CN115822743B - An absorption cogeneration system based on large temperature difference heat exchange - Google Patents
An absorption cogeneration system based on large temperature difference heat exchange Download PDFInfo
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Abstract
本发明公开了一种基于大温差换热的吸收式热电联产系统，包括两个部分：动力循环系统和两级式吸收式换热器系统。动力循环系统用于发电，两级式吸收式换热器系统用于供热。循环工质在动力循环系统中加热后膨胀做功，输出电能。区域供热网络连接两级式吸收式换热器中的吸收器和冷凝器，并吸收所释放的吸收热和冷凝热，向热用户提供热水。本发明利用吸收式换热器的大温差换热特性和动力循环的高效发电能力，对低温热源进行梯级利用，可以实现热源的出口温度低于冷源的入口温度，使得热源出口温度大幅下降，由此显著提高了热源能量的利用率并用于供电和供热，从而减少发电和供暖能耗以及碳排放。
The present invention discloses an absorption cogeneration system based on large temperature difference heat exchange, which includes two parts: a power cycle system and a two-stage absorption heat exchanger system. The power cycle system is used for power generation, and the two-stage absorption heat exchanger system is used for heat supply. After the circulating working fluid is heated in the power cycle system, it expands and performs work, and outputs electrical energy. The regional heating network connects the absorber and the condenser in the two-stage absorption heat exchanger, absorbs the released absorption heat and condensation heat, and provides hot water to heat users. The present invention utilizes the large temperature difference heat exchange characteristics of the absorption heat exchanger and the efficient power generation capacity of the power cycle to perform cascade utilization of low-temperature heat sources, which can achieve that the outlet temperature of the heat source is lower than the inlet temperature of the cold source, so that the outlet temperature of the heat source is greatly reduced, thereby significantly improving the utilization rate of the heat source energy and using it for power supply and heat supply, thereby reducing power generation and heating energy consumption and carbon emissions.
Description
Technical Field
The invention belongs to the technical field of energy, relates to the fields of absorption heat exchangers, power circulation and cogeneration, and particularly relates to an absorption cogeneration system based on large-temperature-difference heat exchange.
Background
Because of the advantages of simple structure, high reliability, convenience in installation and maintenance, strong adaptability to the temperature and type of heat source, and the like, power cycles represented by organic rankine cycles, organic flash cycles, brayton cycles, kalina cycles, and the like are widely studied in the fields of waste heat recovery and cogeneration. In a power cycle evaporator, the existence of the pinch temperature difference makes the matching problem of the heat source temperature difference difficult to be improved remarkably, and further makes the outlet temperature of the hot side fluid be far higher than the inlet temperature of the cold side fluid. The small temperature drop of the heat source results in a large part of heat energy being wasted, and how to further utilize the part of heat energy is an urgent problem.
Disclosure of Invention
In order to solve the problem of low heat source utilization rate, the invention aims to provide an absorption type cogeneration system based on large-temperature-difference heat exchange, so as to reduce the temperature at the outlet of a heat source to the maximum extent and realize the maximum utilization of heat energy.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
The absorption type cogeneration system based on large-temperature-difference heat exchange comprises a power circulation system and a two-stage absorption type heat exchanger system, wherein the two-stage absorption type heat exchanger system comprises a first-stage absorption type heat pump, a second-stage absorption type heat pump and a plate type heat exchanger, the first-stage absorption type heat pump comprises a first generator, a first condenser, a first evaporator, a first absorber and a first solution heat exchanger, and the second-stage absorption type heat pump comprises a second generator, a second condenser, a second evaporator, a second absorber and a second solution heat exchanger;
the heat source releases heat in the power circulation system to generate electricity;
The heat source after releasing heat flows through the first generator, the second generator, the plate heat exchanger, the second evaporator and the first evaporator in sequence, and further releases heat;
The regional heating network is divided into three branches, the first branch sequentially passes through the first absorber and the first condenser, the tail end of the first branch is connected with a third mixer, the second branch sequentially passes through the second absorber and the second condenser, the tail end of the second branch is connected with the third mixer, the cold side inlet of the plate-type heat exchanger of the third branch is connected with the third mixer, the cold side outlet of the plate-type heat exchanger is connected with the third mixer, and the third mixer supplies heat to a hot user.
In one embodiment, the power circulation system is an organic Rankine circulation system, an organic flash evaporation circulation system, a Brayton circulation system or a Kalina circulation system, and the heat source is waste water, flue gas or hot oil to heat working media of the power circulation system.
