Single-tower VPSA (Vacuum Pressure Swing Adsorption) oxygen production equipment based on reversible pump

Abstract

The utility model discloses single-tower VPSA (Vacuum Pressure Swing Adsorption) oxygen production equipment based on a reversible pump, which comprises a gas inlet filter, the reversible pump, a heat dissipation device, an adsorption tower, an oxygen buffer tank, a flushing gas buffer tank, an electromagnetic valve group, a gas pipeline, a control module and a variable frequency motor, the outlet end of the oxygen buffer tank is connected with a flowmeter. Under the control of the programmable logic control module, the operation direction of the reversible pump is adjusted through the variable frequency motor, the pressure conversion in the adsorption tower is realized, and the oxygen production process is completed by circularly executing four steps of boosting adsorption, depressurization, flushing and boosting. The reversible fan is adopted to effectively replace an air blower and a vacuum pump, so that the volume of oxygen production equipment is reduced, and the integration level of the equipment is effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of oxygen production, in particular to a single-tower VPSA oxygen production device based on a reversible pump. Background Art

[0002] In terms of medical support, oxygen support is a key content. Timely oxygen supply is one of the key measures to treat the wounded and sick, especially in the process of plateau medical support. There are many problems in the transportation of bottled oxygen, such as high consumption of transportation capacity, long transportation time, and delayed support time. Sustainable on-site preparation of oxygen can effectively solve the above problems and meet the support needs.

[0003] At present, the main method for sustainable on-site oxygen production is pressure swing adsorption. The principle of oxygen production by pressure swing adsorption (PSA) is that when air passes through a zeolite molecular sieve, due to its selective adsorption characteristics for gases, N2 is adsorbed, and O2 flows out through the adsorption tower as a product gas, thereby achieving the purpose of air separation and oxygen production. The oxygen produced by this method has a purity of more than 90%. Currently, the most common technology is multi-tower pressure swing adsorption oxygen production technology, and there is less research on single-tower pressure swing adsorption oxygen production. Due to the large number of equipment and complex processes, the multi-tower process is not as easy to implement as the single-tower pressure swing adsorption oxygen production process in terms of miniaturization, integration, and integration. The traditional pressure swing adsorption cycle process requires a high adsorption pressure, resulting in high energy consumption. Vacuum pressure swing adsorption oxygen production is adsorbed under normal pressure or high pressure, and desorbed under vacuum. The pressure required for the adsorption process is relatively low. The heat effect of air compression during air intake within its pressure range is relatively low. The pressure standards for the pipe wall of the gas path and the adsorption tower are lower, and the equipment requirements are low. Water does not condense within this pressure range, and no pre-water removal equipment is required. The energy consumption required for the process is low, and the molecular sieve is not easy to pulverize under this application condition, which is conducive to extending the life of the molecular sieve. The combination of two device modules, a blower and a vacuum pump, is commonly used in the vacuum pressure swing adsorption (VPSA) process to complete the pressure conversion. In order to improve the integration of the equipment, a reversible fan plus a motor is used in the prior art to replace the traditional "one-to-two" pressure conversion module of a blower, a vacuum pump and a motor. If the traditional "one-to-two" module is used, the complexity of the pipeline system and the control system increases, and the consumables and space occupancy increase, which cannot meet the needs of miniaturization and high integration. The utility model provides a technical solution that utilizes a reversible fan to replace a blower and a vacuum pump, thereby reducing the volume of a single-tower oxygen production device and improving the integration of the device. Utility Model Content

[0004] The problem to be solved by the utility model is to provide a miniaturized single-tower VPSA oxygen production equipment based on a reversible pump.

[0005] To achieve the above-mentioned purpose, the embodiment of the utility model discloses a single-tower VPSA oxygen production equipment based on a reversible pump, comprising: a reversible pump, a heat dissipation device, an adsorption tower, an oxygen buffer tank and a flushing gas buffer tank; and a programmable logic control module and a variable frequency motor;

[0006] The gas path of the reversible pump outlet is connected to the heat sink, and the gas path of the heat sink is connected to the air inlet of the adsorption tower; the reversible pump circuit is connected to the variable frequency motor;

[0007] The gas outlet of the adsorption tower is connected to the oxygen buffer tank and the flushing gas buffer tank; an oxygen concentration sensor and a pressure sensor are arranged on the top of the adsorption tower;

[0008] A one-way valve is provided in front of the air inlet of the oxygen buffer tank;

[0009] A flow meter is provided behind the gas outlet of the oxygen buffer tank;

[0010] A first solenoid valve is provided in front of the air inlet of the flushing gas buffer tank;

[0011] The programmable logic control module circuit is connected to the oxygen concentration sensor, the pressure sensor, the first solenoid valve and the variable frequency motor.

