阅读说明：本技术 一种光热低温发电系统及其控制方法 (Photo-thermal low-temperature power generation system and control method thereof ) 是由 常波 杨建中 南莉莉 于 2019-10-18 设计创作，主要内容包括：本发明提供了一种光热低温发电系统及其控制方法,包括光热循环系统和第一有机工质循环系统；第一有机工质循环系统外还设置第二工质循环系统,第二工质循环系统包括第二高压仓、压缩机、汽液分离装置,高压仓至汽轮机之间的第四管路上设置有与第二高压仓连通的第二工质进口,高压仓出口与第二工质进口之间的第四管路上设置单向阀；冷凝器与工质泵之间位于第六管路上设置气液分离器。本发明是利用低温有机工质做温度衬托基质,采用混合工质能够有效的解决工质在输送过程中比热容低,难以保持临界温度、工作不稳定的问题。混合系统由原来低温中压变为低温高压或低温超高压系统,单台机组发电功率有显著增加,有利于减少加热系统的成本。(The invention provides a photo-thermal low-temperature power generation system and a control method thereof, wherein the photo-thermal low-temperature power generation system comprises a photo-thermal circulation system and a first organic working medium circulation system; a second working medium circulating system is arranged outside the first organic working medium circulating system and comprises a second high-pressure bin, a compressor and a vapor-liquid separation device, a second working medium inlet communicated with the second high-pressure bin is arranged on a fourth pipeline between the high-pressure bin and the steam turbine, and a one-way valve is arranged on the fourth pipeline between an outlet of the high-pressure bin and the second working medium inlet; and a gas-liquid separator is arranged on the sixth pipeline between the condenser and the working medium pump. The invention uses low-temperature organic working medium as temperature-contrast medium, and adopts mixed working medium to effectively solve the problems of low specific heat capacity, difficulty in maintaining critical temperature and unstable work of the working medium in the conveying process. The hybrid system is changed into a low-temperature high-pressure or low-temperature ultrahigh-pressure system from the original low-temperature medium-pressure system, the power generation power of a single unit is obviously increased, and the cost of a heating system is favorably reduced.)

1. A photo-thermal low-temperature power generation system comprises a photo-thermal circulation system and a first organic working medium circulation system; the photo-thermal circulation system comprises a circulation loop formed by sequentially connecting a tubular heat collection field (1), a heat exchanger (6) with a first organic working medium arranged inside and a pump (32), wherein the heat exchanger (6) heats and vaporizes the first organic working medium and then inputs the first organic working medium into the first organic working medium circulation system; the first organic working medium circulating system comprises a working medium circulating loop formed by sequentially connecting a high-pressure bin (8), a steam turbine (16), a condenser (21) and a working medium pump (29), and is characterized in that: the first organic working medium circulating system is also provided with a second working medium circulating system, the second working medium circulating system comprises a second high-pressure bin (9) and a compressor (15), the compressor (15) conveys a second working medium to the second high-pressure bin (9) through a seventh pipeline (28), a fourth pipeline (13) between the high-pressure bin (8) and a steam turbine (16) is provided with a second working medium inlet (11) communicated with the second high-pressure bin (9), the second working medium inlet (11) is externally provided with a flow regulating valve (12), the second high-pressure bin (9) is connected with the flow regulating valve (12) through a fifth pipeline (14), the high-pressure bin (8) comprises a high-pressure bin outlet (10), and the fourth pipeline (13) between the high-pressure bin outlet (10) and the second working medium inlet (11) is provided with a one-way valve (34); the condenser (21) and the working medium pump (29) are positioned on a sixth pipeline (22) and are provided with a gas-liquid separator (25), the gas-liquid separator (25) comprises a mixed organic working medium inlet (24), a first organic working medium outlet (26) and a second working medium outlet (23), the mixed organic working medium inlet (24) is connected with the sixth pipeline (22), the first organic working medium outlet (26) is connected with the working medium pump (29), the second working medium outlet (23) is connected with the compressor (15) through an eighth pipeline (20), and the second working medium is compressed to a gas storage tank (27) and is connected into a working medium circulation loop.

2. The photothermal low temperature power generation system according to claim 1, wherein: the first organic working medium is R134a, and the second working medium is CO2 or N2.

