Series multi-stage compressor equipment for heat and mass energy storage and use method of series multi-stage compressor equipment

Abstract

The invention provides series multi-stage compressor equipment for heat and mass energy storage and a using method thereof, and relates to the technical field of energy storage. A one-way valve is arranged at an outlet of a compressor at the tail end of each compressor unit, reverse flowing of high-pressure fluid in the subsequent process of the compressor units can be avoided, the volume of a free flowing pipeline at the outlet of each compressor unit can be reduced, and therefore the risk of reverse flowing of the high-pressure fluid is further reduced. The pressure release valve is arranged at the outlet of the compressor at the tail end of each compressor unit, so that the pressure at the outlet position of the compressor unit can be quickly released, the pressure release shutdown speed of the compressor unit is increased, and meanwhile, the reverse inflow damage of high-pressure fluid to the compressor unit in the accident shutdown working condition is avoided; by reasonably arranging the auxiliary loop and the regulating valve, the technical and operation difficulty of parameter matching of the multiple compressor units in the starting and stopping process can be effectively reduced, so that the starting and stopping speed of the compressor units is increased, and meanwhile, the probability of unfavorable operation working conditions such as surge caused by mismatching of operation parameters is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage, and particularly to a series multi-stage compressor device for thermal mass energy storage and a method for using the same. Background Art

[0002] Energy storage is one of the key support technologies for China's energy transformation strategy. Among them, large-capacity long-duration energy storage technology is particularly important for peak-valley regulation of the power system and centralized grid connection and consumption of wind power and photovoltaic power generation. Compressed air energy storage is a typical new large-capacity long-duration energy storage technology. This technology uses electric energy to drive an air compressor, compresses ambient air to high temperature and high pressure, and then sends it into a heat exchanger to exchange heat with a heat storage medium. After releasing heat and cooling, it enters a gas storage tank for storage. The heat storage medium absorbs heat and rises in temperature and then enters a heat accumulator for storage. Thus, electric energy is converted into two parts: the energy release of compressed air and the heat energy of the heat storage medium, realizing the large-capacity long-duration storage of electric energy.

[0003] The compressor unit is the key equipment for realizing the electric energy input of the compressed air energy storage system. The unit volume mass of air is small, so the energy that can be carried per unit volume is small. In order to improve the energy storage density of the system, in practical applications, it is necessary to continuously compress the ambient atmospheric air multiple times to greatly increase the air pressure, so that the energy contained per unit volume is increased. At the same time, the gas storage capacity of the system gas storage equipment can also be increased, thereby improving the energy storage density and energy storage capacity of the system. The main compressors for large-capacity compressed air energy storage systems are speed-type compressors such as centrifugal and axial-flow compressors. Due to the limitations of the working principle and process level, the single-stage compression ratio of speed-type compressors is small, and the gas boosting ability is limited. To output a higher air pressure, multiple compressors need to be connected in series for continuous compression. And the number of compressors that can be integrated in a single compressor unit is also limited by factors such as geometric structure and drive motor power. Therefore, in order to achieve high-pressure air supply, the series connection of multiple compressor units has also become the main development trend.

[0004] As an energy storage equipment in the power system, the compressed air energy storage system should have the ability of quick start-stop and regulation. At the same time, it needs to start and stop frequently, which also puts forward the requirements of quick and frequent start-stop and regulation for multiple and multi-stage series-connected compressor units. However, the operation of speed-type compressors has strict requirements for parameter regulation. The quick start and regulation of the unit or parameter mismatch are likely to cause the unit to enter adverse working conditions such as surge, and then lead to accidents. This risk is more significant when multiple units are connected in series. To achieve efficient start-stop and regulation of multiple and multi-stage compressor units and ensure the safe and stable operation of the units, on the one hand, innovation in system technology is required, and at the same time, the operation regulation method needs to be optimized, so as to further realize the series operation of multi-stage compressor units on the basis of the original flow rate and anti-surge regulation mechanism of the compressor unit. Summary of the Invention

[0005] The present invention provides a series multi-stage compressor device for thermophysical energy storage, which is used to solve the problems existing in the prior art, such as the risk of reverse flow of high-pressure fluid, the difficulty of starting and stopping operations, and the surging of the compressor unit.

[0006] The present invention provides a series multi-stage compressor device for thermophysical energy storage, including: Multiple groups of compressor units, which are connected in series in sequence. Each compressor unit includes a driving machine and multiple compressors, and the multiple compressors are connected in series in sequence. The multiple compressors are driven by the same driving machine; a check valve and a pressure relief valve are arranged at the outlet of the compressor at the end of each group of compressor units. The check valve is used to connect the inlet of the compressor at the head end of the next group of compressor units or subsequent process equipment, and the pressure relief valve is used to relieve pressure; except for the first group of compressor units, the outlet of the compressor at the end of the remaining compressor units is communicated with the inlet of the compressor at the head end through an auxiliary circuit, and a regulating valve is arranged on the auxiliary circuit.

[0007] According to the series multi-stage compressor device for thermophysical energy storage provided by the present invention, in adjacent two groups of compressor units, the outlet of the compressor at the end of the previous group of compressor units is communicated with the inlet of the compressor at the head end of the next group of compressor units through a connecting pipeline, and the check valve is connected in series in the connecting pipeline.