[0012] As an optional implementation, the reversible pump is a Roots blower, the programmable logic control module controls the variable frequency motor to realize the forward and reverse switching of the reversible pump, and the operating states of the reversible pump include: acceleration, constant speed, deceleration and direction switching; the exhaust volume of the reversible pump is greater than 3m 3 / min.

[0013] As an optional implementation, the reversible pump is a lubricating oil-free pump.

[0014] As an optional implementation, the heat dissipation device includes a serpentine-coiled copper tube and a fan arranged under the copper tube.

[0015] As an optional implementation, the adsorption tower is filled with LiX molecular sieve, the height-to-diameter ratio of the adsorption tower is in the range of 1-10, and the bottom of the adsorption tower is filled with water-absorbing adsorbent alumina.

[0016] As an optional implementation, the air inlet of the reversible pump is provided with an air filter.

[0017] As an optional implementation, the variable frequency motor is a variable frequency speed regulating motor, and the system pressure variation range is 0.3 bar to 2 bar. It should be noted that bar is a commonly used pressure unit, 1 bar = 0.1 MPa, and the pressures described in this application are all absolute pressures.

[0018] As an optional implementation, the programmable logic control module has a program writing function; adjusts the operating direction, operating time, and operating frequency of the reversible pump through human-computer interaction; sets the valve opening and closing conditions and time in the oxygen production equipment system to complete the operation adjustment and monitoring of the process; and simultaneously collects key information in the process to monitor the operation of the reversible pump, the prepared oxygen concentration, and the adsorption tower pressure information in real time.

[0019] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0020] 1. The technical solution provided by the utility model adopts a reversible fan to effectively replace the blower and vacuum pump to achieve pressure conversion, simplify the gas pipeline channel and related control system, reduce the volume of the oxygen production equipment, and effectively improve the equipment integration;

[0021] 2. The technical solution provided by the utility model is controlled by a programmable logic control module with a high degree of freedom. The operating parameters of the reversible pump can be defined by the user, and its operating time and operating frequency can be controlled. The pressure in the system is controllable and adjustable. The flushing gas source, the operating time of each step, the time parameters such as valve opening and closing can be defined by the user. For oxygen preparation under different conditions in plains and plateaus, it can be adjusted to the optimal operating state according to local conditions, thereby improving the adsorption efficiency and having a wide range of applications.

[0022] 3. The technical solution provided by the utility model can be used as an experimental platform for scientific research on vacuum pressure swing adsorption oxygen production. It has a high degree of freedom, and the connection between modules and components is easy to disassemble and assemble. Instruments can be installed at different positions; the molecular sieve in the adsorption tower can be replaced; the programmable logic control module can customize the program. The utility model is conducive to promoting the development of single reversible pump vacuum pressure swing adsorption oxygen production equipment and process methods, and is of great significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic structural diagram of a single-tower VPSA oxygen production equipment based on a reversible pump disclosed in an embodiment of the utility model;

[0024] Figure 2 A flow chart of a single-tower VPSA oxygen production method based on a reversible pump disclosed in an embodiment of the utility model;

[0025] Figure 3 The invention discloses a reversible pump operation control in a single-tower VPSA oxygen production equipment process based on a reversible pump.

[0026] Figure 4 The present invention discloses a control flow of a programmable logic control module in a single-tower VPSA oxygen production equipment based on a reversible pump.

[0027] Reference numerals and descriptions:

[0028] 1. Reversible pump, 2. Heat dissipation device, 3. Adsorption tower, 4. Oxygen buffer tank, 5. Flushing gas buffer tank, 6. Programmable logic control module, 7. Frequency conversion motor, 8. Oxygen concentration sensor, 9. Pressure sensor, 10. Check valve, 11. First solenoid valve, 12. Air filter, 13. Flow meter. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0030] Embodiment 1

[0031] See also Figure 1 . Figure 1 The utility model discloses a single-tower VPSA oxygen production equipment based on a reversible pump.

