阅读说明：本技术 一种优先供热的两级有机朗肯循环热电联供系统及调控方法 (Two-stage organic Rankine cycle combined heat and power system with preferential heat supply function and regulation and control method ) 是由 徐东海 梁钰 白玉 郭树炜 魏宁 王瀚 于 2020-06-24 设计创作，主要内容包括：本发明公开了一种优先供热的两级有机朗肯循环热电联供系统及调控方法,属于能源技术领域。包括余热换热单元、导热油分配及控制单元、供热单元、第一有机朗肯循环发电单元和第二有机朗肯循环发电单元,余热换热单元将中温的烟气余热能量进行一级换热至导热油,导热油由导热油分配及控制单元分配至供热单元和第一有机朗肯循环发电单元,供热单元和第一有机朗肯循环发电单元并联工作,与导热油换热后的烟气余热进入第二有机朗肯循环发电单元进行二级发电。通过一级换热得到高温热量,通过导热油分配及控制系统优先满足供热系统的电负荷,达到优先稳定供热的目的,剩余热量再通过两个有机朗肯循环发电系统进行两级发电,实现更优热电联供比例。(The invention discloses a two-stage organic Rankine cycle combined heat and power system with preferential heat supply and a regulation and control method, and belongs to the technical field of energy. The system comprises a waste heat exchange unit, a heat conduction oil distribution and control unit, a heat supply unit, a first organic Rankine cycle power generation unit and a second organic Rankine cycle power generation unit, wherein the waste heat exchange unit carries out primary heat exchange on medium-temperature flue gas waste heat energy to heat conduction oil, the heat conduction oil is distributed to the heat supply unit and the first organic Rankine cycle power generation unit through the heat conduction oil distribution and control unit, the heat supply unit and the first organic Rankine cycle power generation unit work in parallel, and flue gas waste heat after heat exchange with the heat conduction oil enters the second organic Rankine cycle power generation unit to carry out secondary power generation. High-temperature heat is obtained through first-stage heat exchange, the electric load of a heat supply system is met preferentially through a heat conduction oil distribution and control system, the purpose of preferentially and stably supplying heat is achieved, and the residual heat is subjected to two-stage power generation through two organic Rankine cycle power generation systems, so that a better cogeneration proportion is achieved.)

1. A two-stage organic Rankine cycle combined heat and power system with preferential heat supply is characterized by comprising a waste heat exchange unit (1), a heat conduction oil distribution and control unit (2), a heat supply unit (3), a first organic Rankine cycle power generation unit (4) and a second organic Rankine cycle power generation unit (5);

the heat conduction oil distribution and control unit (2) comprises a computer (202), two heat conduction oil distribution electromagnetic valves (201), a first temperature sensor (203), a second temperature sensor (204) and a heat conduction oil pump (205); the inlet ends of two heat conduction oil distribution electromagnetic valves (201) are connected with a waste heat exchange unit (1), the outlet end of one heat conduction oil distribution electromagnetic valve (201) is connected with a heat supply unit (3), the outlet end of the other heat conduction oil distribution electromagnetic valve (201) is connected with a first organic Rankine cycle power generation unit (4), a computer (202) is respectively connected with a first temperature sensor (203) and a second temperature sensor (204), the first temperature sensor (203) is used for detecting the outlet temperature of heat conduction oil after heat exchange with flue gas, and the second temperature sensor (204) is used for detecting the temperature of the inlet of heat conduction oil before heat exchange with flue gas; after the heat conduction oil respectively passes through the heat supply unit (3) and the first organic Rankine cycle power generation unit (4), the heat conduction oil is converged and connected to a heat conduction oil inlet of the waste heat exchange unit (1) through a heat conduction oil pump (205);

the waste heat exchange unit (1) performs primary heat exchange on the waste heat energy of the medium-temperature flue gas to heat conduction oil, the heat conduction oil is distributed to the heat supply unit (3) and the first organic Rankine cycle power generation unit (4) through the heat conduction oil distribution and control unit (2), the heat supply unit (3) and the first organic Rankine cycle power generation unit (4) work in parallel, and the waste heat of the flue gas after heat exchange with the heat conduction oil enters the second organic Rankine cycle power generation unit (5) to perform secondary power generation.