3. The photothermal low temperature power generation system according to claim 1, wherein: the tubular heat collection field (1) is communicated with the heat storage tank (3) through a first pipeline (2), and the heat storage tank (3) is communicated with the heat exchanger (6) through a second passage (4).

4. The photothermal low temperature power generation system according to claim 1, wherein: and the position of a second working medium inlet (11) on the fourth pipeline (13) is arranged at one end close to the high-pressure bin outlet (10).

5. The photothermal low temperature power generation system according to claim 1, wherein: an air storage tank (27) is arranged between the second high-pressure bin (9) and the compressor (15), and a secondary compressor (30) is arranged between the second high-pressure bin (9) and the air storage tank (27).

6. A photothermal low temperature power generation system according to claim 1 or 3, wherein: the heat storage tank (4) is still provided with a secondary heating pipeline (7) which is respectively connected to the pump (32) through the high-pressure bin (8) and the second high-pressure bin (9) to recover the tubular heat collection field (1), and the front end of the secondary heating pipeline (7) is provided with a switching valve (5) for switching the heating pipelines corresponding to the secondary heating pipe (7) and the heat exchanger (6).

7. The photothermal low temperature power generation system according to claim 1, wherein: an auxiliary heat source (33) is further arranged outside the tubular heat collection field (1), one end of the auxiliary heat source (33) is communicated with the tubular heat collection field (1), the other end of the auxiliary heat source (33) is communicated with the pump (32), and the auxiliary heat source (33) adopts a heat supply mode of industrial low-temperature waste heat or a geothermal well.

8. The photothermal low temperature power generation system according to claim 1, wherein: still be provided with low temperature heat storage tank (31) on the pipeline between heat exchanger (6) and tubular thermal-arrest field (1), low temperature heat storage tank (31) are close to the one end of heat exchanger (6).

9. The control method of a photothermal low temperature power generation system according to claim 1 or 2, comprising a photothermal heat storage mode and a first organic working medium circulation mode, characterized by comprising the steps of:

(1) in the photo-thermal heat storage mode, solar heat is collected by the tubular heat collection field (1), and after water absorbs heat and is heated to a preset temperature to become hot water, the hot water enters the heat storage tank (3) to be stored, so that the photo-thermal heat storage is completed. Hot water is shunted by a switching valve (5) and enters a heat exchanger (6) and a tube bundle inside the heat exchanger for heat exchange, so that a first organic working medium is heated to obtain temperature rise and vaporization, the temperature rise is 56-85 ℃, the pressure is 1.5-2.9 MPa, and water after heat exchange is recovered to a tubular heat collection field (1) for photo-thermal heat storage again;

(2) under the first organic working medium circulation mode, the switching valve (5) switches the secondary heating pipeline (7) to perform compensation heating on the first organic working medium in the high-pressure bin (8), and the first organic working medium in the high-pressure bin (8) is conveyed to the fourth pipeline (13); under a second working medium circulation mode, a switching valve (5) switches a secondary heating pipeline (7) to perform compensation heating on a second working medium in a second high-pressure bin (9), the temperature of the temperature rise is 30-70 ℃, the pressure is 7-10 MPa, the second working medium in a gas storage tank (27) enters the second high-pressure bin (9) from a secondary compressor (30), enters a fourth pipeline (13) from a fifth pipeline (15) through a flow regulating valve (12) to be mixed with the first organic working medium to form a mixed organic working medium, the mixed organic working medium is conveyed to a power generation system, enters a steam turbine (16) to perform expansion work, and outputs electric energy to a power transmission and transformation grid;

(3) the mixed organic working medium after expanding to do work and release energy is cooled by a condenser (21), the separated first organic working medium is recycled to a heat exchanger (6) by a working medium pump (29) to be circulated after passing through a gas-liquid separator (25), and the second working medium is pressurized to supercritical pressure after passing through a compressor (15), a gas storage tank (27) and a secondary compressor (30) and enters a second high-pressure bin (9) again to be circulated.

10. A photothermal low temperature power generation system according to claim 9, wherein: the temperature of the first organic working medium in the step (1) is 70 ℃, and the pressure is 2.1 MPa; the temperature of the second working medium in the step (2) is 30 ℃, and the pressure is 7.1 MPa.

