Gas storage system and gas extraction method

Abstract

The present invention relates to a gas storage system and a gas extraction method, which includes: a storage tank group, a compressor group of a preset number of levels, and a control device connected to the compressor group; each storage tank in the storage tank group is individually connected to the inlet main line of each level of the compressor group; the control device is used to control the compressor group to extract gas from the storage tank group in a stepped gas extraction method. Each storage tank can be individually connected to the compressor group of each level, which is suitable for the traditional gas extraction method and the stepped gas extraction method, and the gas extraction method is more flexible. In addition, the pressure of each storage tank can be changed independently without being affected by other storage tanks, which can ensure that there are multiple levels of gas pressure in the system, thereby improving the regulation ability of the system. The present invention can obtain a smaller total compressor capacity while meeting the same gas supply demand, which can effectively promote energy conservation and emission reduction of the system, reduce initial investment, and create better economic benefits.

Description

Technical Field

[0001] The invention relates to a gas storage system and a gas extraction method. Background Art

[0002] Gas storage systems can enhance the stability of volatile systems. Their gas supply and regulation capabilities directly impact the safe and stable operation of the system they operate in. Furthermore, for volatile systems, such as green hydrogen, the investment cost of hydrogen storage systems represents a significant portion of the overall green hydrogen system. Technologies to reduce this investment are currently a key focus for researchers.

[0003] During the operation of a traditional gas storage system, the first-stage compressor unit is first activated to simultaneously extract gas from all storage tanks until no more gas can be extracted. At the same time, the second-stage compressor unit is activated, and so on, until all compressor units are running simultaneously and no gas can be extracted. Summary of the Invention

[0004] The present invention was developed to construct a new gas storage system structure, develop a tiered gas extraction method, and a new gas storage system structure capacity configuration method, thereby ensuring the gas supply capacity of the gas storage system while reducing investment costs and improving adjustment flexibility. The present invention provides a gas storage system and gas extraction method, and the technical solutions proposed by the present invention are as follows:

[0005] As one aspect of the present invention, it relates to a gas storage system, comprising: a storage tank group, a compressor group of a preset order, and a control device connected to the compressor group;

[0006] Each storage tank in the storage tank group is individually connected to the inlet main line of each stage of the compressor unit;

[0007] The control device is used to control the compressor unit to take gas from the storage tank group in a step-by-step gas taking manner.

[0008] As another aspect of the present invention, it relates to a gas extraction method, which is implemented using the gas storage system as described in the first aspect.

[0009] In some embodiments, the gas extraction method includes:

[0010] Using a single-stage compressor unit to draw gas from the first tank in the tank group until the ratio of the gas supply pressure P to the inlet pressure is equal to the pressure ratio z1 of the compressor unit. After the first gas drawing operation is completed, the pressure of the first tank is P1.

[0011] After the first gas extraction operation is completed, an additional compressor unit is activated to continue extracting gas from the first storage tank, compressing the gas to P1, and then entering the single-stage compressor unit to continue compressing it to the supply pressure P. The single-stage compressor unit is then used to extract gas from the second storage tank until the pressure in the second storage tank reaches P1. After the second gas extraction operation is completed, the pressure in the first storage tank is P2.

[0012] Each time a gas extraction operation is performed, one more compressor unit is activated to extract gas until the preset number of compressor units are activated and the number of remaining storage tanks is not less than the preset number, and all compressor units are used to extract gas from the preset number of storage tanks at the same time;

[0013] The gas extraction operation is carried out until the number of remaining storage tanks from which gas can be extracted is less than the preset number, and all the compressor units are used to extract gas from the remaining storage tanks from which gas can be extracted simultaneously, until the gas in all the storage tanks can no longer be extracted, and the gas extraction is terminated.

[0014] In some embodiments, each time a compressor unit is activated to extract air, the original last compressor unit is the second compressor unit, the latest compressor unit activated is the first compressor unit, and the earliest activated compressor unit is the last compressor unit.

[0015] In some embodiments, during a gas extraction operation in which the compressor groups of the preset order are simultaneously activated and the number of remaining storage tanks is not less than the preset order, and during a gas extraction operation before this, the inlet gas volume flow rate of a single storage tank directly entering the mth-stage compressor group without passing through other-stage compressor groups is determined by solving the following set of equations:

[0016]

[0017] Where, It represents the inlet gas volume flow rate of a single tank directly entering the mth level compressor unit without passing through other level compressor units, W represents the gas supply demand, P0 represents the maximum gas storage pressure of a single tank, ρ0 represents the density of the gas at pressure P0, P m It represents the inlet pressure of the mth-stage compressor unit after the mth-step gas extraction operation is completed. It is also the pressure after the gas enters the storage tank of the mth-stage compressor unit directly without passing through other levels of compressor units during the mth-step gas extraction operation. ρ m Indicates pressure as P m The density of the gas at R It represents the volume of a single storage tank, and M represents the number of compressor stages.

