A water and heat co-production and co-delivery system combined with a thermal power plant and its working method

Abstract

The present invention discloses a water and heat co-production and co-delivery system combined with a thermal power plant and a working method thereof. The present invention utilizes the waste heat of flue gas to heat the desalinated seawater product water, and realizes the high-temperature product water as a water and heat co-carrier medium for transportation. On the one hand, it effectively utilizes the waste heat of flue gas for external heat supply, reduces the flue gas emission loss, improves the operation efficiency of the unit, and effectively reduces the heat supply energy consumption. On the other hand, it realizes the external water and heat co-delivery of the power plant, enriching the diversity of the external supply products of the power plant. Compared with the water and heat separate delivery system, it simplifies the pipeline layout of the system and reduces the pipeline construction and maintenance costs.

Description

Technical Field

[0001] The present invention belongs to the technical field of heat supply and seawater utilization, and particularly relates to a water and heat co-production and co-delivery system combined with a thermal power plant and a working method thereof. Background Art

[0002] Centralized heat supply is an organizational mode of regional energy production that constructs centralized heat sources in industrial production areas and areas where urban residents gather, and provides heat for production and living for enterprises and residents in this area and its surroundings. Since centralized heat supply can save fuel, is easy to be large-scale and mechanized, and can also centrally solve problems such as smoke exhaust pollution and ash slag fuel stacking, it has obvious economic, environmental and social benefits, and has now become one of the important infrastructure for modern urban construction.

[0003] However, at present, the coverage rate of centralized heat supply in China is still at a relatively low level. Centralized heat supply systems are only built in the main towns of northern provinces, while there are basically no centralized heating facilities in southern towns and vast rural areas of our country, and only independent heating methods such as natural gas furnaces, air conditioners, electric furnaces and honeycomb coal can be relied on for heating. In developed countries such as Finland and Denmark, the urban centralized heat supply coverage rate reaches 90%, and the national average level is also above 60%. The future development of the real estate industry, the improvement of the urbanization rate, the demolition of regional small boilers and the construction and transformation of pipe networks in old urban areas have all created huge and continuous demands for the centralized heat supply market, and the centralized heat supply industry in China has very broad development prospects.

[0004] On the other hand, with the rapid development of clean energy power generation such as wind and light, thermal power units are gradually transforming from the main position of power supply in the power system to the position of ensuring power supply and providing a backup. To improve the profitability and survival competitiveness of power plants, thermal power units need to transform from single electric energy supply to comprehensive energy supply bases for electricity, heat, steam, cold, water, etc., and enrich the diversity of external supply products. For coastal power plants, combining seawater desalination with the power generation thermal cycle and using the exhaust steam of the power plant to provide steam required for seawater desalination can greatly reduce the cost of seawater desalination and improve the profitability of the power plant. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above deficiencies, and provide a water and heat co-production and co-delivery system combined with a thermal power plant and a working method thereof. By combining a seawater desalination device with the power generation cycle of a thermal power plant, the power plant can externally co-deliver water and heat, enrich the diversity of external supply products of the power plant, and at the same time reduce the system construction and maintenance costs.

[0006] To achieve the above object, a water and heat co-production and co-supply system combined with a thermal power plant includes a boiler. The boiler is connected to a steam turbine through a steam pipeline, the steam turbine is connected to a generator, the exhaust pipeline of the steam turbine is connected to a condenser and a multi-effect distillation seawater desalination device. The condenser is cooled by seawater, and the coolant outlet of the condenser is connected to the multi-effect distillation seawater desalination device. The multi-effect distillation seawater desalination device is used for multi-stage distillation of seawater to generate concentrated brine and product water;

[0007] The product water outlet of the multi-effect distillation seawater desalination device is connected to a secondary flue gas heat exchanger. The product water after being heated at the outlet of the secondary flue gas heat exchanger is connected to a primary flue gas heat exchanger through a pipeline. The high-temperature product water at the outlet of the primary flue gas heat exchanger is sent to the user side through a conveying pipeline;

[0008] The multi-effect distillation seawater desalination device is connected to the user side through a product water conveying pipeline.

[0009] A first valve is provided on the connecting pipeline between the steam turbine and the multi-effect distillation seawater desalination device.

[0010] A second valve is provided on the connecting pipeline between the coolant outlet of the condenser and the multi-effect distillation seawater desalination device.

[0011] A third valve is provided on the connecting pipeline between the multi-effect distillation seawater desalination device and the secondary flue gas heat exchanger.

[0012] A fourth valve is provided on the connecting pipeline between the multi-effect distillation seawater desalination device and the user side.