[0008] According to the series multi-stage compressor device for thermophysical energy storage provided by the present invention, the check valve is located at one end of the connecting pipeline close to the compressor at the end of the previous group of compressor units.

[0009] According to the series multi-stage compressor device for thermophysical energy storage provided by the present invention, the connecting pipeline between the check valve and the outlet of the compressor at the end of the compressor unit is communicated with the pressure relief valve.

[0010] According to the series multi-stage compressor device for thermophysical energy storage provided by the present invention, it further includes: At least three groups of heat exchanger components, which are connected in series with the compressor unit.

[0011] According to the series multi-stage compressor device for thermophysical energy storage provided by the present invention, each heat exchanger component includes at least one heat exchanger, and the heat exchanger is connected in series between adjacent two compressors.

[0012] According to the series multi-stage compressor device for thermophysical energy storage provided by the present invention, the rotating shafts of the multiple compressors in the same group of compressor units are connected in series in sequence, and the rotating shaft of the driving machine is connected with the rotating shaft of the compressor at the head end.

[0013] A series multi-stage compressor device for thermal mass energy storage provided by the present invention, wherein the pressure relief valve is arranged at the outlet near the corresponding end compressor.

[0014] The present invention also provides a usage method of a series multi-stage compressor device for thermal mass energy storage. The usage method is based on the series multi-stage compressor device for thermal mass energy storage described in any one of the above, and includes: Starting method: fully open the opening degrees of the pressure relief valve and the regulating valve of each compressor unit, start the drive of the first group of the compressor units, and gradually reduce the opening degree of the pressure relief valve of the first group of the compressor units. The outlet pressure of the first group of the compressor units gradually increases and starts to supply gas to the second group of the compressor units; after the inlet pressure of the second group of the compressor units reaches the starting pressure, start the drive of the second group of the compressor units, and gradually reduce the opening degrees of the pressure relief valve and the regulating valve of the second group of the compressor units. The outlet pressure of the second group of the compressor units gradually increases and starts to supply gas to the third group of the compressor units; then start the remaining compressor units in sequence according to the above method, establish the pressure ratio successively from the first group of the compressor units to the last group of the compressor units. After the pressure relief valve and the regulating valve of the last group of the compressor units are closed, the last group of the compressor units enters the state of stably supplying gas to the subsequent process equipment, and the starting process is completed; Shutdown method: in the order from the last group of the compressor units to the first group of the compressor units, open the opening degree of the pressure relief valve of each compressor unit to the fully open state; gradually open the opening degree of the regulating valve of each compressor unit to the fully open state to avoid surge caused by insufficient intake air flow of the corresponding compressor unit; close the drive of each compressor unit in the order from the last group of the compressor units to the first group of the compressor units, and each compressor unit enters the inertial coasting state; after the inertial coasting of each compressor unit ends, close the pressure relief valve and the regulating valve of each compressor unit, and the shutdown process is completed.

[0015] The usage method of a series multi-stage compressor device for thermal mass energy storage provided by the present invention further includes: Emergency shutdown method: when the drive of at least one group of the compressor units stops driving due to abnormal factors, immediately cut off the power sources of all drives, and at the same time open the opening degree of the pressure relief valve of each compressor unit to the fully open state; gradually open the opening degree of the regulating valve of each compressor unit to the fully open state to avoid surge caused by insufficient intake air flow of the corresponding compressor unit; after the inertial coasting of each compressor unit ends, close the pressure relief valve and the regulating valve of each compressor unit, and the emergency shutdown process is completed.

[0016] The series multi-stage compressor equipment for thermo-mass energy storage provided by the present invention is equipped with check valves at the outlets of the compressors at the ends of each group of compressor units, which can not only prevent the reverse flow of high-pressure fluid in the subsequent processes of the compressor units, but also reduce the volume of the free-flow pipeline at the outlets of the compressor units, thereby further reducing the risk of reverse flow of high-pressure fluid. By installing pressure relief valves at the outlets of the compressors at the ends of each group of compressor units, rapid pressure relief at the outlet positions of the compressor units can be achieved, thus accelerating the pressure relief and shutdown speed of the compressor units, and at the same time avoiding the reverse inflow damage of high-pressure fluid to the compressor units in the accident shutdown condition. By reasonably setting the auxiliary circuit and regulating valves, the technical and operational difficulties of parameter matching of multiple compressor units during startup and shutdown can be effectively reduced, thereby accelerating the startup and shutdown speed of the compressor units, and at the same time reducing the probability of adverse operating conditions such as surging caused by unmatched operating parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 FIG. is a schematic structural diagram of a series multi-stage compressor equipment for thermo-mass energy storage provided by an embodiment of the present invention.

[0019] Figure 2 FIG. is a schematic structural diagram of a series multi-stage compressor equipment for thermo-mass energy storage provided by another embodiment of the present invention.