In one embodiment, the first-stage absorption heat pump and the second-stage absorption heat pump both use lithium bromide solution as working media, wherein a liquid-phase outlet of the first generator is lithium bromide concentrated solution, the liquid-phase outlet is connected with a hot-side inlet of the first solution heat exchanger, a hot-side outlet of the first solution heat exchanger is connected with a hot-side inlet of the first absorber through a second throttle valve, a gas-phase outlet of the first generator is water vapor, the gas-phase outlet is connected with a hot-side inlet of the first condenser, the hot-side outlet of the first condenser is connected with a cold-side inlet of the first evaporator through a first throttle valve, the cold-side outlet of the first evaporator is connected with the hot-side inlet of the first absorber, the hot-side outlet of the first absorber is lithium bromide diluted solution, the gas-phase outlet of the first solution heat exchanger is connected with the cold-side inlet of the first generator through a first booster pump, and absorption heat pump circulation is completed;
the liquid phase outlet of the second generator is a lithium bromide concentrated solution, the liquid phase outlet of the second generator is connected with the hot side inlet of the second solution heat exchanger, the hot side outlet of the second solution heat exchanger is connected with the hot side inlet of the second absorber through a fourth throttle valve, the gas phase outlet of the second generator is water vapor, the gas phase outlet of the second generator is connected with the hot side inlet of the second condenser, the hot side outlet of the second condenser is connected with the cold side inlet of the second evaporator through a third throttle valve, the cold side outlet of the second evaporator is connected with the hot side inlet of the second absorber, the hot side outlet of the second absorber is a lithium bromide diluted solution, the gas phase outlet of the second solution heat exchanger is connected with the cold side inlet of the second generator through a second booster pump, and absorption heat pump circulation is completed.
In one embodiment, the first generator is composed of a first heat exchanger and a first two-phase separator, wherein the cold side outlet of the first heat exchanger is connected with the inlet of the first two-phase separator, the cold side inlet of the first heat exchanger is the cold side inlet of the first generator, the hot side inlet is the hot side inlet of the first generator, the liquid phase outlet of the first two-phase separator is the liquid phase outlet of the first generator, and the gas phase outlet of the first two-phase separator is the gas phase outlet of the first generator;
the first absorber consists of a third heat exchanger and a first mixer, wherein two inlets of the first mixer are hot side inlets of the first absorber, an outlet of the first mixer is connected with the hot side inlet of the third heat exchanger, and a hot side outlet of the third heat exchanger is a hot side outlet of the first absorber;
The second generator consists of a second heat exchanger and a second two-phase separator, wherein the cold side outlet of the second heat exchanger is connected with the inlet of the second two-phase separator, the cold side inlet of the second heat exchanger is the cold side inlet of the second generator, the hot side inlet and outlet are the hot side inlet and outlet of the second generator, the liquid phase outlet of the second two-phase separator is the liquid phase outlet of the second generator, and the gas phase outlet of the second two-phase separator is the gas phase outlet of the second generator;
The second absorber consists of a fourth heat exchanger and a second mixer, two inlets of the second mixer are hot side inlets of the second absorber, an outlet of the second mixer is connected with the hot side inlet of the fourth heat exchanger, and a hot side outlet of the fourth heat exchanger is a hot side outlet of the second absorber.
In one embodiment, the heat source after releasing heat is connected to a hot side inlet of the first heat exchanger, a hot side outlet of the first heat exchanger is connected to a hot side inlet of the second heat exchanger, a hot side outlet of the second heat exchanger is connected to a hot side inlet of the plate heat exchanger, a hot side outlet of the plate heat exchanger is connected to a hot side inlet of the second evaporator, a hot side outlet of the second evaporator is connected to a hot side inlet of the first evaporator, and a hot side outlet of the first evaporator is a heat source outlet.
In one embodiment, the hot side outlets of the first and second condensers are in a saturated liquid state and the cold side outlets of the first and second evaporators are in a saturated gaseous state.
In one embodiment, the first-stage absorption heat pump and the second-stage absorption heat pump are different in parameters, wherein the parameters comprise the concentration of lithium bromide solution and high-side and low-side pressures in an absorption heat pump cycle, the concentration of lithium bromide solution in the second-stage absorption heat pump is lower than that in the first-stage absorption heat pump, the pressure after throttling by the first throttling valve is smaller than that after throttling by the third throttling valve, and the pressure after throttling by the second throttling valve is smaller than that after throttling by the fourth throttling valve.
