Coupling coal-fired unit peak regulation system for steam drum type staged combustion gas-fired boiler

Abstract

The invention relates to the technical field of heat storage peak regulation, in particular to a coupling coal-fired unit peak regulation system for a steam drum type staged combustion gas boiler. When the load of the coal-fired unit is reduced, the opening degree of a regulating valve of the steam turbine unit is reduced, the steam inlet amount of the steam turbine unit is reduced, the coal feeding amount of the coal-fired boiler part is gradually reduced, the output of a bypass water pump is increased, and high-pressure hot water in a boiler water loop is pumped into a boiler barrel through a one-way throttle valve so as to reduce the evaporation amount of a boiler of the coal-fired unit; when the load of the coal-fired unit is increased, the opening degree of a regulating valve of the steam turbine unit is gradually increased, the steam inlet amount of the steam turbine unit is increased, the coal feeding amount of the coal-fired boiler part is gradually increased, and the fuel part provides gas fuel for the gas-fired boiler part, so that the output of the gas-fired boiler part is increased; and saturated water circulating in the front-stage saturated heating section absorbs heat to generate superheated steam, and the superheated steam is introduced into the steam turbine unit to quickly supplement high-pressure steam required by load rising. Therefore, according to the technical scheme, the change of the load can be quickly responded.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal energy storage for peak shaving, and particularly to a peak shaving system for a steam drum type staged combustion gas boiler coupled with a coal-fired power unit. Background Art

[0002] The large-scale access of wind and solar renewable electricity is of great significance to the construction of a new power system. However, the volatility and randomness of wind and solar power generation pose a huge challenge to the power system. The rapid peak shaving of coal-fired power units is a key technology to ensure the stability of the power grid.

[0003] When a coal-fired power unit participates in peak shaving, its main operation mode is to adjust the load of the unit to match the power consumption of the power grid. The change of the unit load is generally achieved by adjusting the steam flow by changing the heat load of the furnace, and then adjusting the work done by the steam turbine. The change of the furnace heat load is mainly achieved by adjusting the coal grinding output to adjust the coal grinding amount and the coal feeding amount. However, adjusting the load by changing the coal feeding amount on the coal supply side has a large adjustment inertia, which requires a long time, resulting in a slow response speed to the load and making it difficult to adapt to the rapid change of wind and solar renewable power supply.

[0004] Therefore, there is an urgent need to provide a peak shaving system for a steam drum type staged combustion gas boiler coupled with a coal-fired power unit to solve the above technical problems. Summary of the Invention

[0005] In order to achieve a rapid response to the change of load, an embodiment of the present invention provides a peak shaving system for a steam drum type staged combustion gas boiler coupled with a coal-fired power unit.

[0006] An embodiment of the present invention provides a peak shaving system for a steam drum type staged combustion gas boiler coupled with a coal-fired power unit, including: A coal-fired boiler part, including a furnace, a boiler water circuit arranged around the furnace, and a feedwater heater group connected to the boiler water circuit. The feedwater heater group is used to heat and deoxygenate the feedwater before entering the boiler water circuit to generate saturated water, and the furnace and the boiler water circuit are used to heat the saturated water from the feedwater heater group to generate superheated steam; A gas boiler part, including a pre-stage saturated heating section, a post-stage superheating section, a first steam drum, a steam drum, and a tail flue. The pre-stage saturated heating section and the post-stage superheating section are both located in the steam drum. The steam drum is divided into the pre-stage saturated heating section and the post-stage superheating section by the first steam drum, and the pre-stage saturated heating section and the post-stage superheating section are respectively connected to the tail flue; The regulating part includes a bypass water pump, a one-way throttle valve, a steam-water separator, and a separation water pump. The boiler water circuit, the bypass water pump, the one-way throttle valve, and the front-stage saturated heating section are connected in sequence. The inlet end of the steam-water separator is connected to the rear-stage superheated heating section, and the outlet end is respectively connected to two separation gas paths and a separation water path. The separation water pump is arranged on the separation water path. One of the separation gas paths and the separation water path are respectively connected to the regenerative heater group; The power generation part includes a steam turbine unit and a generator connected in sequence. The inlet end of the steam turbine unit is connected to the boiler water circuit, and the other separation gas path is connected to the steam turbine unit; The fuel part is used to provide gaseous fuel to the gas boiler part.

