Air-water thermal power plant

Abstract

A thermal power plant includes at least one expander system, an energy supply fluid, an energy receiving fluid, and a direct contact heat and mass transfer exchanger that facilitates heat and mass transfer from the energy supply fluid to the energy receiving fluid for expansion in the expander to produce electrical power. The energy supply fluid may include water and be present in one of the following states: a liquid, a liquid-vapor two-phase mixture, and superheated steam; the energy receiving fluid may include one of air, steam, an air-steam mixture, and an air-steam-liquid mixture. The power plant may further include at least one regenerator and recover energy and moisture contained in the energy receiving fluid discharged from the expander.

Description

[0001] This application is a continuation-in-part of U.S. Provisional Patent Application 63 / 353,606, which was filed on June 19, 2022. Field of the Invention

[0002] The present invention relates to a thermal power plant using air and water as working fluids. Specifically, the present invention facilitates the use of relatively low temperature renewable energy heat sources to generate electricity and provide thermal energy for heat consumers. Background of the Invention

[0004] Thermal power plants that can generate electricity on a utility scale using large amounts of low- or medium-temperature thermal energy resources could have a significant impact on the development of renewable energy. Cao (2022a) demonstrated utility-scale underground hot water storage facilities based on renewable energy that have the potential to replace more than 80% of the fossil fuels currently used worldwide. However, the economic viability of these storage systems is very sensitive to their temperature and pressure, and studies have shown that an ideal temperature range is close to or slightly above 100°C, more specifically in the medium-low temperature range between 90 and 150°C. If the water temperature is significantly above this range, the cost of the hot water storage system may increase exponentially. In addition, the process of obtaining water heat through solar collectors prefers lower temperatures. When the temperature of solar collectors increases, their efficiency may drop from about 75% to less than 40%. For higher temperatures above 180°C, concentrated solar collectors may be required, which not only significantly increases the cost of solar energy acquisition, but also fails to collect the diffuse portion of solar radiation, which typically accounts for 25% to 50%.

[0005] Thermal power stations that can generate electricity at lower temperature ranges are equally critical in geothermal power generation. According to the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE), geothermal resources below 300°F (149°C) are among the most common geothermal resources. One of the biggest challenges facing geothermal exploration is the high cost of deep well drilling required to access higher heat source temperatures, which typically requires extensive drilling at depths of 3,000 to 5,000 meters, depending on the project geology. As geothermal drilling depths increase, drilling costs will increase exponentially, which may make the project economically unfeasible.

[0006] Conventional power plants based on steam turbines are commonly used in coal-fired steam power plants and nuclear power plants, and may also be candidates for solar and geothermal applications. Steam turbine power plants have been used to generate electricity from dry steam from geysers. However, according to the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE), the most common geothermal power application is a flash steam power plant, which is limited to cases where the heat source temperature is above 360°F (182°C). Therefore, for heat source temperatures below 200°C, binary cycle geothermal power plants become the main choice. In a binary cycle-based geothermal power plant, the heat of the geothermal fluid is transferred to a second fluid (EERE) with a lower boiling point than water through a heat exchanger. The most common second fluids include isobutane, pentane, or ammonia. Under highly pressurized conditions, these fluids extract heat from the geothermal fluid by evaporation. The steam generated in the heat exchanger is directed to an expander to generate electricity. The second fluid discharged from the expander is condensed through a closed-loop condenser and returned to the geothermal fluid heat exchanger to complete the cycle. This design can result in high costs due to the high pressure and closed-loop system. Additionally, isobutane, pentane and ammonia are all highly hazardous substances. While acceptable in small-scale applications, in large-scale applications, the risk of leakage of these fluids under highly pressurized conditions can have significant health and environmental impacts.

[0007] Refrigerants such as R-134a, R-123, and R245fa are common working fluids in many other Organic Rankine Cycle (ORC) systems. However, refrigerants typically have very low specific vapor volumes (or high vapor densities). Since the power output of a turbine is proportional to the product of the specific vapor volume and the pressure drop, the power output per unit mass flow rate will be very limited at a given pressure drop. As a result, ORC power plants using refrigerants as working fluids typically have low power capacities and cannot meet the needs of utility-scale power generation. SUMMARY OF THE INVENTION

[0009] Air and water are the most important natural fluids on Earth, and their interaction with each other and with soil and other natural resources sustains life on Earth. Since the Industrial Revolution more than 250 years ago, they have also become working fluids in power plants and engines. Water is the working fluid in steam engines and steam power plants burning fossil fuels, as well as nuclear power plants, while air is the working fluid in internal combustion engines (ICs), aircraft engines, and industrial gas turbine power plants. From the perspective of the core thermodynamic cycle, air is the only working fluid in IC engines and gas turbine power plants, while water is excluded. On the other hand, water is the working fluid in steam engines and steam power plants, while air is excluded. For example, in a steam engine or steam power plant, any meaningful accumulation of air is intolerable and must be removed by a vacuum pump system. However, from a philosophical point of view, similar to the relationship between positive and negative charges, air and water can be seen as a pair of "mates", one is a "positive fluid" and the other is a "negative fluid", and vice versa. Their close interaction is essential for life and ecosystems on Earth. For example, their interaction contributes to the water cycle in meteorology and has important implications for climate systems and ecosystems. It is believed that their interaction could also enable the development of a new type of power plant by harnessing renewable energy and operating at sufficiently low temperatures to enable utility-scale electricity production without the use of hazardous working fluids.

[0010] Therefore, one of the main objects of the present invention is to provide an air-water power plant that operates at relatively low temperatures, does not require combustion but is capable of producing utility-scale electricity at high second law efficiency. The air-water power plant uses both air and water as working fluids and employs direct contact mass and heat exchangers (or packing) to achieve latent heat transfer (mass transfer in the form of steam) and sensible heat transfer from hot water carrying heat to air to produce a steam and air mixture for expansion of an expander to generate electricity, wherein the direct contact nature of mass and heat transfer within the packing enables the use of relatively low temperature hot water as a heat source to produce electricity. Another main object of the present invention is to recover heat and water from the steam-air mixture discharged from the expander through a regenerator condenser, wherein cold water from the packing is directed to the regenerator to recover heat and water from the expanded steam-air mixture to improve the thermal efficiency of the power plant and reduce water losses. Yet another main object of the present invention is to employ a vacuum pump compression system to maintain the pressure at the expander outlet at a level below ambient pressure, thereby increasing the expansion ratio of the expander and discharging the exhaust gas. Another object of the present invention is to use a cooler to cool the power plant inlet air flow, the air flow before the compression system or the air flow within the compressor intercooler to reduce the energy consumption of the compression system or enable the power plant to operate under high ambient temperature and low heat source temperature conditions.

[0011] BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic vertical cross-sectional view of an air-water power plant device, in which a direct contact mass-heat exchanger (packing) is used as a means of energy extraction of the working fluid before turbine expansion, drawn according to an embodiment of the present invention.

[0013] Figure 2 is a conceptual diagram of the flow pattern in a local area of ​​a direct contact mass-heat exchanger (packing);

[0014] Figure 3 yes Figure 1 a schematic cross-sectional view of the water collection system shown;

[0015] Figure 4 It is a demonstration Figure 1 A flow chart showing the operating principle of the power plant shown, including the water or heat recovery unit;

[0016] Figure 5a for Figure 1 ts diagram of the thermodynamic cycle of an air-steam mixture in the power plant shown, with certain idealized assumptions;

[0017] Figure 5b For Figure 1 The thermodynamic cycle of water associated with the operation of the power plant shown is represented by the water temperature t w The ratio of water flow to dry air flow wa Relationship diagram;

[0018] Figure 6 is a schematic diagram of a chiller system for cooling the air of an intercooler of a compressor system;

[0019] Figure 7 is a schematic vertical cross-sectional view of an air-water power plant employing a vacuum pump compression system for maintaining turbine back pressure below ambient pressure and exhausting exhaust gases;

[0020] Figure 8a It is a demonstration Figure 7 A flow chart showing the operating principle of the power plant shown;

[0021] Figure 8b Shows along Figure 7 The pressure distribution at the power plant height shown;

[0022] Fig. 9 is a flow diagram of an air-water power plant with a separate flash chamber;

[0023] Fig.10 A flow chart of an air-water power plant including a front-end compression system and a rear-end vacuum pump compression system;

[0024] Fig.11 is a flow chart of an air-water power plant including a reheating mechanism;

[0025] Fig.12 is a flow chart of an air-water power plant using steam as the energy supply fluid and removing the direct contact mass-heat exchanger (packing) system;

[0026] Fig.13 is a schematic vertical cross-sectional view of an air-water power plant unit using an internal cooling mechanism (such as water mist cooling) for cooling the compressor system.