[0020] Reference Signs: LC, low-pressure compressor unit; LM, low-pressure driver; LC1-1, first low-pressure compressor; LC1-2, second low-pressure compressor; LC1-3, third low-pressure compressor; LH1-1, first low-pressure heat exchanger; LH1-2, second low-pressure heat exchanger; LH1-3, third low-pressure heat exchanger; LA, low-pressure pressure relief valve; LF, low-pressure check valve; LL, low-pressure connecting pipeline; MC, medium-pressure compressor unit; MM, medium-pressure driver; MC1-1, first medium-pressure compressor; MC1-2, second medium-pressure compressor; MC1-3, third medium-pressure compressor; MH1-1, first medium-pressure heat exchanger; MH1-2, second medium-pressure heat exchanger; MH1-3, third medium-pressure heat exchanger; MA, medium-pressure pressure relief valve; MF, medium-pressure check valve; MR, medium-pressure regulating valve; ML, medium-pressure connecting pipeline; HC, high-pressure compressor unit; HM, high-pressure driver; HC1-1, the first high-pressure compressor; HC1-2, the second high-pressure compressor; HH1-1, the first high-pressure heat exchanger; HH1-2, the second high-pressure heat exchanger; HA, high-pressure relief valve; HF, high-pressure check valve; HR, high-pressure regulating valve; HL, high-pressure connecting pipeline. Detailed implementation manners

[0021] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0022] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0023] In the description of the embodiments of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific situations.

[0024] In the embodiments of the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or simply indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or simply indicates that the first feature has a lower horizontal height than the second feature.

[0025] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0026] As Figure 1 shown, the series multi-stage compressor device for thermal mass energy storage includes multiple groups of compressor units, and the multiple groups of compressor units are connected in series in sequence. Each compressor unit includes a driving machine and multiple compressors, and the multiple compressors are connected in series in sequence. The multiple compressors are driven by the same driving machine; a check valve and a pressure relief valve are provided at the outlet of the compressor at the end of each group of compressor units. The check valve is used to connect the inlet of the compressor at the head of the next group of compressor units or subsequent process equipment, and the pressure relief valve is used to release pressure; except for the first group of compressor units, the outlet of the compressor at the end of the remaining compressor units is communicated with the inlet of the compressor at the head through an auxiliary circuit, and a regulating valve is provided in the auxiliary circuit.

[0027] It should be noted here that the multiple groups of compressor units being connected in series in sequence means that in two adjacent groups of compressor units, the outlet of the compressor at the end of the previous group of compressor units is communicated with the inlet of the compressor at the head of the next group of compressor units. The multiple compressors being connected in series in sequence means that in two adjacent compressors, the outlet of the previous compressor is communicated with the inlet of the next compressor.

[0028] For the series multi-stage compressor device for thermal mass energy storage provided by the present invention, by providing a check valve at the outlet of the compressor at the end of each group of compressor units, it can not only prevent the reverse flow of high-pressure fluid in the subsequent process of the compressor unit, but also reduce the volume of the free-flow pipeline at the outlet of the compressor unit, thereby further reducing the risk of reverse flow of high-pressure fluid; by providing a pressure relief valve at the outlet of the compressor at the end of each group of compressor units, the rapid release of pressure at the outlet position of the compressor unit can be realized, thereby accelerating the pressure relief and shutdown speed of the compressor unit, and at the same time avoiding the reverse inflow damage of high-pressure fluid to the compressor unit in the accident shutdown condition; by reasonably setting the auxiliary circuit and the regulating valve, the technical and operation difficulties of parameter matching of multiple compressor units during startup and shutdown can be effectively reduced, thereby accelerating the startup and shutdown speed of the compressor unit, and at the same time reducing the probability of adverse operating conditions such as surging caused by mismatched operating parameters.

[0029] In a specific embodiment of the present invention, as Figure 1As shown in the figure, the series multi-stage compressor equipment for thermophysical energy storage includes a low-pressure compressor unit LC, a medium-pressure compressor unit MC, and a high-pressure compressor unit HC connected in series in sequence. Among them, the low-pressure compressor unit LC includes a first low-pressure compressor LC1-1, a second low-pressure compressor LC1-2, and a third low-pressure compressor LC1-3 connected in series in sequence. The medium-pressure compressor unit MC includes a first medium-pressure compressor MC1-1, a second medium-pressure compressor MC1-2, and a third medium-pressure compressor MC1-3 connected in series in sequence. The high-pressure compressor unit HC includes a first high-pressure compressor HC1-1 and a second high-pressure compressor HC1-2 connected in series in sequence.

[0030] It should be noted here that the number of compressor units is not limited to three groups, and can also be four groups, five groups or more, which is specifically determined according to actual needs. The number of compressors in the compressor unit is not limited to two or three, and can also be four, five or more, which is specifically determined according to actual needs.

[0031] Furthermore, a low-pressure check valve LF and a low-pressure relief valve LA are provided at the outlet of the third low-pressure compressor LC1-3. A medium-pressure check valve MF and a medium-pressure relief valve MA are provided at the outlet of the third medium-pressure compressor MC1-3. A high-pressure check valve HF and a high-pressure relief valve HA are provided at the outlet of the second high-pressure compressor HC1-2.

