Flue gas pollutant treatment system coupled with thermal power flexible peak regulation and control method thereof

Abstract

The invention discloses a thermal power coupling flexible peak regulation flue gas pollutant treatment system and a control method thereof.The thermal power coupling flexible peak regulation flue gas pollutant treatment system comprises a flue gas and air system, a water vapor system and a pollutant treatment system, the flue gas and air system comprises a boiler, and the water vapor system communicates with the boiler; the water vapor system and the flue gas and air system jointly form a thermal power main engine thermal power production system, the pollutant treatment system is communicated with the flue gas and air system, the pollutant treatment system is used for receiving flue gas generated by the flue gas and air system, and the water vapor system is suitable for providing a heat source for a catalyst in the regeneration tower. According to the flue gas pollutant treatment system coupled with thermal power and flexible peak regulation, flue gas pollutant treatment of low-load stability and peak regulation flexibility of a thermal power generating unit is improved in a mode that a regenerative heat source is coupled with a water vapor system.

Description

Technical Field

[0001] This invention relates to the field of thermal power generation technology, and in particular to a flue gas pollutant treatment system and control method coupled with flexible peak shaving of thermal power. Background Technology

[0002] As the proportion of renewable energy installed capacity in the total installed power capacity continues to increase, the role of thermal power units is gradually shifting from "main power source" to "regulatory power source." This requires thermal power units to meet the peak-shaving requirements of "being able to meet grid needs when required and quickly adjusting to load fluctuations." Currently, the flexible peak-shaving capability of thermal power units faces three technical challenges: the physical limits of stable combustion under low loads, the system inertia of rapid load increases, and the uncontrolled emission of flue gas pollutants under drastic load fluctuations. These technical difficulties severely restrict the supporting role of thermal power units in the construction of new power systems.

[0003] First, deep peak shaving in thermal power units faces the challenge of stable combustion technology under low load conditions. When the load drops to 30% or even 20% of the rated value, the furnace temperature drops significantly, the pulverized coal concentration distribution becomes uneven, the flame stability deteriorates, and there is a possibility of flameout. Traditional combustion organization methods face the risk of failure. This not only means unplanned unit shutdowns but may also lead to serious equipment safety accidents. From a technical perspective, combustion power weakens under low load conditions, and the burnout rate decreases significantly. Research data shows that when the load drops from 100% to 40%, the pulverized coal burnout time increases by about 60%, and the carbon content of fly ash increases by nearly two times. This incomplete combustion not only leads to a decrease in boiler efficiency but also triggers a series of chain reactions: increased ash accumulation in the tail flue, increased temperature difference on the heating surface, uneven distribution of thermal stress, and long-term operation will accelerate equipment fatigue damage and shorten the life of key components.

[0004] Secondly, flexible peak shaving for thermal power units faces the dynamic challenge of rapidly increasing and decreasing loads. Traditional thermal power units, as massive thermal systems, possess enormous thermal inertia, inherently lacking in response speed and flexibility. It typically takes several hours to reach full load from a cold start. Even under hot conditions, the load ramp-up rate is constrained by physicochemical factors such as fuel supply rate, combustion heat transfer rate, water-steam working fluid transport rate, and thermal strain rate of metallic materials. The core contradiction lies in the mismatch of dynamic characteristics between various systems. During rapid load changes, the control coupling relationships between subsystems become extremely complex. Dozens of control variables, such as feedwater flow, fuel quantity, and air supply, interact with each other, rendering traditional PID control strategies inadequate under rapid load changes. On the boiler side, the steam-water system has a large heat capacity and slow response; on the turbine side, metallic components are extremely sensitive to temperature change rates, and excessively rapid heating will generate enormous thermal stress, threatening the safety of critical components such as the rotor and cylinder. This incoordination problem between systems is amplified as the unit's ramp-up rate increases.