In one embodiment, each booster pump uses electric energy generated by the power circulation system as an energy source.
In one embodiment, after further heat release via the first evaporator, the heat source outlet temperature drops below the heat sink inlet temperature.
In one embodiment, the final outlet temperature of the heat source fluid is lower than the return water temperature of the heat user.
Compared with the prior art, the invention has the beneficial effects that:
1. by using the absorption heat exchanger technology, the outlet temperature of the heat source is greatly reduced on the premise of not wasting the heat energy of the heat source, and large-temperature-difference heat exchange is performed, so that the heat energy of the heat source is efficiently converted into electric energy and heat energy required by heat users, and the heat source utilization rate is remarkably improved.
2. Compared with the traditional single-stage absorption heat exchanger, the two-stage absorption heat exchanger has greatly reduced heat exchange loss in the heat exchange process. Compared with the multistage absorption heat exchanger, the multistage absorption heat exchanger has better circulation regulation and control capability.
3. The power consumption of the booster pump in the absorption heat pump cycle is negligibly small, the booster pump can be driven by the electric energy output by the turbine in the organic Rankine cycle, the heat source energy can be converted in a high proportion under the condition that no additional electric power or heat is needed, and meanwhile, considerable benefits can be brought to power supply and heating.
4. The absorption heat pump is in closed circulation, is environment-friendly and has high reliability. The whole cogeneration system can flexibly match heat sources with different types, flow rates and temperatures.
5. According to engineering practice, different types of power cycles such as organic Rankine cycle, organic flash cycle, brayton cycle or kalina cycle can be adopted, so that the final outlet temperature of a heat source can be greatly reduced, and the heat source utilization rate is improved.
Drawings
FIG. 1 is a schematic diagram of the structure of the present invention.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples.
As shown in figure 1, the invention relates to an absorption type cogeneration system based on large-temperature-difference heat exchange, which mainly comprises a power circulation system and a two-stage absorption type heat exchanger system. The heat source releases heat in the power circulation system to heat working medium of the power circulation system, and the heated working medium is used for doing work and generating electricity. The two-stage absorption heat exchanger system comprises a first stage absorption heat pump, a second stage absorption heat pump and a plate heat exchanger 21. The first stage absorption heat pump comprises a first generator, a first condenser 3, a first evaporator 5, a first absorber and a first solution heat exchanger 6, and the second stage absorption heat pump comprises a second generator, a second condenser 13, a second evaporator 15, a second absorber and a second solution heat exchanger 16.
The heat source after the heat release of the power circulation system flows through the first generator, the second generator, the plate heat exchanger 21, the second evaporator 15 and the first evaporator 5 in sequence, and further releases the heat.
The regional heating network is divided into three branches, the first branch sequentially passes through the first absorber and the first condenser 3, the tail end of the first branch is connected with the third mixer 22, the second branch sequentially passes through the second absorber and the second condenser 13, the tail end of the second branch is connected with the third mixer 22, the cold side inlet of the plate-type heat exchanger 21 of the third branch exchanges heat with a heat source flowing out of the second generator, the cold side outlet of the plate-type heat exchanger 21 is connected with the third mixer 22, and heat can be supplied to a heat user by utilizing the third mixer 22. The three branches exchange heat with the heat source indirectly or directly through the two-stage absorption heat exchanger, and heat released by the heat source is fully acquired and then supplied to a heat user.
In the invention, the power circulation system can be different heat engines such as an organic Rankine circulation system, an organic flash evaporation circulation system, a Brayton circulation system or a kalina circulation system, and the heat source can be other common waste heat carriers such as waste water, smoke or hot oil.
