Waste gas utilization energy-saving device of PSA nitrogen making machine

Abstract

The invention relates to the field of nitrogen making machines, and discloses a PSA nitrogen making machine waste gas utilization energy-saving device which comprises a micro-heat regeneration adsorption type drying machine, an adsorption tower and a waste gas storage tank which are connected in sequence, and further comprises a gas return furnace and a gas separation valve, the gas return furnace is provided with an in-furnace space used for heating, a heating pipeline is laid along the outer side of the in-furnace space, and the gas separation valve is arranged on the outer side of the in-furnace space. The gas separation valve comprises a gas conveying cylinder as well as a large branch pipeline and a small branch pipeline which are connected to two opposite sides of the gas conveying cylinder, so that most of oxygen-enriched gas generated by the adsorption tower enters the in-furnace space of the gas return furnace along the large branch pipeline to assist the gas return furnace in heating; a small part of the eutrophic gas generated by the adsorption tower enters the micro-heat regeneration adsorption type drying machine through the small branch pipeline, and most of the eutrophic gas is used for combustion heating; and a small part of the heated eutrophic gas is used for performing micro-heat regeneration on the adsorption type drying machine so as to help an adsorbent of the micro-heat regeneration adsorption type drying machine to perform regeneration.

Description

Technical Field

[0001] The present invention relates to the field of nitrogen generators, and particularly to an energy-saving device for utilizing waste gas of a PSA nitrogen generator. Background Art

[0002] With the continuous advancement of the industrialization process, nitrogen, as a basic gas widely used in multiple industries such as chemistry, metallurgy, electronics, and food, has an increasing demand. The traditional nitrogen production method mainly uses pressure swing adsorption (PSA) technology.

[0003] In the pressure swing adsorption (PSA) nitrogen production technology, air, as the raw material gas, is first compressed and then enters the adsorption tower for the separation of the adsorbent and oxygen. In this process, the adsorption characteristics of the adsorbent play a key role in the high and low pressure exchange process. The gas output through the adsorption tower is used as the product gas. During the compression process, moisture will be compressed and exist in the form of water vapor. When this humid air enters the PSA system, the moisture has an adverse effect on the adsorbent (such as carbon molecular sieve). Water vapor will act on the adsorbent of the air adsorbent, reducing the adsorbent's adsorption of oxygen, and may also cause structural or deterioration problems of the adsorbent, thereby affecting its adsorption performance; Existing technologies mostly use micro-heat regeneration adsorption dryers to dry gases, but the adsorption dryers require regeneration gas consumption (6 - 12%), and in order to help the adsorbent of the micro-heat regeneration adsorption dryer to regenerate, the formed regeneration gas also needs to be heated. Therefore, an independent heating mechanism needs to be configured, which greatly increases the energy consumption of pressure swing adsorption nitrogen production; On the other hand, although PSA nitrogen generators have become common nitrogen production equipment in the industry, there is a relatively obvious problem in the existing nitrogen production technology, that is, during the separation process, the generated oxygen-rich gas (i.e., the gas rich in oxygen) is not fully utilized. In most cases, traditional PSA nitrogen generators directly discharge the oxygen-rich gas, resulting in waste of resources. The oxygen concentration of the oxygen-rich gas is usually above 90%, and it has certain industrial application value. Especially in industrial processes that require a relatively high oxygen concentration (such as gasification, incineration, oxy-fuel combustion, etc.), if these oxygen-rich gases can be reasonably utilized, it will greatly improve the energy utilization efficiency, reduce resource waste, and lower energy consumption; Therefore, how to cooperate with a micro-heat regeneration adsorption dryer to efficiently utilize these oxygen-rich gases is one of the difficult problems that need to be solved in the current PSA nitrogen production technology. Summary of the Invention

