High-efficiency combined preheater system for boiler of thermal power plant
By adopting a combination design of tube and rotary air preheaters in thermal power plant boilers, primary and secondary air are independently heated, and high-temperature flue gas is used to heat the feed water, the problem of high air leakage rate and air temperature is solved, and the effect of efficient energy saving and catalyst life is achieved.
Patent Information
- Application Number
- CN202510532062.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-25
- Publication Date
- 2025-08-01
AI Technical Summary
The existing thermal power plant air preheaters have problems such as high air leakage rate, large energy consumption, losses caused by mismatch in the air temperature of the coal mill, and catalyst blockage, and cannot effectively utilize the flue gas heat at the tail of the boiler.
The combined design of a tube air preheater and a rotary air preheater is adopted to heat the primary and secondary air respectively, and the feed water is heated using high-temperature flue gas to heat the primary air temperature, and the feed water flow rate and temperature regulation are adjusted, and the denitrification and dilution air are independently heated to reduce air leakage and improve heat utilization.
The primary air leakage rate is reduced, the power consumption is reduced, the system efficiency is improved, the catalyst life is improved, the standard coal is saved, the boiler efficiency is improved by about 0.7%, the fan power consumption is reduced, and the burden on dust collectors and desulfurization systems is reduced.
Smart Images
Figure CN120402885A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of thermal power equipment, and particularly relates to a high-efficiency combined preheater system for a boiler in a thermal power plant. Background Art
[0002] At present, the air preheaters configured in coal-fired power plants generally adopt Ljungstrom rotary air preheaters, which use metal heat storage elements to achieve heat exchange between flue gas and cold primary air and secondary air entering the furnace. Its advantages are small metal consumption and small heat transfer end difference. The disadvantage is that the air leakage of the preheater brings higher energy consumption. Since the operating wind pressure of the primary air in the preheater is much higher than that of the secondary air and flue gas, the air leakage volume on the primary air side is very large. The air leakage causes a large power consumption of the primary air fan, and at the same time increases the burden on the induced draft fan and the dust removal and desulfurization system, and also increases the investment and auxiliary power consumption of the corresponding system.
[0003] In addition, from the perspective of boiler combustion analysis, the final required heating temperatures for primary air and secondary air are different. However, at present, the preheaters in thermal power plants generally heat the hot primary air and hot secondary air to about 350°C at the same time. For the primary air system, the requirements for the air temperature at the inlet of the coal mill vary greatly for different coal types. For most coal types except lignite, the required air temperature at the inlet of the coal mill is between 200 and 280°C. Therefore, in order to meet the requirements of the air temperature at the inlet of the coal mill, the common practice is to mix about 20°C of cold air into the hot air at the inlet of the coal mill until the temperature meets the requirements. During this process, the hot and cold air with a temperature difference exceeding 320°C are directly mixed, resulting in a large loss. Summary of the Invention
[0004] The purpose of the present invention is to solve the defects and deficiencies in the prior art, and design a high-efficiency combined preheater system for a boiler in a thermal power plant that can reduce the air leakage rate, reduce power consumption, and improve system efficiency.
[0005] To achieve the above purpose, the technical solution adopted by the present invention is: a high-efficiency combined preheater system for a boiler in a thermal power plant, including a tubular air preheater for heating primary air and a rotary air preheater for heating secondary air arranged at the tail of the boiler. The flue gas inlets of the tubular air preheater and the rotary air preheater are both connected to the flue gas outlet of the denitration system. The flue gas outlets of the tubular air preheater and the rotary air preheater are both connected to the dust collector, and a feed water heat exchanger is also provided between the flue gas inlet of the tubular air preheater and the flue gas outlet of the denitration system.
[0006] Preferably, the primary air inlet of the tubular air preheater is connected to the primary air fan.
[0007] Preferably, the primary air outlet of the tubular air preheater is connected to the coal mill and the denitration dilution air system.
[0008] Preferably, the temperature of the hot primary air entering the coal mill from the tubular air preheater is 200 - 280 °C.
[0009] Preferably, the hot primary air of the tubular air preheater enters the denitration dilution air system through the clean air channel.
[0010] Preferably, a staged economizer is arranged at the flue gas outlet of the denitration system. The water inlet of the feed water heat exchanger is equipped with a temperature and flow regulating device, and the water outlet of the feed water heat exchanger is connected to the staged economizer.
[0011] Preferably, the secondary air inlet of the rotary air preheater is connected to the forced draft fan.
[0012] Preferably, the temperature of the hot secondary air at the secondary air outlet of the rotary air preheater is 350 °C.
[0013] Preferably, the outlet of the dust collector is connected to the induced draft fan.
