A pressure swing adsorption oxygen production system and method for parallel sleeve-type adsorption towers with heterogeneous operation

Abstract

The present invention provides a pressure swing adsorption oxygen production system and method for heterogeneous operation of parallel sleeve-type adsorption towers, which is an improvement on the existing air separation oxygen production system. The space in the adsorption tower is divided into two adjacent and unconnected cylindrical spaces and annular spaces by using a metal cylindrical component. The adsorption materials in the cylindrical space and the annular space are subjected to heterogeneous adsorption and desorption operations respectively, and the heat released in the adsorption process is used for the heat required for desorption through heat exchange, thereby reducing the drastic change of the adsorption bed temperature due to the adsorption heat, effectively reducing the bed temperature in the adsorption stage, and effectively increasing the temperature of the adjacent bed in the desorption stage, thereby reducing the influence of temperature change on the adsorption capacity of the adsorption and desorption processes, thereby significantly improving the product gas recovery rate.

Description

Technical Field

[0001] The invention relates to the field of air separation, and in particular to a pressure swing adsorption oxygen production system and method for parallel sleeve-type adsorption towers operating in different phases. Background Art

[0002] Oxygen is the most commonly used industrial gas and is widely used in key industries such as steel, chemical industry and medical treatment. The main methods for producing oxygen by air separation include distillation, membrane separation and pressure swing adsorption (PSA). The distillation method uses the different boiling points of nitrogen and oxygen to achieve separation, which is suitable for large-scale production of high-purity oxygen, but has the disadvantage of complex system; the membrane separation method uses the difference in the permeation rate of oxygen and nitrogen on the membrane material to achieve oxygen production, which is suitable for small and medium-scale oxygen purity occasions. PSA uses the difference in the adsorption amount or rate of oxygen and nitrogen components on the adsorption material under different operating pressures to achieve oxygen production, and has the advantages of simple equipment and high purity. Therefore, in the field of small and medium-scale air separation oxygen production, PSA technology has been widely used.

[0003] As the requirements for high-quality economic development in my country continue to increase, energy conservation and emission reduction have become key requirements for the future development of the manufacturing industry. Reducing production energy consumption is the main way to achieve energy conservation and emission reduction, especially how to achieve efficient separation in oxygen production is a key basic issue. At present, the development of PSA oxygen production technology focuses on adsorption material modification, adsorption tower improvement, and oxygen production process optimization. In the case of a long and difficult research and development cycle for new adsorption materials, the optimization of the oxygen production process is particularly important.

[0004] There are typical pressure swing adsorption air separation oxygen production systems, such as Figure 3As shown, the air is compressed and pressurized by the compressor 1, and most of the impurities in the air are removed by the coarse filter 2. After cooling in the heat exchanger 3 (or refrigerated dryer), it enters the air buffer tank 4 and the precision filter 5. After multi-stage cooling and filtration, it becomes clean and dry air. By controlling the opening and closing of the electric or pneumatic valve, adsorption separation can be carried out in the two adsorption towers. The corresponding oxygen-rich product gas can be obtained at the top of the two adsorption towers, and the nitrogen-rich waste gas in the adsorption process is discharged at the air inlet end of the adsorption tower filled with adsorbent. The adsorption tower that completes adsorption and the adsorption tower that completes desorption can realize the two pressure equalization processes of the outlet end pressure equalization and the staggered pressure equalization of the outlet end and the air inlet end by controlling the opening and closing of the valve. In order to prevent the adsorption tower from penetrating prematurely, the pressure equalization time is very short, the useful components recovered are very limited, and the system energy consumption is high. At the same time, in the process of decompression and desorption of the adsorption tower that completes desorption, it is necessary to open the valve and the backwash valve to use part of the product gas for continuous backwashing and cleaning. Therefore, in the prior art, the recovery rate is greatly reduced due to the limitations of the pressure equalization and backwash cleaning steps and the temperature changes caused by the heat release in the adsorption process and the heat absorption in the desorption process. The system recovery rate is low, only about 35% to 45%, and the equipment energy consumption is very high.

