the heat exchanger 12 is connected with the intermediate storage air cylinder 6 through a third conveying pipeline 7 for air supply. In the later stage, the compressed gas stored in the intermediate storage air cylinder 6 is used as the regenerated gas in the drying cylinder 22, thereby reducing the consumption of compressed air for drying and regeneration of the compressed air system.

[0038] As Figure 2As shown, the filter includes a first filter 21 and a second filter 22, and the air compression device 2 further includes several valves, specifically, the regeneration step of the air compression device 2 is that the compressed air enters the drying cylinder 23 after passing through the first filter 21, the drying cylinder 23 includes a first drying cylinder 231 and a second drying cylinder 232, when the first drying cylinder 231 works and the second drying cylinder 232 regenerates, the first valve 101, the fourth valve 104, the sixth valve 106, the seventh valve 107 and the tenth valve 110 are opened; the second valve 102, the third valve 103, the fifth valve 105, the eighth valve 108 and the ninth valve 109 are closed, the compressed air enters the compressed air storage tank after passing through the second filter 22 after passing through the drying cylinder 23. When switching the working state, the first drying cylinder 231 regenerates and the second drying cylinder 232 works, the tenth valve 110 needs to be closed first, the ninth valve 109 is opened, the pressure in the second drying cylinder 232 is increased to the same as that in the first drying cylinder 231, and then the working state is switched. The first filter 21 and the second filter 22 are both connected with blowdown valves.

[0039] The design principle of the nitrogen production and air compression system is that: the low-temperature separation nitrogen production system will discharge waste gas during the nitrogen production process, the waste gas has low nitrogen content and low humidity, and can be used as the regeneration gas of the air compression device 2. Meanwhile, a large amount of compressed air is vented during the operation of the nitrogen production system, and the gas can be directly used for the air compression device 2, the compressed air at different stages is stored in different air storage tanks 23 of the air compression device 2, and the production cost of the air compression device 2 can be reduced.

[0040] The above only describes the preferred embodiments of the present application, and is not used to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A nitrogen and air compression system, characterized by, The application relates to a nitrogen production device. The device comprises an air compressor (11), a heat exchanger (12), a buffer tank (13), a pre-cooling unit (14), a purifier (15), a fractionating tower (16) and a rectifying tower (17) arranged in sequence. The device further comprises an air compression device (2) comprising a first filter (21), a drying cylinder (23), a second filter (22) and a compressed air storage tank arranged in sequence. A first conveying pipeline (3) is arranged between the drying cylinder (23) and the air compressor (11), and a second conveying pipeline (4) is arranged between the fractionating tower (16) and the compressed air storage tank.

2. A nitrogen generation and air compression system as claimed in claim 1, wherein: A pressure control valve is arranged on the second conveying pipeline (4) and is controlled to open or close according to the gas pressure in the second conveying pipeline (4).

3. A nitrogen generation and air compression system as claimed in claim 2, wherein: The outlet end of the second conveying pipeline (4) is connected to multiple conveying branch pipes (41), and the compressed air storage tank comprises multiple-stage air storage sub-tanks (24).

4. A nitrogen generation and air compression system as claimed in claim 3, wherein: Each of the multiple conveying branch pipes (41) is connected to one of the multiple-stage air storage sub-tanks (24), and the air storage dew point temperatures of the multiple-stage air storage sub-tanks (24) are different.

5. The nitrogen generation and air compression system of claim 1, wherein: A gas distribution joint (5) is arranged between the second conveying pipeline (4) and the multiple conveying branch pipes (41), and a dew point sensor is arranged on the gas distribution joint (5).

6. A nitrogen generation and air compression system as claimed in claim 5, wherein: An on-off valve is arranged in each of the conveying branch pipes (41).

7. A nitrogen generation and air compression system as claimed in claim 5, wherein: A transfer air storage cylinder (6) is further arranged between the air compressor (11) and the drying cylinder (23). The first conveying pipeline (3) comprises a first section (31) connecting the transfer air storage cylinder (6) and the drying cylinder (23), and a second section (32) connecting the transfer air storage cylinder (6) and the drying cylinder (23). A check valve is arranged on the first section (31), and a flow regulating valve is arranged on the second section (32). A third conveying pipeline (7) is connected to the outlet end of the heat exchanger (12), and one end of the third conveying pipeline (7) is connected to the transfer air storage cylinder (6).

Images