[0007] An embodiment of the present invention provides a drum-type staged combustion gas boiler coupled with a coal-fired unit peak shaving system. When the coal-fired unit reduces load, the opening of the regulating valve of the steam turbine unit decreases, the pressure in front of the valve rises rapidly, the steam inlet volume of the steam turbine unit decreases, the feed water flow rate of the coal-fired boiler part gradually decreases, the coal feed rate of the coal-fired boiler part gradually decreases, the output of the bypass water pump is increased, and the high-pressure hot water in the boiler water circuit is pumped into the drum through the one-way throttle valve. The feed water flow rate of the gas boiler part increases. Most of the high-pressure hot water from the coal-fired unit reaches the saturated water state in the front-stage saturated heating section and circulates in the front-stage saturated heating section to reduce the evaporation volume of the boiler of the coal-fired unit; when the coal-fired unit increases load, the opening of the regulating valve of the steam turbine unit gradually increases, the pressure in front of the valve rapidly decreases, the steam inlet volume of the steam turbine unit increases, the feed water flow rate of the coal-fired boiler part gradually increases, the coal feed rate of the coal-fired boiler part gradually increases, the fuel part provides gaseous fuel to the gas boiler part to increase the output of the gas boiler part. The saturated water circulating in the front-stage saturated heating section absorbs heat to generate a steam-water mixture. After the steam-water mixture is separated by the first drum to generate saturated steam, the saturated steam continues to absorb heat in the rear-stage superheated heating section to generate superheated steam. After being separated by the steam-water separator, it is introduced into the steam turbine unit through the other separation gas path to quickly supplement the high-pressure steam required for load increase. Therefore, the above technical solution can achieve a rapid response to load changes. Description of the Drawings

[0008] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0009] Figure 1 It is a structural schematic diagram of a drum-type staged combustion gas boiler coupled with a coal-fired unit peak shaving system provided by an embodiment of the present invention.

[0010] Figure 2 It is a schematic structural diagram of a peak shaving system for a gas - fired boiler with segmented combustion in a steam drum coupled with a coal - fired power unit provided by another embodiment of the present invention; Figure 3 is Figure 1 a schematic structural diagram of the gas - fired boiler part in the peak shaving system shown.

[0011] Reference numerals: 1 - Coal - fired boiler part; 11 - Furnace; 12 - Regenerative heater group; 121 - #1 high - pressure heater; 122 - #2 high - pressure heater; 123 - #3 high - pressure heater; 124 - Deaerator; 2 - Gas - fired boiler part; 21 - Front - stage saturated heating section; 211 - Front - stage burner; 212 - Front - stage furnace drum; 213 - Front - stage smoke tube; 22 - Rear - stage superheat heating section; 221 - Rear - stage burner; 222 - Rear - stage furnace drum; 223 - Rear - stage smoke tube; 23 - First steam drum; 24 - Boiler drum; 25 - Tail flue; 3 - Regulation part; 31 - Bypass water pump; 32 - One - way throttle valve; 33 - Steam - water separator; 34 - Separation water pump; 35 - Flow regulating valve; 4 - Power generation part; 41 - Steam turbine unit; 42 - Generator; 5 - Fuel part; 51 - Gas fuel storage tank; 52 - Gas fuel inlet pipeline; 53 - Cracking furnace; 54 - Pressure regulator; 55 - Three - way valve; 6 - Control part; 61 - Control circuit. Detailed implementation manners

[0012] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0013] As Figure 1 and Figure 2 shown, an embodiment of the present invention provides a peak shaving system for a drum-type staged combustion gas boiler coupled with a coal-fired power unit. The system includes a coal-fired boiler part 1, a gas boiler part 2, a regulating part 3, a power generation part 4, and a fuel part 5, where: The coal-fired boiler part 1 includes a furnace 11, a water circuit around the furnace 11, and a regenerative heater group 12 connected to the water circuit. The regenerative heater group 12 is used to heat and deoxygenate the feed water before it enters the water circuit to produce saturated water. The furnace 11 and the water circuit are used to heat the saturated water from the regenerative heater group 12 to produce superheated steam. The gas boiler part 2 includes a pre-stage saturated heating section 21, a post-stage superheating section 22, a first steam drum 23, a boiler drum 24, and a tail flue 25. Both the pre-stage saturated heating section 21 and the post-stage superheating section 22 are located inside the boiler drum 24. The boiler drum 24 is divided into the pre-stage saturated heating section 21 and the post-stage superheating section 22 by the first steam drum 23. The pre-stage saturated heating section 21 and the post-stage superheating section 22 are respectively connected to the tail flue 25. The regulating part 3 includes a bypass water pump 31, a one-way throttle valve 32, a steam-water separator 33, and a separation water pump 34. The water circuit, the bypass water pump 31, the one-way throttle valve 32, and the pre-stage saturated heating section 21 are connected in sequence. The inlet end of the steam-water separator 33 is connected to the post-stage superheating section 22, and the outlet end is respectively connected to two separation gas paths and one separation water path. The separation water pump 34 is arranged on the separation water path. One of the separation gas paths and the separation water path are respectively connected to the regenerative heater group 12. The power generation part 4 includes a steam turbine unit 41 and a generator 42 connected in sequence. The inlet end of the steam turbine unit 41 is connected to the water circuit, and the other separation gas path is connected to the steam turbine unit 41. The fuel part 5 is used to supply gaseous fuel to the gas boiler part 2.