[0013] The condenser is connected to the unit condensate water system.

[0014] The user side includes a heat exchange device. The heat exchange device is connected to the conveying pipeline. The heat exchange device is used for exchanging heat between the high-temperature product water and the return water of the urban heat network, transferring heat to the return water of the urban heat network. The high-temperature product water becomes normal-temperature product water, and the normal-temperature product water is supplied to a water plant or other fresh water users.

[0015] A fifth valve is provided on the connecting pipeline between the conveying pipeline and the heat exchange device, and a sixth valve is provided on the connecting pipeline between the conveying pipeline and the water plant.

[0016] The flue gas outlet of the boiler is connected to an air preheater, the air preheater is connected to a primary flue gas heat exchanger, the primary flue gas heat exchanger is connected to a dust collector, the dust collector is connected to an induced draft fan, the induced draft fan is connected to a booster fan, the booster fan is connected to a secondary flue gas heat exchanger, and the secondary flue gas heat exchanger is connected to a chimney.

[0017] A working method of a water and heat co-production and co-supply system combined with a thermal power plant includes the following steps:

[0018] When starting the seawater desalination device, part of the heated seawater discharged from the condenser enters the multi-effect distillation seawater desalination device as raw seawater, and part of the exhaust steam of the steam turbine enters the multi-effect distillation seawater desalination device as the driving heat source. After the raw seawater and the exhaust steam complete multi-stage distillation in the multi-effect distillation seawater desalination device, the exhaust steam condenses and releases heat and returns to the condensate system of the unit, and the seawater is separated into brine and product water;

[0019] When the unit supplies heat to the outside at the same time, the product water discharged from the multi-effect distillation seawater desalination device enters the secondary flue gas heat exchanger to exchange heat with the flue gas. After the product water is heated up, it enters the primary flue gas heat exchanger for secondary heating and temperature rise. The high-temperature product water discharged from the primary flue gas heat exchanger enters the conveying pipeline and is conveyed to the user side;

[0020] When the unit does not supply heat to the outside, the product water discharged from the multi-effect distillation seawater desalination device is directly sent into the conveying pipeline and conveyed to the user side.

[0021] When starting the seawater desalination device, open the first valve and the second valve;

[0022] When the unit supplies heat to the outside, open the third valve and the fifth valve, and close the fourth valve and the sixth valve;

[0023] When the unit does not supply heat to the outside, close the third valve and the fifth valve, and open the fourth valve and the sixth valve.

[0024] Compared with the prior art, the present invention uses the waste heat of the flue gas to heat the product water of seawater desalination, and realizes the high-temperature product water as a water and heat co-carrier medium for transportation. On the one hand, it effectively utilizes the waste heat of the flue gas for external heat supply, reduces the flue gas loss, improves the operation efficiency of the unit, and effectively reduces the heat supply energy consumption. On the other hand, it realizes the simultaneous supply of water and heat from the power plant to the outside, enriching the diversity of the external supply products of the power plant. Compared with the water and heat separate supply system, it simplifies the pipeline layout of the system and reduces the pipeline construction and maintenance costs. Brief Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the system of the present invention;

[0026] Among them, 1. Boiler, 2. Steam turbine, 3. Generator, 4. Condenser, 5. Air preheater, 6. Primary flue gas heat exchanger, 7. Dust collector, 8. Induced draft fan, 9. Booster fan, 10. Secondary flue gas heat exchanger, 11. Chimney, 12. Multi-effect distillation seawater desalination device, 13. Conveying pipeline, 14. Heat exchange device, 15. First valve, 16. Second valve, 17. Third valve, 18. Fourth valve, 19. Fifth valve, 20. Sixth valve. Detailed Embodiments

[0027] The present invention will be further described below with reference to the drawings.

[0028] See Figure 1 Figure 1 , a water and heat co-production and co-delivery system combined with a thermal power plant, including a boiler 1. The boiler 1 is connected to a steam turbine 2 through a steam pipeline. The steam turbine 2 is connected to a generator 3. The exhaust steam pipeline of the steam turbine 2 is connected to a condenser 4 and a multi-effect distillation seawater desalination device 12. A first valve 15 is provided on the connecting pipeline between the steam turbine 2 and the multi-effect distillation seawater desalination device 12. The condenser 4 is cooled by seawater and is connected to the unit condensate water system. The coolant outlet of the condenser 4 is connected to the multi-effect distillation seawater desalination device 12. A second valve 16 is provided on the connecting pipeline between the coolant outlet of the condenser 4 and the multi-effect distillation seawater desalination device 12. The multi-effect distillation seawater desalination device 12 is used for multi-stage distillation of seawater to generate concentrated brine and product water. The flue gas outlet of the boiler 1 is connected to an air preheater 5. The air preheater 5 is connected to a primary flue gas heat exchanger 6. The primary flue gas heat exchanger 6 is connected to a dust collector 7. The dust collector 7 is connected to an induced draft fan 8. The induced draft fan 8 is connected to a booster fan 9. The booster fan 9 is connected to a secondary flue gas heat exchanger 10. The secondary flue gas heat exchanger 10 is connected to a chimney 11.