In the embodiment of the invention, the power circulation system takes an organic rankine cycle heat engine as an example, and comprises a third evaporator 23, a turbine 24, a third condenser 25 and a circulation pump 26, wherein the heat source firstly releases heat to heat working medium in the organic rankine cycle system, and the organic rankine cycle system utilizes the heated working medium to generate electricity. For example, the organic rankine cycle uses R245fa, R134a or other environmental organics as the working fluid. The heat source is firstly connected with the hot side inlet of the third evaporator 23, the heat source coming out of the third evaporator 23 flows through the first generator, the second generator, the plate heat exchanger 21, the second evaporator 15 and the first evaporator 5 in sequence, the heat source releases heat, and the temperature is gradually reduced. The cold side outlet of the third evaporator 23 is connected with the inlet of the turbine 24, the organic working medium at the inlet of the turbine 24 is in a saturated gaseous state or a superheated state, and the organic working medium expands in the turbine 24 to do work and outputs electric energy. The exhaust gas at the outlet of the turbine 24 is connected with the hot side inlet of the third condenser 25, the cooling water inlet is connected with the cold side inlet of the third condenser 25, the hot side outlet of the third condenser 25 is in a saturated liquid state, and the condensation heat is taken away by the cooling water. The hot side outlet of the third condenser 25 is connected with the cold side inlet of the third evaporator 23 through a circulating pump 26, and the organic working medium returns to the initial point and starts the next circulation, namely the circulating working medium.
In the embodiment of the invention, the first-stage absorption heat pump and the second-stage absorption heat pump both use lithium bromide solution as working media. Lithium bromide solution is suitable for use in heating systems, while refrigeration systems typically use aqueous ammonia solutions. Compared with the ammonia water solution, the thermodynamic performance of the absorption heat pump cycle adopting the lithium bromide solution is better.
For the first-stage absorption heat pump, the liquid phase outlet of the first generator is lithium bromide concentrated solution, the liquid phase outlet is connected with the hot side inlet of the first solution heat exchanger 6, the hot side outlet of the first solution heat exchanger 6 is connected with the hot side inlet of the first absorber through the second throttle valve 7, the gas phase outlet of the first generator is water vapor, the gas phase outlet of the first generator is connected with the hot side inlet of the first condenser 3, the hot side outlet of the first condenser 3 is in saturated liquid state, the gas phase outlet is connected with the cold side inlet of the first evaporator 5 through the first throttle valve 4, the cold side outlet of the first evaporator 5 is in saturated gas state, the gas phase outlet is connected with the hot side inlet of the first absorber, the hot side outlet of the first absorber is lithium bromide diluted solution, the gas phase outlet of the first solution heat exchanger 6 is connected with the cold side inlet of the first generator through the first booster pump 10, and the cold side outlet of the first solution heat exchanger 6 is connected with the cold side inlet of the first generator, so that the absorption heat pump cycle is completed.
For the second-stage absorption heat pump, the liquid phase outlet of the second generator is a lithium bromide concentrated solution, is connected with the hot side inlet of the second solution heat exchanger 16, the hot side outlet of the second solution heat exchanger 16 is connected with the hot side inlet of the second absorber through the fourth throttle valve 17, the gas phase outlet of the second generator is water vapor, is connected with the hot side inlet of the second condenser 13, the hot side outlet of the second condenser 13 is in a saturated liquid state, is connected with the cold side inlet of the second evaporator 15 through the third throttle valve 14, the cold side outlet of the second evaporator 15 is in a saturated gaseous state, is connected with the hot side inlet of the second absorber, the hot side outlet of the second absorber is lithium bromide diluted solution, is connected with the cold side inlet of the second solution heat exchanger 16 through the second booster pump 20, and the cold side outlet of the second solution heat exchanger 16 is connected with the cold side inlet of the second generator, so that the absorption heat pump cycle is completed. Namely, the heat source which releases part of the heat in the first-stage absorption heat pump enters the second generator, the water vapor generated in the second generator sequentially flows through the second condenser 13, the third throttle valve 14 and the second evaporator 15 and finally flows into the second absorber, the lithium bromide concentrated solution generated in the second generator enters the second absorber through the second solution heat exchanger 16 and the fourth throttle valve 17 and absorbs the saturated water vapor from the second evaporator 15, and the formed lithium bromide dilute solution is preheated in the second solution heat exchanger 16 and finally returns to the second generator.
Further, in the embodiment of the present invention, the first heat exchanger 1 and the first two-phase separator 2 form a first generator of the first stage absorption heat pump, the cold side outlet of the first heat exchanger 1 is connected to the inlet of the first two-phase separator 2, the cold side inlet of the first heat exchanger 1 is the cold side inlet of the first generator, the hot side inlet is the hot side inlet of the first generator, the liquid phase outlet of the first two-phase separator 2 is the liquid phase outlet of the first generator, and the gas phase outlet of the first two-phase separator 2 is the gas phase outlet of the first generator.