Technical Field

The invention relates to the technical field of photo-thermal power generation, in particular to a photo-thermal low-temperature power generation system and a control method thereof.

Background

The photo-thermal power generation is to obtain heat energy by utilizing solar energy, and then obtain heat energy by absorbing the heat energy by using refrigerants such as low-temperature environment-friendly organic working media and the like, and convert the heat energy into mechanical power to do work and output electric energy through heating and vaporization. However, the situation that the pressure of the organic working medium is not ideal when the organic working medium is heated in solar photo-thermal low-temperature power generation generally exists, and the problems are that: 1. the design adopts simple substance organic working medium gas, and because the working is carried out under the low temperature condition, the pressure is limited to a certain extent, the molecular particles in unit volume are large in quantity and small in quantity, the expansion rate is low, and the power generation power of a steam turbine is low; 2. in order to obtain larger power, only a unit with smaller power can be adopted to form a small unit group for generating electricity, so that the defects that the area of a factory building and the input amount of equipment are increased, the heat consumption is increased, the maintenance management amount is increased and the like are caused; 3. the basic input temperature design point is adjusted, so that the basic pressure can be improved, but the total amount of a heat source, the temperature grade and the application range of the organic working medium are increased invisibly.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention provides a mixed gas input mode for photo-thermal low-temperature power generation, which can generate ultrahigh pressure to push machinery to do work under a certain temperature condition, and the mixed mode can also effectively solve the problems that the critical temperature is difficult to maintain and the work is unstable in the process of conveying working media.

The invention is realized by the following technical scheme: a photo-thermal low-temperature power generation system comprises a photo-thermal circulation system and a first organic working medium circulation system; the photo-thermal circulation system comprises a circulation loop formed by sequentially connecting a tubular heat collection field, a heat exchanger internally provided with a first organic working medium and a pump, wherein the heat exchanger enables the first organic working medium to be heated and vaporized and inputs the first organic working medium into the first organic working medium circulation system for power generation; the first organic working medium circulating system comprises an organic working medium circulating loop formed by sequentially connecting a high-pressure bin, a steam turbine, a condenser and a working medium pump. The first organic working medium circulation system is also provided with a second working medium circulation system, the second working medium circulation system comprises a second high-pressure bin, a compressor and a vapor-liquid separation device, the compressor conveys a second working medium to the second high-pressure bin through a seventh pipeline, a fourth pipeline between the high-pressure bin and the steam turbine is provided with a second working medium inlet communicated with the second high-pressure bin, a flow regulating valve is arranged outside the second working medium inlet, the second high-pressure bin is connected with the flow regulating valve through a fifth pipeline, the high-pressure bin comprises a high-pressure bin outlet, and a check valve is arranged on the fourth pipeline between the high-pressure bin outlet and the second working medium inlet; the condenser is connected with the working medium pump through a sixth pipeline, the first organic working medium outlet is connected with the working medium pump, the second working medium outlet is connected with the compressor through an eighth pipeline, and the second working medium is compressed to the gas storage tank and connected into the working medium circulation loop.

In the above scheme, the first organic working medium is R134a, and the second organic working medium is CO₂Or N₂。

In the above scheme, the tubular heat collection field is communicated with the heat storage tank through a first pipeline, and the heat storage tank is communicated with the heat exchanger through a second passage.

In the above scheme, the position of the second working medium inlet on the fourth pipeline is arranged at one end close to the outlet of the high-pressure cabin.

In the above scheme, a gas storage tank is arranged between the second high-pressure bin and the compressor, and a secondary compressor is arranged between the second high-pressure bin and the gas storage tank.

In the above scheme, the heat storage tank has still been seted up the secondary heating pipeline and has been linked to the pump respectively through high-pressure storehouse and second high-pressure storehouse and retrieve tubular heat collection field again, the front end of secondary heating pipeline sets up the distribution valve and is used for distributing the heating pipeline that secondary heating pipe and heat exchanger correspond.

In the above scheme, an auxiliary heat source pipeline is further arranged outside the tubular heat collection field, one end of the auxiliary heat source pipeline is communicated with the tubular heat collection field, the other end of the auxiliary heat source pipeline is communicated with the pump, and the auxiliary heat source adopts industrial low-temperature waste heat or a heat supply mode of a geothermal well.