[0005] The steps of pressurization, adsorption, equalization, decompression desorption and backwashing are the basic steps of the PSA oxygen production process. Among them, the equalization step is used to recover the useful mechanical energy and part of the oxygen in the oxygen production adsorption tower, and the backwashing is to use part of the oxygen-rich product gas as the cleaning gas in the desorption stage. Therefore, the effect of the equalization and backwashing steps directly affects the performance of the PSA oxygen production system. Domestic patent CN111282397B proposes to use multiple intermediate tanks to recover the gas in the tower after adsorption, decompose one equalization step into N equalization steps, increase the number of system equalization times, and improve the product gas recovery rate of the PSA oxygen production system, but the setting of multiple intermediate tanks increases the complexity of the system. Domestic patent CN104340961.A proposes a seven-valve two-step unequal potential equalization PSA oxygen production process that fully recovers tail gas, but in order to prevent the adsorption tower from penetrating in advance and obtaining high-concentration oxygen, the pressure in the two adsorption towers is not equal after the equalization is completed, and the useful components recovered are less, and the energy consumption of oxygen production is still high. U.S. Patent No. 8128734 proposed a method of completing the desorption tower by first reverse equalizing the pressure of the adsorption tower and then pressurizing the product oxygen to improve the oxygen production performance, but the number of equalization times is small and the recovery rate is limited. Domestic patent CN101531342.A proposed a five-tower PSA oxygen production process, which fully recovers the mechanical energy and useful components in the adsorption bed through multiple equalizations between adsorption towers, but its process is complicated. U.S. Patent No. 6454838 proposed a six-tower pressure swing adsorption oxygen production method with four outlet end equalizations, which effectively improved the oxygen recovery rate. However, the process is complicated and requires many components such as valves. Although steps such as product end equalization and alternating equalization can improve the product gas recovery rate of the PSA separation system, since the equalization pressure is closely related to the number of idle adsorption towers, the equalization step in the traditional double adsorption tower PSA system has limited improvement in the product gas recovery rate. Domestic patent CN101564636 proposes a method for improving oxygen recovery rate by intermittent backflushing, which can improve the product gas recovery rate of the PSA system, but the intermittent backflushing process requires complex valves and corresponding control systems. In summary, due to the limitations of traditional pressure equalization and backflushing steps, the recovery rate of the PSA air separation oxygen production system is low and the energy consumption is high. Summary of the invention

[0006] The technical problem to be solved by the present invention is: in order to overcome the shortcomings of the prior art, the present invention provides a pressure swing adsorption oxygen production system and method with parallel sleeve-type adsorption towers operating in a heterogeneous manner, improves the existing separation system, uses the heat released in the adsorption process for the heat required for desorption through heat exchange, reduces the drastic change in the adsorption bed temperature due to the adsorption heat, effectively reduces the bed temperature in the adsorption stage, and effectively increases the temperature of the adjacent bed in the desorption stage, reduces the influence of temperature changes on the adsorption capacity of the adsorption and desorption processes, and thus significantly improves the product gas recovery rate.

[0007] The technical solution adopted by the present invention to solve its technical problems is: a pressure swing adsorption oxygen production system with parallel sleeve-type adsorption towers operating in phase, comprising an air compressor, a coarse filter, a heat exchanger, an air buffer tank and a precision filter connected in sequence by pipelines, and also comprising an exhaust gas discharge pipeline, a product gas discharge pipeline and at least two adsorption towers, wherein the adsorption tower is provided with a cylindrical metal component, and the cylindrical metal component divides the space inside the adsorption tower into a cylindrical space and an annular space, and the annular space circumferentially surrounds the outside of the cylindrical space, and the cylindrical space of each adsorption tower and the corresponding annular space are not connected to each other; the cylindrical space of the adsorption tower has an inner air inlet at one axial end thereof and an inner air outlet at the other end thereof; the annular space of the adsorption tower has an outer air inlet at one axial end thereof and an outer air outlet at the other end thereof;

[0008] The inner air inlet is connected to the precision filter via an inner air inlet main pipeline, the outer air inlet is connected to the precision filter via an outer air inlet main pipeline, and the inner air inlet main pipeline and the outer air inlet main pipeline are respectively connected to the exhaust gas discharge pipeline;

[0009] The inner gas outlet is connected to an inner gas outlet main pipe, which is connected to the product gas discharge pipeline; the outer gas outlet is connected to an outer gas outlet main pipe, which is connected to the product gas discharge pipeline; the inner gas outlet main pipe and the outer gas outlet main pipe are both provided with a backwash control structure for respectively backwashing the inner gas outlet and the outer gas outlet;

[0010] The cylindrical space and the annular space in the adsorption tower are operated in phase and sequentially, and the gas flow direction has the following flow direction:

[0011] During the adsorption separation in the cylindrical space, the inner air inlet pipe, the cylindrical space, the inner air outlet pipe and the product gas discharge pipeline form a passage;

[0012] During the adsorption separation in the annular space, the external air inlet pipe, the annular space, the external air outlet pipe and the product gas discharge pipe form a passage;

[0013] When the annular space is depressurized for desorption, the annular space, the external air intake pipe and the exhaust gas discharge pipe form a passage;

[0014] When the cylindrical space is depressurized for desorption, a passage is formed between the cylindrical space, the inner air intake pipe and the exhaust gas discharge pipe;

[0015] When the cylindrical space is back-flushed and cleaned, the back-flushing control structure, the inner air outlet pipe, the cylindrical space, the inner air inlet pipe and the exhaust gas discharge pipe form a passage;

[0016] When the annular space is back-flushed and cleaned, the back-flushing control structure, the external air intake pipe, the annular space, the external air intake pipe and the exhaust gas discharge pipe form a passage;

[0017] When the cylindrical space and the annular space are pressure-equalized at the outlet end, the cylindrical space, the inner outlet main pipe, the outer outlet main pipe and the annular space form a passage;

[0018] When the cylindrical space and the annular space are pressure-equalized at the air intake end, a passage is formed between the cylindrical space, the inner air intake main pipe, the inner and outer air intake main pipes and the annular space.