[0014] In this embodiment, when the coal-fired unit reduces its load, the opening of the regulating valve of the steam turbine unit 41 decreases, the pressure before the valve rapidly increases, the steam intake of the steam turbine unit 41 decreases, the feed water flow rate of the coal-fired boiler part 1 gradually decreases, the coal feeding amount of the coal-fired boiler part 1 gradually decreases, the output of the bypass water pump 31 is increased, and the high-pressure hot water in the boiler water circuit is pumped into the drum 24 through the one-way throttle valve 32. The feed water flow rate of the gas boiler part 2 increases. Most of the high-pressure hot water from the coal-fired unit reaches the saturated water state in the pre-stage saturated heating section 21 and circulates in the pre-stage saturated heating section 21 to reduce the evaporation capacity of the boiler of the coal-fired unit. When the coal-fired unit increases its load, the opening of the regulating valve of the steam turbine unit 41 gradually increases, the pressure before the valve rapidly decreases, the steam intake of the steam turbine unit 41 increases, the feed water flow rate of the coal-fired boiler part 1 gradually increases, the coal feeding amount of the coal-fired boiler part 1 gradually increases, and the fuel part 5 supplies gaseous fuel to the gas boiler part 2 to increase the output of the gas boiler part 2. The saturated water circulating in the pre-stage saturated heating section 21 absorbs heat to generate a steam-water mixture. After the steam-water mixture is separated by the first steam drum 23 to produce saturated steam, the saturated steam continues to absorb heat in the post-stage superheat heating section 22 to generate superheated steam. After being separated by the steam-water separator 33, it is introduced into the steam turbine unit 41 through another separation gas path to quickly supplement the high-pressure steam required for load increase. Therefore, the above technical solution can achieve a rapid response to load changes.

[0015] It should be noted that by setting the steam-water separator 33, not only can the separated steam be sent to the steam turbine unit 41 for work, but also it can prevent the steam turbine unit 41 from being eroded by water to ensure the safe and stable operation of the steam turbine unit 41. Moreover, the separated steam can be circulated back to the regenerative heater group 12 of the coal-fired boiler through the separation water path after the separation water pump 34, thus saving water consumption.

[0016] In an embodiment of the present invention, the regenerative heater group 12 includes a #1 high-pressure heater 121, a #2 high-pressure heater 122, a #3 high-pressure heater 123, and a deaerator 124. The pre-stage saturated heating section 21 includes a pre-stage burner 211, a pre-stage furnace drum 212, and a pre-stage smoke tube 213 connected in sequence. The post-stage superheat heating section 22 includes a post-stage burner 221, a post-stage furnace drum 222, and a post-stage smoke tube 223 connected in sequence. The pre-stage smoke tube 213, the post-stage smoke tube 223, and the tail flue 25 are connected in sequence.

[0017] In this embodiment, when the coal-fired unit reduces its load, the feed water flow rate of the gas boiler section 2 increases. The duty nozzles in the front-stage burner 211 of the gas boiler maintain a low-power duty flame state. Most of the high-pressure hot water from the coal-fired unit reaches the saturated water state after heat exchange with the front-stage flue gas pipe 213 in the front-stage saturation heating section 21 and circulates in the front-stage saturation heating section 21 to reduce the evaporation capacity of the boiler of the coal-fired unit. A small portion of the steam is separated by the first steam drum 23 and enters the rear-stage superheat heating section 22 to exchange heat with the rear-stage flue gas pipe 223 to generate superheated steam. After being separated by the steam-water separator 33, the superheated steam enters the #1 high-pressure heater 121, #2 high-pressure heater 122, and #3 high-pressure heater 123 through the separation gas path II to heat the feed water, and the saturated water returns to the deaerator 124 to supplement the feed water of the coal-fired unit boiler. When the coal-fired unit increases its load, the gaseous fuel is distributed to the front-stage burner 211 and the rear-stage burner 221. The front-stage burner 211 and the rear-stage burner 221 change from the low-power duty flame state to the high-power stable combustion state. The output of the gas boiler section 2 increases. The flue gas temperature in the front-stage flue gas pipe 213 and the rear-stage flue gas pipe 223 rises, and the flow rate accelerates. The saturated water circulating in the front-stage saturation heating section 21 exchanges heat with the front-stage flue gas pipe 213 to generate a steam-water mixture. After the steam-water mixture is separated by the first steam drum 23 to produce saturated steam, the saturated steam continues to exchange heat with the rear-stage flue gas pipe 223 in the rear-stage superheat heating section 22 to generate superheated steam. After being separated by the steam-water separator 33, it is introduced into the steam turbine unit 41 to quickly supplement the high-pressure steam required for load increase. After the flue gas generated by the combustion of the gas boiler exchanges heat with the water and steam in the water-wall drum 24 in the front-stage flue gas pipe 213 in the front-stage saturation heating section 21 and the rear-stage flue gas pipe 223 in the rear-stage superheat heating section 22, it is discharged into the tail flue of the coal-fired boiler through the tail flue 25 to heat the economizer and air preheater of the coal-fired boiler.

[0018] In an embodiment of the present invention, the fuel section 5 includes a gaseous fuel storage tank 51, a gaseous fuel inlet pipe 52, a pressure regulator 54, and a three-way valve 55 connected in sequence. The gaseous fuel storage tank 51 is used to store gaseous fuel. The three-way valve 55 is respectively connected to the front-stage burner 211 and the rear-stage burner 221 and is used to adjust the flow rate of the gaseous fuel entering the front-stage burner 211 and the rear-stage burner 221.

