阅读说明：本技术 一种双背压超临界二氧化碳多联产系统及运行方法 (Double-backpressure supercritical carbon dioxide poly-generation system and operation method ) 是由 刘明 孙瑞强 杨凯旋 刘继平 邢秦安 严俊杰 于 2020-11-25 设计创作，主要内容包括：基于超临界二氧化碳动力循环实现热电联产具有广阔的发展前景,但临界压力附近的二氧化碳放热曲线供热的匹配性较差,不适合直接用于供热。本发明提出一种双背压超临界二氧化碳多联产系统及运行方法,该系统主要包括透平、两级主压缩机、再压缩机、多级回热器,冷却器和锅炉构成的发电低背压回路；以及透平抽气经两级回热器放热后用以热网供热的高背压回路。该系统采用超临界二氧化碳动力循环发电提高发电效率,采用透平处压力较高的抽气为热网供热,同时为用户提供热、电两种能源。同时,可以通过调整抽气比例,满足不同的供热负荷需求,提高机组的运行灵活性。(The method for realizing cogeneration based on supercritical carbon dioxide power circulation has a wide development prospect, but the carbon dioxide heat release curve near the critical pressure has poor heat supply matching performance, and is not suitable for being directly used for heat supply. The invention provides a double-backpressure supercritical carbon dioxide poly-generation system and an operation method thereof, wherein the system mainly comprises a turbine, a two-stage main compressor, a recompressor, a multi-stage heat regenerator, a cooler and a power generation low-backpressure loop formed by a boiler; and the turbine exhaust is used for a high back pressure loop for supplying heat for a heat supply network after being released by the two-stage heat regenerator. The system adopts supercritical carbon dioxide power cycle power generation to improve the power generation efficiency, adopts the air exhaust with higher pressure at the turbine to supply heat for a heat supply network, and simultaneously provides two energy sources of heat and electricity for users. Meanwhile, different heat supply load requirements can be met by adjusting the air exhaust proportion, and the operation flexibility of the unit is improved.)

1. A double-backpressure supercritical carbon dioxide poly-generation system is characterized in that: the boiler comprises a boiler (1), wherein a working medium outlet of the boiler (1) is connected with a working medium inlet of a turbine (2), an exhaust port of the turbine (2) is connected with a heat regenerator (32) No. 2, a heat regenerator (33) No. 3 and a heat regenerator (34) No. 4 in sequence, a heat outlet of the heat regenerator (34) No. 4 is connected with a working medium inlet of a precooler (7), a working medium outlet of the precooler (7) is connected with an inlet of a front main compressor (4), an outlet of the front main compressor (4) is connected with a working medium inlet of an intermediate cooler (9), a working medium outlet of the intermediate cooler (9) is connected with an inlet of a main compressor (6), an outlet of the main compressor (6) is connected with a heat regenerator (34) No. 4, a heat regenerator (33) No. 3, a heat regenerator (32) No. 2 and a cold side of a heat regenerator (31) No. 1 in sequence, and a working medium;

a working medium pumping hole of the turbine (2) is sequentially connected with the heat regenerator (31) No. 1, the heat regenerator (35) No. 5 and the hot side of the heat supply network heater (8), and the outlet of the hot side of the heat supply network heater (8) is connected with the outlet of the front main compressor (4);

the cold side outlet of the No. 4 regenerator (34) is connected with the cold side inlet of the No. 5 regenerator (35), and the cold side outlet of the No. 5 regenerator (35) is connected with the cold side outlet of the No. 2 regenerator (32);

the cooling water inlet and outlet of the heating network heater (8) are connected with the heating network, and the cooling water inlet and outlet of the precooler (7) and the precooler (9) are connected with the cooling water system.

2. The dual back pressure supercritical carbon dioxide polygeneration system of claim 1, wherein: the outlet of the No. 4 heat regenerator (34) is also connected with the working medium inlet of the recompressor (5), and the working medium outlet of the recompressor (5) is connected with the cold side inlet of the No. 2 heat regenerator (32).

3. The dual back pressure supercritical carbon dioxide polygeneration system of claim 1, wherein: the pressure of the exhaust port of the turbine (2) is 7.8MPa-8.6 MPa.

