Isothermal isobaric gas engine

Abstract

An isothermal and isobaric gas engine comprises an isothermal compression system, an isothermal expansion system, a countercurrent heat exchanger, a control device, a circulating working medium and connecting pipelines among the isothermal compression system, the isothermal expansion system, the countercurrent heat exchanger, the control device and the circulating working medium. A working medium inlet of the isothermal compression system is directly connected with air, a working medium outlet of the isothermal compression system is communicated with one end of a working medium channel of the countercurrent heat exchanger, and the other end of the working medium channel of the countercurrent heat exchanger is communicated with a working medium inlet of the isothermal expansion system; a tail gas outlet of the isothermal expansion system communicates with a tail gas channel inlet of the countercurrent heat exchanger, and a tail gas channel outlet of the countercurrent heat exchanger communicates with air. According to the design, the efficiency of the gas engine is improved through the multi-stage compression, multi-stage expansion and the isobaric countercurrent flow heat exchange process.

Description

Technical Field

[0001] The utility model belongs to the technical field of energy storage, and particularly relates to an isothermal and isobaric gas engine. Background Technique

[0002] At present, a series of challenges are faced in the design and manufacture of gas engines. One of the key limiting factors is the performance of materials at high temperatures. Since gas engines generate extremely high temperatures during the compression and combustion processes, these high-temperature environments pose extremely high requirements for the heat resistance and mechanical properties of engine materials. Isothermal compression and isothermal expansion technologies are a potential way to solve the high-temperature problems of gas engines. These two technologies can keep the gas temperature constant during the compression or expansion process, thereby reducing energy loss and improving engine efficiency.

[0003] The existing patented technology "Isothermal Compression and Expansion Open Air Cycle Engine and Power Generation System" (Patent Application Publication No.: CN116291788A) is an open air cycle engine device with approximately isothermal compression and isothermal expansion of the working medium. The working medium (air) during the air compression process is cooled multiple times, so that the compression mechanism always maintains a relatively low working temperature; during the expansion process, the thermal energy of solar thermal energy is used for multi-stage heating and expansion, approaching isothermal expansion, and the efficiency of the entire device is significantly improved; however, the working temperature of the entire device belongs to the medium and low temperature range, and high-efficiency power generation can only be achieved by relying on solar energy. In case of rainy weather, the power generation efficiency of the entire system is relatively low. The utility model is an improvement and expansion of the patented technology "Isothermal Compression and Expansion Open Air Cycle Engine and Power Generation System". Multiple combustions are directly carried out during isothermal expansion to achieve high-temperature full combustion. At the same time, the waste heat of the exhaust gas during isothermal expansion is recovered through the design of a countercurrent heat exchanger, improving the thermal efficiency of the engine; the utility model supplements the engine system in the high-temperature working area of the existing patent, and at the same time does not rely on solar energy during the power generation process, achieves waste heat recovery of the exhaust gas, and can always provide high-efficiency and stable power supply. Summary of the Invention

[0004] The utility model provides an isothermal and isobaric gas engine, which combines three technologies: isothermal compression, isothermal expansion, and isobaric countercurrent heat exchange, realizes the organic combination of compressed air power generation and gas, and can also be used as a backup energy source, forming a brand-new energy supply mode.

[0005] Specifically described as follows: An isothermal and isobaric gas engine includes an isothermal compression system, an isothermal expansion system, a countercurrent heat exchanger, a control device, a circulating working medium, and the connecting pipes between them;

[0006] The isothermal compression system includes an isothermal compressor, a cooler, and a compressed working fluid pipeline between them; the isothermal compressor is a multi-stage isothermal compressor; the cooler is a multi-stage cooler, and the cooler is installed on the compressed working fluid pipeline between every two stages of the isothermal compressor;

[0007] The isothermal expansion system includes an isothermal expander, a combustion chamber, and a compressed working fluid pipeline; the isothermal expander is a multi-stage isothermal expander; the combustion chamber is a multi-stage combustion chamber, which is installed on the expanded working fluid pipeline between every two stages of the isothermal expander or on the working fluid pipeline between the countercurrent heat exchanger and the first-stage isothermal expander;

