Purging method, pressure swing / temperature swing adsorption method and device and storage medium

Abstract

The invention discloses a purging method which is applied to a pressure swing / temperature swing adsorption method, and the pressure swing / temperature swing adsorption method acts on mixed gas and is used for adsorbing target gas in the mixed gas and then desorbing the target gas. The purging method is characterized by comprising a first purging step and a second purging step which are carried out in sequence, a first purging step: purging the adsorption tower by using the mixed gas; in the second purging step, high-purity gas enters the adsorption tower from one end of the adsorption tower to purge the adsorption tower; the total air inflow of the first purging step is smaller than the total air inflow of the second purging step; the total time of the first purging step and the second purging step is long enough, so that the target gas concentration of the mixed gas in the space, far away from the high-purity gas inlet end, of the adsorption tower is not less than a first preset value when the variable-pressure / variable-temperature adsorption cycle is stable. According to the invention, the concentration of the target gas in the desorption gas can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure swing / temperature swing adsorption, and more specifically, to a purging method, a pressure swing / temperature swing adsorption method, a pressure swing / temperature swing adsorption device and a storage medium. Background Art

[0002] After years of development, the pressure swing / temperature 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 the pressure swing / temperature 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 the cryogenic method or other chemical methods, the pressure swing / temperature swing adsorption technology has many advantages such as simple structure, good reliability, low cost, and high efficiency.

[0003] In the prior art, there is a technical solution that utilizes the principle of pressure swing / temperature swing adsorption to adsorb the target gas and then desorb it as the product gas. However, this type of technical solution is often difficult to obtain high-purity desorbed gas in practical applications. Summary of the invention

[0004] In response to at least one defect or improvement need in the prior art, the present invention provides a purging method, a pressure swing / temperature swing adsorption method, a pressure swing / temperature swing adsorption device and a storage medium, which can effectively increase the concentration of the target gas in the desorbed gas of the pressure swing / temperature swing adsorption.

[0005] To achieve the above object, according to a first aspect of the present invention, a purging method is provided, which is applied to a pressure swing / temperature swing adsorption method, wherein the pressure swing / temperature swing adsorption method acts on a mixed gas to adsorb a target gas therein and then desorb the target gas to separate the target gas from the mixed gas; characterized in that:

[0006] The purge method is applied after the exhaust step and before the desorption step;

[0007] The purging method comprises a first purging step and a second purging step performed in a sequential order;

[0008] The first purging step is to purge the adsorption tower with the mixed gas; the second purging step is to purge the adsorption tower with high purity gas entering from one end of the adsorption tower;

[0009] The total air intake volume of the first purge step is less than the total air intake volume of the second purge step;

[0010] The total time of the first purging step and the second purging step is long enough so that when the pressure swing / temperature swing adsorption gas production reaches stability, the target gas concentration of the mixed gas in the space at the end of the adsorption tower away from the high purity gas inlet is not less than the first preset value;

[0011] Among them, the high-purity gas is a mixed gas containing a target gas, and the concentration of the target gas in the high-purity gas is not less than a second preset value, and the second preset value is the concentration of the target gas in the gas desorbed by the pressure / temperature swing adsorption method; the first preset value is less than the second preset value.

[0012] Furthermore, the above-mentioned purging method further comprises:

[0013] There is a first difference between the first preset value and the second preset value.

[0014] Furthermore, the above-mentioned purging method further comprises:

[0015] The first difference decreases as the second preset value increases.

[0016] Furthermore, the above-mentioned purging method further comprises:

[0017] The high-purity gas is the gas desorbed by the pressure swing / temperature swing adsorption method, or a mixed gas containing a high-purity target gas from an external source.

[0018] Furthermore, the above-mentioned purging method further comprises:

[0019] The gas purged out in the first purging step and / or the gas purged out in the second purging step is recovered and then fed into the adsorption tower as a mixed gas.

[0020] Furthermore, the above-mentioned purging method further comprises:

[0021] The gas purged out in the first purging step and / or the gas purged out in the second purging step are recovered and used for the production of the mixed gas.

[0022] According to the second aspect of the present invention, there is also provided a pressure swing / temperature swing adsorption method for separating a target gas from a mixed gas, wherein after adsorbing the target gas, the pressure swing / temperature swing adsorption method obtains a mixed gas rich in the target gas by desorption, and is characterized in that the pressure swing / temperature swing adsorption method at least includes, on an adsorption tower, after an exhaust step, implementing a purge method as described in any one of the above items, and then implementing a desorption step.

