Double-working-medium circulating power system and control method thereof

Abstract

The invention discloses a double-working-medium circulating power system and a control method thereof. The power system is composed of an air liquefaction circulating system, a power circulating system, a heat pump system, an automatic controller, a first cold box and a second cold box. The air liquefaction circulating system consists of an air filter, an air compressor, a molecular sieve exchanger, a countercurrent heat exchanger and a first liquid storage tank; the hydrogen working medium power circulation system is composed of a second liquid storage tank, a liquid pump, a heat exchanger and an air cylinder expansion machine. The heat pump system is composed of an air compressor, a refrigeration expansion machine, an evaporator and a condenser. And the automatic controller is used for controlling the power system. The heat engine efficiency of an existing Carnot cycle is less than 50%, and according to the double-working-medium cycle power system, the temperature of a low-temperature heat source of the Carnot cycle is reduced to-192 DEG C from the environment temperature, heat sources at the environment temperature or above can become high-temperature heat sources of the Carnot cycle, environment energy can be developed conveniently, and zero-carbon, distributed, free and free energy sources can be obtained.

Description

Technical Field

[0001] The invention belongs to the field of power engineering, and in particular relates to a dual-medium circulation power system and a control method thereof. Background Art

[0002] The 19th century was the era when steam engines began to be widely used. French engineer Nicolas Sadi Carnot conducted in-depth research on the efficiency of steam engines. On May 12, 1824, he published a paper entitled "On the Power of Fire and Water and the Machines Suitable for Producing Such Power", in which he published the Carnot cycle theory, which is the earliest thermodynamic theory. For 200 years, the Carnot cycle theory has played a huge role in promoting the development of human thermal energy and power. The Carnot cycle theory attributes the heat engine cycle to a power cycle between two heat sources (high-temperature heat source and low-temperature heat source). The heat engine absorbs heat Q1 from the high-temperature heat source with a temperature of T1, and the heat engine positive cycle performs work to generate power W. Part of the heat Q2 is transferred to the low-temperature heat source with a temperature of T2. The output work W = Q1-Q2, and the heat engine efficiency η = (Q1-Q2) / Q1 = (T1-T2) / T1≤1. The efficiency formula gives two situations where the efficiency is equal to 1: the temperature T2 of the low-temperature heat source is 0K, or the temperature T2 of the high-temperature heat source is ∞. Since both situations are impossible, the efficiency of the heat engine can only be less than 1. At the same time, it is pointed out that since it is difficult to change the temperature T2 of the low-temperature heat source (cooling water, air), the only way to improve the efficiency of the heat engine is to increase the temperature T1 of the high-temperature heat source.

[0003] Under the guidance of Carnot cycle theory, thermal power has embarked on a technical route of increasing the temperature of high-temperature heat sources. At present, the temperature of the thermal power Rankine cycle has reached 620°C. my country's next goal for thermal power technology is to overcome 700°C. The temperature of the Brayton cycle of the gas turbine has reached 1250°C. The temperature of the high-temperature heat source of magnetohydrodynamic power generation has exceeded 3000°C. The highest temperature of controlled nuclear fusion has reached tens of millions or even hundreds of millions of degrees Celsius. In the process of increasing the temperature of high-temperature heat sources, the efficiency of thermal power systems has been continuously improved from 3% to 5% of early steam engines. At present, the efficiency of the ultra-supercritical Rankine cycle of thermal power is close to 50%, and the efficiency of the Brayton cycle of supercritical CO2 reaches 50% when the temperature of the high-temperature heat source exceeds 650°C.

[0004] In order to continuously improve the utilization rate of thermal energy, humans have done a lot of exploration. In terms of low-temperature waste heat utilization, the organic Rankine cycle power generation technology ORC has been developed. It uses the low boiling point characteristics of organic working fluids to obtain higher steam pressure under the heating of a low-temperature high-temperature heat source (80-300°C), driving the expander to generate electricity. Screw expanders or centripetal expanders are used to meet the requirements of steam and liquid two-phase flow. In the process of condensation and liquefaction of the exhaust steam entering the condenser after expansion, due to the limitation of cooling water temperature, the lowest heat source temperature that can be used by ORC power generation technology is about 80°C, and the thermal efficiency is about 8%, which is of great significance for the exploration of utilizing low-quality waste heat.

[0005] In order to explore the development and utilization of environmental energy, as early as the 1870s and 1980s, British inventor John Gamgee used air energy to pressurize and heat liquid ammonia to vaporize and expand to provide power for ships, and used seawater to cool the exhaust steam. However, the experiment failed because the temperature of ammonia liquefaction was -33°C and seawater could not liquefy it. He was the earliest developer of environmental energy. Since the 20th century, humans have developed ocean temperature difference power generation and LNG low-temperature power generation technology. Ocean temperature difference power generation uses surface seawater as heat source (the seasonal variation of water temperature in the South my country Sea is between 22℃ and 29℃ all year round) and deep seawater of 400 to 1000 meters (water temperature is 4℃ to 7℃ all year round) as low temperature cold source. It can form a power system without burning fossil energy, but it has the characteristics of long deep seawater pipelines, large investment, small temperature difference and low thermal efficiency. LNG low temperature power generation technology uses seawater as heat source and the cold energy released in the gasification process of liquefied natural gas (LNG) at -162℃ as the low temperature cold source of the power cycle system, realizing the full utilization of the cold energy released in the gasification process of LNG and the development of environmental energy. It has opened up a technical route for low temperature circulation for the development of power engineering, expanding the power cycle system from the traditional circulation in the high temperature area above the ambient temperature to below the ambient temperature, which is of great significance.

[0006] In order to develop environmental energy, the inventor's invention patent application "A power generation system and control method for cold power engineering" (application number: 202311017125.0) provides a low-temperature power circulation system composed of a low-temperature liquid storage tank, a liquid pump, an environmental energy vaporizer, an expander and its generator set in series, and a technical solution for condensing exhaust steam by a heat pump. The liquid pump extracts low-temperature working fluid from the low-temperature liquid storage tank, pressurizes it, and sends it to the environmental energy vaporizer to heat it into high-pressure steam, and then expands and works through the expander to return to the liquid storage tank. The heat pump condenses the exhaust steam and transfers the heat of the exhaust steam to the circulating working fluid at the outlet of the liquid pump. In the demonstration project, it was found that the heat pump was used to transfer the heat of the exhaust steam to the circulating working fluid at the outlet of the liquid pump. The increase in the temperature of the circulating working fluid at the outlet of the liquid pump would prevent the heat transfer; for this reason, the present invention improves the circulation system of the patent application and proposes a dual-working fluid circulation power system, which creates a constant temperature low-temperature heat source for the heat transfer of the heat pump condensed exhaust steam, so that the low-temperature power circulation system for the purpose of environmental energy development can be realized. Summary of the invention

[0007] Based on the above new technical routes and research, a dual-fluid low-temperature cycle power system and a control method thereof are provided to reduce the exhaust steam heat of the power cycle system.

[0008] In order to achieve the above tasks, the present invention adopts the following technical solutions:

[0009] On the one hand, the present invention provides a semi-open dual-working medium cycle power system, which is composed of an air liquefaction cycle system, a hydrogen working medium power cycle system, a heat pump system and an automatic controller KZQ, a first cold box LX1 and a second cold box LX2; wherein:

[0010] The air liquefaction circulation system is composed of an air filter GLQ, an air compressor KYJ, a molecular sieve exchanger JHQ, a countercurrent heat exchanger NLHRQ, and a first liquid storage tank CYG1; wherein the first liquid storage tank CYG1 is provided with a liquid-air outlet L-Air out, an air supply port To LX to a cold box, and a control valve; the air inlet Air in to the inlet and outlet of the air filter GLQ, to the inlet and outlet of the air compressor KYJ, to the inlet and outlet of the molecular sieve exchanger JHQ, to the inlet and outlet of the high-temperature channel of the countercurrent heat exchanger NLHRQ, and to the inlet of the first liquid storage tank CYG1 are connected in series in sequence;