[0008] The working fluid inlet of the first-stage isothermal compressor of the isothermal compressor is directly connected to the environment, the working fluid outlet of the last-stage isothermal compressor is communicated with the inlet of the working fluid channel of the countercurrent heat exchanger, and the outlet of the working fluid channel of the countercurrent heat exchanger is communicated with the working fluid inlet of the first-stage combustion chamber of the isothermal expansion system; the exhaust gas outlet of the last-stage isothermal expander of the isothermal expansion system is communicated with the inlet of the exhaust gas channel of the countercurrent heat exchanger, and the outlet of the exhaust gas channel of the countercurrent heat exchanger is communicated with the air.

[0009] Further, the cooler is a water cooling tower or an air-cooled cooler, and the inlet / outlet of the air medium channel of the cooler is respectively connected to the working fluid outlet of the upper-stage isothermal compressor / the working fluid inlet of the lower-stage isothermal compressor.

[0010] Further, the isothermal compressor is of centrifugal or axial-flow type and is composed of a multi-stage isothermal compressor connected in series coaxially.

[0011] Further, the isothermal expander is of turbine type and is composed of a multi-stage expander connected in series coaxially.

[0012] Further, the fuel in the combustion chamber is coal gas, natural gas, hydrogen, or liquid fuel.

[0013] As described above for the gas engine, since the isothermal compressor is divided into multiple stages, and the temperature rise during each stage of compression is limited to a small temperature difference value, and in addition, after each compression, the cooler is used to lower the temperature of the compressed working fluid, this approximately realizes the process of "isothermal compression"; by using a similar method, an approximately "isothermal expansion" process of the working fluid during the expansion process is realized. This makes the entire thermodynamic process closer to the "Carnot cycle" process, and therefore, a relatively high system thermal efficiency can be obtained.

[0014] By adopting the method of multi-stage expansion accompanied by multi-stage heating, compared with single-stage expansion or a few-stage expansion processes, the working fluid can maintain a relatively high temperature and a relatively high average temperature throughout the expansion process. According to the Carnot cycle principle, the higher this temperature, the higher the efficiency of the thermal system. Similarly, through multi-stage compression and heat dissipation cooling, the compression process is maintained at a relatively low temperature to achieve approximate "isothermal compression", which also improves the efficiency of the thermal system. By comparing the maximum efficiency of the theoretical cycle, the potential for efficiency improvement of the present invention can be understood.

[0015] By designing a countercurrent heat exchanger to recover the heat of the high-temperature exhaust gas finally discharged from the isothermal expansion and using it for the isobaric preheating of compressed air, the energy utilization rate can be significantly improved.

[0016] The present invention plays a crucial role in the field of new energy power generation, especially in photovoltaic and wind power generation. It can not only significantly alleviate the volatility and intermittency of new energy, reduce the impact on the power grid, and reduce the phenomena of "light abandonment and wind abandonment", but also greatly improve the stability and reliability of the power grid operation.

[0017] In addition, a remarkable feature of this engine is that it directly uses air as the working fluid and adopts an open-cycle design. This design makes the impact on the system efficiency relatively small even if there is a slight leakage during the working process. This not only reduces the strict requirements for the manufacturing and assembly accuracy of components, but also further reduces the equipment cost and the later maintenance cost, making the present invention more attractive in terms of economy.

[0018] It is worth mentioning that the working principle of this engine is similar to that of a gas turbine, so it also has the ability to start and stop quickly. This characteristic greatly improves the flexibility and adaptability of the system, enabling it to quickly respond to various demand changes of the power grid. Generally speaking, the gas engine described in the present invention shows significant advantages in terms of efficiency, stability, flexibility, and economy. Compared with traditional gas engines and the existing technology, it undoubtedly has higher efficiency and a broader application prospect. Brief Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Attached Figure 1 is a schematic diagram of the structure and principle of the gas engine of the present invention.