[0004] The purpose of the present invention is to provide an energy-saving device for utilizing waste gas of a PSA nitrogen generator to solve the above problems, and the specific technical solutions are as follows: PSA nitrogen generator waste gas utilization energy-saving device, including a micro-heat regenerative adsorption dryer, an adsorption tower and a waste gas storage tank connected in sequence, and also including a return air furnace and a gas separation valve. The return air furnace has a furnace inner space for heating, and a heating pipeline is laid along the outer side of the furnace inner space. The gas separation valve includes an air delivery cylinder and a large branch pipeline and a small branch pipeline connected to opposite sides of the air delivery cylinder. The large branch pipeline is communicated with the furnace inner space of the return air furnace. Two ends of the heating pipeline are respectively connected to the small branch pipeline and the micro-heat regenerative adsorption dryer. A return air pipeline is connected between the air delivery cylinder and the waste gas storage tank; An elastic end cover is arranged inside the air delivery cylinder, and the elastic end cover covers the inlets of the large branch pipeline and the small branch pipeline. The instantaneous discharge amount of the waste gas storage tank is greater than the sum of the instantaneous discharge amounts of the large branch pipeline and the small branch pipeline.

[0005] As an improvement of the above technical solution, the waste gas storage tank includes a first storage tank, a second storage tank and a negative pressure fan. The negative pressure fan is connected between the first storage tank and the second storage tank. The negative pressure fan is started intermittently. The return air pipeline is connected to the first storage tank, and the air delivery cylinder is connected to the second storage tank.

[0006] As an improvement of the above technical solution, the micro-heat regenerative adsorption dryer includes a first drying cylinder, a second drying cylinder, a total inlet pipe and a total outlet pipe. The first drying cylinder and the second drying cylinder are arranged side by side. The first drying cylinder and the second drying cylinder are respectively connected with a first inlet pipe and a second inlet pipe. The total inlet pipe is respectively connected with the first inlet pipe and the second inlet pipe. The first drying cylinder and the second drying cylinder are respectively connected with a first outlet pipe and a second outlet pipe. The total outlet pipe is respectively connected with the first outlet pipe and the second outlet pipe.

[0007] As an improvement of the above technical solution, a first adsorbent and a second adsorbent are respectively arranged inside the first drying cylinder and the second drying cylinder.

[0008] As an improvement of the above technical solution, the micro-heat regenerative adsorption dryer further includes a total return air pipe. The first drying cylinder and the second drying cylinder are respectively connected with a first return air pipe and a second return air pipe. The total return air pipe is respectively connected with the first return air pipe and the second return air pipe. The first return air pipe and the second return air pipe are respectively connected with a first valve and a second valve. The total return air pipe is connected to the small branch pipeline.

[0009] As an improvement of the above technical solution, it further includes a gas buffer tank. The gas buffer tank is respectively connected with the total outlet pipe and the adsorption tower.

[0010] As an improvement of the above technical solution, the adsorption tower is provided with a first nitrogen gas outlet and an exhaust gas outlet, and the exhaust gas outlet is connected to the return air pipeline.

[0011] As an improvement of the above technical solution, a regulating valve is connected to the main return air pipe.

[0012] As an improvement of the above technical solution, the elastic end cover includes a spring and a cover plate. The two ends of the spring are respectively connected to the cover plate and the bottom surface of the air delivery cylinder, and the thickness of the cover plate is greater than the width of the large branch pipe.

[0013] As an improvement of the above technical solution, a silica gel ring is sleeved outside the cover plate, and the silica gel ring is in interference fit with the inner wall of the air delivery cylinder.

[0014] The beneficial effects of the present invention: By setting the large branch pipe and the small branch pipe, most of the oxygen-rich gas generated by the adsorption tower enters the furnace space of the return air furnace along the large branch pipe to assist the return air furnace in heating, and a small part of the oxygen-rich gas generated by the adsorption tower enters the micro heat regeneration adsorption dryer through the small branch pipe. By adopting the above method, most of the oxygen-rich gas is used for combustion heating, and a small part of the heated oxygen-rich gas is used for the micro heat regeneration adsorption dryer to help the adsorbent of the micro heat regeneration adsorption dryer to be regenerated. That is, a small part of the oxygen-rich gas in the small branch pipe is used as the regeneration gas consumption required by the adsorption dryer. Arranging the small branch pipe along the outside of the heating pipe can improve the heat exchange efficiency and ensure the maximization of the utilization rate of the oxygen-rich gas; The thickness of the cover plate must be greater than the width of the large branch pipe to ensure that the cover plate can slide stably along the air delivery cylinder during the sliding process in the air delivery cylinder. By setting a silica gel ring on the cover plate, the sealing effect can be strengthened; By setting a gas buffer tank to store the dry gas, the dry gas can be continuously delivered to the adsorption tower, ensuring that the gas is not interrupted and improving the continuous operation ability of the system.