[0011] The power circulation system of the hydrogen working medium is composed of a second liquid storage tank CYG2, a liquid pump YB, a heat exchanger HR, and at least one two-stroke cylinder expander QG for air intake, work and compression and exhaust; wherein, the liquid outlet of the second liquid storage tank CYG2 to the low-temperature inlet and outlet of the countercurrent heat exchanger NLHRQ, to the inlet and outlet of the cylinder expander QG, and to the inlet of the second liquid storage tank CYG2 are connected in series in sequence, the liquid pump YB is installed at the liquid outlet of the second liquid storage tank CYG2, the heat exchanger HR is installed in the saturated liquid in the first liquid storage tank CYG1, and is connected in series between the liquid pump YB and the low-temperature inlet of the countercurrent heat exchanger NLHRQ; liquid hydrogen is stored in the second liquid storage tank CYG2;

[0012] The heat pump system is composed of a compressor YQJ, a refrigeration expansion machine PZ, an evaporator ZF, and a condenser LN; wherein the condenser LN is arranged in the liquid working medium area at the bottom of the first liquid storage tank CYG1, and the evaporator ZF is arranged in the gaseous working medium area at the top of the second liquid storage tank CYG2, and the outlet of the compressor YQJ is connected in series to the inlet and outlet of the condenser LN, to the inlet and outlet of the refrigeration expansion machine PZ, to the inlet and outlet of the evaporator ZF, and to the inlet of the compressor YQJ; the heat pump system is filled with helium as a circulating working medium, and the compressor YQJ, the refrigeration expansion machine PZ and its driving motor are coaxially operated;

[0013] The countercurrent heat exchanger NLHRQ is installed in the first cold box LX1, and the first liquid storage tank CYG1, the second liquid storage tank CYG2, the liquid pump YB, the compressor YQJ, the refrigeration expansion machine PZ, and the cylinder expansion machine QG are all installed in the second cold box LX2; an outlet To cool for sending cold air to the outside is provided on the top of the first cold box LX1; the top of the second cold box LX2 is connected to the bottom of the first cold box LX1.

[0014] Automatic controller KZQ is used to automatically control the temperature, pressure, flow and other parameters of each part of the system to maintain them at the set values.

[0015] In a second aspect, the present invention provides a control method for a power system with a semi-open dual-working medium cycle. The power system with a semi-open dual-working medium cycle according to the present invention specifically includes the following operations:

[0016] The operation of the air compressor KYJ and the molecular sieve exchanger JHQ in the automatic control system I inhales air from the air inlet Air in, filters impurities in the air through the air filter GLQ, pressurizes through the air compressor KYJ, sends it to the molecular sieve exchanger JHQ to filter moisture and CO2 in the air, enters the high-temperature channel of the countercurrent heat exchanger NLHRQ to release heat and cool to the outlet for liquefaction, and then flows into the first liquid storage tank CYG1;

[0017] The liquid pump YB of the power circulation system of the hydrogen working medium is automatically controlled, and the liquid hydrogen is extracted from the second liquid storage tank CYG2, pressurized, and then sent to the heat exchanger HR and the countercurrent heat exchanger NLHRQ to absorb heat and gasify into high-pressure normal-temperature steam, and then enter the cylinder expansion machine QG, and the inlet valve and outlet valve of the cylinder expansion machine QG are automatically controlled to make the cylinder expansion machine QG operate between the two strokes of intake work and compression exhaust, and work is performed externally, and the exhaust steam after work is discharged into the second liquid storage tank CYG2;

[0018] The heat pump system is automatically controlled so that the compressor YQJ compresses the working medium helium filled during the installation process of the heat pump system, and the temperature rises to a temperature exceeding that of the liquid air in the first liquid storage tank CYG1, flows through the condenser LN to release heat to the liquid air, and then passes through the expander PZ to reduce the pressure and temperature to the outlet for liquefaction, and then flows through the evaporator ZF to absorb heat and vaporize, and automatically circulates to bring the exhaust steam heat in the second liquid storage tank CYG2 to the first liquid storage tank CYG1; part of the liquid air in the first liquid storage tank CYG1 is heated and vaporized to become low-temperature cold air, which is successively sent to the second cold box LX2 and the first cold box LX1, and finally sent out as cold air To cool, and the unvaporized liquid air is discharged to the outside from the liquid air outlet L-Air out;

[0019] Automatic controller KZQ automatically controls the pressure, temperature and flow of each part of the system to run at the preset values.

[0020] In a third aspect, the present invention provides a closed dual-working fluid cycle power system, which is composed of a high-temperature working fluid circulation system, a low-temperature working fluid circulation system, a group of heat pumps, an automatic controller, a first cold box LX1 and a second cold box LX2; wherein:

[0021] The high-temperature working medium circulation system is composed of at least one first liquid storage tank CYG1, a first liquid pump YB1, a jet pump SLB, a group of heat exchangers HRQ and a group of countercurrent heat exchangers NLHRQ; wherein the liquid working medium outlet of the first liquid storage tank CYG1 is connected in series to the inlet and outlet of the first liquid pump YB1, to the inlet and outlet of the jet pump SLB, to the inlet and outlet of the heat exchanger HRQ, to the high-temperature channel inlet and outlet of the countercurrent heat exchanger NLHRQ, and to the inlet of the first liquid storage tank CYG1; the air intake of the jet pump SLB is connected to the top exhaust port of the first cold box LX1;

[0022] The low-temperature working medium circulation system is composed of at least one second liquid storage tank CYG2, a second liquid pump YB2, a second heat exchanger HR2, an expander T and a generator connected thereto; wherein the liquid working medium outlet of the second liquid storage tank CYG2, the inlet and outlet to the second liquid pump YB2, the inlet and outlet of the second heat exchanger HR2, the inlet and outlet to the low-temperature channel of the countercurrent heat exchanger NLHRQ, the inlet and outlet to the expander T, and the inlet to the low-temperature liquid storage tank CYG2 are connected in series in sequence. The second heat exchanger HR2 is installed at the bottom of the first liquid storage tank CYG1; the boiling point temperature of the working medium stored in the first liquid storage tank CYG1 must be higher than the boiling point temperature of the working medium in the second liquid storage tank CYG2;

[0023] Heat pump: It consists of a compressor YQJ, a first heat exchanger HR1 arranged at the bottom of the liquid storage tank CYG1, and a refrigeration expansion machine PZ; the air outlet of the second liquid storage tank CYG2, the inlet and outlet of the compressor YQJ, the inlet and outlet of the first heat exchanger HR1, the inlet and outlet of the refrigeration expansion machine PZ, and the inlet of the second liquid storage tank CYG2 are connected in series in sequence, and the compressor YQJ, the refrigeration expansion machine PZ and its driving motor operate coaxially; an exhaust port To LX is arranged on the top of the first liquid storage tank CYG1, and the saturated air generated by the heat of the heat pump in the first liquid storage tank CYG1 is discharged from the exhaust port To LX on the top of the first liquid storage tank CYG1 to the second cold box LX2; the first heat exchanger HR1 is installed at the bottom of the first liquid storage tank CYG1.

[0024] The countercurrent heat exchanger NLHRQ is installed in the first cold box LX1, and the first liquid storage tank CYG1, the second liquid storage tank CYG2, the first liquid pump YB1, the second liquid pump YB2, the compressor YQJ, the refrigeration expander PZ and the expander T are installed in the second cold box LX2. The top of the second cold box LX2 is connected to the bottom of the first cold box LX1.

[0025] Automatic controller KZQ is used to keep the temperature, pressure, flow and other parameters of each part of the automatic system at the set value.

[0026] In a fourth aspect, the present invention provides a control method for a closed dual-fluid cycle power system, based on the closed dual-fluid cycle power system according to claim 6 or 7, specifically comprising the following operations:

[0027] The first liquid pump YB1 in the automatically controlled high-temperature working medium circulation system extracts a certain amount of liquid working medium from the first liquid storage tank CYG1 and sends it to the jet pump SLB. The jet pump SLB extracts a certain amount of gaseous working medium from the first cold box LX1, and sends the mixed working medium to the heat exchanger HRQ for heating and gasification to become normal-temperature working medium gas. The normal-temperature working medium gas then flows into the high-temperature channel of the countercurrent heat exchanger NLHRQ, transfers the heat to the low-temperature channel of the countercurrent heat exchanger NLHRQ, cools down in the high-temperature channel of the countercurrent heat exchanger NLHRQ, and liquefies and flows into the first liquid storage tank CYG1, completing the cycle.