[0027] Detailed description of the invention

[0028] In the air-water power plant disclosed in the present invention, air or an air-steam mixture is a fluid that receives energy, and hot water is an energy supply fluid, and power generation is achieved through an expander (such as a turbine). The hot water is preferably a liquid, but it can also be a liquid-steam two-phase mixture or superheated steam. The energy acquisition of the working fluid can be in the form of latent heat: by evaporating the hot water and generating steam in a direct contact heat and mass exchanger or packing, the steam enters the air or air-steam mixture flow. The steam and air generate power in an expander (such as a turbine). Since the latent heat of steam is very high, about 2200 kJ / kg, even if the sensible heat acquisition may be limited, the total energy acquired may still be very high to generate sufficient power. Since the flow rate of dry air may remain basically constant throughout the packing and the turbine, the work capacity of the turbine and the steam content in the air-steam mixture entering the turbine can be measured on a per kilogram basis of dry air. The parameter used to measure the steam content or latent heat level in moist air or air-steam mixtures (or steam-air mixtures) is the humidity ratio (or specific humidity) W, expressed in kg of steam per kg of dry air. The enthalpy of the air-steam mixture at the turbine inlet, expressed in kilojoules (kJ) per kg of dry air, can be approximated by the following relationship (McQuiston, 2005):

[0029] h i =c pa ×t+W×(h fg +c pv ×t) (1)

[0031] Where t is the temperature in degrees Celsius (℃), c pa is the specific heat of dry air, h fg is the latent heat of vaporization of water at 0°C, c pvis the corresponding steam specific heat. It is well known that in thermal power plants, the enthalpy of the working fluid at the turbine inlet may determine the power generation capacity of the turbine under given turbine outlet conditions (Moran et al., 2011). After ignoring the influence of the kinetic energy and potential energy of the turbine working fluid and the heat dissipation effect of the turbine, it is shown in the following equation (2):

[0032] w t =h i -h o (2)

[0034] Among them, w t is the work produced by the turbine, h i is the enthalpy at the turbine inlet, h o is the enthalpy at the turbine outlet. For the air-water power plant disclosed in the present invention, for convenience, all three terms in equation (2) are in kilojoules per kilogram of dry air (kJ / kg). The inlet enthalpy in equation (1) represents the total energy content of the air-steam mixture, which subsequently determines the power generation capacity of the power plant. Obviously, it can be seen from equation (1) that the total enthalpy is mainly determined by the humidity ratio W, because the first term on the right side of equation (1) represents the sensible heat of the dry air, which is relatively small for low-temperature power plants. In contrast, for conventional fossil fuel-based gas turbine power plants, the second term on the right side of equation (1) is essentially close to zero, and the turbine inlet enthalpy is contributed by the sensible heat represented by the first term. In this case, the temperature in the first term may typically need to reach more than 1500°C by burning fossil fuels to obtain sufficient sensible heat for the production of high turbine power.

[0035] Referring to equation (1), under given thermodynamic conditions, the saturation humidity ratio represents the maximum amount of steam that the air-steam mixture can hold, which will determine the maximum heat content of the mixture at the turbine inlet and the maximum power capacity of the turbine at given turbine inlet temperature and outlet conditions. Since the mixture temperature at the turbine inlet may be close to the temperature of the hot water entering the power plant, the saturation humidity ratio at the turbine inlet can also represent the potential of the power plant at a given heat source temperature.

[0036] The following relationship can be used to calculate the saturation humidity ratio (McQuiston, 2005; Moran et al., 2011) with sufficiently high accuracy:

[0037]

[0038] Among them, p sis the saturated vapor pressure corresponding to the temperature of the air-vapor mixture, and P is the total pressure or system pressure of the mixture. Table 1 shows the saturated humidity ratio, latent heat content, sensible heat content, and latent heat fraction for certain air-water mixture conditions (based on temperature and total pressure), where the latent heat content is defined as the heat energy associated with the vapor component.

[0039] Table 1: Latent heat potential of air-steam mixtures at given temperatures and total pressures

[0040]

[0041] As shown in Table 1, the latent heat content of the air-steam mixture increases exponentially as the temperature increases from 86.9°C to 126°C. At a temperature of 116.2°C, the latent heat content of the mixture accounts for more than 97%, while the contribution of sensible heat is negligible. The results in the table also show that although the operating temperature has a dominant effect on the saturated humidity ratio, lower system pressure or total pressure can significantly increase the humidity ratio. For example, at a temperature of 96.6°C and a total pressure of 1.01 bar, the value of the saturated humidity ratio is about 4.91, which is much higher than the value at a temperature of 126°C and a higher total pressure of 3.03 bar. Table 1 also shows an example of a cooling tower application with a terminal temperature of 40°C. In cooling tower applications, the only goal is to cool the water to near ambient temperature by evaporating it into the air, and the state of the air inside the tower is not the focus of the operation. Although the amount of latent heat content in the wet air is relatively small due to the low temperature, it still accounts for more than 75% of the total energy content of the wet air.

[0042] Since the gas turbine cycle has the advantages of an open cycle, a simpler structure, and a fast start-up compared to the steam power cycle, the gas turbine power platform is used in the first embodiment of the air-water power plant. Figure 1 Schematically illustrates an air-water power plant arrangement based on an axial turbine or compressor, having a generally circular cross-section, and using hot water as the energy supply fluid. Figure 1 , starting from the bottom of the power plant, the ambient wet air 10 at a temperature t o and humidity ratio W o and pressure p amThe air 10 is introduced into the power plant through an air inlet portion 12 equipped with louvers. The air 10 converges and flows upward to the inlet of the first compressor 16 of the compressor system. In order to prevent liquid or solid particles from entering the compressor, a drift eliminator 18 can be installed in front of the compressor inlet. As shown in the figure, an inlet protection cover 20 can be set around the shell 22 of the power plant to play a similar protective role, especially in stormy or snowy weather conditions. If the combined function of the inlet protection cover and the louvers can effectively prevent liquid or solid particles from entering the compressor, the drift eliminator 18 at the compressor inlet may not be required.

[0043] Airflow 10 enters a first compressor 16 of a compressor system, which may include two compressors and an intercooler 24, and is compressed to a higher pressure and temperature. The air then flows through the intercooler 24 and may be cooled back to a temperature close to that at which it entered the first compressor 16. Figure 1 As shown, cooling water 26 enters from the upper part of the intercooler and flows out from the lower part. Since air-water power plants have the advantage of low temperature operation, it is crucial to fully cool the air and maintain a low temperature at the outlet of the compressor system. The intercooler can also reduce the power consumption of the compressor and improve the energy recovery efficiency in the subsequent regenerator (which will be described in detail later in this disclosure). The intercooler can be any suitable type of heat exchanger, including countercurrent and cross-flow types, but a specific microchannel heat exchanger may be more advantageous in this application and can be used to reduce the air temperature and reduce the pressure drop of the intercooler. Alternatively, a direct contact heat exchanger can also be used as an intercooler (not shown). The air cooled by the intercooler continues its flow path and enters the second compressor 30. The air flow 32 is further compressed in the second compressor 30 to a higher pressure p c , temperature t2 and humidity ratio W o , as shown on the left side of the figure. Figure 1 Only one intercooler and two compressors are shown, but multiple intercoolers and more than two compressors may be installed (not shown).

