Pressure swing adsorption oxygen purification device and pressure swing adsorption oxygen generator

Abstract

The invention discloses a pressure swing adsorption oxygen purification device which comprises a plurality of adsorption towers, each adsorption tower is connected with a mixed gas inlet pipeline, a gas exhaust pipeline, a high-purity oxygen outlet pipeline and a high-purity oxygen purging pipeline; wherein each adsorption tower is subjected to a first purging step and a second purging step in sequence after exhausting; in the first purging step, mixed gas enters an adsorption tower through a mixed gas inlet pipeline; in the second purging step, high-purity oxygen enters the adsorption tower from a high-purity oxygen purging pipeline; the total gas inlet amount of the first purging step is smaller than the total gas inlet amount of the second purging step, and the gas consumption amount of the first purging step and the gas consumption amount of the second purging step are enough, so that when the pressure swing adsorption gas production is stable, mixed gas in a certain space close to and far away from the high-purity oxygen inlet end of each adsorption tower is extracted; the oxygen concentration is not less than a first preset value. According to the invention, the oxygen concentration in the desorption gas can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure swing adsorption, and more specifically, to a pressure swing adsorption oxygen purification device and a pressure swing adsorption oxygen generator. Background Art

[0002] After years of development, pressure swing adsorption technology has become a gas separation technology widely used in industrial or civilian fields such as oxygen production, nitrogen production, and hydrogen production. The basic principle of pressure swing adsorption technology is to use molecular sieves to have a good adsorption effect on part of the gas in the mixed gas and a poor adsorption effect on the other part of the gas, thereby achieving the separation of the two parts of the gas. Compared with cryogenic methods or other chemical methods, pressure swing adsorption technology has many advantages such as simple structure, good reliability, low cost, and high efficiency.

[0003] In order to improve the oxygen purity of PSA oxygen generator in the prior art, the solution adopted is to first adsorb the oxygen in the mixed gas through an adsorbent, and then desorb the oxygen in the adsorption tower as the product gas. However, the oxygen concentration of the PSA oxygen generator designed with the above solution is limited by the impurity gas in the adsorption tower and can only reach 99.1% to 99.2%, which cannot meet the 99.5% standard of medical oxygen. Summary of the invention

[0004] In view of at least one defect or improvement need in the prior art, the present invention provides a pressure swing adsorption oxygen purification device and a pressure swing adsorption oxygen generator, which can effectively improve the oxygen concentration of pressure swing adsorption oxygen production.

[0005] To achieve the above object, according to a first aspect of the present invention, a pressure swing adsorption oxygen purification device is provided, characterized in that:

[0006] It includes several adsorption towers;

[0007] Each of the adsorption towers comprises a mixed gas inlet pipeline and an exhaust pipeline;

[0008] Each of the adsorption towers also includes a high-purity oxygen outlet pipeline and a high-purity oxygen purge pipeline;

[0009] Wherein, after exhausting, each adsorption tower performs a first purge step and a second purge step in a sequential order;

[0010] The first purge step is to input the mixed gas into each of the adsorption towers through the mixed gas inlet pipeline; the second purge step is to input high-purity oxygen into each of the adsorption towers through the high-purity oxygen purge pipeline;

[0011] The total intake air volume of the first purge step is less than the total intake air volume of the second purge step;

[0012] The total air intake volume of the first purge step and the second purge step is sufficient so that when the pressure swing adsorption gas production reaches stability, the oxygen concentration of the mixed gas in a certain space near the end of each adsorption tower where the high-purity oxygen is extracted is not less than a first preset value within a certain time range;

[0013] The high-purity oxygen is a gas obtained by desorption through the pressure swing adsorption method, and its oxygen concentration is a second preset value; the first preset value is less than the second preset value.

[0014] Furthermore, the pressure swing adsorption oxygen purification device further comprises a high-purity oxygen storage tank;

[0015] The high-purity oxygen storage tank is connected to the high-purity oxygen outlet pipeline and the high-purity oxygen purge pipeline, and is used to collect the high-purity oxygen desorbed from one end of each adsorption tower away from the high-purity oxygen inlet, and input the high-purity oxygen into the high-purity oxygen purge pipeline for the second purge step.

[0016] Furthermore, the pressure swing adsorption oxygen purification device further comprises a first oxygen recovery tank and a purge gas recovery pipeline;

[0017] The purge gas recovery pipeline is connected to the adsorption tower, and the first oxygen recovery tank is connected to the purge gas recovery pipeline, and is used to collect the gas blown out in the first purge step and / or the second purge step, and is used for the production of the mixed gas.

[0018] Furthermore, the pressure swing adsorption oxygen purification device further comprises a second oxygen recovery tank and a purge gas recovery pipeline;

[0019] The purge gas recovery pipeline is connected to the adsorption tower, and the second oxygen recovery tank is connected to the purge gas recovery pipeline, which is used to collect the gas blown out in the first purge step and / or the second purge step, and directly input it into the adsorption tower as a mixed gas.

[0020] Furthermore, the pressure swing adsorption oxygen purification device further includes a regeneration air intake pipeline;

[0021] The regeneration air inlet pipeline is connected to the adsorption tower and is used to blow regeneration gas into the adsorption tower after desorption.