[0029] The product water outlet of the multi-effect distillation seawater desalination device 12 is connected to the secondary flue gas heat exchanger 10. A third valve 17 is provided on the connecting pipeline between the multi-effect distillation seawater desalination device 12 and the secondary flue gas heat exchanger 10. The heated product water outlet of the secondary flue gas heat exchanger 10 is connected to the primary flue gas heat exchanger 6 through a pipeline. The high-temperature product water outlet of the primary flue gas heat exchanger 6 is sent to the user side through a conveying pipeline 13.

[0030] The multi-effect distillation seawater desalination device 12 is connected to the user side through a product water conveying pipeline. A fourth valve 18 is provided on the product water conveying pipeline.

[0031] The user side includes a heat exchange device 14. The heat exchange device 14 is connected to the conveying pipeline 13. A fifth valve 19 is provided on the connecting pipeline between the conveying pipeline 13 and the heat exchange device 14. A sixth valve 20 is provided on the connecting pipeline between the conveying pipeline 13 and the water plant. The heat exchange device 14 is used for heat exchange between the high-temperature product water and the return water of the urban heat network, transferring heat to the return water of the urban heat network. The high-temperature product water becomes normal-temperature product water, and the normal-temperature product water is supplied to the water plant or other fresh water users.

[0032] The working method of the present invention is as follows:

[0033] The new steam at the outlet of the boiler 1 enters the steam turbine 2 to do work and drive the generator 3 to generate electricity. The exhaust steam of the steam turbine 2 enters the condenser 4 to be condensed and then returns to the unit condensate water system. The condenser 4 is cooled by seawater.

[0034] The flue gas generated by the boiler 1 flows through the air preheater 5, the primary flue gas heat exchanger 6, the dust collector 7, the induced draft fan 8, the booster fan 9, and the secondary flue gas heat exchanger 10 in sequence, and then is discharged through the chimney 11.

[0035] When starting the seawater desalination device, open the first valve 15 and the second valve 16. The heated seawater at the outlet of the condenser 4 enters the multi-effect distillation seawater desalination device 12 as raw seawater, and part of the exhaust steam of the steam turbine 2 enters the multi-effect distillation seawater desalination device 12 as the driving heat source. After the raw seawater and the exhaust steam complete multi-stage distillation in the multi-effect distillation seawater desalination device 12, the exhaust steam condenses and releases heat and returns to the unit condensate system, and the seawater is separated into brine and product water.

[0036] When the unit supplies heat to the outside at the same time, open the third valve 17 and the fifth valve 19, and close the fourth valve 18 and the sixth valve 20. The product water at the outlet of the multi-effect distillation seawater desalination device 12 enters the secondary flue gas heat exchanger 10 to exchange heat with the flue gas. After the product water is heated up, it enters the primary flue gas heat exchanger 6 for secondary heating and temperature rise. Then the high-temperature product water enters the conveying pipeline 13 and is conveyed to the user side. On the user side, the high-temperature product water exchanges heat with the return water of the urban heat network in the heat exchange device 14, transfers the heat to the heat network water, and becomes normal-temperature product water, and then is supplied to the water plant or other fresh water users.

[0037] The conveying pipeline 13 is provided with a heat insulation layer to reduce the heat loss of the high-temperature product water during the conveying process.

[0038] When the unit does not supply heat to the outside, close the third valve 17 and the fifth valve 19, open the fourth valve 18 and the sixth valve 20. The product water at the outlet of the multi-effect distillation seawater desalination device 12 is directly sent into the conveying pipeline 13 and conveyed to the user side. On the user side, the product water is conveyed to the water plant or other fresh water users through the sixth valve 20. The unit condensate passes through the secondary flue gas heat exchanger 10 and the primary flue gas heat exchanger 6 in turn to exchange heat with the flue gas to ensure the operation safety of the flue gas heat exchanger.