[0044] After leaving the compressor system, the compressed air 32 enters the packing 34, which obtains latent heat and sensible heat from the counter-flowing hot water 36 to increase its steam content and temperature, thereby essentially transforming into a steam-air mixture 38. The packing, filling, or packed bed here is a direct contact heat and mass exchanger for transferring heat and mass between hot water and a steam-air mixture. In this disclosure, "humid air" and "air-steam (or steam-air) mixture" are used interchangeably. However, the term "humid air" may mean that the steam content in the air is relatively small, while "air / steam" or "steam / air mixture" may mean that the steam content in the mixture is relatively high. Through the close contact between the downwardly flowing hot water 36 and the upwardly flowing cooler steam-air mixture 38, a combined mass and heat transfer occurs at the interface between the hot water and the steam-air mixture. Since the steam partial pressure at the interface is higher than the steam partial pressure in the steam-air mixture, the hot water vaporizes at the interface and enters the steam-air mixture flow. Packing is essentially a system of baffles designed to slow the flow of hot water and maximize the contact between the hot water droplets and the steam-air mixture (Hill et al., 1990). In addition, it increases the contact area between the hot water film and the steam-air mixture while minimizing the thickness of the hot water film. Another packing design goal is to minimize the pressure drop of the steam-air mixture as it passes through the packing layer. Figure 2 is a conceptual diagram of the flow pattern within a localized area of ​​the packing, showing the upwardly flowing air-steam mixture 38, the downwardly flowing hot water film 36, the mass flux of steam from the liquid-steam interface into the steam-air mixture, and the solid matrix of the packing. However, the sensible heat transfer from the liquid film to the steam-air mixture, which would cause the temperature of the steam-air mixture to increase from the bottom to the top of the packing, is not shown in the figure. It should be emphasized that this conceptual diagram may not reflect the actual configuration of the flow channels and the solid matrix of the packing, which may appear complex, tortuous, and random to enhance the intensity of mass and heat transfer.

[0045] Packing (direct contact heat and mass exchanger, packing) and its theory and application in cooling towers have been described in detail by Hill et al. (1990), Hewitt et al. (1994) and other scholars. The packing used in the air-water power plant disclosed in the present disclosure may be configured similarly to the packing in the cooling tower used for power and air conditioning systems, but its purpose is different. In cooling tower applications, the purpose of using packing is to reduce the temperature of the water flow as much as possible so that it can be used as cooler cooling water for power plant condensers or air conditioning (A / C) applications (McQuiston, 2005 and Moran et al., 2011), and the thermal state of the wet air discharged into the environment is not the focus of attention. On the other hand, the application goal of the present invention is to increase the energy content of the air-steam mixture by packing, which is specifically manifested as an increase in its steam content and temperature, so that the energy content of the mixture can be used to generate electricity through a turbine or other expansion device.

[0046] Reference again Figure 1 After acquiring energy in the packing (direct contact heat and mass exchanger, packing) 34, the air-steam mixture 38 is discharged from the packing 34 with an increased humidity ratio and temperature, W1 and t1, as Figure 1 After the liquid droplets are removed by the de-liquidator 40, the air-steam mixture 38 is directed to the turbine 42 to generate power through expansion. Figure 1 In the schematic diagram of FIG. 4 , the turbine, compressor and generator may be connected via a shaft / drum. Part of the power generated by the turbine 42 is used to drive the compressor system (16 and 30), and the remaining power can be used to generate electrical energy through the generator 46, such as Figure 1 The bottom is shown. Starting equipment and other necessary systems may also be installed but are not shown. After converting part of the heat energy into power during the expansion process, the air-steam mixture 48 is discharged from the turbine at a pressure of p b , temperature t e and humidity ratio W e Both decreased, among which p b is the turbine outlet pressure or back pressure, e.g. Figure 1 As shown. However, the air-steam mixture discharged from the turbine may still contain a large amount of unused heat energy and water, especially the steam content in the mixture. If it is discharged directly into the environment, it will seriously affect the thermal efficiency of the power plant and cause significant water losses. Therefore, a regeneration condenser 50 is used to recover a large amount of energy and water from the mixture, and the air-steam mixture 48 will continue to flow into the regeneration condenser 50. However, before completing the description of the air-steam mixture process, let us turn our attention to hot water as the energy supply fluid of the power plant unit.

[0047] refer to Figure 1The middle packing 34, hot water 52 as the heat source fluid, at a temperature t w The hot water 52 enters the power plant through a hot water distribution system 54 at the top of the packing. The hot water 52 can come from a storage system or directly from a heat source. The heat source can include, but is not limited to, solar energy, geothermal energy, industrial waste heat, or fossil fuel-related heat generated by combustion or nuclear reactions. Since the dry air mass from the inlet to the outlet of the power plant is generally constant, similar to cooling towers, the power plant analysis here is based on per unit dry air mass. The inlet flow rate of hot water is expressed in water mass per kg of dry air. As shown in the figure. Since part of the liquid may be vaporized into steam during the process of passing through the hot water distribution system 54, the actual temperature of the hot water 36 entering the packing 34 from the top is t w1 , as shown on the left side of the power plant. The corresponding mass flow rate is Although sometimes the flow into the power plant is also marked as r wa1 By heat and mass transfer in the packing and the countercurrent arrangement, the hot water 36 can transfer its significant thermal energy to the air-steam mixture, accompanied by a significant drop in water temperature. The reduced temperature water 56, at t w2 temperature and lower mass flow rate r wa2 , discharged from the bottom of the packing. Note that r wa2 Less than r wa1 , because part of the water is vaporized in the packing, the resulting steam joins the upward flowing air-steam mixture.

[0048] The cooler water 56 flowing from the fill is collected by a collection system 58 which includes an array of longitudinal collectors which may have a pan or bow-shaped cross section, and a peripheral water tank 60. The collection system 58 extends radially outward from the central area of ​​the power plant and slopes downward to the power plant shell to drive the water to the peripheral water tank 60 by gravity. A cross-sectional view of the collection arrangement is shown in FIG. Figure 3 See Figure 3 A plurality of annularly arranged collecting elements 62 having a pan or arcuate cross-section are staggered along the water flow direction 56 to capture and collect water flowing out of the filler. The width of the collecting elements may also increase with increasing radius due to the increase in circumference resulting from the increase in radius. The arrangement of the collecting elements 62 is also intended to reduce the pressure loss of the humid air 32 as it passes through the collector array and enters the filler 34.

[0049] As mentioned earlier in this disclosure, the water stream 56 flows from the packing 34 and is collected by the collection system 58, and its temperature and associated energy content may be significantly reduced due to mass and heat transfer in the packing. This water can be pumped directly from the peripheral water tank 60 to the storage system for thermal energy recharge, or directly to a heat source, such as a solar collector or other heat source for reheating. However, if the water is pumped from the water tank 60 to the regenerator 50 to recover significant energy and moisture in the air-steam mixture 48 flowing from the turbine 42, a significant amount of energy and water resources can be saved.

[0050] like Figure 1 As shown in FIG. 1 , the regenerator 50 located near the top of the power plant can be a countercurrent direct contact condenser with a packed bed or packing, wherein the cooler water 56 flowing out of the packing 34 can be pumped from the water tank 60 to the water distribution system 62 at the top of the regenerator 50 through the peripheral water tank 64. The packed bed 50 creates an intimate contact between the cooler downflowing water and the hotter rising air-steam mixture 48, which flows out of the turbine and enters the regenerator 50 from the bottom of the packed bed, thereby effectively condensing the steam in the air-steam mixture 48 and heating the water by the heat released by condensation. The condensed water will join the downflowing water flow, thereby increasing the water flow from the top to the bottom of the regenerator. Compared with a conventional non-direct contact condenser with a wall separating the steam and cooling water flows, a direct contact condenser with a packed bed can significantly improve the condensing efficiency due to the greatly increased condensation surface area between the steam and the cooling water and the minimized thermal resistance between the steam and the cooling water. Direct contact condensers can condense almost all of the steam within a very limited packing height, and the final outlet temperature of the water will depend on the energy balance between the inlet steam flow conditions and the inlet water flow conditions (Hewitt et al., 1994). When the total energy content of the inlet steam flow is higher than the maximum energy absorption potential of the inlet water flow, the outlet temperature of the water at the bottom of the packed bed may be very close to the inlet steam temperature.

[0051] Referring again to the regenerator 50, after a large amount of energy and water has been recovered from the air-steam mixture by the regenerator, the temperature is raised to t wr And the flow rate is r war The water 66 is discharged from the regenerator 50 and collected by a water collection system 68 similar to the fill 34. The collected water 66 can be pumped by the water collection system 68 to a storage facility (not shown) or directly to a heat source for thermal energy recharge (not shown). The heat source may include, but is not limited to, solar energy, geothermal energy, industrial waste heat, or fossil fuel related heat generated by combustion or nuclear reactions. The flow rate of water flowing out of the regenerator may be different from the flow rate of hot water 52 entering the fill before the turbine. However, if Figure 1As shown near the top of the power plant, some make-up water 70 can be added to the top of the regenerator. Therefore, the water flow rate r for each kg of dry air leaving the plant is war The hot water flow rate r entering the power plant can be approached wa1 , to meet the needs of thermal power plant cycles.