[0022] Furthermore, the pressure swing adsorption oxygen purification device further comprises:

[0023] In the mixed gas inlet pipeline, the oxygen concentration of the mixed gas input into the adsorption tower is 93-95%.

[0024] Furthermore, the pressure swing adsorption oxygen purification device further comprises:

[0025] The first preset value is 97%, so that the oxygen concentration in the gas desorbed by the pressure swing adsorption oxygen purification device is not less than 99.5%.

[0026] Furthermore, in the above-mentioned pressure swing adsorption oxygen purification device, the adsorption tower includes a first adsorption tower and a first adsorption tower; and also includes a pressure equalizing pipeline, the pressure equalizing pipeline connects the top of the first adsorption tower and the bottom of the second adsorption tower, and also connects the bottom of the first adsorption tower and the top of the second adsorption tower.

[0027] According to a second aspect of the present invention, there is also provided a pressure swing adsorption oxygen generator, characterized in that:

[0028] The invention at least comprises a general oxygen generator for producing 93% to 95% oxygen, and a pressure swing adsorption oxygen purification device as described in any one of the above items, which are connected in sequence.

[0029] Furthermore, the above-mentioned pressure swing adsorption oxygen generator further includes:

[0030] Before the pressure swing adsorption reaches a steady state, the gas purged in the first purge step and / or the gas purged in the second purge step are directly discharged.

[0031] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0032] The present invention provides a pressure swing adsorption oxygen purification device and a pressure swing adsorption oxygen generator. By using high-purity oxygen to purge the adsorption tower before desorbing oxygen, the impurity gas in the adsorption tower is blown away, which can effectively increase the oxygen concentration of pressure swing adsorption oxygen production. At the same time, the two-step purge method of first purging with mixed gas and then purging with high-purity oxygen can effectively save high-purity oxygen as a product. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 A schematic diagram of the structure of an oxygen purification device provided in Example 1 of the present invention;

[0035] Figure 2 A schematic diagram of the structure of an adsorption tower provided in Example 1 of the present invention;

[0036] Figure 3 A schematic structural diagram of another optional implementation of the oxygen purification device provided in Example 1 of the present invention;

[0037] Figure 4 A schematic diagram of the structure of an oxygen purification device provided in Example 2 of the present invention;

[0038] Figure 5 A schematic diagram of the structure of another oxygen purification device provided in Example 2 of the present invention;

[0039] Figure 6 A schematic diagram of the structure of a third oxygen purification device provided in Example 2 of the present invention;

[0040] Figure 7 A schematic structural diagram of a fourth oxygen purification device provided in Example 2 of the present invention;

[0041] Figure 8 A schematic diagram of a pressure equalizing pipeline in an oxygen purification device provided in Example 3 of the present invention;

[0042] Fig. 9 This is a schematic diagram of a pressure equalizing pipeline in another oxygen purification device provided in Example 3 of the present invention. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0044] The terms "first", "second", "third", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0045] Embodiment 1:

[0046] As the first embodiment of the present invention, an oxygen purification device is provided. A pressure swing adsorption oxygen generator that produces high-purity oxygen through a two-stage pressure swing adsorption system, the first-stage pressure swing adsorption system, also known as a general oxygen generator, uses air as a mixed gas, and absorbs nitrogen in the air through a balanced selective molecular sieve (such as a zeolite molecular sieve), and oxygen is discharged from the adsorption tower as a product gas. The gas obtained in this way is a mixed gas rich in oxygen, called general oxygen, and the oxygen content in general oxygen is usually 93% to 95%, and the rest is impurity gas, the main components of which are argon and a small amount of nitrogen. The general oxygen obtained by the first-stage pressure swing adsorption system will be temporarily stored in the first oxygen buffer tank. Figure 1 The general oxygen concentrator is not shown in the figure.

[0047] Second stage pressure swing adsorption system, such as Figure 1 As shown, it is called an oxygen purification device. It uses general oxygen as a mixed gas, and adsorbs oxygen in the general oxygen through a molecular sieve (usually a kinetically selective molecular sieve such as a carbon molecular sieve). The impurity gas is discharged from the adsorption tower as exhaust gas, usually directly discharged into the air. After the molecular sieve adsorption is completed, the oxygen is desorbed and extracted as desorbed gas. The desorbed gas is high-purity oxygen with an oxygen content of more than 99.5%.

[0048] The oxygen purification device provided in this embodiment is as follows: Figure 1 As shown, the oxygen purification device at least includes a first adsorption tower 1A, a second adsorption tower 1B, and a mixed gas intake pipeline 0 for the first adsorption tower 1A and the first adsorption tower 1B to intake air, and also includes an exhaust pipeline 7 for the first adsorption tower 1A and the first adsorption tower 1B to exhaust air. In addition, the oxygen purification device also includes Figure 1 The oxygen purification device also includes a high-purity oxygen outlet pipeline and a high-purity oxygen purge pipeline. The high-purity oxygen outlet pipeline is a pipeline controlled by valves 316 and 317, on which an oxygen compressor 4 is installed. Figure 1 In the figure, the high-purity oxygen purge pipeline is a pipeline controlled by valves 314 and 315.