[0015] The additional aspects and advantages of the present invention will be partially given in the following description, partially will become obvious from the following description, or be understood through the practice of the present invention. Of course, it is not necessary for any product or method implementing the present application to achieve all the above-mentioned advantages simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 It is a schematic structural diagram of the present invention.

[0018] Figure 2 It is a schematic structural diagram of the elastic end cover of the present invention.

[0019] Figure 3 It is a schematic structural diagram of the gas return furnace of the present invention.

[0020] Figure 4 It is a schematic structural diagram of the cover plate of the present invention.

[0021] In the figure: micro heat regeneration adsorption dryer 1, adsorption tower 2, waste gas storage tank 3, gas return furnace 4, gas separation valve 5, large branch pipe 6, small branch pipe 7, negative pressure fan 8, gas buffer tank 9, first drying cylinder 11, second drying cylinder 12, first storage tank 31, second storage tank 32, gas transmission cylinder 51, cover plate 52, spring 53, silica gel ring 54. Specific embodiments

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] Before PSA nitrogen production, the raw material gas must be dried to reduce the influence of moisture on the adsorbent and improve the operation efficiency of the system. Common drying methods include refrigerated dryers and micro heat regeneration adsorption dryers 1. Among them, the micro heat regeneration adsorption dryer 1: uses molecular sieves and other highly efficient adsorbents. By adsorbing moisture in the air, the dew point of the treated gas can be reduced to -20°C to -30°C, which can effectively ensure the operation and long-term stability of the adsorbent. However, the regeneration process of the adsorption dryer requires a certain amount of energy and will increase the operation cost of the overall system. Based on the above, please refer to Figures 1 - 4 The present invention provides an energy-saving device for utilizing waste gas of a PSA nitrogen generator, including a micro heat regeneration adsorption dryer 1, an adsorption tower 2, and a waste gas storage tank 3 connected in sequence. The energy-saving device for utilizing waste gas of a PSA nitrogen generator further includes a gas return furnace 4 and a gas separation valve 5. The gas return furnace 4 has a furnace inner space for heating, and a heating pipe is laid along the outside of the furnace inner space. The gas separation valve 5 includes a gas transmission cylinder 51 and a large branch pipe 6 and a small branch pipe 7 connected to opposite sides of the gas transmission cylinder 51. The large branch pipe 6 is communicated with the furnace inner space of the gas return furnace 4. The two ends of the heating pipe are respectively connected to the small branch pipe 7 and the micro heat regeneration adsorption dryer 1. A gas return pipe is connected between the gas transmission cylinder 51 and the waste gas storage tank 3; Among them, the gas return furnace 4 is used to heat the regenerated gas. It can be understood that after the adsorption tower 2 generates nitrogen gas and oxygen-rich gas (or gas with a relatively high oxygen content), most of the oxygen-rich gas enters the furnace inner space of the gas return furnace 4 along the large branch pipeline 6 to assist the gas return furnace 4 in heating, while a small part of the oxygen-rich gas enters the micro-heat regenerative adsorption dryer 1 through the small branch pipeline 7. In this process, the gas return furnace 4 heats the oxygen-rich gas in the small branch pipeline 7. By using the above method, most of the oxygen-rich gas is used for combustion heating, and the heated small part of the oxygen-rich gas is used for the micro-heat regenerative adsorption dryer 1 to help the adsorbent of the micro-heat regenerative adsorption dryer 1 regenerate. That is, the small part of the oxygen-rich gas in the small branch pipeline 7 is used as the regeneration gas consumption required by the adsorption dryer. Preferably, arranging the small branch pipeline 7 along the outer side of the heating pipeline can improve the heat exchange efficiency.