[0019] In this embodiment, when the coal-fired unit increases its load, the gas boiler acts quickly, and the pressure regulator 54 automatically adjusts to increase the gaseous fuel flow rate. The gaseous fuel is distributed to the front-stage burner 211 and the rear-stage burner 221 through the flow rate of the gaseous fuel inlet pipe 52 and the three-way valve 55.

[0020] In an embodiment of the present invention, the gaseous fuel is natural gas, hydrogen, ammonia, coke oven gas or blast furnace gas. When the gaseous fuel is ammonia, the fuel part 5 further includes a cracking furnace 53 connected to the outlet end of the gaseous fuel inlet pipe 52.

[0021] In an embodiment of the present invention, it further includes a control part 6. The control part 6 is electrically connected to the pre-stage burner 211, the post-stage burner 221, the bypass water pump 31, the steam turbine unit 41 and the generator 42 through control lines 61 respectively. The control part 6 is used to control the heating amount of the pre-stage burner 211 and the post-stage burner 221 and the output of the bypass water pump 31 according to the detected flow rate, temperature, pressure of the steam and water of the steam turbine unit 41 and the power of the generator 42, so as to achieve a rapid response to the change of the load of the coal-fired unit.

[0022] In an embodiment of the present invention, when the coal-fired unit reduces its load, the opening of the regulating valve of the steam turbine unit 41 decreases, the pressure before the valve rises rapidly, the steam inlet volume of the steam turbine unit 41 decreases, the feed water flow rate of the coal-fired boiler part 1 gradually decreases, and the coal feeding amount of the coal-fired boiler part 1 gradually decreases. The control part 6 receives the load reduction signals of the steam turbine unit 41 and the generator 42, and sends a signal to the bypass water pump 31 to increase the output of the bypass water pump 31, and pumps the high-pressure hot water in the boiler water circuit into the drum 24 through the one-way throttle valve 32. The feed water flow rate of the gas boiler part 2 increases. The duty nozzle in the pre-stage burner 211 maintains a small-power duty flame state. Most of the high-pressure hot water from the coal-fired unit reaches the saturated water state after heat exchange with the pre-stage smoke pipe 213 in the pre-stage saturation heating section 21 and circulates in the pre-stage saturation heating section 21 to reduce the evaporation amount of the boiler of the coal-fired unit. A small part of the steam enters the post-stage superheat heating section 22 after being separated by the first steam drum 23 and exchanges heat with the post-stage smoke pipe 223 to generate superheated steam. After being separated by the steam-water separator 33, the superheated steam enters the regenerative heater group 12 through one of the separation gas paths to heat the feed water; When the coal-fired unit increases its load, the opening of the regulating valve of the steam turbine unit 41 gradually increases, the pressure in front of the valve rapidly decreases, the steam inlet volume of the steam turbine unit 41 increases, the feed water flow of the coal-fired boiler part 1 gradually increases, and the coal feeding volume of the coal-fired boiler part 1 gradually increases. The control part 6 receives the load increase signals of the steam turbine unit 41 and the generator 42, and sends a signal to the gas boiler part 2. The pressure regulator 54 automatically adjusts to increase the gas fuel flow. The gas fuel enters the front-stage burner 211 and the rear-stage burner 221 respectively after passing through the gas fuel inlet pipe 52 and the three-way valve 55. The front-stage main nozzle in the front-stage burner 211 passes through the fuel and starts to burn. Then, the rear-stage first-stage nozzle, the rear-stage second-stage nozzle, the rear-stage third-stage nozzle, and the rear-stage fourth-stage nozzle of the rear-stage burner 221 are sequentially opened for combustion heating to increase the temperature of the working medium in the rear-stage furnace drum. The output of the gas boiler part 2 increases, the flue gas temperature in the front-stage flue pipe 213 and the rear-stage flue pipe 223 increases, and the flow rate accelerates. The saturated water circulating in the front-stage saturated heating section 21 exchanges heat with the front-stage flue pipe 213 to generate a steam-water mixture. The steam-water mixture is separated by the first steam drum 23 to generate saturated steam. The saturated steam continues to exchange heat with the rear-stage flue pipe 223 in the rear-stage superheating section 22 to generate superheated steam. After being separated by the steam-water separator 33, it is introduced into the steam turbine unit 41 through another separation gas path to quickly supplement the high-pressure steam required for load increase. The flue gas generated by the combustion of the gas boiler exchanges heat with the water and steam in the boiler drum 24 in the front-stage flue pipe 213 and the rear-stage flue pipe 223, and then is discharged into the tail flue of the coal-fired boiler through the tail flue 25.

[0023] In an embodiment of the present invention, when the load of the coal-fired unit is stable, the duty nozzle in the front-stage burner 211 maintains a low-power duty flame state. The high-temperature flue gas generated by the combustion in the front-stage burner 211 first enters the front-stage flue pipe 213 through the front-stage furnace drum 212. The high-temperature flue gas impacts the inner wall of the flue pipe in the front-stage flue pipe 213 and convectively exchanges heat with the high-pressure hot water in the front-stage saturated heating section 21 to make the high-pressure hot water reach the saturated water state and circulate in the front-stage saturated heating section 21.