[0032] Furthermore, the outlet of the third medium-pressure compressor MC1-3 is communicated with the inlet of the first medium-pressure compressor MC1-1 through a medium-pressure auxiliary circuit, and a medium-pressure regulating valve MR is provided in the medium-pressure auxiliary circuit. The outlet of the second high-pressure compressor HC1-2 is communicated with the inlet of the first high-pressure compressor HC1-1 through a high-pressure auxiliary circuit, and a high-pressure regulating valve HR is provided in the high-pressure auxiliary circuit.

[0033] In a specific embodiment of the present invention, as Figure 1 shown, the rotating shafts of multiple compressors in the same group of compressor units are connected in series in sequence, and the rotating shaft of the driving machine is connected to the rotating shaft of the compressor at the head end. Specifically, the low-pressure driving machine LM is connected to the rotating shaft of the first low-pressure compressor LC1-1, the medium-pressure driving machine MM is connected to the rotating shaft of the first medium-pressure compressor MC1-1, and the high-pressure driving machine HM is connected to the rotating shaft of the first high-pressure compressor HC1-1 or the second high-pressure compressor HC1-2.

[0034] In a specific embodiment of the present invention, the relief valve is provided near the outlet of the corresponding terminal compressor.

[0035] In a specific embodiment of the present invention, between two adjacent groups of compressor units, the outlet of the compressor at the end of the previous group of compressor units is communicated with the inlet of the compressor at the head end of the next group of compressor units through a connecting pipeline, and a check valve is connected in series in the connecting pipeline.

[0036] Specifically, as Figure 1 shown, the outlet of the third low-pressure compressor LC1-3 is communicated with the inlet of the first medium-pressure compressor MC1-1 through a low-pressure connecting pipeline LL, and a low-pressure check valve LF is connected in series in the low-pressure connecting pipeline LL. The outlet of the third medium-pressure compressor MC1-3 is communicated with the inlet of the first high-pressure compressor HC1-1 through a medium-pressure connecting pipeline ML, and a medium-pressure check valve MF is connected in series in the medium-pressure connecting pipeline ML. The outlet of the second high-pressure compressor HC1-2 is communicated with subsequent process equipment through a high-pressure connecting pipeline HL, and a high-pressure check valve HF is connected in series in the high-pressure connecting pipeline HL.

[0037] In an embodiment of the present invention, the check valve is located at one end of the connecting pipeline close to the compressor at the end of the previous set of compressor units. Specifically, as Figure 1 shown, the low-pressure check valve LF is located at one end of the low-pressure connecting pipeline LL close to the third low-pressure compressor LC1-3, the medium-pressure check valve MF is located at one end of the medium-pressure connecting pipeline ML close to the third medium-pressure compressor MC1-3, and the high-pressure check valve HF is located at one end of the high-pressure connecting pipeline HL close to the second high-pressure compressor HC1-2. By arranging the positions of the check valves as close as possible to the compressor at the end of the previous set of compressor units, the volume of the pipeline between the outlet of the compressor at the end and the check valve can be minimized as much as possible. When the compressor shuts down normally and due to an accident (abnormal shutdown), the reverse impact of the high-pressure fluid in this part of the connecting pipeline on the corresponding compressor at the end can be weakened to the greatest extent, thereby reducing the possibility of damage to the compressor unit caused by the backflow of the high-pressure fluid.

[0038] In an embodiment of the present invention, the connecting pipeline between the check valve and the outlet of the compressor at the end of the compressor unit is communicated with a pressure relief valve, that is, the pressure relief valve is arranged in the connecting pipeline between the check valve and the outlet of the compressor at the end of the compressor unit. Specifically, as Figure 1 shown, a low-pressure pressure relief valve LA is arranged in the low-pressure connecting pipeline LL between the low-pressure check valve LF and the outlet of the third low-pressure compressor LC1-3, a medium-pressure pressure relief valve MA is arranged in the medium-pressure connecting pipeline ML between the medium-pressure check valve MF and the outlet of the third medium-pressure compressor MC1-3, and a high-pressure pressure relief valve HA is arranged in the high-pressure connecting pipeline HL between the high-pressure check valve HF and the outlet of the second high-pressure compressor HC1-2.

[0039] The pressure relief valve can be arranged before or after the corresponding check valve, but should be as close as possible to the outlet of the corresponding compressor at the end to quickly release the pressure at the outlet of the corresponding compressor at the end during normal shutdown or accident shutdown, further ensuring that the backflow of high-pressure fluid will not occur. Considering the optimal function of the pressure relief valve, Figure 1In the illustrated embodiment, each pressure relief valve is arranged before the corresponding check valve to reduce the amount of high-pressure fluid discharged by the pressure relief valve, thereby achieving a better rapid pressure relief effect. To ensure the pressure relief effect, the pressure relief valve has the ability to quickly start and fully open, and the time from fully closed start to full open should not exceed 5 seconds. Preferably, the opening time is 2 to 5 seconds. At the same time, the diameter of the pressure relief valve and the pressure relief pipeline where it is located should not be less than the diameter of the connected process pipeline to avoid throttling pressure relief.

[0040] According to requirements, each compressor unit should be equipped with a flow regulation and surge regulation mechanism to ensure the safe and stable operation of the compressor unit. The purpose of setting the pressure relief valve in the present invention is to quickly discharge the pressure at the outlet of the compressor unit to a low-pressure environment and prevent high-pressure fluid from flowing back in the compressor unit.

