Air separation oxygen generating device with pressure swing adsorption and temperature swing desorption

Abstract

This invention relates to an air separation oxygen generator using pressure swing adsorption (PSA) and temperature swing desorption (TSD). Along the air transport direction, the air separation oxygen generator includes an air compressor, a refrigerated dryer, and an air buffer tank connected in sequence. The air separation oxygen generator also includes a first adsorption device, a second adsorption device, a heat exchange device, and an oxygen buffer tank. The inlets of the first and second adsorption devices are respectively connected to the air buffer tank; the outlets of the first and second adsorption devices are respectively connected to the oxygen buffer tank. The first and second adsorption devices alternately perform adsorption and desorption. The heat exchange device is connected to the air compressor and includes a cold-side inlet and a hot-side outlet. The cold-side inlet is connected to the air buffer tank, and the hot-side outlet is connected to the outlets of the first and second adsorption devices, respectively. This invention utilizes the heat generated by the air compressor for temperature swing desorption, eliminating the need for a heating device and reducing energy consumption.

Description

Technical Field

[0001] This invention relates to the field of air separation oxygen generation technology, and in particular to an air separation oxygen generation device based on pressure swing adsorption and temperature swing desorption. Background Technology

[0002] Pressure Swing Adsorption (PSA) is an important and widely used gas separation method, such as pressure swing adsorption drying, pressure swing adsorption oxygen production, nitrogen production, etc. Among them, adsorption drying is usually used to remove the moisture contained in compressed air to obtain dry compressed air with a low dew point. Traditional PSA (Pressure Swing Adsorption) methods for producing oxygen from normal atmospheric air typically employ nitrogen adsorbents such as CaA, CaX, NaX, and LiX, based on equilibrium adsorption theory. The adsorbent preferentially adsorbs nitrogen molecules, which are more polar and have a larger quadrupole moment, while oxygen and argon are relatively less readily adsorbed, thus becoming enriched in the gas phase and output as the product gas. When the adsorbent approaches adsorption saturation, the system depressurizes and regenerates the adsorbed nitrogen by reducing the pressure (or even creating a vacuum, i.e., Vacuum Pressure Swing Adsorption, VPSA), completing an adsorption-desorption cycle. Dual-tower or multi-tower systems are usually employed, with valve switching enabling continuous oxygen production.

[0003] CN119857340A discloses a pressure swing adsorption (PSA) air separation oxygen generation system and its operating method, including an air compressor, a first adsorption tower, and a second adsorption tower; the inlets of the first and second adsorption towers are respectively connected to a first inlet pipe and a second inlet pipe, and the outlet of the air compressor is connected in parallel to the inlets of the first and second inlet pipes; the outlets of the first and second adsorption towers are respectively connected to a first outlet pipe and a second outlet pipe, and the outlets of the first and second outlet pipes converge and are connected to the inlet of an output pipe, which outputs oxygen; a tail control valve is provided on the output pipe; a first inlet valve is provided on the first inlet pipe, and a second inlet valve is provided on the second inlet pipe; the inlets of the first and second adsorption towers are also respectively connected to a first desorption valve and a second desorption valve communicating with the outside; a first connecting pipe extends from the middle of the first outlet pipe, and the outer end of the first connecting pipe is connected to the first outlet valve. One end is connected; a second connecting pipe is led out from the middle of the second outlet pipe, and the outer end of the second connecting pipe is connected to one end of the second outlet valve; the other ends of the first outlet valve and the second outlet valve are connected through a third connecting pipe; a fourth connecting pipe is led out from the third connecting pipe, and the other end of the fourth connecting pipe is connected to the inlet of the first inlet pipe and the inlet of the second inlet pipe in parallel; a first angle seat valve is provided on the fourth connecting pipe; a return pipe is also led out from the middle of the output pipe, and the other end of the return pipe is connected to the third connecting pipe; a backflush control valve is provided on the return pipe; the first adsorption tower and the second adsorption tower alternately adsorb and desorb; when the first adsorption tower adsorbs and the second adsorption tower desorbs, if the oxygen concentration in the output pipe is not up to standard, this unqualified oxygen enters the second adsorption tower through the return pipe; after the second adsorption tower has completed desorption, the outlet of the first adsorption tower and the outlet of the second adsorption tower are connected in sequence, and the outlet of the first adsorption tower and the inlet of the second adsorption tower are connected in sequence. However, when using this pressure swing adsorption oxygen generator, nitrogen desorption is difficult, requiring a large amount of product gas (high-purity oxygen-enriched air), and the oxygen recovery rate is low, generally around 40% to 50% depending on the process.