4. The dual back pressure supercritical carbon dioxide polygeneration system of claim 1, wherein: the pressure of the air extraction opening of the turbine (2) is 10MPa-15.0 MPa.

5. The dual back pressure supercritical carbon dioxide polygeneration system of claim 1, wherein: the outlet pressure of the preposed main compressor (4) is 9.5MPa-14.5 MPa.

6. The dual back pressure supercritical carbon dioxide polygeneration system of claim 1, wherein: the working medium outlet temperature of the precooler (7) and the intermediate cooler (9) is 33-38 ℃.

7. The method of operating a dual back pressure supercritical carbon dioxide polygeneration system of any of claims 1 to 6, wherein: after the pressure of supercritical carbon dioxide is increased in a preposed main compressor (4), the supercritical carbon dioxide is cooled in an intercooler (9), then the supercritical carbon dioxide is increased in a main compressor (6), then the supercritical carbon dioxide is subjected to heat absorption in a heat regenerator (34) No. 4, a heat regenerator (33) No. 3, a heat regenerator (32) No. 2, a heat regenerator (31) No. 1 and a boiler (1) in sequence to form high-temperature high-pressure carbon dioxide, then the high-temperature high-pressure carbon dioxide enters a turbine (2) to do work, exhaust gas of the turbine (2) is subjected to heat release in the heat regenerator (32) No. 2, the heat regenerator (33) No. 3 and the heat regenerator (34) No. 4 in sequence and then is divided into two strands, one strand is subjected to pressure increase by a recompressor (5) and then is merged into an inlet of the heat regenerator (32), and;

after high-temperature and high-pressure carbon dioxide enters the turbine (2) to do work, part of the high-temperature and high-pressure carbon dioxide is extracted from an extraction opening of the turbine (2), and is converged into a cold working medium inlet of an intercooler (9) after heat release of a No. 1 heat regenerator (31), a No. 5 heat regenerator (35) and a heat supply network heater (8) in sequence, the temperature of a supercritical carbon dioxide working medium entering the heat supply network heater (8) is adjusted by adjusting the extraction proportion of the part of the high-temperature and high-pressure carbon dioxide, different heat supply load requirements are met, and;

a part of working medium is shunted at the cold side outlet of the No. 4 regenerator (34) and is heated by the No. 5 regenerator (35) and then flows into the cold side working medium inlet of the No. 1 regenerator (31).

Technical Field

The invention belongs to the field of cogeneration, and particularly relates to a double-backpressure supercritical carbon dioxide poly-generation system and an operation method thereof.

Background

The realization of cogeneration and the simultaneous satisfaction of the electricity and heat load requirements of the society are one of the main directions of the development of the future power generation system. Fossil energy resources in China are endowed with the problems of rich coal, poor oil, little gas, resource deficiency and serious environmental pollution, and the development of cogeneration is one of the most effective means for saving energy, reducing emission and improving the energy utilization efficiency of a power station; meanwhile, the combined heat and power generation can save land and improve the benefit. In recent years, the cogeneration of heat and power in China enters a rapid development period.

The supercritical carbon dioxide power cycle has the advantages of high energy density, compact system structure, high cycle efficiency and the like, has good heat source matching performance, can be widely applied to the fields of solar energy, nuclear power, thermal power and the like, and is a novel power cycle form expected to replace water working medium Rankine cycle in the future. Therefore, the method has wide development prospect for realizing cogeneration based on supercritical carbon dioxide power circulation.

At present, research on supercritical carbon dioxide circulation is mainly carried out on a pure power generation system, and relatively few researches on cogeneration are carried out. The design of the existing supercritical carbon dioxide cogeneration system takes exhaust gas at the outlet of a turbine as a heating source for returning water of a heat supply network, or integrates an absorption heat pump on the basis. However, the pressure of the exhaust gas at the outlet of the turbine is near the critical pressure of the carbon dioxide, and the carbon dioxide heat release curve in the parameter interval has poor heat supply matching performance and is not suitable for being directly used for heat supply, as shown in fig. 1.

