Liquid air and Stirling refrigeration and power generation two-way long-time energy storage machine

Abstract

Electric energy storage is a difficult problem. The patent is invented by a method, liquid air is used for storing energy, and a Stirling engine is used as a bidirectional energy conversion machine for refrigeration and power generation. Although the power generation efficiency of an existing Stirling engine is not higher than 40%, the refrigeration efficiency of the Stirling engine can reach up to 300%, the heat engine efficiency generally lower than 50% is perfectly compensated with the refrigeration efficiency larger than 100%, the overall power reduction rate can reach 60% or above, and a new and complete power energy storage technical scheme is formed. The two-way long-time energy storage machine (liquid air, Stirling refrigeration and power generation) can be widely arranged at a power generation end, a power utilization end and a power transmission end in a distributed and multi-point manner without being limited by geographical conditions; power generation fluctuation (especially photovoltaic and wind power generation fluctuation), power transmission fluctuation (especially guaranteeing stability of power transmission power) and power utilization fluctuation (especially balancing peak and valley of power utilization) can be balanced, and the problem of power storage of power peak and valley fluctuation can be widely solved.

Description

Technical Field

[0001] Power energy storage field. Background Art

[0002] Electric energy storage is a difficult problem. At present, the more mature electric energy storage is the pumped energy storage power station (the power reduction rate is generally not higher than 75%), and the more advanced one is the compressed air energy storage (the power reduction rate is generally not higher than 60%). These two energy storage methods are subject to the prerequisite geographical conditions. One requires a large altitude difference, and the other requires a closed and pressure-resistant underground cavern. This geographical condition will have a long transmission distance from the power generation end and the power consumption end. In addition, hydrogen energy storage by electrolysis of water, battery energy storage, flywheel energy storage, super battery, etc. all have various problems, especially hydrogen energy storage by electrolysis of water, the power reduction rate is not high, the efficiency of electrolysis of water is about 80%, and the energy consumption of hydrogen liquefaction storage is high. What is important is that the efficiency of hydrogen power generation is subject to the efficiency of the thermal engine, the power generation efficiency is not higher than 50%, the overall power reduction rate is not higher than 40%, the technology is immature and the cost is high. This patent is a method invention, using liquid air for energy storage and using a Stirling engine as a bidirectional energy converter (refrigeration + power generation). Although the existing Stirling machine power generation efficiency is not higher than 40%, the refrigeration efficiency of the Stirling machine can be as high as 300% (the refrigeration process is a heat transfer process, so the efficiency is higher than 100%). The refrigeration efficiency greater than 100% perfectly compensates for the general heat engine efficiency of less than 50%. The overall power recovery rate can reach more than 60%, becoming a new and complete power storage technology solution. At the same time, the Stirling machine can be used as both a refrigerator and a generator for power recovery. At present, China has produced 310KW Stirling generators and 105KW Stirling refrigerators. There are no fundamental technical difficulties in amplifying power and combining the two machines. The high-temperature materials and high-temperature dynamic seals of the Stirling machine do not have high-temperature problems in the application of low-temperature liquid air energy storage. The first characteristic of the Stirling machine is that the refrigeration efficiency is higher than the existing refrigeration method, which is a new refrigeration method. The second characteristic of the Stirling engine is that it has a thermal engine efficiency that is lower than that of a diesel engine but higher than that of a gasoline engine, which is generally not higher than 40%. It is generally not significantly lower than the power reduction rate of hydrogen by electrolysis of water. At the same time, the refrigeration efficiency can be as high as 300%, which compensates for the thermal engine efficiency of the Stirling engine, which is generally not higher than 40%. However, electrolysis of water does not have a refrigeration efficiency compensation higher than 100%. The only way to replace the power generation of hydrogen combustion reduction with high-cost and technologically immature hydrogen fuel cells is to replace the thermal engine efficiency of hydrogen combustion power generation, which is generally not higher than 40%. The third characteristic of the Stirling engine is that it is larger than an internal combustion engine. Compared with energy storage methods such as pumped storage power stations, compressed air energy storage, hydrogen energy storage by electrolysis of water, flow batteries, and super batteries, it can only have the advantage of small size. The fourth characteristic of the Stirling engine is that it has a large heat dissipation area. When the Stirling engine stores energy and reduces electricity, it uses the external ambient temperature, and the large heat dissipation area becomes the advantage of a large heat exchange area. The fifth characteristic of the Stirling machine is its slow response speed. When the Stirling machine (cooling + power generation) is in two-way standby mode, it does not start the warm-up, but switches between the electric cooling or temperature difference power generation states while maintaining the high and low temperature difference conditions, and can achieve fast two-way switching.The advantages of the Stirling engine are simple structure, reliable operation, no emission of working fluid, clean and efficient, few moving parts, low noise, wide adaptability of heat source, and low cost. Similar technology, the Chinese Academy of Sciences used liquid air to heat up and expand to drive a multi-stage centrifugal compressor to generate electricity, but the test results were not ideal and required supplementary heating. The reason was that the wrong energy conversion machinery (refrigeration + power generation) was selected. When the working fluid in the multi-stage centrifugal compressor expanded to generate electricity, a large amount of heat was absorbed. Since the distance between the stages of the multi-stage centrifugal compressor is only one metal layer, the heat absorption cooled the working fluid that heated up and expanded before the stage, and the original goal of using environmental heat as a heat source for power generation was not achieved. As a result, the test results required supplementary heating. Therefore, the Chinese Academy of Sciences retreated to realize the underground cavity energy storage method of compressed air circulation hot oil supplementary heating. Although supplementary heating is not required, it also did not achieve effective power generation as a heat source. The invention of this patent (liquid air, Stirling refrigeration + power generation, bidirectional long-term energy storage machine) has found the right energy conversion machinery, overcoming the situation that multi-stage centrifugal compressors must require heat supplementation. It can be widely and geographically unrestricted distributed multi-point deployment at the power generation end, the power consumption end, and the power transmission end. It can balance power generation fluctuations (especially photovoltaic and wind power generation fluctuations), transmission fluctuations (especially ensuring the stability of transmission power), and power consumption fluctuations (especially balancing the peaks and valleys of power consumption). It has broad application prospects and can widely solve the problem of storing electricity during peak and valley fluctuations in power. Summary of the invention