[0005] Furthermore, achieving stable and compliant emissions of pollutants for thermal power units under low-load and rapidly changing load conditions presents another challenge. While thermal power units have fully achieved ultra-low emissions, this achievement faces severe challenges under flexible peak-shaving conditions. Nitrogen oxide (NOx) control is paramount. Selective catalytic reduction (SCR) denitrification systems have strict requirements on flue gas temperature, typically requiring temperatures above 300℃ to ensure denitrification efficiency. Under low-load operation, flue gas temperature may drop below 280℃. If ammonia injection continues at this temperature, not only will denitrification efficiency plummet, but unreacted ammonia will also react with sulfur dioxide in the flue gas to form ammonium bisulfate, causing blockage of the air preheater and creating a vicious cycle. Particulate matter and sulfur dioxide emissions also face difficulties. Electrostatic precipitators experience reduced dust removal efficiency at low flue gas temperatures, and the electrostatic field's charging effect deteriorates; wet desulfurization systems experience reduced circulating slurry volume and decreased mass transfer efficiency under low loads, making it difficult to guarantee desulfurization efficiency. Frequent load fluctuations cause environmental protection facilities to operate under off-design conditions for extended periods, affecting equipment reliability and lifespan, and significantly increasing maintenance costs. The essence of the current emission control dilemma lies in the mismatch between the design philosophy of environmental protection facilities and operational needs. Existing facilities were originally designed for stable operation under rated load, but now they are required to operate "around the clock" across a wide load range. When environmental protection red lines meet peak-shaving requirements, thermal power plants are forced to make difficult trade-offs between emission targets and grid commands. This dilemma exposes the deep-seated contradiction between the current environmental protection technology system and the need for flexible operation. Summary of the Invention

[0006] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one object of this invention is to propose a flue gas pollutant treatment system coupled with flexible peak shaving in thermal power plants. This system improves the low-load stability and peak-shaving flexibility of thermal power units by coupling a regenerated heat source with a steam-water system.

[0007] According to an embodiment of the present invention, a flue gas pollutant treatment system for coupled thermal power with flexible peak shaving includes: a flue gas system, which includes a boiler; a steam-water system, which is connected to the boiler, and together with the flue gas system, forms a thermal power main unit thermal production system; and a pollutant treatment system, which is connected to the flue gas system and is used to receive the flue gas generated by the flue gas system. The steam-water system is adapted to provide a heat source for the catalyst in the regeneration tower. The steam-water system includes a steam turbine, a reheater, a condenser, a low-pressure feedwater pump, a first low-pressure heater, a second low-pressure heater, a deaerator, a high-pressure feedwater pump, and a high-pressure heater. The steam turbine includes a high-pressure cylinder and a low-pressure cylinder. One path of the high-pressure cylinder is connected to the high-pressure heater via a regenerative extraction steam pipe. The regenerative extraction steam pipe is equipped with a sixth valve, which is used to adjust the extraction steam volume. The other path of the high-pressure cylinder is connected to the reheater via a pipe. The reheater is connected to the steam-gas heat exchanger of the pollutant treatment system via a first pipe. A branch pipe connects the first pipeline and the low-pressure cylinder, and the first branch pipe is equipped with a first valve to regulate the main steam flow. The low-pressure cylinder is connected to the high-pressure cylinder. One path of the low-pressure cylinder is connected to the first low-pressure heater via the condenser and the low-pressure feedwater pump. The other path of the low-pressure cylinder is connected to the second low-pressure heater via a regenerative steam extraction pipeline. The regenerative steam extraction pipeline is equipped with a fifth valve to regulate the extraction volume. The second low-pressure heater is connected downstream of the first low-pressure heater. The steam-gas heat exchanger is connected to the first low-pressure heater via a second pipeline. The first pipeline and the second pipeline are connected via a second branch pipe. The connection point between the first branch pipe and the first pipeline is located upstream of the connection point between the second branch pipe and the first pipeline. The second branch pipe is equipped with a third valve. The steam inlet of the steam-gas heat exchanger is equipped with a second valve. The steam outlet of the steam-gas heat exchanger is equipped with a fourth valve. The steam outlet of the low-pressure heater is connected to the boiler via the deaerator, the high-pressure feedwater pump, and the high-pressure heater in sequence.

[0008] In some embodiments of the present invention, the flue gas system further includes a high-temperature denitrification device and a dust collector. The boiler, the high-temperature denitrification device and the dust collector are connected in sequence through a flue. The flue gas generated by the boiler is suitable to enter the pollutant treatment system by passing through the high-temperature denitrification device and the dust collector in sequence.