[0019] Furthermore, each inner air inlet is connected to an inner air inlet branch pipe, and the inner air inlet branches of all adsorption towers are collected and connected to the inner air inlet main pipe; each outer air inlet is connected to an outer air inlet branch pipe, and the outer air inlet branches of all adsorption towers are collected and connected to the outer air inlet main pipe; each inner air outlet is connected to an inner air outlet branch pipe, and the inner air outlet branches of all adsorption towers are collected and connected to the inner air outlet main pipe; each outer air outlet is connected to an outer air branch pipe, and the outer air branch pipes of all adsorption towers are collected and connected to the outer air main pipe; the inner air inlet main pipe and the outer air inlet main pipe are both provided with valves for controlling the on-off of this section of the pipeline; the inner air outlet main pipe and the outer air outlet main pipe are also both provided with valves for controlling the on-off of this section of the pipeline.

[0020] Preferably, the waste gas discharge pipeline is provided with a waste gas discharge valve; and the product gas discharge pipeline is provided with a gas outlet control valve, an oxygen buffer tank and a pressure regulating valve in sequence.

[0021] Furthermore, the cylindrical space is filled with at least two layers of adsorption material with different particle diameters along the direction of the inner air inlet toward the inner air outlet, and the particle diameter of the adsorption material layer gradually increases along the direction of the inner air inlet toward the inner air outlet; the annular space is filled with at least two layers of adsorption material with different particle diameters along the direction of the outer air inlet toward the outer air outlet, and the particle diameter of the adsorption material layer gradually increases along the direction of the inner air inlet toward the inner air outlet.

[0022] Furthermore, the adsorption material layers in the same cylindrical space or the same annular space are separated by a perforated plate between two adjacent layers, and the perforated plate has a plurality of circular through holes; the outer end of the adsorption material layer located at the inner air outlet side end in the cylindrical space is compressed, and the outer end of the adsorption material layer located at the outer air outlet side end in the annular space is compressed.

[0023] A method for heterogeneous operation of parallel telescopic adsorption towers, using the above-mentioned pressure swing adsorption oxygen production system for heterogeneous operation of parallel telescopic adsorption towers, has the following cyclic operation steps:

[0024] A. The inner air intake pipe, cylindrical space, inner air outlet pipe and product gas discharge pipeline form a passage, and the cylindrical space is adsorbed and separated; at the same time, the annular space, the outer air intake pipe and the waste gas discharge pipeline form a passage, and the annular space is depressurized and desorbed;

[0025] B. The inner air inlet pipe, cylindrical space, inner air outlet pipe and product gas discharge pipeline form a passage, and the cylindrical space is adsorbed and separated; at the same time, the backflush control structure, the outer air outlet pipe, the annular space, the outer air inlet pipe and the waste gas discharge pipeline form a passage, and the annular space is backflush and cleaned;

[0026] C. The cylindrical space, the inner air outlet pipe, the outer air outlet pipe and the annular space form a passage, and the cylindrical space and the annular space are pressure-equalized at the air outlet end;

[0027] D. The cylindrical space, the inner air intake pipe, the inner and outer air intake pipes and the annular space form a passage, and the cylindrical space and the annular space are pressure-equalized at the air intake end;

[0028] E. The outer air intake pipe, the annular space, the outer air intake pipe and the product gas discharge pipeline form a passage, and the annular space is adsorbed and separated; at the same time, the cylindrical space, the inner air intake pipe and the waste gas discharge pipeline form a passage, and the cylindrical space is depressurized and desorbed;

[0029] F. The external air inlet pipe, the annular space, the external air outlet pipe and the product gas discharge pipeline form a passage, and the annular space is adsorbed and separated; at the same time, the backflush control structure, the internal air outlet pipe, the cylindrical space, the internal air inlet pipe and the waste gas discharge pipeline form a passage, and the cylindrical space is backflush and cleaned;

[0030] G. The cylindrical space, the inner air outlet pipe, the outer air outlet pipe and the annular space form a passage, and the cylindrical space and the annular space are pressure-equalized at the air outlet end;

[0031] H. The cylindrical space, the inner air intake pipe, the inner and outer air intake pipes and the annular space form a passage, and the cylindrical space and the annular space are pressure-equalized at the air intake end.

[0032] Preferably, the pressure equalization time at the air outlet of the cylindrical space and the annular space is 0.5 to 2 seconds, and the pressure equalization time at the air inlet of the cylindrical space and the annular space is 1 to 5 seconds.

[0033] The beneficial effect of the present invention is that the present invention provides a pressure swing adsorption oxygen production system and method with parallel telescopic adsorption towers operating in different phases. The pressure swing adsorption oxygen production system adopts a telescopic adsorption tower structure design, and the heat released in the adsorption process is used for the heat required for desorption through heat exchange, thereby reducing the drastic change of the adsorption bed temperature due to the adsorption heat and improving the stability of the device; at the same time, the influence of the adsorption bed temperature change on the adsorption capacity of the adsorption and desorption processes is reduced, thereby significantly improving the product gas recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0035] Figure 1 It is a structural schematic diagram of the best embodiment of the present invention.