[0041] In a specific embodiment of the present invention, the series-connected multi-stage compressor equipment for thermo-mass energy storage further includes at least three groups of heat exchanger assemblies. Each group of heat exchanger assemblies includes at least one heat exchanger, and the heat exchanger assemblies are connected in series with the compressor unit. The heat exchanger assemblies are used to exchange heat between the heat exchange medium and the compressed air. Considering that there may be condensation such as moisture after the compressed air cools down, the heat exchanger group is provided with a condensate separation and discharge mechanism.

[0042] In a specific embodiment of the present invention, the heat exchanger assembly includes at least one heat exchanger, and the heat exchanger is connected in series between two adjacent compressors. Specifically, as Figure 1 shown, the series-connected multi-stage compressor equipment for thermo-mass energy storage includes three groups of heat exchanger assemblies, namely a low-pressure heat exchanger assembly, a medium-pressure heat exchanger assembly, and a high-pressure heat exchanger assembly. Among them, the low-pressure heat exchanger assembly includes a first low-pressure heat exchanger LH1-1, a second low-pressure heat exchanger LH1-2, and a third low-pressure heat exchanger LH1-3. The first low-pressure heat exchanger LH1-1 is connected in series between the first low-pressure compressor LC1-1 and the second low-pressure compressor LC1-2. The second low-pressure heat exchanger LH1-2 is connected in series between the second low-pressure compressor LC1-2 and the third low-pressure compressor LC1-3. The third low-pressure heat exchanger LH1-3 is connected in series to the low-pressure connection pipeline LL between the third low-pressure compressor LC1-3 and the first medium-pressure compressor MC1-1.

[0043] The medium-pressure heat exchanger assembly includes a first medium-pressure heat exchanger MH1-1, a second medium-pressure heat exchanger MH1-2, and a third medium-pressure heat exchanger MH1-3. The first medium-pressure heat exchanger MH1-1 is connected in series between the first medium-pressure compressor MC1-1 and the second medium-pressure compressor MC1-2. The second medium-pressure heat exchanger MH1-2 is connected in series between the second medium-pressure compressor MC1-2 and the third medium-pressure compressor MC1-3. The third medium-pressure heat exchanger MH1-3 is connected in series to the medium-pressure connection pipeline ML between the third medium-pressure compressor MC1-3 and the first high-pressure compressor HC1-1.

[0044] The high-pressure heat exchanger assembly includes a first high-pressure heat exchanger HH1-1 and a second high-pressure heat exchanger HH1-2. The first high-pressure heat exchanger HH1-1 is connected in series between a first high-pressure compressor HC1-1 and a second high-pressure compressor HC1-2, and the second high-pressure heat exchanger HH1-2 is connected in series to a high-pressure connecting pipeline HL between the second high-pressure compressor HC1-2 and subsequent process equipment.

[0045] It should be noted here that the installation position of the heat exchanger is not limited to this. It is also possible to install heat exchangers only behind some compressors, only behind the compressors at each end, or only behind one set of compressor units. Each heat exchanger is installed behind the corresponding check valve to reduce the pipeline volume in front of the check valve, thereby reducing the impact of the reverse flow of high-pressure fluid in the pipeline volume.

[0046] In a specific embodiment of the present invention, the exhaust gas temperature of the compressors at each end is lower than the maximum allowable intake temperature of the corresponding compressor at the head end. Therefore, the exhaust end interface of the medium-pressure auxiliary circuit is connected to a low-pressure connecting pipeline LL between the third low-pressure heat exchanger LH1-3 and the inlet of the first medium-pressure compressor MC1-1 to shorten the return flow path. Similarly, the exhaust end interface of the high-pressure auxiliary circuit is connected to a medium-pressure connecting pipeline ML between the third low-pressure heat exchanger LH1-3 and the inlet of the first high-pressure compressor HC1-1 and is as close as possible to the inlet of the first high-pressure compressor HC1-1.

[0047] In another embodiment of the present invention, as Figure 2 shown, the exhaust gas temperature of the compressors at the end of each compressor unit is higher than the maximum allowable intake temperature of the corresponding compressor at the head end. Therefore, the difference between this embodiment and the above embodiment is that the exhaust end interface of the medium-pressure auxiliary circuit is connected to a low-pressure connecting pipeline LL between the third low-pressure heat exchanger LH1-3 and the low-pressure check valve LF; similarly, the exhaust end interface of the high-pressure auxiliary circuit is connected to a medium-pressure connecting pipeline ML between the third medium-pressure heat exchanger MH1-3 and the medium-pressure check valve MF.