[0009] In some embodiments of the present invention, the pollutant treatment system further includes: a purification tower, a regeneration tower, an ammonia injection device, and a vibrating screen. The flue gas generated by the flue gas system enters the purification tower after ammonia is injected into it by the ammonia injection device. The purification tower contains a catalyst, which is suitable for adsorbing and removing SO2 from the flue gas. The NOx in the flue gas is suitable for being catalytically reduced by the catalyst. The saturated catalyst is suitable for being transported to the regeneration tower for thermal regeneration. After being regenerated in the regeneration tower, the catalyst is cooled and sieved by the vibrating screen. The portion of the catalyst with qualified particle size is suitable for being transported to the purification tower.

[0010] In some embodiments of the present invention, the regeneration tower includes a preheating section, a heating section, a constant temperature section, and a cooling section. The preheating section is used for preheating the catalyst and controlling the catalyst level. The heating section is used to heat the catalyst so that the temperature meets the catalyst regeneration requirements. The constant temperature section serves as the catalyst regeneration site to ensure that the catalyst regeneration residence time meets the requirements. The cooling section is used to cool the regenerated catalyst and meet the pollutant removal requirements. The water vapor system is adapted to provide a heat source for the heating section.

[0011] In some embodiments of the present invention, the pollutant treatment system further includes a steam-gas heat exchanger and a high-temperature air fan, wherein the heating section, the high-temperature air fan and the steam-gas heat exchanger are connected by a high-temperature air duct to form a hot air circulation loop.

[0012] In some embodiments of the present invention, the pollutant treatment system further includes a sulfur resource recovery device, which is connected to the constant temperature section and is used to recover SO2.

[0013] In some embodiments of the present invention, the catalyst is a carbon-based catalyst, which includes activated coke or activated carbon.

[0014] The present invention also proposes a control method for a flue gas pollutant treatment system coupled with flexible peak shaving of thermal power plants in the above embodiments, comprising: acquiring the unit operating status; when the unit is operating at low load, reducing the opening of the first valve, increasing the opening of the second valve and the fourth valve, while increasing the catalyst material circulation rate and / or catalyst regeneration temperature in the pollutant treatment system, increasing the heat exchange load of the steam-gas heat exchanger, and adjusting the opening of the third valve to keep the outlet feedwater enthalpy of the first low-pressure heater stable.

[0015] In some embodiments of the present invention, the control method of the flue gas pollutant treatment system coupled with flexible peak shaving of thermal power further includes: when the unit is operating under normal conditions, controlling the opening of the first valve, the fifth valve, and the sixth valve to meet the power output demand of the generator unit, closing the third valve, and controlling the opening of the second valve and the fourth valve to meet the heat exchange load demand of the steam-gas heat exchanger, wherein the heat exchange load is positively correlated with the concentration of SO2 in the flue gas and the regeneration set temperature, and satisfies:

[0016] Where: Q is the heat load of the steam-gas heat exchanger; c is the specific heat capacity of the catalyst; and These are the average temperatures of the catalyst at the inlet and outlet of the heating section, respectively. The heat of physical adsorption of SO2 in flue gas by the catalyst; The heat of decomposition of sulfuric acid generated from the chemical adsorption of SO2 in the catalyst; The heat dissipation of the heating section and the constant temperature section is calculated. When the enthalpy of the feedwater at the outlet of the low-pressure heater is lower than the set enthalpy value of the unit feedwater, the third valve can be opened to adjust the feedwater enthalpy value.

[0017] In some embodiments of the present invention, the control method of the flue gas pollutant treatment system coupled with flexible peak shaving of thermal power further includes: when the unit is ramping up, reducing the opening of the second valve and the fourth valve, and increasing the opening of the first valve. The adjustment rate of the opening of the first valve is determined based on the difference between the ramping output of other peak shaving measures of the generator unit and the required ramping capacity. At the same time, the opening of the third valve is increased to ensure the stability of the enthalpy value of the feedwater at the outlet of the first low-pressure heater.

[0018] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of a flue gas pollutant treatment system coupled with flexible peak shaving of thermal power plants, according to some embodiments of the present invention.

[0020] Figure 2 This is a schematic diagram of a water vapor system according to some embodiments of the present invention.