[0049] In the adsorption tower of the above oxygen purification device, the molecular sieve adsorbs oxygen, and the unadsorbed gas is distributed in various spaces in the adsorption tower as impurity gas. During exhaust, most of the impurity gas will be discharged through the gas outlet of the adsorption tower. However, a small amount of impurity gas and unadsorbed mixed gas will still remain in the adsorption tower. A small amount of residual gas will be extracted as product gas along with the desorbed oxygen during the oxygen desorption process, and affect the final product gas concentration. Therefore, it is necessary to remove the residual impurity gas as much as possible.

[0050] In order to achieve the above objectives, in the oxygen purification device of this embodiment, each adsorption tower thereof needs to perform a first purge step and a second purge step in sequence during the conventional pressure swing adsorption process. The first purge step and the second purge step of the present invention are, in one embodiment, performed in sequence, and in one embodiment, are performed in sequence for multiple cycles, based on the actual concentration at the outlet and the equilibrium state of the pressure swing adsorption.

[0051] The first step is the first purge step. In this embodiment, the first purge step is to use the mixed gas to purge the molecular sieve bed of the adsorption tower. Figure 1 In the oxygen purification device shown, the method for achieving the first purge is to keep valve 312 open, so that the mixed gas enters the adsorption tower from the bottom end of the adsorption tower and purges the molecular sieve bed of the adsorption tower.

[0052] Next is the second purging step. In this embodiment, the second purging step is to use high-purity oxygen to enter from one end of the adsorption tower to purge the adsorption tower. This step can be controlled by a valve so that high-purity oxygen enters from one end of the adsorption tower, and after purging the adsorption tower, the purged mixed gas is discharged from the other end of the adsorption tower.

[0053] As an illustrative example, Figure 1 In the process, the adsorption tower 1A performs a second purge step, the control valve 314 is opened, and the high-purity oxygen in the high-purity oxygen storage tank 2 is refluxed into the adsorption tower 1A through the bottom end of the adsorption tower to perform a second purge step.

[0054] The pressure swing adsorption method used in the adsorption tower in this embodiment may also include a pressurization step, an exhaust step and a desorption step performed by a method known in the art. The purging method in this embodiment is applied after the pressurization step and the exhaust step and before the desorption step.

[0055] The pressure charging step of this embodiment is to pressurize the mixed gas and then charge it into the adsorption tower. As an optional method, the pressure charging step is usually achieved by adjusting the opening and closing of the valve. Figure 1 In the step of charging the adsorption tower 1A, the valve 312 is opened, and the compressor at the front end works to compress the mixed gas, which then passes through the mixed gas inlet pipeline 0 and enters the adsorption tower 1A through the lower end of the adsorption tower.

[0056] The exhaust step of this embodiment is to exhaust the gas adsorbed in the adsorption tower. Figure 1In the adsorption tower 1A, when the exhaust step is performed, valves 301 and 302 can be opened and other valves can be closed. After the mixed gas passes through the molecular sieve bed, the unadsorbed gas is discharged through the second exhaust pipeline 7 at the top of the adsorption tower 1A. In this embodiment, the exhaust step only needs to be performed before the second purge step begins, that is, the start time of the exhaust step can be synchronized with the pressurization step, can be slightly later than the start time of the pressurization step, and can also be performed in sequence after the pressurization is completed. When the exhaust step and the pressurization step overlap in time, the corresponding valves can be opened at the same time, for example, valves 312, 301 and 302 can be opened at the same time, so that the pressurization step and the exhaust step can be performed simultaneously.

[0057] The desorption step of this embodiment is to desorb the oxygen adsorbed by the molecular sieve in the adsorption tower as the desorbed gas. In the oxygen purification device in this embodiment, the desorbed gas is usually high-purity oxygen with an oxygen concentration of more than 99.5%, and this part of the desorbed gas is used as the product gas of the oxygen purification device. As an optional method, the desorption step in this embodiment is to use an oxygen compressor 4 to remove the oxygen adsorbed by the molecular sieve in the adsorption tower, and purge and regenerate it with the desorbed gas, that is, high-purity oxygen. The desorbed gas is pressurized by an oxygen booster and then stored in a high-purity oxygen storage tank 2.

[0058] After the desorption step, the adsorption tower can be purged with high-purity oxygen to further desorb and regenerate the molecular sieve in the adsorption tower. Figure 1 In the oxygen purification device shown in FIG. 1 , the regeneration air inlet line 5 is connected to high-purity oxygen, and is used to blow high-purity oxygen into the adsorption tower after desorption and at a lower pressure to achieve complete desorption of the molecular sieve in the adsorption tower. In some embodiments, the high-purity oxygen used for regeneration is the high-purity oxygen for desorption. In other embodiments, desorption regeneration can also be performed by blowing in other gases.

[0059] In this embodiment, the purpose of the first purge step is to blow away the impurity gas inside the adsorption tower and outside the molecular sieve, and the second purge step is to blow away the mixed gas remaining in the adsorption tower, thereby further increasing the oxygen concentration in the overall space inside the adsorption tower. Therefore, the total amount of purges in the first purge step and the second purge step is the key to achieving this effect.