Claims

1. A water and heat co-production and co-delivery system combined with a thermal power plant, characterized in that It includes a boiler (1), the boiler (1) is connected to a steam turbine (2) through a steam pipeline, the steam turbine (2) is connected to a generator (3), the exhaust steam pipeline of the steam turbine (2) is connected to a condenser (4) and a multi-effect distillation seawater desalination device (12), the condenser (4) is cooled by seawater, the coolant outlet of the condenser (4) is connected to the multi-effect distillation seawater desalination device (12), and the multi-effect distillation seawater desalination device (12) is used for multi-stage distillation of seawater to generate concentrated brine and product water; The product water outlet of the multi-effect distillation seawater desalination device (12) is connected to a secondary flue gas heat exchanger (10), the heated product water at the outlet of the secondary flue gas heat exchanger (10) is connected to a primary flue gas heat exchanger (6) through a pipeline, and the high-temperature product water at the outlet of the primary flue gas heat exchanger (6) is sent to the user side through a conveying pipeline (13); The multi-effect distillation seawater desalination device (12) is connected to the user side through a product water conveying pipeline; The user side includes a heat exchange device (14), the heat exchange device (14) is connected to the conveying pipeline (13), and the heat exchange device (14) is used for exchanging heat between the high-temperature product water and the return water of the urban heat network, transferring heat to the return water of the urban heat network, the high-temperature product water becomes normal-temperature product water, and the normal-temperature product water is supplied to a water plant or other fresh water users; The flue gas outlet of the boiler (1) is connected to an air preheater (5), the air preheater (5) is connected to a primary flue gas heat exchanger (6), the primary flue gas heat exchanger (6) is connected to a dust collector (7), the dust collector (7) is connected to an induced draft fan (8), the induced draft fan (8) is connected to a booster fan (9), the booster fan (9) is connected to a secondary flue gas heat exchanger (10), and the secondary flue gas heat exchanger (10) is connected to a chimney (11).

2. The water and heat co-production and co-delivery system combined with a thermal power plant according to claim 1, wherein A first valve (15) is provided on the connecting pipeline between the steam turbine (2) and the multi-effect distillation seawater desalination device (12); A second valve (16) is provided on the connecting pipeline between the coolant outlet of the condenser (4) and the multi-effect distillation seawater desalination device (12).

3. A water and heat co-production and co-delivery system combined with a thermal power plant according to claim 1, characterized in that, A third valve (17) is provided on the connecting pipeline between the multi-effect distillation seawater desalination device (12) and the secondary flue gas heat exchanger (10).

4. A water and heat co-production and co-delivery system combined with a thermal power plant according to claim 1, characterized in that, A fourth valve (18) is provided on the connecting pipeline between the multi-effect distillation seawater desalination device (12) and the user side.

5. A water and heat co-production and co-supply system combined with a thermal power plant according to claim 1, characterized in that, The condenser (4) is connected to the unit condensate water system.

6. A water and heat co-production and co-delivery system combined with a thermal power plant according to claim 1, characterized in that A fifth valve (19) is provided on the connecting pipeline between the conveying pipeline (13) and the heat exchange device (14), and a sixth valve (20) is provided on the connecting pipeline between the conveying pipeline (13) and the water plant.

7. The working method of a water and heat co-production and co-delivery system combined with a thermal power plant according to claim 1, characterized in that, It includes the following steps: When starting the seawater desalination device, a part of the heated seawater discharged from the condenser (4) enters the multi-effect distillation seawater desalination device (12) as raw seawater, a part of the exhaust steam of the steam turbine (2) enters the multi-effect distillation seawater desalination device (12) as a driving heat source, after the raw seawater and the exhaust steam complete multi-stage distillation in the multi-effect distillation seawater desalination device (12), the exhaust steam condenses and releases heat and returns to the unit condensate water system, and the seawater is separated into concentrated brine and product water; When the unit supplies heat externally at the same time, the product water discharged from the multi-effect distillation seawater desalination device (12) enters the secondary flue gas heat exchanger (10) to exchange heat with the flue gas. After the product water is heated up, it enters the primary flue gas heat exchanger (6) for secondary heating and temperature rise. The high-temperature product water discharged from the primary flue gas heat exchanger (6) enters the conveying pipeline (13) and is conveyed to the user side; When the unit does not supply heat externally, the product water discharged from the multi-effect distillation seawater desalination device (12) is directly fed into the conveying pipeline (13) and conveyed to the user side.

8. The working method of a water and heat co-production and co-delivery system combined with a thermal power plant according to claim 7, characterized in that, When starting the seawater desalination device, open the first valve (15) and the second valve (16); When the unit supplies heat externally, open the third valve (17) and the fifth valve (19), and close the fourth valve (18) and the sixth valve (20); When the unit does not supply heat externally, close the third valve (17) and the fifth valve (19), and open the fourth valve (18) and the sixth valve (20).

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