Tower-type solar energy and lignite coal combined power generation system

Abstract

The present invention relates to the technical field of power generation, and disclosed is a tower-type solar energy and lignite coal combined power generation system, comprising a boiler subsystem, a steam turbine and feed-water preheating subsystem, and a flue gas treatment subsystem. High-temperature flue gas generated by combustion in a furnace first flows into the flue gas treatment subsystem for desulfurization and decarbonization, then sequentially flows through a lignite pre-dryer and a feed-water / flue gas heat exchanger, and is finally discharged; lignite is heated and dried by the flue gas in the lignite pre-dryer and then is fed to the furnace for combustion; superheated steam from the boiler subsystem enters a steam turbine to do work, and exhaust steam is collected and cooled in a condenser, then flows into a feed-water heating assembly to be heated and then is fed into the boiler subsystem to be heated into the superheated steam; and the feed-water / flue gas heat exchanger is connected to the feed-water heating assembly in parallel to heat feed water. The system of the present invention has the advantages of lowering fuel consumption, improving power generation efficiency, and the like, and can solve the coal drying and desulfurization and decarburization integration problem of a lignite power plant.

Description

A tower-type solar energy and lignite-fired combined power generation system Technical Field

[0001] The present invention belongs to the field of power generation technology, and relates to a multi-energy comprehensive utilization power generation system of new energy and coal, and in particular to a tower-type solar energy and lignite-fired combined power generation system integrating calcium cycle desulfurization and decarbonization, lignite drying and feed water preheating. Background Art

[0002] Currently, decarbonization in coal-fired power plants can be categorized into pre-combustion decarbonization, post-combustion decarbonization, and oxygen-enriched combustion decarbonization. Post-combustion decarbonization is more suitable for retrofitting existing power plants. Amine-based or calcium-based absorbents are commonly used for post-combustion decarbonization. Calcium-based absorbents are relatively inexpensive and readily available due to the widespread availability of raw materials in nature. They also provide desulfurization. A common calcium-based absorbent is CaO. In the carbonization furnace, CaO reacts with CO2-containing flue gas to produce a large amount of CaCO3. The generated CaCO3 absorbs heat in the calciner to form a mixture of CaO and CO2. The separated CaO then re-enters the carbonization furnace for the next carbon cycle, while the separated CO2 is compressed and stored. The decomposition of CaCO3 in the calciner consumes a significant amount of heat. Currently, additional coal or natural gas is often burned to provide this heat, which inevitably reduces power plant efficiency and produces additional greenhouse gases.

[0003] To balance power plant efficiency and decarbonization, it is crucial to seek external resources, such as renewable ones, to improve energy conversion efficiency. Solar thermal energy, with its vast reserves and widespread distribution, is an ideal "external" resource for coal-fired power plants. Coupling solar thermal energy with coal-fired power plants is feasible. First, existing solar thermal collection technology can meet the temperature requirements for CaCO3 decomposition. Second, the intermittent and unstable nature of solar radiation can be overcome with more efficient heat-to-power conversion equipment in coal-fired power plants. Third, my country's coal-rich regions overlap significantly with those rich in solar resources, offering geographical advantages.

[0004] Existing technologies have proposed the need to recover waste heat from tower-type solar-assisted desulfurization and decarbonization processes and integrate it into the system's temperature-matched heat absorption process, which will help improve the system's energy conversion efficiency. However, these systems do not consider the impact of coal type differences on the technical approach. Currently, my country's proven lignite reserves account for approximately 13% of the country's total coal reserves. Its abundant reserves and low price have gradually become the main fuel for thermal power generation in my country. However, lignite has a low degree of coal quality, a moisture content of up to 20%-50%, and a low calorific value, which in turn leads to high investment and low efficiency in lignite power generation systems.

[0005] Summary of the Invention

[0006] The present invention provides a tower-type solar energy and lignite coal-fired combined power generation system integrating calcium circulation desulfurization and decarbonization, lignite drying and feed water preheating, so as to overcome the defects of the prior art.

[0007] To achieve the above-mentioned purpose, the present invention provides a tower-type solar energy and lignite coal-fired combined power generation system, which has the following characteristics: it includes a boiler subsystem, a steam turbine, a feed water preheating subsystem and a flue gas treatment subsystem; the boiler subsystem includes a furnace, a lignite predryer and a feed water / flue gas heat exchanger; the furnace, the flue gas treatment subsystem, the lignite predryer and the feed water / flue gas heat exchanger are connected in sequence, and the lignite predryer is also connected to the furnace; the high-temperature flue gas generated by combustion in the furnace first flows into the flue gas treatment subsystem for desulfurization and decarbonization, and then flows through the lignite predryer and the feed water / flue gas heat exchanger in sequence. The lignite is heated and dried by flue gas in the lignite predryer and then sent to the furnace for combustion; the steam turbine and feed water preheating subsystem include a steam turbine, a condenser and a feed water heating component; the boiler subsystem, the steam turbine, the condenser and the feed water heating component are connected in sequence; the superheated steam from the boiler subsystem enters the steam turbine to perform work, and the exhaust steam is collected and cooled in the condenser, pressurized by the feed water pump, and then flows into the feed water heating component to be heated, and then sent to the boiler subsystem to be heated into superheated steam; the feed water / flue gas heat exchanger is connected in parallel with the feed water heating component to heat the feed water.