[0024] To further optimize the distribution and utilization of oxygen-rich gas, an elastic end cover is provided inside the gas transmission cylinder 51. The function of this end cover is to dynamically adjust the distribution path of nitrogen gas according to the change of gas pressure, improve the utilization efficiency of oxygen-rich gas, and avoid energy waste. Specifically, an elastic end cover is provided inside the gas transmission cylinder 51. The elastic end cover covers the inlet of the large branch pipeline 6 and the inlet of the small branch pipeline 7. The instantaneous discharge amount of the waste gas storage tank 3 is greater than the sum of the instantaneous discharge amounts of the large branch pipeline 6 and the small branch pipeline 7. Specifically, after the waste gas storage tank 3 discharges oxygen-rich gas, the oxygen-rich gas will enter the gas transmission cylinder 51 along the gas return pipeline. In this embodiment, the amount of oxygen-rich gas discharged by the waste gas storage tank 3 per unit time should be able to form an extrusion on the elastic end cover. When the oxygen-rich gas in the gas transmission cylinder 51 reaches a certain level, when the waste gas storage tank 3 transports oxygen-rich gas into the gas transmission cylinder 51 again, under the action of air pressure, the elastic end cover is pushed or compressed, so that the elastic end cover instantly crosses the connection between the large branch pipeline 6 and the small branch pipeline 7 and the gas transmission cylinder 51 (or the inlet of the large branch pipeline 6 and the inlet of the small branch pipeline 7), which is equivalent to opening the inlet of the large branch pipeline 6 and the inlet of the small branch pipeline 7. At the same time, the oxygen-rich gas in the gas transmission cylinder 51 will enter the large branch pipeline 6 from the opened inlet of the large branch pipeline 6 and enter the small branch pipeline 7 from the inlet of the small branch pipeline 7; Regarding the design of the large branch pipeline 6 and the small branch pipeline 7, the micro heat regeneration adsorption dryer 1 usually only needs a small amount of dry air (about 5%) to enter the micro heat regeneration adsorption dryer 1 to cooperate with the desorption and regeneration of the adsorbent in the micro heat regeneration adsorption dryer 1 to restore the drying capacity of the adsorbent. Therefore, only the small branch pipeline 7 needs to be designed to meet the above requirements. For the return air furnace 4, a large amount of oxygen-rich gas is required to improve the heating efficiency. Therefore, the large branch pipeline 6 needs to be designed to meet the requirements. It should be noted that the micro heat regeneration adsorption dryer 1 combines the advantages of pressure swing adsorption and temperature swing adsorption, adsorbing (working) at normal temperature and high steam partial pressure; desorbing (regenerating) at a higher temperature and low steam partial pressure, that is, the moisture adsorbed by the adsorbent during the adsorption process is completely removed by the combined action of the thermal diffusion and low pressure of the regenerated gas (heated dry air) during the regeneration process. It has the advantages of high efficiency and low gas consumption, and there is a consumption of the regenerated gas during the regeneration process. Therefore, it is necessary to use the small branch pipeline 7 to transport a small part of the oxygen-rich gas for cooperation.