[0052] On the air-steam mixture side, the mixture is at a temperature t e and humidity ratio W e Entering the regenerator 50 from the bottom of the regenerator condenser, and at a significantly reduced temperature t r and humidity ratio W r After passing through the drift eliminator 72, the air-steam stream 74 from the regenerator is discharged to the environment as exhaust gas. However, the exhaust gas may still contain a large amount of water vapor and heat, so a water or heat recovery device can be added to recover as much water or heat as possible before the exhaust gas stream is discharged to the environment. Figure 1 The primary emphasis is on the power generation process, so water or heat recovery devices are not included in the figure but will be discussed in subsequent sections of this disclosure.

[0053] To further illustrate the Figure 1 The air-water power device shown in the flowchart of its operating principle is Figure 4 where a water or heat recovery unit is added after the regenerator condenser. Water or heat recovery opens the door to dual utilization of electricity and heat, as the recovered water and heat can be used for a variety of purposes, such as but not limited to domestic hot water, domestic heating, and industrial uses. In many cases, an open-cycle power plant may be preferred. However, this does not exclude the operation of a closed-cycle power plant. In addition, thermodynamic cycle analysis is usually based on the concept of a closed cycle, even if the actual operation is based on an open cycle. For these reasons, Figure 4 The operation shown can be considered as a closed cycle. As shown by the dashed line in the figure, after further removing some of the moisture and reducing the temperature, the exhaust gas flow can be returned to the inlet of the compressor system as ambient air. It should also be mentioned that in many practical situations, Figure 4 A water or heat recovery unit can be combined with the regenerator condenser.

[0054] In an air-water power plant, both air and water are the core components of the working fluid, and therefore, the thermodynamic cycle of the air-steam mixture and hot water is used to illustrate the working principle of the power plant. Figure 5aThe thermodynamic cycle of the air-steam mixture is shown in the form of a temperature-entropy (ts) diagram, with certain idealizations. As mentioned earlier, the mass flow of dry air through the power plant usually remains constant, so it is convenient to illustrate the cycle based on the mass of air-steam mixture per kilogram of dry air. At the inlet of the compressor system, which may include at least one intercooler, the temperature of the ambient wet air is t o , the mass of steam in the ambient air is W o (humidity ratio), pressure is p am Based on the weight of each kilogram of dry air, the total mass of ambient air is 1+W o Through the compressor system, the moist air is compressed to a higher pressure p c , a certain amount of mechanical work w needs to be input com The compressed moist air has a temperature of t2 and a mass of 1+W. o Leaving the compressor system, it enters the direct contact packing (heat and mass exchanger), where the humid air simultaneously receives steam and heat from the hot water stream. The air-steam mixture leaves the packing at a higher temperature and humidity ratio, t1, W1, and at a pressure of p t , which may be close to p c , because the pressure drop in packing is usually small. Based on the amount of steam added to the air-steam mixture per kg of dry air is W1-W o ,like Figure 5a The air-steam mixture then enters a turbine or other type of expander, producing a certain amount of shaft work w tur and at reduced temperature and pressure t e , p b Leaves the turbine. Due to the possible condensation of some steam during the expansion process in the turbine, the steam content W e The air-steam mixture further reduces its energy in the condensing regenerator, where its steam content is significantly reduced by steam mass condensation and heat transfer with cooler water entering the regenerator from the packing outlet. At the regenerator outlet, the steam content of the air-steam mixture is reduced to W r , the temperature drops to t r In reality, an air-steam power plant may be an open-loop system, where the air-steam mixture from the regenerator is discharged to the environment. However, as in many other thermodynamic cycle analyses, it can be modeled as a closed-loop system. Therefore, a constant pressure process is added to further remove the steam mass and heat, and the wet air returns to the starting point of the cycle to complete the cycle. In this process, a portion of the steam mass W in the wet air is r -W o Leave and enter the ambient air, such as Figure 5a It should be noted that Figure 4 As shown, a possible water recovery device can be added so that most of the steam water discharged from the regenerator is recovered and not lost to the environment.

[0055] Figure 5b The idealized form of the thermodynamic cycle of water associated with the operation of a power plant is shown in Figure 2. w R wa (water temperature versus dimensionless water velocity) where r wa is the water flow rate Dry air flow rate It should be noted that t w and r wa Here, they are used to indicate the water temperature and flow rate that vary in general, not necessarily Figure 1 The temperature and flow rate of hot water entering the power plant are shown in Figure 1 Also marked as t w and r wa Hot water from a hot water storage facility or heat source at a temperature t w1 and flow rate r wa1 Enter the direct contact heat and mass transfer packing. It should also be mentioned that if the flash evaporation process in the water distribution system is ignored, t w1 and r wa1 The hot water transfers heat and water vapor to the air-steam mixture through mass and heat transfer in the packing, and the water leaves the packing at a reduced temperature and flow rate, respectively t w2 and r wa2 The mass of water removed during packing is wa1 -r wa2 Already in Figure 5b The cooler water then enters the condenser regenerator, where the steam in the hotter air-steam mixture condenses, releasing its heat of condensation. The water absorbs the released heat of condensation, raising its temperature to t wr , which may be close to Figure 5a t in e At the same time, the water absorbs the condensation mass associated with the condensation of the steam and its flow rate increases to r war Therefore, at the regenerator outlet, the water temperature and flow rate both increase, and by adding make-up water, the water will likely be restored to its initial mass r wa1 , that is, r war =r wa1 Obviously, this is an ideal condition for a better description of the cycle. The mass of water added to the regenerator is wa -r wa2 Also in Figure 5b The water leaving the regenerator is then thermally charged by a heat source, raising its temperature to t wa1 , and then returns to packing to complete the loop.

[0056] As is well known, for conventional closed-loop steam power plants (including nuclear power plants), a large amount of external cooling water is required to condense the steam in the condenser. Another significant advantage of the air-water power plant of the present invention is that it utilizes the heat from the filler (e.g. Figure 1 The cold water flowing out of 56) is used to condense the steam in the regenerator condenser to recover heat and water, thereby greatly reducing the need for additional cooling water.

[0057] exist Figure 1 In the illustrated embodiment and cycle analysis, liquid hot water (e.g. Figure 1 52) is mainly used as a heat source supply fluid for power plants. However, superheated steam or a liquid-steam two-phase mixture can also be used as a heat source supply fluid for power plants. In the case of a liquid-steam two-phase mixture, the steam in the mixture entering the power plant can bypass Figure 1 The filler 34 in the mixture flows directly to the turbine (not shown), while the liquid in the mixture enters the filler 34.

[0058] The potential performance of the above-mentioned air-hydrodynamic device was evaluated by model calculation, and some key results are summarized in Table 2 (Cao, 2022b), although the details of the modeling are not included in this disclosure. For all the results in the table, the ambient temperature is set to t o =15°C, and the isentropic efficiencies of the compressor and turbine systems are set to 90% and 95%, respectively.

[0059] Table 2: Figure 1 Some typical operating performance results of the power plant at t0 = 15°C are shown.

[0060]

[0061] The above results are based on the hot water inlet temperature of the power plant t w and the compression ratio of the compressor system. Figure 1 The device diameter D shown is set to 6 meters, and the dry air flow rate at the measurement D position is 10 meters per second. The results also involve the use of two intercoolers in the compressor system. The second law efficiency is defined as the ratio of the thermal efficiency listed in the above table to the corresponding Carnot cycle efficiency. The above results show that the power capacity of the air-water power plant may reach 100 megawatts when the hot water inlet temperature is above 100°C, which is competitive with traditional fossil fuel power plants. Under low temperature operating conditions, its thermal efficiency can also approach or reach 15%, which is a considerable performance.