Further, in the embodiment of the present invention, the third heat exchanger 9 and the first mixer 8 form a first absorber of the first stage absorption heat pump, two inlets of the first mixer 8 are hot side inlets of the first absorber, an outlet of the first mixer 8 is connected with the hot side inlet of the third heat exchanger 9, and a hot side outlet of the third heat exchanger 9 is a hot side outlet of the first absorber.
Further, in the embodiment of the present invention, the second heat exchanger 11 and the second two-phase separator 12 form a second generator of the second-stage absorption heat pump, the cold side outlet of the second heat exchanger 11 is connected to the inlet of the second two-phase separator 12, the cold side inlet of the second heat exchanger 11 is the cold side inlet of the second generator, the hot side inlet is the hot side inlet of the second generator, the liquid phase outlet of the second two-phase separator 12 is the liquid phase outlet of the second generator, and the gas phase outlet of the second two-phase separator 12 is the gas phase outlet of the second generator.
Further, in the embodiment of the present invention, the fourth heat exchanger 19 and the second mixer 18 form a second absorber of the second-stage absorption heat pump, two inlets of the second mixer 18 are hot side inlets of the second absorber, an outlet of the second mixer 18 is connected to the hot side inlet of the fourth heat exchanger 19, and a hot side outlet of the fourth heat exchanger 19 is a hot side outlet of the second absorber.
At this time, the heat source after releasing the heat is connected with the hot side inlet of the first heat exchanger 1, the hot side outlet of the first heat exchanger 1 is connected with the hot side inlet of the second heat exchanger 11, the hot side outlet of the second heat exchanger 11 is connected with the hot side inlet of the plate heat exchanger 21, the hot side outlet of the plate heat exchanger 21 is connected with the hot side inlet of the second evaporator 15, the hot side outlet of the second evaporator 15 is connected with the hot side inlet of the first evaporator 5, and the hot side outlet of the first evaporator 5 is the final outlet of the heat source.
Further, in an embodiment of the present invention, the parameters of the first stage absorption heat pump and the second stage absorption heat pump are different, where the parameters mainly refer to the concentration of the lithium bromide solution and the high side and low side pressures in the absorption heat pump cycle. Compared with the first-stage absorption heat pump, the concentration of the lithium bromide solution in the second-stage absorption heat pump cycle is lower, the pressure after throttling of the throttle valve is higher, namely the pressure after throttling of the first throttle valve 4 is smaller than the pressure after throttling of the third throttle valve 14, and the pressure after throttling of the second throttle valve 7 is smaller than the pressure after throttling of the fourth throttle valve 17, so that the evaporation temperature is higher, and the occurrence temperature is lower. The heat source passes through the first generator, the second generator and the plate heat exchanger 21, then enters the second evaporator 15 of the second-stage absorption heat pump, then enters the first evaporator 5 of the first-stage absorption heat pump, the temperature is gradually reduced, and the final outlet temperature of the heat source can be reduced below the inlet temperature of the cold source. Therefore, by setting the related parameters of the two absorption heat pump cycles to different values, the heat energy of the heat source can be utilized in a cascade manner, the heat exchange loss in the heat exchange process is reduced, and the outlet temperature is reduced to the minimum level.
In an embodiment of the invention, the cold source comprises an organic working medium on the cold side of a power cycle (for example an organic rankine cycle) evaporator and hot water for the hot user. Therefore, the cold source inlet is the cold side inlet of the evaporator 23 (temperature around 35 ℃) and the cold side inlets of the heat exchanger 9, the heat exchanger 19 and the plate heat exchanger 21 (temperature 40 ℃).