[0025] In order to effectively store and utilize the oxygen-rich gas, the present invention designs an exhaust gas storage tank 3, which includes a first storage tank 31, a second storage tank 32 and a negative pressure fan 8. The negative pressure fan 8 is connected between the first storage tank 31 and the second storage tank 32 of the exhaust gas storage tank. The first storage tank 31 is used to receive the oxygen-rich gas generated after the adsorption tower 2 operates. Its main function is to buffer the gas flow for a short time and collect the oxygen-rich gas at the same time. The negative pressure fan 8 starts intermittently. The return air pipeline is connected to the first storage tank 31, and the air delivery cylinder 51 is connected to the second storage tank 32. The negative pressure fan 8 operates intermittently. Its function is to adjust the flow direction of the oxygen-rich gas according to the gas pressure inside the storage tank and make the instantaneous discharge amount of the above exhaust gas storage tank 3 greater than the sum of the instantaneous discharge amounts of the large branch pipeline 6 and the small branch pipeline 7. Specifically, during the intermittent operation of the negative pressure fan 8, the oxygen-rich gas will gradually fill the second storage tank 32 and the air delivery cylinder 51. When the oxygen-rich gas in the second storage tank 32 and the air delivery cylinder 51 is saturated, when the negative pressure fan 8 is started again, the oxygen-rich gas entering the second storage tank 32 and the air delivery cylinder 51 can instantaneously push open the elastic end cover, and part of the oxygen-rich gas flows out from the large branch pipeline 6 and the small branch pipeline 7 to achieve pressure relief. After the pressure relief is completed, the elastic end cover resets, and the elastic end cover covers the inlet of the large branch pipeline 6 and the inlet of the small branch pipeline 7 again. The intermittent operation mode of the negative pressure fan 8 can also reduce energy consumption and is more energy-saving and environmentally friendly compared with a continuously operating system. Regarding the necessity of setting up the large branch pipeline 6 and the small branch pipeline 7, it is understandable that if the oxygen-rich gas in the large branch pipeline 6 is not used to assist the heating of the gas return furnace 4, for the gas return furnace 4 to heat the gas to meet the requirements, the gas return furnace 4 will inevitably consume more energy. Only by designing the large branch pipeline 6 and having the large branch pipeline 6 exactly transport the oxygen-rich gas that can be used for auxiliary heating can the above effects be achieved. Secondly, the gas transported by the small branch pipeline 7 may remain in the storage tank. Therefore, the gas transported by the small branch pipeline 7 cannot affect the subsequent operations; The elastic end cap cooperates with the large branch pipeline 6 and the small branch pipeline 7, enabling most of the oxygen-rich gas to enter the gas return furnace 4 through the large branch pipeline 6, while allowing a small part of the oxygen-rich gas to enter the micro heat regeneration adsorption dryer 1 through the small branch pipeline 7. The combustion assistance of most of the oxygen-rich gas entering the gas return furnace 4 acts on the small part of the oxygen-rich gas in the small branch pipeline 7, that is, heating the small part of the oxygen-rich gas in the small branch pipeline 7 to ensure the maximum utilization rate of the oxygen-rich gas. In this implementation, an elastic end cap is used instead of a traditional valve to ensure that the oxygen-rich gas in the gas transmission cylinder 51 has enough pressure to flow into the large branch pipeline 6 and the small branch pipeline 7 respectively after bursting open the elastic end cap. Coupled with the fact that the elastic end cap can automatically recover, it ensures that the gas volume input into the large branch pipeline 6 and the small branch pipeline 7 each time is at a relatively stable value, while ordinary valves are difficult to achieve the above effects or need to be equipped with other devices to achieve them.

[0026] Preferably, the elastic end cap includes a spring 53 and a cover plate 52. The two ends of the spring 53 are respectively connected to the cover plate 52 and the bottom surface of the gas transmission cylinder 51. The thickness of the cover plate 52 is greater than the width of the large branch pipeline 6. Generally, the thickness of the cover plate 52 is at least 1.5 times the width of the large branch pipeline 6. It is understandable that the thickness of the cover plate 52 must be greater than the width of the large branch pipeline 6 to ensure that during the sliding process of the cover plate 52 in the gas transmission cylinder 51, it will not be affected by the inlet of the large branch pipeline 6 and tilt and deviate from the movement path of the cover plate 52. A silica gel ring 54 is sleeved outside the cover plate 52, and the silica gel ring 54 is in interference fit with the inner wall of the gas transmission cylinder 51. By setting the silica gel ring 54, the sealing effect can be strengthened.