[0021] Figure label: 1. Flue gas system; 11. Boiler; 12. High-temperature denitrification device; 13. Dust collector; 2. Steam-water system; 21. Steam turbine; 21-1. High-pressure cylinder; 21-2. Low-pressure cylinder; 22. Reheater; 23. Condenser; 24. Low-pressure feedwater pump; 25. First low-pressure heater; 26. Second low-pressure reheater; 27. Deaerator; 28. High-pressure feedwater pump; 29. ​​High-pressure heater; 2-1. First valve; 2-2. Second valve; 2-3. Third valve; 2-4. Fourth valve; 2-5. Fifth valve; 2-6. Sixth valve; 3. Pollutant treatment system; 31. Purification tower; 32. Regeneration tower; 32-1. Preparatory section; 32-2. Heating section; 32-3. Constant temperature section; 32-4. Cooling section; 321. High temperature air fan; 322. Steam-gas heat exchanger; 323. Cooling fan; 33. Vibrating screen; 34. Sulfur resource utilization device; 35. Ammonia injection device. Detailed Implementation

[0022] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0023] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," and "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] The following is for reference. Figure 1 and Figure 2This invention describes a flue gas pollutant treatment system for flexible peak shaving of thermal power plants, based on an embodiment of the present invention.

[0026] According to an embodiment of the present invention, a flue gas pollutant treatment system for coupled thermal power with flexible peak shaving includes a flue gas system 1, a steam-water system 2, and a pollutant treatment system 3. The flue gas system 1 includes a boiler 11. The steam-water system 2 is connected to the boiler 11, and the steam-water system 2 and the flue gas system 1 together form a thermal power unit thermal production system. The pollutant treatment system 3 is connected to the flue gas system 1 and is used to receive the flue gas generated by the flue gas system 1. The steam-water system 2 is adapted to provide a heat source for the catalyst in the regeneration tower 32. The steam-water system 2 includes a steam turbine 21 and a reheater. 22. Condenser, low-pressure feedwater pump 24, first low-pressure heater 25, second low-pressure heater, deaerator 27, high-pressure feedwater pump 28, and high-pressure heater 29. The turbine 21 includes a high-pressure cylinder 21-1 and a low-pressure cylinder 21-2. One path of the high-pressure cylinder 21-1 is connected to the high-pressure heater 29 via a regenerative extraction steam pipe. The regenerative extraction steam pipe is equipped with a sixth valve 2-6, which is used to regulate the extraction steam volume. The other path of the high-pressure cylinder 21-1 is connected to the reheater 22 via a pipe. The reheater 22 is connected to the pollutant treatment system 3 via a first pipeline. The steam-gas heat exchanger 322 is connected. The first branch pipe connects to the first pipeline and the low-pressure cylinder 21-2. The first branch pipe is equipped with the first valve 2-1 to regulate the main steam flow. The low-pressure cylinder 21-2 is connected to the high-pressure cylinder 21-1. One path of the low-pressure cylinder 21-2 is connected to the first low-pressure heater 25 via the condenser and the low-pressure feedwater pump 24. The other path of the low-pressure cylinder 21-2 is connected to the second low-pressure heater via the regenerative extraction steam pipeline. The regenerative extraction steam pipeline is equipped with the fifth valve 2-5 to regulate the extraction rate. The second low-pressure heater is connected downstream of the first low-pressure heater 25. The gas-gas heat exchanger 322 is connected to the first low-pressure heater 25 through the second pipeline. The first pipeline and the second pipeline are connected through the second branch pipe. The connection point between the first branch pipe and the first pipeline is located upstream of the connection point between the second branch pipe and the first pipeline. The second branch pipe is equipped with a third valve 2-3. The steam inlet of the gas-gas heat exchanger 322 is equipped with a second valve 2-2. The steam outlet of the gas-gas heat exchanger 322 is equipped with a fourth valve 2-4. The steam outlet of the low-pressure heater is connected to the boiler 11 in sequence through the deaerator 27, the high-pressure feed water pump 28 and the high-pressure heater 29.

[0027] In other words, the flue gas pollutant treatment system coupled with flexible peak shaving of thermal power mainly consists of a flue gas system 11, a water vapor system 22, and a pollutant treatment system 33. The flue gas system 11 and the water vapor system 22 together form the thermal power generation system of the thermal power unit. The flue gas generated by the flue gas system 1 is treated by the pollutant treatment system 33 and then discharged in compliance with standards. The water vapor system 22 provides a heat source for the regeneration of the catalyst in the pollutant treatment system 33, ensuring its stable pollutant removal efficiency performance.