[0008] Furthermore, the present invention provides a tower-type solar energy and lignite coal-fired combined power generation system, which may also have the following characteristics: wherein, the boiler subsystem also includes a steam drum, an overheating component and an economizer; the furnace is connected to the overheating component, and the overheating component is further connected to the flue gas treatment subsystem, and the flue gas treatment subsystem is connected to the lignite pre-dryer through the economizer; the high-temperature flue gas generated by the furnace combustion first flows through the overheating component to be cooled, and then enters the flue gas treatment subsystem for desulfurization and decarbonization, and then flows through the economizer to be cooled and enters the lignite pre-dryer; the steam turbine and feed water preheating subsystem, economizer, steam drum and superheating component are connected in sequence, and the steam drum is also connected to the furnace; the feed water from the steam turbine and feed water preheating subsystem is heated by the economizer and then enters the steam drum, the liquid in the steam drum enters the water-cooled wall for heating and then returns to the steam drum, the gas in the steam drum first enters the overheating component for heating, and the generated superheated steam enters the steam turbine and feed water preheating subsystem to perform work.

[0009] Furthermore, the present invention provides a tower-type solar energy and lignite-fired combined power generation system, which may also have the following characteristics: wherein, the superheating component includes a platen superheater, a low-temperature reheater, a high-temperature superheater, a high-temperature reheater and a low-temperature superheater; the furnace is connected to the platen superheater, the low-temperature reheater, the high-temperature superheater, the high-temperature reheater and the low-temperature superheater in sequence, and the low-temperature superheater is further connected to the flue gas treatment subsystem; the high-temperature flue gas generated by the combustion in the furnace flows through the platen superheater, the low-temperature reheater, the high-temperature superheater, the high-temperature reheater and the low-temperature superheater in sequence to be cooled, and then enters The flue gas treatment subsystem performs desulfurization and decarbonization; the steam drum is connected to the low-temperature superheater, the platen superheater and the high-temperature superheater in sequence, and the high-temperature superheater is then connected to the high-pressure cylinder of the steam turbine; the gas in the steam drum is first heated by the low-temperature superheater, the platen superheater and the high-temperature superheater in sequence, and then enters the high-pressure cylinder of the steam turbine to perform work; the high-pressure cylinder, low-temperature reheater, high-temperature reheater of the steam turbine and the intermediate-pressure cylinder and low-pressure cylinder of the steam turbine are connected in sequence; the exhaust steam of the high-pressure cylinder of the steam turbine flows into the low-temperature reheater and the high-temperature reheater in sequence to be heated, and then enters the intermediate-pressure cylinder and low-pressure cylinder of the steam turbine to perform work.

[0010] Furthermore, the present invention provides a tower-type solar energy and lignite-fired combined power generation system, which may also have the following characteristics: wherein, the steam turbine and feed water preheating subsystem also include a steam box; the high-temperature superheater is connected to the high-pressure cylinder of the steam turbine through the steam box; the superheated steam from the high-temperature superheater first enters the steam box, and then enters the high-pressure cylinder of the steam turbine to perform work; the steam box is also connected to the feed water heating assembly; the superheated steam enters the feed water heating assembly to heat the feed water.

[0011] Furthermore, the present invention provides a tower-type solar energy and lignite-fired combined power generation system, which may also have the following characteristics: wherein, in the steam turbine and feedwater preheating subsystem, the feedwater heating component heats the feedwater by extracting steam from the steam turbine.

[0012] Furthermore, the present invention provides a tower-type solar energy and lignite-fired combined power generation system, which may also have the following characteristics: wherein, the feedwater heating component includes eight feedwater heaters, and the high-pressure cylinder, medium-pressure cylinder and low-pressure cylinder of the steam turbine are respectively provided with eight-stage extraction steam, and the eight-stage extraction steam respectively enters the eight-stage feedwater heater for heating the feedwater; the sixth to eighth-stage feedwater heaters are connected in parallel with the feedwater / flue gas heat exchanger of the boiler subsystem.