Based on the system, the specific implementation flow of the invention is as follows:
The invention adopts different types of power circulation systems, taking an organic Rankine cycle heat engine as an example, taking hot water or flue gas at 130 ℃ as a waste heat source, and sequentially heating organic working media in the organic Rankine cycle third evaporator 23, lithium bromide dilute solution in the first generator and the second generator, hot water in the plate heat exchanger 21, liquid and gaseous water in the second evaporator 15 and the first evaporator 5. In the organic Rankine cycle system, R245fa is used as a working medium. The working medium is evaporated by a heat source in the third evaporator 23, flows into the turbine 24 in a saturated gas state or a superheated state to do expansion work, and outputs electric energy. The working medium after expansion work is condensed by cooling water in the third condenser 25, the condensed organic working medium is in a saturated liquid state, and then the working medium is pressurized by the third booster pump 26 and flows back to the third evaporator 23, and the organic Rankine cycle is completed. The heat source after releasing part of the heat in the organic Rankine cycle system enters the two-stage absorption heat exchanger, and releases the heat with different temperature levels to the first-stage and second-stage absorption heat pumps and the plate heat exchanger 21. The component parts and the working flow of the second-stage absorption heat pump are the same as those of the first-stage absorption heat pump. Taking the first stage absorption heat pump as an example, a heat source first enters a first generator and releases heat, where a dilute lithium bromide solution is heated to form a two-phase mixture of concentrated lithium bromide solution and water vapor. The lithium bromide concentrated solution enters a first solution heat exchanger 6 to preheat the lithium bromide dilute solution from the first absorber, the pressure of the lithium bromide concentrated solution after heat exchange is reduced from 14.77kPa to 2.16kPa through the throttling action of a second throttle valve 7 and flows into the first absorber, the superheated steam generated in the first generator enters a first condenser 3 to transfer heat to hot water in a district heating network, the steam is condensed into saturated liquid state and then passes through a first throttle valve 4, the pressure is reduced to 2.16kPa, the solution is in a two-phase region, then enters a first evaporator 5 and is evaporated into saturated gas state by heat source fluid from a second evaporator 15, and finally flows into the first absorber. In the first absorber, the concentrated lithium bromide solution absorbs water vapor to become a dilute lithium bromide solution and releases a large amount of heat, which is also used for district heating. The lithium bromide dilute solution at the outlet of the first absorber passes through the first booster pump 10, the pressure is increased to 14.77kPa, then enters the first solution heat exchanger 6 to be preheated by the lithium bromide concentrated solution, and then returns to the first generator, thus completing the whole absorption heat pump cycle. In the second-stage absorption heat pump, the pressure before throttling of the third throttle valve 14 and the fourth throttle valve 17 is 14.75kPa, and the pressure after throttling is 3.57kPa. Compared with the first-stage absorption heat pump, the pressure of the second-stage absorption heat pump after throttling by the throttle valve is larger, so that the evaporation temperature is higher, the occurrence temperature is lower, and the heat source energy is utilized in a cascade mode. After releasing heat in the second generator, the heat source fluid from the first generator enters the plate heat exchanger 21 to heat water in the district heating network, the heat source temperature is greatly reduced and flows into the second evaporator 15 and the first evaporator 5 to further release heat.
The regional heating network is divided into three branches, the first branch sequentially passes through a first absorber and a first condenser 3 in the first-stage absorption heat pump, the second branch sequentially passes through a second absorber and a second condenser 13 in the second-stage absorption heat pump, the third branch exchanges heat with a heat source flowing out of the second generator through a cold side inlet of a plate-type heat exchanger 21, and the three branches indirectly or directly exchange heat with the heat source through the two-stage absorption heat exchanger, so that heat released by the heat source is fully acquired and then is supplied to a heat user. While the electrical energy generated in the orc cycle can be used to drive the booster pump and power. Therefore, the two-stage absorption heat exchange system is suitable for heat source scenes with different types, flow rates and temperatures, and has the characteristic of large temperature difference heat exchange due to the two-stage absorption heat exchange system. For example, in this embodiment, the final outlet temperature of the heat source fluid may be reduced to 24 ℃ below the return water temperature (40 ℃) of the heat user, and the water supply temperature of the heat user is 50 ℃, so as to realize large-temperature-difference heat exchange of the heat source.
In more embodiments of the present invention, the heat source type includes hot water, flue gas, steam, heat conducting oil, etc., the flow rate of the heat source varies within the range of 10kg/s-60kg/s, the temperature range of the heat source ranges from 100 ℃ to 150 ℃, and the heat source scenario refers to that in different systems of waste heat recovery, cogeneration, renewable energy power generation, energy storage, etc., only the heat related to the absorption of the hot fluid by the evaporator can be applied to the system.