[0018] In some embodiments, during a gas extraction operation in which the preset number of compressor units is simultaneously activated and the number of remaining storage tanks is not less than the preset number, and in a gas extraction operation before this, the inlet gas volume flow rate of the compressor unit is determined by the following formula:

[0019]

[0020] Where, represents the total volume flow rate of the inlet gas of the mth stage compressor unit, that is, the capacity configuration of the mth stage compressor unit, It represents the inlet gas volume flow rate of a single tank directly entering the mth-level compressor unit without passing through other levels of compressor units, ρ m Indicates pressure as P m The density of the gas at m It represents the inlet pressure of the mth stage compressor unit after the mth step of gas extraction operation, and M represents the number of compressor stages.

[0021] In some embodiments, in a gas extraction operation in which the preset order of compressor groups are simultaneously activated and the number of remaining storage tanks is not less than the preset order of gas extraction, and in a gas extraction operation before this, the number of compressors in the compressor group is determined by the following formula:

[0022]

[0023] Where n m Indicates the number of compressors in the m-th compressor group, It represents the inlet gas volume flow rate of a single tank directly entering the mth level compressor unit without passing through other level compressor units. represents the rated intake volume flow rate of a single compressor in the m-th compressor group, ρ m Indicates pressure as P m The density of the gas at m It represents the inlet pressure of the mth stage compressor unit after the mth step of gas extraction operation, and M represents the number of compressor stages.

[0024] In some embodiments, in a gas extraction operation in which the preset order of compressor units are simultaneously activated and the number of remaining storage tanks is not less than the preset order of compressor units, and in a gas extraction operation before this, the gas extraction amount of the storage tank is determined by the following formula:

[0025] w m,m =(ρ m-1 -ρ m )V R m∈M,m=1,2,…M;

[0026] Among them, w m,m represents the gas volume of the mth tank in the mth gas extraction operation, ρ m Indicates pressure as Pm The density of the gas at m-1 Indicates pressure as P m-1 The density of the gas at m It represents the inlet pressure of the mth stage compressor unit after the mth step of gas extraction operation, P m-1 It represents the inlet pressure of the m-1th stage compressor unit after the m-1th step of gas extraction operation, and M represents the number of compressor stages.

[0027] In some embodiments, in a gas extraction operation in which the preset order of compressor units are simultaneously activated and the number of remaining storage tanks is not less than the preset order of units, and in a gas extraction operation before this, the gas supply time of the mth gas extraction operation is determined by the following formula:

[0028]

[0029] Among them, t m Indicates the gas supply time of the mth step gas operation, ρ m Indicates pressure as P m The density of the gas at m-1 Indicates pressure as P m-1 The density of the gas at m It represents the inlet pressure of the mth stage compressor unit after the mth step of gas extraction operation, P m-1 It represents the inlet pressure of the m-1th stage compressor unit after the m-1th step gas extraction operation, M represents the number of compressor stages, and W represents the gas supply demand.

[0030] In some embodiments, when the gas extraction operation is carried out until the number n of remaining storage tanks from which gas can be extracted is less than M, and M-level compressor groups are activated to extract gas from the remaining storage tanks from which gas can be extracted, the total air intake flow rates of the nth to mth stage compressor groups are the same.

[0031] Based on the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0032] The gas storage system provided by this invention allows each tank to be independently connected to a compressor unit at each level, making it suitable for both traditional and cascaded gas extraction methods, providing greater flexibility. Furthermore, the pressure of each tank can be independently varied without being affected by other tanks, ensuring the presence of gas at multiple pressure levels in the system and improving the system's regulation capabilities.

[0033] The gas extraction method provided by the present invention uses a cascade gas extraction method, which can complete the operation of extracting gas from different pressure storage tanks at the same time, realize the comprehensive utilization of system energy, and reduce the capacity demand of the compressor compared with the traditional gas extraction method. Moreover, by adopting a cascade gas extraction scheme and optimizing the design of the capacity configuration of the compressor unit of the gas storage system, under the cascade gas extraction method, as long as the number of remaining storage tanks that can be extracted is greater than 1, when the m-level compressor units are started at the same time, the second to the m-th level compressor units have two gas extraction sources, namely the outlet gas of the previous level compressor unit and the gas in a certain storage tank. The total amount of gas extracted by the compressor unit gradually increases with the increase of the number of stages. The capacity configuration of the m-th level compressor unit of the gas storage system is When the gas supply demand is constant, the gas output at the outlet of the mth-stage compressor unit equals the gas supply demand. Compared to the traditional gas extraction method, where the gas output at the outlet of each compressor unit is equal to the gas supply demand, the cascaded gas extraction method reduces the gas extraction of compressor units beyond the mth stage, requiring a smaller total compressor capacity. This invention can achieve a smaller total compressor capacity while meeting the same gas supply demand, effectively promoting system energy conservation and emission reduction, reducing initial investment, and creating better economic benefits.

[0034] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or understood by practicing the present invention. The purposes and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 It is a schematic diagram of the structure of a traditional gas storage system;

[0038] Figure 2 This is a schematic diagram of the structure of the gas storage system that can realize cascade gas extraction provided by the present invention;

[0039] Figure 3 This is a schematic diagram of the operation mode of the gas storage system in a certain step of traditional gas extraction;

[0040] Figure 4This is a schematic diagram of the operation mode of the gas storage system in a certain step of the cascade gas extraction provided by the present invention;

[0041] Figure 5 This is a structural diagram of a primary gas storage system provided by an embodiment of the present invention;

[0042] Figure 6 It is a structural diagram of a two-stage gas storage system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0043] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0044] Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. In the following description, when referring to the drawings, like numbers in different figures represent like or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present invention, as detailed in the appended claims.