[0023] Furthermore, the above-mentioned pressure swing / temperature swing adsorption method further comprises:

[0024] The method further comprises a pressure equalization step, wherein the pressure equalization step is performed by cross pressure equalization before the desorption step.

[0025] According to the third aspect of the present invention, there is also provided a pressure swing / temperature swing adsorption device, characterized in that it comprises at least one processing unit and at least one storage unit, wherein the storage unit stores a computer program, and when the computer program is executed by the processing unit, the processing unit drives the pressure swing / temperature swing adsorption device to perform the steps of any of the methods described above.

[0026] According to a fourth aspect of the present invention, there is also provided a computer-readable storage medium, characterized in that it stores a computer program, which, when executed by a processor, drives the pressure swing / temperature swing adsorption device to perform the steps of any of the methods described above.

[0027] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0028] The purging method provided by the present invention can effectively increase the concentration of the target gas in the desorbed gas by purging the adsorption tower with high-purity gas before desorbing the target gas, and blowing away the impurity gas in the adsorption tower. At the same time, the two-step purging method of first purging with mixed gas and then purging with high-purity gas can effectively save the high-purity gas as the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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.

[0030] Figure 1 A schematic diagram of the structure of an oxygen purification host provided in Example 1 of the present invention;

[0031] Figure 2 A schematic diagram of the structure of an adsorption tower provided in Example 1 of the present invention;

[0032] Figure 3 A schematic structural diagram of another optional implementation of the oxygen purification host provided in Example 1 of the present invention;

[0033] Figure 4 A schematic diagram of the structure of a pressure swing / temperature swing adsorption oxygen generator provided in Example 2 of the present invention;

[0034] Figure 5 A schematic diagram of the structure of another pressure swing / temperature swing adsorption oxygen generator provided in Example 2 of the present invention;

[0035] Figure 6 A schematic diagram of the structure of a third pressure swing / temperature swing adsorption oxygen generator provided in Example 2 of the present invention;

[0036] Figure 7 A schematic structural diagram of a fourth pressure swing / temperature swing adsorption oxygen generator provided in Example 2 of the present invention;

[0037] Figure 8 A schematic diagram of a pressure equalization method in a pressure swing / temperature swing adsorption method provided in Example 3 of the present invention;

[0038] Fig. 9 A schematic diagram of a pressure equalization method in another pressure swing / temperature swing adsorption method provided in Example 3 of the present invention. DETAILED DESCRIPTION

[0039] 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.

[0040] 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.

[0041] Embodiment 1:

[0042] As a first embodiment of the present invention, a purging method is provided, which is applied to Figure 1-3 The oxygen purification host in the pressure swing adsorption oxygen concentrator is shown.

[0043] The pressure swing adsorption oxygen generator produces high-purity oxygen through a two-stage pressure swing adsorption system. The first-stage pressure swing adsorption system, also known as the general oxygen generator, uses air as a mixed gas. It absorbs nitrogen in the air through a balanced selective molecular sieve (such as a zeolite molecular sieve), and the 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. The oxygen content in general oxygen is usually 93% to 95%, and the rest is impurity gas. The main components of the impurity gas 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.

[0044] Second stage pressure swing adsorption system, such as Figure 1 As shown, it is called the oxygen purification host, which uses general oxygen as the mixed gas, and adsorbs the oxygen in the general oxygen through a kinetic 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%. Figure 1 The oxygen purification main unit shown includes a first adsorption tower 1A, a second adsorption tower 1B, a high-purity oxygen storage tank 2, a number of valves (reference numerals 301 to 317) and an oxygen compressor 4. Figure 1 Also shown is the mixed gas inlet end 0 of the oxygen purification main unit, the regeneration inlet pipeline 5 for regenerating the adsorption tower in the oxygen purification main unit, and the outlet pipeline 6 of the mixed gas purged in the first purge step and the second purge step.

[0045] The purging method of this embodiment is applied to Figure 1 The oxygen purification host part is shown. For the convenience of description and understanding, the target gas in this embodiment is oxygen, and the mixed gas refers to the intake gas of the oxygen purification host, that is, general oxygen. The desorbed gas refers to the product gas of the oxygen purification host, that is, high-purity oxygen.

[0046] In the adsorption tower of the above oxygen purification host, 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, there will still be a small amount of impurity gas and unadsorbed mixed gas remaining 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.