[0036] Figure 2 It is a top view of the cross section of the adsorption tower in the best embodiment of the present invention.

[0037] Figure 3 It is a typical two-tower pressure swing adsorption air separation oxygen production system.

[0038] In the figure, 1, air compressor 2, coarse filter 3, heat exchanger 4, air buffer tank 5, precision filter 6, first valve 7, second valve 8, third valve 9, fourth valve 10, inner air intake main pipe 11, outer air intake main pipe 10A, first inner air intake branch pipe 10B, second inner air intake branch pipe 11A, first outer air intake branch pipe 11B, second outer air intake branch pipe 12, first adsorption tower 13, second adsorption tower 12a, first cylindrical metal component 13a, second cylindrical metal component 12A, first A cylindrical space 13A, a second cylindrical space 12B, a first annular space 13B, a second annular space 14, an inner gas outlet main pipe 15, an outer gas outlet main pipe 14A, a first inner gas outlet branch pipe 14B, a second inner gas outlet branch pipe 15A, a first outer gas outlet branch pipe 15B, a second outer gas outlet branch pipe 16, a fifth valve 17, a sixth valve 18, a seventh valve 19, an eighth valve 20, a ninth valve 21, a back-blowing control valve 22, a gas outlet control valve 23, an oxygen buffer tank 24, and a pressure regulating valve. DETAILED DESCRIPTION

[0039] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams that only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention, and directions and references (e.g., up, down, left, right, etc.) may only be used to help describe the features in the drawings. Therefore, the following specific embodiments are not to be taken in a limiting sense, and the scope of the subject matter claimed is limited only by the attached claims and their equivalents.

[0040] First, the meanings of some nouns in this application are as follows:

[0041] Adsorption materials, also known as adsorbents, refer to aluminosilicates or oxides with large specific surface, suitable pore and surface structure and strong adsorption capacity for nitrogen in the air;

[0042] Product gas, also known as product oxygen, refers to the component in the raw gas that is difficult to be adsorbed by the adsorbent. For example, for nitrogen adsorbent in air separation, oxygen is a component that is difficult to adsorb;

[0043] Waste gas refers to the component in the raw gas that is more easily adsorbed by the adsorbent. For example, for the nitrogen adsorbent in air separation, nitrogen is the component that is more easily adsorbed;

[0044] The adsorption tower may also be called adsorber, adsorption column, adsorption bed, and refers to a container filled with at least two layers of the above-mentioned adsorbent;

[0045] Unless otherwise specified, pressure refers to relative pressure (gauge pressure);

[0046] Pressure equalization refers to the process of connecting the outlet or inlet ends of two adsorption towers to balance the pressure in the two adsorption towers;

[0047] Pressure swing adsorption (PSA) refers not only to the PSA method, but also includes similar periodic pressure changes to utilize adsorbent adsorption separation methods, wherein the higher pressure during the periodic change process can be greater than or equal to atmospheric pressure, and the lower pressure can be less than or equal to atmospheric pressure, such as vacuum pressure swing adsorption and other methods.

[0048] like Figure 1 and Figure 2 The pressure swing adsorption oxygen production system with parallel sleeve-type adsorption towers operating in different phases is the best embodiment of the present invention.

[0049] The pressure swing adsorption oxygen production system includes an air compressor 1, a coarse filter 2, a heat exchanger 3, an air buffer tank 4, a precision filter 5, two adsorption towers filled with adsorption materials, an exhaust gas discharge pipeline and a product gas discharge pipeline. The two adsorption towers filled with adsorption materials are the first adsorption tower 12 and the second adsorption tower 13, respectively, and the oxygen and nitrogen separation is achieved by utilizing the different adsorption amounts or adsorption rates of oxygen and nitrogen components in the air on the adsorption materials under different operating conditions. An exhaust gas discharge valve is provided on the exhaust gas discharge pipeline. The product gas discharge pipeline is provided with an outlet control valve, an oxygen buffer tank and a pressure regulating valve in sequence.

[0050] Specifically, the adsorption tower is a cylindrical structure with a height-to-diameter ratio ranging from 0.3 to 10. The adsorption tower has a sleeve-shaped structure. A first cylindrical metal component 12a and a second cylindrical metal component 13a are respectively provided in the inner cavities of the two adsorption towers, and the inner space of the first adsorption tower 12 is divided into a first cylindrical space 12A and a first annular space 12B, and the inner space of the second adsorption tower 13 is divided into a second cylindrical space 13A and a second annular space 13B. The first cylindrical space 12A and the first annular space 12B are not connected to each other, and the second cylindrical space 13A and the second annular space 13B are not connected to each other.