[0024] In an embodiment of the present invention, the front-stage burner 211 is provided with a duty nozzle arranged in a central surrounding manner and a front-stage main nozzle arranged in a surrounding manner around the periphery. The rear-stage burner 221 is axially provided with a rear-stage first-stage nozzle, a rear-stage second-stage nozzle, a rear-stage third-stage nozzle, and a rear-stage fourth-stage nozzle arranged in a surrounding manner in sequence. The distance between the rear-stage first-stage nozzle and the rear-stage second-stage nozzle is H1, the distance between the rear-stage second-stage nozzle and the rear-stage third-stage nozzle is H2, and the distance between the rear-stage third-stage nozzle and the rear-stage fourth-stage nozzle is H3, and H1 < H2 < H3.

[0025] In this embodiment, considering that when the coal-fired unit increases its load, the saturated water in the pre-stage saturated heating section 21 needs to be converted into superheated steam and supplied to the coal-fired boiler section 1. During the process of converting saturated water into superheated steam, the saturated water first needs to be heated to become a steam-water mixture, and then the steam-water mixture needs to be heated to become superheated steam. During this process, the inventor found that: the heating amount required for converting saturated water into a steam-water mixture is greater than the heating amount for converting the steam-water mixture into superheated steam. Therefore, the rear-stage nozzles can be designed to be multi-stage (for example, four-stage), and along the steam supply direction, the spacing between the rear-stage nozzles gradually increases, that is, H1 < H2 < H3. In this way, the effective utilization of energy can be ensured.

[0026] In an embodiment of the present invention, when the furnace 11 is a drum boiler, the furnace water circuit includes a second drum, a downcomer, a lower header, a water wall, and an upper header that are connected end to end in sequence. A furnace water circulation pump is provided in the downcomer. The second drum is connected to the superheater in front of the steam turbine unit 41, and the pre-stage saturated heating section 21 is connected to the outlet end of the downcomer; When the furnace 11 is a once-through boiler, the furnace water circuit includes an evaporator tube, a start-up separator, and a furnace water circulation pump that are connected end to end in sequence. A economizer is provided on the evaporator tube. The start-up separator is connected to the superheater, and the pre-stage saturated heating section 21 is connected to the outlet end of the economizer. By setting it in this way, the evaporation water volume in the furnace water circuit can be reduced.

[0027] In this embodiment, for a drum boiler, by setting the pre-stage saturated heating section 21, high-pressure hot water from the downcomer can be stored. For a once-through boiler, high-pressure hot water from the economizer can be stored.

[0028] In addition, by setting the bypass water pump 31, for a drum boiler, on the one hand, it can heat the high-pressure hot water from the downcomer to generate saturated water, and on the other hand, it can play a role in providing power, that is, send the high-pressure hot water in the downcomer to the pre-stage saturated heating section 21 for storage. For a once-through boiler, on the one hand, it can heat the high-pressure hot water from the economizer to generate saturated water, and on the other hand, it can play a role in providing power, that is, send the high-pressure hot water in the economizer to the pre-stage saturated heating section 21 for storage.

[0029] It should be noted that precisely because the separation water pump 34 is provided, the hot water in the separated water path after being separated by the steam-water separator 33 can be sent to the deaerator 124 of the coal-fired unit. After being heated and deaerated by the deaerator 124 of the coal-fired unit and heated by the #1 high-pressure heater 121, #2 high-pressure heater 122, and #3 high-pressure heater 123, saturated water is generated and sent to the furnace water circuit.

[0030] In an embodiment of the present invention, for a drum boiler, the outlet end of the downcomer is connected to the bypass water pump 31, and the hot water pressure in the pre-stage saturated heating section 21 is greater than the hot water pressure in the downcomer; For a once-through boiler, the outlet end of the economizer is connected to the bypass water pump 31, and the hot water pressure in the front-stage saturation heating section 21 is greater than the hot water pressure in the economizer.

[0031] In an embodiment of the present invention, a separation gas path connected to the steam turbine unit 41 includes two first gas paths and a second gas path connected in parallel with each other. A one-way throttle valve 32, a flow regulating valve 35, and a one-way throttle valve 32 are sequentially arranged on the first gas path, and a one-way throttle valve 32 is arranged on the second gas path. The opening and closing of the first gas path and the second gas path are controlled by the load of the coal-fired boiler section 1; When the coal-fired boiler section 1 rapidly increases the load, the steam separated by the steam separator 33 enters the steam turbine unit 41 through the second gas path. When the load of the coal-fired boiler section 1 slowly changes, the steam separated by the steam separator 33 enters the steam turbine unit 41 through the first gas path.