[0004] The present invention aims to overcome the disadvantages of the existing pressure swing adsorption oxygen generation technology, such as low recovery rate and high energy consumption, and to provide an oxygen generation device with a relatively simple process flow, higher energy efficiency, and the ability to stably and efficiently produce oxygen-enriched air with a purity of over 90% directly from normal atmosphere. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides an air separation oxygen generation device based on pressure swing adsorption and temperature swing desorption. The present invention directly utilizes the heat generated by the air compressor for temperature swing desorption, eliminating the need for a heating device and reducing energy consumption. At the same time, by setting up two adsorption devices to alternately perform adsorption and desorption, continuous oxygen generation can be achieved.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides an air separation oxygen generation device with pressure swing adsorption and temperature swing desorption, wherein, along the air conveying direction, the air separation oxygen generation device includes an air compressor, a refrigerated dryer and an air buffer tank connected in sequence. The air separation oxygen generator also includes a first adsorption device, a second adsorption device, a heat exchange device, and an oxygen buffer tank. The inlet of the first adsorption device and the inlet of the second adsorption device are respectively connected to an air buffer tank; The outlets of the first adsorption device and the second adsorption device are respectively connected to an oxygen buffer tank; The first adsorption device and the second adsorption device alternately perform adsorption and desorption; The heat exchange device is connected to an air compressor, and the heat exchange device also includes a cold-side inlet and a hot-side outlet; the cold-side inlet is connected to an air buffer tank, and the hot-side outlet is connected to the outlet of the first adsorption device and the outlet of the second adsorption device, respectively.

[0007] This invention first compresses air, which is then dried in a refrigerated dryer to remove water and oil before entering an air buffer tank. The compressed air then enters a first adsorption device for adsorption treatment. After adsorption, oxygen flows out of the first adsorption device and into an oxygen buffer tank. Simultaneously, a small portion of the compressed air in the air buffer tank enters a heat exchange device, where the heat generated by the air compressor is used to raise the temperature of the compressed air. The heated compressed air then enters a second adsorption device to heat the molecular sieve bed for desorption treatment. By setting up two adsorption devices that alternately perform adsorption and desorption, this invention can achieve continuous oxygen production. Furthermore, it directly utilizes the heat generated by the air compressor for temperature-variable desorption, eliminating the need for a separate heating device and reducing energy consumption.

[0008] It should be noted that, in this invention, the inlet of the first adsorption device and the inlet of the second adsorption device refer to the compressed air inlet at the top of the first adsorption device and the second adsorption device during the adsorption stage; similarly, the outlet of the first adsorption device and the outlet of the second adsorption device refer to the oxygen outlet at the bottom of the first adsorption device and the second adsorption device during the adsorption stage.

[0009] As a preferred embodiment of the present invention, the inlet of the first adsorption device is connected to the outlet of the second adsorption device.

[0010] Preferably, the inlet of the second adsorption device is connected to the outlet of the first adsorption device.

[0011] As a preferred technical solution of the present invention, the inlet and outlet of the first adsorption device are respectively provided with pneumatic programmable valves, and the pneumatic programmable valves are connected to a programmable logic controller (PLC controller).

[0012] The PLC controller in this invention can achieve automatic switching.

[0013] Preferably, the inlet and outlet of the second adsorption device are respectively provided with pneumatic programmable valves, and the pneumatic programmable valves are connected to a PLC controller.

[0014] Preferably, the heat exchange device includes a plate-fin heat exchanger.

[0015] As a preferred embodiment of the present invention, the inlet of the first adsorption device and the inlet of the second adsorption device are respectively connected to a first air inlet pipe and a second air inlet pipe.

[0016] Preferably, the outlet of the air buffer tank is connected in parallel to the inlet of the first air intake pipe and the inlet of the second air intake pipe.

[0017] As a preferred embodiment of the present invention, the inlet of the first adsorption device and the inlet of the second adsorption device are respectively connected to a first desorption valve and a second desorption valve that communicate with the outside world.

[0018] Preferably, the first and second parsing valves are connected to the outside world in parallel.

[0019] As a preferred embodiment of the present invention, the outlets of the first adsorption device and the second adsorption device are respectively connected to a first gas outlet pipe and a second gas outlet pipe.

[0020] Preferably, along the oxygen output direction, the first outlet pipe is connected to a first connecting pipe, a third connecting pipe, and a fifth connecting pipe, respectively.