[0051] The first cylindrical metal component 12a and the second cylindrical metal component 13a are made of metals such as copper with high thermal conductivity, and are used for heat exchange between the first cylindrical space 12A and the second cylindrical space 13A in the adsorption tower and the first annular space 12B and the second annular space 13B respectively. The diameter of the cylindrical metal component is about 1 / 2 to √3 / 2 of the diameter of the corresponding adsorption tower. Preferably, it is about √2 / 2 of the diameter of the corresponding adsorption tower.

[0052] The first adsorption tower 12 and the first adsorption tower 13 are filled with at least two layers of adsorption materials with different particle diameters in the first cylindrical space 12A and the second cylindrical space 13A and the first annular space 12B and the second annular space 13B along the axial direction. The first layer filled near the air inlet end of the adsorption tower is a pre-treatment adsorption material with a larger particle diameter (particle diameter of 0.5-4 mm), and the second layer filled near the air outlet end of the adsorption tower is a nitrogen adsorption material layer with a smaller particle diameter (particle diameter of 0.3-2.5 mm). The first pre-treatment adsorption material layer and the second nitrogen adsorption material layer are separated by a perforated plate with multiple circular through holes, and a spring, a ceramic ball or other pressing component or device is arranged at the top of the second nitrogen adsorption material layer.

[0053] The cylindrical spaces 12A and 13A near the air inlet end of the first adsorption tower 12 and the second adsorption tower 13 are connected to the inner air inlet main pipe 10 through the first inner air inlet branch pipe 10A and the second inner air inlet branch pipe 10B respectively, and the first annular space 12B and the second annular space 13B near the air inlet end are connected to the outer air inlet main pipe 11 through the first outer air inlet branch pipe 11A and the second outer air inlet branch pipe 11B, which are used for air intake, desorption and pressure equalization operations; the first cylindrical space 12A and the second cylindrical space 13A near the air outlet end are connected to the inner air outlet main pipe 14 through the first inner air outlet branch pipe 14A and the second inner air outlet branch pipe 14B, and the first annular space 12B and the second annular space 13B near the air outlet end are connected to the outer air outlet main pipe 15 through the first outer air outlet branch pipe 15A and the second outer air outlet branch pipe 15B, which are used for air outlet, backwash cleaning and pressure equalization operations.

[0054] The first cylindrical space 12A, the second cylindrical space 13A and the first annular space 12B, the second annular space 13B are connected through the inner intake main pipe 10, the outer intake main pipe 11, the first inner intake branch pipe 10A, the second inner intake branch pipe 10B, the first outer intake branch pipe 11A, the second outer intake branch pipe 11B, for pressure equalization at the intake end. A third valve 8 is provided on the pipeline between the inner intake main pipe 10 and the first cylindrical space 12A, the second cylindrical space 13A; a fourth valve 9 is provided on the pipeline between the outer intake main pipe 11 and the first annular space 12B, the second annular space 13B; the pipeline between the third valve 9 and the fourth valve 9 is connected, and the pipeline is connected to the exhaust gas discharge pipeline.

[0055] The first cylindrical space 12A, the second cylindrical space 13A, the first annular space 12B, and the second annular space 13B are connected through the inner gas outlet main pipe 14, the outer gas outlet main pipe 15, the first inner gas outlet branch pipe 14A, the second inner gas outlet branch pipe 14B, the first outer gas outlet branch pipe 15A, and the second outer gas outlet branch pipe 15B for pressure equalization at the gas outlet end. The inner gas outlet main pipe 14 is connected to the outer gas outlet main pipe 15 by a pipeline, and a fifth valve 16 and a sixth valve 17 are respectively provided on the pipeline.

[0056] The first cylindrical space 12A, the second cylindrical space 13A, the first annular space 12B, and the second annular space 13B are connected to each other through the inner gas outlet main pipe 14, the outer gas outlet main pipe 15, the first inner gas outlet branch pipe 14A, the second inner gas outlet branch pipe 14B, the first outer gas outlet branch pipe 15A, and the second outer gas outlet branch pipe 15B for backwashing. The inner gas outlet main pipe 14 and the outer gas outlet main pipe 15 are connected by a pipeline, and a seventh valve 18 and a backwashing control valve structure are respectively provided on the pipeline. The backwashing control structure is preferably a backwashing control valve 21, and the opening of the backwashing control valve is adjustable.

[0057] The air inlet ends of the first adsorption tower 12 and the second adsorption tower 13 are connected to the air inlet through the necessary first inner air inlet branch pipe 10A and second inner air inlet branch pipe 10B, the inner air inlet main pipe 10, the first outer air inlet branch pipe 11A and second outer air inlet branch pipe 11B, and the outer air inlet main pipe 11. The inner air inlet main pipe 10 is provided with a first valve 6, the outer air inlet main pipe 11 is provided with a first valve 7, and the first valve 6 and the second valve 7 are connected to the pipeline, which is externally connected to the air outlet end of the precision filter 5 at the front end to complete the air intake of the adsorption tower air inlet end.