Disclosure of Invention

In order to overcome the problems in the prior art, the invention aims to provide a double-backpressure supercritical carbon dioxide poly-generation system and an operation method thereof. Through the grading optimization of the heat regeneration system, the high and low back pressure loops are reasonably coupled, and the energy utilization rate of the supercritical carbon dioxide system is greatly improved.

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

a double-backpressure supercritical carbon dioxide poly-generation system comprises a boiler 1, wherein a working medium outlet of the boiler 1 is connected with a working medium inlet of a turbine 2, an exhaust port of the turbine 2 is sequentially connected with hot sides of a heat regenerator 32, a heat regenerator 33 and a heat regenerator 34 of the No. 2, a hot side outlet of the heat regenerator 34 of the No. 4 is connected with a working medium inlet of a precooler 7, a working medium outlet of the precooler 7 is connected with an inlet of a front main compressor 4, an outlet of the front main compressor 4 is connected with a working medium inlet of an intercooler 9, a working medium outlet of the intercooler 9 is connected with an inlet of a main compressor 6, an outlet of the main compressor 6 is sequentially connected with a cold side 31 of the heat regenerator 34 of the No. 4, the heat regenerator 33 of the No. 3, the heat regenerator 32 and the heat regenerator of the No. 1;

a working medium pumping hole of the turbine 2 is sequentially connected with a heat regenerator 31 No. 1, a heat regenerator 35 No. 5 and the hot side of the heat supply network heater 8, and an outlet of the hot side of the heat supply network heater 8 is connected with an outlet of the front main compressor 4;

the cold side outlet of the No. 4 regenerator 34 is connected with the cold side inlet of the No. 5 regenerator 35, and the cold side outlet of the No. 5 regenerator 35 is connected with the cold side outlet of the No. 2 regenerator 32;

the cooling water inlet and outlet of the heating network heater 8 are connected with the heating network, and the cooling water inlet and outlet of the precooler 7 and the precooler 9 are connected with the cooling water system.

The outlet of the No. 4 heat regenerator 34 is also connected with the working medium inlet of the recompressor 5, and the working medium outlet of the recompressor 5 is connected with the cold side inlet of the No. 2 heat regenerator 32.

The pressure of the exhaust port of the turbine 2 is 7.8MPa-8.6 MPa.

The pressure of the air extraction opening of the turbine 2 is 10MPa-15.0 MPa.

The outlet pressure of the preposed main compressor 4 is 9.5MPa-14.5 MPa.

The temperature of the working medium outlet of the precooler 7 and the intermediate cooler 9 is 33-38 ℃.

The operation method of the double-backpressure supercritical carbon dioxide poly-generation system comprises the steps that supercritical carbon dioxide is subjected to pressure boosting in a front main compressor 4, then is cooled in an intercooler 9, is subjected to pressure boosting in a main compressor 6, and then is subjected to heat absorption in a heat regenerator 34 No. 4, a heat regenerator 33 No. 3, a heat regenerator 32 No. 2, a heat regenerator 31 No. 1 and a boiler 1 in sequence to form high-temperature high-pressure carbon dioxide, then the high-temperature high-pressure carbon dioxide enters a turbine 2 to do work, exhaust of the turbine 2 is subjected to heat release in the heat regenerators 32 No. 2, the heat regenerator 33 No. 3 and the heat regenerator 34 No. 4 in sequence and then is divided into two strands, one strand is subjected to pressure boosting by a recompressor 5 and then is converged into an inlet of the heat regenerator 32 No. 2, and the other strand enters the front main compressor 4;

after high-temperature and high-pressure carbon dioxide enters the turbine 2 to do work, part of the high-temperature and high-pressure carbon dioxide is extracted from an extraction opening of the turbine 2, and is converged into a cold working medium inlet of the intercooler 9 after heat release of the No. 1 heat regenerator 31, the No. 5 heat regenerator 35 and the heat supply network heater 8 in sequence, the temperature of the supercritical carbon dioxide working medium entering the heat supply network heater 8 is adjusted by adjusting the extraction proportion of the part of the high-temperature and high-pressure carbon dioxide, so that different heat supply load requirements are met, the operation flexibility of a unit;

the part of working medium which is shunted at the cold side outlet of the No. 4 regenerator 34 is heated by the No. 5 regenerator 35 and then is gathered at the cold side working medium inlet of the No. 1 regenerator 31.