[0060] If the total amount of gas used for purging is too small, the molecular sieve bed and its two ends cannot be purged effectively, the purging effect is poor, and the concentration of the desorbed gas is affected. If the total amount of gas used for purging is too large, it will cause waste. Therefore, it is necessary to accurately control the total amount of purging gas.

[0061] Based on this, the present embodiment also needs to be designed as follows. For ease of explanation, the adsorption tower is divided into three spaces according to the position of the molecular sieve bed in the present embodiment, including the molecular sieve bed and the first end and the second end located on both sides of the molecular sieve bed. Figure 2 For example, Figure 2 Shows Figure 1 The first end of the adsorption tower is the lower end of the molecular sieve bed inside the adsorption tower, i.e. Figure 2 The space shown in the 101 section. Figure 2 The 102 in the figure is the space where the molecular sieve bed is located. The second end of the adsorption tower is the interior of the adsorption tower and the upper end of the molecular sieve bed, i.e. Figure 2 The space shown in section 103.

[0062] First, consider the source of high-purity oxygen. In this embodiment, since the gas obtained by desorption is the high-purity product oxygen for output, its oxygen concentration is designed to be 99% or 99.5%. Therefore, directly using the high-purity oxygen obtained by desorption for purging is the simplest way. This embodiment adopts a high-purity oxygen purge pipeline, and the high-purity oxygen obtained by desorption is first stored in a high-purity oxygen storage tank 2, and then input from the high-purity oxygen storage tank 2 into the adsorption tower for purging. The oxygen concentration of the mixed gas obtained by desorption is called the second preset value, which is 99.5% in this embodiment.

[0063] As another optional implementation, Figure 3 As shown, the mixed gas obtained by desorption from another adsorption tower that is producing gas can also be used as high-purity oxygen for the second purge step. For example, when the adsorption tower 1A needs to be purged with high-purity oxygen, the high-purity oxygen produced by desorption from the adsorption tower 1B can be opened by opening valves 314 and 315 so that the high-purity oxygen produced by desorption from the adsorption tower 1B flows into the bottom end of the adsorption tower 1A, thereby achieving the second purge step. In this embodiment, the high-purity oxygen purge pipeline is a pipeline controlled by valves 314 and 315.

[0064] Consider the total air intake of the first purge and the second purge. Since the purpose of the purge is to increase the concentration of oxygen in the mixed gas obtained by desorption, and the mixed gas obtained by desorption is not required to be 100% oxygen, the purpose of the second purge step implemented later is not to completely discharge the residual mixed gas and a very small amount of impurity gas. For example, if the oxygen concentration obtained by desorption is expected to be 99.5%, then 0.5% of other gases are still allowed to remain in the adsorption tower.

[0065] Furthermore, in the second purge step, high-purity oxygen is introduced through one end of the adsorption tower, which will cause the impurity gas in the adsorption tower to be accumulated in a certain range of space close to the high-purity oxygen extraction end along the purge direction. Therefore, as long as the oxygen concentration in the mixed gas in the space close to the high-purity oxygen extraction end of the adsorption tower is measured, the oxygen concentration of the mixed gas obtained by desorption can be calculated.

[0066] For example, according to Figure 1In the oxygen purification device shown, the bottom end 101 of the adsorption tower is used as the inlet end of the high-purity oxygen in the second purge step, and the end for measuring the oxygen concentration is the top end 103 of the adsorption tower. When the oxygen concentration reaches a certain preset value in a space close to the adsorption tower and away from the high-purity oxygen extraction inlet end, i.e., the end 103, the purge is considered to have achieved the effect and the next step can be performed. In this embodiment, this preset value is called the first preset value.

[0067] Further consider the relationship between the first preset value and the second preset value. Figure 2 As shown, at the bottom end 101 of the adsorption tower, after the second purge step, only high-purity oxygen will exist in this part, and other gases remaining in the previous steps will be purged to the molecular sieve bed and the gas outlet of the adsorption tower by high-purity oxygen. Therefore, the oxygen concentration of this part is equal to the oxygen concentration of high-purity oxygen. In the molecular sieve bed 102, after the second purge step, this part of the gas can be considered as a mixed gas of oxygen and high-purity oxygen adsorbed by the molecular sieve. Even if a small amount of impurity gas may be adsorbed in the molecular sieve (for example, a carbon molecular sieve may adsorb a small amount of argon or nitrogen), the content of these impurity gases is very small and has little effect on the oxygen concentration of this part of the mixed gas. Therefore, the oxygen concentration of this part can be considered as the concentration after 100% oxygen and high-purity oxygen are mixed, which will be greater than the oxygen concentration of high-purity oxygen. At the top end 103 of the adsorption tower, after the second purge step, there will be a small amount of mixed gas, a part of high-purity oxygen and a very small amount of impurity gas in this space. Therefore, the oxygen concentration in this space will be lower than the concentration of high-purity oxygen. Finally, in the desorption step, the oxygen concentration of the gas in the entire adsorption tower is determined by the ratio of the oxygen concentrations in the three spaces.