[0047] In order to achieve the above objectives, this embodiment designs a purge method for each adsorption tower in the oxygen purification host, which is combined with the traditional pressure swing adsorption process, including a first purge step and a second purge step performed in sequence.

[0048] 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 On the oxygen purification main unit shown, the method for implementing 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.

[0049] 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.

[0050] As an illustrative example, Figure 1 In the process, the adsorption tower 1A performs the second purge step, the control valve 314 is opened, and the product gas of the oxygen purification host, that is, high-purity oxygen, is used as the high-purity gas, and the high-purity oxygen is refluxed into the adsorption tower 1A through the bottom end of the adsorption tower to perform the second purge step.

[0051] 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.

[0052] 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 pressurizing the adsorption tower 1A, the valve 312 is opened, and the compressor at the front end is operated to compress the mixed gas and then enter the adsorption tower 1A through the lower end of the adsorption tower.

[0053] The exhaust step of this embodiment is to exhaust the gas adsorbed in the adsorption tower. Figure 1 In the embodiment, when the adsorption tower 1A performs the exhaust step, the 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 top of the adsorption tower 1A. In this embodiment, the exhaust step only needs to be performed before the start of the second purge step, that is, the start time of the exhaust step can be synchronized with the pressurizing step, can be slightly later than the start time of the pressurizing step, or can be performed in sequence after the pressurizing step is completed. When the exhaust step and the pressurizing 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 pressurizing step and the exhaust step can be performed simultaneously.

[0054] 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 host of this embodiment, the desorbed gas is usually high-purity oxygen with an oxygen concentration of more than 99.5%. This part of the desorbed gas is used as the product gas of the oxygen purification host. 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 stored in a high-purity oxygen storage tank after the pressure is increased by an oxygen booster.

[0055] In the purging method of this embodiment, the purpose of the first purging step is to blow away the impurity gas in the adsorption tower and outside the molecular sieve, and the second purging step is to blow away the mixed gas remaining in the adsorption tower, thereby further increasing the oxygen concentration in the overall space in the adsorption tower. Therefore, in the entire purging method, the total amount of purging in the first purging step and the second purging step is the key to achieving this effect.

[0056] If the total amount of gas used for purging is too small, the molecular sieve bed and its two ends cannot be effectively purged, 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. Considering that the total amount of purging gas is the product of the intake rate and time, the total purging time of the purging method should be long enough so that the total amount of purging gas meets the requirements.

[0057] 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.

[0058] First, consider the concentration of the target gas in the high-purity gas. In the present embodiment, the high-purity gas is a mixed gas, and the high-purity gas contains a certain concentration of the target gas. In the present embodiment, it is necessary to use a pressure swing adsorption method to adsorb the target gas and then desorb it to obtain a mixed gas containing the target gas. Through the pressure swing adsorption method, in the mixed gas obtained by desorption, the concentration value of the target gas is defined as a second preset value. Taking the second preset value as the standard, the concentration of the target gas in the high-purity gas should not be lower than the second preset value. For example, in the pressure swing adsorption method in the present embodiment, if the oxygen concentration obtained by desorption is desired to be 99.5%, the concentration of oxygen in the high-purity oxygen should not be lower than 99.5%.

[0059] Consider the total air intake of the first purge and the second purge. Since the purpose of the purge method 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 exhaust all 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%, a small amount of other gases is still allowed in the adsorption tower, and the concentration of other gases in the desorbed gas is not greater than 0.5%.

[0060] Furthermore, in the second purge step, high-purity gas is introduced into the adsorption tower through one end. This will cause the impurity gas in the adsorption tower to be accumulated in the space away from the high-purity gas inlet end along the purge direction. Therefore, as long as the oxygen concentration in the mixed gas in the space away from the high-purity gas inlet end of the adsorption tower is measured, the oxygen concentration of the mixed gas obtained by desorption can be calculated.

[0061] For example, according to Figure 1 and Figure 2 In the oxygen purification main unit 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 at the end of the adsorption tower far from the high-purity gas 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.

[0062] Further consider the relationship between the first preset value and the second preset value. Figure 2As shown, at the bottom end 101 of the adsorption tower, after the second purge step, only high-purity gas 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 gas. 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 gas 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 can be ignored compared with the oxygen adsorbed by the molecular sieve. Therefore, the oxygen concentration of this part can be considered as the concentration after 100% oxygen and high-purity gas are mixed, which will be greater than the oxygen concentration of high-purity gas. 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 gas 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.