[0028] The heat fluid in the steam-gas heat exchanger 322 is reheat steam. Its steam inlet is connected to the steam outlet pipe of the reheater 2222, and the steam flow is controlled by the second valve 2-2. The steam outlet is connected to the steam inlet pipe of the low-pressure heater 25, and the steam flow is controlled by the fourth valve 2-4.

[0029] In some embodiments of the present invention, the flue gas system 1 further includes a high-temperature denitrification device 12 and a dust collector 13. The boiler 11, the high-temperature denitrification device 12, and the dust collector 13 are connected in sequence through a flue. The flue gas generated by the boiler 11 is suitable to enter the pollutant treatment system 3 after passing through the high-temperature denitrification device 12 and the dust collector 13 in sequence. That is, the flue gas from the boiler 11 enters the pollutant treatment system 3 after high-temperature denitrification and dust removal.

[0030] In some embodiments of the present invention, the pollutant treatment system 3 further includes: a purification tower 31, a regeneration tower 32, an ammonia injection device, and a vibrating screen 33. The flue gas generated by the flue gas system 1 enters the purification tower 31 after ammonia is injected by the ammonia injection device. The purification tower 31 contains a catalyst, which is suitable for adsorbing and removing SO2 in the flue gas. The NOx in the flue gas is suitable for being catalytically reduced by the catalyst. The saturated catalyst is suitable for being transported to the regeneration tower 32 for thermal regeneration. After being cooled and screened by the vibrating screen 33, the portion of the catalyst with qualified particle size is suitable for being transported to the purification tower 31.

[0031] In other words, the pollutant treatment system 3 adopts a dry carbon-based catalytic method for the synergistic removal of multiple pollutants. The pollutant treatment system 3 forms a catalyst material circulation system through material conveying and flow control equipment. The flue gas generated by the flue gas system 1 enters the purification tower 31 after being injected with ammonia by the ammonia injection device. SO2 in the flue gas is adsorbed and removed by the catalyst, and NOx is catalytically reduced by the catalyst. The saturated catalyst is transported to the regeneration tower 32 for thermal regeneration. After the regenerated catalyst is cooled and screened, the portion with qualified particle size is transported back to the purification tower 31 to continue to participate in the pollutant removal reaction, forming a catalyst material utilization cycle.

[0032] In some embodiments of the present invention, the regeneration tower 32 includes a preparatory section 32-1, a heating section 32-2, a constant temperature section 32-3, and a cooling section 32-4. The preparatory section 32-1 is used for preheating the catalyst and controlling the catalyst level. The heating section 32-2 is used to heat the catalyst to ensure that the temperature meets the requirements for catalyst regeneration. The constant temperature section 32-3 serves as the catalyst regeneration site to ensure that the catalyst regeneration residence time meets the requirements. The cooling section 32-4 is used to cool the regenerated catalyst and meet the requirements for pollutant removal. A water vapor system 2 is adapted to provide a heat source for the heating section 32-2. A cooling fan 323 is used to provide cooling air to the cooling section 32-4.

[0033] In some embodiments of the present invention, the pollutant treatment system 3 further includes a steam-gas heat exchanger 322 and a high-temperature air fan 321. The heating section 32-2, the high-temperature air fan 321 and the steam-gas heat exchanger 322 are connected by a high-temperature air pipe to form a hot air circulation loop.

[0034] In some embodiments of the present invention, the pollutant treatment system 3 further includes a sulfur resource recovery device 34, which is connected to the constant temperature section 32-3 and is used to recover SO2.

[0035] In some embodiments of the present invention, the catalyst is a carbon-based catalyst, which includes activated coke or activated carbon.

[0036] The present invention also proposes a control method for a flue gas pollutant treatment system coupled with flexible peak shaving of thermal power plants in the above embodiments, comprising: acquiring the unit operating status; when the unit is operating at low load, reducing the opening of the first valve 2-1, increasing the opening of the second valve 2-2 and the fourth valve 2-4, while increasing the catalyst material circulation rate and / or catalyst regeneration temperature in the pollutant treatment system 3, increasing the heat exchange load of the steam-gas heat exchanger 322, and adjusting the opening of the third valve 2-3 to keep the outlet feedwater enthalpy of the first low-pressure heater 25 stable.