In the above scheme, a low-temperature heat storage tank is further arranged on a pipeline between the heat exchanger and the tubular heat collection field, and the low-temperature heat storage tank is close to one end of the heat exchanger.

The invention also provides a control method of the photo-thermal low-temperature power generation system, which comprises a photo-thermal heat storage mode and a first organic working medium circulation mode and comprises the following steps:

(1) in the photo-thermal heat storage mode, the tubular heat collection field collects solar heat, and after water absorbs heat and is heated to a preset temperature to become hot water, the hot water enters the heat storage tank to be stored, so that the photo-thermal heat storage is completed. Stored hot water is shunted by a distribution valve and enters a tube bundle in the heat exchanger for heat exchange, a first organic working medium is heated by heat exchange to obtain temperature rise and vaporization, the temperature rise is 56-85 ℃, the pressure is 1.5-2.9 MPa, and the water after heat exchange is recycled to a tubular heat collection field for photo-thermal heat storage again;

(2) under the first organic working medium circulation mode, the distribution valve distributes a secondary heating pipeline to perform compensation heating on the first organic working medium in the high-pressure bin, and the first organic working medium in the high-pressure bin is conveyed to a fourth pipeline; under a second working medium circulation mode, the distribution valve distributes a secondary heating pipeline to perform compensation heating on a second working medium in the second high-pressure bin, the temperature of the temperature rise is 30-70 ℃, the pressure is 7-10 MPa, the second working medium in the gas storage tank enters the second high-pressure bin from the secondary compressor, enters the fourth pipeline from the fifth pipeline through the flow regulating valve to be mixed with the first organic working medium, the mixed organic working medium is formed and is conveyed to a power generation system, enters the steam turbine to perform expansion work, and outputs electric energy to the power transmission and transformation grid;

(3) the mixed organic working medium after expanding to do work and release energy is cooled by a condenser, the separated first organic working medium is recycled to a heat exchanger for circulation by a working medium pump after passing through a gas-liquid separator, and the second working medium is pressurized to supercritical pressure after passing through a compressor, a gas storage tank and a secondary compressor and then enters a second high-pressure cabin for circulation again.

In the scheme, the temperature of the first organic working medium in the step (1) is 70 ℃, and the pressure is 2.1 MPa; the temperature of the second working medium in the step (2) is 30 ℃, and the pressure is 7.1 MPa.

Compared with the prior art, the photo-thermal low-temperature power generation system and the control method thereof provided by the scheme of the invention have the beneficial effects that:

1. the system adopts mixed gas input, uses low-temperature organic working medium R134a as a temperature-contrast substrate, and adds special working medium CO₂Or N₂The ultra-high pressure can be generated under the condition of low temperature to push the machine to do work; the adoption of mixed working medium can effectively solve CO₂Or N₂The specific heat capacity of the working medium is low in the conveying process, the critical temperature is difficult to maintain, and the work is unstable.

2. The system belongs to a low-temperature medium-voltage power generation system, the constant pressure of the original machine working quality parameter design is 2.1MPa, the temperature is set to be 70 ℃, the mixed system is changed from the original low-temperature medium-voltage to a low-temperature high-voltage or low-temperature ultrahigh-voltage system, namely, the pressure is improved under the condition of not changing the total heat input, the power generation power of a single unit is obviously increased, the original 3-5MW is increased to 25MW, and the output power is increased to more than 5 times of the original power generation power.

3. The system is provided with a plurality of heat storage devices, the ambient temperature of the organic working medium can be adjusted as required, the power generation system is stable, the heat consumption is less, and the cost of the heating system is reduced.

Drawings

FIG. 1 is a schematic diagram of a photothermal low temperature power generation system according to the present invention;

fig. 2 is a schematic diagram of a control method of a photo-thermal low-temperature power generation system according to the present invention.

