Thermal power generating unit and heating system thereof
By designing a heating system that includes spray tower, heating components and heating in the thermal power unit, the problem of ammonia escape and thermal heating thermal source in existing technologies has been solved, and the energy saving effect of the unit and the reduction of coal consumption is achieved. Effect.
Patent Information
- Application Number
- CN202411389846.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-08
- Publication Date
- 2025-01-24
AI Technical Summary
When using SCR denitrification technology in the existing thermal power units, due to catalyst failure and uneven mixing of flow fields, ammonia escape increases, resulting in corrosion and ash blockage of the boiler tail heated surface. At the same time, the heat source of the air heater is taken from high-grade low-addition Auxiliary steam extraction increases the unit's coal consumption.
A thermal power unit heating system is designed, including an air preheater, a spray tower, a heating component, a first heater and a second heater. This system cools down the concentrated solution in the spray tower through contact with the flue gas, producing a dilute solution which enters the heating component for heating, generating water vapor and hot solution. The hot solution and water vapor are used to heat the air flow of the first and second air heaters respectively. After further heating, they enter the air preheater and increase the inlet air temperature of the air preheater.
The system can save high -quality auxiliary steam, improve the energy saving effect of thermal power sets, reduce coal consumption, and prevent the cold end corrosion of the air preheat.
Smart Images
Figure CN119353689A_ABST
Abstract
Description
Technical Field
[0001] The embodiments of the present disclosure belong to the technical field of thermal power units, and specifically relate to a thermal power unit and a heating system thereof. Background Art
[0002] In the context of ultra-low emissions, thermal power units use SCR (Selective Catalytic Reduction) denitrification technology to control NOx emissions. Under the action of a catalyst, the injected ammonia is used to reduce NOx in the flue gas to N2. However, due to the failure of the catalyst and uneven mixing of the flow field, ammonia escape increases, causing corrosion and ash blockage on the subsequent heating surface.
[0003] In order to prevent low-temperature corrosion and ash blockage on the heating surface at the rear of the boiler, many power plants install air heaters at the fan outlet to increase the cold end wall temperature of the equipment by increasing the air temperature at the inlet of the air preheater, thereby alleviating the cold end corrosion of the air preheater and the blockage of ammonium bisulfate. However, the heat source of the air heater in the relevant technology is taken from the auxiliary extraction steam of the low-pressure heater with a higher extraction quality. Due to the high extraction quality, the coal consumption of the unit increases, resulting in a certain waste of resources. Summary of the invention
[0004] The embodiments of the present disclosure aim to solve at least one of the technical problems existing in the prior art and provide a thermal power unit and a heating system thereof.
[0005] On the one hand, an embodiment of the present disclosure provides a heating system for a thermal power unit, the heating system comprising an air preheater and a spray tower which are sequentially connected to a flue gas outlet of a boiler body, the heating system further comprising a temperature raising component, a first air heater and a second air heater;
[0006] The inlet of the heating component is connected to the liquid outlet of the spray tower, the steam outlet and the hot solution outlet of the heating component are connected to the first heater and the second heater respectively, and the solution outlet and the hot air outlet of the second heater are connected to the liquid inlet of the spray tower and the air preheater respectively; wherein,
[0007] The heating component is used to heat the liquid from the spray tower to obtain water vapor and hot solution; the air outlet of the first air heater is connected to the air inlet of the second air heater, and the air inlet of the first air heater is used to receive first temperature wind, which is heated by water vapor and then by hot solution to become second temperature wind, and the second temperature wind enters the air preheater.
[0008] Optionally, the spray tower comprises a hollow tower body and at least one spray pipe located in the tower body;
[0009] The two ends of the spray pipe are respectively connected to the two side walls of the tower body, and one end of the spray pipe is connected to the liquid inlet of the tower body;
[0010] A plurality of spray holes are provided on one side of the spray pipe facing the bottom surface of the tower body, and the smoke inlet of the tower body is located between the liquid inlet and the liquid outlet of the tower body.