[0028] The second liquid pump YB2 of the automatic control low-temperature working medium circulation system extracts liquid working medium from the second liquid storage tank CYG2, sends it through the low-temperature channel of the second heat exchanger HR2 and the countercurrent heat exchanger NLHRQ to absorb heat and gasify into high-pressure steam, and the exhaust steam after expansion and work by the expander T flows into the second liquid storage tank CYG2 to complete the cycle;

[0029] The compressor YQJ of the automatic control heat pump extracts the working medium exhaust steam in the second liquid storage tank CYG2, compresses and heats it, and then flows through the heat exchanger ⅠHR1 arranged in the first liquid storage tank CYG1, transfers the exhaust steam heat to the first liquid storage tank CYG1, and then liquefies through the refrigeration expansion machine PZ and flows back to the second liquid storage tank CYG2;

[0030] The automatic controller KZQ controls the pressure, temperature and flow of each part of the system to run at the preset values.

[0031] In the fifth aspect, the present invention provides a power system with a closed dual-fluid circulation. When the circulating working fluid is selected, in the power system with a closed dual-fluid circulation, the working fluid output by the second liquid pump YB2 of the low-temperature working fluid circulation system is directly transported to the countercurrent heat exchanger NLHRQ without causing the circulating working fluid of the high-temperature working fluid circulation system to form dry ice in the channel of the countercurrent heat exchanger NLHRQ. Then the power system with a closed dual-fluid circulation does not include the heat exchanger HR2.

[0032] In a sixth aspect, the present invention provides a closed dual-fluid cycle power system, which is obtained by replacing the heat pump in the closed dual-fluid cycle power system with a heat pump system of a semi-open dual-fluid cycle power system.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The system and method of the present invention relatively reduce the exhaust steam heat of the working fluid gas by selecting the circulating working fluid. By recovering the condensation heat of the exhaust steam, the dual-working fluid cycle power system no longer discharges the exhaust steam heat to the environment, so that the theoretical thermal efficiency of the entire power cycle system is equal to 1. The power cycle system can draw heat energy from high-temperature heat sources such as boilers and burners that burn fossil fuels at a temperature higher than the ambient temperature, or solar thermal collectors, and can also draw heat energy from environmental thermal mass such as water, air, geothermal energy, and ground temperature at ambient temperature as a heat source to drive the power system. In particular, the power system using thermal mass at ambient temperature as a heat source can achieve revolutionary progress in zero-carbon, distributed, free, and free energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is the principle diagram of the power system of the semi-open dual-working medium cycle;

[0036] Figure 2It is a PH schematic diagram of a power system of a semi-open dual-working medium cycle;

[0037] Figure 3 It is the PH diagram of hydrogen working medium in the power system of semi-open dual working medium cycle;

[0038] Figure 4 It is the principle diagram of the power system of the closed dual-working medium cycle;

[0039] Figure 5 PH schematic diagram of the power system with closed dual-fluid cycle.

[0040] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0041] The following is a further explanation of the dual-fluid cycle power system and the control method thereof of the present invention in conjunction with the accompanying drawings.

[0042] like Figure 1 As shown, the present invention provides a semi-open dual-working medium cycle power system, which consists of an air liquefaction cycle system (hereinafter referred to as system I), a hydrogen working medium power cycle system (hereinafter referred to as system II), a heat pump system and an automatic controller KZQ, a first cold box LX1 and a second cold box LX2; wherein:

[0043] System I is composed of an air filter GLQ, an air compressor KYJ, a molecular sieve exchanger JHQ, a countercurrent heat exchanger NLHRQ, and a first liquid storage tank CYG1; wherein the first liquid storage tank CYG1 is provided with a liquid-air outlet L-Air out, an air supply port To LX to a cold box, and a control valve; the air inlet Air in to the inlet and outlet of the air filter GLQ, to the inlet and outlet of the air compressor KYJ, to the inlet and outlet of the molecular sieve exchanger JHQ, to the inlet and outlet of the high-temperature channel of the countercurrent heat exchanger NLHRQ, and to the inlet of the first liquid storage tank CYG1 are connected in series in sequence.

[0044] System II is composed of a second liquid storage tank CYG2, a liquid pump YB, a heat exchanger HR, and at least one two-stroke cylinder expander QG for intake work and compression exhaust; wherein, the liquid outlet of the second liquid storage tank CYG2 to the low-temperature inlet and outlet of the countercurrent heat exchanger NLHRQ, to the inlet and outlet of the cylinder expander QG, and to the inlet of the second liquid storage tank CYG2 are connected in series in sequence, the liquid pump YB is installed at the liquid outlet of the second liquid storage tank CYG2, the heat exchanger HR is installed in the saturated liquid in the first liquid storage tank CYG1, and is connected in series between the liquid pump YB and the low-temperature inlet of the countercurrent heat exchanger NLHRQ, the heat exchanger HR is used to make the liquid hydrogen output by the liquid pump YB absorb heat to increase the temperature to about -212°C, and a temperature difference of 20°C is set between the liquid air outlet of the countercurrent heat exchanger NLHRQ; liquid hydrogen is stored in the second liquid storage tank CYG2.

[0045] The heat pump system is composed of a compressor YQJ, a refrigeration expansion machine PZ, an evaporator ZF, and a condenser LN; wherein, the condenser LN is arranged in the liquid working medium area at the bottom of the first liquid storage tank CYG1, and the evaporator ZF is arranged in the gaseous working medium area at the top of the second liquid storage tank CYG2. The outlet of the compressor YQJ is connected in series to the inlet and outlet of the condenser LN, to the inlet and outlet of the refrigeration expansion machine PZ, to the inlet and outlet of the evaporator ZF, and to the inlet of the compressor YQJ; the heat pump system is filled with helium as a circulating working medium, and the compressor YQJ, the refrigeration expansion machine PZ and its driving motor are coaxially operated. In the heat pump system, the condenser LN is used for heat dissipation of the heat pump system, the evaporator ZF is used for heat absorption of the heat pump system, and the refrigeration expansion machine PZ is used for refrigeration expansion of the heat pump system.

[0046] The countercurrent heat exchanger NLHRQ is installed in the first cold box LX1, the first liquid storage tank CYG1, the second liquid storage tank CYG2, the liquid pump YB, the compressor YQJ, the refrigeration expansion machine PZ, and the cylinder expansion machine QG are all installed in the second cold box LX2; the top of the first cold box LX1 is provided with an outlet To cool for sending cold air to the outside. The top of the second cold box LX2 is connected to the bottom of the first cold box LX1.

[0047] The automatic controller KZQ is used to control the power system of the semi-open dual-working medium cycle of the present invention.

[0048] The products selected for each part of the present invention are as follows:

[0049] The automatic controller KZQ adopts the existing controller.

[0050] The first cold box LX1 and the second cold box LX2 both use the cold screen of the equipment operating in the low temperature area in the prior art. The box body has heat insulation ability and is filled with low temperature gas to reduce the loss of cold during the operation of the low temperature equipment. The air supply port To LX to the cold box is located in the cold box 2. The top of the cold box 2 is connected to the bottom of the cold box 1. To cool is located at the top of the cold box 1. In this way, when the system is running, the low temperature gas (-192℃) To LX in the first liquid storage tank CYG1 is first discharged to the second cold box LX2, and then flows into the first cold box LX1 to deliver cold air from its bottom, and finally sent to the machine room, cold storage, etc. by To cool at the top of the first cold box LX1.

[0051] The first liquid storage tank CYG1 and the second liquid storage tank CYG2 both use low-temperature (liquid air -192°C or liquid hydrogen -253°C) liquid storage containers, preferably Dewar tanks; the liquid pump YB uses a low-temperature liquid pump; the heat exchanger HR (preferably a tubular heat exchanger) is used to allow the liquid hydrogen output by the liquid pump YB to absorb a certain amount of heat to increase the temperature to about -212°C, and a 20°C temperature difference is set between the liquid air outlet of the countercurrent heat exchanger NLHRQ to prevent the liquid air from becoming solid snowflakes due to excessively low temperature before the outlet of the countercurrent heat exchanger NLHRQ, thereby blocking the flow channel.