[0032] In this embodiment, considering that the evaporation amount decreases when the coal-fired unit reduces the load and hot water in the boiler water circuit needs to be stored; when the coal-fired unit increases the load, a large amount of high-pressure steam needs to be provided quickly. Therefore, a gas-fired boiler section 2 can be arranged after the bypass water pump 31 to heat the hot water from the boiler water circuit to generate steam with required parameters and then enter the steam turbine unit 41. For example, if the steam temperature entering the high-pressure cylinder needs to be higher, the gas-fired boiler section 2 can be used to heat part of the hot water from the boiler water circuit. And for the steam temperatures entering the intermediate-pressure cylinder and the low-pressure cylinder, they may not need to be too high, so the output of the gas-fired boiler section 2 can be adjusted timely, which will not be elaborated here.

[0033] Refer to Figure 1 , to heat the hot water from the boiler water circuit, it includes a front-stage saturation heating section 21, a rear-stage superheating heating section 22, a steam drum 23, a boiler drum 24, and a tail flue 25. The front-stage saturation heating section 21 and the rear-stage superheating heating section 22 are both located in the boiler drum 24. The boiler drum 24 is divided into the front-stage saturation heating section 21 and the rear-stage superheating heating section 22 by the steam drum 23. The front-stage saturation heating section 21 includes a front-stage burner 211, a front-stage furnace drum 212, and a front-stage smoke tube 213 connected in sequence. The rear-stage superheating heating section 22 includes a rear-stage burner 221, a rear-stage furnace drum 222, and a rear-stage smoke tube 223 connected in sequence. The front-stage smoke tube 213, the rear-stage smoke tube 223, and the tail flue 25 are connected in sequence; the fuel section 5 is composed of a gas fuel storage tank 51, a gas fuel inlet pipeline 52, and a cracking furnace 53 connected in sequence. The gas fuel in the gas fuel storage tank 51 can be gas fuels such as natural gas, hydrogen, ammonia, coke oven gas, and blast furnace gas.

[0034] When the gaseous fuel is hydrogen, the gaseous fuel storage tank 51 can be arranged within the power plant area where the coal-fired unit is located. That is, an electrolytic hydrogen production device is arranged within the power plant area, and the electrolytic hydrogen production device is powered by the surplus electricity of wind-solar renewable power generation, plant electricity, or electricity generated by other means, so as to avoid the cost increase and safety risks caused by long-distance transportation of hydrogen.

[0035] In an embodiment of the present invention, referring to Figure 1 , a cracking furnace 53 is provided after the gaseous fuel inlet pipe 52. When the gaseous fuel is ammonia, ammonia enters the cracking furnace 53 through the gaseous fuel inlet pipe 52, and undergoes a chemical reaction in the cracking furnace 53 to crack into combustible gases such as hydrogen. These combustible gases and air enter the combustion chamber and burn inside. The setting of the cracking furnace 53 improves the fuel adaptability of the burner and also improves the fuel utilization rate.

[0036] In an embodiment of the present invention, the gaseous fuel enters the pre-stage burner 211 and the post-stage burner 221 through the gaseous fuel inlet pipe 52. The pre-stage burner 211 and the post-stage burner 221 operate at a low power in a duty flame state during the stable load operation of the coal-fired unit, burning a small amount of gaseous fuel to maintain stable operation, so as to reduce the use of gaseous fuel and reduce the ignition consumption time during the high-load operation of the gas boiler.

[0037] In an embodiment of the present invention, referring to Figure 2 , only a single burner 211 and a furnace drum 212 are provided in the gas boiler part 2, and the burner 211 operates at a low power in a duty flame state during the stable load operation of the coal-fired unit.

[0038] In some embodiments, the pre-stage smoke pipe 213 and the post-stage smoke pipe 223 are arranged in a multi-group serpentine layout or a multi-group staggered layout to increase the convective heat transfer between the hot water in the drum 24 and the smoke pipes, and improve the fuel utilization rate of the pre-stage burner 211 and the post-stage burner 221.

[0039] In summary, the thermal energy storage technology is one of the important development directions in the energy storage technology. The large-capacity thermal energy storage participating in the peak shaving of the power system can improve the cross-time and space optimization allocation ability of the energy system. As a flexible and controllable load, it can improve the regulation ability of the power system. When adjusting the load by changing the steam quantity on the steam supply side, the change in the steam quantity can adopt the form of thermal energy storage. When reducing the load, the high-pressure hot water in the furnace or the superheated steam at the outlet of the superheater is stored, so as to achieve the purpose of reducing the total steam quantity for load adjustment; when increasing the load, the stored high-pressure hot water or superheated steam is sent back to the steam circuit to supplement the total steam quantity; at the same time, adopting the form of thermal energy storage can make the total energy reach a smaller dissipation during the load change process.

