Energy-saving multi-stage compressor system and energy-saving method thereof

Abstract

The invention belongs to the field of compressors, and discloses an energy-saving multi-stage compressor system and an energy saving method thereof.The energy-saving multi-stage compressor system comprises a multi-stage compressor unit and a steam turbine, the multi-stage compressor unit comprises a plurality of compression stages which are sequentially connected in series, and at least two adjacent compression stages are connected with a heat-electricity-cold self-coupling composite interstage cooler through a pipeline in a matched mode; the heat-electricity-cold self-coupling composite interstage cooler comprises a heat-electricity conversion module, a water cooling module and an electricity-cold conversion module which are sequentially connected from the previous compression stage to the next compression stage. The heat-electricity conversion module in the heat-electricity-cold self-coupling composite interstage cooler outputs direct current by utilizing heat of gas discharged from an outlet of a previous compression stage, the temperature of the gas is reduced, the gas is continuously cooled by utilizing circulating cooling water, the direct current output by the heat-electricity conversion module is directly supplied to the electricity-cold conversion module, and the heat-electricity conversion module is directly supplied to the electricity-cold conversion module. And the gas is further cooled through low-temperature cooling, the temperature of the gas entering the next compression stage is reduced, and the isothermal compression efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of compressors, and in particular to an energy-saving multi-stage compressor system and an energy-saving method thereof. Background Art

[0002] In various industries of the national economy such as metallurgy, petrochemicals, and medicine, due to the need for gas pressure in chemical synthesis / polymerization, gas transportation, refrigeration, gas separation, and the use of compressed air as a power source, it is necessary to compress and increase the pressure of air, coal gas, synthesis gas, gas-phase refrigerants, hydrogen, etc. The temperature of the gas continues to rise during the compression process in the compressor. Different compressed gases have different adiabatic indexes, and the temperature rise values ​​are different under the same pressure increase. However, the temperature rise amplitude of various gases during the compression process is related to the pressure ratio. The larger the pressure ratio, the higher the temperature rise. As the temperature of the gas in the compressor is higher, the compressor efficiency is lower, which increases the power consumption of the compressor unit. Therefore, in the gas compression demand required by the high pressure ratio, in order to reduce the average temperature of the gas in the compressor, improve the compression efficiency and reduce the energy consumption of the compressor unit, the compressor unit is generally designed as a multi-stage compression, and an intermediate cooler is set between each compression stage. The circulating cooling water is used to cool the high-temperature gas discharged from the previous compression stage, reduce the temperature of the gas entering the next compression stage, and reduce the power consumption of the unit.

[0003] The commonly used interstage coolers currently use circulating cooling water to indirectly cool the gas, which has the following problems: the circulating cooling water temperature is affected by the ambient temperature, and indirect heat transfer requires a certain temperature difference. The traditional interstage cooler has certain limitations on the temperature that can be reached for cooling high-temperature gas. The gas temperature out of the cooler is generally designed to be 40°C, which will result in poor cooling effect on the high-temperature gas, especially when the circulating cooling water temperature is relatively high in the hot summer season, resulting in low operating efficiency of the compressor unit. In extreme ambient temperature conditions, the compressor outlet temperature may be too high, causing the unit to alarm or even jump.

[0004] Because a certain temperature difference is required in the heat transfer process, the temperature to which the gas can be cooled is directly related to the temperature of the cold source in contact with the gas. Traditional circulating cooling water interstage coolers cannot achieve a lower cooling temperature.

[0005] In view of the problems existing in the multi-stage compressor system level using the circulating water cooling intercooler in the traditional configuration, for energy saving and safety considerations, being able to cool the gas to a lower temperature is an issue that needs to be urgently resolved in large multi-stage compressor systems. Summary of the invention

[0006] The object of the present invention is to provide an energy-saving multi-stage compressor system and an energy-saving method thereof to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions: An energy-saving multi-stage compressor system, comprising a multi-stage compressor unit and a steam turbine driving the multi-stage compressor unit, wherein the multi-stage compressor unit comprises a plurality of compression stages connected in series, and at least two adjacent compression stages are connected to a heat-electricity-cold self-coupling composite interstage cooler through a pipeline, wherein the heat-electricity-cold self-coupling composite interstage cooler comprises a heat-electricity conversion module, a water cooling module and an electric-cold conversion module connected in sequence from a previous compression stage to a next compression stage; The heat-to-electric conversion module utilizes the Seebeck effect of semiconductor materials to convert the thermal energy of the gas into electrical energy, transmits it to the electric-to-cold conversion module, and performs a primary cooling of the gas; The water cooling module performs secondary cooling on the gas; The electric-cold conversion module receives the electric energy transmitted by the heat-electric conversion module and uses the Peltier effect of semiconductor materials to cool the gas three times.