[0052] The air inlet valve arranged at the inlet of the cylinder expander QG is connected to the outlet of the low-temperature channel of the countercurrent heat exchanger NLHRQ, and the exhaust valve arranged at the outlet of the cylinder expander QG is connected to the inlet of the second liquid storage tank CYG2; the boiling point temperature of the working fluid stored in the first liquid storage tank CYG1 needs to be higher than the boiling point temperature of the working fluid in the second liquid storage tank CYG2 to ensure that the working fluid of system I can be cooled and liquefied in the countercurrent heat exchanger NLHRQ. The difference between the boiling point temperature of hydrogen and the boiling point temperature of air constitutes the temperature difference required by the present invention well, and the gas constant of hydrogen is the largest among common gases. Under the same unit flow rate, the hydrogen working medium cycle can obtain the highest specific power. It can be seen from the following specific embodiments that the specific power of hydrogen working medium is higher than that of the prior art, and it is a very ideal low-temperature circulation working medium; but once hydrogen leaks, it is easy to burn, and the shaft end of the turbine expander in the prior art is easy to leak, so a cylinder expander QG with good system sealing is selected to explain the principle. If the shaft end of the turbine expander can be leak-free or other corresponding measures are taken and other expanders can solve the problem of working medium leakage, other expanders can also be used.

[0053] The present invention provides a control method for a semi-open dual-fluid cycle power system, which specifically includes the following operations:

[0054] The operation of the air compressor KYJ and the molecular sieve exchanger JHQ in the automatic control system Ⅰ inhales air from the air inlet Air in, filters the impurities in the air through the air filter GLQ, pressurizes through the air compressor KYJ, sends it to the molecular sieve exchanger JHQ to filter the moisture and CO2 in the air, enters the high-temperature channel of the countercurrent heat exchanger NLHRQ to release heat and cool down, and flows into the first liquid storage tank CYG1 after liquefaction;

[0055] Automatic control system II liquid pump YB, extracts liquid hydrogen from the second liquid storage tank CYG2, pressurizes it (the pressure value is different for different working fluids, and the pressure is 7.8MPa in the embodiment of the present invention using hydrogen as the working fluid), and then sends it to the heat exchanger HR and the countercurrent heat exchanger NLHRQ to absorb heat and gasify into high-pressure (different working fluids have different values) room-temperature steam, and enters the cylinder expansion machine QG, and automatically controls the inlet valve and outlet valve of the cylinder expansion machine QG to make the cylinder expansion machine QG operate between the two strokes of intake work and compression exhaust, and work externally, and the exhaust steam after work is discharged into the second liquid storage tank CYG2;

[0056] The heat pump system is automatically controlled so that the compressor YQJ compresses the working medium helium filled during the installation process of the heat pump system, and the temperature rises to a temperature exceeding that of the liquid air in the first liquid storage tank CYG1, flows through the condenser LN to release heat to the liquid air, and then passes through the evaporator ZF to absorb heat and vaporize after reducing the pressure and temperature to the outlet through the expander PZ, and automatically circulates to bring the exhaust steam heat in the second liquid storage tank CYG2 to the first liquid storage tank CYG1 (that is, it is achieved through the process of evaporator ZF absorbing heat and condenser LN releasing heat); part of the liquid air in the first liquid storage tank CYG1 is heated and vaporized to become low-temperature cold air, which is successively sent to the second cold box LX2 and the first cold box LX1, and finally sent to the digital computer room, central air conditioning, low-temperature cold storage, etc. The unvaporized liquid air is discharged to the outside from the liquid air outlet L-Air out;

[0057] Automatic controller KZQ automatically controls the pressure, temperature and flow of each part of the system to run at the preset values.

[0058] Figure 2 It is a PH schematic diagram of the power system of the semi-open dual-working medium cycle of the present invention, which includes an air liquefaction process, a power cycle system, and a heat pump system circulation line, wherein line Ⅰ is the saturation line of air, 123 is the air liquefaction process line, 1-2 is the pressurized adsorption process line of the air compressor KYJ and the molecular sieve exchanger JHQ of system Ⅰ, and 2-3 is the air cooling and liquefaction line; line Ⅱ is the saturation line of hydrogen, lines 4567 are the circulation lines of the power system, 4-5 is the pressurization process of the liquid pump YB of system Ⅱ, 5-6 is the isobaric endothermic process line of hydrogen, and 6-7 is the isentropic expansion line of hydrogen; line Ⅲ is the heat pump system circulation line, which has isentropic compression, isobaric heat release, isentropic expansion, and isobaric endothermic process; these processes belong to the coupling of the prior art, and those skilled in the art can implement them according to conventional means in the art, and will not be described in detail here.

[0059] Figure 3 This is the PH diagram of hydrogen working fluid in the power system of semi-open dual working fluid cycle. The base map is provided by Ref Prop software. 4567 in the figure is the power cycle line of hydrogen. By checking the parameters of each point on the cycle line in the figure, combined with Figure 1 , Figure 2 The operation of the entire system is illustrated as follows (for example only and not to limit the present invention):

[0060] 1. Air liquefaction circulation system process: natural air is sucked in from the air inlet Air in, filtered through the air filter GLQ for impurities, pressurized by 0.7MPa to 0.9MPa by the air compressor KYJ, and sent to the molecular sieve exchanger JHQ to remove moisture and carbon dioxide in the air. If it flows into the high-temperature channel in the countercurrent heat exchanger NLHRQ at a temperature of 20°C, the temperature gradually decreases from top to bottom to -192°C for liquefaction, and then flows into the first liquid storage tank CYG1;

[0061] 2. Hydrogen working medium power circulation system, liquid hydrogen is extracted from the second liquid storage tank CYG2 by liquid pump YB, pressurized to 7.8MPa, and flows into the low-temperature channel of the countercurrent heat exchanger NLHRQ, absorbing heat from bottom to top and heating up to gasify. When the air temperature at the inlet of the high-temperature channel of the countercurrent heat exchanger NLHRQ is 20℃, the temperature difference with the outlet of the low-temperature channel is set at 20℃. The hydrogen at the outlet of the low-temperature channel is 0℃ and the pressure is 7.8Mpa, and flows into the cylinder expander QG to expand and do work. The exhaust steam after doing work flows into the second liquid storage tank CYG2 to complete the cycle; from Figure 3 The parameters of each node of the power cycle system are listed in Table 1:

[0062] Table 1 Parameters of the hydrogen working medium power cycle system coupled with the air liquefaction process

[0063]

[0064] If the cylinder expander of the power cycle system is connected to a generator set, the power generation capacity can be obtained:

[0065] W=H 67 / η pz ×η=2800×0.90=2520kW;

[0066] According to the maximum specific enthalpy of the power cycle system of 3600kJ, the air flow rate of the air liquefaction cycle system is calculated as follows:

[0067] When the ambient temperature is 20℃, the density is 1.205kg / m3, the specific heat capacity Cp is 1.005kj / kg.℃, the boiling point of liquid air is -192℃, the density is 960kg / m3, and the heat of vaporization is 196.742kJ / kg; the heat released before liquefaction of each kg of air is the sum of the specific heat and the heat of vaporization:

[0068] Qc+Qy=(20+192)×1.005+196.742=409.8kJ / kg

[0069] The air flow rate in heat balance with the power cycle system is:

[0070] S = [3600-(1000×7.8×1 / 960)] / 409.8 = 8.76 kg / s (wherein: theoretical compression work of the liquid pump Np = (1000×7.8×1 / 960) = 8.125 kW; actual compression work: N = 8.125 / 0.85 = 9.6 kW);

[0071] 3. Heat pump system: The heat pump system consists of compressor YQJ, evaporator ZF, condenser LN, and refrigeration expander PZ; the liquid hydrogen temperature in the second liquid storage tank CYG2 is -253℃ (20k), the exhaust steam temperature is -220 (53k), the liquid air temperature in the first liquid storage tank CYG1 is -192℃ (81k), and the refrigeration coefficient is:

[0072] COPc = 53 / (81-53) = 1.89;

[0073] The heat output of the heat pump system to the liquid air is: Qc = H 74 +H 74 / COPc=800+800 / 1.89=1223 kJ / s;

[0074] The theoretical power consumption of compressor YQJ is Nc = (H 74 / COPc)=800 / 1.89=423kW;

[0075] The actual power consumption of compressor YQJ is: Nc' = Nc / η = 800 / 1.89 / 0.42 = 1008kW;

[0076] The power recovery of the refrigeration expander PZ is: Np = Nc × ηp = 423 × 0.9 = 380 kW;

[0077] The total energy consumption of the entire refrigeration system is: Nc'-Np = 1008-470 = 628kW;

[0078] The heat absorbed by the heat exchanger HR at the outlet of the liquid pump YB is:

[0079] Q HR =Cp×(T5'-T5)=14.27×(61-20)=585.07kJ;

[0080] The total heat received by the first liquid storage tank CYG1 is: Qc-Q HR =1223-585.07=637.93kJ;

[0081] 4. Balance calculation of heat pump output heat and air liquefaction volume:

[0082] The flow rate of liquefied air balanced with the power system is 8.76 kg / s;

[0083] The heat required for all gasification is: 196.742×8.76=1723.5kJ / s;

[0084] The total heat received by the first liquid storage tank CYG1 is 637.93 kJ;

[0085] The output of liquid air is sufficient to absorb the heat output of the heat pump: 673.93÷1723.5=39%.