[0045] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0046] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0047] The inventor found in his work that the structure of the traditional gas storage system is similar to Figure 1As shown, during the operation of a traditional gas storage system, the first-stage compressor unit is first activated to extract gas, and when no more gas can be extracted, the second-stage compressor unit is activated at the same time, and so on, until all the compressor units are running at the same time and no gas can be extracted. When extracting gas in this way, the pressure change in the gas storage system is single, which affects the flexibility of system regulation. In addition, when there are many storage tanks, if the pressure level of the configured compressor is not enough, a large amount of gas cannot be extracted from the storage tank, resulting in a waste of resources; if a compressor with sufficient capacity is configured, the system investment cost will be greatly increased, which cannot meet the inventor's expectations. There is room for improvement in the structure of the traditional gas storage system, the gas extraction method, and the system capacity configuration design method. After further research and development, the inventor made the present invention.

[0048] To address the low gas extraction efficiency, poor adjustment flexibility, and high investment costs of current traditional gas storage systems, the present invention proposes a new and efficient gas storage system structure, and simultaneously develops a tiered gas extraction method and a system capacity configuration design method. This invention belongs to the field of energy and chemical technology, specifically to a gas storage system operation optimization technology. It invents a new gas storage system structure and design method that adopts a tiered gas extraction method to enrich the gas pressure levels of the gas storage system and increase the flexibility of the gas extraction scheme. While meeting gas supply demand, it reduces the capacity configuration and operating energy consumption of the compressor unit, thereby improving the economic efficiency of the gas storage system.

[0049] Example 1

[0050] The embodiment of the present invention provides a gas storage system, referring to Figure 2 As shown, it includes: a storage tank group, a compressor group of preset order and a control device connected to the compressor group;

[0051] Each storage tank in the storage tank group is individually connected to the inlet main line of each stage of the compressor unit;

[0052] The control device is used to control the compressor unit to take gas from the storage tank group in a step-by-step gas taking manner.

[0053] In the gas storage system provided by the present invention, each tank can be independently connected to a compressor unit at each level, making it suitable for both traditional and cascaded gas extraction methods, providing greater flexibility. Furthermore, the pressure of each tank can be independently varied without being affected by other tanks, ensuring the system has multiple pressure levels, improving the system's regulation capabilities.

[0054] The present invention also includes a pipeline system, and the storage tank group, the compressor group and the compressor group are connected by pipelines.

[0055] In order to compare the gas storage system provided in the embodiment of the present invention with a traditional gas storage system, the process of extracting gas using the traditional gas storage system is first described.

[0056] In the embodiment of the present invention, it is assumed that:

[0057] 1) The gas storage pressure of each tank in the tank group is the same;

[0058] 2) The gas supply demand of the gas-supplied equipment is stable;

[0059] The following parameters are known:

[0060] 1) The number of tanks in the tank group N, the number of tanks N = |N|, and the rated gas storage capacity of a single tank M R (kg), volume V R (m 3 ) and the maximum gas storage pressure P0 (MPa), the gas storage temperature is T;

[0061] 2) The set of compressor group levels M, the number of compressor stages M = |M|, and the pressure ratio of the m-th compressor group is z m , the rated intake volume flow rate of a single compressor in the mth stage compressor unit

[0062] 3) Temperature is T, pressure is P m and P R The gas densities are ρ m and ρ0(kg·m -3 ), the density of the gas under standard conditions ρ s (kg·m -3 ); where P m (MPa) is the inlet pressure of the gas when it passes through the mth stage compressor unit, which is calculated by the following formula:

[0063]

[0064] 4) Gas supply demand of downstream devices that require gas from the gas storage system W (kg·h -1 ) and gas supply pressure P (MPa);

[0065] It should be noted that the inlet pressure mentioned in the embodiment of the present invention refers to the gas pressure entering each stage of the compressor unit. The capacity of the compressor unit adopts the inlet gas volume flow rate. The gas supply pressure refers to the gas pressure that downstream devices require from the gas storage system. This refers to the final outlet pressure of the compressor unit after the gas in the storage tank passes through n-stage compressor units, i.e., the outlet pressure of the last compressor unit. The gas pressure starts low, then rises to a certain level after passing through the first-stage compressor unit before passing through the second-stage compressor unit. The outlet pressure of the first-stage compressor unit is the inlet pressure of the second-stage compressor unit, and so on. The gas supply pressure is the outlet pressure of the last compressor unit.