[0021] The meanings represented by the serial numbers in the above figures are as follows: 1 isothermal compressor; 11 primary isothermal compressor; 12 secondary isothermal compressor; 1m final-stage isothermal compressor; 2 cooler; 21 primary cooler; 22 secondary cooler; 2m-1 final-stage cooler; 3 countercurrent heat exchanger; 4 control device; 5 combustion chamber; 51 primary combustion chamber; 52 secondary combustion chamber; 5n final-stage combustion chamber; 6 isothermal expander; 61 primary isothermal expander; 62 secondary isothermal expander; 6n final-stage isothermal expander. Specific implementation manners

[0022] To make the objectives, technical solutions and advantages of the present utility model clearer, the technical solutions of the present utility model will be described in detail below.

[0023] Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments.

[0024] All other implementation manners obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts fall within the scope protected by the present utility model. To make the embodiments easier to understand, multiple embodiments or implementation methods are provided below to illustrate the related devices, modules, and functions of the present utility model.

[0025] To enable the readers of this embodiment to quickly understand the implementation manner of the present utility model, the working principle expressed here will be described first for the attached Figure 1 figure.

[0026] As shown in the attached Figure 1 figure, an isothermal and isobaric gas engine includes: an isothermal compression system, an isothermal expansion system, a countercurrent heat exchanger 3, a control device 4, a circulating working medium, and the connecting pipes between them. The working medium inlet of the isothermal compression system is directly connected to the environment, the working medium outlet of the isothermal compression system is communicated with the working medium channel inlet of the countercurrent heat exchanger 3, and the outlet of the working medium channel of the countercurrent heat exchanger 3 is communicated with the working medium inlet of the isothermal expansion system; the exhaust gas outlet of the isothermal expansion system is communicated with the exhaust gas channel of the countercurrent heat exchanger 3, and the countercurrent heat exchanger 3 recovers the heat of the exhaust gas after expansion work to preheat the compressed air before doing work; the final exhaust gas is directly discharged into the environment after the countercurrent heat exchanger 3 recovers the heat.

[0027] The isothermal compression system includes an isothermal compressor 1, a cooler 2, and the compressed working medium pipeline between them; the function of the isothermal compressor 1 is to inhale the working medium air and perform multi-stage isothermal compression on the working medium air to increase the pressure of the working medium. The isothermal compressor 1 is a multi-stage isothermal compressor, including m-stage compressors 11 to 1m (m≥2); the working medium inlet of the primary isothermal compressor 11 is directly connected to the environment, and the outlet of the final-stage isothermal compressor 1m is communicated with the working medium channel inlet of the countercurrent heat exchanger 3.

[0028] The cooler 2 is installed on the compressed working medium pipeline between every two - stage isothermal compressors, and includes 2m - 1 coolers; the inlet / outlet of the working medium channel of the cooler 2 is respectively connected to the working medium outlet of the previous - stage isothermal compressor / the working medium inlet of the next - stage isothermal compressor; the function of the cooler 2 is to dissipate the heat generated by the isothermal compressor 1 to the outside, so that the compression process is maintained at a lower temperature, realizing approximate "isothermal compression".

[0029] The isothermal expansion system includes an isothermal expander 6, a combustion chamber 5, and a compressed working medium pipeline; the isothermal expander 6 includes n - stage isothermal expanders (n≥2); the combustion chamber 5 includes a plurality of combustion chambers equal in number to the isothermal expanders, and the combustion chamber 5 is installed on the expanded working medium pipeline between every two - stage isothermal expanders or on the working medium pipeline between the counter - current heat exchanger 3 and the first - stage isothermal expander 61, that is, the first - stage combustion chamber 51 is installed on the working medium pipeline between the working medium channel of the counter - current heat exchanger 3 and the first - stage isothermal expander 61, and the inlets / outlets of the combustion chambers 52~5n are respectively connected to the working medium outlet of the previous - stage isothermal expander / the working medium inlet of the next - stage isothermal expander; the working medium outlet of the last - stage isothermal expander 6n is connected to the tail - gas inlet of the counter - current heat exchanger 3.