[0068] When the first preset value is greater than the second preset value, the gas concentration of oxygen in the molecular sieve bed part and the high-purity oxygen inlet end space will be greater than the second preset value. At this time, the oxygen concentration of the mixed gas obtained by desorption will definitely be greater than the second preset value. In this case, the oxygen concentration of the mixed gas obtained by desorption will continue to increase. This situation is common in the state when the oxygen purification device is just started. When the first preset value is less than the second preset value, according to the previous analysis, the oxygen concentration of the mixed gas desorbed and extracted from the three parts of the adsorption tower is determined by the ratio of the oxygen concentrations in the three spaces. Therefore, the concentration of the desorbed gas can also reach the second preset value at this time. This situation is common in the case when the pressure swing adsorption reaches a stable state in the oxygen purification device, which can achieve continuous and stable production of a mixed gas with an oxygen concentration of the second preset value.

[0069] Further consider the specific value of the first preset value. Usually, the space left at the first end and the second end of the adsorption tower is relatively small, and most of them are used for the installation of pipe fittings and molecular sieve mounting orifice plates. Taking the common case where the first end and the second end account for a total of 10% of the volume of the adsorption tower, the average oxygen concentration of the high-purity oxygen and adsorbed gas in the molecular sieve bed is calculated as 99.8%, and the first preset value can be preliminarily calculated to be approximately 95%. Further considering the influence of the residual gas in the pipeline in each step, the first preset value is set to more than 97%, which is usually sufficient to ensure that the oxygen concentration in the mixed gas obtained by desorption under most conditions can reach 99.5%.

[0070] After the total air intake volume of the purge is determined according to the above method, the air intake volumes of the first purge step and the second purge step are further considered. Compared with the second purge step, the first purge step may also cause impurity gases to enter the molecular sieve, which will reduce the concentration of the desorbed gas. Therefore, in this embodiment, the air intake volume of the mixed gas in the first purge step is limited to not exceed the air intake volume of high-purity oxygen in the second purge step. Considering that the air intake volume is the product of the air intake time and the air intake rate, the total air intake volume can be flexibly controlled by controlling the air intake time and / or the air intake rate.

[0071] In this embodiment, the following method is provided to specifically operate the oxygen purification device.

[0072] As an optional specific implementation method, first, during the design phase of the entire oxygen purification device, the time required for each step is estimated, and after assembly, a factory test is performed to fine-tune the time required for each step, and the result is fixed in the control software of the oxygen purification device.

[0073] Specifically, through the structure of the adsorption tower design, the space size of the first end, the second end, and the molecular sieve bed of the adsorption tower is calculated. Further, considering that the air inlet end of the high-purity oxygen is the first end or the second end, the size of the first preset value can be preliminarily estimated. Further, the air intake rate of the mixed gas and high-purity oxygen is designed as needed. For example, the air intake rate of the high-purity oxygen and the mixed gas can be designed to be a unified fixed value. Finally, the time ratio of the first purge time and the second purge time is determined, for example, m:n.

[0074] After the entire oxygen purification device is assembled, the oxygen concentration in the space at the end of the adsorption tower away from the high-purity oxygen inlet and the oxygen concentration in the desorbed gas are actually measured, and the time of the first purge step and the second purge step can be adjusted synchronously according to the above ratio of m:n. For the detection of oxygen concentration in the mixed gas in the space at the end of the adsorption tower away from the high-purity oxygen inlet, a gas concentration detection device can be set at any position on the pipeline directly connected to the end of the adsorption tower away from the high-purity oxygen inlet. After the oxygen purification device completes the above test and adjusts the opening and / or switching time of each valve, it is usually not necessary to adjust it again during subsequent normal use.

[0075] In the above embodiment, the intake rates of the first purge step and the second purge step may be different. If the rates are different, the time ratio also needs to be adjusted to ensure that the intake amount of the mixed gas does not exceed the intake amount of high-purity oxygen.

[0076] As another optional implementation, accurate control can be achieved through real-time monitoring and feedback adjustment. Specifically, a gas concentration detection device can be set at any position on the pipeline directly connected to the top of the adsorption tower, and the detection result of the detection device is connected to the control system of the oxygen purification device. The control system of the oxygen purification device will adjust the opening and / or on-off time of the corresponding valve in real time according to the detected gas concentration.

[0077] Considering that the concentration of oxygen in the desorbed mixed gas is constantly changing when the oxygen purification device is just started, the description of the oxygen concentration in the mixed gas in the space far away from the high-purity oxygen inlet end of the adsorption tower in this embodiment is a description when the pressure swing adsorption gas production reaches stability. In the present invention, the pressure swing adsorption gas production reaches stability, which means that the concentration of oxygen in the mixed gas desorbed by the oxygen purification device is stable within a certain range and no longer changes dramatically, that is, it does not include the state when the desorbed gas concentration changes dramatically when the device is just started, that is, the difference in the preset value of the oxygen concentration at this time, within a certain time range, continues to be executed after the first purge step and the second purge step, and the oxygen concentration value in a certain range of space at the oxygen extraction end reaches stability, and the certain time range is, for example, 20min to 40min.