[0058] The gas outlet ends of the first adsorption tower 12 and the second adsorption tower 13 are connected to the outside and connected to the product gas discharge pipeline through the first inner gas outlet branch pipe 14A, the second inner gas outlet branch pipe 14B, the inner gas outlet main pipe 14, the first outer gas outlet branch pipe 15A, the second outer gas outlet branch pipe 15B, and the outer gas outlet main pipe to discharge gas. Among them, the inner gas outlet main pipe 14 is provided with an eighth valve 19, and the outer gas outlet main pipe 15 is provided with a ninth valve 20. The eighth valve 19 and the ninth valve 20 are connected by a pipeline, and the pipeline is connected and connected to the product gas discharge pipeline to discharge gas.

[0059] The above-mentioned pressure swing adsorption oxygen production system has the following operating steps:

[0060] After the air compressor 1 pressurizes and heats the raw air, the high-pressure and high-temperature raw air passes through the coarse filter 2 to remove most of the impurities, moisture and other substances, and then cools down through the heat exchanger 3, and enters the air buffer tank 4 and the precision filter 5, and further filters most of the oil, moisture and other impurities in the air in the precision filter 5. The first valve 6 is opened to introduce the high-pressure air into the first cylindrical space 12A and the second cylindrical space 13A of the first adsorption tower 12 and the second adsorption tower 13 through the inner air intake main pipe 10 and the first inner air intake branch pipe 10A and the second inner air intake branch pipe 10B respectively for adsorption separation, wherein most of the nitrogen in the air is adsorbed by the adsorption materials in the first cylindrical space 12A and the second cylindrical space 13A, and the product gas containing high concentration of oxygen is obtained at the top. At the same time, the fourth valve 9 and the exhaust gas discharge valve 25 are opened to connect the first annular space 12B and the second annular space 13B of the first adsorption tower 12 and the second adsorption tower 13 through the external air intake main pipe 11 and the first external air intake branch pipe 11A and the second external air intake branch pipe 11B to the atmospheric environment for pressure reduction and desorption. Preferably, during the process of pressure reduction and desorption, the seventh valve 18 and the backwash control valve 21 can be opened at the same time to introduce part of the product gas from the first cylindrical space 12A and the second cylindrical space 13A into the corresponding first annular space 12B and the second annular space 13B for backwash cleaning, thereby improving the regeneration effect of the adsorption material. As the adsorption and desorption proceed, the adsorption material in the first cylindrical space 12A and the second cylindrical space 13A in the first adsorption tower 12 and the second adsorption tower 13 is saturated, and the adsorption material in the first annular space 12B and the second annular space 13B is completely desorbed. At this time, close the first valve 6, the fourth valve 9, the seventh valve 18, the blowback control valve 21 and the exhaust gas discharge valve 25, open the fifth valve 16 and the sixth valve 17 to connect the outlet ends of the first cylindrical space 12A and the second cylindrical space 13A with the first annular space 12B and the second annular space 13B through necessary pipelines to balance the pressure at the outlet end, then close the fifth valve 16 and the sixth valve 17, and open the third valve 8 and the fourth valve 9 at the same time to connect the inlet ends of the first cylindrical space 12A, the second cylindrical space 13A and the first annular space 12B and the second annular space 13B through necessary pipelines to balance the pressure at the inlet end. Preferably, the duration of the pressure balance at the outlet end is short, about 0.5 to 2 seconds, and the duration of the pressure balance at the inlet end is long, about 1 to 5 seconds.After completing the pressure equalization at the air inlet end, the adsorbent material in the first cylindrical space 12A and the second cylindrical space 13A in the first adsorption tower 12 and the second adsorption tower 13 is reversely depressurized and desorbed by opening the third valve 8 and the exhaust gas discharge valve 25. At the same time, the second valve 7 is opened to introduce high-pressure air into the first annular space 12B and the second annular space 13B in the first adsorption tower 12 and the second adsorption tower 13 through necessary pipelines for adsorption and separation. After that, the first annular space 12B and the second annular space 13B and the first cylindrical space 12A and the second cylindrical space 13A complete the pressure equalization at the air outlet end and the air inlet end in turn, thereby completing a cycle process.

[0061] Specifically, each automatic switching valve is switched according to the requirements of the following table, and the first cylindrical space 12A and the second cylindrical space 13A and the first annular space 12B and the second annular space 13B in the first adsorption tower 11 and the second adsorption tower 12 are operated in phase sequence, and the operation steps are shown in the following table:

[0062]

[0063]

[0064]

[0065] This embodiment adopts a pressure swing adsorption oxygen production system with two parallel sleeve-type adsorption towers operated in different phases to improve the recovery rate. The exhaust pressure of the air compressor is 0.7 MPa, the exhaust temperature is about 60°C, and the adsorption pressure is 0.55 MPa.