[0030] Each stage of the isothermal compressors 11~1m and each stage of the isothermal expanders 61~6n are coaxially connected in series.

[0031] The inlet of the working medium channel of the counter - current heat exchanger 3 is communicated with the outlet of the last - stage isothermal compressor 1m; the outlet of the working medium channel of the counter - current heat exchanger 3 is communicated with the working medium inlet of the primary combustion chamber 51; the tail - gas outlet of the last - stage isothermal expander 6n is communicated with the inlet of the tail - gas channel of the counter - current heat exchanger 3, and the outlet of the tail - gas channel of the counter - current heat exchanger 3 is directly communicated with the environment; the function of the counter - current heat exchanger 3 is to recover the heat after isothermal expansion for pre - heating before the compressed air does work; that is, the compressed air discharged from the last - stage compressor 1m exchanges heat with the tail gas discharged from the last - stage isothermal expander 6n in the counter - current heat exchanger 3, and the compressed air absorbs the heat of the tail gas to achieve pre - heating, and then enters the primary combustion chamber 51.

[0032] The combustion chamber 5 is injected with fuel gas and mixed with the compressed air of the circulating working medium entering the combustion chamber and burns fully to generate tail gas. The isothermal expander 6 is connected to the combustion chamber and is driven by the tail gas generated by the combustion chamber 5 to generate power for electricity generation.

[0033] The fuel in the combustion chamber 5 is coal gas, natural gas, hydrogen, liquid fuel, etc.

[0034] If the cooler 2 is a water - cooled cooler, the inlets / outlets of the cooling medium channels of the cooler 2 are respectively connected to the outlets / inlets of the cold - water water source; if the cooler 2 is an air - cooled cooler, the inlets / outlets of the cooling medium channels of the cooler 2 are both connected to the air.

[0035] The circulating working fluid is air.

[0036] The working cycle process of the gas engine of the present utility model is as follows: The primary isothermal compressor 11 sucks in the working fluid air from the environment for compression, and both the temperature and pressure of the working fluid air rise; to avoid too much increase in the working fluid temperature, after the primary pressurization by the primary isothermal compressor 11, the working fluid air directly enters the primary cooler 21 for temperature reduction, and after the temperature reduction, the once-pressurized working fluid air enters the secondary isothermal compressor 12 for secondary pressurization, and then enters the secondary cooler 22 for temperature reduction, and so on until it is compressed to a predetermined pressure in the final-stage isothermal compressor 1m, and then directly enters the countercurrent heat exchanger 3 to exchange heat with the high-temperature final exhaust gas discharged from the final-stage isothermal expander 6n. The compressed air is preheated by the high-temperature final exhaust gas to become high-pressure medium-temperature compressed air, and then enters the primary combustion chamber 51. At the same time, the primary combustion chamber 51 is injected with fuel and mixed with the working fluid compressed air entering the combustion chamber and then burns fully to generate the primary exhaust gas; the isothermal primary expander 61 is connected to the primary combustion chamber 51, and the isothermal primary expander 61 is driven by the incoming primary exhaust gas and generates power and work, and then the temperature and pressure of the primary exhaust gas are reduced; the temperature-reduced and pressure-reduced primary exhaust gas discharged from the isothermal primary expander 61 enters the secondary combustion chamber 52, is mixed with the injected fuel and burns fully again to generate the secondary exhaust gas, and then the secondary exhaust gas enters the isothermal secondary expander 62, and the isothermal secondary expander 62 is driven and generates power and work, and then the temperature and pressure of the secondary exhaust gas are reduced; in this way, the exhaust gas reaches the final combustion chamber 5n and is mixed with the coal gas for final combustion to generate the final exhaust gas, and the final exhaust gas drives the final expander 6n to generate power for power generation. The final exhaust gas discharged from the final expander 6n is not directly discharged into the air, but directly enters the countercurrent heat exchanger 3 for heat recovery, and the final exhaust gas discharged from the countercurrent heat exchanger 3 has a temperature close to the ambient temperature and is directly discharged into the environment. Such a cyclic operation completes the entire cycle process.