[0011] Optionally, the spray pipe is provided with a plurality of the spray holes at equal intervals along its length direction.
[0012] Optionally, the spray tower includes a plurality of spray pipes, and the plurality of spray pipes are evenly distributed in the tower body with the central axis of the tower body as the center of the circle.
[0013] Optionally, the temperature raising component includes an evaporator and a cold slag hopper;
[0014] The inlet of the evaporator is connected to the liquid outlet of the spray tower, and the steam outlet and the hot solution outlet of the evaporator are connected to the first heater and the second heater respectively;
[0015] A first heat exchange tube is also arranged in the evaporator, the outlet of the first heat exchange tube is connected to the gas inlet of the cold slag hopper through a circulation fan, and the gas outlet of the cold slag hopper is connected to the inlet of the first heat exchange tube;
[0016] The inlet of the cold slag hopper is connected to the large slag outlet of the boiler body, and is used to receive the large slag after combustion in the boiler body, and heat the first heat exchange tube through the large slag, so that the liquid in the evaporator evaporates to form the water vapor and the hot solution.
[0017] Optionally, the temperature raising component further includes a conveying member;
[0018] The conveyor is arranged at the bottom of the cold slag bucket to receive the large slag, and the transmission direction of the conveyor is opposite to the gas flow direction in the cold slag bucket, so that the large slag and the gas in the cold slag bucket can perform reverse convection heat exchange.
[0019] Optionally, the conveying member includes a conveying gear and a conveying belt;
[0020] The transmission gear is arranged at the bottom of the cold slag bucket, and the conveyor belt transmission is arranged on the transmission gear to discharge the large slag through the discharge port of the cold slag bucket.
[0021] Optionally, a second heat exchange tube is provided in the first air heater, an inlet of the second heat exchange tube is connected to the steam outlet of the evaporator, and an outlet of the second heat exchange tube is connected to the water reservoir through a first booster water pump;
[0022] A third heat exchange tube is arranged in the second air heater, the inlet of the third heat exchange tube is connected to the hot solution outlet of the evaporator, and the solution outlet of the third heat exchange tube is connected to the liquid inlet of the spray tower through a second booster water pump.
[0023] Optionally, the heating system further comprises an economizer, a dust collector, a desulfurization tower and a chimney;
[0024] The economizer is arranged in series between the boiler body and the air preheater, the dust collector and the desulfurization tower are arranged in series between the air preheater and the spray tower in sequence, and the chimney is connected to the flue gas outlet arranged at the top of the spray tower.
[0025] On the other hand, an embodiment of the present disclosure provides a thermal power unit, which adopts the heating system described above, and the heating system is arranged in the tail flue of the thermal power unit.
[0026] The thermal power unit and heating system thereof of the embodiments of the present disclosure can save high-grade auxiliary steam, improve the energy-saving effect of the unit, reduce the coal consumption of the unit, and prevent cold-end corrosion of the air preheater. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 This is a partial structural schematic diagram of a heating system for a thermal power unit according to an embodiment of the present disclosure;
[0028] Figure 2 This is a schematic diagram of another part of the heating structure of a heating system for a thermal power unit according to another embodiment of the present disclosure. DETAILED DESCRIPTION
[0029] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, the present disclosure is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.
[0030] like Figure 1 and Figure 2 As shown, a heating system 100 for a thermal power unit includes an air preheater 120 and a spray tower 130 which are sequentially connected to the flue gas outlet of a boiler body 110, and the heating system 100 also includes a heating component 140, a first air heater 150, and a second air heater 160. The inlet of the heating component 140 is connected to the liquid outlet of the spray tower 130, the steam outlet and the hot solution outlet of the heating component 140 are connected to the first air heater 150 and the second air heater 160 respectively, and the solution outlet and the hot air outlet of the second air heater 160 are connected to the liquid inlet of the spray tower 130 and the air preheater 120 respectively.