[0063] In one case, the first preset value is greater than the second preset value, and the gas concentration of oxygen in the molecular sieve bed and the high-purity gas inlet 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, which is common in the state when the oxygen purification host is just turned on.

[0064] In another case, the first preset value is less than the second preset value and a certain difference is allowed. In this embodiment, this difference is called the first difference. That is, when the oxygen concentration at the end of the adsorption tower away from the high-purity gas inlet has reached a difference with the oxygen concentration of the desorbed gas that is less than or equal to the first difference, the second purge step is completed. In this case, a mixed gas with an oxygen concentration of the second preset value can be continuously and stably produced.

[0065] Further consider the range of the first difference. On the one hand, the first difference is not a fixed value. Take the oxygen purification host used to produce high-purity oxygen in this embodiment as an example. Under normal circumstances, the oxygen purification host used for medical use uses 93% to 95% general oxygen as the inlet, and the required product gas is 99.5% oxygen. In this case, the purge of high-purity oxygen makes the gas concentration of oxygen in the space at the outlet of the adsorption tower above 97 to 99% (according to the different structures of the adsorption tower, the different molecular sieve filling amounts, and the different concentrations of general oxygen, there may be fluctuations), that is, the oxygen concentration in the mixed gas obtained by desorption can reach 99.5%, and the first difference is usually not more than 3%. In other cases, when the general oxygen with a concentration of 93 to 95% is used as the inlet and the required product gas concentration is 99% oxygen (such as industrial oxygen), only high-purity oxygen purge is required to make the gas concentration of oxygen at the outlet of the adsorption tower above 95%, that is, the oxygen concentration in the mixed gas obtained by desorption can reach 99%, and the first difference is 4%.

[0066] On the other hand, when the adsorption tower structure, molecular sieve filling amount and molecular sieve bed position remain unchanged, the higher the expected concentration of oxygen in the desorbed gas, the smaller the first difference should be. This is because the concentration of oxygen in the desorbed gas is jointly affected by the oxygen concentrations of the three parts of the adsorption tower, and the oxygen concentrations at the high-purity gas inlet end and the molecular sieve bed are greater than or equal to the oxygen concentration of the high-purity gas. Therefore, the closer the oxygen concentration at the end of the adsorption tower away from the high-purity gas inlet is to the oxygen concentration requirement of the desorbed gas, the higher the oxygen concentration in the mixed gas obtained by desorption can be.

[0067] After determining the total air intake of the purging method according to the above method, further consider the air intake of the first purging step and the second purging step respectively. Compared with the second purging step, the first purging step may also cause impurity gas to enter the molecular sieve, which will reduce the concentration of the desorbed gas. Therefore, in this embodiment, the air intake of the mixed gas in the first purging step is limited to not more than the air intake of the high-purity gas in the second purging 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.

[0068] The source of the high purity gas in the second purge step can be as follows: Figure 1 In the embodiment shown, the mixed gas obtained by desorption from the adsorption tower is stored in a high-purity oxygen storage tank 2, and the high-purity oxygen storage tank 2 is connected to the bottom of the adsorption tower. According to the method of this embodiment, the mixed gas obtained by desorption can be used as the high-purity gas in the second purge step, and the second purge is performed by the air intake at the bottom of the adsorption tower to achieve recycling.

[0069] As another optional implementation, Figure 3As shown, the mixed gas obtained by desorption from another adsorption tower that is producing gas can also be used as the high-purity gas 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 to allow the high-purity oxygen produced by desorption from the adsorption tower 1B to flow into the bottom end of the adsorption tower 1A, thereby achieving the second purge step.

[0070] As another optional implementation, the second purge may be performed by using external high-purity gas. The external high-purity gas only needs to satisfy that the target gas concentration is greater than the second preset value, which will not be described in detail in this embodiment.

[0071] In this embodiment, the following method is provided to specifically implement the above-mentioned purging method.

[0072] As an optional specific way to implement the purging method, first, in the design stage of the entire pressure swing adsorption system, the time required for each step is estimated, and after assembly, factory testing is performed to fine-tune the time required for each step, and the results are fixed in the control software of the oxygen purification host.