[0037] The advantages of the above method are as follows: When the unit is operating at low load, the combustion conditions of boiler 11 are poor, coal consumption is high, and economic efficiency is poor. The concentration and composition of pollutants in the flue gas of the flue gas system 11 become unstable, affecting the stable operation of the unit and the compliance of pollutant emissions. Through the above operation, on the one hand, by increasing the heat exchange load of the steam-gas heat exchanger 322, the minimum load of the unit is increased, which promotes the improvement of the combustion conditions of boiler 11, reduces coal consumption, and improves economic efficiency; on the other hand, the heat source during the low load operation of the unit is fully utilized to accelerate the desorption process of pollutants accumulated in the catalyst of the pollutant treatment system 3 during the rapid load increase phase of the unit, while improving the catalyst regeneration efficiency, providing a reserve for the effective removal of pollutants during the rapid load increase process of the main system again.

[0038] In some embodiments of the present invention, the control method of the flue gas pollutant treatment system coupled with flexible peak shaving of thermal power further includes: when the unit is operating under normal conditions, controlling the opening of the first valve 2-1, the fifth valve 2-5, and the sixth valve 2-6 to meet the power output requirements of the generator unit, closing the third valve 2-3, and controlling the opening of the second valve 2-2 and the fourth valve 2-4 to meet the heat exchange load requirements of the steam-gas heat exchanger 322, wherein the heat exchange load is positively correlated with the concentration of SO2 in the flue gas and the regeneration set temperature, and satisfies:

[0039] Where: Q is the heat load of the steam-gas heat exchanger 322; c is the specific heat capacity of the catalyst; and These are the average temperatures of the catalyst at the inlet and outlet of heating section 32-2, respectively. The heat of physical adsorption of SO2 in flue gas by the catalyst; The heat of decomposition of sulfuric acid generated from the chemical adsorption of SO2 in the catalyst; The heat dissipation of the heating section 32-2 and the constant temperature section 32-3 is as follows: when the enthalpy of the feedwater at the outlet of the low-pressure heater is lower than the set enthalpy value of the unit feedwater, the third valve 2-3 can be opened to adjust the feedwater enthalpy value.

[0040] In some embodiments of the present invention, the control method of the flue gas pollutant treatment system coupled with flexible peak shaving of thermal power further includes: when the unit is ramping up, reducing the opening of the second valve 2-2 and the fourth valve 2-4, and increasing the opening of the first valve 2-1. The adjustment rate of the opening of the first valve 2-1 is determined according to the difference between the ramping output of other peak shaving measures of the generator unit and the required ramping capacity. At the same time, the opening of the third valve 2-3 is increased to ensure the stability of the enthalpy value of the feedwater at the outlet of the first low-pressure heater 25.

[0041] In other words, when other peak-shaving methods are insufficient to provide the required ramp-up rate for the generator set, the openings of the second valve 2-2 and the fourth valve 2-4 are reduced, while the opening of the first valve 2-1 is increased to increase the output of the low-pressure cylinder 21-2. The adjustment rate of the opening of the first valve 2-1 is determined based on the difference between the ramp-up output of other peak-shaving measures of the generator set and the required ramp-up capacity. Simultaneously, the opening of the third valve 2-3 is increased to ensure the stability of the enthalpy of the feedwater at the low-pressure heater outlet. Of course, since adjusting the air intake of the low-pressure cylinder 21-2 can quickly increase the output of the turbine 21, the high-temperature reheat steam from the steam-gas heat exchanger 322 can also be preferentially switched directly to the low-pressure cylinder 21-2 to quickly increase the output of the turbine 21, achieving a second-level response to unit load increases.

[0042] The advantages of the above method are as follows: switching the catalyst regeneration heat source to the steam-water system 2 can rapidly increase the load of the turbine 21 and meet the unit's rapid load increase response requirements; when the reheat steam of the steam-gas heat exchanger 322 is switched to the low-pressure cylinder 21-2, the regeneration tower 32 will be in a state without a regeneration heat source. Since the carbon-based catalytic multi-pollutant synergistic removal process has excellent pollutant removal stability, the pollutant treatment system 3 can still maintain the pollutant emission compliance capacity for several hours when the material circulation system is shut down. It can fully adsorb the flue gas pollutants in the case of no regeneration heat source during the unit's ramp-up phase, and the maintenance time is generally 6 to 8 hours.