[0031] The heating component 140 is used to heat the liquid from the spray tower 130 to obtain water vapor and hot solution. The air outlet of the first air heater 150 is connected to the air inlet of the second air heater 160. The air inlet of the first air heater 150 is used to receive the first temperature wind, which is heated by water vapor and then heated by hot solution to become the second temperature wind, and the second temperature wind enters the air preheater 120.
[0032] Specifically, Figure 1 and Figure 2 As shown, the heating system 100 is arranged in the tail flue of the thermal power unit, and the flue gas generated by the boiler combustion passes through the boiler body 110, the economizer 170, the air preheater 120, the dust collector 180, the desulfurization tower 181, the spray tower 130 and the chimney 190 in sequence. The flue gas inlet of the chimney 190 is connected to the flue gas outlet arranged at the top of the spray tower 130, and the flue gas is finally discharged from the chimney 190.
[0033] The spray tower 130 sprays a concentrated solution to cool the flue gas therein, and the concentrated solution absorbs part of the water vapor in the flue gas and becomes a dilute solution and is stored at the bottom of the spray tower 130. The dilute solution at the bottom of the spray tower 130 flows into the heating component 140, and the dilute solution is evaporated to form water vapor and hot solution (concentrated solution) under the heating action of the heating component 140. The water vapor enters the first heater 150, and the hot solution enters the second heater 160. The first heater 150 heats the first temperature wind through the water vapor therein, and the heated first temperature wind enters the second heater 160. The second heater 160 reheats the hot solution therein to form the second temperature wind, and the second temperature wind is transported to the air preheater 120. The hot solution after heat exchange is transported to the spray tower 130 and sprayed as a concentrated solution.
[0034] It is not difficult to understand that the concentrated solution uses a water-absorbing solution. The first temperature wind is low temperature wind, which is heated by water vapor to form medium temperature wind, and the medium temperature wind is heated by hot solution to form high temperature wind, which is the second temperature wind.
[0035] The heating system for a thermal power unit according to the embodiment of the present disclosure can save high-grade auxiliary steam, improve the energy-saving effect of the unit, reduce the coal consumption of the unit, and reduce the relative humidity of the flue gas discharged into the atmosphere. In addition, by heating the first temperature wind to the second temperature wind and then transmitting it to the air preheater, cold end corrosion of the air preheater can be prevented.
[0036] For example, Figure 1 and Figure 2As shown, the spray tower 130 includes a hollow tower body 131 and at least one spray pipe 132 located in the tower body 131. The two ends of the spray pipe 132 are respectively connected to the two side walls of the tower body 131, and one end of the spray pipe 132 is connected to the liquid inlet 1311 of the tower body 131. The spray pipe 132 is provided with a plurality of spray holes 133 on one side facing the bottom surface of the tower body 131, and the smoke inlet of the tower body 131 is located between the liquid inlet 1311 and the liquid outlet 1312 of the tower body 131.
[0037] Specifically, Figure 1 and Figure 2 As shown, the spray pipe 132 is arranged at the upper part of the tower body 131. As a specific example, the spray tower 130 includes a plurality of spray pipes 132, and the plurality of spray pipes 132 are evenly distributed in the tower body 131 with the central axis point of the tower body 131 as the center. A plurality of spray holes 133 are opened on the lower side of each spray pipe 132. Figure 2 As shown, a concentrated solution at 40°C is sprayed downward from the spray hole 133, fully contacts with the flue gas from bottom to top, and reduces the saturated flue gas flowing out of the desulfurization tower 181 from 80°C to 60°C. The concentrated solution absorbs part of the water vapor in the flue gas and becomes a dilute solution which is stored at the bottom of the tower body 131. The unsaturated flue gas after cooling is discharged into the atmosphere through the chimney 190.
[0038] Furthermore, the spray pipe 132 is provided with a plurality of spray holes 133 at equal intervals along its length direction.