[0013] Furthermore, the present invention provides a tower-type solar energy and lignite coal-fired combined power generation system, which may also have the following characteristics: wherein, the flue gas treatment subsystem includes a carbonization furnace, a carbonization furnace gas-solid separator, a purifier, a calciner, a calciner gas-solid separator, a solar heat collecting device and a first air preheater; the boiler subsystem, the carbonization furnace and the carbonization furnace gas-solid separator are connected in sequence; the flue gas from the boiler subsystem enters the carbonization furnace, reacts with CaO to generate CaCO3 and CaSO4, and then enters the carbonization furnace gas-solid separator to be separated into gas and solid, and the gas flows back to the boiler subsystem; the calciner is connected to the lignite predryer, and the carbonization furnace gas-solid separator, purifier, calciner The incinerator and the calciner gas-solid separator are connected in sequence, and the calciner gas-solid separator is connected to the carbonization furnace, the solar thermal collector and the first air preheater respectively; the solid separated by the carbonization furnace gas-solid separator enters the purifier for purification, and the obtained CaCO3 is mixed with the newly added CaCO3 and enters the calciner. The lignite dried by the lignite predryer enters the calciner for combustion to generate heat, and the CaCO3 is heated and decomposed into CaO and CO2. After gas-solid separation by the calciner gas-solid separator, the solid enters the carbonization furnace, and part of the gas is heated by the solar thermal collector and then returns to the calciner to provide energy, and part of the gas enters the first air preheater to preheat the air entering the furnace.

[0014] Furthermore, the present invention provides a tower-type solar energy and lignite-fired combined power generation system, which may also have the following characteristics: wherein, the flue gas treatment subsystem also includes a dust collector, a first heat exchanger, a second heat exchanger and a third heat exchanger; the dust collector and the first heat exchanger are sequentially connected between the boiler subsystem and the carbonization furnace, and the first heat exchanger is also connected to the gas-solid separator of the carbonization furnace; the flue gas from the boiler subsystem first flows through the dust collector for dust removal, and then passes through the first heat exchanger for preheating, and then enters the carbonization furnace; the gas separated by the gas-solid separator of the carbonization furnace The flue gas first enters the first heat exchanger to be preheated and then flows back to the boiler subsystem; the third heat exchanger is connected to the purifier, the second heat exchanger is connected between the purifier and the calciner, and the second heat exchanger is also connected to the gas-solid separator of the calciner; the CaO and CaSO4 removed by the purifier enter the third heat exchanger to preheat the newly added CaCO3; the mixed CaCO3 is first preheated in the second heat exchanger and then enters the calciner; the gas separated by the gas-solid separator of the calciner first enters the second heat exchanger to preheat the CaCO3 and then flows into the solar collector and the first air preheater.

[0015] Furthermore, the present invention provides a tower-type solar and lignite-fired combined power generation system, which may also have the following characteristics: wherein the solar thermal collection device includes a solar absorption tower, a heliostat field, and a heat absorber; the heat absorber is installed on the top of the solar absorption tower; the heliostat field is arranged around the solar absorption tower, and the heliostat field is composed of a plurality of heliostats, each of which is mechanically driven to constantly reflect solar radiation toward the same target point and concentrate it on the heat absorber on the top of the solar absorption tower; after absorbing the concentrated solar radiation, the heat absorber heats the gas.

[0016] Furthermore, the present invention provides a tower-type solar energy and lignite coal-fired combined power generation system, which may also have the following characteristics: wherein, the boiler subsystem also includes a second air preheater; the second air preheater is connected to the lignite predryer, and the flue gas from the flue gas treatment subsystem is first cooled in the second air preheater and then flows into the lignite predryer; the first air preheater, the second air preheater and the furnace are connected in sequence; the air preheated by the first air preheater first enters the second air preheater for secondary preheating, and then enters the furnace for combustion.

[0017] The beneficial effects of the present invention are as follows: the present invention provides a tower-type solar and lignite-fired combined power generation system that integrates calcium cycle desulfurization and decarbonization, lignite drying, and feedwater preheating to solve the problem of integrating coal drying and desulfurization and decarbonization in lignite power plants. Specifically, the use of a solar heat collector can provide high-temperature reaction heat of appropriate energy level to the calciner, thereby saving fuel consumption in the desulfurization and decarbonization process; pre-drying the lignite can improve the quality and low-heating value of the coal, further saving fuel consumption in the desulfurization and decarbonization process; by providing a feedwater / flue gas heat exchanger in parallel with the feedwater heater, steam extraction from the steam turbine can be reduced, thereby improving power generation efficiency; and through integrated optimization of the system, cascade utilization of multiple energy sources can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG1 is an integrated diagram of a tower-type solar energy and lignite-fired combined power generation system according to the present invention. DETAILED DESCRIPTION

[0019] The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0020] As shown in FIG1 , the present invention provides a tower-type solar and lignite-fired combined power generation system, comprising a boiler subsystem 1 , a steam turbine and feedwater preheating subsystem 2 , and a flue gas treatment subsystem 3 .

[0021] The boiler subsystem 1 includes a furnace 11, a lignite predryer 12, and a feedwater / flue gas heat exchanger 13. The furnace 11, flue gas treatment subsystem 3, lignite predryer 12, and feedwater / flue gas heat exchanger 13 are connected in sequence. The lignite predryer 12 is also connected to the furnace 11, forming a flue gas path. The high-temperature flue gas generated by combustion in the furnace 11 first flows into the flue gas treatment subsystem 3 for desulfurization and decarbonization, then flows through the lignite predryer 12 and feedwater / flue gas heat exchanger 13 before being discharged. The lignite is heated and dried by the flue gas in the lignite predryer 12 and then fed to the furnace 11 for combustion.