[0008] Furthermore, the heat-to-electric conversion module includes a first metal gas channel, a semiconductor thermoelectric power generation layer arranged outside the first metal gas channel, and a first water cooling jacket arranged outside the semiconductor thermoelectric power generation layer. The first metal gas channel is for gas to pass through. The semiconductor thermoelectric power generation layer includes a plurality of semiconductor thermoelectric generators. The semiconductor thermoelectric generators utilize the Seebeck effect of semiconductor materials to convert the thermal energy of the gas into electrical energy and transmit it to the electric-to-cold conversion module. The first water cooling jacket cools the cold side of the semiconductor thermoelectric power generation layer by cooling water.

[0009] Furthermore, a first enhanced heat transfer fin is provided on the inner wall of the first metal gas channel.

[0010] Furthermore, the water cooling module includes a second metal gas channel and a second water cooling jacket arranged outside the second metal gas channel, the second metal gas channel is for gas to pass through, and the second water cooling jacket cools the gas by cooling water.

[0011] Furthermore, a second enhanced heat transfer fin is disposed on the inner wall of the second metal gas channel.

[0012] Furthermore, the electric-cold conversion module includes a third metal gas channel, a semiconductor refrigeration layer arranged outside the third metal gas channel, and a third water cooling jacket arranged outside the semiconductor refrigeration layer. The third metal gas channel is for gas to pass through. The semiconductor refrigeration layer includes a plurality of semiconductor refrigerators. The semiconductor refrigerators receive electrical energy transmitted by the heat-electric conversion module and use the Peltier effect of semiconductor materials to cool the gas three times. The third water cooling jacket cools the hot side of the semiconductor refrigeration layer by cooling water.

[0013] Furthermore, a third enhanced heat transfer fin is arranged on the inner wall of the third metal gas channel.

[0014] Furthermore, all adjacent compression stages are connected to heat-electricity-cold self-coupling composite interstage coolers through pipelines.

[0015] The present invention provides an energy-saving method for the energy-saving multi-stage compressor system as described above, comprising: Step 1: The heat-to-electric conversion module uses the Seebeck effect of semiconductor materials to convert the heat energy of the exhaust gas from the previous compression stage outlet into electrical energy and transmits it to the electric-to-cold conversion module, and performs initial cooling of the gas; Step 2: The water cooling module performs secondary cooling on the gas; Step 3, the electric-cold conversion module receives the electric energy transmitted by the heat-electric conversion module, uses the Peltier effect of semiconductor materials to cool the gas three times, and transmits the gas after the three coolings to the next compression stage.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention utilizes the heat-to-electric conversion module in the heat-to-electric-cold self-coupling composite interstage cooler to utilize the heat of the exhaust gas at the outlet of the previous compression stage to output direct current, thereby reducing the gas temperature, and utilizes circulating cooling water to continue to cool the gas. The direct current output by the heat-to-electric conversion module is directly supplied to the electric-to-cold conversion module, and the gas is further cooled by low-temperature cooling, thereby reducing the gas temperature entering the next compression stage, improving the isothermal compression efficiency, reducing the energy consumption of the compressor system, and achieving the purpose of energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of an energy-saving multi-stage compressor system of the present invention.

[0018] Figure 2 The present invention is a schematic structural diagram of a heat-electricity-cold self-coupling composite interstage cooler in an energy-saving multi-stage compressor system.

[0019] Figure 3 This is a schematic diagram of the internal structure of a heat-to-electricity conversion module in an energy-saving multi-stage compressor system of the present invention.

[0020] Figure 4 It is a schematic diagram of the radial cross-section structure of a heat-to-electricity conversion module in an energy-saving multi-stage compressor system of the present invention.

[0021] Figure 5 This is a schematic diagram of the internal structure of a water cooling module in an energy-saving multi-stage compressor system of the present invention.

[0022] Figure 6 The figure is a schematic diagram of the internal structure of an electric-cold conversion module in an energy-saving multi-stage compressor system of the present invention.

[0023] Figure 7 It is a schematic diagram of the radial cross-section structure of an electric-cold conversion module in an energy-saving multi-stage compressor system of the present invention.