[0040] It should be noted that in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A peak shaving system for a gas - fired boiler with a steam drum and staged combustion coupled with a coal - fired power unit, characterized in that, Comprising: A coal-fired boiler section (1), including a furnace (11), a boiler water circuit arranged around the furnace (11), and a feedwater heater group (12) connected to the boiler water circuit. The feedwater heater group (12) is used to heat and deoxygenate the feedwater before it enters the boiler water circuit to produce saturated water, and the furnace (11) and the boiler water circuit are used to heat the saturated water from the feedwater heater group (12) to produce superheated steam; A gas-fired boiler section (2), including a pre-stage saturated heating section (21), a post-stage superheating section (22), a first steam drum (23), a steam boiler drum (24), and a tail flue (25). Both the pre-stage saturated heating section (21) and the post-stage superheating section (22) are located within the steam boiler drum (24). The steam boiler drum (24) is divided into the pre-stage saturated heating section (21) and the post-stage superheating section (22) by the first steam drum (23). The pre-stage saturated heating section (21) and the post-stage superheating section (22) are respectively connected to the tail flue (25); A regulating section (3), including a bypass water pump (31), a one-way throttle valve (32), a steam-water separator (33), and a separation water pump (34). The boiler water circuit, the bypass water pump (31), the one-way throttle valve (32), and the pre-stage saturated heating section (21) are connected in sequence. The inlet end of the steam-water separator (33) is connected to the post-stage superheating section (22), and the outlet end is respectively connected to two separation gas paths and a separation water path. The separation water pump (34) is arranged on the separation water path. One of the separation gas paths and the separation water path are respectively connected to the feedwater heater group (12); A power generation section (4), including a steam turbine unit (41) and a generator (42) connected in sequence. The inlet end of the steam turbine unit (41) is connected to the boiler water circuit, and the other separation gas path is connected to the steam turbine unit (41); A fuel section (5), used to supply gaseous fuel to the gas-fired boiler section (2).

2. The peak shaving system for a drum - type staged - combustion gas - fired boiler coupled with a coal - fired unit according to claim 1, wherein The pre-stage saturated heating section (21) includes a pre-stage burner (211), a pre-stage furnace drum (212), and a pre-stage smoke tube (213) connected in sequence. The post-stage superheating section (22) includes a post-stage burner (221), a post-stage furnace drum (222), and a post-stage smoke tube (223) connected in sequence. The pre-stage smoke tube (213), the post-stage smoke tube (223), and the tail flue (25) are connected in sequence.

3. The peak shaving system for a gas - fired boiler with drum - type staged combustion coupled with a coal - fired unit according to claim 2, characterized in that, The fuel section (5) includes a gaseous fuel storage tank (51), a gaseous fuel inlet pipeline (52), a pressure regulator (54), and a three-way valve (55) connected in sequence. The gaseous fuel storage tank (51) is used to store gaseous fuel. The three-way valve (55) is respectively connected to the pre-stage burner (211) and the post-stage burner (221), and is used to adjust the flow rate of the gaseous fuel entering the pre-stage burner (211) and the post-stage burner (221).

4. The peak shaving system for a drum - type staged - combustion gas - fired boiler coupled with a coal - fired unit according to claim 3, wherein The gaseous fuel is natural gas, hydrogen, ammonia, coke oven gas or blast furnace gas. When the gaseous fuel is ammonia, the fuel section (5) further includes a cracking furnace (53) connected to the outlet end of the gaseous fuel inlet pipe (52).

5. The peak shaving system for a drum - type staged - combustion gas - fired boiler coupled with a coal - fired unit according to claim 3, wherein, It further includes a control section (6), and the control section (6) is electrically connected to the pre-stage burner (211), the post-stage burner (221), the bypass water pump (31), the steam turbine unit (41) and the generator (42) respectively through control lines (61).