[0027] In some embodiments, a micro heat adsorption regeneration adsorption dryer is used to dry the gas entering the adsorption tower 2. The micro heat adsorption regeneration adsorption dryer ensures the continuous and stable operation of the system through the method of dual-cylinder alternating adsorption regeneration. At the same time, the regeneration efficiency is improved by optimizing the return gas path, reducing energy consumption. The micro heat regeneration adsorption dryer 1 includes a first drying cylinder 11, a second drying cylinder 12, a total inlet pipe and a total outlet pipe. The first drying cylinder 11 and the second drying cylinder 12 are arranged side by side and the first drying cylinder 11 and the second drying cylinder 12 perform drying operations alternately. The first drying cylinder 11 and the second drying cylinder 12 are respectively connected with a first inlet pipe and a second inlet pipe. The total inlet pipe is respectively connected with the first inlet pipe and the second inlet pipe. The first drying cylinder 11 and the second drying cylinder 12 are respectively connected with a first outlet pipe and a second outlet pipe. The total outlet pipe is respectively connected with the first outlet pipe and the second outlet pipe. The interiors of the first drying cylinder 11 and the second drying cylinder 12 are respectively provided with a first adsorbent and a second adsorbent. The micro heat regeneration adsorption dryer 1 further includes a total return pipe. The first drying cylinder 11 and the second drying cylinder 12 are respectively connected with a first return pipe and a second return pipe. The total return pipe is respectively connected with the first return pipe and the second return pipe. The first return pipe and the second return pipe are respectively connected with a first valve and a second valve. The total return pipe is connected to the small branch pipe 7; Operating principle: When the first drying cylinder 11 is in the adsorption working state, the compressed air enters the first inlet pipe through the total inlet pipe, flows through the first adsorbent, and the moisture is adsorbed by the adsorbent. Specifically, after the gas enters the first drying cylinder 11, it flows upward through the adsorbent, and the dried air is discharged from the upper part of the first drying cylinder 11. The dried air flows into the total outlet pipe through the first outlet pipe and is sent to the adsorption tower 2 through the pipeline; at the same time, the second drying cylinder 12 enters the regeneration state, and the adsorbed water is removed by the heating gas in the small branch pipe 7 to prepare for the next adsorption operation. Its regeneration process (releasing moisture and restoring adsorption capacity) is as follows: part of the dried air enters the total return pipe through the small branch pipe 7 and enters the drying cylinder being regenerated (for example, the second drying cylinder 12); After the regeneration is completed, the second drying cylinder 12 returns to the adsorption mode, and the first drying cylinder 11 switches to the regeneration mode. Preferably, a regulating valve is connected to the total return pipe for pressure reduction. By adopting the above-mentioned dual-drying-cylinder two-way operation, the continuity of the system is ensured. In addition, other related operating mechanisms of the micro heat adsorption regeneration adsorption dryer, such as the cooperation of each pipeline, valve and the drying cylinder, are well known to those skilled in the art and will not be elaborated here.

[0028] In some embodiments, the energy-saving device for waste gas utilization of the PSA nitrogen generator further includes a gas buffer tank 9. The gas buffer tank 9 is respectively connected to the main gas pipeline and the adsorption tower 2. During the adsorption stage of the first drying cylinder 11 or the second drying cylinder 12, the first drying cylinder 11 or the second drying cylinder 12 will transport the dried gas to the gas buffer tank 9. The gas buffer tank 9 receives the dried air from the main gas pipeline, stores part of the gas, and slowly and evenly transports it to the adsorption tower 2 to ensure the stable inhalation flow rate of the adsorption tower 2 and prevent the imbalance of the working state of the adsorbent caused by flow fluctuations. Secondly, when switching the working state of the first drying cylinder 11 or the second drying cylinder 12, since there is dried gas stored in the gas buffer tank 9, it can continuously transport the dried gas to the adsorption tower 2 to ensure that the gas is not interrupted and improve the continuous operation ability of the system.

[0029] In the present invention, the adsorption tower 2 is provided with a nitrogen gas outlet and an exhaust gas outlet. The exhaust gas outlet is connected to the return gas pipeline. The adsorption tower 2 is the core component of the entire device. The adsorption tower 2 is filled with carbon molecular sieve inside, and nitrogen gas is separated by the pressure swing adsorption principle (PSA). An oxygen gas outlet and an exhaust gas outlet are provided to discharge the separated nitrogen gas and oxygen-rich gas respectively.