[0032] like Figure 1 As shown, a single-tower VPSA oxygen production device based on a reversible pump disclosed in an embodiment of the utility model includes: a reversible pump 1, a heat dissipation device 2, an adsorption tower 3, an oxygen buffer tank 4 and a flushing gas buffer tank 5; and a programmable logic control module 6 and a variable frequency motor 7;

[0033] The gas path of the gas outlet of the reversible pump 1 is connected to the heat sink 2, and the gas path of the heat sink 2 is connected to the gas inlet of the adsorption tower 3; the circuit of the reversible pump 1 is connected to the variable frequency motor 7;

[0034] The gas outlet of the adsorption tower 3 is connected to the oxygen buffer tank 4 and the flushing gas buffer tank 5; an oxygen concentration sensor 8 and a pressure sensor 9 are arranged on the top of the adsorption tower 3;

[0035] A one-way valve 10 is provided in front of the air inlet of the oxygen buffer tank 4;

[0036] A flow meter 13 is provided behind the gas outlet of the oxygen buffer tank 4;

[0037] A first solenoid valve 11 is provided in front of the air inlet of the flushing gas buffer tank 5;

[0038] The programmable logic control module 6 is circuit-connected to the oxygen concentration sensor 8 , the pressure sensor 9 , the first solenoid valve 11 and the variable frequency motor 7 .

[0039] In another optional embodiment, the reversible pump 1 is a Roots blower, and the programmable logic control module 6 controls the variable frequency motor 7 to realize the forward and reverse switching of the reversible pump 1. The operating states of the reversible pump 1 include: acceleration, constant speed, deceleration and direction switching; the exhaust volume of the reversible pump 1 is greater than 3m 3 / min. Thus, the pressure of the oxygen production process system is changed. When the rotation is forward, the ambient air is blown into the adsorption tower 3, and the pressure in the adsorption tower 3 increases due to gas compression; when the direction is switched, the pressure in the oxygen production system adsorption tower 3 and the gas path is equalized with the external environment; when the rotation is reversed, the pressure in the adsorption tower 3 and the gas path is discharged to reduce the pressure.

[0040] In yet another optional embodiment, the reversible pump 1 is a lubricating oil-free pump.

[0041] In another optional embodiment, the heat dissipation device 2 includes a copper tube coiled in a serpentine shape and a fan arranged under the copper tube. The copper tube coiled in a serpentine shape can increase the heat dissipation area; the fan is arranged on the copper tube to further enhance the heat dissipation efficiency.

[0042] It should be noted that the temperature of the air will rise after being compressed, which not only affects the safety of the reversible pump 1, but also because the adsorption process is an exothermic process, the adsorption capacity of the adsorbent for nitrogen decreases as the temperature rises, and the adsorption effect decreases. Therefore, the heat dissipation device 2 is used to cool the air to achieve a better adsorption effect, improve the use efficiency of the adsorbent, and increase the oxygen production. At the same time, it increases environmental adaptability and can achieve a better adsorption effect in a high temperature environment.

[0043] In another optional embodiment, the adsorption tower 3 is filled with LiX molecular sieve, which has higher nitrogen and oxygen selectivity than the commonly used 5A and NaX molecular sieves in industry, and has a high adsorption capacity for nitrogen in the low pressure range, which is conducive to the adsorption of nitrogen and the increase of production. At the same time, due to the use of low-pressure special LiX molecular sieve, the required pressure in the adsorption tower 3 is smaller to meet the oxygen production demand, which is more energy-saving than other molecular sieves and more conducive to medical security use in different environments. In order to ensure the efficient use of molecular sieves, aluminum oxide is filled at the bottom of the adsorption tower to absorb moisture. The height-to-diameter ratio of the adsorption tower 3 is in the range of 1-10, and the height-to-diameter ratio of the adsorption tower 3 is preferably 1. The lower aspect ratio is conducive to assembly in a box-type device. In order to improve the uniform flow distribution of the intake air in the radial direction and avoid the excessively fast gas passing speed of the low utilization rate of the external molecular sieve, an air flow distributor is provided at the bottom of the adsorption tower 3. After air flow simulation, it is shown that the purpose of uniform flow of the intake air in the radial direction can be achieved.

[0044] In another optional embodiment, the adsorption tower 3 may be filled with adsorption materials such as 13X molecular sieve, activated carbon, metal organic framework material, porous polymer, etc. to perform carbon separation, organic gas separation, etc. The device can be used for pressure swing adsorption separation of different gases.

[0045] In another optional embodiment, the air inlet of the reversible pump 1 is provided with an air filter 12. The air intake volume of the reversible pump 1 is 3m 3 / min or more, when a large flow of gas flows in, the pre-air filter 12 can effectively perform preliminary filtration to block impurities such as dust and moisture in the air to prevent it from entering the pump and piping system and affecting its normal operation.