2. The preferential heat supply two-stage organic Rankine cycle combined heat and power system according to claim 1, wherein the waste heat exchange unit (1) is provided with a flue gas heat exchanger (101), a heat conduction oil outlet end of the flue gas heat exchanger (101) is connected with inlet ends of two heat conduction oil distribution electromagnetic valves (201), and an outlet end of a heat conduction oil pump (205) is connected with a heat conduction oil inlet end of the flue gas heat exchanger (101).

3. The priority heating two-stage orc thermoelectric cogeneration system of claim 2, wherein said flue gas heat exchanger (101) is a plate heat exchanger.

4. The preferential heat supply two-stage organic Rankine cycle combined heat and power system according to claim 1, wherein the heat supply unit (3) is provided with a heat exchanger (301), the heat conduction oil distributed to the heat supply unit (3) by one heat conduction oil distribution solenoid valve (201) exchanges heat through the heat exchanger (301), and the outlet end of the heat exchanger (301) is connected to the heat conduction oil inlet of the heat exchange unit (1) through a heat conduction oil pump (205).

5. The priority heat supply two-stage organic Rankine cycle combined heat and power system according to claim 1, wherein the first organic Rankine cycle power generation unit (4) comprises a first evaporator (401), a first expander (402), a first condenser (403), a first cycle fluid pump (404), a first cycle fluid pump (405), and a first generator (406); the cold end of the first evaporator (401), the first expander (402), the hot end of the first condenser (403), the first liquid storage tank (404) and the first circulating working medium pump (405) are sequentially connected to form an organic working medium circulating loop; the first expander (402) is connected with a first generator (406) through a shaft connector to form a first expander generator set, a high-temperature fluid side inlet of the first evaporator (401) is connected with the heat-conducting oil distribution and control unit (2), and a low-temperature fluid side of the first condenser (403) is externally connected with a tap water supply end.

6. The priority heat supply two-stage organic Rankine cycle combined heat and power system according to claim 5, wherein the second organic Rankine cycle power generation unit (5) includes a second evaporator (501), a second expander (502), a second condenser (503), a second liquid storage tank (504), a second cycle fluid pump (505), and a second generator (506); the cold end of the second evaporator (501), the second expander (502), the hot end of the second condenser (503), the second liquid storage tank (504) and the second circulating working medium pump (505) are sequentially connected to form an organic working medium circulating loop; the second expander (502) is connected with a second generator (506) through a shaft connector to form a second expander generator set, the inlet of the high-temperature fluid side of the second evaporator (501) is connected with the waste heat exchange unit (1), and the low-temperature fluid side of the second condenser (503) is externally connected with a tap water supply end.

7. The priority heating two-stage organic Rankine cycle combined heat and power system according to claim 1 or 6, wherein the first organic Rankine cycle power generation unit (4) and the second organic Rankine cycle power generation unit (5) both employ R245fa as a circulating working medium.

8. The priority heating two-stage orc thermoelectric cogeneration system of claim 6, wherein the first expander (402) and the second expander (502) are both screw expanders.

9. The method for regulating and controlling the two-stage organic Rankine cycle combined heat and power system with preferential heat supply according to any one of claims 1 to 8, comprising the following steps of:

preferentially meeting the heat supply load: the method comprises the following steps that (1) heat conduction oil of a main part flows into a heat supply unit (3) according to heat supply requirements, and the rest heat conduction oil enters a first organic Rankine cycle power generation unit (4);

the flow of the heat conduction oil is confirmed by the heat conduction oil distribution and control unit (2): the computer (202) calculates according to the heat load of the heat supply section and the oil inlet temperature and the oil return temperature fed back by the first temperature sensor (203) and the second temperature sensor (204), and realizes control through the two heat conduction oil distribution electromagnetic valves (201);

secondary power generation: and the waste heat of the flue gas after heat exchange with the heat conduction oil enters a second organic Rankine cycle power generation unit (5) for secondary power generation.