[0024] Figure 8 This is a flow chart of an energy-saving method for an energy-saving multi-stage compressor system of the present invention.

[0025] In the figure: 1 is a steam turbine, 2 is a compression stage, 3 is a heat-electric-cold self-coupling composite interstage cooler, 30 is a heat-electric conversion module, 300 is a first metal gas channel, 301 is a semiconductor temperature difference generator, 302 is a first water cooling jacket, 303 is a first enhanced heat transfer fin, 31 is a water cooling module, 310 is a second metal gas channel, 311 is a second water cooling jacket, 312 is a second enhanced heat transfer fin, 32 is an electric-cold conversion module, 320 is a third metal gas channel, 321 is a semiconductor refrigerator, 322 is a third water cooling jacket, and 323 is a third enhanced heat transfer fin. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] See also Figure 1-Figure 7 , an energy-saving multi-stage compressor system, including a multi-stage compressor unit and a steam turbine 1 driving the multi-stage compressor unit, the multi-stage compressor unit including two compression stages 2 connected in series, the compression stage 2 is a compressor, and the two adjacent compression stages 2 are connected by a pipeline to a heat-electric-cold self-coupling composite interstage cooler 3, the heat-electric-cold self-coupling composite interstage cooler 3 is composed of three sections of heat exchange modules in series, including a heat-electric conversion module 30, a water cooling module 31 and an electric-cold conversion module 32 connected in sequence from the air inlet end to the air outlet end. The heat-electric conversion module 30 uses the Seebeck effect of semiconductor materials to convert the thermal energy of the gas into electrical energy and transmit it to the electric-cold conversion module 32, and performs the initial cooling of the gas. The water cooling module 31 performs the secondary cooling of the gas. The electric-cold conversion module 32 receives the electrical energy transmitted by the heat-electric conversion module 30, and uses the Peltier effect of semiconductor materials to perform the tertiary cooling of the gas.

[0028] It should be noted that the multi-stage compressor unit may also include three or even more compression stages 2, and any two adjacent compression stages 2 may be connected to a heat-electricity-cold self-coupling composite interstage cooler 3 via a pipeline.

[0029] Continue reading Figure 3 and Figure 4 In one embodiment of the present invention, the heat-to-electric conversion module 30 includes a first metal gas channel 300, a semiconductor thermoelectric power generation layer disposed outside the first metal gas channel 300, and a first water cooling jacket 302 disposed outside the semiconductor thermoelectric power generation layer. The first metal gas channel 300 is a circular cylindrical structure, and the first metal gas channel 300 is for gas to pass through, and has a gas inlet and a gas outlet. The inner wall of the first metal gas channel 300 is also provided with a plurality of first enhanced heat transfer fins 303. The semiconductor thermoelectric power generation layer is an annular structure surrounded on the outer wall of the first metal gas channel 300, and includes a plurality of uniformly distributed semiconductor thermoelectric generators 301, which are also called semiconductor thermoelectric power generation sheets, which utilize the Seebeck effect of semiconductor materials to convert the thermal energy of the gas into electrical energy and transmit it to the electric-to-cold conversion module 32, and the semiconductor thermoelectric power generation sheet includes a cold side and a hot side, the cold side is close to the first water cooling jacket 302, and the hot side is close to the first metal gas channel 300. The first water cooling jacket 302 is also an annular structure, which is arranged outside the semiconductor thermoelectric power generation layer, and cools the cold side of the semiconductor thermoelectric power generation layer by circulating cooling water. Among them, the output wires of a single semiconductor thermoelectric power generation sheet are connected in parallel or in series, so that multiple semiconductor thermoelectric power generation sheets are integrated into a semiconductor thermoelectric power generation stack to improve the output voltage, current and power.

[0030] The above-mentioned heat-electric conversion module 30 is set in the high-temperature gas section. The high-temperature gas inside the wall and the circulating cooling water on the outer wall form a temperature difference. The Seebeck effect of semiconductor materials is used to convert the internal high-temperature gas heat energy into electrical energy, which is output through the power generation stack lead wire and the gas temperature is reduced. In order to improve the power generation efficiency, the outlet temperature of this section is designed to be 80°C.