[0066] It should also be noted that, during the gas extraction process, each time a compressor unit is added, the embodiment of the present invention refers to the added compressor unit as the first-stage compressor unit, and the previous compressor unit as the second-stage compressor unit. Specifically, in the second gas extraction operation, the newly enabled compressor unit is the first-stage compressor unit, and the single-stage compressor unit is the second-stage compressor unit, and so on. When the preset order of compressor units are enabled at the same time and the number of remaining storage tanks is not less than the preset order of units, as well as in the gas extraction step before this, that is, in the m-th gas extraction operation, the most recently enabled compressor unit is the first-stage compressor unit, and the earliest enabled compressor unit is the m-th-stage compressor unit.

[0067] A specific embodiment has been described, referring to Figure 5 The figure shows a single-stage compressor group when only one compressor group is enabled, which can also become the first-stage compressor group. Figure 6 As shown, after one level of compressor unit is added and activated, the original single-stage compressor unit is called the second-stage compressor unit, and the newly activated compressor unit is called the first-stage compressor unit.

[0068] The structure of the traditional gas storage system refers to Figure 1 As shown, the storage tanks in the tank group are connected in parallel, and their pressures change synchronously. After the outlet pipelines of each storage tank are connected and merged, they can enter the compressor groups of each level respectively. The compressor groups of the same level are connected in parallel, and the compressor groups of different levels are connected in series. Figure 3 As shown, the traditional gas extraction method includes the following steps:

[0069] S101. Use a single-stage compressor unit to synchronously extract gas from all tanks in the tank group. When the ratio of the supply pressure P to the inlet pressure is equal to the pressure ratio z1 of the compressor unit, the first step of gas extraction is completed. At this time, the pressure of all tanks is P1, and the amount of gas extracted is (ρ0-ρ1)V R In order to meet the gas supply demand, the inlet gas volume flow rate of the single-stage compressor unit and the number of compressors in the single-stage compressor unit are W / ρ1 and N respectively. The required capacity of compressor units of other grades is 0.

[0070] S102. Add and activate a first-stage compressor unit (this is the first-stage compressor unit), compress the gas to P1, and then enter the previous single-stage compressor unit (this is the second-stage compressor unit) to continue compressing to the supply pressure P. When the ratio of the outlet pressure P1 of the first-stage compressor unit to the inlet pressure P2 is equal to the pressure ratio z2 of the compressor unit, the second step of gas extraction is completed. At this time, the pressure of all storage tanks is P2, and the amount of gas extracted is (ρ1-ρ2)V R N, the inlet gas volume flow rates of the first and second stage compressor groups required to meet the gas supply demand are W / ρ1 and W / ρ2 respectively, and the number of compressors in the first and second stage compressor groups is and

[0071] S103, and so on, until the M-level compressor groups are activated at the same time, and the gas in the tank group cannot be taken out, the gas extraction operation ends. At this time, in order to meet the gas supply demand, the required inlet gas volume flow rate of each level compressor group is W / ρ m , the number of compressors in the mth stage compressor group is The gas supply capacity is (ρ0-ρ m )V R N.

[0072] The gas extraction method provided by the embodiment of the present invention is described. The present invention is a gas storage system and configuration method that can adopt the step-by-step gas extraction technology. The structure of the gas storage system adopted is shown in the attached figure. Figure 2 As shown, unlike the traditional gas storage system structure, the tanks in the tank group are independent of each other, their pressures can be different, and each tank can be individually connected to the inlet main line of each stage of the compressor group.

[0073] Reference Figure 4 As shown in FIG, the cascade gas extraction technology mainly includes the following steps:

[0074] S201, using a single-stage compressor unit to draw gas from the first storage tank in the storage tank group until the ratio of the gas supply pressure P to the inlet pressure equals the pressure ratio z1 of the compressor unit. After the first gas drawing operation is completed, the pressure of the first storage tank is P1;

[0075] S202: After the first gas extraction operation is completed, a first-stage compressor unit is activated to continue extracting gas from the first storage tank. After compressing the gas to P1, the gas enters the single-stage compressor unit and continues to be compressed to the supply pressure P. The single-stage compressor unit is then used to extract gas from the second storage tank until the pressure in the second storage tank reaches P1. After the second gas extraction operation is completed, the pressure in the first storage tank is P2.

[0076] S203. Each time a gas extraction operation is performed, one more compressor unit is activated to extract gas until the preset number of compressor units are activated and the number of remaining storage tanks is not less than the preset number, and all compressor units are used to extract gas from the preset number of storage tanks at the same time; extracting gas from the preset number of storage tanks mentioned here refers to extracting gas from the first preset number of storage tanks in the gas tank group.

[0077] Taking the use of M-level compressor units for gas extraction as an example, until M-level compressor units are simultaneously activated and the number of remaining storage tanks is not less than M, gas will be extracted from M storage tanks simultaneously. In order to meet the gas supply demand, during the process of using all compressor units to extract gas from the preset number of storage tanks at the same time, the inlet gas volume flow rate of a single storage tank directly entering the m-th level compressor unit without passing through other levels of compressor units is determined by solving the following equations:

[0078]

[0079] Where, It represents the inlet gas volume flow rate of a single tank directly entering the mth level compressor unit without passing through other level compressor units, W represents the gas supply demand, P0 represents the maximum gas storage pressure of a single tank, ρ0 represents the density of the gas at pressure P0, P m It represents the inlet pressure of the mth-stage compressor unit after the mth-step gas extraction operation is completed. It is also the pressure after the gas enters the storage tank of the mth-stage compressor unit directly without passing through other levels of compressor units during the mth-step gas extraction operation. ρ m Indicates pressure as P m The density of the gas at R Indicates the volume of a single tank.