[0022] The steam turbine and feedwater preheating subsystem 2 includes a steam turbine 21, a condenser 22, and a feedwater heating assembly. The boiler subsystem 1, steam turbine 21, condenser 22, and feedwater heating assembly are connected in sequence to form a steam-feedwater path. Superheated steam from the boiler subsystem 1 enters the steam turbine 21 to perform work. The exhaust steam is collected and cooled in the condenser 22, pressurized by the feedwater pump, and then flows into the feedwater heating assembly for heating. It is then fed into the boiler subsystem 1 to be heated into superheated steam.

[0023] The feedwater / flue gas heat exchanger 13 of the boiler subsystem 1 is connected in parallel with the feedwater heating component to heat the feedwater.

[0024] In a preferred embodiment, the boiler subsystem 1 further includes a steam drum 14, a superheating assembly, and an economizer 16. In the flue gas path, the furnace 11 is connected to the superheating assembly, which in turn is connected to the flue gas treatment subsystem 3, which is connected to the lignite predryer 12 via the economizer 16. The high-temperature flue gas generated by combustion in the furnace 11 first flows through the superheating assembly to be cooled, then enters the flue gas treatment subsystem 3 for desulfurization and decarbonization, and then flows through the economizer 16 to be cooled before entering the lignite predryer 12. The steam turbine and feedwater preheating subsystem 2, economizer 16, steam drum 14, and superheating assembly are sequentially connected, with the steam drum 14 also connected to the furnace 11, forming a feedwater-steam path. The feed water from the steam turbine and feed water preheating subsystem 2 is heated by the economizer 16 and then enters the steam drum 14. The liquid in the steam drum 14 enters the water-cooled wall for heating and then returns to the steam drum 14. The gas in the steam drum 14 first enters the superheating component for heating, and the superheated steam generated enters the steam turbine and feed water preheating subsystem 2 to perform work.

[0025] Specifically, the superheating assembly includes a platen superheater 151, a low-temperature reheater 152, a high-temperature superheater 153, a high-temperature reheater 154, and a low-temperature superheater 155. In the flue gas path, the furnace 11 is sequentially connected to the platen superheater 151, the low-temperature reheater 152, the high-temperature superheater 153, the high-temperature reheater 154, and the low-temperature superheater 155. The low-temperature superheater 155 is further connected to the flue gas treatment subsystem 3. The high-temperature flue gas generated by combustion in the furnace 11 flows sequentially through the platen superheater 151, the low-temperature reheater 152, the high-temperature superheater 153, the high-temperature reheater 154, and the low-temperature superheater 155, where it is cooled and then enters the flue gas treatment subsystem 3 for desulfurization and decarbonization. In the feedwater-steam path, the drum 14 is sequentially connected to the low-temperature superheater 155, the platen superheater 151, and the high-temperature superheater 153. The high-temperature superheater 153 is then connected to the high-pressure cylinder 211 of the steam turbine 21. The gas in the drum 14 is first heated by the low-temperature superheater 155, the platen superheater 151, and the high-temperature superheater 153 before entering the high-pressure cylinder 211 of the steam turbine 21 to perform work. The high-pressure cylinder 211, the low-temperature reheater 152, the high-temperature reheater 154 of the steam turbine 21 are sequentially connected to the intermediate-pressure and low-pressure cylinders 212 of the steam turbine 21. Exhaust steam from the high-pressure cylinder 211 of the steam turbine 21 flows into the low-temperature reheater 152 and the high-temperature reheater 154 to be heated before entering the intermediate-pressure and low-pressure cylinders 212 of the steam turbine 21 to perform work.

[0026] In a preferred embodiment, the steam turbine and feedwater preheating subsystem 2 also includes a steam box 24. The high-temperature superheater 153 is connected to the high-pressure cylinder 211 of the steam turbine 21 via the steam box 24. Superheated steam from the high-temperature superheater 153 first enters the steam box 24 and then enters the high-pressure cylinder 211 of the steam turbine 21 to perform work. The steam box 24 is also connected to a feedwater heating assembly. Superheated steam from the high-temperature superheater 153 also enters the feedwater heating assembly to heat the feedwater.

[0027] In the steam turbine and feedwater preheating subsystem 2, the feedwater heating assembly heats feedwater using extraction steam from the steam turbine 21. The heated, cooled water flows into the condenser 22 as feedwater. Specifically, the feedwater heating assembly includes eight feedwater heaters 23. The high-pressure, intermediate-pressure, and low-pressure cylinders 211, 212, and 213 of the steam turbine 21 are each equipped with eight stages of extraction steam. These eight stages of extraction steam enter the eight feedwater heaters 23 for heating the feedwater. The sixth-eighth stage feedwater heaters 23 are connected in parallel with the feedwater / flue gas heat exchanger 13 of the boiler subsystem 1. That is, a portion of the feedwater from the condenser 22 is heated by the flue gas from the boiler system via the feedwater / flue gas heat exchanger 13, while another portion is preheated in the sixth-eighth stage feedwater heaters 23. The two portions of feedwater are then mixed at the inlet of the fifth-stage feedwater heater 23.