[0031] Continue reading Figure 5 In one embodiment of the present invention, the water cooling module 31 includes a second metal gas channel 310 and a second water cooling jacket 311 disposed outside the second metal gas channel 310. The second metal gas channel 310 is a circular cylindrical structure. The second metal gas channel 310 is for gas to pass through, and has a gas inlet and a gas outlet. The inner wall of the second metal gas channel 310 is also provided with a plurality of second enhanced heat transfer fins 312. The second water cooling jacket 311 is also an annular structure, which is disposed outside the second metal gas channel 310, and cools the gas by circulating cooling water.

[0032] The water cooling module 31 is disposed after the heat-electric conversion module 30, and uses the normal temperature circulating cooling water to further cool the gas to 40°C, which is also the temperature to which the general circulating cooling water can cool the gas.

[0033] Continue reading Figure 6 and Figure 7 In one embodiment of the present invention, the electric-cold conversion module 32 includes a third metal gas channel 320, a semiconductor refrigeration layer arranged outside the third metal gas channel 320, and a third water cooling jacket 322 arranged outside the semiconductor refrigeration layer. The third metal gas channel 320 is a circular cylindrical structure, and the third metal gas channel 320 is for gas to pass through, and has a gas inlet and a gas outlet. The inner wall of the third metal gas channel 320 is also provided with a plurality of third enhanced heat transfer fins 323. The semiconductor refrigeration layer is an annular structure surrounded on the outer wall of the third metal gas channel 320, and includes a plurality of uniformly distributed semiconductor refrigerators 321, which are also called semiconductor refrigeration sheets. The semiconductor refrigerator 321 receives the electric energy transmitted by the heat-electric conversion module 30, and uses the Peltier effect of the semiconductor material to cool the gas three times. The semiconductor refrigeration sheet includes a cold side and a hot side, and the cold side is close to the third metal gas channel 320, and the hot side is close to the third water cooling jacket 322. The third water cooling jacket 322 is also an annular structure, which is arranged outside the semiconductor refrigeration layer, and cools the cold side of the semiconductor temperature difference power generation layer by circulating cooling water. Among them, the input wires of a single semiconductor refrigeration piece are connected in parallel or series, so that multiple semiconductor refrigeration pieces are integrated into a semiconductor refrigeration stack to improve the cooling capacity and cooling efficiency.

[0034] The electric-cold conversion module 32 is arranged in the low-temperature section of the gas, that is, after the water cooling module 31. By introducing the electric energy output by the heat-electric conversion module 30, the Peltier effect of the semiconductor material is used to form a temperature difference of 60°C on both sides of the wall, that is, the temperature of the inner cold surface is 60°C lower than that of the outer hot surface. The outer side is cooled by circulating cooling water to maintain an average temperature of 35°C, and the temperature that can be achieved on the inner side is -25°C. The heat exchange with the gas is carried out through the inner enhanced heat transfer fins. On the basis of the temperature reduction range that can be achieved by the water cooling module 31, the gas is cooled again to reduce the gas temperature of the next compression stage and reduce the compression power consumption.

[0035] The three sections of the internal gas channels of the first metal gas channel 300, the second metal gas channel 310 and the third metal gas channel 320 are connected in series to form a closed channel, and each section of the external circulating cooling water jacket is independently provided.

[0036] Since the reduction of intake temperature of a single compression stage has a certain proportional relationship with the reduction of energy consumption of the compression stage, preferably, the electric-cold conversion module 32 is arranged at the front section of the compression stage where the single-stage compression power consumption is large, which is more conducive to reducing the energy consumption of the compressor system.

[0037] See also Figure 8 , an energy-saving method for the energy-saving multi-stage compressor system as described above, comprising the following steps: Step 1: The high-temperature gas outputted by the previous compression stage 2 enters the heat-to-electric conversion module 30 through the pipeline. The heat-to-electric conversion module 30 uses the Seebeck effect of semiconductor materials to convert the heat energy of the high-temperature gas into electrical energy and transmits it to the electric-to-cold conversion module 32, and performs the initial cooling of the high-temperature gas. The gas after the initial cooling enters the water cooling module.

[0038] Step 2: The water cooling module 31 performs secondary cooling on the gas, and the gas after secondary cooling enters the electric-cold conversion module 32.

[0039] Step 3, the electric-cold conversion module 32 receives the electric energy transmitted by the heat-electric conversion module 30, uses the Peltier effect of the semiconductor material to cool the gas three times, and transmits the gas after the three coolings to the next compression stage 2.