10. The regulation and control method of the priority heat supply-based two-stage organic Rankine cycle combined heat and power system according to claim 9, wherein the waste heat exchange unit (1) performs primary utilization on flue gas, flue gas waste heat performs primary heat exchange with heat conduction oil through the waste heat exchange unit (101), and the heat conduction oil absorbs heat and then enters the heat conduction oil distribution and control unit (2);

when the temperature of the heat source is lower than 300 ℃, most energy of the heat source is recovered by the waste heat exchange unit (101), the temperature of the flue gas after heat exchange is low, the residual heat cannot be utilized, and the secondary organic Rankine cycle units are all closed;

when the temperature of a heat source is 300-600 ℃, the temperature of flue gas is high, the energy recovered at the first stage is used for cogeneration, and the residual heat is subjected to supplementary power generation through a secondary organic Rankine cycle unit.

Technical Field

The invention belongs to the technical field of energy, and relates to a two-stage organic Rankine cycle combined heat and power system with preferential heat supply and a regulation and control method.

Background

The industrial waste heat recovery and utilization has great significance, and the combined heat and power technology can convert part of heat energy into electric energy while recovering heat energy by utilizing heat exchange, and is a main process in waste heat recovery. The Organic Rankine Cycle (ORC) adopts low-boiling organic working media to carry out heat-power conversion, and has more advantages compared with the steam Rankine cycle in the aspect of recovering low-temperature waste heat below 200 ℃. And the ORC system has compact structure, convenient start and stop, good load adaptability and low maintenance cost. The ORC low-temperature waste heat power generation technology is relatively mature, and a plurality of application examples for recovering medium-low temperature heat energy by utilizing organic Rankine cycle are reported, such as organic Rankine cycle units for utilizing oilfield geothermal power generation and recovery power generation of waste heat flue gas of a cement kiln at about 150 ℃ and radiation waste heat of a cement kiln cylinder by adopting an organic working medium Rankine cycle system.

Most waste heat recovery systems of combined heat and power adopt a preferential power supply mode to ensure stable operation of an ORC system, which can cause heat supply fluctuation and cannot meet the heat supply requirement of specific change. In addition, the heat source of the flue gas may fluctuate in winter and summer, which requires a certain adjustment capability of the waste heat recovery system. However, no report is available on the prior waste heat recycling system that the prior waste heat recycling system can achieve the purpose of preferential heat supply by reasonably adjusting the heat source.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a two-stage organic Rankine cycle combined heat and power system for preferential heat supply, which can reasonably distribute heat sources for heat supply and power supply through a heat source regulation control system under the condition of heat source change according to heat supply requirements, so as to achieve the purpose of preferential heat supply.

In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:

the invention discloses a two-stage organic Rankine cycle combined heat and power system with preferential heat supply, which comprises a waste heat exchange unit, a heat conduction oil distribution and control unit, a heat supply unit, a first organic Rankine cycle power generation unit and a second organic Rankine cycle power generation unit, wherein the waste heat exchange unit is used for exchanging heat with the heat conduction oil distribution and control unit;

the heat conduction oil distribution and control unit comprises a computer, two heat conduction oil distribution electromagnetic valves, a first temperature sensor, a second temperature sensor and a heat conduction oil pump; the inlet ends of two heat conduction oil distribution electromagnetic valves are connected with the waste heat exchange unit, the outlet end of one heat conduction oil distribution electromagnetic valve is connected with the heat supply unit, the outlet end of the other heat conduction oil distribution electromagnetic valve is connected with the first organic Rankine cycle power generation unit, the computer is respectively connected with the first temperature sensor and the second temperature sensor, the first temperature sensor is used for detecting the outlet temperature of the heat conduction oil after heat exchange with the flue gas, and the second temperature sensor is used for detecting the temperature of the heat conduction oil before heat exchange with the flue gas; after the heat conduction oil respectively passes through the heat supply unit and the first organic Rankine cycle power generation unit, converging the heat conduction oil and connecting the heat conduction oil to a heat conduction oil inlet of the waste heat exchange unit through a heat conduction oil pump;