[0086] Liquid air specific production: 8.76×61%=5.3kg / s;

[0087] Low temperature cooling air specific output: 8.76×39%=3.4kg / s;

[0088] Therefore, 39% of the liquid air produced in the air liquefaction process is vaporized through heat pump exhaust. The low-temperature (-192℃) air after vaporization can provide cooling to the system cold box, and then can be used as cooling air for digital computer rooms, cold storage, and central air conditioning. There is also 61% of liquid air products;

[0089] Energy efficiency of system power generation system β = power generation / (air compression work + liquid pump work + heat pump consumption)

[0090] =2520 / (1000×0.7×8.76÷960+9.6+628)=3.9;

[0091] Conclusion: When the sum of the power inputs of the air compressor, liquid pump and heat pump in the semi-open dual-fluid cycle power system of the present invention is 1 kW, 3.9 kW of electricity + 5.3 kg / s of liquid air + 3.4 kg / s of low-temperature (-192°C) cold air can be produced.

[0092] In the prior art, the Linde cycle used for air liquefaction requires repeated compression and cooling of the air, which consumes a lot of energy. The refrigeration of information rooms, cold storage, and central air conditioners are all large energy consumers. After industrial coupling, the air of the power system of the semi-open dual-medium cycle of the present invention can be liquefied in one cycle, and the efficiency is improved; the cold air required by information rooms, central air conditioners, low-temperature cold storage, etc. no longer consumes electricity, and the low-temperature cold air, a byproduct of the present invention, can provide cooling capacity, achieving multiple goals at one stroke, and industrial coupling has achieved good results.

[0093] The semi-open dual-fluid cycle power system of the present invention is essentially that its system I uses the ambient air in the air liquefaction process as the high-temperature heat source of the Carnot cycle, and uses the liquefied liquid air as the low-temperature heat source of the Carnot cycle, providing two heat sources for the Rankine cycle of the system II with hydrogen as the working fluid, and the liquefied air recovers the exhaust steam heat of the system II through the heat pump to liquefy the exhaust steam, so that the Rankine cycle of hydrogen at low temperature can be realized; the whole system is coupled with the countercurrent heat exchanger NLHRQ, the air liquefaction process of the system I obtains a cooling channel for cooling and liquefaction in the countercurrent heat exchanger, and the power cycle system of the system II obtains a channel for heating and gasifying hydrogen in the countercurrent heat exchanger, realizing the control target under the new technical route, and moving the low-temperature area of ​​the Carnot cycle from the ambient temperature of the prior art to the liquid hydrogen temperature zone of 20k; since the air liquefaction process is open and the hydrogen power cycle system is a closed-loop cycle, it is a semi-open dual-fluid cycle power system.

[0094] like Figure 4 As shown, the present invention provides a closed dual-working fluid cycle power system, which is composed of a high-temperature working fluid circulation system, a low-temperature working fluid circulation system, a group of heat pumps, an automatic controller, a first cold box LX1 and a second cold box LX2; wherein:

[0095] High-temperature working medium circulation system (hereinafter referred to as System I): consists of at least one first liquid storage tank CYG1, a first liquid pump YB1, a jet pump SLB, a group of heat exchangers HRQ and a group of countercurrent heat exchangers NLHRQ; wherein, the liquid working medium outlet of the first liquid storage tank CYG1 is connected in series in sequence to the inlet and outlet of the first liquid pump YB1, to the inlet and outlet of the jet pump SLB, to the inlet and outlet of the heat exchanger HRQ, to the high-temperature channel inlet and outlet of the countercurrent heat exchanger NLHRQ, and to the inlet of the first liquid storage tank CYG1; the air intake of the jet pump SLB is connected to the top exhaust port of the first cold box LX1.

[0096] Low temperature working medium circulation system (hereinafter referred to as system II): It is composed of at least one second liquid storage tank CYG2, a second liquid pump YB2, a second heat exchanger HR2, an expander T and a generator connected thereto; wherein the liquid working medium outlet of the second liquid storage tank CYG2, the inlet and outlet to the second liquid pump YB2, the inlet and outlet of the second heat exchanger HR2, the inlet and outlet to the low temperature channel of the countercurrent heat exchanger NLHRQ, the inlet and outlet to the expander T, and the inlet to the low temperature liquid storage tank CYG2 are connected in series in sequence. The second heat exchanger HR2 is installed at the bottom of the first liquid storage tank CYG1;

[0097] The boiling point temperature of the working fluid stored in the first liquid storage tank CYG1 needs to be higher than the boiling point temperature of the working fluid in the second liquid storage tank CYG2 to ensure that the working fluid of system I can be cooled and liquefied in the countercurrent heat exchanger NLHRQ.

[0098] Heat pump: It consists of a compressor YQJ, a first heat exchanger HR1 arranged at the bottom of the liquid storage tank CYG1, and a refrigeration expansion machine PZ; the air outlet of the second liquid storage tank CYG2, the inlet and outlet of the compressor YQJ, the inlet and outlet of the first heat exchanger HR1, the inlet and outlet of the refrigeration expansion machine PZ, and the inlet of the second liquid storage tank CYG2 are connected in series in sequence, and the compressor YQJ, the refrigeration expansion machine PZ and its driving motor operate coaxially; an exhaust port To LX is arranged on the top of the first liquid storage tank CYG1, and the saturated air (-192℃) generated by the heat of the heat pump in the first liquid storage tank CYG1 is discharged from the exhaust port To LX on the top of the first liquid storage tank CYG1 to the second cold box LX2; the first heat exchanger HR1 is installed at the bottom of the first liquid storage tank CYG1.

[0099] The countercurrent heat exchanger NLHRQ is installed in the first cold box LX1, and the first liquid storage tank CYG1, the second liquid storage tank CYG2, the first liquid pump YB1, the second liquid pump YB2, the compressor YQJ, the refrigeration expander PZ and the expander T are installed in the second cold box LX2. The top of the second cold box LX2 is connected to the bottom of the first cold box LX1.

[0100] The automatic controller KZQ is used to control the power system of the closed dual-working medium cycle of the present invention.

[0101] The products selected for each part of the present invention are as follows:

[0102] The automatic controller KZQ adopts the existing controller.

[0103] The liquefaction temperature of the working fluid selected in the first liquid storage tank CYG1 is lower than the ambient temperature. The liquid storage tank adopts a low-temperature container. Insulation measures need to be taken according to the selected working fluid. A Dewar tank is preferred. The first liquid pump YB1 adopts a low-temperature liquid pump.