[0080] S204, the gas extraction operation is performed until the number of remaining storage tanks from which gas can be extracted is less than the preset number, and all the compressor units are used to extract gas from the remaining storage tanks from which gas can be extracted simultaneously, until the gas in all the storage tanks can no longer be extracted, and the gas extraction is terminated.

[0081] In the above step S204, when the gas extraction operation is performed until the number of remaining tanks that can be extracted is less than M, the M-level compressor groups are activated at the same time to extract gas from the remaining tanks that can be extracted, but the total intake flow rate of the n-th to m-th level compressor groups is the same, and the inlet gas volume flow rate of a single tank directly enters the first-level compressor group to the n-th level compressor group without passing through other level compressor groups The calculation method of is the same as when gas is taken from M storage tanks at the same time, that is, it is determined using the above formula 2. The gas taking operation continues until the gas in all storage tanks can no longer be taken out.

[0082] In the gas extraction operation in which the compressor groups of the preset order are activated simultaneously and the number of remaining storage tanks is not less than the preset number, and in the gas extraction operation before that (i.e., in the above steps S201-S203), the inlet gas volume flow rate of the m-th compressor group is determined by the following formula:

[0083]

[0084] Where, represents the total volume flow rate of the inlet gas of the mth stage compressor unit, that is, the capacity configuration of the mth stage compressor unit, It represents the inlet gas volume flow rate of a single tank directly entering the mth-level compressor unit without passing through other levels of compressor units, ρ m Indicates pressure as P m The density of the gas at m It represents the inlet pressure of the mth stage compressor unit after the mth step of gas extraction operation, and M represents the number of compressor stages.

[0085] In a gas extraction operation in which the preset number of compressor groups is simultaneously activated and the number of remaining storage tanks is not less than the preset number, and in a gas extraction operation before this, the number of compressors in the compressor group is determined by the following formula:

[0086]

[0087] Where n m Indicates the number of compressors in the m-th compressor group, It represents the inlet gas volume flow rate of a single tank directly entering the mth level compressor unit without passing through other level compressor units. represents the rated intake volume flow rate of a single compressor in the m-th compressor group, ρ m Indicates pressure as P m The density of the gas at m It represents the inlet pressure of the mth stage compressor unit after the mth step of gas extraction operation, and M represents the number of compressor stages.

[0088] In the gas extraction operation in which the compressor units of the preset order are activated simultaneously and the number of remaining storage tanks is not less than the preset number, as well as in the gas extraction operation before this, the gas extraction amount of the storage tank is determined by the following formula:

[0089] w m,m =(ρ m-1 -ρ m )V R m∈M,m=1,2,…M, Formula 5;

[0090] Where w m,m represents the gas volume of the mth tank in the mth gas extraction operation, ρ m Indicates pressure as Pm The density of the gas at m-1 Indicates pressure as P m-1 The density of the gas at m It represents the inlet pressure of the mth stage compressor unit after the mth step of gas extraction operation, P m-1 It represents the inlet pressure of the m-1th stage compressor unit after the m-1th step of gas extraction operation, and M represents the number of compressor stages.

[0091] In the gas extraction operation in which the compressor units of the preset order are activated simultaneously and the number of remaining storage tanks is not less than the preset number, as well as in the gas extraction operation before this, the gas supply time of each gas extraction operation is determined by the following formula:

[0092]

[0093] Among them, t m Indicates the gas supply time of the mth step gas operation, ρ m Indicates pressure as P m The density of the gas at m-1 Indicates pressure as P m-1 The density of the gas at m It represents the inlet pressure of the mth stage compressor unit after the mth step of gas extraction operation, P m-1 It represents the inlet pressure of the m-1th stage compressor unit after the m-1th step gas extraction operation, M represents the number of compressor stages, and W represents the gas supply demand.

[0094] It's important to note that the traditional and cascaded gas extraction steps don't need to be completed completely. As each gas extraction step is completed, the amount of gas removed decreases, but the cost increases. Therefore, when optimizing system configuration, the system's gas supply capacity, the number of compressor stages, and the number of compressors per stage should be determined based on system economic considerations.

[0095] Through the cascade gas extraction method provided by the present invention, it can be found that in the cascade gas extraction method, as long as the number of remaining storage tanks that can be extracted is greater than 1, when the m-stage compressor group is started at the same time, the second to the m-stage compressor groups have two gas extraction sources, namely the outlet gas of the previous stage compressor group and the gas in a certain storage tank. The total gas extraction amount of the compressor group gradually increases with the increase of the number of stages. The capacity configuration of the m-stage compressor group of the gas storage system is When the gas supply demand is constant, the gas volume at the outlet of the m-th compressor unit is equal to the gas supply demand. Compared with the traditional gas extraction method in which the gas volume at the outlet of each compressor unit is the gas supply demand, the use of a cascade gas extraction method reduces the gas extraction volume of compressor units other than the m-th level, and the total compressor capacity required is smaller. When the gas extraction operation reaches the step of simultaneously starting m-level compressor units to extract gas from m storage tanks, the schematic diagrams of the traditional gas extraction and cascade gas extraction system operation modes are shown in Appendix 2 and Appendix 3. In summary, the gas storage system solution obtained by using the cascade gas extraction method and equipment configuration design method described in the present invention is more economical than the traditional gas storage system in terms of both initial investment and operating costs.