[0040] Example

[0041] 1. Gas compression requirements and traditional compressor system structure An air compressor with a compressed air volume of 225,000 Nm³ / h needs to compress the air pressure to 0.8 MPa(a). It is driven by a condensing steam turbine, which consumes 4.0 MPa(a) steam and 400°C superheated steam, and does 220 kW.h / t of work per ton of steam. In order to improve the compression efficiency, the compressor system is equipped with two compression stages, with a circulating water cooler in between. The traditional system parameter indicators are as follows:

[0042] 2. Design steps and methods of the present invention The heat-electricity-cold self-coupling composite interstage cooler 3 of the present invention is equipped between the first and second compression stages to cool the gas.

[0043] 1. Component matching 1. According to the temperature of 80℃ of the first stage heat-electric conversion module 30 of the gas inter-stage cooler, the heat released by the gas is 10461kW. According to the technical indicators of the semiconductor thermoelectric power generation chip produced by Shenzhen Dahuineng Technology Co., Ltd. (model: TEG-10-6230, matching voltage: 4.2V, matching current: 7.3A, output power 30.6W, thermoelectric conversion efficiency: 5.1%), 17,500 single components are required; 2. According to the design of output voltage 110V, the single components are connected in series and parallel. The power generation stack consists of 100 pieces in each group with positive and negative poles connected in series. The output voltage of a single string is 420V and the current is 7.3A. There are 175 strings in total. After the positive and negative poles of the 175 strings are connected in parallel, a power generation stack is formed. The total voltage is 420V, the total current is 1277.5A, and the total output power is 536kW. 3. The input electric energy of the third-stage electric-cold conversion module 32 of the interstage cooler is the electric energy output by the first-stage heat-electric conversion module 30, that is, 536kW. According to the technical indicators of the semiconductor refrigeration sheet produced by Anhui Fuxin Semiconductor Technology Co., Ltd. (model: TEC1-12715, rated voltage: 12V, rated current: 15A, input power 180W, cooling power 150W, cooling efficiency 83.3%, temperature difference between hot and cold surfaces 60°C), 2975 single components are required, with a total cooling capacity of 446kW. Each group of 35 pieces is used for positive and negative poles to be connected in series, for a total of 85 strings. The positive and negative poles of the 85 strings are connected in parallel at the beginning and end to form a cooling stack. The total voltage and current match the output parameters of the first-stage heat-electric conversion module 30.

[0044] (II) Interstage cooler design method 1. The first stage heat-electric conversion heat exchange module Based on the inlet temperature of 208℃, the outlet temperature of 80℃, the gas heat transfer coefficient, the gas channel flow rate and other factors, the inner side enhanced heat transfer structure and area are calculated according to the heat exchanger design specifications.

[0045] 2. The second stage water-cooled heat exchange module Based on the inlet air temperature of 80℃, outlet air temperature of 40℃ and the inlet temperature of circulating cooling water, calculate the internal enhanced heat transfer structure and area according to the heat exchanger design specifications; 3. The third section of electric-cold conversion heat exchange module According to the total cooling capacity, the gas temperature of the third section module is calculated to be 34.5°C. The inner enhanced heat transfer structure and area are calculated based on the inlet temperature of 40°C, the outlet temperature of 34.5°C and the cold side wall temperature of -25°C.

[0046] 3. Equipment integrated manufacturing The cooler is manufactured according to the matching results of components and the design results of the interstage cooler cylinder structure. After the overall assembly, it is connected between the outlet and inlet of the two compression stages of the compressor.

[0047] 3. Energy-saving effect of operation By utilizing the technical solution of the present invention, the inlet temperature of the second compression stage is lowered, and the power consumption of the second compression stage is reduced from 9464kW to 9297kW. The power consumption of the overall compression system is reduced by 167kW. Based on the working capacity of the steam turbine of 220kW.h / t, 0.76t / h of steam is saved per hour. Based on the steam price of 250 yuan / t and 8400h of annual operation, the system saves 1.6416 million yuan in steam cost per year. Based on the use of the compressor for 30 years, a cumulative saving of 49.248 million yuan is achieved, and the cost saved is much higher than the equipment procurement cost.

[0048] 4. Other preferred embodiments of the present invention According to the preferred solution of the present invention, the inlet temperature of the compression stage with high energy consumption is preferentially reduced, so that a better energy-saving effect can be achieved. In the embodiment of the present invention, since the energy consumption of the first compression stage is 15277kW, which is greater than the energy consumption of the second compression stage, 9464kW, the electric-cold conversion module is arranged at the inlet end of the first compression stage to reduce the inlet temperature of the first compression stage, so that the power consumption of the first compression stage can be reduced from 15277kW to 14992kW, and the steam compression system reduces the power consumption by 285kW, which is 1.7 times the above-mentioned benefit.