[0104] The jet pump SLB has two inlets and one outlet, the two inlets are a liquid inlet and an air suction port, and the gas is sucked by the jet of the liquid working fluid in the jet pump SLB; the heat exchanger HRQ can adopt a heat exchanger with a high-temperature heat source such as a boiler, a burner or a heat storage device, or an open-frame vaporizer OFV with water as a heat source or an intermediate medium vaporizer IFV, or an existing heat exchanger such as an air source heat exchanger, a geothermal source heat exchanger, and a geothermal source heat exchanger; the countercurrent heat exchanger NLHRQ adopts a countercurrent heat exchanger in the air separation industry in the prior art, and has a high-temperature channel and a low-temperature channel. The high-temperature channel is connected to system I and releases heat to the low-temperature channel in the countercurrent heat exchanger NLHRQ. The low-temperature channel absorbs heat for system II. The temperature of the high-temperature channel decreases from top to bottom to liquefy the working fluid, and the low-temperature channel absorbs heat from bottom to top to vaporize the high-pressure liquid working fluid in system II to obtain expansion work. The working fluids in the high-temperature channel and the low-temperature channel flow in the countercurrent heat exchanger in reverse to exchange heat.

[0105] The second liquid storage tank CYG2 stores the working fluid of system II, which is subject to certain pressure fluctuations during operation. It is a low-temperature container and needs to take insulation measures, such as a Dewar tank. In order to enable system II to obtain a higher circulation power, the second liquid pump YB2 needs to provide a higher outlet pressure, which is a low-temperature and high-pressure liquid pump. The second heat exchanger HR2 is arranged in the liquid storage tank I and is connected in series to the outlet of the second liquid pump YB2 to adjust the working fluid temperature of the circulating working fluid of system II before entering the countercurrent heat exchanger NLHRQ to ensure that the working fluid of system I can be liquefied in the countercurrent heat exchanger NLHRQ without solidification. The countercurrent heat exchanger NLHRQ has a high-temperature channel and a low-temperature channel, the high-temperature channel is connected in series to system I, and the low-temperature channel is connected in series to system II. The expander T adopts an expander of existing technologies such as a turbine expander, a screw expander, a centripetal expander, and a cylinder expander.

[0106] The heat exchanger HR1 adopts a condensing heat exchanger. The compressor YQJ extracts saturated gas of the working medium from the second liquid storage tank CYG2, compresses and raises the temperature higher than the temperature of the working medium in the first liquid storage tank CYG1, releases heat through the first heat exchanger HR1, and then flows back to the second liquid storage tank CYG2 after reducing the pressure and temperature and liquefying through the refrigeration expander PZ; the heat pump belongs to the existing technology and will not be described in detail;

[0107] The automatic controller KZQ is used to keep the temperature, pressure, flow and other parameters of each part of the automatic system at the set value. It is easy to implement using the existing technology and will not be described in detail in the present invention.

[0108] The present invention provides a control method for a closed dual-fluid cycle power system, which specifically includes the following operations:

[0109] The first liquid pump YB1 in the automatic control system I extracts a certain amount of liquid working medium from the first liquid storage tank CYG1 and sends it to the jet pump SLB. The jet pump SLB extracts a certain amount of gaseous working medium from the first cold box LX1, and the mixed working medium is sent to the heat exchanger HRQ for heating and gasification to become normal temperature working medium gas. The normal temperature working medium gas then flows into the high temperature channel of the countercurrent heat exchanger NLHRQ, transfers the heat to the low temperature channel of the countercurrent heat exchanger NLHRQ, cools down in the high temperature channel of the countercurrent heat exchanger NLHRQ, and liquefies and flows into the first liquid storage tank CYG1, completing the cycle.

[0110] The second liquid pump YB2 of the automatic control system II extracts liquid working medium from the second liquid storage tank CYG2, sends it through the low-temperature channel of the second heat exchanger HR2 and the countercurrent heat exchanger NLHRQ to absorb heat and gasify into high-pressure steam, and the exhaust steam after expansion and work by the expander T flows into the second liquid storage tank CYG2, completing the cycle;

[0111] The compressor YQJ of the automatic control heat pump extracts the working medium exhaust steam in the second liquid storage tank CYG2, compresses and heats it (to a temperature higher than the temperature of liquid air -192℃, about -170℃), and then flows through the heat exchanger set in the first liquid storage tank CYG1.

[0112] IHR1 transfers the exhaust steam heat to the first liquid storage tank CYG1 and then liquefies through the refrigeration expansion machine PZ and flows back to the second liquid storage tank CYG2;

[0113] The automatic controller KZQ controls the pressure, temperature and flow of each part of the system to run at the preset values.

[0114] Figure 5 It is a PH schematic diagram of the power system of the closed dual working fluid cycle of the present invention, line I is the saturation line of the circulating working fluid of system I, lines 123 are the circulation lines of the working fluid in system I, 1-2 is the pressurization process of liquid pump IYB1 and jet pump SLB, 2-3 is the endothermic process of the working fluid, and 3-1 is the exothermic process of the working fluid; line II is the saturation line of the working fluid of system II, lines 4567 are the circulation lines of the working fluid in system II, 4-5 are the pressurization lines of liquid pump 2, 5-6 are the isobaric heating lines of the working fluid, and 6-7 are the isentropic expansion lines of the working fluid; line III is the circulation line of the heat pump working fluid, 7-8 are the pressurization process of the heat pump compressor, 8-9 are the heat release process of the heat pump system heat exchanger HR to system I, and 9-10 are the isentropic expansion process of the refrigeration expander PZ.

[0115] The closed dual-medium cycle power system of the present invention is equivalent to the semi-open dual-medium cycle power system, which omits the air compressor KYJ, the air filter GLQ and the molecular sieve exchanger JHQ, and adds the first liquid pump YB1, the jet pump SLB and the heat exchanger HRQ in series to form a closed-loop system I; if air is still used as the working medium in the closed system I and hydrogen is used as the working medium in the system II, the difference from the semi-open system is that the first liquid storage tank of the closed dual-medium power cycle system receives the heat input by the heat pump, and the generated air saturated gas needs to be extracted by the jet pump SLB. During operation, the jet pump SLB is automatically controlled according to the amount of air saturated gas generated in the first liquid storage tank. And the liquid pump ⅠYB1 extracts the gas and liquid in the first liquid storage tank CYG1 in a ratio to keep the temperature of the liquid air in the first liquid storage tank CYG1 stable at -192℃; in the closed system Ⅰ, if the air temperature at the outlet of the heat exchanger HRQ is set to 20℃, the hydrogen outlet temperature of the countercurrent heat exchanger NLHRQ can reach 0℃, which can have the same operating effect and system parameters as the example in the semi-open system; similarly, when air and hydrogen are selected as dual working fluids, in order to avoid combustion caused by leakage of hydrogen working fluid, a cylinder expander can be used or other methods that can avoid leakage of hydrogen working fluid can be adopted; if other dual-circulation working fluids are selected, it can be operated according to the above-mentioned control method, and no examples will be given to save space.

[0116] There is still a lot of room for research on the combination of different working fluids in closed dual-fluid cycle power systems. Current research believes that air and hydrogen are used as the working fluids of the dual-fluid cycle system, helium is used as the cooling fluid, and the lowest temperature in the circulation system is liquid helium (4.2K) close to 0k, which maximizes the temperature range of the power cycle. Heat can be drawn from the ambient temperature heat source to drive the power system cycle, and high-temperature heat sources such as boilers can be used to supply heat to the heat exchanger of the closed dual-fluid cycle system. The theoretical thermal efficiency of the system can jump to 1, and the following disruptive changes will also occur.

[0117] In the prior art, the power system with boilers and burners as heat sources aims to continuously increase the temperature of high-temperature heat sources. Various measures have been taken to increase the combustion temperature, which requires huge investment. The higher the temperature, the greater the heat loss of flue gas emissions. For example, the Brayton cycle system of the gas turbine often uses a Rankine cycle of high-temperature flue gas in series with water vapor to reduce flue gas heat loss, but the overall thermal efficiency is only about 50%. Long-term high-temperature combustion is prone to generate NOx, and operating the carbon capture system under high-temperature flue gas emissions greatly reduces the thermal efficiency of the system. The power system with a closed dual-fluid cycle of low-temperature working fluid aims to reduce and recover the heat of exhaust steam in the power system. The closed dual-fluid power cycle system is combined with a boiler or burner. The temperature difference between the low-temperature working fluid and the boiler and burner in the heat exchanger is large, and the heat absorption capacity is strong, so good heat transfer can be obtained without a very high combustion temperature. Liquid air first enters the flue , and then enter the furnace to be heated to the ambient temperature area to obtain a good circulation effect; if the temperature of the power cycle working fluid is too high, it will cause the increase of the condensation heat of the exhaust steam, which is not conducive to the heat recovery of the heat pump. The existing technology believes that the concept of "the higher the temperature, the better" is no longer suitable for the closed dual-working fluid cycle power system of low-temperature working fluid; liquid air at -192℃ absorbs heat and vaporizes in the flue for a long time, which can make the flue gas discharged at a low temperature. The CO2 in the flue gas can be directly formed into dry ice (-78℃) in the flue for recovery, realizing carbon-free emissions, and only emitting low-temperature N2 and other gases, so that the heat loss of flue gas emissions is negative, and the overall thermal energy utilization rate is higher. The low-temperature N2 discharged from the flue can also be used as a cold air source; the closed dual-working fluid cycle power system provides the possibility for environmental energy development, and also provides a new method for burning high-temperature heat sources such as fossil fuels + low-temperature emissions of flue gas as a cold air source + direct carbon capture.