[0046] In another optional embodiment, the reversible pump 1 is connected to a motor, which is a variable frequency speed regulating motor controlled by a programmable logic control module 6 to drive the reversible pump 1 to operate and reverse, thereby meeting the requirements of this process.

[0047] In another optional embodiment, the programmable logic control module 6 adjusts the acceleration, constant speed, deceleration time and direction switching duration of the reversible pump, changes the given operating frequency of the pump, sets the negative pressure and positive pressure working time, and adjusts the opening and closing time and duration of each valve; adds or deletes module components such as gas flow meters, valves, etc. by writing programs, and configures the operation interface information.

[0048] Embodiment 2

[0049] See also Figure 2 . Figure 2 This is a flow chart of a single-tower VPSA oxygen production method based on a reversible pump disclosed in an embodiment of the utility model. This embodiment is based on the single-tower VPSA oxygen production equipment based on a reversible pump disclosed in Example 1. Figure 2 As shown, the utility model embodiment discloses a single-tower VPSA oxygen production method based on a reversible pump, comprising:

[0050] S1, negative pressure preparation process; specifically: the one-way valve 10 and the solenoid valve are closed; the reversible pump 1 runs in reverse, the acceleration time is t1, then runs at a constant speed for a time of t2, and finally decelerates to stop for a time of t3, reducing the pressure in the adsorption tower 3 to a negative pressure state, activating the molecular sieve, the duration of the molecular sieve activation is preferably 5 to 60 seconds, that is, the total duration of t1+t2+t3 is preferably 5 to 60 seconds; the radiator continues to operate. It should be noted that the reverse operation means that the gas in the adsorption tower is discharged through the reversible pump.

[0051] S2, boost adsorption process; specifically: the reversible pump 1 performs "reverse-forward operation direction switching" for a duration of t4, preferably 2-10 seconds, accelerates for a duration of t5, and then runs at a constant speed for a duration of t6, and the air passes through the reversible pump 1 and the heat dissipation device 2 and enters the adsorption tower 3; the pressure sensor 9 detects that the pressure rises to not less than 1.4 bar, and the oxygen concentration sensor 8 detects that the oxygen concentration at the top of the adsorption tower 3 rises to more than 90%, and the one-way valve 10 opens under the action of pressure, and oxygen flows into the oxygen buffer tank 4; the first solenoid valve 11 opens, and the opening duration t7 is preferably 2 to 10 seconds, which is mainly used to flow oxygen-enriched air into the flushing gas buffer tank 5 for flushing; the reversible pump stops running, and the deceleration duration is t8. The total duration of duration t5+t6+t8 is preferably 5-60 seconds.

[0052] Preferably, the reversible pump 1 operates in the forward direction. From the output of the reversible pump 1, the operating frequency, the scale of the adsorption tower 3 and the experimental results, it can be seen that the reversible pump 1 can reach the pressure requirement by operating at a frequency of 45Hz for 10s. In addition, the device can autonomously adjust the pump operating frequency and the acceleration, deceleration and uniform speed operation time according to different usage requirements.

[0053] Preferably, the first solenoid valve 11 is opened when the forward operation of the reversible pump 1 is about to stop, so that oxygen can flow into the oxygen buffer tank 4 .

[0054] S3, depressurization process; specifically: the reversible pump 1 performs "forward-reverse operation direction switching", the duration is t9, preferably 2-10 seconds; the pressure sensor monitors that the pressure in the adsorption tower drops to normal pressure, and the reversible pump performs a reverse operation to further reduce the pressure in the adsorption tower 3 to negative pressure; the pressure sensor 9 monitors that the pressure in the adsorption tower 3 drops to a negative pressure not higher than the desorption pressure, and the reversible pump 1 stops running.

[0055] Preferably, the desorption pressure is not higher than 0.6 bar. According to the output of the reversible pump 1, the operating frequency, the scale of the adsorption tower 3 and the experimental results, the reversible pump 1 can reach the pressure requirement by operating at a frequency of 45 Hz for 10 seconds. In addition, the device can autonomously adjust the pump operating frequency and the duration of acceleration, constant speed and deceleration according to different usage requirements.

[0056] S4, flushing process; specifically: the first solenoid valve 11 is opened for a duration of t10, so that the flushing gas flushes the adsorption tower 3 in reverse (from the top to the bottom of the adsorption tower); the first solenoid valve 11 is closed.

[0057] Preferably, the duration t10 of the flushing process is 2 to 10 seconds.

[0058] Steps S2 to S4 are executed cyclically to realize a continuous oxygen production process.