[0028] The flue gas treatment subsystem 3 includes a carbonization furnace 31, a carbonization furnace gas-solid separator 311, a purifier 32, a calciner 33, a calciner gas-solid separator 331, a solar thermal collector 34, and a first air preheater 35. The boiler subsystem 1, the carbonization furnace 31, and the carbonization furnace gas-solid separator 311 are connected in sequence to form a flue gas treatment path. CO2-rich flue gas from the boiler subsystem 1 enters the carbonization furnace 31, reacts with CaO to produce CaCO3 and CaSO4, then enters the carbonization furnace gas-solid separator 311 for gas-solid separation, with the gas then returning to the boiler subsystem 1. The calciner 33 is connected to the lignite predryer 12. The carbonization furnace gas-solid separator 311, the purifier 32, the calciner 33, and the calciner gas-solid separator 331 are connected in sequence. The calciner gas-solid separator 331 is connected to the carbonization furnace 31, the solar thermal collector 34, and the first air preheater 35, respectively, to form a regeneration path. The solids separated by the gas-solid separator 311 of the carbonization furnace enter the purifier 32 for purification, and the obtained CaCO3 is mixed with the newly added CaCO3 and enters the calcining furnace 33. The lignite dried by the lignite pre-dryer 12 enters the calcining furnace 33 to burn and generate heat. The CaCO3 is heated and decomposed into CaO and CO2. After gas-solid separation in the calcining furnace gas-solid separator 331, the solids enter the carbonization furnace 31 for CO2 capture. Part of the gas is heated by the solar energy collector 34 and then returns to the calcining furnace 33 to provide energy. Part of the gas enters the first air preheater 35 to preheat the air entering the furnace 11, and then is compressed and stored.

[0029] In a preferred embodiment, the flue gas treatment subsystem 3 further includes a dust collector 36, a first heat exchanger 37, a second heat exchanger 38, and a third heat exchanger 39. In the flue gas treatment path, the dust collector 36 and the first heat exchanger 37 are sequentially connected between the boiler subsystem 1 and the carbonization furnace 31. The first heat exchanger 37 is also connected to the carbonization furnace gas-solid separator 311. The CO2-rich flue gas from the boiler subsystem 1 first flows through the dust collector 36 for dust removal, then is preheated by the first heat exchanger 37 before entering the carbonization furnace 31. The gas separated by the carbonization furnace gas-solid separator 311 first enters the first heat exchanger 37 to preheat the CO2-rich flue gas from the boiler subsystem 1 before flowing back to the boiler subsystem 1. In the regeneration path, the third heat exchanger 39 is connected to the purifier 32, and the second heat exchanger 38 is connected between the purifier 32 and the calcining furnace 33. The second heat exchanger 38 is also connected to the calcining furnace gas-solid separator 331. The CaO and CaSO₄ removed by purifier 32 enter third heat exchanger 39 to preheat newly added CaCO₃. The mixed CaCO₃ is preheated in second heat exchanger 38 before entering calciner 33. The gas separated by calciner gas-solid separator 331 enters second heat exchanger 38 to preheat the CaCO₃ before flowing into solar collector 34 and first air preheater 35.

[0030] Specifically, the solar thermal collection device 34 includes a solar absorption tower 341, a heliostat field 342, and a heat absorber 343. Heat absorber 343 is mounted on top of the solar absorption tower 341. The heliostat field 342 is arranged around the solar absorption tower 341 and consists of several heliostats. Each heliostat is mechanically driven to constantly reflect solar radiation toward the same target point, concentrating it on the heat absorber 343 atop the solar absorption tower 341. After absorbing the concentrated solar radiation, the heat absorber 343 heats the CO2 from the second heat exchanger 38 to approximately 1200°C. The heated CO2 then enters the calciner 33.

[0031] In a preferred embodiment, the boiler subsystem 1 further includes a second air preheater 17. The second air preheater 17 is disposed between the economizer 16 and the lignite predryer 12. That is, the economizer 16, the second air preheater 17, and the lignite predryer 12 are connected in sequence. The desulfurized and decarbonized flue gas from the flue gas treatment subsystem 3 is first preheated with feed water in the economizer 16, then cooled in the second air preheater 17, and then flows into the lignite predryer 12. The first air preheater 35, the second air preheater 17, and the furnace 11 are connected in sequence. The air preheated by the first air preheater 35 first enters the second air preheater 17 for secondary preheating by the flue gas, and then enters the furnace 11 for combustion.