[0118] Preferably, in the closed dual-fluid cycle power system of the present invention, the heat exchanger HRQ is an open-frame gasifier OFV or an intermediate medium vaporizer IFV with water as the heat source in the prior art, or a geothermal source heat exchanger or a geothermal source heat exchanger in the prior art, or an air source heat exchanger with a hydrophobic coating on the surface in the prior art, or a boiler, or a burner, or a heat storage device in the prior art, or a series-parallel combination of the above multiple heat exchangers.

[0119] The open-frame vaporizer OFV and the intermediate medium vaporizer IFV in the prior art are vaporizers used in the low-temperature power generation system with liquefied natural gas LNG as the cold source and seawater as the heat source in the prior art; the air source heat exchanger with a hydrophobic coating on the surface in the prior art can prevent the low-temperature working fluid from passing through the heat exchanger and causing ice on the surface of the heat exchanger; when the boiler or burner of the prior art is used to provide heat energy, the arrangement of the heat exchanger in the boiler and the burner should make the low-temperature section of the heat exchanger be arranged in the flue, so as to promote the low-temperature discharge of the combustion flue gas; the series-parallel combination of the above-mentioned multiple heat exchangers means that the circulation system can be switched between different heat sources in a parallel manner, such as operating the air source heat exchanger and the vaporizer with water as the heat source in parallel, and switching between the two heat sources can be performed according to the season and weather changes; the series mode can be a heat exchanger with environmental energy such as water and air as the heat source followed by a heat exchanger with a boiler or burner or a heat storage device in series. When the ambient temperature is low, a small amount of high-temperature heat source is used to supplement the circulation system so that the entire system can still obtain the best circulation effect.

[0120] Preferably, after the system working fluid is selected, the working fluid output by the second liquid pump YB2 of system II is directly transported to the countercurrent heat exchanger NLHRQ, which will not cause the circulating working fluid of system I to form dry ice in the channel of the countercurrent heat exchanger NLHRQ, and the second heat exchanger HR2 of system II can be omitted.

[0121] Preferably, the heat pump of the closed dual-working-fluid cycle power system is replaced by a heat pump system of the semi-open dual-working-fluid cycle power system.

[0122] That is, a group of evaporators are connected in series between the inlet of the compressor YQJ of the heat pump of the closed dual-working fluid cycle power system and the outlet of the refrigeration expansion machine PZ and are arranged on the top of the second liquid storage tank CYG2, and the refrigeration cycle system selects the third working fluid.

[0123] According to the Carnot cycle theory, it is not easy to reduce the temperature of the low-temperature heat source. The only way is to continuously improve the temperature increase efficiency of the high-temperature heat source, which is also the technical direction that the thermal energy and power major has always adhered to. The scientific significance of the present invention is to create a low-temperature heat source with a very low temperature by integrating the existing technology, and reduce the temperature of the low-temperature heat source by about 200°C from the traditional ambient temperature. In the closed dual-working medium cycle power system proposed by the present invention, the boiler and the burner can be used as high-temperature heat sources, and the heat mass at the ambient temperature can also be used as a high-temperature heat source. Liquid air is a low-temperature heat source, which provides the possibility for the development of environmental energy. The cycle of the heat pump is used to condense the exhaust steam of the power system and recover the heat, so that the theoretical thermal efficiency of the system is equal to 1, which has great progress significance. According to international practice, the dual-working medium cycle power system of the present invention can be named as a long macro cycle; the semi-open dual-working medium cycle power system can be referred to as a semi-open long macro cycle. The closed dual-working medium cycle power system can be referred to as a closed long macro cycle; the theoretical basis of the long macro cycle is: the exhaust steam heat of the power system is controlled to be 0, and the theoretical thermal efficiency of the system is equal to 1.

[0124] The closed long-macro cycle power system can be used for power generation and transportation power. When the ambient temperature heat (water, air, geothermal source, geothermal source, etc.) is used as the heat source, the dual-fluid cycle power system is used to generate electricity, which can achieve zero-carbon, distributed, and free power. An air source heat exchanger with a hydrophobic coating on the surface is installed on the outside of the locomotive and a closed long-macro cycle power system is used, which can enable the locomotive to obtain zero-carbon, free power.

Claims

1. A semi-open dual-medium cycle power system, characterized in that: It consists of an air liquefaction circulation system, a hydrogen working medium power circulation system, a heat pump system and an automatic controller KZQ, a first cold box LX1 and a second cold box LX2; among which: The air liquefaction circulation system is composed of an air filter GLQ, an air compressor KYJ, a molecular sieve exchanger JHQ, a countercurrent heat exchanger NLHRQ, and a first liquid storage tank CYG1; wherein the first liquid storage tank CYG1 is provided with a liquid-air outlet L-Air out, an air supply port To LX to a cold box, and a control valve; the air inlet Air in to the inlet and outlet of the air filter GLQ, to the inlet and outlet of the air compressor KYJ, to the inlet and outlet of the molecular sieve exchanger JHQ, to the inlet and outlet of the high-temperature channel of the countercurrent heat exchanger NLHRQ, and to the inlet of the first liquid storage tank CYG1 are connected in series in sequence; The power circulation system of the hydrogen working medium is composed of a second liquid storage tank CYG2, a liquid pump YB, a heat exchanger HR, and at least one two-stroke cylinder expander QG for air intake, work and compression and exhaust; wherein, the liquid outlet of the second liquid storage tank CYG2 to the low-temperature inlet and outlet of the countercurrent heat exchanger NLHRQ, to the inlet and outlet of the cylinder expander QG, and to the inlet of the second liquid storage tank CYG2 are connected in series in sequence, the liquid pump YB is installed at the liquid outlet of the second liquid storage tank CYG2, the heat exchanger HR is installed in the saturated liquid in the first liquid storage tank CYG1, and is connected in series between the liquid pump YB and the low-temperature inlet of the countercurrent heat exchanger NLHRQ; liquid hydrogen is stored in the second liquid storage tank CYG2; The heat pump system is composed of a compressor YQJ, a refrigeration expansion machine PZ, an evaporator ZF, and a condenser LN; wherein the condenser LN is arranged in the liquid working medium area at the bottom of the first liquid storage tank CYG1, and the evaporator ZF is arranged in the gaseous working medium area at the top of the second liquid storage tank CYG2, and the outlet of the compressor YQJ is connected in series to the inlet and outlet of the condenser LN, to the inlet and outlet of the refrigeration expansion machine PZ, to the inlet and outlet of the evaporator ZF, and to the inlet of the compressor YQJ; the heat pump system is filled with helium as a circulating working medium, and the compressor YQJ, the refrigeration expansion machine PZ and its driving motor are coaxially operated; The countercurrent heat exchanger NLHRQ is installed in the first cold box LX1, and the first liquid storage tank CYG1, the second liquid storage tank CYG2, the liquid pump YB, the compressor YQJ, the refrigeration expansion machine PZ, and the cylinder expansion machine QG are all installed in the second cold box LX2; an outlet To cool for sending cold air to the outside is provided on the top of the first cold box LX1; the top of the second cold box LX2 is connected to the bottom of the first cold box LX1. Automatic controller KZQ is used to automatically control the temperature, pressure, flow and other parameters of each part of the system to maintain them at the set values.