the waste heat exchange unit performs primary heat exchange on the waste heat energy of the medium-temperature flue gas to heat conduction oil, the heat conduction oil is distributed to the heat supply unit and the first organic Rankine cycle power generation unit through the heat conduction oil distribution and control unit, the heat supply unit and the first organic Rankine cycle power generation unit work in parallel, and the waste heat of the flue gas after heat exchange with the heat conduction oil enters the second organic Rankine cycle power generation unit to perform secondary power generation.

Preferably, the waste heat exchange unit is provided with a flue gas heat exchanger, a heat conduction oil outlet end of the flue gas heat exchanger is connected with inlet ends of the two heat conduction oil distribution electromagnetic valves, and an outlet end of the heat conduction oil pump is connected with a heat conduction oil inlet end of the flue gas heat exchanger.

Further preferably, the flue gas heat exchanger adopts a plate heat exchanger.

Preferably, the heat supply unit is provided with a heat exchanger, the heat conduction oil distributed to the heat supply unit by one of the heat conduction oil distribution solenoid valves exchanges heat through the heat exchanger, and the outlet end of the heat exchanger is connected to a heat conduction oil inlet of the heat exchange unit through a heat conduction oil pump.

Preferably, the first organic Rankine cycle power generation unit comprises a first evaporator, a first expander, a first condenser, a first circulating working medium pump and a first power generator; the cold end of the first evaporator, the first expander, the hot end of the first condenser, the first liquid storage tank and the first circulating working medium pump are sequentially connected to form an organic working medium circulating loop; the first expander is connected with a first generator through a shaft connector to form a first expander generator set, a high-temperature fluid side inlet of the first evaporator is connected with the heat-conducting oil distribution and control unit, and a low-temperature fluid side of the first condenser is externally connected with a tap water supply end.

Further preferably, the second organic rankine cycle power generation unit comprises a second evaporator, a second expander, a second condenser, a second liquid storage tank, a second circulating working medium pump and a second generator; the cold end of the second evaporator, the second expander, the hot end of the second condenser, the second liquid storage tank and the second circulating working medium pump are sequentially connected to form an organic working medium circulating loop; the second expander is connected with a second generator through a shaft connector to form a second expander generator set, a high-temperature fluid side inlet of the second evaporator is connected with the waste heat exchange unit, and a low-temperature fluid side of the second condenser is externally connected with a tap water supply end.

Preferably, the first organic Rankine cycle power generation unit and the second organic Rankine cycle power generation unit both adopt R245fa as the circulating working medium.

Further preferably, the first expander and the second expander are both screw expanders.

The invention also discloses a regulation and control method of the two-stage organic Rankine cycle combined heat and power system based on the preferential heat supply, which comprises the following steps:

preferentially meeting the heat supply load: the method comprises the following steps that (1) heat conduction oil of a main part flows into a heat supply unit according to heat supply requirements, and the rest heat conduction oil enters a first organic Rankine cycle power generation unit;

the flow of the heat conduction oil is confirmed by the heat conduction oil distribution and control unit: the computer calculates according to the heat load of the heat supply section and the oil inlet temperature and the oil return temperature fed back by the first temperature sensor and the second temperature sensor, and the control is realized through two heat conduction oil distribution electromagnetic valves;

secondary power generation: and the waste heat of the flue gas after heat exchange with the heat conduction oil enters a second organic Rankine cycle power generation unit for secondary power generation.