[0048] The present invention also provides a method for using a series multi-stage compressor device for thermo-mass energy storage. The method for using is based on the series multi-stage compressor device for thermo-mass energy storage described in any one of the above embodiments, and includes: Startup method: fully open the opening degrees of the pressure relief valves and regulating valves of each set of compressor units, start the driver of the first set of compressor units, and gradually reduce the opening degree of the pressure relief valve of the first set of compressor units. The outlet pressure of the first set of compressor units gradually increases and starts to supply gas to the second set of compressor units. After the inlet pressure of the second set of compressor units reaches the startup pressure, start the driver of the second set of compressor units and gradually reduce the opening degrees of the pressure relief valve and regulating valve of the second set of compressor units. The outlet pressure of the second set of compressor units gradually increases and starts to supply gas to the third set of compressor units. Then, start the remaining compressor units in sequence according to the above method, establish the pressure ratio successively from the first set of compressor units to the last set of compressor units. After the pressure relief valve and regulating valve of the last set of compressor units are closed, the last set of compressor units enters the state of stably supplying gas to the subsequent process equipment, and the startup process is completed.

[0049] Specifically, when the multi-stage compressor units are started in series, it should be ensured that the pressure relief valves and regulating valves of each set of compressor units are in the fully open state. Start the low-pressure driver LM to drive the first low-pressure compressor LC1-1, the second low-pressure compressor LC1-2, and the third low-pressure compressor LC1-3 to synchronously increase the speed and start to suck air from the environment. The gas is successively compressed by the first low-pressure compressor LC1-1 and cooled by the first low-pressure heat exchanger LH1-1, then continuously compressed by the second low-pressure compressor LC1-2 and cooled again by the first low-pressure heat exchanger LH1-1, and then further compressed by the third low-pressure compressor LC1-3 and further cooled by the first low-pressure heat exchanger LH1-1, and then directly discharged into the environment through the low-pressure pressure relief valve LA. At this time, gradually close the low-pressure pressure relief valve LA to make the pressure at the outlet of the third low-pressure compressor LC1-3 gradually rise. When the startup pressure difference is established between the pressure here and the pressure behind the low-pressure check valve LF, the low-pressure compressor unit LC starts to supply gas to the medium-pressure compressor unit MC.

[0050] After the start-up pressure is reached at the inlet of the first medium-pressure compressor MC1-1, start the medium-pressure driver MM to drive the first medium-pressure compressor MC1-1, the second medium-pressure compressor MC1-2, and the third medium-pressure compressor MC1-3 to increase their speeds synchronously and start compressing the incoming gas. After the gas is compressed by the first medium-pressure compressor MC1-1 and cooled by the first medium-pressure heat exchanger MH1-1 in sequence, it is further compressed by the second medium-pressure compressor MC1-2 and cooled again by the second medium-pressure heat exchanger MH1-2, and then further compressed by the third medium-pressure compressor MC1-3 and further cooled by the third medium-pressure heat exchanger MH1-3. Part of the gas is directly discharged into the environment through the medium-pressure relief valve MA; since part of the exhaust gas of the low-pressure compressor unit LC is discharged to the environment through the low-pressure relief valve LA, the gas supply flow rate to the medium-pressure compressor unit MC is small. To ensure the intake gas flow rate of the medium-pressure compressor unit MC during operation, at this time, part of the high-pressure gas at the outlet of the third medium-pressure compressor MC1-3 flows back to the inlet of the first medium-pressure compressor MC1-1 through the medium-pressure auxiliary circuit to ensure that the intake gas flow rate of the medium-pressure compressor unit MC is sufficient and will not cause surge. During this process, gradually close the medium-pressure relief valve MA to gradually increase the pressure at the outlet of the third medium-pressure compressor MC1-3. At the same time, since the low-pressure relief valve LA is gradually closed, the gas supply flow rate of the low-pressure compressor unit LC delivered to the medium-pressure compressor unit MC gradually increases. Therefore, it is necessary to gradually reduce the opening degree of the medium-pressure regulating valve MR to adjust the intake gas flow rate of the medium-pressure compressor unit MC through the medium-pressure auxiliary circuit to avoid adverse conditions such as surge of the compressor unit caused by the mismatch of the gas flow rate parameters between the medium-pressure compressor unit MC and the low-pressure compressor unit LC.

[0051] After the pressure gradually rises at the outlet of the third medium-pressure compressor MC1-3, the compressed gas begins to flow through the medium-pressure check valve MF towards the high-pressure compressor unit HC. When the starting pressure is reached at the inlet of the first high-pressure compressor HC1-1, the high-pressure drive motor HM is started, which drives the first high-pressure compressor HC1-1 and the second high-pressure compressor HC1-2 to increase their speeds synchronously and start compressing the incoming gas. After the gas is compressed by the first high-pressure compressor HC1-1 and cooled by the first high-pressure heat exchanger HH1-1, it is further compressed by the second high-pressure compressor HC1-2 and cooled again by the second high-pressure heat exchanger HH1-2. Part of the gas is directly discharged into the environment through the high-pressure relief valve HA; since part of the exhaust gas of the medium-pressure compressor unit MC is discharged to the environment through the medium-pressure relief valve MA, the gas flow rate delivered to the high-pressure compressor unit HC is relatively small. To ensure the intake gas flow rate required for the operation of the high-pressure compressor unit HC, at this time, part of the high-pressure gas at the outlet of the second high-pressure compressor HC1-2 flows back to the inlet of the first high-pressure compressor HC1-1 through the high-pressure auxiliary circuit to ensure that the intake gas flow rate of the high-pressure compressor unit HC is sufficient and will not cause surging; similarly, during this process, the high-pressure relief valve HA and the high-pressure regulating valve HR are gradually closed to gradually increase the pressure at the outlet of the second high-pressure compressor HC1-2, and at the same time, the intake gas flow rate of the medium-pressure compressor unit MC is adjusted through the high-pressure auxiliary circuit to avoid adverse conditions such as surging of the compressor unit caused by the mismatch of the gas flow rate parameters between the high-pressure compressor unit HC and the medium-pressure compressor unit MC. According to the above starting method, the low-pressure, medium-pressure, and high-pressure compressor units will sequentially establish the working pressure ratio. After that, in the order of low-pressure, medium-pressure, and high-pressure, on the premise of ensuring that each compressor unit does not surge, the relief valves and the regulating valves of the auxiliary circuits are gradually and cooperatively fully closed, and the three series-connected compressor units enter the normal working state, and the high-pressure check valve HF supplies gas to the gas storage tank or the subsequent process equipment at full load, and the starting process is completed.