In summary, the invention combines different types of power circulation systems with the two-stage absorption heat exchanger system by utilizing the large-temperature-difference heat exchange characteristic of the absorption heat exchanger, and performs cascade utilization on the heat energy of the low-temperature heat source, so that the outlet temperature of the heat source can be reduced below the inlet temperature of the cold source, the heat source utilization rate is obviously improved, and the heat source energy is efficiently converted into electric energy and heat energy required by a heat user on the premise of not wasting the heat energy. Compared with the traditional single-stage absorption heat exchanger, the two-stage absorption heat exchanger has greatly reduced heat exchange loss in the heat exchange process. Compared with the multistage absorption heat exchanger, the multistage absorption heat exchanger has better circulation regulation and control capability. The absorption heat pump cycle is closed circulation, is environment-friendly and has high reliability. The whole cogeneration system can flexibly match heat sources with different types, flow rates and temperatures, is simultaneously suitable for different heat engines such as organic Rankine cycle, organic flash evaporation cycle, brayton cycle or kalina cycle, and the like, greatly improves the heat source utilization rate, and can bring considerable benefits in addition to power supply and heating.
Claims (10)
1. The absorption type cogeneration system based on large-temperature-difference heat exchange is characterized by comprising a power circulation system and a two-stage absorption type heat exchanger system, wherein the two-stage absorption type heat exchanger system comprises a first-stage absorption type heat pump, a second-stage absorption type heat pump and a plate type heat exchanger (21), the first-stage absorption type heat pump comprises a first generator, a first condenser (3), a first evaporator (5), a first absorber and a first solution heat exchanger (6), and the second-stage absorption type heat pump comprises a second generator, a second condenser (13), a second evaporator (15), a second absorber and a second solution heat exchanger (16);
the heat source releases heat in the power circulation system to generate electricity;
The heat source after releasing heat flows through the first generator, the second generator, the plate heat exchanger (21), the second evaporator (15) and the first evaporator (5) in sequence, and further releases heat;
The regional heating network is divided into three branches, wherein the first branch sequentially passes through the first absorber and the first condenser (3), the tail end of the first branch is connected with a third mixer (22), the second branch sequentially passes through the second absorber and the second condenser (13), the tail end of the second branch is connected with the third mixer (22), the third branch is connected with a cold side inlet of a plate heat exchanger (21), a cold side outlet of the plate heat exchanger (21) is connected with the third mixer (22), and the third mixer (22) supplies heat to a hot user.
2. The absorption heat and power cogeneration system based on large-temperature-difference heat exchange according to claim 1, wherein the power circulation system is an organic Rankine circulation system, an organic flash evaporation circulation system, a Brayton circulation system or a Kalina circulation system, and the heat source is waste water, flue gas or hot oil for heating working media of the power circulation system.
3. The absorption cogeneration system based on large temperature difference heat exchange according to claim 1, wherein the first-stage absorption heat pump and the second-stage absorption heat pump both use lithium bromide solution as working medium, wherein the liquid-phase outlet of the first generator is lithium bromide concentrated solution, the liquid-phase outlet of the first generator is connected with the hot-side inlet of the first solution heat exchanger (6), the hot-side outlet of the first solution heat exchanger (6) is connected with the hot-side inlet of the first absorber through a second throttle valve (7), the gas-phase outlet of the first generator is water vapor, the liquid-phase outlet of the first generator is connected with the hot-side inlet of the first condenser (3), the hot-side outlet of the first condenser (3) is connected with the cold-side inlet of the first evaporator (5) through a first throttle valve (4), the cold-side outlet of the first evaporator (5) is connected with the hot-side inlet of the first absorber, the hot-side outlet of the first absorber is lithium bromide diluted solution, the gas-phase outlet of the first solution heat exchanger (6) is connected with the cold-side inlet of the first absorber through a first booster pump (10), and the first-side outlet of the first solution heat exchanger (6) is connected with the cold-side inlet of the first generator;
The liquid phase outlet of the second generator is a lithium bromide concentrated solution, the liquid phase outlet of the second generator is connected with the hot side inlet of the second solution heat exchanger (16), the hot side outlet of the second solution heat exchanger (16) is connected with the hot side inlet of the second absorber through a fourth throttle valve (17), the gas phase outlet of the second generator is water vapor, the gas phase outlet of the second generator is connected with the hot side inlet of the second condenser (13), the hot side outlet of the second condenser (13) is connected with the cold side inlet of the second evaporator (15) through a third throttle valve (14), the cold side outlet of the second evaporator (15) is connected with the hot side inlet of the second absorber, the hot side outlet of the second absorber is lithium bromide diluted solution, the gas phase outlet of the second solution heat exchanger (16) is connected with the cold side inlet of the second generator through a second booster pump (20), and absorption heat pump circulation is completed.