Preferably, the waste heat exchange unit is used for carrying out primary utilization on the flue gas, the flue gas waste heat is firstly subjected to primary heat exchange with the heat conduction oil through the waste heat exchange unit, and the heat conduction oil absorbs heat and then enters the heat conduction oil distribution and control unit;

when the temperature of the heat source is less than 300 ℃, most energy of the heat source is recovered by the waste heat exchange unit, the temperature of the flue gas after heat exchange is low, the residual heat cannot be utilized, and the secondary organic Rankine cycle units are all closed;

when the temperature of a heat source is 300-600 ℃, the temperature of flue gas is high, the energy recovered at the first stage is used for cogeneration, and the residual heat is subjected to supplementary power generation through a secondary organic Rankine cycle unit.

Compared with the prior art, the invention has the following beneficial effects:

the invention discloses a priority heat supply two-stage organic Rankine cycle combined heat and power system which comprises a waste heat exchange unit, a heat conduction oil distribution and control unit, a heat supply unit, a first organic Rankine cycle power generation unit and a second organic Rankine cycle power generation unit. High-temperature heat is obtained through first-stage heat exchange, the electric load of a heat supply system is met preferentially through a heat conduction oil distribution and control system, the purpose of preferentially and stably supplying heat is achieved, and the residual heat is subjected to two-stage power generation through two organic Rankine cycle power generation systems, so that a better cogeneration proportion is achieved. Therefore, the system can reasonably distribute the heat sources of the heat supply system and the power supply system through the heat source adjusting and controlling system under the condition of heat source change according to heat supply requirements, achieves the aim of preferential heat supply, and has three modes of heat supply, power supply and combined heat and power supply.

Furthermore, the organic Rankine cycle working medium is non-toxic, non-flammable, non-explosive, stable in chemical property and environment-friendly, and through analysis, R245fa is adopted by the two organic Rankine cycle power generation units as the working medium. The screw expansion machines are high in isentropic efficiency, good in dynamic balance, simple, reliable and free of wearing parts, and the two organic Rankine cycle power generation systems both adopt the screw expansion machines.

The regulation and control method based on the system has the advantages that: first, can select one-level or two-stage recycle according to the change of flue gas heat source, obtain the high temperature heat through one-level heat transfer, reach and preferentially satisfy the heat supply demand. Secondly, the heat load can be satisfied with the priority of heat fixed electricity according to the heat supply demand change. The heat conduction oil distribution and control system preferentially meets the electric load of the heat supply system, and the rest heat is generated by the two organic Rankine cycle power generation systems, so that the better heat and power combined supply proportion is realized.

Drawings

FIG. 1 is a schematic structural diagram of a two-stage organic Rankine cycle combined heat and power system with preferential heat supply according to the present invention;

wherein: the dotted line boxes are respectively: 1. a waste heat exchange unit; 2. a heat conducting oil distribution and control unit; 3. a heat supply unit; 4. a first organic rankine cycle power generation unit; 5. a second organic rankine cycle power generation unit;

specifically, the method comprises the following steps: 101. a flue gas heat exchanger; 201. a heat conducting oil distribution electromagnetic valve; 202. a computer; 203. a first temperature sensor; 204. a second temperature sensor; 205. a heat-conducting oil pump; 301. a heat exchanger; 401. a first evaporator; 402. a first expander; 403. a first condenser; 404. a first liquid storage tank; 405. a first circulating working medium pump; 406. a first generator; 501. a second evaporator; 502. a second expander; 503. a second condenser; 504. a second liquid storage tank; 505. a second circulating working medium pump; 506. a second generator.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The invention is described in further detail below with reference to the accompanying drawings:

referring to fig. 1, the invention discloses a two-stage organic rankine cycle cogeneration system for preferential heating, which comprises five subsystems: the system comprises a waste heat exchange unit 1, a heat conduction oil distribution and control unit 2, a heat supply unit 3, a first organic Rankine cycle power generation unit 4 and a second organic Rankine cycle power generation unit 5. The waste heat exchange unit 1 conducts primary heat exchange on the waste heat energy of the medium-temperature flue gas to heat conduction oil, the heat conduction oil is distributed to the heat supply unit 3 and the first organic Rankine cycle power generation unit 4 through the heat conduction oil distribution and control unit 2, the heat supply unit 3 and the first organic Rankine cycle power generation unit 4 work in parallel, and the waste heat of the flue gas after heat exchange with the heat conduction oil enters the second organic Rankine cycle power generation unit 5 to conduct secondary power generation.