[0078] Embodiment 2:

[0079] The oxygen purification device provided in this embodiment is based on the embodiment 1, and further considers a device for treating the purged mixed gas. Figure 1-Figure 3 In the structure of the oxygen purification device shown, a purge gas recovery pipeline 6 for recovering the purge gas is also reserved. In this embodiment, two methods for recovering the purge gas are provided, respectively: Figure 4 and Figure 5 shown.

[0080] Figure 4 The two-stage pressure swing adsorption oxygen generator described in Example 1 is shown, including a first-stage pressure swing adsorption system 001, i.e., the oxygen generator part, and a second-stage pressure swing adsorption system, i.e., the oxygen purification device part provided in this embodiment. Figure 4 In the illustrated embodiment, a first oxygen recovery tank 601 is provided after the purge gas recovery pipeline 6, and the first oxygen recovery tank 601 collects the purge gas again and enters the first-stage pressure swing adsorption system as the purge regeneration gas of the first-stage pressure swing adsorption system. That is, in the first-stage pressure swing adsorption system, after the molecular sieve adsorbs nitrogen, the molecular sieve can be purged and regenerated with the mixed gas blown out in the first purge and second purge steps. This arrangement can effectively reduce the oxygen consumption and improve the oxygen recovery rate of the entire pressure swing adsorption oxygen generator.

[0081] Figure 5 The oxygen purification device portion of the two-stage pressure swing adsorption oxygen generator described in Example 1 is shown. Figure 5 In the illustrated embodiment, a second oxygen recovery tank 602 is provided on the purge gas recovery pipeline 6 to temporarily store this part of the mixed gas, and as a mixed gas, it enters the oxygen purification device again. This arrangement can effectively reduce the oxygen consumption, and the oxygen purification device and the general oxygen generator work independently of each other. The general oxygen generator does not rely on the mixed gas generated by the oxygen purification device as regeneration gas, and can realize the modular production of the oxygen purification device and the general oxygen generator, that is, the oxygen purification device of this embodiment can be applied to the rear end of various other general oxygen generators, which is convenient for the production and assembly of the entire pressure swing adsorption oxygen generator.

[0082] The above method uses the same pipeline to output the gas blown out by the first purge and the second purge, which is a relatively simple and easy-to-implement recovery method. Those skilled in the art can also recover the gas generated in the first purge and the second purge separately, such as Figure 6 , Figure 7 Multiple oxygen recovery tanks are set up for use in different occasions.

[0083] The oxygen purification device part in this embodiment can be implemented in the manner described in Example 1, and the general oxygen generator part can be implemented using the technology of oxygen-nitrogen separation pressure swing adsorption oxygen generator such as the common common sense technology.

[0084] Embodiment 3:

[0085] The oxygen purification device provided in this embodiment is based on Embodiment 1 or 2, and a pressure equalizing pipeline is added.

[0086] As a preferred method, the pressure equalizing pipeline in this embodiment is shown in Figure 8, is a pipeline controlled by valves 310 and 311. The pressure equalization pipeline connects the second end of the adsorption tower to the first end of another adsorption tower for cross-pressure equalization. By means of cross-pressure equalization, the mixed gas accumulated at the first end or the second end of the adsorption tower after the second purge can be adsorbed and purified again by another adsorption tower, which can effectively improve the adsorption rate. As another optional method, the pressure equalization method in this embodiment can also be referred to Fig. 9 The second ends of the two adsorption towers are connected to each other and the first ends of the two adsorption towers are connected to each other through the control of valve 312, valve 313, valve 308, and valve 309, and no additional pressure equalization pipeline is required. The present invention can also be used, but not limited to, as shown in the attached Figure 8 or attached Fig. 9 The pressure equalization method is a pressure equalization method known in the art. A skilled technician can arbitrarily adopt and design any pressure equalization method known in the art to achieve similar effects. The remaining steps of this embodiment can refer to embodiment 1 or 2, and will not be repeated here.

[0087] Embodiment 4:

[0088] This embodiment provides a pressure swing adsorption oxygen generator, which includes a two-stage pressure swing adsorption structure, wherein the first stage pressure swing adsorption structure uses air as a raw material, adsorbs nitrogen through a molecular sieve, separates nitrogen from oxygen, and obtains oxygen with a concentration of 93% to 95%. The second stage pressure swing adsorption structure uses an oxygen purification device as in any one of embodiments 1 to 3 to achieve the production of oxygen with a concentration of 99.5%.

[0089] In order to better describe the present invention, some terms and some implementation methods of the present invention are explained as follows.

[0090] In the present invention, the mixed gas refers to the gas that enters the pressure swing adsorption device as a raw material. For example, in the oxygen purification device of Example 1, the mixed gas is the general oxygen produced by the previous general oxygen generator, which includes 93% to 95% oxygen, and the remaining components are mainly nitrogen and argon. In other embodiments, the mixed gas can also be other gases, such as air.