[0030] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to include all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. PSA nitrogen generation waste gas utilization energy-saving device, comprising a micro-heat regeneration adsorption dryer, an adsorption tower and a waste gas storage tank connected in sequence, characterized in that, It also includes a gas return furnace and a gas separation valve. The gas return furnace has a furnace inner space for heating, and heating pipes are laid along the outer side of the furnace inner space. The gas separation valve includes an air delivery cylinder, a large branch pipe and a small branch pipe connected to opposite sides of the air delivery cylinder. The large branch pipe communicates with the furnace inner space of the gas return furnace. The two ends of the heating pipe are respectively connected to the small branch pipe and the micro heat regenerative adsorption dryer. A gas return pipe is connected between the air delivery cylinder and the waste gas storage tank; An elastic end cover is arranged inside the air delivery cylinder. The elastic end cover covers the inlets of the large branch pipe and the small branch pipe. The instantaneous discharge amount of the waste gas storage tank is greater than the sum of the instantaneous discharge amounts of the large branch pipe and the small branch pipe.

2. The PSA nitrogen generator waste gas utilization energy-saving device according to claim 1, characterized in that: The waste gas storage tank includes a first storage tank, a second storage tank and a negative pressure fan. The negative pressure fan is connected between the first storage tank and the second storage tank. The negative pressure fan starts intermittently. The gas return pipe is connected to the first storage tank, and the air delivery cylinder is connected to the second storage tank.

3. The PSA nitrogen generator waste gas utilization energy-saving device according to claim 2, characterized in that: The micro heat regenerative adsorption dryer includes a first drying cylinder, a second drying cylinder, a total inlet pipe and a total outlet pipe. The first drying cylinder and the second drying cylinder are arranged side by side. The first drying cylinder and the second drying cylinder are respectively connected with a first inlet pipe and a second inlet pipe. The total inlet pipe is respectively connected to the first inlet pipe and the second inlet pipe. The first drying cylinder and the second drying cylinder are respectively connected with a first outlet pipe and a second outlet pipe. The total outlet pipe is respectively connected to the first outlet pipe and the second outlet pipe.

4. The PSA nitrogen generator waste gas utilization energy-saving device according to claim 3, characterized in that: First adsorbents and second adsorbents are respectively arranged inside the first drying cylinder and the second drying cylinder.

5. The PSA nitrogen generation machine waste gas utilization energy-saving device according to claim 3, wherein: The micro heat regenerative adsorption dryer also includes a total return pipe. The first drying cylinder and the second drying cylinder are respectively connected with a first return pipe and a second return pipe. The total return pipe is respectively connected to the first return pipe and the second return pipe. The first return pipe and the second return pipe are respectively connected with a first valve and a second valve. The total return pipe is connected to the small branch pipe.

6. The PSA nitrogen generator waste gas utilization energy-saving device according to claim 3, characterized in that: It also includes a gas buffer tank. The gas buffer tank is respectively connected to the total outlet pipe and the adsorption tower.

7. The energy-saving device for waste gas utilization of the PSA nitrogen generator according to claim 1, characterized in that: The adsorption tower is provided with a first nitrogen gas outlet and a waste gas outlet. The waste gas outlet is connected to the gas return pipe.

8. The energy-saving device for PSA nitrogen generator waste gas utilization according to claim 5, characterized in that: A regulating valve is connected to the total return pipe.

9. The PSA nitrogen generator waste gas utilization energy-saving device according to claim 8, characterized in that: The elastic end cover includes a spring and a cover plate. The two ends of the spring are respectively connected to the cover plate and the bottom surface of the air delivery cylinder. The thickness of the cover plate is greater than the width of the large branch pipe.

10. The PSA nitrogen generator waste gas utilization energy-saving device according to claim 9, characterized in that: A silica gel ring is sleeved outside the cover plate. The silica gel ring is in interference fit with the inner wall of the air delivery cylinder.

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