The waste heat exchange unit 1 firstly exchanges heat with heat conduction oil through the flue gas heat exchanger 101 in a primary mode, the heat conduction oil absorbs heat and then enters the heat conduction oil distribution and control unit 2, and the flue gas heat exchanger 101 is a plate heat exchanger.

The heat supply unit 3 is provided with a heat exchanger 301, heat conduction oil distributed to the heat supply unit 3 by one of the heat conduction oil distribution electromagnetic valves 201 exchanges heat through the heat exchanger 301, and the outlet end of the heat exchanger 301 is connected to a heat conduction oil inlet of the heat exchange unit 1 through a heat conduction oil pump 205.

The first organic Rankine cycle power generation unit 4 comprises a first evaporator 401, a first expander 402, a first condenser 403, a first circulating medium pump 404, a first circulating medium pump 405 and a first generator 406; the cold end of the first evaporator 401, the first expander 402, the hot end of the first condenser 403, the first liquid storage tank 404 and the first circulating working medium pump 405 are connected in sequence to form an organic working medium circulating loop; the first expander 402 is connected with the first generator 406 through a shaft connector to form a first expander generator set, the high-temperature fluid side inlet of the first evaporator 401 is connected with the heat-conducting oil distribution and control unit 2, and the low-temperature fluid side of the first condenser 403 is connected with the external tap water supply end.

The second organic Rankine cycle power generation unit 5 comprises a second evaporator 501, a second expander 502, a second condenser 503, a second liquid storage tank 504, a second circulating working medium pump 505 and a second power generator 506; the cold end of the second evaporator 501, the hot end of the second expander 502, the hot end of the second condenser 503, the second liquid storage tank 504 and the second circulating working medium pump 505 are connected in sequence to form an organic working medium circulating loop; the second expander 502 is connected with a second generator 506 through a shaft connector to form a second expander generator set, the hot end of the second evaporator 501 is a flue gas waste heat source after heat exchange with heat conduction oil, and the low-temperature fluid side of the second condenser 503 is externally connected with a tap water supply end.

The waste heat exchange unit 1 is used for primary utilization of flue gas, flue gas waste heat is firstly subjected to primary heat exchange with heat conduction oil through the flue gas heat exchanger 101, and the heat conduction oil absorbs heat and then enters the heat conduction oil distribution and control system 2. When the temperature of the heat source is lower than 300 ℃, most energy of the heat source needs to be recovered by the flue gas heat exchanger, the temperature of the flue gas after heat exchange is lower, the residual heat is difficult to utilize, and the secondary organic Rankine cycle unit is closed. When the temperature of a heat source is higher than 300-600 ℃, the temperature of the flue gas from the waste heat recovery system is drier, and after the primary recovered energy is used for cogeneration, the residual heat can be supplemented for power generation through secondary organic Rankine cycle.

The heat conducting oil which can be distributed to obtain heat by the heat conducting oil distribution and control unit 2 enters the heat supply unit 3 and the first organic Rankine cycle unit 4, and the heat conducting oil distribution and control unit is composed of two heat conducting oil distribution electromagnetic valves 201, a computer 202, a first temperature sensor 203, a second temperature sensor 204 and a heat conducting oil pump 205. The first sensor 203 detects the outlet temperature after heat transfer oil and the flue gas exchange heat, and the second temperature sensor 204 detects the inlet temperature before heat transfer oil and the flue gas exchange heat. The computer 202 is an industrial control computer, which receives the temperature fed back by the temperature sensor and calculates the required heat transfer oil flow according to the heat supply demand. And finally, controlling the heat conduction oil distribution electromagnetic valve 201 to work, and distributing the heat conduction oil flow entering the heat supply unit 3 and the first organic Rankine cycle power generation unit 4.