[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 gas is the first end or the second end, and considering the source of the high-purity gas and the concentration of the target gas, the size of the first preset value can be preliminarily estimated. Further, the air intake rate of the mixed gas and the high-purity gas is designed as needed. For example, the air intake rate of the high-purity gas and the mixed gas can be designed to be a unified fixed value. Finally, determine the time ratio of the first purge time and the second purge time, for example, m:n.

[0074] After the entire pressure swing adsorption product is assembled, the target gas concentration in the space away from the high-purity gas inlet end of the adsorption tower and the target gas concentration of the desorbed gas can be actually measured, and the time of the first purge step and the second purge step can be adjusted synchronously according to the above-mentioned ratio of m:n. For the detection of the target gas concentration in the mixed gas in the space away from the high-purity gas inlet end of the adsorption tower, 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 gas inlet end. After the pressure swing adsorption equipment 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 relationship also needs to be adjusted to ensure that the intake amount of the mixed gas does not exceed the intake amount of the high-purity gas.

[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 pressure swing adsorption oxygen generator. The control system of the pressure swing adsorption oxygen generator will adjust the opening degree and / or on-off time of the corresponding valve in real time according to the detected gas concentration.

[0077] Considering that the concentration of the target gas in the desorbed mixed gas is constantly changing when the oxygen purification host is just started, the description of the target gas concentration in the mixed gas in the space located in the adsorption tower away from the high-purity gas inlet end in the purging method of 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 the target gas in the mixed gas obtained by desorption of the pressure swing adsorption system is stable within a certain range and no longer changes dramatically, that is, the state where the concentration of the desorbed gas changes dramatically when the machine is just started is excluded.

[0078] Embodiment 2:

[0079] The purging method provided in this embodiment is applied to Figure 4-5 The oxygen purification host part of the pressure swing adsorption oxygen concentrator is shown. 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, namely the general oxygen generator part, and a second-stage pressure swing adsorption system, namely the oxygen purification host part.

[0080] In this embodiment, the valve at the top of the adsorption tower is opened during the first purge and the second purge to discharge the gas from the adsorption tower. These gases still have a high oxygen content and can be used. Usually, these gases can be used as regeneration gas for the previous stage general oxygen generator, or they can be recycled as mixed gas for the oxygen purification host. Considering that the order of the first purge and the second purge steps is different, the concentration of the gas blown out is different. Therefore, in this embodiment, these gases can be reused in the following way.

[0081] As an optional implementation, the Figure 4 The first oxygen reflux tank 601 shown is recollected 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 setting can effectively reduce the oxygen consumption and improve the oxygen recovery rate of the entire pressure swing adsorption oxygen generator.

[0082] As another optional implementation, the Figure 5The second oxygen buffer tank 602 shown temporarily stores this part of the mixed gas and enters the oxygen purification host part again as a mixed gas. This setting can effectively reduce the consumption of oxygen, and the oxygen purification host 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 host as regeneration gas, and can realize the modular production of the oxygen purification host and the general oxygen generator. That is, the oxygen purification host of this embodiment can be applied to the back end of various other general oxygen generators, which is convenient for the production and assembly of the entire pressure swing adsorption oxygen generator.

[0083] In the above method, the same pipeline is used 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, and set up multiple oxygen buffer tanks and / or oxygen recovery tanks for use in different occasions.

[0084] For example, you can follow Figure 6 , Figure 7 mode settings. Figure 6 is Figure 4 On the basis of the arrangement shown, a second oxygen reflux tank 701 is added to collect the gas blown out in the first purge step and enter the first-stage pressure swing adsorption system as the purge regeneration gas of the first-stage pressure swing adsorption system. Figure 7 is Figure 5 On the basis of the arrangement shown, a third oxygen buffer tank 702 is added to collect the gas blown out in the first purge step and use it as a mixed gas to enter the oxygen purification main unit again.

[0085] The purging method of the oxygen purification host 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 the oxygen-nitrogen separation pressure swing adsorption oxygen generator of the common knowledge technology.

[0086] Embodiment 3:

[0087] As a third embodiment of the present invention, a pressure swing adsorption method is provided. The pressure swing adsorption method provided in this embodiment can be applied to Figure 1 as well as Figure 3-Figure 7 The oxygen purification host part shown in the figure includes the pressurization step, exhaust step and desorption step in the conventional pressure swing adsorption method, and the purge method in Example 1 or 2. The purge method in Example 1 or 2 is applied after the pressurization step and the exhaust step and before the desorption step. The specific methods of the pressurization step, the exhaust step and the desorption step can be referred to the description in Example 1, and can also be carried out in other ways known in the art.