[0021] Preferably, along the oxygen output direction, the second outlet pipe is connected to the second connecting pipe, the fourth connecting pipe, and the sixth connecting pipe, respectively.

[0022] As a preferred embodiment of the present invention, the air separation oxygen generator further includes an oxygen collection pipe and a return pipe connected to an oxygen buffer tank.

[0023] Preferably, the oxygen buffer tank is connected to the oxygen collection pipe and the return pipe in parallel.

[0024] Preferably, the oxygen collection tube is equipped with an oxygen concentration detector and a one-way valve.

[0025] This invention incorporates an oxygen concentration detector and a one-way valve on the oxygen collection pipe. The one-way valve effectively prevents oxygen from flowing back into the adsorption device through the oxygen collection pipe. Instead, the oxygen enters the adsorption device undergoing the desorption process through the return pipe. Since the oxygen concentration is much higher than that of air, the oxygen entering the adsorption device will carry away the adsorbed nitrogen, effectively regenerating the adsorption capacity of the molecular sieve.

[0026] As a preferred embodiment of the present invention, the first connecting pipe and the second connecting pipe are connected to the oxygen collection pipe in parallel.

[0027] Preferably, the third connecting pipe and the fourth connecting pipe are connected to the return pipe in parallel.

[0028] As a preferred embodiment of the present invention, the hot-side outlet is connected to the first adsorption device via a fifth connecting pipe.

[0029] Preferably, the hot-side outlet is connected to the second adsorption device via a sixth connecting pipe.

[0030] Preferably, the fifth connecting pipe and the sixth connecting pipe are connected to the hot-side outlet in parallel.

[0031] As a preferred embodiment of the present invention, the interior of the first adsorption device and the interior of the second adsorption device are each independently filled with Li-LSX type molecular sieves.

[0032] In this invention, the adsorption device is filled with Li-LSX type molecular sieves because Li in the Li-LSX type molecular sieves... + The strong electric field can enhance its interaction with nitrogen molecules, allowing it to adsorb more nitrogen and achieve better separation, thereby further increasing the oxygen recovery rate.

[0033] The working principle of this invention is as follows: In the initial state, the first adsorption device is in the adsorption stage and the second adsorption device is in the regeneration stage. The air is pressurized to 0.5~0.6MPa by the air compressor, and after being dehydrated and degreased by the refrigerated dryer, it enters the air buffer tank. Then, it enters the first adsorption device from the top inlet of the first adsorption device. The nitrogen in the air is adsorbed by the molecular sieve, and the oxygen flows out from the bottom and enters the oxygen buffer tank. Meanwhile, the second adsorption unit undergoes heating, desorption, and regeneration. Air from the air buffer tank is sent to the cold side of the heat exchange unit to absorb the oil temperature from the air compressor, raising the temperature from room temperature to about 60-80°C. Then, hot air enters the second adsorption unit from the bottom to heat and clean the molecular sieve bed, causing the adsorbed nitrogen to desorb. The desorbed high-temperature nitrogen-containing mixed gas is discharged from the top of the second adsorption unit. After regeneration, room temperature compressed air continues to be introduced to cool the second adsorption device until the temperature inside the adsorption device drops below 40°C, and then the adsorption stage begins. The two adsorption devices alternate in a cycle to achieve continuous oxygen production.

[0034] Compared with the prior art, the present invention has at least the following beneficial effects: This invention achieves continuous oxygen production by setting up two adsorption devices that alternately perform adsorption and desorption. At the same time, this invention directly utilizes the heat generated by the air compressor for temperature-variable desorption, eliminating the need for a heating device and reducing energy consumption. The purity of the oxygen-enriched air produced by this invention can reach over 94%. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the air separation oxygen generation device with pressure swing adsorption and temperature swing desorption provided in Embodiment 1 of the present invention.

[0036] Among them, 1-air compressor; 2-refrigerated dryer; 3-air buffer tank; 4-first adsorption device; 5-second adsorption device; 6-oxygen buffer tank; 7-heat exchange device. Detailed Implementation

[0037] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0038] Example 1 This embodiment provides an air separation oxygen generation device based on pressure swing adsorption and temperature swing desorption, such as... Figure 1 As shown, along the air transport direction, the air separation oxygen generator includes an air compressor 1, a refrigerated dryer 2, and an air buffer tank 3 connected in sequence; the air separation oxygen generator also includes a first adsorption device 4, a second adsorption device 5, a heat exchange device 7, and an oxygen buffer tank 6, wherein the inlet of the first adsorption device 4 is connected to the outlet of the second adsorption device 5; the inlet of the second adsorption device 5 is connected to the outlet of the first adsorption device 4; the first adsorption device 4 and the second adsorption device 5 alternately perform adsorption and desorption; the interior of the first adsorption device 4 and the interior of the second adsorption device 5 are each independently filled with Li-LSX type molecular sieves, and the heat exchange device 7 is a plate-fin heat exchanger.