[0037] As described above, the main purpose of adopting multi-stage compression is to avoid too high a temperature rise during the compression process because we want to achieve "approximate" isothermal compression. The entire compression process is completed by the isothermal compressor 1.

[0038] To achieve approximate isothermal compression, the cooler 2 is used to dissipate the compression heat of each stage of the isothermal compression mechanism to the external air; for this purpose, a cooler 2 is installed between every two stages of the isothermal compression mechanism to promptly dissipate the compression heat.

[0039] As described above, the main purpose of adopting multi-stage isothermal expansion is as follows: through multi-stage isothermal expansion, the pressure of the working fluid is gradually reduced to avoid large temperature differences and low efficiency during the expansion process, because we need to achieve "approximate" isothermal expansion. The entire expansion process is completed by the isothermal expander 6. To achieve approximate isothermal expansion, the working fluid air before entering the isothermal expander 6 first enters the combustion chamber 5 and mixes with the fuel for full combustion to generate exhaust gas with a constant temperature, which drives each stage of the isothermal expander to do work.

[0040] To further improve the embodiment of the present invention, a control scheme for the gas engine in this embodiment is provided here, that is: a set of control device 4 is provided for the gas engine. A relatively preferred control device is the DCS system. Using this DCS system, the various components of the gas engine can be comprehensively controlled hierarchically and the mutual influence between the controller devices can be reduced. The DCS control system collects the working parameters of each component of the engine equipment, including but not limited to temperature, pressure, flow rate, stress, displacement, vibration, position, current, voltage, resistance, frequency, power, and comprehensively controls and protects the operation of each component.

Claims

1. An isothermal and isobaric gas engine, characterized in that: It includes isothermal compression system, isothermal expansion system, countercurrent heat exchanger, control device, circulating working fluid and connecting pipes between them; The isothermal compression system includes an isothermal compressor, a cooler, and a compressed working fluid pipeline therebetween; The isothermal compressor is a multi-stage isothermal compressor; the cooler has a multi-stage cooler; the cooler is installed on the compressed working medium pipeline between every two stages of the isothermal compressor; The isothermal expansion system comprises an isothermal expander, a combustion chamber and a compressed working medium pipeline; the isothermal expander is a multi-stage isothermal expander; the combustion chamber is a multi-stage combustion chamber, which is installed on the expansion working medium pipeline between every two stages of isothermal expanders or on the working medium pipeline between the countercurrent heat exchanger and the first stage isothermal expander; The working fluid inlet of the first-stage isothermal compressor of the isothermal compressor is directly connected to the air, the working fluid outlet of the last-stage isothermal compressor is connected to the working fluid channel inlet of the countercurrent heat exchanger, and the outlet of the working fluid channel of the countercurrent heat exchanger is connected to the working fluid inlet of the first-stage combustion chamber of the isothermal expansion system; the exhaust gas outlet of the last-stage isothermal expander of the isothermal expansion system is connected to the exhaust gas channel inlet of the countercurrent heat exchanger, and the exhaust gas channel outlet of the countercurrent heat exchanger is connected to the environment.

2. An isothermal and isobaric gas engine according to claim 1, characterized in that: The cooler is a water cooling tower or an air-cooled cooler, and the inlet / outlet of the working medium channel of the cooler is respectively connected to the working medium outlet of the previous stage isothermal compressor / the working medium inlet of the next stage isothermal compressor.

3. The isothermal and isobaric gas engine according to claim 1, characterized in that: The isothermal compressor is of centrifugal or axial flow type and is composed of multiple stages of isothermal compressors connected in series coaxially.

4. The isothermal and isobaric gas engine according to claim 1, characterized in that: The isothermal expander is of turbine type and is composed of multiple stages of expanders connected in series coaxially.

5. The isothermal and isobaric gas engine according to claim 1, characterized in that: The fuel in the combustion chamber is coal gas, natural gas, hydrogen or liquid fuel.

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