In the figure: 1. the system comprises a tubular heat collection field, 2, a first pipeline, 3, a heat storage tank, 4, a second pipeline, 5, a switching valve, 6, a heat exchanger, 7, a secondary heating pipeline, 8, a high-pressure chamber, 9, a second high-pressure chamber, 10, a high-pressure chamber outlet, 11, a second working medium inlet, 12, a flow regulating valve, 13, a fourth pipeline, 14, a fifth pipeline, 15, a compressor, 16, a steam turbine, 17, a generator, 18, a power transmission network, 19, a booster station, 20, an eighth pipeline, 21, a condenser, 22, a sixth pipeline, 23, a second working medium outlet, 24, a mixed organic working medium inlet, 25, a gas-liquid separator, 26, a first organic working medium outlet, 27, a gas storage tank, 28, a seventh pipeline, 29, a working medium pump, 30, a secondary compressor, 31, a low-temperature heat storage tank, 32, a water pump, 33, an auxiliary heat source and a one-way.

Detailed Description

The invention is further described with reference to the following detailed description of embodiments in conjunction with the accompanying drawings:

referring to fig. 1, the photo-thermal low-temperature power generation system of the present invention includes a photo-thermal circulation system and a first organic working medium circulation system; the photothermal circulating system comprises a circulating loop formed by connecting a tubular heat collecting field 1, a heat exchanger 6 with a first organic working medium arranged inside and a tube bundle inside, wherein the tubular heat collecting field 1 is communicated with a heat storage tank 3 through a first pipeline 2, the heat storage tank 3 is communicated with the heat exchanger 6 through a second pipeline 4, and the heat exchanger 6 heats and vaporizes the first organic working medium and inputs the first organic working medium into the first organic working medium circulating system; the first organic working medium circulating system comprises a working medium circulating loop formed by sequentially connecting a high-pressure bin 8, a steam turbine 16, a condenser 21 and a working medium pump 29. The first organic working fluid is R134 a.

The first organic working medium circulation system is also provided with a second working medium circulation system, the second working medium circulation system comprises a second high-pressure bin 9 and a compressor 15, the compressor 15 conveys a second working medium to the second high-pressure bin 9 through a seventh pipeline 28, and a gas storage tank 27 is arranged between the second high-pressure bin 9 and the compressor 15. A secondary compressor 30 is arranged between the second high-pressure chamber 9 and the air storage tank 27. A fourth pipeline 13 between the high-pressure bin 8 and the steam turbine 16 is provided with a second working medium inlet 11 communicated with the second high-pressure bin 9, and the position of the second working medium inlet 11 on the fourth pipeline 13 is arranged at one end close to the high-pressure bin outlet 10. A flow regulating valve 12 is arranged outside the second working medium inlet 11, the second high-pressure bin 9 is connected with the flow regulating valve 12 through a fifth pipeline 14, the high-pressure bin 8 comprises a high-pressure bin outlet 10, and a check valve 34 is arranged on a fourth pipeline 13 between the high-pressure bin outlet 10 and the second working medium inlet 11. The second working medium is CO₂Or N₂。

A gas-liquid separator 25 is arranged on the sixth pipeline 22 between the condenser 21 and the working medium pump 29, the gas-liquid separator 25 comprises a mixed gas working medium inlet 24, a first organic working medium outlet 26 and a second working medium outlet 23, the mixed gas working medium inlet 24 is connected with the sixth pipeline 22, the first organic working medium outlet 26 is connected with the working medium pump 29, the second working medium outlet 23 is connected with the compressor 15 through an eighth pipeline 20, and the second working medium is compressed to a gas storage tank 27 and is connected into the working mediumA circulation loop, the first organic working medium is R134a, and the second working medium is CO₂Or N₂。

The heat storage tank 3 is further provided with a secondary heating pipeline 7 which is respectively communicated to the high-pressure bin 8 and the second high-pressure bin 9 and then connected to the tubular heat collection field 1 by a pump 32, and the front end of the secondary heating pipeline 7 is provided with a distribution valve 5 for distributing heating pipelines corresponding to the secondary heating pipe 7 and the heat exchanger 6. An auxiliary heat source 33 is further arranged outside the tubular heat collection field 1, one end of the auxiliary heat source 33 is communicated with the tubular heat collection field 1, the other end of the auxiliary heat source 33 is communicated with the pump 32, and the auxiliary heat source 33 adopts a heat supply mode of industrial low-temperature waste heat or a geothermal well. A low-temperature heat storage tank 32 is further arranged on a pipeline between the heat exchanger 6 and the tubular heat collection field 1, and one end of the low-temperature heat storage tank 32 close to the heat exchanger 6 is provided.