[0091] The pressure swing adsorption process is to separate the mixed gas by using molecular sieves to have different adsorption effects on different gases, with strong adsorption effects on some gases and weak adsorption effects on other gases. Pressure swing adsorption also requires desorption of the gas adsorbed by the molecular sieve, so that the molecular sieve can be recycled. Therefore, based on the principle of pressure swing adsorption, in the present invention, the gases after pressure swing adsorption are respectively referred to as exhaust gas and desorbed gas.

[0092] Exhaust gas refers to the gas that the molecular sieve has a weaker adsorption effect on, which may be a single gas or a mixture of multiple gases. Desorbed gas refers to the gas that the molecular sieve has a stronger adsorption effect on, and the gas obtained by desorption after the molecular sieve adsorbs, which may also be a single gas or a mixture of multiple gases.

[0093] In the present invention, the target gas is a gaseous substance in a chemical sense, for example, the target gas may be oxygen.

[0094] In the present invention, unless otherwise specified, "concentration" and "purity" have the same meaning, that is, the volume fraction percentage of a specific gas element in a mixed gas.

[0095] In the present invention, there is no need to specifically limit the gas flow rate in each step, and it can be specifically controlled according to the method described in the above embodiment and combined with the needs of the corresponding device. That is, the present invention is not specifically limited to the gas rate control in the pressure swing adsorption method, and a low flow rate scheme or a high flow rate scheme can be adopted as needed.

[0096] In the present invention, the adsorption tower may also be referred to as an adsorber, an adsorption bed, etc., and is a container filled with a molecular sieve or an adsorbent for adsorption. Its shape and appearance may not be limited to the common tower type, but may also be a horizontal type or any other shape and appearance that can be used for pressure swing adsorption.

[0097] In the above embodiments, a tower-type adsorption tower is used as an illustration, and the bottom end of the adsorption tower is used as the air inlet end, and the top end of the adsorption tower is used as the air outlet end. Those skilled in the art may also set the air inlet end to the top end of the adsorption tower and the air outlet end to the bottom end of the adsorption tower as needed. As another optional method, the air inlet end and the air outlet end of each step may be exchanged or arranged and combined to realize the technical solution of the present invention.

[0098] In the above embodiment, the adsorption tower is divided into three space parts, the first end is the bottom space, the second end is the top space, and the molecular sieve bed space between the first end and the second end. The specific structure of the first end, the second end and the molecular sieve bed of the adsorption tower in the present invention is not limited to the segmentation method in the above embodiment. For example, as an optional embodiment, the adsorption tower can also be divided into three space parts in the horizontal direction, with the first end on the left, the second end on the right, and the molecular sieve bed in the middle. This setting is still applicable to the pressure swing adsorption method provided in the above embodiment. The setting of the adsorption tower and the molecular sieve bed of the present invention is not limited to the above embodiment. It is only necessary to divide the adsorption tower into three parts in the adsorption tower as described in Example 1. At the same time, the first end and the second end of the adsorption tower can not only include the parts on both sides of the molecular sieve bed in the adsorption tower, but also include the space in the pipeline connected to this end of the adsorption tower and directly connectable. For example, if the structure of the adsorption tower is small and the diameter of the pipeline connected to it is large, the space in the pipeline should also be included in the consideration range of the calculation of the first end and the second end.

[0099] Considering that there may be two types of gas intake and two types of gas outlet requirements at both ends of the adsorption tower, the intake includes mixed gas and high-purity oxygen, and the outlet includes gas directly discharged into the air and gas recycled and reused. Therefore, the structure of the adsorption tower can be set to have a pipeline at each end, and then a structure similar to a three-way or switchable valve is set on the pipeline to achieve mutual switching of multiple types of inlet and outlet structures. Or directly set multiple inlet / outlet pipelines at both ends of the adsorption tower, and set the function of each pipeline according to the needs. Those skilled in the art can also make settings according to the above settings as needed.

[0100] In the present invention, molecular sieve refers to a material used for adsorption that has different adsorption effects on different gases, and may also be called an adsorbent, adsorption material, etc.

[0101] In the present invention, "pressure swing adsorption" includes but is not limited to atmospheric pressure swing adsorption, vacuum pressure swing adsorption and / or mixed pressure swing / temperature swing adsorption. Specifically, any method that can make the molecular sieve adsorb a certain gas under high pressure and desorb the gas under low pressure is included in the scope of "pressure swing adsorption" described in the present invention.

[0102] The pressure swing adsorption method described in the present invention is a pressure swing adsorption method for one of the adsorption towers. In a conventional double-tower pressure swing adsorption system, the two adsorption towers usually work asynchronously. In a structure of three, four or more adsorption towers, the step sequence differences between the adsorption towers can be redesigned according to the prior art or designed according to actual needs, which will not be repeated here.

[0103] The pressure swing adsorption method or adsorption tower described in the present invention does not make specific requirements for the type of specific molecular sieve in the adsorption tower. For example, in the above-mentioned embodiment involving an oxygen generator, those skilled in the art can select common zeolite molecular sieves as the molecular sieve of the general oxygen generator, and select carbon molecular sieves as the molecular sieve of the oxygen purification device. For another example, those skilled in the art can also select silver-loaded zeolite molecular sieves as the molecular sieve of the oxygen purification device. The specific model selection of the molecular sieve, such as the pore size of the molecular sieve, etc., are all routine choices that those skilled in the art can make according to the needs of implementing the steps of the above-mentioned embodiments.