[0032] The working process of the tower solar and lignite coal-fired combined power generation system provided by the present invention is as follows:

[0033] Lignite burns in the furnace 11, generating a large amount of high-temperature flue gas at the outlet of the furnace 11. The high-temperature flue gas flows through the screen superheater 151, the low-temperature reheater 152, the high-temperature superheater 153, the high-temperature reheater 154 and the low-temperature superheater 155 in sequence. The flue gas at the outlet of the low-temperature superheater 155 enters the flue gas treatment subsystem 3 for dust removal, desulfurization and decarbonization. The treated flue gas returns to the boiler subsystem 1 and continues to flow through the economizer 16, the air preheater, the lignite predryer 12 and the flue gas / feedwater heater 23, and is finally discharged into the atmosphere through the chimney.

[0034] At the same time, the feed water from the steam turbine and the feed water preheating subsystem 2 is heated by the economizer 16 and then enters the steam drum 14. The liquid in the steam drum 14 enters the water-cooled wall for heating and then returns to the steam drum 14. The gas in the steam drum 14 enters the low-temperature superheater 155, the screen superheater 151 and the high-temperature superheater 153 for heating in turn. The high-temperature and high-pressure steam generated enters the high-pressure cylinder 211 of the steam turbine 21 to perform work.

[0035] The low-temperature reheater 152 and the high-temperature reheater 154 in the boiler subsystem 1 are used to heat the exhaust steam from the high-pressure cylinder 211 of the turbine 21. The exhaust steam is heated by the low-temperature reheater 152 and the high-temperature reheater 154 in turn and then enters the medium-pressure cylinder and the low-pressure cylinder 212 of the turbine 21 to perform work.

[0036] The lignite predryer 12 in the boiler subsystem 1 predries the lignite by recovering the waste heat in the flue gas. The predried lignite is divided into two parts, one part enters the furnace 11 of the boiler subsystem 1 for combustion, and the other part enters the calciner 33 of the flue gas treatment subsystem 3 for combustion.

[0037] The second air preheater 17 of the boiler subsystem 1 is used to preheat the air preheated by the first air preheater 35 of the flue gas treatment subsystem 3. The preheated air enters the furnace 11 and burns with the dried lignite.

[0038] The feedwater / flue gas heat exchanger 13 of the boiler subsystem 1 is connected in parallel to the steam turbine 21 and the feedwater heaters 23 No. 6-8 in the heat recovery system to preheat part of the condensate.

[0039] In the steam turbine and feedwater preheating subsystem 2, feedwater from the condenser 22 is pressurized by the feedwater pump and preheated by eight feedwater heaters 23 before entering the boiler subsystem 1 for heating. Superheated steam from the high-temperature superheater 153 of the boiler subsystem 1 enters the high-pressure cylinder 211 of the steam turbine 21, where it expands and produces work. After this work, exhaust steam from the high-pressure cylinder 211 enters the low-temperature reheater 152 and high-temperature reheater 154 of the boiler subsystem 1 for reheating. Reheated steam from the high-temperature reheater 154 of the boiler subsystem 1 returns to the intermediate-pressure cylinder of the steam turbine 21, where it expands and produces work in both the intermediate-pressure cylinder and the high-pressure cylinder 211. Finally, the exhaust steam is collected and cooled in the condenser 22. To improve cycle efficiency, eight stages of steam extraction are provided in each of the high-pressure, intermediate-pressure, and low-pressure cylinders 211, 212. These extraction steam enters eight stages of feedwater heaters 23 to heat the feedwater. After heating, the extracted steam condenses into water and flows into the condenser 22. In addition, the 6th-8th stage feedwater heaters 23 are connected in parallel to the feedwater / flue gas heat exchanger 13 of the boiler subsystem 1. A portion of the feedwater for the condenser 22 is heated by the flue gas from the boiler system via the feedwater / flue gas heat exchanger 13, while the remaining portion is preheated in the 6th-8th stage feedwater heaters 23. The two portions are then mixed at the inlet of the 5th stage feedwater heater 23.

[0040] The flue gas (i.e., CO2-rich flue gas) discharged from the low-temperature superheater 155 in boiler subsystem 1 passes through the dust collector 36 for dust removal and is then preheated by the first heat exchanger 37. The CO2-rich flue gas then reacts with CaO in the carbonization furnace 31 at 650°C to produce CaCO3 and CaSO4. The gas-solid mixture at the outlet of the carbonization furnace 31 is then separated into gas and solid by the carbonization furnace gas-solid separator 311. The gas, now CO2-lean flue gas, passes through the first heat exchanger 37 to release heat and preheat the CO2-rich flue gas before returning to the economizer 16 of boiler subsystem 1. The solids primarily consist of CaCO₃, CaSO₄, and unreacted CaO. Deactivated CaO and CaSO₄ are first removed in the purifier 32. This portion of solids releases heat in the third heat exchanger 39 to preheat newly added CaCO₃. The remaining purified solids are then mixed with the newly added CaCO₃ preheated in the third heat exchanger 39. The mixed solids are preheated with pure CO₂ in the second heat exchanger 38 before entering the calciner 33. The temperature in the calciner 33 is 1000°C, where the CaCO₃ decomposes into CaO and CO₂. The gas-solid mixture at the outlet of the calciner 33 is separated into gas and solids by the calciner gas-solid separator 331. The solids then enter the carbonization furnace 31 for CO₂ capture, marking a new cycle. The gas, pure CO₂, releases heat in the second heat exchanger 38 and is divided into two parts. One part enters the first air preheater 35 to preheat air, where it is then compressed and stored. The other part, heated as a heat transfer fluid by the solar collector 34, then returns to the calciner 33. The energy required by calciner 33 is supplied by two sources: one from the combustion of dried lignite in oxygen-rich conditions, and the other from the heating of CO2 by solar thermal collector 34. The heat absorber 343 of solar thermal collector 34 absorbs concentrated solar energy and heats the CO2 from second heat exchanger 38 to approximately 1200°C. The heated CO2 then enters calciner 33.