[0049] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An energy-saving multi-stage compressor system, comprising a multi-stage compressor unit and a steam turbine (1) for driving the multi-stage compressor unit, wherein the multi-stage compressor unit comprises a plurality of compression stages (2) connected in series, characterized in that: A heat-electricity-cold self-coupling composite interstage cooler (3) is connected between at least two adjacent compression stages (2) via pipelines, wherein the heat-electricity-cold self-coupling composite interstage cooler (3) comprises a heat-electricity conversion module (30), a water cooling module (31), and an electricity-cold conversion module (32) which are sequentially connected from the previous compression stage to the next compression stage; The heat-to-electricity conversion module (30) utilizes the Seebeck effect of semiconductor materials to convert the thermal energy of the gas into electrical energy, transmits it to the electricity-to-cold conversion module (32), and performs a primary cooling of the gas; The water cooling module (31) performs secondary cooling on the gas; The electric-cold conversion module (32) receives the electric energy transmitted by the heat-electric conversion module (30) and uses the Peltier effect of semiconductor materials to cool the gas three times.

2. An energy-saving multi-stage compressor system according to claim 1, characterized in that: The heat-to-electric conversion module (30) comprises a first metal gas channel (300), a semiconductor temperature difference power generation layer arranged outside the first metal gas channel (300), and a first water cooling jacket (302) arranged outside the semiconductor temperature difference power generation layer. The first metal gas channel (300) allows gas to pass through. The semiconductor temperature difference power generation layer comprises a plurality of semiconductor temperature difference generators (301). The semiconductor temperature difference generators (301) utilize the Seebeck effect of semiconductor materials to convert the thermal energy of the gas into electrical energy and transmit it to the electricity-to-cold conversion module (32). The first water cooling jacket (302) uses cooling water to cool the cold side of the semiconductor temperature difference power generation layer.

3. An energy-saving multi-stage compressor system according to claim 2, characterized in that: A first enhanced heat transfer fin (303) is provided on the inner wall of the first metal gas channel (300).

4. The energy-saving multi-stage compressor system according to claim 1, characterized in that: The water cooling module (31) comprises a second metal gas channel (310) and a second water cooling jacket (311) arranged outside the second metal gas channel (310); the second metal gas channel (310) allows gas to pass through; and the second water cooling jacket (311) cools the gas by cooling water.

5. An energy-saving multi-stage compressor system according to claim 4, characterized in that: Second enhanced heat transfer fins (312) are provided on the inner wall of the second metal gas channel (310).

6. The energy-saving multi-stage compressor system according to claim 1, characterized in that: The electric-cold conversion module (32) comprises a third metal gas channel (320), a semiconductor refrigeration layer arranged outside the third metal gas channel (320), and a third water cooling jacket (322) arranged outside the semiconductor refrigeration layer. The third metal gas channel (320) allows gas to pass through. The semiconductor refrigeration layer comprises a plurality of semiconductor refrigerators (321). The semiconductor refrigerators (321) receive electric energy transmitted by the heat-electric conversion module (30) and use the Peltier effect of semiconductor materials to cool the gas three times. The third water cooling jacket (322) cools the hot side of the semiconductor refrigeration layer by cooling water.

7. An energy-saving multi-stage compressor system according to claim 6, characterized in that: The inner wall of the third metal gas channel (320) is provided with a third enhanced heat transfer fin (323).

8. The energy-saving multi-stage compressor system according to claim 1, characterized in that: All adjacent compression stages (2) are connected to a heat-electricity-cold self-coupling composite interstage cooler (3) via pipelines.

9. An energy-saving method for an energy-saving multi-stage compressor system as claimed in any one of claims 1 to 8, characterized in that: include: Step 1, the heat-to-electric conversion module (30) utilizes the Seebeck effect of semiconductor materials to convert the heat energy of the exhaust gas at the outlet of the previous compression stage (2) into electrical energy and transmits it to the electric-to-cold conversion module (32), thereby performing a primary cooling of the gas; Step 2, the water cooling module (31) performs secondary cooling on the gas; Step 3: The electric-cold conversion module (32) receives the electric energy transmitted by the heat-electric conversion module (30), uses the Peltier effect of the semiconductor material to cool the gas three times, and transmits the gas after the three coolings to the next compression stage (2).

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