[0039] The inlet of the first adsorption device 4 and the inlet of the second adsorption device 5 are respectively connected to a first air inlet pipe and a second air inlet pipe; the outlet of the air buffer tank 3 is connected to the inlet of the first air inlet pipe and the inlet of the second air inlet pipe in parallel; the inlet of the first adsorption device 4 and the inlet of the second adsorption device 5 are also respectively connected to a first desorption valve and a second desorption valve that are connected to the outside in parallel.

[0040] The outlets of the first adsorption device 4 and the second adsorption device 5 are respectively connected to a first outlet pipe and a second outlet pipe; along the oxygen output direction, the first outlet pipe is respectively connected to a first connecting pipe, a third connecting pipe and a fifth connecting pipe, and the second outlet pipe is respectively connected to a second connecting pipe, a fourth connecting pipe and a sixth connecting pipe. The inlet and outlet of the first adsorption device 4 are respectively equipped with pneumatic programmable valves, and the inlet and outlet of the second adsorption device 5 are respectively equipped with pneumatic programmable valves. The pneumatic programmable valves are connected to a PLC controller.

[0041] The air separation oxygen generator also includes an oxygen collection pipe and a return pipe connected in parallel with the oxygen buffer tank 6; the oxygen collection pipe is equipped with an oxygen concentration detector and a one-way valve, the first connecting pipe and the second connecting pipe are connected to the oxygen collection pipe in parallel; the third connecting pipe and the fourth connecting pipe are connected to the return pipe in parallel.

[0042] The heat exchange device 7 is connected to the air compressor 1. The heat exchange device 7 also includes a cold side inlet and a hot side outlet. The cold side inlet is connected to the air buffer tank 3. The fifth connecting pipe and the sixth connecting pipe are connected to the hot side outlet in parallel.

[0043] Example 2 This embodiment provides an air separation oxygen generation device based on pressure swing adsorption and temperature swing desorption. The only difference from Embodiment 1 is that the molecular sieves inside the first adsorption device and the second adsorption device are replaced with CaX molecular sieves instead of Li-LSX molecular sieves. All other aspects are the same as in Embodiment 1.

[0044] Comparative Example 1 This comparative example provides an adsorption-air separation oxygen generation device based on pressure swing adsorption and temperature swing desorption. The only difference between this example and Example 1 is that the heat exchange device is replaced with an air heater. All other aspects are the same as in Example 1.

[0045] Comparative Example 2 This comparative example provides an adsorption air separation oxygen generation device, which differs from Example 1 only in that the pressure swing adsorption temperature swing desorption air separation oxygen generation device does not include a heat exchange device, that is, it generates oxygen by pressure swing adsorption and pressure swing desorption air separation. Otherwise, it is the same as Example 1.

[0046] The oxygen purity in the oxygen buffer tanks of the above embodiments and comparative examples was detected using an oxygen analyzer, and the formula was used: The oxygen recovery rate was calculated, and the results are shown in Table 1.

[0047] Table 1 The test results show that: (1) As can be seen from Example 1, the present invention can achieve continuous oxygen production by setting two adsorption devices to perform adsorption and desorption alternately. At the same time, the present invention directly uses the heat generated by the air compressor for temperature-variable desorption, without the need to set up a heating device, so as to reduce energy consumption. The purity of the oxygen-enriched air produced by the present invention can reach 96%.

[0048] (2) As can be seen from Examples 1 and 2, the present invention is filled with Li-LSX molecular sieves in both the first adsorption device and the second adsorption device. Li-LSX molecular sieves can preferentially adsorb nitrogen molecules with stronger polarity and larger quadrupole moment, while oxygen and argon are relatively difficult to be adsorbed, thus being enriched in the gas phase and output as product gas to further improve oxygen purity and oxygen recovery rate.

[0049] (3) As can be seen from Example 1 and Comparative Example 1, although the setting of heat exchange device and setting of air heater have no effect on the oxygen recovery effect, the use of heat generated by air compressor for temperature-variable desorption can reduce energy consumption.