[0062] The performance results show that the hot water temperature t w is a decisive factor. Figure 1 As shown, with t w As the saturation pressure increases at higher temperatures, the power output and thermal efficiency increase exponentially. However, these improvements are not without cost. Due to the increase in saturation pressure at higher temperatures, the compression ratio may need to be increased accordingly to accommodate the higher operating pressure of the air-steam mixture. Higher pressures may lead to higher costs for the compressor and turbine systems and limit the size of the power plant (such as diameter D), thereby limiting the power capacity. To avoid higher operating pressures, a water flashing mechanism can be used. For example, if the hot water inlet temperature is about t w =150℃, which corresponds to a saturation pressure of about 4.80 bar. If the operating pressure of the packing is set at about 3.0 bar, the pressure of the hot water entering the packing can be reduced from about 5 bar to about 3.0 bar through the nozzle outlet of the water distribution system 54, accompanied by a flash evaporation process. In this process, a portion of the water entering the distribution system 54 will be at a reduced temperature t w1 =134.0℃ flashes to steam. The steam produced by flashing will flow to the turbine and mix with the air-steam mixture flowing out of the packing, while the remaining liquid water after flashing will enter the packing from the top of the packing. In this case, the performance of the power plant may not reach the potential level associated with 150℃, but its power capacity may be significantly improved compared to the case where the power plant inlet hot water temperature is 130℃.

[0063] In the above calculations, the ambient air temperature was set to 15°C, which is an industry standard temperature in thermal power plant evaluations. This temperature may be appropriate for winter or year-round average conditions; however, in the summer, the average ambient temperature should be much higher than this value. Even for some traditional fossil fuel power plants based on steam turbines, higher ambient temperatures can affect their performance. However, for the low operating temperature air-water power plant of the present invention, the impact of higher ambient temperatures on its performance will be more severe. To alleviate this problem, a technique can be used to cool the air at the power plant intake, the compressor system intake, or the intercooler to a level below the ambient temperature. Figure 6 The schematic diagram shows the cooling process of the intercooler air by the cooler. In order to quantitatively demonstrate the effectiveness of this technology, the results of Table 2 are used as a comparative benchmark. In this case, a centrifugal cooler is used to cool the air of the second intercooler, when the ambient temperature and relative humidity increase to t0 = 35 ° C and W respectively. o = 0.018 (steam / dry air), which may represent summer weather conditions. As with other refrigeration systems, the performance of a chiller is measured by its coefficient of performance (COP), which is defined by the following relationship:

[0064]

[0065] In order to reduce the power consumption of the cooler, Figure 6 The intercooler shown is divided into two parts. The lower part uses water from the cooling tower to cool the air to a temperature close to the ambient temperature of 35°C, and then leads the air into the upper part of the intercooler. It should be noted that Figure 6 The cooling tower in the intercooler can be replaced by a dry cooling system to save water resources. For comparison, in the second part of the intercooler, the cooler cools the air to t0 = 15 ° C and W o =0.005 (steam / dry air) condition, which is the same as the environmental conditions used in the results of Table 2, and then the air is introduced into the next compressor.

[0066] In ambient air conditions of t0 = 35°C and W o =0.018 (steam / dry air), hot water inlet temperature t w =120°C, compression ratio 2.25, the following results were obtained by computer program simulation of adding a cooler to the second intercooler for cooling:

[0067] w net =263.4 kJ / kg-dry air, η th =14.11%.

[0068] However, the net power output above needs to be corrected for the power consumption of the chiller to reflect the energy consumption to achieve the cooling effect. Centrifugal chillers generally have a higher coefficient of performance (COP) than residential air conditioning systems, and COP values ​​between 8 and 9 are not uncommon (HVAC HESS: Evans 2017; and Daikin, 2020). The power consumption of the chiller can be calculated per kg of dry air using the following formula, using a chiller with a COP of 8:

[0069]

[0070] In the above formula, Δh represents the air temperature from condition t0 = 35°C, W o =0.018 to t0 = 15°C, W o = 0.005 when the enthalpy drop (unit: kJ / kg dry air). The corrected net work output and thermal efficiency are as follows:

[0071]

[0072] Compared with the environmental conditions in Table 2 o =15℃,W o= 0.005 and without centrifugal cooler cooling, the newly calculated net work output and thermal efficiency decreased by about 4.5% and 6%, respectively.

[0073] In t w =100℃ and compression ratio of 1.5, intake air condition is t0=35℃, W o = 0.018, calculated by a similar centrifugal cooler cooling procedure, and the result is consistent with t w =120°C are summarized together in Table 3.

[0074] Table 3: Environmental conditions are t0 = 35 °C and W o =0.018, the result of using a cooler to cool the compressor intermediate air, and compared with t0 = 15 ° C and W in Table 2 o =0.005.

[0075]

[0076] The results in Table 3 show that when the chiller technology is used, increasing the ambient temperature from 15°C to 35°C, the net work output is reduced by only 4.5% and the thermal efficiency is reduced by only 6% at a hot water inlet temperature of 120°C. At a hot water inlet temperature of 100°C, the reductions in net work output and thermal efficiency are 10.3% and 11.2%, respectively. Although the negative impact is greater at 100°C, its thermal efficiency is still above 10%.

[0077] The chillers used in the above disclosure are based on the type of chillers driven by mechanical energy. However, other types of chillers may also be used, including but not limited to absorption chillers, which may be driven by a heat source, which may be hot water from a hot water storage system.

[0078] According to Table 2 Figure 1 The performance results of the power plant example in the example are as follows: w At or below 100°C, power output drops dramatically, with a significant reduction in thermal efficiency. In addition, the air-steam mixture cannot be expanded through the turbine to an outlet or back pressure below ambient pressure, as is possible in most conventional steam turbine power plants.

[0079] Figure 7 Another embodiment of the air-water power plant unit of the present invention is schematically shown, which can significantly improve the performance of the power plant when the hot water inlet temperature is equal to or lower than 100°C. In this embodiment, a vacuum pump or compressor system is installed after the regenerator condenser to create a sub-ambient pressure condition at the turbine outlet or back pressure and exhaust gas and steam out of the power plant unit. Figure 7, starting from the bottom of the power plant, the ambient moist air 10 at temperature t o and humidity W o The air 10 is directed downwardly through the louvered air intake section 12 into the power unit. Sometimes a fan may be installed to assist the air intake (not shown), but this may not be necessary in some cases. The air 10 converges and flows upwardly, entering the packing 34 from the bottom to extract latent heat and sensible heat from the countercurrent hot water flow. Figure 1 The filler is similar to that in FIG. 5 , which has an associated hot water distribution system 54, a cold water collection system 58 and a peripheral water tank 60. The filler, hot water distribution system, cold water collection system and peripheral water tank are already in FIG. Figure 1 The description of the power supply fluid is described in detail and will not be repeated here. As the power supply fluid of the power device, the temperature is tw and the flow rate per unit dry air mass is r wa The hot water 52 enters the power unit through the hot water distribution system 54. After passing through the distribution system, the hot water enters the packing from the top and its temperature is t w1 , marked as 36. If the flash effect of hot water in the distribution system is ignored, then t w1 Probably close to t w In the packing, the hot water 36 conducts sufficient heat and mass transfer with the air flow 10, significantly increasing the steam content in the air flow, thereby substantially converting it into an air-steam mixture, which is marked as 38.

[0080] After energy extraction is completed in the packing 34, the air-steam mixture 38 leaves the packing with an increased humidity ratio W1 and an elevated temperature t1, but its pressure p t May be close to the ambient pressure p am , because the pressure drop across the packing is usually small, such as Figure 7 After the droplets are removed by the drift eliminator 40, the air-steam mixture 38 is directed into the turbine 42, where it is t After expansion and conversion of a portion of the heat energy into power, the air-steam mixture 48 is discharged at a reduced pressure p b , temperature t e and humidity ratio W e Leaving the turbine, where p b is the turbine back pressure, such as Figure 7 As shown. However, the air-steam mixture leaving the turbine still contains a large amount of unused heat energy, especially the steam component in the mixture. Therefore, a regenerator condenser 50 is used to recover a large amount of energy and moisture in the mixture, and the air-steam mixture 48 will continue its flow path and enter the regenerator 50.

[0081] and Figure 1 Similar to the situation in Figure 7 The regenerator 50 in the embodiment is a countercurrent direct contact condenser having a packed bed or packing structure. The cooling water flowing out of the packing 34, indicated at 56, has a temperature of t w2 , water flow rate is r wa2 The cooling water is pumped from the water tank 60 to the water distribution system 62 at the top of the regenerator and through the peripheral water tank 64. The air-steam mixture 48 is t e , W e The condition enters the regenerator 50 from the bottom of the regenerator condenser and enters the regenerator 50 at a significantly lower temperature t re and steam content W re Leaving the regenerator, referenced as 74. After the droplets are removed by the drift eliminator 72, the air-steam (or wet air) 74 exiting the regenerator 50 enters the vacuum pump or compressor system 80. The pressure in the regenerator should be close to the back pressure of the turbine, because the pressure drop across the regenerator is usually small. As previously mentioned, the back pressure p b It should be significantly lower than the ambient pressure to create a sufficient expansion ratio for the turbine operation. In this case, a vacuum pump system is required to maintain the lower pressure at the turbine outlet while increasing the pressure of the air-water mixture at the outlet of the regenerator 50 and discharging it to the environment. Figure 7 The vacuum pump system in the embodiment is an axial compressor system, but it can also be a centrifugal compressor system or other types of vacuum pump systems. In order to reduce the power consumption of the compressor system, at least one intercooler can be used.