[0041] In the present invention, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. In addition, the reagents, materials and operating procedures used herein are those widely used in the corresponding fields.

[0042] It should be noted that the terms such as "upper", "lower", "left", "right", "front", "back", etc. cited in the invention are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0043] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A tower solar energy and lignite coal-fired combined power generation system, characterized in that: It includes a boiler subsystem, a steam turbine and a feed water preheating subsystem, and a flue gas treatment subsystem; The boiler subsystem includes a furnace, a lignite pre-dryer and a feed water / flue gas heat exchanger; The furnace, the flue gas treatment subsystem, the lignite pre-dryer and the feed water / flue gas heat exchanger are connected in sequence, and the lignite pre-dryer is also connected to the furnace; the high-temperature flue gas generated by the combustion in the furnace first flows into the flue gas treatment subsystem for desulfurization and decarbonization, and then flows through the lignite pre-dryer and the feed water / flue gas heat exchanger in sequence and is finally discharged; the lignite is heated and dried by the flue gas in the lignite pre-dryer and then sent to the furnace for combustion; The steam turbine and the feed water preheating subsystem include a steam turbine, a condenser and a feed water heating component; The boiler subsystem, the steam turbine, the condenser and the feed water heating component are connected in sequence; the superheated steam from the boiler subsystem enters the steam turbine to do work, the exhaust steam is collected and cooled in the condenser, pressurized by the feed water pump and then flows into the feed water heating component to be heated, and then sent back to the boiler subsystem to be heated into superheated steam; The feed water / flue gas heat exchanger is connected in parallel with the feed water heating component to heat the feed water.

2. The tower solar energy and lignite coal-fired combined power generation system according to claim 1, characterized in that: Among them, The boiler subsystem further includes a steam drum, a superheating component and an economizer; The furnace is connected to the superheating component, the superheating component is then connected to the flue gas treatment subsystem, and the flue gas treatment subsystem is connected to the lignite pre-dryer through the economizer; the high-temperature flue gas generated by the combustion in the furnace first flows through the superheating component and is cooled, then enters the flue gas treatment subsystem for desulfurization and decarbonization, and then flows through the economizer and is cooled before entering the lignite pre-dryer; The steam turbine and the feed water preheating subsystem, the economizer, the steam drum and the superheating component are connected in sequence, and the steam drum is also connected to the furnace; the feed water from the steam turbine and the feed water preheating subsystem is heated by the economizer and then enters the steam drum, The liquid in the steam drum enters the water wall to be heated and then returns to the steam drum, and the gas in the steam drum first enters the superheating component to be heated, and the generated superheated steam enters the steam turbine and the feed water preheating subsystem to do work.

3. The tower solar energy and lignite coal-fired combined power generation system according to claim 2, characterized in that: Among them, The superheating component includes a platen superheater, a low-temperature reheater, a high-temperature superheater, a high-temperature reheater and a low-temperature superheater; The furnace is connected to the platen superheater, the low-temperature reheater, the high-temperature superheater, the high-temperature reheater and the low-temperature superheater in sequence, and the low-temperature superheater is then connected to the flue gas treatment subsystem; the high-temperature flue gas generated by the combustion in the furnace flows through the platen superheater, the low-temperature reheater, the high-temperature superheater, the high-temperature reheater and the low-temperature superheater in sequence and is cooled, and then enters the flue gas treatment subsystem for desulfurization and decarbonization; The steam drum is connected to the low-temperature superheater, the platen superheater and the high-temperature superheater in sequence, and the high-temperature superheater is then connected to the high-pressure cylinder of the steam turbine; the gas in the steam drum first passes through the low-temperature superheater, the platen superheater and the high-temperature superheater in sequence to be heated, and then enters the high-pressure cylinder of the steam turbine to do work; The high-pressure cylinder of the steam turbine, the low-temperature reheater, the high-temperature reheater, and the intermediate-pressure cylinder and the low-pressure cylinder of the steam turbine are connected in sequence; the exhaust steam from the high-pressure cylinder of the steam turbine flows into the low-temperature reheater and the high-temperature reheater in sequence to be heated, and then enters the intermediate-pressure cylinder and the low-pressure cylinder of the steam turbine to do work.