[0052] Shutdown method: In the order from the last compressor unit group to the first compressor unit group, open the opening degree of the relief valve of each compressor unit group to the fully open state; gradually open the opening degree of the regulating valve of each compressor unit group to the fully open state to avoid surging caused by insufficient intake gas flow rate of the corresponding compressor unit; close the drive motor of each compressor unit group in the order from the last compressor unit group to the first compressor unit group, and each compressor unit group enters the inertial coasting state; after the inertial coasting of each compressor unit group ends, close the relief valve and the regulating valve of each compressor unit group, and the shutdown process is completed.

[0053] When the multi-stage compressor unit shuts down in series, in the order from high pressure, medium pressure to low pressure, gradually open the high-pressure relief valve HA, medium-pressure relief valve MA, and low-pressure relief valve LA to the fully open position, so that each compressor unit starts to release pressure. The opening speed of each relief valve needs to ensure that each compressor unit still operates below the surge curve, so it is not opened to the fully open position at the maximum designed opening speed. After the relief valve of the previous group of compressor units starts, the supply air pressure and flow rate to the next group of compressor units both decrease, which may cause the operation of the next group of compressor units to become unstable. To avoid adverse operating conditions, while opening each relief valve, by monitoring the operating curves of each compressor unit, gradually open the medium-pressure regulating valve MR and high-pressure regulating valve HR, and adjust the intake air flow rate of the high-pressure compressor unit HC and medium-pressure compressor unit MC by means of high-pressure fluid reflux, so as to avoid the surge condition caused by insufficient intake air. After the above operations enter the execution state, in the order from high pressure, medium pressure to low pressure, gradually close the high-pressure relief valve HA, medium-pressure relief valve MA, and low-pressure relief valve LA. After each compressor unit loses the driving force, it enters the coasting state under the action of inertia. At this time, each compressor is still compressing gas, and the outlet pressure of the compressor at the end of each compressor unit is significantly higher than the inlet pressure of the compressor at the head end, and there may still be a surge or even a phenomenon of high-pressure fluid backflow, and there may also be a phenomenon that the inlet of the next group of compressor units is lower than the ambient pressure due to insufficient gas supply from the previous group of compressor units. Therefore, it is necessary to keep each relief valve in the fully open state, and continue to monitor and adjust the opening of each auxiliary circuit according to the operating curves of each compressor unit to ensure that the compressor unit does not enter the adverse operating condition area until the coasting ends, and then close each relief valve to prevent ambient gas from flowing back into the unit, and the shutdown process is completed.

[0054] In a specific embodiment of the present invention, the method for using the series multi-stage compressor equipment for thermo-mass energy storage further includes: Emergency shutdown method: When the driving machine of at least one group of compressor units stops driving due to abnormal factors, immediately cut off the power source of all driving machines, and at the same time open the relief valve opening of each group of compressor units to the fully open state; gradually open the opening of the regulating valve of each group of compressor units to the fully open state to avoid surge caused by insufficient intake air flow rate of the corresponding compressor unit; after the coasting of each group of compressor units ends, close the relief valve and regulating valve of each group of compressor units, and the emergency shutdown process is completed.

[0055] It should be noted here that the stop here includes the automatic stop or emergency manual stop of the driving machine.