[0043] In a specific example of the present invention, the increased peak-shaving capacity of the 300MW unit through the control method of the present invention is shown in the table below:

[0044] Therefore, the present invention can increase the peak load range of the unit by at least 10.08MW, improve the low load output and stable combustion capability of the unit's boiler system, and increase the peak load response of the unit by at least 3.36%Pe within the second time domain. At the same time, it can ensure that the unit meets the pollutant emission index requirements and improve the unit's peak load flexibility and economy.

[0045] The above embodiments omit the necessary conventional technical measures taken by thermal power units to ensure safe, stable, energy-saving and environmentally friendly production.

[0046] Other components and operations of the flue gas pollutant treatment system coupled with flexible peak shaving of thermal power plants according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0047] In the description of this specification, references to terms such as "some embodiments," "optionally," "furthermore," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0048] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A flue gas pollutant treatment system coupled with flexible peak shaving of thermal power plants, characterized in that, include: The flue gas system (1) includes a boiler (11); The steam system (2) is connected to the boiler (11), and the steam system (2) and the flue gas system (1) together form the thermal power main unit heat production system; A pollutant treatment system (3) is connected to the flue gas system (1) and is used to receive the flue gas generated by the flue gas system (1). The water vapor system (2) is adapted to provide a heat source for the catalyst in the pollutant treatment system (3). The steam-water system (2) includes a steam turbine (21), a reheater (22), a condenser, a low-pressure feedwater pump (24), a first low-pressure heater (25), a second low-pressure heater, a deaerator (27), a high-pressure feedwater pump (28), and a high-pressure heater (29). The steam turbine (21) includes a high-pressure cylinder (21-1) and a low-pressure cylinder (21-2). One path of the high-pressure cylinder (21-1) is connected to the high-pressure heater (29) through a regenerative steam extraction pipe. The regenerative steam extraction pipe is equipped with a sixth valve (2-6) for adjusting the extraction volume. The other path of the high-pressure cylinder (21-1) is connected to the reheater (22) through a pipe. The reheater (22) is connected to the steam-gas heat exchanger (322) of the pollutant treatment system (3) through a first pipe. The first branch pipe connects the first pipe and the low-pressure cylinder (21-2). The first branch pipe is equipped with a first valve (2-1) for adjusting the main steam flow. The low-pressure cylinder (21-2) is connected to the high-pressure cylinder (21-1). One path of the low-pressure cylinder (21-2) is connected to the first low-pressure heater (25) via the condenser and the low-pressure feedwater pump (24). The other path of the low-pressure cylinder (21-2) is connected to the second low-pressure heater via a regenerative steam extraction pipe. The regenerative steam extraction pipe is equipped with a fifth valve (2-5) for adjusting the extraction volume. The second low-pressure heater is connected downstream of the first low-pressure heater (25). The steam-gas exchanger... The heat exchanger (322) is connected to the first low-pressure heater (25) through a second pipeline. The first pipeline and the second pipeline are connected through a second branch pipe. The connection point between the first branch pipe and the first pipeline is located upstream of the connection point between the second branch pipe and the first pipeline. The second branch pipe is equipped with a third valve (2-3). The steam inlet of the steam-gas heat exchanger (322) is equipped with a second valve (2-2), and the steam outlet of the steam-gas heat exchanger (322) is equipped with a fourth valve (2-4). The steam outlet of the low-pressure heater is connected to the boiler (11) in sequence through the deaerator (27), the high-pressure feed water pump (28), and the high-pressure heater (29).

2. The flue gas pollutant treatment system coupled with flexible peak shaving of thermal power plants according to claim 1, characterized in that, The flue gas system (1) also includes a high-temperature denitrification device (12) and a dust collector (13). The boiler (11), the high-temperature denitrification device (12) and the dust collector (13) are connected in sequence through a flue. The flue gas generated by the boiler (11) is suitable to enter the pollutant treatment system (3) by passing through the high-temperature denitrification device (12) and the dust collector (13) in sequence.

3. The flue gas pollutant treatment system coupled with flexible peak shaving of thermal power plants according to claim 1, characterized in that, The pollutant treatment system (3) further includes: a purification tower (31), a regeneration tower (32), an ammonia injection device, and a vibrating screen (33). The flue gas generated by the flue gas system (1) enters the purification tower (31) after ammonia is injected by the ammonia injection device. The purification tower (31) contains a catalyst, which is suitable for adsorbing and removing SO2 in the flue gas. The NOx in the flue gas is suitable for being catalytically reduced by the catalyst. The catalyst that is saturated with adsorption is suitable for being transported to the regeneration tower (32) for thermal regeneration. After being cooled and screened by the vibrating screen (33), the portion of the catalyst with qualified particle size is suitable for being transported to the purification tower (31).