[0096] Example 2

[0097] In order to more clearly illustrate the gas storage system and gas extraction method provided in the embodiment of the present invention and verify the accuracy of the method, the embodiment of the present invention extracts gas from hydrogen storage systems that apply the traditional gas storage system and the gas storage system structure of the present invention, and compares and analyzes the gas extraction results.

[0098] A gaseous hydrogen storage system, the storage tank unit includes N = 5 identical hydrogen storage tanks, the maximum gas storage pressure P R The pressure is 3.2 MPa, the hydrogen storage temperature is room temperature, and the storage tank volume is V R 1103.65m 3 , the gas storage capacity is 2839.68kg, the compression ratio of each level compressor unit is z m The rated intake volume flow rate of each compressor level is 2. Both are 15000m 3 ·h -1 , the system gas supply demand W is 8874kg·h -1 , the gas supply pressure P is 3.2MPa. The density of hydrogen at different temperatures and pressures is shown in Table 1.

[0099] Table 1 Summary of hydrogen density at different temperatures and pressures

[0100] Hydrogen temperature (℃) Hydrogen pressure (MPa) <![CDATA[Hydrogen density (kg·m -3 )]]> 25 0.4 0.3248 25 0.8 0.6488 25 1.6 1.294 25 3.2 2.573 0 0.1 0.08874

[0101] When using a traditional hydrogen storage structure and gas extraction method, assuming that the compressor unit includes M=3 levels, the gas extraction method is divided into three steps.

[0102] First, a single-stage compressor unit is used to synchronously extract gas from all tanks in the tank group. When the ratio of the supply pressure of 3.2 MPa to the inlet pressure is equal to the pressure ratio of the compressor unit of 2, the first step of gas extraction is completed. At this time, the pressure of all tanks is 1.6 MPa. The amount of gas extracted from each tank is:

[0103] (2.573-1.294)×1103.65=1412kg;

[0104] The first step of gas supply time is:

[0105]

[0106] To meet the gas supply demand, the required single-stage compressor unit inlet gas volume flow rate and the number of compressors in the single-stage compressor unit are as follows. The required capacity of other levels of compressor units is 0.

[0107] 8874 / 1.294=6858m 3 ·h -1 ;

[0108] 8874 / (1.294×15000)≈1.

[0109] After that, an additional compressor unit (the first-stage compressor unit at this time) is activated to compress the gas to P1 and then enter the previous single-stage compressor unit (the second-stage compressor unit at this time) to continue compressing it to the supply pressure P. When the ratio of the outlet pressure of the first-stage compressor unit 1.6MPa to the inlet pressure P2 is equal to the pressure ratio 2 of the compressor unit, the second step of gas extraction is completed. At this time, the pressure of all storage tanks is 0.8MPa, and the amount of gas extracted from each storage tank is:

[0110] (1.294-0.6488)×1103.65=712kg;

[0111] The second step gas supply time is:

[0112] To meet the gas supply demand, the required second-stage compressor unit inlet gas volume flow rate and the number of compressors in the second-stage compressor unit are as follows:

[0113] 8874 / 0.6488=13678m 3 ·h -1 ;

[0114] 8874 / (0.6488×15000)≈1.

[0115] Finally, the three-stage compressor is activated, and the gas taken out from each tank is:

[0116] (0.6488-0.3248)×1103.65=358kg;

[0117] The third step of gas supply time is:

[0118]

[0119] At this time, in order to meet the gas supply demand, the gas volume flow rate and number of the compressor inlet of the third-stage compressor unit are:

[0120] 8874 / 0.3248=27321m 3 ·h -1 ;

[0121] 8874 / (0.3248×15000)≈2.

[0122] The calculation results after each gas extraction step are summarized in Table 2.

[0123] Table 2 Summary of calculation results of traditional gas extraction methods

[0124]

[0125] When the hydrogen storage structure and gas extraction method of the present invention are used, assuming that the compressor unit includes M=3 levels, the gas extraction method is divided into seven steps.

[0126] In the first step, a single-stage compressor unit is used to extract gas from the first tank in the tank group. When the ratio of the supply pressure of 3.2 MPa to the inlet pressure is equal to the pressure ratio of the compressor unit 2, the first step of gas extraction is completed. At this time, the pressure of the first tank is 1.6 MPa, and the amount of gas extracted is:

[0127] (2.573-1.294)×1103.65=1412kg;

[0128] The first step of gas supply time is:

[0129]

[0130] At this time, in order to meet the gas supply demand, the volume flow rate and number of compressors of the single-stage compressor group are calculated by formula 3 and formula 4, which are 6858m 3 ·h -1 and 1.