6. The peak shaving system for a drum-type staged combustion gas boiler coupled with a coal-fired unit according to claim 5, characterized in that When the coal-fired unit reduces its load, the opening of the regulating valve of the steam turbine unit (41) decreases, the pressure in front of the valve rapidly increases, the steam inlet volume of the steam turbine unit (41) decreases, the feed water flow rate of the coal-fired boiler section (1) gradually decreases, the coal feeding volume of the coal-fired boiler section (1) gradually decreases. The control section (6) receives the load reduction signals of the steam turbine unit (41) and the generator (42), and sends a signal to the bypass water pump (31) to increase the output of the bypass water pump (31), and pumps the high-pressure hot water in the boiler water circuit into the drum (24) through the one-way throttle valve (32). The feed water flow rate of the gas boiler section (2) increases, the duty nozzle in the pre-stage burner (211) maintains a low-power duty flame state. The high-pressure hot water from the coal-fired unit exchanges heat with the pre-stage smoke pipe (213) in the pre-stage saturated heating section (21) and most of it reaches the saturated water state, and circulates in the pre-stage saturated heating section (21) to reduce the evaporation volume of the boiler of the coal-fired unit. A small part of the steam is separated by the first steam drum (23) and then enters the post-stage superheating heating section (22) to exchange heat with the post-stage smoke pipe (223) to generate superheated steam. After being separated by the steam-water separator (33), the superheated steam enters one of the separation gas paths into the regenerative heater group (12) to heat the feed water; When the coal-fired unit increases its load, the opening of the regulating valve of the steam turbine unit (41) gradually increases, the pressure in front of the valve rapidly decreases, the steam inlet volume of the steam turbine unit (41) increases, the feed water flow rate of the coal-fired boiler section (1) gradually increases, the coal feed rate of the coal-fired boiler section (1) gradually increases, the control section (6) receives the load increase signals of the steam turbine unit (41) and the generator (42), and sends a signal to the gas boiler section (2), and the pressure regulator (54) automatically adjusts to increase the gas fuel flow rate. The gas fuel enters the front-stage burner (211) and the rear-stage burner (221) respectively after passing through the gas fuel inlet pipe (52) and the three-way valve (55). Fuel is introduced into the front-stage main nozzle in the front-stage burner (211) and starts to burn; and the rear-stage first-stage nozzle, rear-stage second-stage nozzle, rear-stage third-stage nozzle, and rear-stage fourth-stage nozzle of the rear-stage burner (221) are sequentially opened for combustion heating to raise the temperature of the working medium in the rear-stage furnace drum; the output of the gas boiler section (2) increases, the flue gas temperature in the front-stage flue pipe (213) and the rear-stage flue pipe (223) increases, and the flow rate accelerates. The saturated water circulating in the front-stage saturated heating section (21) exchanges heat with the front-stage flue pipe (213) to generate a steam-water mixture. After the steam-water mixture is separated by the first steam drum (23), saturated steam is generated. The saturated steam continues to exchange heat with the rear-stage flue pipe (223) in the rear-stage superheat heating section (22) to generate superheated steam. After being separated by the steam-water separator (33), it is introduced into the steam turbine unit (41) through another separation gas path to quickly supplement the high-pressure steam required for load increase. The flue gas generated by the combustion of the gas boiler exchanges heat with the water and steam in the boiler drum (24) in the front-stage flue pipe (213) and the rear-stage flue pipe (223), and then is discharged into the tail flue of the coal-fired boiler through the tail flue (25); When the load of the coal-fired unit is stable, the duty nozzle of the front-stage burner (211) maintains a small-power duty flame state. The high-temperature flue gas generated by the combustion in the front-stage burner (211) first enters the front-stage flue pipe (213) through the front-stage furnace drum (212). The high-temperature flue gas impacts the inner wall of the flue pipe in the front-stage flue pipe (213) and convectively exchanges heat with the high-pressure hot water in the front-stage saturated heating section (21) to make the high-pressure hot water reach the saturated water state and circulate in the front-stage saturated heating section (21).

7. The peak shaving system for a drum - type staged - combustion gas - fired boiler coupled with a coal - fired unit according to claim 5, wherein, The front-stage burner (211) is provided with a duty nozzle arranged in a central surrounding manner and a front-stage main nozzle arranged in a surrounding manner on the periphery. The rear-stage burner (221) is axially provided with a rear-stage first-stage nozzle, a rear-stage second-stage nozzle, a rear-stage third-stage nozzle, and a rear-stage fourth-stage nozzle arranged in a surrounding manner in sequence. The distance between the rear-stage first-stage nozzle and the rear-stage second-stage nozzle is H1, the distance between the rear-stage second-stage nozzle and the rear-stage third-stage nozzle is H2, and the distance between the rear-stage third-stage nozzle and the rear-stage fourth-stage nozzle is H3, and H1 < H2 < H3.

8. The peak shaving system for a drum - type staged - combustion gas - fired boiler coupled with a coal - fired unit according to claim 1, characterized in that, When the furnace (11) is a drum boiler, the boiler water circuit includes a second steam drum, a downcomer, a lower header, a water wall and an upper header that are connected end to end in sequence. The downcomer is provided with a boiler water circulation pump. The second steam drum is connected to the superheater in front of the steam turbine unit (41). The pre-stage saturated heating section (21) is connected to the outlet end of the downcomer; When the furnace (11) is a once-through boiler, the boiler water circuit includes an evaporator tube, a start-up separator and a boiler water circulation pump that are connected end to end in sequence. A economizer is arranged on the evaporator tube. The start-up separator is connected to the superheater. The pre-stage saturated heating section (21) is connected to the outlet end of the economizer.

9. The peak shaving system for a coupled coal-fired unit of a steam drum type staged combustion gas boiler according to claim 8, characterized in that, For a drum boiler, the outlet end of the downcomer is connected to the bypass water pump (31), and the hot water pressure in the pre-stage saturated heating section (21) is greater than the hot water pressure in the downcomer; For a once-through boiler, the outlet end of the economizer is connected to the bypass water pump (31), and the hot water pressure in the pre-stage saturated heating section (21) is greater than the hot water pressure in the economizer.

10. The peak shaving system for a drum - type staged - combustion gas - fired boiler coupled with a coal - fired unit according to any one of claims 1 - 9, characterized in that, A separation gas path connected to the steam turbine unit (41) includes two first gas paths and a second gas path that are connected in parallel with each other. A one-way throttle valve (32), a flow regulating valve (35) and a one-way throttle valve (32) are arranged in sequence on the first gas path. A one-way throttle valve (32) is arranged on the second gas path. The opening and closing of the first gas path and the second gas path are controlled by the load of the coal-fired boiler part (1); When the coal-fired boiler part (1) rapidly increases the load, the steam separated by the steam-water separator (33) enters the steam turbine unit (41) through the second gas path. When the load of the coal-fired boiler part (1) changes slowly, the steam separated by the steam-water separator (33) enters the steam turbine unit (41) through the first gas path.

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