The distribution and control strategy of the heat conduction oil distribution and control unit 2 is as follows: the heat supply load is preferably met, the heat conduction oil mainly flows into the heat supply unit 3, and the rest heat conduction oil enters the first organic Rankine cycle power generation unit 4. The flow of the heat conducting oil can be calculated by the computer 202 according to the heat load of the heat supply end and the oil inlet temperature and the oil return temperature fed back by the first temperature sensor and the second temperature sensor, and is controlled by the heat conducting oil distribution electromagnetic valve 201. Meanwhile, the computer 202 may also set a control strategy according to the temperature changes in different seasons to satisfy stable heat supply under the change of heat sources.

The heating system 3 provides stable heat energy mainly through a heat exchanger 301.

In the first organic rankine cycle power generation unit 4 and the second organic rankine cycle power generation unit 5 provided in this embodiment, the working medium sequentially flows through the first evaporator 401 or the second evaporator 501 for isobaric heating to obtain heat, the heated working medium enters the first expander 402 or the second expander 502 for adiabatic expansion to drive the first generator 406 or the second generator 506 to rotate for power generation, the expanded working medium enters the first condenser 403 or the second condenser 503 for isobaric heat release, the heat is transferred to the condensed water and then enters the first liquid storage tank 404 or the second liquid storage tank 504, and finally the condensed water is adiabatically compressed by the first cyclic working medium pump 405 or the second cyclic working medium pump 505 and returns to the first evaporator 401 or the second evaporator 505.

In the two organic Rankine cycle power generation units of the embodiment, R245fa is adopted as a cycle working medium, when the temperature of a heat source is 150-250 ℃, the evaporation temperature is 100-150 ℃, the condensation temperature is 35-50 ℃, the superheat degree is 1-5 ℃, the supercooling degree is 1-20 ℃, the temperature difference of a node is 5-20 ℃, the isentropic efficiency of the expansion machine is determined by the performance of the expansion machine and is about 60-85%, and the efficiency can reach 70% by adopting a screw type expansion machine. Under the parameter, the efficiency of the organic Rankine cycle power generation system can reach about 10%.

The embodiment can select one-stage or two-stage recycling according to the change of the flue gas heat source. Wherein, the first-stage heat exchange obtains stable high-temperature heat, and the heat supply requirement is preferentially met. Meanwhile, the heat load can be met preferentially by fixing the electricity with heat according to the change of heat supply requirements. The heat conduction oil distribution and control system preferentially meets the electric load of the heat supply system, and the rest heat is generated by the two organic Rankine cycle power generation systems, so that the better heat and power combined supply proportion is realized.

The system can reasonably distribute the heat sources of the heat supply system and the power supply system through the heat source adjusting and controlling system under the condition of heat source change according to heat supply requirements, achieves the purpose of preferential heat supply, and has three modes of heat supply, power supply and combined heat and power supply:

when the heat supply demand is greater than or equal to the recoverable energy of the flue gas, the system is in a heat supply mode: the first organic Rankine cycle power generation unit and the second organic Rankine cycle power generation unit do not work, and the heat conduction oil distribution and control unit sends all hot oil which exchanges heat with the flue gas to the heat supply system for heat supply.

When the heat supply demand is small, the system is in a combined heat and power mode: when the temperature of a heat source is lower than 300 ℃, primary utilization is carried out through the waste heat exchange unit, the heat conduction oil distribution and control unit regulates and controls the heat supply system and the first organic Rankine cycle power generation unit to carry out combined heat and power supply, and the secondary organic Rankine cycle unit is closed; when the temperature of a heat source is 300-600 ℃, after the primary recovered energy is used for cogeneration, the residual heat is subjected to supplementary power generation through a secondary organic Rankine cycle unit.

Under the condition of no heat supply requirement, the system is in a power supply mode: and when the temperature of the heat source is 300-600 ℃, performing cyclic power generation through two-stage organic Rankine cycle. When the temperature of the heat source is less than 300 ℃, the primary heat exchange unit can be closed, and the flue gas is directly introduced into the second organic Rankine cycle power generation unit for power supply.

The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.