[0082] Reference Figure 7 The compressor system 80 in the embodiment of FIG. 1 is a compressor system 80 in which the air-steam mixture 74 is heated to t re and W re The condition enters the first compressor 84 and is compressed to t c1o The air-steam mixture then enters the intercooler 86 where it is cooled to a temperature of t c2i Finally, the air-steam mixture enters the second compressor 88 and is compressed to a pressure close to the ambient pressure p am , with t ed The temperature of the air-steam mixture 74 is discharged to the surrounding environment. In order to prevent the power plant from being flooded during the rainy or snowy season, a roof structure 90 can be installed on the top of the power plant. It is well known in the art that the power consumption of the compressor system is not only sensitive to the inlet temperature of the air, but also sensitive to the humidity in the air. Taking this into account, the water flow rate of the water flow 56 flowing out of the packing outlet and pumped to the regenerator condenser may not be sufficient to significantly reduce the steam content of the air-steam mixture 74. Therefore, a cooling water flow 100 with a temperature of t c , the flow rate is r wac , where t cPreferably, it is close to ambient temperature. In addition to reducing the steam content of the air-steam mixture 74 entering the compressor system to reduce power consumption, the addition of cooling water 100 also enables the power plant to provide hot water for various users. For example, a certain amount of hot water 104 can be extracted at the bottom of the regenerator or other appropriate location for use or storage, such as Figure 7 The regenerator 50 is shown on the left side. Figure 7 The regenerator 50 shown is actually a combined structure of a regenerator and a heat or water recovery unit. Although the hot water stream 104 is shown as being extracted at the bottom of the regenerator condenser 50, the extraction point may be any suitable location of the regenerator.

[0083] To enhance Figure 7 Understanding of the system shown, Figure 8a The operating principle flow chart of the power plant is shown, where q IC represents the heat removal of the intercooler of the vacuum pump compressor system. In addition, the pressure distribution of the working fluid along the power plant height Z is Figure 8b It is also shown in the form of a schematic diagram. Figure 8b , ambient air at ambient pressure p am The air-steam mixture enters the packing layer (point 1). The air-steam mixture leaves the packing layer with a slight pressure drop (point 2) and enters the turbine to produce power (point 3). The air-steam mixture is at the turbine back pressure p b (Point 4) leaves the turbine and subsequently enters the regenerator / hot water recovery unit at Point 5. The air-steam mixture or wet air leaves the regenerator at Point 6, having significantly reduced the steam content and temperature, and enters the vacuum pump compressor system in a state at Point 7. Finally, the wet air is compressed to ambient pressure p at Point 8 am , to be discharged into the environment.

[0084] use Figure 7 The power plant with vacuum pump compressor system shown in Figure 8 has different hot water inlet temperatures t w and turbine back pressure p b The performance was evaluated under t, and some typical results are listed in Table 4 (Cao, 2022b). In all the results in the table, the ambient temperature is set to t o =15℃, the adiabatic efficiency of the compressor and turbine systems are set to 90% and 95% respectively, the diameter of the power plant is still set to D=6, and the temperature of the cooling water 100 is t c The temperature of the air-steam mixture discharged from the regenerator is 22°C, which is 2°C higher than the cooling water inlet temperature. The temperatures of the two outflow waters from the regenerator to the storage / heat source and the heat or water user are set to be 2°C lower than the air-steam mixture temperature entering the regenerator, 48°C.

[0085] For some hot water temperatures below 100°C, at low turbine back pressures, the energy consumption of the vacuum pump compressor system is too high relative to the turbine output power due to the high steam content in the air-steam mixture entering the compressor system. For this reason, similar Figure 1 The cooling method of the pre-compressor system uses a chiller to cool the air-steam mixture to 10°C below the ambient temperature before entering the compressor system, thereby significantly reducing the steam content in the mixture. Subsequently, the turbine output power and thermal efficiency are corrected to take into account the power consumption of the chiller.

[0086] Table 4: Some performance results of a power plant with a vacuum pump compressor.

[0087]

[0088] As can be seen from the results in Table 4, the performance of the air-to-water power plant using a back-vacuum pump compressor system is significantly improved when the hot water temperature is equal to or lower than 100°C. Some of the best results in the table show that the power generation capacity and secondary efficiency have reached 300MW and more than 64% respectively, which is comparable to many fossil fuel power plants even without the use of a chiller for cooling. The power generation capacity can be further increased by increasing the power plant diameter D, because the maximum pressure difference across the power plant is less than 1 bar. Although the results in the table are for a lower ambient temperature of 15°C, the power plant can also operate with limited performance loss at higher ambient temperatures. This can be achieved by using a chiller (not shown) to cool the intake ambient air and the fluid in any part of the compressor system, including the intercooler. Since the cooling effect of the chiller has been discussed in this disclosure, Figure 1 and Figure 2 The embodiments are described in connection with Figure 7 The embodiment related to FIG. 8 will not be demonstrated again.

[0089] As mentioned above, the high steam content of the gas-water mixture flowing out of the regenerator enters Figure 7 When the compressor system shown is used, the power consumption of the compressor system will be significantly increased. For this reason, a desiccant system can be deployed to reduce the vapor content of the mixture before it enters the compressor system. The desiccant assisted air conditioning system is a system that has been commercially established and applied in large-scale scenarios, which can significantly improve the efficiency of air conditioning. Figure 1 In the power system shown, whether or not the cooling system is used, the use of the desiccant system can significantly reduce the power consumption of the compressor and improve the system efficiency. In addition, if the cooling system is used, the desiccant system can also significantly reduce the load on the cooling system. In addition, when the humidity level of the ambient air is high, the desiccant system can also be used to reduce Figure 1The moisture content of the intake air is shown. Similarly, desiccant systems can also be used to remove moisture from the exhaust air, e.g. Figure 1 , Figure 4 or Figure 7 The exhaust, shown at top, significantly reduces water usage by reducing moisture losses in the exhaust gas stream before it is discharged to the environment.

[0090] The present invention Figure 1 and Figure 4 as well as Figure 7 The operating characteristics of the embodiment shown in -8 are low pressure and low temperature operation. Low pressure operation allows the power plant to be larger, thereby achieving higher power capacity. Low temperature operation allows the use of low-cost materials in the manufacture of compressors and turbines, and is suitable for the manufacture of power plant casings, which can also significantly reduce the problem of heat loss from the power plant casing to the environment.

[0091] refer to Figure 7 , for hot water inlet temperature t above 100 °C and pressure above ambient pressure w , the hot water can be flashed through the water distribution system 54 before entering the fill 34. The steam produced by the flashing will enter the turbine along with the air-steam mixture, thereby further increasing the power output of the turbine. Alternatively, a separate flash chamber can be installed, such as Fig. 9 As shown. The hot water first enters the flash chamber, where a portion of the water is flashed into steam. The flashed steam will enter the turbine for power production together with the air-steam mixture, while the remaining water in the flash chamber enters the fill to transfer mass and heat with the air entering the fill. Fig. 9 The single flash chamber shown may also be applied to other embodiments, including Figure 1 The embodiment shown. Fig. 9 As shown, the hot water from the heat source or storage system has a dimensionless flow rate r wa , due to the flash operation, its flow rate should be higher than the flow rate into the packing r wa .

[0092] So far, the air-water power device of the present invention has disclosed two main embodiments, one with a front compression system (such as Figure 1 .4), and the other is a vacuum pump compression system after the turbine (as shown in Figure 7 -8). The two methods can be combined to increase the turbine inlet pressure by the front-end compression system and reduce the turbine outlet pressure by the rear-end vacuum pump system, as shown in Fig.10 This combination can accommodate heat source temperatures significantly above 100°C, while taking advantage of the vacuum pump compression system to reduce turbine back pressure, thereby increasing the turbine expansion ratio.