[0056] When an emergency shutdown occurs due to external factors or single compressor unit factors, each compressor unit will automatically disengage from the drive or requires rapid manual operation to disengage from the drive. At this time, it is extremely easy for high-pressure fluid reverse flow impact to occur, resulting in damage to the life of the compressor unit or even direct damage. To minimize the adverse effects on the compressor unit during the emergency shutdown process, after each compressor unit emergently disengages from the drive, the pressure relief valves should be immediately opened to the fully open position at the fastest designed opening speed. This process takes about 2 - 5 seconds. At this time, since check valves are provided at the air outlets of the compressors at the ends of each group of compressor units and the positions of the check valves and pressure relief valves are optimized, the pipe volume at the outlet of each group of compressor units has been reduced to the lowest level. Therefore, the high-pressure fluid therein can be quickly discharged to the external low-pressure environment, thereby ensuring that the pressure at the outlet of each compressor unit will not generate reverse flow impact. At the same time, similar to the normal shutdown process, to further eliminate the possibility of surge or even high-pressure fluid reverse flow phenomenon, and the phenomenon that the inlet pressure of the latter compressor unit is lower than the ambient pressure, under the condition of keeping each pressure relief valve fully open, the opening degrees of each auxiliary circuit are synchronously monitored and adjusted according to the operating curves of each compressor unit until the idling ends, and then each pressure relief valve is closed to prevent ambient gas from flowing back into the compressor unit, and the emergency shutdown process is completed.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-stage compressor device in series for thermal mass energy storage, characterized in that: include: A plurality of compressor groups, wherein the plurality of compressor groups are connected in series in sequence, the compressor groups include a driving machine and a plurality of compressors, the plurality of compressors are connected in series in sequence, and the plurality of compressors are driven by the same driving machine; a one-way valve and a pressure relief valve are provided at the outlet of the compressor at the end of each compressor group, the one-way valve is used to connect to the inlet of the compressor at the head end of the next compressor group or the subsequent process equipment, and the pressure relief valve is used to release pressure; except for the first compressor group, the outlets of the compressors at the ends of the remaining compressor groups are connected to the inlet of the compressor at the head end through an auxiliary circuit, and the auxiliary circuit is provided with a regulating valve.

2. The series-connected multi-stage compressor device for thermal mass energy storage according to claim 1, characterized in that: In two adjacent groups of compressor sets, the outlet of the compressor at the end of the previous group of compressor sets is connected to the inlet of the compressor at the head end of the next group of compressor sets through a connecting pipeline, and the one-way valve is serially connected to the connecting pipeline.

3. The series-connected multi-stage compressor device for thermal mass energy storage according to claim 1, characterized in that: The one-way valve is located at one end of the connecting pipeline close to the end of the previous compressor group.

4. The cascaded multi-stage compressor device for thermal mass energy storage according to claim 1, characterized in that: The connecting pipeline between the one-way valve and the compressor outlet at the end of the compressor unit is in communication with the pressure relief valve.

5. The multi-stage compressor device in series for thermal mass energy storage according to any one of claims 1 to 4, characterized in that: Also includes: At least three groups of heat exchanger assemblies, wherein the heat exchanger assemblies are connected in series with the compressor group.

6. The cascaded multi-stage compressor device for thermal mass energy storage according to claim 5, characterized in that: The heat exchanger assembly includes at least one heat exchanger, and the heat exchanger is connected in series between two adjacent compressors.

7. The multi-stage compressor device in series for thermal mass energy storage according to any one of claims 1 to 4, characterized in that: The rotating shafts of the multiple compressors in the same compressor group are connected in series in sequence, and the rotating shaft of the driving machine is connected to the rotating shaft of the compressor at the head end.

8. The multi-stage compressor device in series for thermal mass energy storage according to any one of claims 1 to 4, characterized in that: The pressure relief valve is arranged near the outlet of the corresponding terminal compressor.

9. A method for using a series-connected multi-stage compressor device for thermal mass energy storage, the method for using is based on the series-connected multi-stage compressor device for thermal mass energy storage according to any one of claims 1 to 8, characterized in that: include: Starting method: fully open the pressure relief valve and regulating valve of each compressor group, start the driving machine of the first compressor group, and gradually reduce the opening of the pressure relief valve of the first compressor group, the outlet pressure of the first compressor group gradually increases, and start to supply air to the second compressor group; After the inlet pressure of the second group of compressors reaches the starting pressure, the driving machine of the second group of compressors is started, and the opening of the pressure relief valve and the regulating valve of the second group of compressors is gradually reduced, the outlet pressure of the second group of compressors is gradually increased, and gas supply to the third group of compressors is started; then the remaining compressors are started in sequence according to the above method, and the pressure ratio is established from the first group of compressors to the last group of compressors. After the pressure relief valve and the regulating valve of the last group of compressors are closed, the last group of compressors enters a stable gas supply state to the subsequent process equipment, and the starting process is completed; Shutdown method: in the order from the last group of the compressor groups to the first group of the compressor groups, open the opening of the pressure relief valve of each group of the compressor groups to the fully open state; gradually open the opening of the regulating valve of each group of the compressor groups to the fully open state to avoid surge caused by insufficient intake flow of the corresponding compressor groups; in the order from the last group of the compressor groups to the first group of the compressor groups, close the driving machine of each group of the compressor groups, and each group of the compressor groups enters the inertial idling state; after the inertial idling of each group of the compressor groups is completed, close the pressure relief valve and regulating valve of each group of the compressor groups, and the shutdown process is completed.

10. The method for using the series-connected multi-stage compressor device for thermal mass energy storage according to claim 9, characterized in that: Also includes: Emergency shutdown method: When abnormal factors cause the driving motor of at least one group of the compressor groups to stop driving, immediately cut off the power source of all driving motors, and at the same time, open the opening of the pressure relief valve of each group of the compressor groups to a fully open state; gradually open the opening of the regulating valve of each group of the compressor groups to a fully open state to avoid surge caused by insufficient intake flow of the corresponding compressor group; after the inertial idling of each group of the compressor groups is completed, close the pressure relief valve and regulating valve of each group of the compressor groups, and the emergency shutdown process is completed.

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