Compared with the prior art, the invention has the following advantages:

(1) the invention provides a double-backpressure supercritical carbon dioxide poly-generation system, which can be used for greatly improving the energy utilization rate of the system by reasonably coupling high and low backpressure loops through the grading optimization of a heat regeneration system, and the energy utilization rate can reach more than 60%.

(2) The invention adopts the supercritical carbon dioxide with higher pressure to pump air to supply heat for the heat supply network, avoids the area with poorer heat release curve and reasonably utilizes the energy of each temperature area of the system;

(3) the invention can meet different heat supply load requirements by adjusting the air extraction proportion at the transparent position, and improves the operation flexibility of the unit.

Drawings

Fig. 1 is a temperature-enthalpy diagram of supercritical carbon dioxide.

FIG. 2 is a schematic diagram of a dual back pressure supercritical carbon dioxide polygeneration system of the present invention.

FIG. 3 is a graph of regenerator temperature for the polygeneration system of the present invention.

In the figure: boiler 1, turbine 2, heat regenerator No. 1 at 31, heat regenerator No. 2 at 32, heat regenerator No. 3 at 33, heat regenerator No. 4 at 34, heat regenerator No. 5 at 35, front main compressor at 4, re-compressor at 5, main compressor at 6, precooler at 7, heating network heater at 8, and intercooler at 9.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Principle of operation

The carbon dioxide heat release curve near the critical pressure has poor heat supply matching performance and is not suitable for directly supplying heat, as shown in figure 1. Therefore, the invention provides a double-backpressure supercritical carbon dioxide poly-generation system and an operation method. The low back pressure loop of the system is a power generation system with supercritical carbon dioxide recompression coupled with main compressor intercooling; the high back pressure loop adopts the air extraction heat supply with higher pressure (10-15MPa) at the turbine, and the air extraction temperature is too high, so the air is cooled by the two-stage heat regenerator and then is sent to the heat supply network heat regenerator to release heat, and the carbon dioxide working medium in the area has a good heat release curve. The working medium discharged by the heat supply network heat regenerator is converged into the inlet of the intercooler. Meanwhile, the temperatures of all the shunting points and the sink points are matched through the grading optimization of the heat recovery system, the cascade utilization of the exhaust heat is realized, and high and low back pressure loops are reasonably coupled, as shown in fig. 3. The system can meet the heat supply requirements of different loads by adjusting the air extraction proportion at the transparent position.

Meanwhile, due to the arrangement of the No. 1 heat regenerator 31, the temperature of the supercritical carbon dioxide working medium entering the boiler can be increased, and the irreversible loss of heat exchange is reduced. The invention innovatively provides high-back-pressure heat supply, avoids the area with a poor carbon dioxide heat release curve, and simultaneously adopts the coupling optimization of the processes of intermediate cooling, hot end-heat regeneration-heat release of the main compressor, thereby greatly improving the energy utilization rate of the supercritical carbon dioxide system. The construction and operation of the present invention will now be described in detail.

As shown in fig. 2, the double-back-pressure supercritical carbon dioxide poly-generation system comprises a boiler 1, wherein a working medium outlet of the boiler 1 is connected with a working medium inlet of a turbine 2, an exhaust port of the turbine 2 is sequentially connected with hot sides of a heat regenerator 32, a heat regenerator 33 and a heat regenerator 34 4, a hot side outlet of the heat regenerator 34 4 is connected with a working medium inlet of a precooler 7, a working medium outlet of the precooler 7 is connected with an inlet of a front main compressor 4, an outlet of the front main compressor 4 is connected with a working medium inlet of an intercooler 9, a working medium outlet of the intercooler 9 is connected with an inlet of a main compressor 6, an outlet of the main compressor 6 is sequentially connected with cold sides of the heat regenerator 34, the heat regenerator 33, the heat regenerator 32 and the heat regenerator 31 1, and a cold side outlet of the heat regenerator 31 1 is connected with the working medium inlet of the; a working medium pumping hole of the turbine 2 is sequentially connected with a heat regenerator 31 No. 1, a heat regenerator 35 No. 5 and the hot side of the heat supply network heater 8, and an outlet of the hot side of the heat supply network heater 8 is connected with an outlet of the front main compressor 4; the cold side outlet of the No. 4 regenerator 34 is connected with the cold side inlet of the No. 5 regenerator 35, and the cold side outlet of the No. 5 regenerator 35 is connected with the cold side outlet of the No. 2 regenerator 32; the cooling water inlet and outlet of the heating network heater 8 are connected with the heating network, and the cooling water inlet and outlet of the precooler 7 and the precooler 9 are connected with the cooling water system.