[0093] In addition to the regeneration and compressor intercooling techniques, the present invention can also adopt the reheating technology used in some traditional steam power plants and gas turbine power plants, such as Fig.11 See the schematic diagram of Fig.11 , the front-end compression system raises the pressure of the working fluid to a sufficiently high level, and two turbines (or two turbine stages) are used to generate power. A reheating filler is added after the first turbine to provide energy to the working fluid before it enters the second turbine. The use of a vacuum pump compressor after the second turbine can significantly increase the expansion ratio of the second turbine. The regeneration device after the first turbine (regenerator 1) can reduce the temperature and steam content of the air-steam mixture entering the reheating filler by recovering a large amount of energy in the water flow at the outlet of the first turbine, thereby more efficiently obtaining heat energy and improving the performance of the power plant. However, in some cases, regenerator 1 can be removed. Fig.11 The system shown includes a vacuum pump compressor to reduce the back pressure of the turbine. However, the reheating mechanism can also be applied to air-water power plants without vacuum pump systems, e.g. Figure 1 An embodiment of a power plant (not shown) is shown.

[0094] Packing (direct contact heat and mass exchanger, packing), e.g. Figure 1 or Figure 7 The filler 34 shown in the figure is an important component of the air-water power device described in the present invention. However, in some cases, the filler can be removed. Fig.12 An embodiment using pressurized steam as the energy supply fluid is shown. The steam can be generated by an evaporator, a flash chamber, or a heat source (such as a solar collection system), but these devices are not shown in the figure. In this case, a mixing chamber is used to mix the steam flow with the pressurized air flow. The air-steam mixture is discharged from the mixing chamber and enters a turbine to generate power. When the steam pressure entering the mixing chamber is close to the ambient pressure, the compression system before the mixing chamber can be removed. Fig.12 The power system embodiment shown in essentially converts a conventional closed cycle steam power plant into an open cycle system.

[0095] In this disclosure, the focus is on low temperature performance. However, in principle, the air-water dynamic device can also work with high temperature heat sources, such as but not limited to concentrated solar receivers, deep geothermal wells, high temperature industrial waste heat, fossil fuel combustion or nuclear reactions.

[0096] Chiller cooling is not only useful for reducing temperature and humidity in hot summer conditions. Even at relatively low ambient temperatures, chiller cooling can still be used for performance gains. In addition, chiller cooling does not always mean reducing the fluid temperature below ambient. Any more efficient cooling methods used to reduce the temperature at these locations, either in the inlet of the compression system or in the intercooler, are possible to further improve performance.

[0097] At the inlet of a heat or water recovery unit (e.g. Figure 4 The unit shown) or a unit combined with a regenerator (e.g. Figure 7 Or the unit shown in Figure 8), the temperature of the cooling water 100 is preferably close to the ambient temperature. For this purpose, water can be drawn from water resources that can be used for water treatment facilities or other fresh water purposes. At the outlet of the recovery unit, the higher temperature water can be delivered to users related to thermal energy. If the hot water at the outlet of the unit does not need to be used, the water can be returned to the original water source or stored in a water storage facility. In the absence of thermal insulation, through a slower flow rate and a smaller pipe diameter, the water can be cooled on the way back to the original water source without involving water evaporation losses. If there is no demand for hot water use, storage capacity is not available, or a continuous water supply from a water resource to the power plant is not feasible, the water flowing out of the recovery unit can be cooled by a cooling system, whether a wet cooling system (such as a cooling tower) or a dry cooling system, to reduce the water temperature to close to the ambient temperature, and then circulate back to the recovery unit. In order to save water, it is preferred to use a dry cooling system, although this is not the subject of the present disclosure.

[0098] In the post-fossil fuel era, a large amount of heat for low-temperature needs (such as industrial applications, domestic hot water and home heating) may need to be provided by electricity. In this case, 1 kilowatt of heat can be provided by 1 kilowatt of electricity through an electric heater. However, the same amount of heat can also be provided by the lower temperature water output by the heat or water recovery unit in the air-water power plant of the present invention. In this regard, the energy carried by the hot supply hot water provided by the heat source can be almost completely utilized, either for power generation or for thermal energy needs. Therefore, the comprehensive utilization efficiency of power generation and thermal energy of the power plant can approach or even exceed 70%. In addition, after passing through the combined regenerator and heat / water recovery unit, the moisture content in the exhaust gas flow can be very low, especially when a cooler is used to further remove the steam content in the exhaust gas of the recovery unit. As a result, the net value of moisture loss discharged from the power plant to the environment can be very small.

[0099] It should be emphasized that the air-water power plant presented in this disclosure may be more inclined to large-scale power generation. However, the air-water power plant in this disclosure can also be used for small and medium-scale power generation. In addition, it should be mentioned that the term "air-steam mixture" does not exclude the possibility of liquid water in the mixture, especially at the expander outlet. In some cases, cross-flow packing or regenerators can be used, although counter-flow arrangements are more preferred. The regenerator can also be a heat exchanger in which water and the air-steam mixture are separated by a solid wall. For utility-scale power generation, turboexpanders may be the first choice; however, in certain application scenarios, including but not limited to small-scale power generation, other types of expanders, such as piston, scroll, screw, vane, Roots or rotary vane expanders, may also be considered. Similarly, for utility-scale power generation, axial compressors are the first choice; however, in certain application scenarios, including but not limited to small-scale power generation, other types of compressor systems, such as centrifugal, jet pumps, piston, scroll, screw, vane, Roots or rotary vane compressors, may also be considered.

[0100] As previously described in this disclosure, the energy supply fluid is preferably a compressed liquid to facilitate transportation and spraying in the water distribution system. However, in some cases, the energy supply fluid may also be a liquid-vapor two-phase mixture or superheated steam.

[0101] In some cases, power plant units (e.g. units involving vacuum pump compression systems, such as Figure 7 8 ) the temperature of the exhaust gas flow may be relatively high, in which case an energy recovery system may be used, although it is not shown in the figure.

[0102] In the present disclosure, the operating cycle is mainly an open cycle, and the working fluids are mainly air and water. However, the power plant disclosed in the present invention can also be operated in a closed cycle and use working fluids other than air or water, or use air in combination with other fluids (other than water), or use water in combination with other gases (other than air) as working fluids.

[0103] In this disclosure Figure 1 In the compressor system, an intercooler is used. Since the compressed air must be kept at a low temperature at the compressor outlet or before entering the packing, at least one intercooler is required, which increases the complexity of the cooling system and the effect may be limited. In order to improve the cooling of the compressor and reach a sufficiently low temperature before entering the packing, an internal cooling mechanism can be used instead of an intercooler, such as Fig.13 In this case, water is injected into the air flow in the form of droplets or mist through an injector, preferably before entering the compressor, such as Fig.13As shown on the right. The air / water mist then enters the compressor for compression. Due to the high specific heat capacity of water droplets, the heat generated during the compression process is mostly absorbed by the water droplets. Therefore, at the compressor outlet, the air flow can be kept at a sufficiently low temperature. The water droplets in the air can then be removed by a water separator, such as Fig.13 As shown, the compressed air enters the packing without being significantly affected by the water droplets. The removed water can be cooled to near ambient temperature and circulated back to the inlet of the atomizer (not shown). Although the cooling water for the compressor system can form a separate flow loop (not shown), the cold water from the packing can also be used as a coolant for the compressor, such as Fig.13 In this case, when the temperature of the removed water is low enough, water from the water separator can be directed to the top of the regeneration condenser to recover water and heat from the turbine expanded steam-air mixture.

[0104] The above internal cooling technology can also be used in the present disclosure Figure 7 and the plant configuration shown in Figure 8, where the vacuum compressor is located at the top of the plant. In this case, some temperature is t c The cooling water 100 can be used as a coolant for the compressor system and injected in the form of water mist. Then, the water removed from the compressor outlet by the water separator can be delivered to a water supply or heating user (not shown).