[0104] In the present invention, the pressurization step, exhaust step and desorption step are all schematic steps. Those skilled in the art will understand that the above-mentioned effects can be achieved by other methods known in the art, which can be applied to the present invention by conversion. For example, in the desorption step, a common desorption regeneration method is recorded in Example 1, which is to purge and regenerate the adsorption tower through the regeneration pipeline 5 with a high concentration of the first gas. Those skilled in the art may also choose other purge regeneration methods known in the art to purge and regenerate the molecular sieve. Furthermore, in addition to the above-mentioned limited steps, those skilled in the art may also add new steps as needed, which will not be repeated here.

[0105] It should be noted that, for the above-mentioned method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the described action sequence, because according to the present invention, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present invention.

[0106] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0107] The above is only an exemplary embodiment of the present disclosure, and the scope of the present disclosure cannot be limited thereto. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the specification and practicing the disclosure here, those skilled in the art will easily think of the implementation scheme of the present disclosure. The present invention is intended to cover any variation, use or adaptive change of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the technical field not recorded in the present disclosure. The description and examples are regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.

[0108] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0109] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A pressure swing adsorption oxygen purification device, characterized in that: It includes several adsorption towers; Each of the adsorption towers comprises a mixed gas inlet pipeline and an exhaust pipeline; Each of the adsorption towers also includes a high-purity oxygen outlet pipeline and a high-purity oxygen purge pipeline; Wherein, after exhausting, each adsorption tower performs a first purge step and a second purge step in a sequential order; The first purge step is to input the mixed gas into each of the adsorption towers through the mixed gas inlet pipeline; the second purge step is to input high-purity oxygen into each of the adsorption towers through the high-purity oxygen purge pipeline; The total intake air volume of the first purge step is less than the total intake air volume of the second purge step; The total air intake volume of the first purge step and the second purge step is sufficient so that when the pressure swing adsorption gas production reaches stability, the oxygen concentration of the mixed gas in a certain space near the end of each adsorption tower where the high-purity oxygen is extracted is not less than a first preset value within a certain time range; The high-purity oxygen is a gas obtained by desorption through the pressure swing adsorption method, and its oxygen concentration is a second preset value; the first preset value is less than the second preset value.

2. The pressure swing adsorption oxygen purification device according to claim 1, characterized in that: It also includes high-purity oxygen storage tanks; The high-purity oxygen storage tank is connected to the high-purity oxygen outlet pipeline and the high-purity oxygen purge pipeline, and is used to collect the high-purity oxygen desorbed from one end of each adsorption tower away from the high-purity oxygen inlet, and input the high-purity oxygen into the high-purity oxygen purge pipeline for the second purge step.

3. The pressure swing adsorption oxygen purification device according to claim 1, characterized in that: Also included is a first oxygen recovery tank and a purge gas recovery pipeline; The purge gas recovery pipeline is connected to each of the adsorption towers, and the first oxygen recovery tank is connected to the purge gas recovery pipeline, and is used to collect the gas blown out in the first purge step and / or the second purge step, and is used for the production of the mixed gas.

4. The pressure swing adsorption oxygen purification device according to claim 1, characterized in that: Also included is a second oxygen recovery tank and a purge gas recovery pipeline; The purge gas recovery pipeline is connected to the adsorption tower, and the second oxygen recovery tank is connected to the purge gas recovery pipeline, which is used to collect the gas blown out in the first purge step and / or the second purge step, and directly input it into the adsorption tower as a mixed gas.

5. The pressure swing adsorption oxygen purification device according to claim 1, characterized in that: Also included is a regenerative air intake line; The regeneration air inlet pipeline is connected to the adsorption tower and is used to blow regeneration gas into the adsorption tower after desorption.

6. The pressure swing adsorption oxygen purification device according to claim 1, characterized in that: In the mixed gas inlet pipeline, the oxygen concentration of the mixed gas input into the adsorption tower is 93-95%.

7. The pressure swing adsorption oxygen purification device according to claim 6, characterized in that: The first preset value is 97%, so that the oxygen concentration in the gas desorbed by the pressure swing adsorption oxygen purification device is not less than 99.5%.

8. The pressure swing adsorption oxygen purification device according to claim 1, characterized in that: The adsorption tower includes a first adsorption tower and a second adsorption tower; and also includes a pressure equalizing pipeline, which connects the top of the first adsorption tower and the bottom of the second adsorption tower, and also connects the bottom of the first adsorption tower and the top of the second adsorption tower.

9. A pressure swing adsorption oxygen generator, characterized in that: The invention at least comprises a general oxygen generator for producing 93% to 95% oxygen, and a pressure swing adsorption oxygen purification device as claimed in any one of claims 1 to 8, which are connected in sequence.

10. The pressure swing adsorption oxygen generator according to claim 9, characterized in that: Before the pressure swing adsorption reaches a steady state, the gas purged in the first purge step and / or the gas purged in the second purge step are directly discharged.

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