As a preferred embodiment of the invention, the outlet of the No. 4 regenerator 34 is also connected with the working medium inlet of the recompressor 5, and the working medium outlet of the recompressor 5 is connected with the cold side inlet of the No. 2 regenerator 32, so that the heat exchange 'pinch' problem of the No. 3 regenerator 33 and the No. 4 regenerator 34 can be avoided by adopting the split-flow recompression circulation mode, and the circulation efficiency can be improved.

As a preferred embodiment of the invention, the pressure of the exhaust port of the turbine 2 is 7.8MPa-8.6MPa, so that the pressure of the working medium inlet of the front main compressor 4 can be maintained above a critical point, the whole circulation is kept in a supercritical state, and the output power of the turbine 2 can be improved.

As the preferred embodiment of the invention, the pressure of the air extraction opening of the turbine 2 is 10MPa-15.0MPa, thus the air extraction with higher pressure is adopted to supply heat to the heat supply network, the parameter area with poorer heat release curve can be avoided, and the reasonable utilization of heat energy is realized.

As a preferred embodiment of the invention, the outlet pressure of the preposed main compressor 4 is 9.5MPa-14.5MPa, so that a large pressure difference can be avoided when two working mediums are gathered.

As a preferred embodiment of the invention, the temperature of the working medium outlet of the precooler 7 and the intercooler 9 is 33-38 ℃, so that the temperature of the working medium at the inlet of the preposed main compressor 4 and the main compressor 6 can be maintained above the critical point, and the whole cycle is kept in a supercritical state.

The invention relates to an operation method of a double-backpressure supercritical carbon dioxide poly-generation system, after the supercritical carbon dioxide is boosted in a preposed main compressor 4, the supercritical carbon dioxide is cooled in an intercooler 9, then the supercritical carbon dioxide is boosted in a main compressor 6, then the supercritical carbon dioxide is subjected to heat absorption in a No. 4 heat regenerator 34, a No. 3 heat regenerator 33, a No. 2 heat regenerator 32, a No. 1 heat regenerator 31 and a boiler 1 in sequence to become high-temperature high-pressure carbon dioxide, then the high-temperature high-pressure carbon dioxide enters a turbine 2 to do work, the exhaust gas of the turbine 2 is subjected to heat release in the No. 2 heat regenerator 32, the No. 3 heat regenerator 33 and the No. 4 heat regenerator 34 in sequence and then is divided into two strands, one strand is subjected to pressure boosting by a recompressor 5 and then is converged into an inlet of the No. 2; after high-temperature and high-pressure carbon dioxide enters the turbine 2 to do work, part of the high-temperature and high-pressure carbon dioxide is extracted from an extraction opening of the turbine 2, and is converged into a cold working medium inlet of the intercooler 9 after heat release of the No. 1 heat regenerator 31, the No. 5 heat regenerator 35 and the heat supply network heater 8 in sequence, and the temperature of the supercritical carbon dioxide working medium entering the heat supply network heater 8 is adjusted by adjusting the extraction proportion of the part of the high-temperature and high-pressure carbon dioxide, so that different heat supply load requirements are met; the part of working medium which is shunted at the cold side outlet of the No. 4 regenerator 34 is heated by the No. 5 regenerator 35 and then is gathered at the cold side working medium inlet of the No. 1 regenerator 31.