Referring to fig. 1 and 2, the control process of the present invention is:

(1) in the photo-thermal heat storage mode, the tubular heat collection field 1 collects solar heat, and after water absorbs heat and is heated to a preset temperature to become hot water, the hot water enters the heat storage tank 3 to complete photo-thermal heat storage. Hot water is shunted by a distribution valve 5 and enters a tube bundle in a heat exchanger 6 for heat exchange, so that a first organic working medium R134a is heated to 70 ℃, the temperature is raised, the pressure after vaporization is 2.1MPa, the heated water is input into a high-pressure bin 8, the heat-exchanged water is stored in a low-temperature heat storage tank 31 and is recycled to a tubular heat collection field 1 by a pump 32 for photo-thermal heat storage again;

(2) under the first organic working medium circulation mode, because heat loss Q1 exists in the heat transfer process, when the temperature of the first organic working medium in the high-pressure cabin 8 is lower than 70 ℃, it indicates that the pressure of the fourth pipeline 13 is less than 2.1MPa, then the distribution valve 5 distributes the secondary heating pipeline 7 to perform compensation heating on the first organic working medium R134a in the high-pressure cabin 8 to obtain Q1, then the first organic working medium R134a sequentially enters the fourth pipeline 13 through the one-way valve 34 to be conveyed, and through secondary heating, the first organic working medium R134a in the high-pressure cabin 8 is finally kept in a critical state with the temperature of 70 ℃ and the pressure of 2.1MPa, so as to ensure the constant temperature of the temperature-supporting matrix and ensure the ideal performance of the thermal expansion pressure.

In the second working medium circulation mode, because heat loss Q2 exists in the heat transfer process, when the temperature of the second working medium in the second high-pressure bin 9 is less than 30 ℃, the pressure of the fifth pipeline 14 is also shownWhen the pressure is less than 7.1MPa, the distribution valve 5 distributes a secondary heating pipeline 7 to the second working medium CO2 in the second high-pressure bin 9 for compensation heating Q2, and then the second working medium CO2 is input into the fifth pipeline 14 and is secondarily heated in the second high-pressure bin 9₂The temperature is kept at 30 ℃ and the pressure is kept at 7.1MPa, and then the mixture enters a fourth pipeline 13 from a fifth pipeline 14 through a flow regulating valve 12 to be mixed with a high-temperature first organic working medium R134a, and the first organic working medium R134a is used as a temperature-based substrate (thermal base) to ensure that a second working medium CO is used as a thermal base₂Maintaining the supercritical temperature state to form a mixed organic working medium, conveying the mixed organic working medium to a power generation system, entering a steam turbine 16 for expansion work, and outputting electric energy to a power transmission network 18 by a generator 17 through a booster station 19;

(3) the mixed organic working medium after the mixed organic working medium expands to do work and release energy is conveyed to a condenser 21 by a steam turbine 16 for cooling, after the mixed organic working medium passes through a gas-liquid separator 25, a separated first organic working medium R134a is recycled to a heat exchanger 6 by a working medium pump 29 for circulation, and a second working medium CO₂After passing through the compressor 15, the air storage tank 27 and the secondary compressor 30, the pressure is increased to the critical pressure, and the pressure enters the second high-pressure cabin 9 again for circulation.

The system adopts mixed gas input, utilizes a low-temperature organic working medium R134a as a temperature-contrast substrate, and then adds special working medium CO₂Or N₂Can generate ultrahigh pressure to push machinery to do work under the condition of low temperature, and the mixed working medium can effectively solve the problem of CO₂Or N₂The problem that the specific heat capacity of the working medium is low in the conveying process, the critical temperature is difficult to keep, and the working is unstable can also enable the mixed system to be changed from the original low-temperature medium-pressure system into a low-temperature high-pressure or low-temperature ultrahigh-pressure system, namely, the pressure is improved under the condition that the total heat input is not changed, the generating power of a single unit is obviously increased and is improved to 25MW from the original 3-5MW, and the output power is improved to more than 5 times of the original output power. The system is provided with a feedback control system, so that the environmental temperature of the organic working medium can be adjusted according to the requirement for automatic control, the stability of the power generation system is ensured, the heat consumption is less, and the cost of the heating system is favorably reduced.

Although the present invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present invention.