[0066] Taking the case where the cylindrical space bed layer in the first adsorption tower 12 and the second adsorption tower 13 is in the adsorption stage, while the annular space bed layer in the two adsorption towers is in the desorption stage as an example, the high-pressure and high-temperature air passes through the coarse filter 2 and the refrigerated dryer 3 to remove most of the impurities, moisture and other substances and enters the air buffer tank 4 and the precision filter 5 after cooling. After most of the oil, moisture and other impurities in the air are further filtered out in the precision filter 5, the first valve 6 is opened to introduce the high-pressure air into the two cylindrical spaces for adsorption and separation. The heat generated during the adsorption process is transferred to the two annular spaces through two cylindrical metal components. After heat exchange, the bed temperature in the two cylindrical spaces is reduced from 45°C to about 37°C, while the bed temperature in the two annular spaces is increased from 28°C to 34°C, which effectively suppresses the drastic temperature changes during the adsorption and desorption processes, reduces the adverse effects of temperature changes on the capacity of the adsorption process, and improves the product gas recovery rate. After the cylindrical space beds in the two adsorption towers complete adsorption, the fifth valve 16 and the sixth valve 17 are opened to equalize the pressure at the gas outlet with the two annular space beds that have completed desorption through necessary pipelines. The pressure of the two cylindrical space beds is reduced from 0.55Mpa to about 0.4MPa, and the gas pressure of the two annular space beds is increased from 0.1Mpa to about 0.2MPa. Then, the third valve 8 and the fourth valve 9 are opened to connect the air inlet ends of the two cylindrical space beds with the air inlet ends of the two annular space beds through necessary pipelines to equalize the pressure at the air inlet end. The gas pressure of the two cylindrical space beds is further reduced from 0.4Mpa to about 0.3MPa, and the gas pressure of the two annular space beds is increased from 0.2Mpa to about 0.28MPa. After the pressure equalization at the inlet end is completed, the two cylindrical space beds are reversely depressurized and desorbed by opening the third valve 8 and the exhaust gas discharge valve, and at the same time, the second valve 7 is opened to introduce high-pressure air into the two annular space beds through necessary pipelines for adsorption, and then the pressure equalization at the outlet end and the pressure equalization at the inlet end are similarly performed to complete a cycle process. After this cycle process, the recovery rate of the product gas is at least 55%, which is more than 10% higher than the product gas recovery rate of the existing typical pressure swing adsorption air separation oxygen production system, and the separation energy consumption is reduced by at least 20%.

[0067] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A pressure swing adsorption oxygen production system with parallel telescopic adsorption towers operating in different phases, comprising an air compressor, a coarse filter, a heat exchanger, an air buffer tank and a precision filter connected in sequence by pipelines, characterized in that: It also includes a waste gas discharge pipeline, a product gas discharge pipeline and at least two adsorption towers, wherein a cylindrical metal component is provided in the adsorption tower, and the cylindrical metal component divides the space in the adsorption tower into a cylindrical space and an annular space, wherein the annular space circumferentially surrounds the cylindrical space, and the cylindrical space of each adsorption tower and the annular space corresponding thereto are not connected to each other; the cylindrical space of the adsorption tower has an inner air inlet at one axial end thereof and an inner air outlet at the other end thereof; the annular space of the adsorption tower has an outer air inlet at one axial end thereof and an outer air outlet at the other end thereof; The inner air inlet is connected to the precision filter via an inner air inlet main pipeline, the outer air inlet is connected to the precision filter via an outer air inlet main pipeline, and the inner air inlet main pipeline and the outer air inlet main pipeline are respectively connected to the exhaust gas discharge pipeline; The inner gas outlet is connected to an inner gas outlet main pipe, which is connected to the product gas discharge pipeline; the outer gas outlet is connected to an outer gas outlet main pipe, which is connected to the product gas discharge pipeline; the inner gas outlet main pipe and the outer gas outlet main pipe are both provided with a backwash control structure for respectively backwashing the inner gas outlet and the outer gas outlet; The cylindrical space and the annular space in the adsorption tower are operated in phase and sequentially, and the gas flow direction has the following flow direction: During the adsorption separation in the cylindrical space, the inner air inlet pipe, the cylindrical space, the inner air outlet pipe and the product gas discharge pipeline form a passage; During the adsorption separation in the annular space, the external air inlet pipe, the annular space, the external air outlet pipe and the product gas discharge pipe form a passage; When the annular space is depressurized for desorption, the annular space, the external air intake pipe and the exhaust gas discharge pipe form a passage; When the cylindrical space is depressurized for desorption, a passage is formed between the cylindrical space, the inner air intake pipe and the exhaust gas discharge pipe; When the cylindrical space is back-flushed and cleaned, the back-flushing control structure, the inner air outlet pipe, the cylindrical space, the inner air inlet pipe and the exhaust gas discharge pipe form a passage; When the annular space is back-flushed and cleaned, the back-flushing control structure, the external air intake pipe, the annular space, the external air intake pipe and the exhaust gas discharge pipe form a passage; When the cylindrical space and the annular space are pressure-equalized at the outlet end, the cylindrical space, the inner outlet main pipe, the outer outlet main pipe and the annular space form a passage; When the cylindrical space and the annular space are pressure-equalized at the air intake end, the cylindrical space, the inner air intake main pipe, the inner and outer air intake main pipes and the annular space form a passage; A sleeve-type adsorption tower structure is adopted to use the heat released during the adsorption process of the first cylindrical space or the second cylindrical space as the heat required for desorption of the first annular space or the second annular space.