[0059] It should be noted that the above steps are completed under the control of the programmable logic control module 6. The reversible pump 1 is operated and controlled during the oxygen production process. Figure 3 As shown. The programmable logic control module 6 controls the device process as follows Figure 4 shown.

[0060] It should be noted that the above t1-t10 can be adjusted in the programmable logic control module 6, and the time adjustment range is not limited to the above recommended range.

[0061] It should be noted that this equipment can continuously produce 93±3% medical oxygen, and the oxygen flow rate fluctuation range is 30-100L / min. Under the conditions of an external environment of 25°C, an altitude of 0m, an adsorption tower with an inner diameter of 50cm and a height of 50cm, and filled with LiX molecular sieve, the oxygen output is 3m 3 / h~5m 3 / h.

[0062] It should be noted that Example 2 is a set of oxygen production process data obtained by numerically modeling and simulating the prototype using Aspen Adsorption, and repeating the experiment on the prototype for many times. The above-mentioned Aspen Adsorption is a simulation software developed by Aspen Tech for adsorption separation process.

[0063] Finally, it should be noted that the single-tower VPSA oxygen production equipment based on a reversible pump disclosed in the embodiment of the utility model is only a preferred embodiment of the utility model, which is only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that it is still possible to modify the technical solutions recorded in the aforementioned embodiments, or to replace some of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the utility model.

Claims

1. A single-tower VPSA oxygen generator based on a reversible pump, characterized in that: It comprises a reversible pump (1), a heat dissipation device (2), an adsorption tower (3), an oxygen buffer tank (4) and a flushing gas buffer tank (5); and a programmable logic control module (6) and a variable frequency motor (7); The gas path of the gas outlet of the reversible pump (1) is connected to the heat sink (2), and the gas path of the heat sink (2) is connected to the gas inlet of the adsorption tower (3); the circuit of the reversible pump (1) is connected to the variable frequency motor (7); The gas outlet of the adsorption tower (3) is connected to the oxygen buffer tank (4) and the flushing gas buffer tank (5); an oxygen concentration sensor (8) and a pressure sensor (9) are arranged on the top of the adsorption tower (3); A one-way valve (10) is provided in front of the air inlet of the oxygen buffer tank (4); A flow meter (13) is provided behind the gas outlet of the oxygen buffer tank (4); A first solenoid valve (11) is provided in front of the air inlet of the flushing gas buffer tank (5); The programmable logic control module (6) is circuit-connected to the oxygen concentration sensor (8), the pressure sensor (9), the first solenoid valve (11) and the variable frequency motor (7).

2. The single-tower VPSA oxygen production equipment based on a reversible pump according to claim 1, characterized in that: The reversible pump (1) is a Roots blower. The programmable logic control module (6) controls the variable frequency motor (7) to realize the forward and reverse switching of the reversible pump (1). The operating states of the reversible pump (1) include: acceleration, constant speed, deceleration and direction switching. The exhaust volume of the reversible pump (1) is greater than 3m 3 / min.

3. The single-tower VPSA oxygen production equipment based on a reversible pump according to claim 1, characterized in that: The reversible pump (1) is a lubricating oil-free pump.

4. The single-tower VPSA oxygen production equipment based on a reversible pump according to claim 1, characterized in that: The heat dissipation device (2) comprises a copper tube coiled in a serpentine shape and a fan arranged below the copper tube.

5. The single-tower VPSA oxygen production equipment based on a reversible pump according to claim 1, characterized in that: The adsorption tower (3) is filled with LiX molecular sieve, and the bottom of the adsorption tower (3) is filled with water-absorbing adsorbent alumina.

6. The single-tower VPSA oxygen production equipment based on a reversible pump according to claim 1, characterized in that: An air filter (12) is provided at the air inlet of the reversible pump (1).

7. The single-tower VPSA oxygen production equipment based on a reversible pump according to claim 1, characterized in that: The variable frequency motor (7) is a variable frequency speed regulating motor, which can achieve a system pressure change range of 0.3 bar to 2 bar.

8. The single-tower VPSA oxygen production equipment based on a reversible pump according to claim 1, characterized in that: The programmable logic control module (6) has a program writing function; adjusts the operation direction, operation time and operation frequency of the reversible pump through human-computer interaction; sets the valve opening and closing conditions and time in the oxygen production equipment system to complete the operation adjustment and monitoring of the process; and collects key information in the process to monitor the operation of the reversible pump, the concentration of prepared oxygen and the pressure information of the adsorption tower in real time.

Images