4. The absorption co-generation system based on large temperature difference heat exchange according to claim 3, wherein the first generator consists of a first heat exchanger (1) and a first two-phase separator (2), a cold side outlet of the first heat exchanger (1) is connected with an inlet of the first two-phase separator (2), the cold side inlet of the first heat exchanger (1) is a cold side inlet of the first generator, a hot side inlet is a hot side inlet of the first generator, a liquid phase outlet of the first two-phase separator (2) is a liquid phase outlet of the first generator, and a gas phase outlet of the first two-phase separator (2) is a gas phase outlet of the first generator;
The first absorber consists of a third heat exchanger (9) and a first mixer (8), wherein two inlets of the first mixer (8) are hot side inlets of the first absorber, an outlet of the first mixer (8) is connected with the hot side inlet of the third heat exchanger (9), and a hot side outlet of the third heat exchanger (9) is a hot side outlet of the first absorber;
the second generator consists of a second heat exchanger (11) and a second two-phase separator (12), wherein the cold side outlet of the second heat exchanger (11) is connected with the inlet of the second two-phase separator (12), the cold side inlet of the second heat exchanger (11) is the cold side inlet of the second generator, the hot side inlet and outlet are the hot side inlet and outlet of the second generator, the liquid phase outlet of the second two-phase separator (12) is the liquid phase outlet of the second generator, and the gas phase outlet of the second two-phase separator (12) is the gas phase outlet of the second generator;
The second absorber consists of a fourth heat exchanger (19) and a second mixer (18), two inlets of the second mixer (18) are hot side inlets of the second absorber, an outlet of the second mixer (18) is connected with the hot side inlet of the fourth heat exchanger (19), and a hot side outlet of the fourth heat exchanger (19) is a hot side outlet of the second absorber.
5. The absorption cogeneration system based on large-temperature-difference heat exchange according to claim 4, wherein the heat source after releasing heat is connected with the hot side inlet of the first heat exchanger (1), the hot side outlet of the first heat exchanger (1) is connected with the hot side inlet of the second heat exchanger (11), the hot side outlet of the second heat exchanger (11) is connected with the hot side inlet of the second evaporator (15), the hot side outlet of the plate heat exchanger (21) is connected with the hot side inlet of the first evaporator (5), and the hot side outlet of the first evaporator (5) is a heat source outlet.
6. The absorption co-generation system based on large temperature difference heat exchange according to claim 3 or 4 or 5, characterized in that the hot side outlets of the first condenser (3) and the second condenser (13) are in saturated liquid state and the cold side outlets of the first evaporator (5) and the second evaporator (15) are in saturated gaseous state.
7. The absorption heat and power cogeneration system based on large temperature difference heat exchange according to claim 3, 4 or 5, wherein the parameters of the first stage absorption heat pump and the second stage absorption heat pump are different, the parameters include the concentration of lithium bromide solution and the high side and low side pressure in the absorption heat pump cycle, wherein the concentration of lithium bromide solution of the second stage absorption heat pump is lower than that of the first stage absorption heat pump, the pressure after throttling by the first throttling valve (4) is lower than that after throttling by the third throttling valve (14), and the pressure after throttling by the second throttling valve (7) is lower than that after throttling by the fourth throttling valve (17).
8. The absorption co-generation system based on large temperature difference heat exchange according to claim 3, 4 or 5, wherein each booster pump uses electric energy generated by the power circulation system as an energy source.
9. The absorption cogeneration system based on large temperature differential heat exchange according to claim 1, wherein the heat source outlet temperature drops below the cold source inlet temperature after further heat release via said first evaporator (5).
10. The large temperature differential heat exchange based absorption cogeneration system of claim 1 wherein the final outlet temperature of the heat source fluid is lower than the return water temperature of the heat consumer.
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| CN105650938A (en) * | 2016-01-08 | 2016-06-08 | 上海缔森能源技术有限公司 | Absorption refrigeration method and device for all-electric reuse of discharged heat |
| CN111550947A (en) * | 2020-06-22 | 2020-08-18 | 广东电网有限责任公司广州供电局 | A novel lithium bromide absorption heat pump and its heating method |
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| CN102797522B (en) * | 2012-08-28 | 2015-10-28 | 西安交通大学 | A kind of Low and mid temperature heat recovery system realizing cold electricity/cogeneration of heat and power |
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| CN111550947A (en) * | 2020-06-22 | 2020-08-18 | 广东电网有限责任公司广州供电局 | A novel lithium bromide absorption heat pump and its heating method |
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