[0131] In the second step, an additional compressor unit (called the first-stage compressor unit) is activated to continue taking gas from the first storage tank. After compressing the gas to 1.6MPa, it enters the previous single-stage compressor unit (called the second-stage compressor unit) and continues to compress it to a supply pressure of 3.2MPa. At the same time, the second compressor unit also starts to take gas from the second storage tank until the pressure of the second storage tank reaches 1.6MPa, completing the second step of gas extraction. At this time, the two-stage compressor unit is activated at the same time, and the pressures of the first and second storage tanks are 0.8MPa and 1.6MPa respectively. The gas extraction amount from the first and second storage tanks in the second step is calculated using Formula 5, which is 712.07kg and 1411.57kg respectively.

[0132] The second step gas supply time is:

[0133]

[0134] At this time, in order to meet the gas supply demand, the gas volume flow rate from the first tank to the first stage compressor unit is and the gas volume flow rate of the second storage tank directly into the second stage compressor unit By solving the following system of equations:

[0135]

[0136] Solved Therefore, the required first-stage compressor unit capacity configuration and number of compressors are calculated by Formula 3 and Formula 4, which are 4531m 3 ·h -1 Similarly, the capacity configuration and number of compressors of the second stage compressor unit are 6858m 3 ·h -1 and 1:

[0137] The gas extraction operations in the third, fourth and fifth steps are the same. The three-stage compressor unit is activated at the same time, and gas is extracted from three storage tanks at the same time. In order to meet the gas supply demand, the inlet gas volume flow rate of a single storage tank directly enters the m-th stage compressor unit without passing through other levels of compressor units By solving the following system of equations:

[0138]

[0139] Solved The required first-stage compressor unit capacity configuration and number of compressors are calculated by formula 3 and formula 4, respectively: 3937m 3 ·h -1 Similarly, the capacity configuration and number of compressors of the second stage compressor unit are 5896m 3 ·h -1 Similarly, the capacity configuration and number of compressors of the third stage compressor unit are the same as those of the second stage compressor unit in the second step, which are 6858m 3 ·h -1 and 1.

[0140] The calculation method for step 6 is similar to that for step 2 and will not be described in detail here. The calculation method for step 7 is similar to that for step 1. The calculation results after each step are summarized in Table 3.

[0141] Table 3 Summary of calculation results of cascade gas extraction method

[0142]

[0143]

[0144] Comparing the results in Table 2 and Table 3, when the traditional air extraction method completes the second step of air extraction and abandons the third step of air extraction, the cumulative air supply time is 1.2h, and the secondary compressor capacity of 13678m3 is required. 3 ·h -1 The capacity of the three-stage compressor is 6858m 3 ·h -1 When the fifth step of the cascade air extraction method is completed and the sixth and seventh steps are abandoned, the cumulative air supply time is 1.24h, and the capacity of the first-stage compressor required is 3937m 3 ·h -1 The capacity of the second stage compressor is 5896m 3 ·h -1 The capacity of the three-stage compressor is 6858m 3 ·h -1 , with a total capacity of 16691m 3 ·h -1 , requiring only 81.28% of the capacity required for traditional gas extraction, while increasing gas supply capacity by 3.33%. Therefore, compared to traditional gas extraction methods, the cascade gas extraction method achieves greater gas supply capacity with a smaller compressor capacity, offering significant economic advantages. The greater the number of storage tanks, the more economical the cascade gas extraction method.

[0145] On the other hand, when the rated capacity of the compressor is 15000m 3 ·h -1 When the traditional air extraction method completes the third step of air extraction, the cumulative air supply time is 1.4h, and two first-stage compressors, one second-stage compressor, and one third-stage compressor are required; when the cascade air extraction method completes the sixth step of air extraction, the cumulative air supply time is 1.36h, and only one first-stage, two-stage, and three-stage compressors are required. This shows that the cascade air extraction method can be equipped with one less first-stage compressor than the traditional air extraction method with only a 2.86% loss in air supply. As the number of storage tanks increases, the loss becomes smaller. When the rated capacity of the compressor decreases, the number of compressors that are less configured will be greater.

[0146] In addition, the calculation results of the two methods show that the use of the gas storage system and the stepped gas extraction method of the present invention can allow the system to have more pressure levels of gas at the same time. When the gas supply demand fluctuates, the gas storage system has a higher adjustment ability and a faster response ability, which can increase the flexibility of the gas storage system.

[0147] In summary, the gas storage system structure, tiered gas extraction method, and system configuration design method of the present invention offer advantages over traditional methods. The tiered gas extraction method allows for simultaneous extraction of gas from different pressure storage tanks, achieving comprehensive system energy utilization and reducing compressor capacity requirements compared to traditional gas extraction methods. The system capacity configuration method can be used for the optimized design of novel gas storage system structures, offering greater advancements.

[0148] In this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article or apparatus. The orientation or positional relationship indicated by the terms "upper", "lower", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0149] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention is not limited to any single aspect, nor to any single embodiment, nor to any combination and / or permutation of these aspects and / or embodiments. Each aspect and / or embodiment of the present invention can be used alone or in combination with one or more other aspects and / or other embodiments.