2. A pressure swing adsorption oxygen production system with parallel telescopic adsorption towers operating in different phases as claimed in claim 1, characterized in that: Each inner air inlet is connected to an inner air inlet branch pipe, and the inner air inlet branches of all adsorption towers are collected and connected to the inner air inlet main pipe; each outer air inlet is connected to an outer air inlet branch pipe, and the outer air inlet branches of all adsorption towers are collected and connected to the outer air inlet main pipe; each inner air outlet is connected to an inner air outlet branch pipe, and the inner air outlet branches of all adsorption towers are collected and connected to the inner air outlet main pipe; each outer air outlet is connected to an outer air branch pipe, and the outer air branch pipes of all adsorption towers are collected and connected to the outer air main pipe; the inner air inlet main pipe and the outer air inlet main pipe are both provided with valves for controlling the on-off of this section of the pipeline; the inner air outlet main pipe and the outer air outlet main pipe are also both provided with valves for controlling the on-off of this section of the pipeline.

3. A pressure swing adsorption oxygen production system with parallel telescopic adsorption towers operating in different phases as claimed in claim 1, characterized in that: The waste gas discharge pipeline is provided with a waste gas discharge valve; the product gas discharge pipeline is provided with a gas outlet control valve, an oxygen buffer tank and a pressure regulating valve in sequence.

4. A pressure swing adsorption oxygen production system with parallel telescopic adsorption towers in heterogeneous operation as claimed in claim 1, characterized in that: The cylindrical space is filled with at least two layers of adsorption material with different particle diameters along the direction of the inner air inlet toward the inner air outlet, and the particle diameter of the adsorption material layer gradually increases along the direction of the inner air inlet toward the inner air outlet; the annular space is filled with at least two layers of adsorption material with different particle diameters along the direction of the outer air inlet toward the outer air outlet, and the particle diameter of the adsorption material layer gradually increases along the direction of the inner air inlet toward the inner air outlet.

5. A pressure swing adsorption oxygen production system with parallel telescopic adsorption towers in heterogeneous operation as claimed in claim 3, characterized in that: Adsorption material layers in the same cylindrical space or the same annular space are separated by a perforated plate with a plurality of circular through holes; the outer end of the adsorption material layer located at the inner air outlet side end in the cylindrical space is compressed, and the outer end of the adsorption material layer located at the outer air outlet side end in the annular space is compressed.

6. A method for heterogeneous operation of parallel telescopic adsorption towers, characterized in that: A pressure swing adsorption oxygen production system using a parallel sleeve-type adsorption tower out-of-phase operation as claimed in any one of claims 1 to 4 has the following cyclic operation steps: A. The inner air intake pipe, cylindrical space, inner air outlet pipe and product gas discharge pipeline form a passage, and the cylindrical space is adsorbed and separated; at the same time, the annular space, the outer air intake pipe and the waste gas discharge pipeline form a passage, and the annular space is depressurized and desorbed; B. The inner air inlet pipe, cylindrical space, inner air outlet pipe and product gas discharge pipeline form a passage, and the cylindrical space is adsorbed and separated; at the same time, the backflush control structure, the outer air outlet pipe, the annular space, the outer air inlet pipe and the waste gas discharge pipeline form a passage, and the annular space is backflush and cleaned; C. The cylindrical space, the inner air outlet pipe, the outer air outlet pipe and the annular space form a passage, and the cylindrical space and the annular space are pressure-equalized at the air outlet end; D. The cylindrical space, the inner air intake pipe, the inner and outer air intake pipes and the annular space form a passage, and the cylindrical space and the annular space are pressure-equalized at the air intake end; E. The outer air intake pipe, the annular space, the outer air intake pipe and the product gas discharge pipeline form a passage, and the annular space is adsorbed and separated; at the same time, the cylindrical space, the inner air intake pipe and the waste gas discharge pipeline form a passage, and the cylindrical space is depressurized and desorbed; F. The external air inlet pipe, the annular space, the external air outlet pipe and the product gas discharge pipeline form a passage, and the annular space is adsorbed and separated; at the same time, the backflush control structure, the internal air outlet pipe, the cylindrical space, the internal air inlet pipe and the waste gas discharge pipeline form a passage, and the cylindrical space is backflush and cleaned; G. The cylindrical space, the inner air outlet pipe, the outer air outlet pipe and the annular space form a passage, and the cylindrical space and the annular space are pressure-equalized at the air outlet end; H. The cylindrical space, the inner air intake pipe, the inner and outer air intake pipes and the annular space form a passage, and the cylindrical space and the annular space are pressure-equalized at the air intake end.

7. A method for heterogeneous operation of parallel telescopic adsorption towers as claimed in claim 5, characterized in that: The pressure equalization time at the outlet end of the cylindrical space and the annular space is 0.5~2s, and the pressure equalization time at the inlet end of the cylindrical space and the annular space is 1~5s.

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