[0050] (4) As can be seen from Example 1 and Comparative Example 2, compared with pressure swing adsorption and pressure swing desorption air separation oxygen production, pressure swing adsorption and temperature swing desorption air separation oxygen production not only has low energy consumption, but also improves the purity of oxygen and the oxygen recovery rate.

[0051] In summary, this invention achieves continuous oxygen production by setting up two adsorption devices that alternately perform adsorption and desorption. At the same time, this invention directly utilizes the heat generated by the air compressor for temperature-variable desorption, eliminating the need for a heating device and reducing energy consumption. The purity of the oxygen-enriched air produced by this invention can reach over 94%.

[0052] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. An air separation oxygen generating plant with pressure swing temperature swing desorption, characterized in that, Along the air transport direction, the air separation oxygen generator includes an air compressor, a refrigerated dryer, and an air buffer tank connected in sequence; The air separation oxygen generator also includes a first adsorption device, a second adsorption device, a heat exchange device, and an oxygen buffer tank. The inlet of the first adsorption device and the inlet of the second adsorption device are respectively connected to an air buffer tank; The outlets of the first adsorption device and the second adsorption device are respectively connected to an oxygen buffer tank; The first adsorption device and the second adsorption device alternately perform adsorption and desorption; The heat exchange device is connected to an air compressor, and the heat exchange device also includes a cold-side inlet and a hot-side outlet; the cold-side inlet is connected to an air buffer tank, and the hot-side outlet is connected to the outlet of the first adsorption device and the outlet of the second adsorption device, respectively.

2. The air separation oxygen plant of claim 1 wherein, The inlet of the first adsorption device is connected to the outlet of the second adsorption device; Preferably, the inlet of the second adsorption device is connected to the outlet of the first adsorption device.

3. The air separation oxygen plant of claim 1 or 2, wherein, The inlet and outlet of the first adsorption device are respectively equipped with pneumatic programmable valves, and the pneumatic programmable valves are connected to a PLC controller; Preferably, the inlet and outlet of the second adsorption device are respectively provided with pneumatic programmable valves, and the pneumatic programmable valves are connected to a PLC controller; Preferably, the heat exchange device includes a plate-fin heat exchanger.

4. Air separation oxygen plant according to any of claims 1 to 3, characterized in that The inlet of the first adsorption device and the inlet of the second adsorption device are respectively connected to a first air inlet pipe and a second air inlet pipe; Preferably, the outlet of the air buffer tank is connected in parallel to the inlet of the first air intake pipe and the inlet of the second air intake pipe.

5. The air separation oxygen producing plant according to any one of claims 1 to 4, characterized in that, The inlets of the first adsorption device and the second adsorption device are respectively connected to a first desorption valve and a second desorption valve that communicate with the outside world; Preferably, the first and second parsing valves are connected to the outside world in parallel.

6. The air separation oxygen generator according to any one of claims 1-5, characterized in that, The outlets of the first adsorption device and the second adsorption device are respectively connected to a first gas outlet pipe and a second gas outlet pipe. Preferably, along the oxygen output direction, the first outlet pipe is connected to a first connecting pipe, a third connecting pipe, and a fifth connecting pipe, respectively; Preferably, along the oxygen output direction, the second outlet pipe is connected to the second connecting pipe, the fourth connecting pipe, and the sixth connecting pipe, respectively.

7. The air separation oxygen generator according to claim 6, characterized in that, The air separation oxygen generator also includes an oxygen collection pipe and a return pipe connected to an oxygen buffer tank. Preferably, the oxygen buffer tank is connected to the oxygen collection pipe and the return pipe in parallel; Preferably, the oxygen collection tube is equipped with an oxygen concentration detector and a one-way valve.

8. The air separation oxygen generator according to claim 7, characterized in that, The first connecting pipe and the second connecting pipe are connected to the oxygen collection pipe in parallel; Preferably, the third connecting pipe and the fourth connecting pipe are connected to the return pipe in parallel.

9. The air separation oxygen generator according to any one of claims 6-8, characterized in that, The hot-side outlet is connected to the first adsorption device via a fifth connecting pipe; Preferably, the hot-side outlet is connected to the second adsorption device via a sixth connecting pipe; Preferably, the fifth connecting pipe and the sixth connecting pipe are connected to the hot-side outlet in parallel.

10. The air separation oxygen generator according to any one of claims 1-9, characterized in that, The interior of the first adsorption device and the interior of the second adsorption device are each independently filled with Li-LSX type molecular sieves.

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