[0003] This patent is a method invention, which uses liquid air (key point 1) to store in a low-temperature insulated storage tank (key point 2) for long-term energy storage, and uses a Stirling machine (key point 3) as a two-way energy conversion machine that is both a refrigerator for refrigeration energy storage (key point 3) and a prime mover for cold and hot power generation during power reduction (key point 4). (The two-way switching of the refrigerator and the generator is achieved by electrical control, which is similar to the electrical control system of the hydraulic generator of the pumped storage power station. The electrical control method is not included in the content of this invention.) Although the existing Stirling machine power generation efficiency is not higher than 40%, the refrigeration efficiency of the Stirling machine can be as high as 300%, perfectly compensating for the heat engine efficiency generally lower than 50% with a refrigeration efficiency greater than 100% (key point 5), and the overall power reduction rate can reach more than 60%, becoming a new and complete power storage technology solution. The high temperature end of the Stirling machine can be room temperature air (key point 6) or room temperature water (key point 7) or heat stored at the high temperature end during refrigeration (key point 8) or other heat sources (key point 9) ------ the conventional room temperature air solution, the low temperature end is liquid air or LNG after air refrigeration (key point 10) or other cold objects generated at the low temperature end during refrigeration (key point 11) or other cold sources (key point 12) ------ the conventional liquid air solution after air refrigeration. The Stirling machine can be a free piston (key point 13) + linear motor, or a piston (key point 14) + crankshaft + rotary motor, or a piston + inclined plate (key point 15) + rotary motor ------ the conventional free piston + linear motor solution. The combined energy storage bidirectional energy conversion of liquid air and Stirling machine stores electric energy technology solution (key point 16).

Claims

1. Use liquid air (key point 1) stored in cryogenic insulated tanks (key point 2) for long-term energy storage.

2. Use the Stirling engine (key point 3) as a bidirectional energy conversion machine that is both a refrigerator for refrigeration energy storage (key point 3) and a prime mover for cold and hot power generation during power recovery (key point 4).

3. Although the existing Stirling engine power generation efficiency is no higher than 40%, the refrigeration efficiency of the Stirling engine can be as high as 300%, perfectly compensating the thermal engine efficiency of generally less than 50% with a refrigeration efficiency greater than 100% (key point 5). The overall power recovery rate can reach more than 60%, becoming a new and complete power storage technology solution.

4. The high temperature end of the Stirling engine can be room temperature air (key point 6) or room temperature water (key point 7) or hot objects stored at the high temperature end during refrigeration (key point 8) or other heat sources (key point 9) ------ the conventional room temperature air solution, and the low temperature end is liquid air or LNG after air refrigeration (key point 10) or other cold objects generated at the low temperature end during refrigeration (key point 11) or other cold sources (key point 12) ------ the conventional liquid air solution after air refrigeration.

5. The Stirling machine can be a free piston (key point 13) + linear motor, a piston (key point 14) + crankshaft + rotary motor, or a piston + inclined plate (key point 15) + rotary motor - the conventional free piston + linear motor solution.

6. Combined technical solution of liquid air and Stirling engine energy storage and bidirectional energy conversion (Key Point 16).