[0039] For example, Figure 2 As shown, the heating component 140 includes an evaporator 141 and a cold slag hopper 142. The inlet of the evaporator 141 is connected to the liquid outlet of the spray tower 130, and the steam outlet and the hot solution outlet of the evaporator 141 are respectively connected to the first heater 150 and the second heater 160. A first heat exchange tube (not marked in the figure) is also arranged in the evaporator 141, and the outlet of the first heat exchange tube is connected to the gas inlet of the cold slag hopper 142 through the circulation fan 200, and the gas outlet of the cold slag hopper 142 is connected to the inlet of the first heat exchange tube.
[0040] The feed port of the cold slag hopper 142 is connected to the large slag outlet of the boiler body 110, and is used to receive the large slag after combustion in the boiler body 110, and heat the first heat exchange tube through the large slag, so that the liquid in the evaporator 141 evaporates to form the water vapor and the hot solution.
[0041] Specifically, Figure 2As shown, the evaporator 141 is divided into an upper water vapor section and a lower hot solution section. A first heat exchange tube, such as a serpentine heat exchange tube, is arranged in the evaporator 141. The evaporator 141 draws a dilute solution from the bottom of the spray tower 130 into the evaporator 141, and the high-temperature heat source inside the first heat exchange tube evaporates the water in the dilute solution into water vapor and distributes it in the upper water vapor section, and the remaining concentrated solution (hot solution) remains in the lower hot solution section.
[0042] The high-temperature heat source inside the first heat exchange tube utilizes the high-temperature ash residue remaining after combustion in the boiler body 110, such as the 800°C high-temperature ash residue remaining after combustion in the boiler body 110 falling into the cold ash bucket 142 as a heating source. As an example, the circulating fan 200 extracts the 80°C low-temperature gas in the first heat exchange tube and transports it to the cold ash bucket 142. The low-temperature gas exchanges heat with the high-temperature ash residue in the cold ash bucket 142 to heat up to 200°C high-temperature gas. The high-temperature gas then enters the first heat exchange tube as a high-temperature heat source to heat the 60°C dilute solution to 80°C, and the water in the dilute solution is evaporated into water vapor.
[0043] Furthermore, the heating component further includes a conveyor 143. The conveyor 143 is arranged at the bottom of the cold slag bucket 142 to receive the large slag, and the transmission direction of the conveyor 143 is opposite to the gas flow direction in the cold slag bucket 142, so that the large slag and the gas in the cold slag bucket 142 can perform reverse convection heat exchange.
[0044] Specifically, the 800°C high-temperature slag remaining after combustion in the boiler body 110 falls onto the conveying member 143 in the cold slag bucket 142, and the circulating fan 200 extracts the 80°C low-temperature gas in the first heat exchange tube and transports it to the cold slag bucket 142, where it undergoes reverse convection heat exchange with the high-temperature slag on the conveying member 143 and is heated into a 200°C high-temperature gas. The high-temperature gas then enters the first heat exchange tube as a high-temperature heat source to heat the 60°C dilute solution to 80°C, and the water in the dilute solution is evaporated into water vapor.
[0045] As a specific example, Figure 2 As shown, the conveying member 143 includes a conveying gear 1431 and a conveying belt 1432. The conveying gear 1431 is arranged at the bottom of the cold slag bucket 142, and the conveying belt 1432 is driven by the conveying gear 1431 to discharge the large slag through the discharge port of the cold slag bucket 142.
[0046] For example, Figure 2As shown, a second heat exchange tube (not marked in the figure) is provided in the first air heater 150, the inlet of the second heat exchange tube is connected to the steam outlet of the evaporator 141, and the outlet of the second heat exchange tube is connected to the water reservoir 400 through the first booster water pump 300. A third heat exchange tube (not marked in the figure) is provided in the second air heater 160, the inlet of the third heat exchange tube is connected to the hot solution outlet of the evaporator 141, and the solution outlet of the third heat exchange tube is connected to the liquid inlet of the spray tower 130 through the second booster water pump 500.