[0088] Embodiment 4:

[0089] The pressure swing adsorption method provided in this embodiment is based on Embodiment 3, and a pressure equalization step is added. The pressure equalization step is after the second purge step and before the desorption step.

[0090] As a preferred method, the pressure equalization method in this embodiment is shown in Figure 8 , connect the second end of the adsorption tower to the first end of another adsorption tower for cross-pressure equalization. By 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 valve control, 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.

[0091] Embodiment 5:

[0092] As the fifth embodiment of the present invention, a purging method for a pressure swing adsorption oxygen purification host in an oxygen recovery device for kiln tail gas is provided. One of the production steps of ternary lithium batteries is to sinter in a kiln in a high-purity oxygen environment. The tail gas generated in this process will contain a large amount of oxygen, and recycling this part of the tail gas can effectively reduce the consumption of oxygen.

[0093] Different from Example 3 or 4, in this embodiment, since the kiln requires a high-purity oxygen environment for sintering, the oxygen source that supplies oxygen to the kiln can be used as the high-purity gas in the second purge step, or the high-purity oxygen desorbed after pressure swing adsorption and the oxygen source can be used together as the gas for the second purge step. For the other steps in this embodiment, pressure swing adsorption oxygen purification can be carried out in the manner of any of Examples 3 or 4. In the scenario of kiln tail gas recovery, there is usually no previous stage pressure swing adsorption device. Therefore, the method of setting an oxygen buffer tank in Example 2 can be referred to, and the mixed gas purged in the first purge step and / or the second purge step can be recovered and used as the mixed gas for the pressure swing adsorption oxygen purification main unit.

[0094] In addition to the above embodiments, the purging method described in the present invention can also be applied to other pressure swing adsorption or temperature swing adsorption fields. For example, in a methane purification device for a methane / nitrogen mixture, a method similar to that in the above embodiment 1 can also be used. The methane purification device also needs to make the following changes compared to the oxygen purification device in embodiment 1. First, the adsorbent used for the methane / nitrogen mixture needs to have a good adsorption effect on methane and a poor adsorption effect on nitrogen, and the adsorbent in the oxygen purification device cannot be directly used. Secondly, methane gas is a harmful gas. Therefore, the mixed gas blown out of the methane / nitrogen mixture and the mixed gas blown out of high-purity methane are usually recovered through a methane buffer tank and used again as a mixed gas. For another example, for a carbon dioxide recovery device in industrial waste gas, a device similar to the above embodiment can also be used, which will not be repeated here.

[0095] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of the above method when executed by a processor. The computer-readable storage medium may include, but is not limited to, any type of disk, including a floppy disk, an optical disk, a DVD, a CD-ROM, a micro drive, and a magneto-optical disk, a ROM, a RAM, an EPROM, an EEPROM, a DRAM, a VRAM, a flash memory device, a magnetic card or an optical card, a nanosystem (including a molecular memory IC), or any type of medium or device suitable for storing instructions and / or data.

[0096] In order to better describe the present invention, some terms and some implementation methods of the present invention are explained as follows.

[0097] In the present invention, the mixed gas refers to the gas that enters the pressure swing / temperature swing adsorption device as a raw material. For example, in the oxygen purification host of Example 1, the mixed gas is the general oxygen produced by the previous general oxygen generator, which includes 93% to 95% oxygen concentration, and the remaining components are mainly nitrogen and argon. In other embodiments, the mixed gas can also be other gases, such as air.

[0098] The pressure swing / temperature 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 / temperature 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 / temperature swing adsorption, in the present invention, the gases after pressure swing / temperature swing adsorption are respectively called exhaust gas and desorbed gas.

[0099] 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.

[0100] In the present invention, the target gas is a gaseous substance in a chemical sense, for example, the target gas may be oxygen.

[0101] 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.

[0102] 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 / temperature swing adsorption method, and a low flow rate scheme or a high flow rate scheme can be adopted as needed.

[0103] 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 / temperature swing adsorption.

[0104] 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.

[0105] In the above embodiment, the adsorption tower is divided into three spatial 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 spatial 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 / temperature 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.

[0106] 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 gas, 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.

[0107] 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.