[0105] Now let’s move on to the issue of the adverse effects of high summer temperatures and humidity on power plants. Higher ambient temperatures can result in higher plant inlet air temperatures, higher water / heat recovery unit and regenerator cooling water temperatures, and higher compressor cooling water temperatures, all of which can reduce plant performance. Although it is possible to use Figure 6The cooling devices shown can be used to address these challenges, but may increase costs and reduce power plant efficiency. If possible, it is recommended to build air-water power plants near oceans, rivers, lakes, or wells, which can provide water with significantly lower temperatures than the ambient air in summer and can directly or indirectly alleviate the above problems. The earth is a nearly ideal heat source or heat sink due to its ability to maintain a constant temperature at a certain depth. When the above water resources are not available, groundwater can be circulated through an underground buried pipe system for cooling. When the cooling capacity of groundwater is limited, cold water at the bottom of utility-scale underground hot water storage (USUHWS) with thermal stratification conditions can be used (Cao, 2022a). In addition, utility-scale underground cold-water storage (USUCWS) can be built to store groundwater to cope with peak conditions of high temperature and high humidity in summer. Since USUCWS is only used for summer peak conditions, its storage capacity requirements will be much lower than USUHWS. Furthermore, due to its zero thermodynamic gauge pressure and low temperature, the construction cost of USUCWS is likely to be much lower than that of USUHWS.

[0106] The use of various cold water resources described above can significantly reduce the reliance on chillers. One implementation of intake air cooling is to inject cold water into the airflow and then perform a water separation process (not shown). Cold water can be used to cool Figure 4 The "cooling water from the heat source" in the heat recovery unit is cooled to a temperature lower than the ambient air temperature to more efficiently condense the steam in the water or heat recovery unit. If the heat or water output from the recovery unit is not required, the water output from the recovery unit can be cooled with cold water and returned to the recovery unit as "cooling water from the heat source". Similarly, Figure 7 In the embodiment, cold water can be used to cool cooling water 100 to reduce its temperature to below the ambient air temperature so as to more effectively condense steam in regenerator 50. If it is not necessary to use the heat or water output from regenerator 50 (see 104), the water output from the regenerator (104) can be cooled by cold water and returned to regenerator 50 as cooling water 100. In addition, cold water can also be used as Fig.13 The water source for the mistinjector shown at the bottom. Figure 4 and Figure 7In the two cases discussed in the previous section, when the cooling capacity of the chilled water is limited or the water temperature output from the recovery unit or regenerator is too high, the water temperature can be first reduced to near the ambient air temperature by an air cooling system (preferably a dry cooling system), and then further cooled to below the ambient air temperature by using chilled water from various sources. Those familiar with the art will recognize that there are many other specific implementations of using chilled water to improve the performance of air-water power plants that are not mentioned here.

[0107] The examples and embodiments described herein are for illustrative purposes only, and persons familiar with the art may propose various modifications or changes based on the content of this document, which should be included in the spirit and scope of this application. All patents and publications mentioned or cited herein are incorporated by reference in their entirety, including all diagrams and tables, provided that they are not inconsistent with the explicit explanation of this specification.

[0108] Thermal Steady State Principle of Operation:

[0109] For warm-blooded organisms, including Homo sapiens, an optimal temperature range is suggested to be inherent for the proper functioning of various activities (including but not limited to processes, functions, and equipment). This range, defined by specified upper and lower temperatures, is conceptualized as the "operational thermal steady state."

[0110] Within the framework of this balance, we identify two critical temperature thresholds, associated with activities involving either high or low temperature conditions, respectively. For high temperature activities, the critical temperature corresponds to the boiling point of water at standard atmospheric pressure. It is presumed that significant deviations beyond this limit, especially in the context of large-scale operations, would have proportionally increasing negative consequences for environmental sustainability, economic viability, and public health.

[0111] In contrast, for activities requiring low-temperature conditions, critical temperature thresholds coincide with the triple point of water. It is hypothesized that these upper and lower critical temperatures provide important guidance to humans, emphasizing the need for sustainable practices.

[0112] The core of this hypothesis emphasizes the need to operate near or within these specified temperature thresholds, thereby embodying the principle of operational thermal homeostasis and, by doing so, mitigating potential adverse consequences.

[0113] Cited References:

[0114] Cao,Yiding(2022a).“An Ultimate Solution to Phasing out Fossi1 Fuels-Part I:Utility-Scale Underground Hot Water Storage(USUHWS)for PowerProduction and Heat Supply,”Frontiers in Heat and Mass Transfer(FHMT),19-1,August 31,2022.

[0115] https: / / www.researchgate.net / publication / 363147927

[0116] Cao,Yiding(2022b).“An Ultimate Solution to Phasing out Fossil Fuels-Part II:Air-Water Thermal Power Plants,”Frontiers in Heat and Mass Transfer(FHMT),19-2,August 31,2022.

[0117] https: / / www.researchgate.net / publication / 363281042

[0118] DAIKIN(2020).Technology Development to Improve Performance with R-123ze,Retrieved 2022-1-21. https: / / www.daikinapplied.eu / news-center / the- advantages-of-r1234ze-refrigerant /

[0119] EERE-U.S.DOE Energy Efficiency and Renewable Energy,“E1ectricityGeneration,”Retrieved 2022-1-21. https: / / www.energy.gov / eere / geothermal / electricity-generation#binarycycle

[0120] Evans,P.(2017)Chiller Efficiency How to Calculate,Retrieved 2022-1-21.

[0121] https: / / theengineeringmindset.com / chiller-efficiency-calculate /

[0122] HVAC HESS.Chiller Efficiency,Retrieved 2022-1-21.

[0123] https: / / www.energy.gov.au / sites / defaul t / fi les / hvac- fa ctsheet-chiller- e ffi ciency.pd f.

[0124] Hewitt,G.F.,Shires,G.L,and Bott,T.R.(1994).Process Heat Transfer,Chapters 22 and 23,Begell House,Boca Raton.

[0125] Hill,G.B.Pring,E.J.,and Osborn,P.D.(1990).Cooling Towers-Principlesand Practices,Butterworth-Heinemann,London.

[0126] Moran,M.J.,Shapiro,HN.,Boettner,D.D.,and Bailey,M.B.(2011).Fundamentals of Engineering Thermodynamics,7th Edition,Wiley.

[0127] McQuiston,F.C.,Parker,J.D.,and Spitler,J.D.(2005).Heating,Ventilating,and Air Conditioning-Analysis and Dcsign,6th Edition,Wiley.

Claims

1. A thermal power plant comprising: at least one expander system, an energy supply fluid, an energy receiving fluid, and A direct contact heat and mass transfer exchanger facilitates heat and mass transfer from the energy supply fluid to the energy receiving fluid for expansion in the expander to produce electricity.

2. The power plant according to claim 1, wherein the energy supply fluid is water, and exists in one of the following states: liquid, liquid-vapor two-phase mixture, and superheated steam.

3. The power plant of claim 1, wherein the energy receiving fluid is one of: air, steam, an air-steam mixture, and an air-steam-liquid mixture.

4. The power plant according to claim 1, wherein the power plant further comprises at least one regenerator and recovers energy and moisture contained in the energy receiving fluid discharged from the expander.

5. The power plant according to claim 1, wherein at least one compression system is installed and the compression system is cooled by an internal cooling mechanism including the use of water.

6. The power plant according to claim 1, wherein at least one compression system is installed between the expander outlet and the exhaust port of the power plant, for maintaining the pressure at the expander outlet lower than the ambient pressure, so as to increase the expansion ratio of the expander and discharge the exhaust gas out of the power plant.

7. The power plant according to claim 1, wherein the expander system comprises at least two expanders, and a reheat heat and mass exchanger is added between the outlet of the first expander and the inlet of the second expander.

8. A power plant according to claim 1, wherein at least one cooling device is used to achieve at least one of the following: reducing the temperature of the air at the inlet of the power plant, reducing the temperature of the energy receiving fluid entering the compression system, and reducing the temperature of the energy receiving fluid at a certain position between the inlet and outlet of the installed compression system.

9. The power plant according to claim 1, wherein the energy supply fluid is liquid, and part of the liquid is flashed into steam before entering the direct contact heat and mass transfer exchanger, and the flashed steam bypasses the exchanger and enters the expander.

10. The power plant of claim 2, wherein the water is delivered to the user via one of the following systems: a regenerator and a heat or water recovery unit.

11. The power plant according to claim 1, wherein the energy supply fluid is steam, and the steam enters the expander together with the air without involving a heat and mass exchanger.

12. The power plant of claim 1, wherein a desiccant system is employed to at least one of: reduce the humidity of the power plant inlet air, reduce the humidity of the air-steam mixture entering the compression system, and recover moisture from the exhaust stream before it enters the environment.

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