[0047] Specifically, Figure 2 As shown, a second heat exchange tube is provided in the first air heater 150, and a third heat exchange tube is provided in the second air heater 160. Both the second heat exchange tube and the third heat exchange tube can be configured as tubular heat exchangers. As a specific example, after the first temperature wind (low temperature wind) of -25°C enters the first air heater 150, under the action of the second heat exchange tube, the first temperature wind exchanges heat with the 80°C water vapor from the evaporator 141, and the first temperature wind is heated to 5°C to obtain the medium temperature wind mentioned above, and the water vapor is condensed from 80°C into 40°C cooling water, and is pumped into the water reservoir 400 by the first booster water pump 300 for recycling.
[0048] The 5°C medium temperature wind enters the second air heater 160. Under the action of the third heat exchange tube, the 5°C medium temperature wind exchanges heat with the 80°C concentrated solution from the evaporator 141, and the 5°C medium temperature wind is heated to 30°C to form high temperature wind (second temperature wind). The high temperature wind enters the air preheater 120. After the concentrated solution temperature is cooled from 80°C to 40°C, it is pumped into the spray pipe 132 in the spray tower 130 by the second booster water pump 500, and contacts and exchanges heat with the flue gas through the spray hole 133.
[0049] It should be noted that the high-temperature air obtained after being heated by the first and second air heaters needs to continue to exchange heat with the flue gas in the air heat exchanger to increase the temperature of the flue gas at the air preheater outlet. As mentioned above, the purpose of heating the low-temperature air to high-temperature air is to increase the air temperature entering the air preheater, thereby preventing the cold end wall temperature of the air preheater from being too low and causing low-temperature corrosion.
[0050] The heating system for a thermal power unit of the embodiment of the present disclosure (1) effectively improves the inlet air temperature of the air preheater: the first temperature air entering the air preheater is heated from -25°C to 30°C before entering the air preheater for secondary heating, thereby increasing the wall temperature of the cold end of the air preheater, preventing equipment corrosion caused by the wall temperature being lower than the acid dew point, and reducing the blockage of the cold end of the air preheater caused by the condensation of ammonium bisulfate.
[0051] (2) Effectively utilize the waste heat of the tail flue gas: Use the waste heat of the flue gas and the waste heat of the slag after combustion to heat the first temperature air, improve boiler efficiency, avoid resource waste, save high-grade auxiliary steam extraction, reduce unit coal consumption, and improve unit operation economy.
[0052] (3) Recycling water vapor in flue gas: Use a water-absorbing solution to absorb water vapor in flue gas, use a high-temperature heat source to evaporate and separate it, then use heat exchange to cool it down and condense it into water for recycling, saving water resources.
[0053] (4) Reduce the relative humidity of flue gas discharged into the atmosphere: The flue gas after desulfurization in the desulfurization tower is saturated flue gas. After contacting with the water-absorbing solution, part of the water vapor is adsorbed, and the temperature is reduced while turning it into unsaturated flue gas. At this time, it is discharged into the atmosphere to avoid the "white smoke" produced by the condensation of water vapor in the flue gas into water mist when it is cooled, thereby reducing visual pollution to the environment.
[0054] On the other hand, the embodiment of the present disclosure provides a thermal power unit, which adopts the heating system described above. The specific structure of the heating system can refer to the relevant records above, and will not be described in detail here. The heating system is arranged in the tail flue of the thermal power unit.
[0055] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and substance of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the present disclosure.