4. The flue gas pollutant treatment system coupled with flexible peak shaving of thermal power plants according to claim 3, characterized in that, The regeneration tower (32) includes a preparatory section (32-1), a heating section (32-2), a constant temperature section (32-3), and a cooling section (32-4). The preparatory section (32-1) is used for preheating the catalyst and controlling the material level. The heating section (32-2) is used to heat the catalyst so that the temperature meets the requirements for catalyst regeneration. The constant temperature section (32-3) serves as the catalyst regeneration site to ensure that the catalyst regeneration residence time meets the requirements. The cooling section (32-4) is used to cool the regenerated catalyst and meet the requirements for pollutant removal. The water vapor system (2) is adapted to provide a heat source for the heating section (32-2).

5. The flue gas pollutant treatment system coupled with flexible peak shaving of thermal power plants according to claim 4, characterized in that, The pollutant treatment system (3) also includes a steam-gas heat exchanger (322) and a high-temperature air fan (321). The heating section (32-2), the high-temperature air fan (321) and the steam-gas heat exchanger (322) are connected by a high-temperature air pipe to form a hot air circulation loop.

6. The flue gas pollutant treatment system coupled with flexible peak shaving of thermal power plants according to claim 4, characterized in that, The pollutant treatment system (3) also includes a sulfur resource recovery device (34), which is connected to the constant temperature section (32-3) and is used to recover SO2.

7. The flue gas pollutant treatment system coupled with flexible peak shaving of thermal power plants according to claim 1, characterized in that, The catalyst is a carbon-based catalyst, which includes activated coke or activated carbon.

8. A control method for a flue gas pollutant treatment system coupled with flexible peak shaving of thermal power plants as described in any one of claims 1-7, characterized in that, include: Obtain the unit's operating status; When the unit is running at low load, the opening of the first valve (2-1) is reduced, the opening of the second valve (2-2) and the fourth valve (2-4) is increased, the catalyst material circulation rate and / or catalyst regeneration temperature in the pollutant treatment system (3) are increased, the heat exchange load of the steam-gas heat exchanger (322) is increased, and the opening of the third valve (2-3) is adjusted so that the outlet feedwater enthalpy of the first low-pressure heater (25) remains stable.

9. The control method for the flue gas pollutant treatment system coupled with flexible peak shaving of thermal power plants according to claim 8, characterized in that, Also includes: When the unit is operating under normal conditions, the opening degrees of the first valve (2-1), the fifth valve (2-5), and the sixth valve (2-6) are controlled to meet the power output requirements of the generator set. The third valve (2-3) is closed, and the opening degrees of the second valve (2-2) and the fourth valve (2-4) are controlled to meet the heat exchange load requirements of the steam-gas heat exchanger (322). The heat exchange load is positively correlated with the concentration of SO2 in the flue gas and the regeneration set temperature, and satisfies the following conditions: Where: Q is the heat load of the steam-gas heat exchanger (322); c is the specific heat capacity of the catalyst; and These are the average temperatures of the catalyst at the inlet and outlet of the heating section (32-2), respectively. The heat of physical adsorption of SO2 in flue gas by the catalyst; The heat of decomposition of sulfuric acid generated from the chemical adsorption of SO2 in the catalyst; The heat dissipation of the heating section (32-2) and the constant temperature section (32-3) is as follows: when the enthalpy of the feedwater at the outlet of the low-pressure heater is lower than the set enthalpy value of the unit feedwater, the third valve (2-3) can be opened to adjust the feedwater enthalpy value.

10. The control method for the flue gas pollutant treatment system coupled with flexible peak shaving of thermal power plants according to claim 8, characterized in that, Also includes: When the unit is running on a ramp, the opening of the second valve (2-2) and the fourth valve (2-4) is reduced, and the opening of the first valve (2-1) is increased. The adjustment rate of the opening of the first valve (2-1) is determined based on the difference between the ramp output of other peak-shaving measures of the generator set and the required ramp capacity. At the same time, the opening of the third valve (2-3) is increased to ensure the stability of the enthalpy value of the feedwater at the outlet of the first low-pressure heater (25).

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