[0150] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the above-described embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above-described embodiments within the technical scope disclosed by the present invention, or replace some of the technical features therein with equivalents. Such modifications, changes, or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A gas extraction method, characterized in that: Using gas storage system to achieve: The gas storage system comprises: a storage tank group, a compressor group of a preset order, and a control device connected to the compressor group; Each storage tank in the storage tank group is individually connected to the inlet main line of each stage of the compressor unit; The control device is used to control the compressor unit to take gas from the storage tank group in a step-by-step gas-taking manner; The method comprises: Using a single-stage compressor unit to draw gas from the first tank in the tank group until the ratio of the gas supply pressure P to the inlet pressure is equal to the pressure ratio z1 of the compressor unit. After the first gas drawing operation is completed, the pressure of the first tank is P1. After the first gas extraction operation is completed, an additional compressor unit is activated to continue extracting gas from the first storage tank, compressing the gas to P1, and then entering the single-stage compressor unit to continue compressing it to the supply pressure P. The single-stage compressor unit is then used to extract gas from the second storage tank until the pressure in the second storage tank reaches P1. After the second gas extraction operation is completed, the pressure in the first storage tank is P2. Each time a gas extraction operation is performed, one more compressor unit is activated to extract gas until the preset number of compressor units are activated and the number of remaining storage tanks is not less than the preset number, and all compressor units are used to extract gas from the preset number of storage tanks at the same time; The gas extraction operation is carried out until the number of remaining storage tanks from which gas can be extracted is less than the preset number, and all the compressor units are used to extract gas from the remaining storage tanks from which gas can be extracted simultaneously, until the gas in all the storage tanks can no longer be extracted, and the gas extraction is terminated.

2. The gas extraction method according to claim 1, characterized in that: Each time an additional compressor unit is activated to take air, the original last-stage compressor unit becomes the second-stage compressor unit, the latest added compressor unit becomes the first-stage compressor unit, and the earliest activated compressor unit becomes the last-stage compressor unit.

3. The gas extraction method according to claim 2, characterized in that: In a gas extraction operation in which the compressor units of the preset order are activated simultaneously and the number of remaining storage tanks is not less than the preset order, and in a gas extraction operation before this, the inlet gas volume flow rate of a single storage tank directly entering the mth-stage compressor unit without passing through other-stage compressor units is determined by solving the following set of equations: Where, It represents the inlet gas volume flow rate of a single tank directly entering the mth level compressor unit without passing through other level compressor units, W represents the gas supply demand, P0 represents the maximum gas storage pressure of a single tank, ρ0 represents the density of the gas when the pressure is P0, P m represents the inlet pressure of the mth stage compressor unit after the mth step gas extraction operation, ρ m Indicates pressure as P m The density of the gas at R It represents the volume of a single storage tank, and M represents the number of compressor stages.

4. The gas extraction method according to claim 3, characterized in that: In a gas extraction operation in which the preset order of compressor units are simultaneously activated and the number of remaining storage tanks is not less than the preset order of gas, and in a gas extraction operation before this, the inlet gas volume flow rate of the compressor units is determined by the following formula: Where, It represents the total volume flow rate of the inlet gas of the m-th compressor unit, that is, the capacity configuration of the m-th compressor unit.

5. The gas extraction method according to claim 3, characterized in that: In a gas extraction operation in which the preset order of compressor groups are simultaneously activated and the number of remaining storage tanks is not less than the preset order of gas extraction, as well as in a gas extraction operation before this, the number of compressors in the compressor group is determined by the following formula: Where n m Indicates the number of compressors in the m-th compressor group, It represents the rated intake volume flow rate of a single compressor in the m-th stage compressor unit.

6. The gas extraction method according to claim 3, characterized in that: In the gas extraction operation in which the preset order of compressor units are simultaneously activated and the number of remaining storage tanks is not less than the preset order of magnitude, as well as in the gas extraction operation before this, the gas extraction volume of the storage tank is determined by the following formula: w m,m =(ρ m-1 -r m )V R m∈M,m=1,2,…M; Where w m,m represents the gas volume of the mth tank in the mth gas extraction operation, ρ m-1 Indicates pressure as P m-1 The density of the gas at m-1 It indicates the inlet pressure of the m-1th stage compressor unit after the m-1th step gas extraction operation.

7. The gas extraction method according to claim 3, characterized in that: In the gas extraction operation in which the preset order of compressor units are simultaneously activated and the number of remaining storage tanks is not less than the preset order of magnitude, and in the gas extraction operation before this, the gas supply time of the mth gas extraction operation is determined by the following formula: Among them, t m represents the gas supply time of the mth step gas extraction operation, ρ m-1 Indicates pressure as P m-1 The density of the gas at m-1 It indicates the inlet pressure of the m-1th stage compressor unit after the m-1th step gas extraction operation.

8. The gas extraction method according to claim 3, characterized in that: When the gas extraction operation is carried out until the number n of remaining storage tanks that can be extracted is less than the number M of compressor group stages, and the M-stage compressor groups are activated to extract gas from the remaining storage tanks that can be extracted, the total air intake flow rate of the n-th to m-th stage compressor groups is the same.

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