4. The tower solar energy and lignite coal-fired combined power generation system according to claim 3, characterized in that: Among them, The steam turbine and the feed water preheating subsystem further include a steam chest; The high-temperature superheater is connected to the high-pressure cylinder of the steam turbine through the steam chest; the superheated steam from the high-temperature superheater first enters the steam chest, and then enters the high-pressure cylinder of the steam turbine to do work; The steam chest is also connected to the feed water heating assembly; the superheated steam enters the feed water heating assembly to heat the feed water.

5. The tower solar energy and lignite coal-fired combined power generation system according to claim 1, characterized in that: Among them, In the steam turbine and the feed water preheating subsystem, the feed water heating assembly heats the feed water by the extraction steam of the steam turbine.

6. The tower solar energy and lignite coal-fired combined power generation system according to claim 5, characterized in that: Among them, The feed water heating assembly includes eight feed water heaters, and the high-pressure cylinder, the intermediate-pressure cylinder and the low-pressure cylinder of the steam turbine are respectively provided with eight-stage extraction steam, and the eight-stage extraction steam respectively enters the eight-stage feed water heaters to heat the feed water; The sixth to eighth feed water heaters are connected in parallel with the feed water / flue gas heat exchanger of the boiler subsystem.

7. The tower solar energy and lignite coal-fired combined power generation system according to claim 1, characterized in that: Among them, The flue gas treatment subsystem includes a carbonization furnace, a carbonization furnace gas-solid separator, a purifier, a calcination furnace, a calcination furnace gas-solid separator, a solar energy collector and a first air preheater; The boiler subsystem, the carbonization furnace and the carbonization furnace gas-solid separator are connected in sequence; the flue gas from the boiler subsystem enters the carbonization furnace, reacts with CaO to generate CaCO3 and CaSO4, and then enters the carbonization furnace gas-solid separator for gas-solid separation, and the gas returns to the boiler subsystem; The calcination furnace is connected to the lignite pre-dryer, the carbonization furnace gas-solid separator, the purifier, the calcination furnace and the calcination furnace gas-solid separator are connected in sequence, and the calcination furnace gas-solid separator is respectively connected to the carbonization furnace, the solar energy collector and the first air preheater; the solid separated by the carbonization furnace gas-solid separator enters the purifier for purification, and the obtained CaCO3 is mixed with the newly supplemented CaCO3 and then enters the calcination furnace. The lignite dried by the lignite pre-dryer enters the calcination furnace to burn and generate heat, and CaCO3 is heated and decomposed into CaO and CO2. After being separated by the calcination furnace gas-solid separator, the solid enters the carbonization furnace, and part of the gas is heated by the solar energy collector and then returns to the calcination furnace to provide energy, and part of the gas enters the first air preheater to preheat the air entering the furnace.

8. The tower solar energy and lignite coal-fired combined power generation system according to claim 7, characterized in that: Among them, The flue gas treatment subsystem further includes a dust collector, a first heat exchanger, a second heat exchanger and a third heat exchanger; The dust collector and the first heat exchanger are sequentially connected between the boiler subsystem and the carbonization furnace. The first heat exchanger is also connected to the gas-solid separator of the carbonization furnace. The flue gas from the boiler subsystem first flows through the dust collector for dust removal, then is preheated by the first heat exchanger, and then enters the carbonization furnace. The gas separated by the gas-solid separator of the carbonization furnace first enters the first heat exchanger to preheat the flue gas and then flows back to the boiler subsystem. The third heat exchanger is connected to the purifier. The second heat exchanger is connected between the purifier and the calcination furnace. The second heat exchanger is also connected to the gas-solid separator of the calcination furnace. The CaO and CaSO4 removed by the purification of the purifier enter the third heat exchanger to preheat the newly added CaCO3. The mixed CaCO3 is first preheated in the second heat exchanger and then enters the calcination furnace. The gas separated by the gas-solid separator of the calcination furnace first enters the second heat exchanger to preheat the CaCO3 and then flows into the solar collector and the first air preheater.

9. The tower-type solar energy and lignite coal-fired combined power generation system according to claim 7, It is characterized in that: Among them, the solar collector includes a solar absorption tower, a heliostat field, and a heat absorber; The heat absorber is installed on the top of the solar absorption tower; The heliostat field is arranged around the solar absorption tower. The heliostat field is composed of several heliostats. Each heliostat reflects solar radiation constantly towards the same target point by a mechanical drive method and converges on the heat absorber at the top of the solar absorption tower; After absorbing the solar concentrated light, the heat absorber heats the gas.

10. The tower solar and lignite coal-fired combined power generation system according to claim 7, It is characterized in that: Among them, the boiler subsystem further includes a second air preheater; The second air preheater is connected to the lignite pre-dryer. The flue gas from the flue gas treatment subsystem is first cooled in the second air preheater and then flows into the lignite pre-dryer; The first air preheater, the second air preheater, and the furnace are sequentially connected. The air preheated by the first air preheater first enters the second air preheater for secondary preheating and then enters the furnace for combustion.

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