2. A control method for a semi-open dual-medium cycle power system, characterized in that: The power system based on the semi-open dual-working medium cycle of claim 1 specifically includes the following operations: The operation of the air compressor KYJ and the molecular sieve exchanger JHQ in the automatic control system I inhales air from the air inlet Air in, filters impurities in the air through the air filter GLQ, pressurizes through the air compressor KYJ, sends it to the molecular sieve exchanger JHQ to filter moisture and CO2 in the air, enters the high-temperature channel of the countercurrent heat exchanger NLHRQ to release heat and cool to the outlet for liquefaction, and then flows into the first liquid storage tank CYG1; The liquid pump YB of the power circulation system of the hydrogen working medium is automatically controlled, and the liquid hydrogen is extracted from the second liquid storage tank CYG2, pressurized, and then sent to the heat exchanger HR and the countercurrent heat exchanger NLHRQ to absorb heat and gasify into high-pressure normal-temperature steam, and then enter the cylinder expansion machine QG, and the inlet valve and outlet valve of the cylinder expansion machine QG are automatically controlled to make the cylinder expansion machine QG operate between the two strokes of intake work and compression exhaust, and work is performed externally, and the exhaust steam after work is discharged into the second liquid storage tank CYG2; The heat pump system is automatically controlled so that the compressor YQJ compresses the working medium helium filled during the installation process of the heat pump system, and the temperature rises to a temperature exceeding that of the liquid air in the first liquid storage tank CYG1, flows through the condenser LN to release heat to the liquid air, and then passes through the expander PZ to reduce the pressure and temperature to the outlet for liquefaction, and then flows through the evaporator ZF to absorb heat and vaporize, and automatically circulates to bring the exhaust steam heat in the second liquid storage tank CYG2 to the first liquid storage tank CYG1; part of the liquid air in the first liquid storage tank CYG1 is heated and vaporized to become low-temperature cold air, which is successively sent to the second cold box LX2 and the first cold box LX1, and finally sent out as cold air To cool, and the unvaporized liquid air is discharged to the outside from the liquid air outlet L-Air out; Automatic controller KZQ automatically controls the pressure, temperature and flow of each part of the system to run at the preset values.

3. A closed dual-fluid cycle power system, characterized in that: It consists of a high-temperature working fluid circulation system, a low-temperature working fluid circulation system, a set of heat pumps, an automatic controller, a first cold box LX1 and a second cold box LX2; wherein: The high-temperature working medium circulation system is composed of at least one first liquid storage tank CYG1, a first liquid pump YB1, a jet pump SLB, a group of heat exchangers HRQ and a group of countercurrent heat exchangers NLHRQ; wherein the liquid working medium outlet of the first liquid storage tank CYG1 is connected in series to the inlet and outlet of the first liquid pump YB1, to the inlet and outlet of the jet pump SLB, to the inlet and outlet of the heat exchanger HRQ, to the high-temperature channel inlet and outlet of the countercurrent heat exchanger NLHRQ, and to the inlet of the first liquid storage tank CYG1; the air intake of the jet pump SLB is connected to the top exhaust port of the first cold box LX1; The low-temperature working medium circulation system is composed of at least one second liquid storage tank CYG2, a second liquid pump YB2, a second heat exchanger HR2, an expander T and a generator connected thereto; wherein the liquid working medium outlet of the second liquid storage tank CYG2, the inlet and outlet to the second liquid pump YB2, the inlet and outlet of the second heat exchanger HR2, the inlet and outlet to the low-temperature channel of the countercurrent heat exchanger NLHRQ, the inlet and outlet to the expander T, and the inlet to the low-temperature liquid storage tank CYG2 are connected in series in sequence. The second heat exchanger HR2 is installed at the bottom of the first liquid storage tank CYG1; the boiling point temperature of the working medium stored in the first liquid storage tank CYG1 must be higher than the boiling point temperature of the working medium in the second liquid storage tank CYG2; Heat pump: It consists of a compressor YQJ, a first heat exchanger HR1 arranged at the bottom of the liquid storage tank CYG1, and a refrigeration expansion machine PZ; the air outlet of the second liquid storage tank CYG2, the inlet and outlet of the compressor YQJ, the inlet and outlet of the first heat exchanger HR1, the inlet and outlet of the refrigeration expansion machine PZ, and the inlet of the second liquid storage tank CYG2 are connected in series in sequence, and the compressor YQJ, the refrigeration expansion machine PZ and its driving motor operate coaxially; an exhaust port To LX is arranged on the top of the first liquid storage tank CYG1, and the saturated air generated by the heat of the heat pump in the first liquid storage tank CYG1 is discharged from the exhaust port To LX on the top of the first liquid storage tank CYG1 to the second cold box LX2; the first heat exchanger HR1 is installed at the bottom of the first liquid storage tank CYG1. The countercurrent heat exchanger NLHRQ is installed in the first cold box LX1, and the first liquid storage tank CYG1, the second liquid storage tank CYG2, the first liquid pump YB1, the second liquid pump YB2, the compressor YQJ, the refrigeration expander PZ and the expander T are installed in the second cold box LX2. The top of the second cold box LX2 is connected to the bottom of the first cold box LX1. Automatic controller KZQ is used to automatically control the temperature, pressure, flow and other parameters of each part of the system to maintain them at the set values.

4. The closed dual-fluid cycle power system according to claim 3, characterized in that: The heat exchanger HRQ uses a heat exchanger with a high temperature heat source such as a boiler, a burner or a heat storage device, or an open frame vaporizer OFV using water as a heat source or an intermediate medium vaporizer IFV, or an air source heat exchanger, a ground source heat exchanger, or a geothermal source heat exchanger.

5. The closed dual-fluid cycle power system according to claim 3, characterized in that: The expander T is a turbine expander, a screw expander, a centripetal expander or a piston expander.

6. A control method for a closed dual-fluid cycle power system, characterized in that: The closed dual-fluid cycle power system according to any one of claims 3 to 5 specifically includes the following operations: The first liquid pump YB1 in the automatically controlled high-temperature working medium circulation system extracts a certain amount of liquid working medium from the first liquid storage tank CYG1 and sends it to the jet pump SLB. The jet pump SLB extracts a certain amount of gaseous working medium from the first cold box LX1, and sends the mixed working medium to the heat exchanger HRQ for heating and gasification to become normal-temperature working medium gas. The normal-temperature working medium gas then flows into the high-temperature channel of the countercurrent heat exchanger NLHRQ, transfers the heat to the low-temperature channel of the countercurrent heat exchanger NLHRQ, cools down in the high-temperature channel of the countercurrent heat exchanger NLHRQ, and liquefies and flows into the first liquid storage tank CYG1, completing the cycle. The second liquid pump YB2 of the automatic control low-temperature working medium circulation system extracts liquid working medium from the second liquid storage tank CYG2, sends it through the low-temperature channel of the second heat exchanger HR2 and the countercurrent heat exchanger NLHRQ to absorb heat and gasify into high-pressure steam, and the exhaust steam after expansion and work by the expander T flows into the second liquid storage tank CYG2 to complete the cycle; The compressor YQJ of the automatic control heat pump extracts the working medium exhaust steam in the second liquid storage tank CYG2, compresses and heats it, and then flows through the heat exchanger ⅠHR1 arranged in the first liquid storage tank CYG1, transfers the exhaust steam heat to the first liquid storage tank CYG1, and then liquefies through the refrigeration expansion machine PZ and flows back to the second liquid storage tank CYG2; The automatic controller KZQ controls the pressure, temperature and flow of each part of the system to run at the preset values.

7. A closed dual-fluid cycle power system, characterized in that: When the circulating working fluid is selected, in the closed dual-working fluid cycle power system described in any one of claims 3 to 5, the working fluid output by the second liquid pump YB2 of the low-temperature working fluid circulation system is directly transported to the countercurrent heat exchanger NLHRQ without causing the circulating working fluid of the high-temperature working fluid circulation system to form dry ice in the channel of the countercurrent heat exchanger NLHRQ, then the closed dual-working fluid cycle power system does not include the heat exchanger HR2.

8. A closed dual-fluid cycle power system, characterized in that: The system is obtained by replacing the heat pump in the closed dual-fluid cycle power system described in any one of claims 3 to 5 with the heat pump system of the semi-open dual-fluid cycle power system described in claim 1.

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