Claims
1. A heating system for a thermal power unit, characterized in that: The heating system comprises an air preheater and a spray tower which are sequentially connected to the smoke outlet of the boiler body, and the heating system also comprises a temperature raising component, a first air heater and a second air heater; The inlet of the heating component is connected to the liquid outlet of the spray tower, the steam outlet and the hot solution outlet of the heating component are connected to the first heater and the second heater respectively, and the solution outlet and the hot air outlet of the second heater are connected to the liquid inlet of the spray tower and the air preheater respectively; wherein, The heating component is used to heat the liquid from the spray tower to obtain water vapor and hot solution; the air outlet of the first air heater is connected to the air inlet of the second air heater, and the air inlet of the first air heater is used to receive first temperature wind, which is heated by water vapor and then by hot solution to become second temperature wind, and the second temperature wind enters the air preheater.
2. The heating system for a thermal power unit according to claim 1, characterized in that: The spray tower comprises a hollow tower body and at least one spray pipe located in the tower body; The two ends of the spray pipe are respectively connected to the two side walls of the tower body, and one end of the spray pipe is connected to the liquid inlet of the tower body; A plurality of spray holes are provided on one side of the spray pipe facing the bottom surface of the tower body, and the smoke inlet of the tower body is located between the liquid inlet and the liquid outlet of the tower body.
3. The heating system for a thermal power unit according to claim 2, characterized in that: The spray pipe is provided with a plurality of spray holes at equal intervals along its length direction.
4. The heating system for a thermal power unit according to claim 2, characterized in that: The spray tower comprises a plurality of spray pipes, and the plurality of spray pipes are evenly distributed in the tower body with the central axis point of the tower body as the center of the circle.
5. The heating system for a thermal power unit according to any one of claims 1 to 4, characterized in that: The temperature raising component comprises an evaporator and a cold slag hopper; The inlet of the evaporator is connected to the liquid outlet of the spray tower, and the steam outlet and the hot solution outlet of the evaporator are connected to the first air heater and the second air heater respectively; A first heat exchange tube is also arranged in the evaporator, the outlet of the first heat exchange tube is connected to the gas inlet of the cold slag hopper through a circulation fan, and the gas outlet of the cold slag hopper is connected to the inlet of the first heat exchange tube; The inlet of the cold slag hopper is connected to the large slag outlet of the boiler body, and is used to receive the large slag after combustion in the boiler body, and heat the first heat exchange tube through the large slag, so that the liquid in the evaporator evaporates to form the water vapor and the hot solution.
6. The heating system for a thermal power unit according to claim 5, characterized in that: The temperature raising component also includes a conveying member; The conveyor is arranged at the bottom of the cold slag bucket to receive the large slag, and the transmission direction of the conveyor is opposite to the gas flow direction in the cold slag bucket, so that the large slag and the gas in the cold slag bucket can perform reverse convection heat exchange.
7. The heating system for a thermal power unit according to claim 6, characterized in that: The conveying member includes a conveying gear and a conveying belt; The transmission gear is arranged at the bottom of the cold slag bucket, and the conveyor belt transmission is arranged on the transmission gear to discharge the large slag through the discharge port of the cold slag bucket.
8. The heating system for a thermal power unit according to claim 5, characterized in that: A second heat exchange tube is provided in the first air heater, the inlet of the second heat exchange tube is connected to the steam outlet of the evaporator, and the outlet of the second heat exchange tube is connected to the water reservoir through the first booster water pump; A third heat exchange tube is arranged in the second air heater, the inlet of the third heat exchange tube is connected to the hot solution outlet of the evaporator, and the solution outlet of the third heat exchange tube is connected to the liquid inlet of the spray tower through a second booster water pump.
9. The heating system for a thermal power unit according to any one of claims 1 to 4, characterized in that: The heating system also includes an economizer, a dust collector, a desulfurization tower and a chimney; The economizer is arranged in series between the boiler body and the air preheater, the dust collector and the desulfurization tower are arranged in series between the air preheater and the spray tower in sequence, and the chimney is connected to the flue gas outlet arranged at the top of the spray tower.
10. A thermal power unit, characterized in that: A heating system as claimed in any one of claims 1 to 9 is adopted, wherein the heating system is arranged in the tail flue of the thermal power unit.