[0108] In the present invention, the pressure swing adsorption method refers to a method in which a molecular sieve adsorbs a certain gas under a high pressure and desorbs the gas under a low pressure. The temperature swing adsorption method refers to a method in which a molecular sieve adsorbs a certain gas at different temperatures and desorbs the gas at another temperature. The pressure swing / temperature swing adsorption in the present invention includes but is not limited to various adsorption methods such as atmospheric pressure swing adsorption, vacuum pressure swing adsorption, and mixed pressure swing / temperature swing adsorption.

[0109] The pressure swing / temperature swing adsorption method described in the present invention is a pressure swing / temperature swing adsorption method for one of the adsorption towers. In a conventional double-tower pressure swing / temperature 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.

[0110] The pressure swing / temperature 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, a person skilled in the art can select a common zeolite molecular sieve as the molecular sieve of the general oxygen generator, and select a carbon molecular sieve as the molecular sieve of the oxygen purification host. For another example, a person skilled in the art can also select a silver-loaded zeolite molecular sieve as the molecular sieve of the oxygen purification host. The specific model selection of the molecular sieve, such as the pore size of the molecular sieve, etc., are all routine choices that a person skilled in the art can make according to the needs of implementing the steps of the above-mentioned embodiments.

[0111] 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 target gas. Those skilled in the art may also choose other purge regeneration methods known in the art to perform purge regeneration of molecular sieves. 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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 purging method, which is applied to a pressure swing / temperature swing adsorption method, wherein the pressure swing / temperature swing adsorption method acts on a mixed gas to adsorb a target gas therein and then desorb the target gas to separate the target gas from the mixed gas; characterized in that: The purge method is applied after the exhaust step and before the desorption step; The purging method comprises a first purging step and a second purging step performed in a sequential order; The first purging step is to purge the adsorption tower with the mixed gas; the second purging step is to purge the adsorption tower with high purity gas entering from one end of the adsorption tower; The total air intake volume of the first purge step is less than the total air intake volume of the second purge step; The total time of the first purging step and the second purging step is long enough so that when the pressure swing / temperature swing adsorption gas production reaches stability, the target gas concentration of the mixed gas in the space located at the end of the adsorption tower away from the high purity gas inlet is not less than the first preset value; Among them, the high-purity gas is a mixed gas containing a target gas, and the concentration of the target gas in the high-purity gas is not less than a second preset value, and the second preset value is the concentration of the target gas in the gas desorbed by the pressure / temperature swing adsorption method; the first preset value is less than the second preset value.

2. The purging method according to claim 1, characterized in that: There is a first difference between the first preset value and the second preset value.

3. The purging method according to claim 2, characterized in that: The first difference decreases as the second preset value increases.

4. The purging method according to claim 1, characterized in that: The high-purity gas is the gas obtained by desorption using the pressure swing / temperature swing adsorption method, or is a mixed gas containing a high-purity target gas from an external source.

5. The purging method according to claim 1, characterized in that: The gas purged out in the first purging step and / or the gas purged out in the second purging step is recovered and then fed into the adsorption tower as a mixed gas.

6. The purging method according to claim 1, characterized in that: The gas purged out in the first purging step and / or the gas purged out in the second purging step are recovered and used for the production of the mixed gas.

7. A pressure swing / temperature swing adsorption method for separating a target gas from a mixed gas, wherein the pressure swing / temperature swing adsorption method adsorbs the target gas and then obtains a mixed gas rich in the target gas by desorption, wherein: The pressure swing / temperature swing adsorption method at least comprises, on an adsorption tower, after the exhaust step, carrying out the purge method according to any one of claims 1 to 6, and then carrying out the desorption step.

8. The pressure swing / temperature swing adsorption method according to claim 7, characterized in that: The method further comprises a pressure equalization step, wherein the pressure equalization step is performed by cross pressure equalization before the desorption step.

9. A pressure swing / temperature swing adsorption device, characterized in that: The method comprises at least one processing unit and at least one storage unit, wherein the storage unit stores a computer program, and when the computer program is executed by the processing unit, the processing unit drives the pressure swing / temperature swing adsorption device to execute the steps of the method according to any one of claims 1 to 6, or drives the pressure swing / temperature swing adsorption device to execute the steps of the method according to any one of claims 7 to 8.

10. A computer-readable storage medium, characterized in that: It stores a computer program, and when the computer program is executed by a processor, it drives the pressure swing / temperature swing adsorption device to execute the steps of the method described in any one of claims 1 to 6, or drives the pressure swing / temperature swing adsorption device to execute the steps of the method described in any one of claims 7 to 8.

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