[0014] After adopting the above technical solutions, a high-efficiency combined preheater system for a thermal power plant boiler provided by the present invention has the following beneficial effects:
[0015] (1) By constructing a combined preheater system, the present invention makes the processes of heating the primary air and the secondary air independent of each other. The use of a tubular air preheater can minimize the primary air leakage rate, reduce the power consumption of the primary air, heat the feed water using the high-temperature flue gas section on the flue gas side of the primary air circuit, and control the heat absorption of the primary air preheater by controlling the feed water flow and the inlet water temperature, thereby adjusting the primary air temperature and avoiding the loss caused by cold air mixing. In addition, using dust-free hot primary air as the denitration dilution air can improve the problem of catalyst blockage;
[0016] (2) Adopting the present invention can make the heat of the flue gas at the tail of the boiler be used more reasonably and effectively. For projects where the inlet air temperature required by the coal mill is 200 °C, the boiler efficiency can be increased by about 0.7%. Calculated based on the standard coal consumption of the unit being 300 g / kWh and the annual operation time being 50,000 hours, each 1000 MW coal-fired power generation unit can save 10,500 tons of standard coal annually;
[0017] (3) Adopting the present invention, a 1000 MW coal-fired power generation unit can reduce the power consumption of the primary air fan during operation. Calculated based on the primary air side leakage air volume of the rotary preheater being 40 Kg / S, the power consumption of the primary air fan during operation can be reduced by about 800 kW. At the same time, the power consumption of the dust collector, desulfurization island, and induced draft fan during operation can also be reduced;
[0018] (4) All the primary air in the present invention passes through the tubular air preheater for heat exchange, improving the mismatch between the heat of the flue gas and the cold air, and increasing the utilization rate of the flue gas waste heat;
[0019] (5) In the present invention, the dilution air for denitrifying ammonia can directly use the primary hot air, without worrying about the problem of blockage in the SCR area catalyst, reducing the maintenance workload of the SCR catalyst and increasing the catalyst life. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 It is a schematic structural diagram of a high-efficiency combined preheater system for a thermal power plant boiler according to the present invention.
[0021] Wherein: boiler 1, tubular air preheater 2, rotary air preheater 3, denitrification system 4, dust collector 5, feed water heat exchanger 6, primary air fan 7, coal mill 8, denitrification dilution air system 9, staged economizer 10, forced draft fan 11, induced draft fan 12. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0022] The present invention will be further clearly and completely described below in conjunction with the drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.
[0023] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0024] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn according to the actual proportional relationship. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed herein, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.
[0025] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by orientation words such as "front, back, top, bottom, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom", etc. is usually based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description. Without contrary explanation, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the protection scope of the present invention; the orientation words "inside, outside" refer to the inside and outside relative to the contour of each component itself.
[0026] For ease of description, spatial relative terms such as "above...", "over...", "on the upper surface of...", "above" etc. can be used here to describe the spatial positional relationship of one device or feature to other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the drawings for the device. For example, if the device in the drawing is inverted, the device described as "above other devices or structures" or "over other devices or structures" will then be positioned "below other devices or structures" or "under other devices or structures". Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations should be made for the spatial relative descriptions used here.
[0027] In addition, it should be noted that the use of words such as "first", "second", etc. to limit components is only for the convenience of distinguishing the corresponding components. Without otherwise stated, these words have no special meaning, and therefore should not be construed as a limitation on the protection scope of the present invention.
[0028] A high-efficiency combined preheater system for a boiler in a thermal power plant according to the present invention, as Figure 1As shown in the figure, it is used for a newly built unit or retrofit project with single reheat or double reheat. A combined integrated design of a tubular air preheater 2 and a rotary air preheater 3 is adopted at the tail of the boiler 1 to separate the heating paths of the primary air and the secondary air. Specifically, the flue gas inlet of the tubular air preheater 2 is connected to the flue gas outlet of the denitration system 4. A staged economizer 10 is arranged at the flue gas outlet of the denitration system 4. The primary air inlet of the tubular air preheater 2 is connected to the primary air fan 7. The primary air outlet of the tubular air preheater 2 is connected to the coal mill 8 and the denitration dilution air system 9. The flue gas outlet of the tubular air preheater 2 is connected to the dust collector 5. A feed water heat exchanger 6 is also arranged between the flue gas inlet of the tubular air preheater 2 and the flue gas outlet of the denitration system 4. The water inlet of the feed water heat exchanger 6 is equipped with a temperature and flow regulating device. The water outlet of the feed water heat exchanger 6 is connected to the staged economizer 10. By arranging the feed water heat exchanger 6 with serpentine tubes in the upstream flue of the tubular air preheater 2, part of the high-pressure feed water can be heated by the high-temperature flue gas (such as rising from 200 °C to 330 °C). Thus, the temperature of the flue gas upstream of the tubular air preheater 2 can be controlled by the feed water flow to adjust the temperature of the hot primary air, and the best utilization effect of the flue gas heat can be achieved.
[0029] Further, the temperature of the hot primary air entering the coal mill 8 from the tubular air preheater 2 is 200 - 280 °C. The hot primary air of the tubular air preheater 2 enters the denitration dilution air system 9 through a clean air channel, that is, the clean primary hot air heated by the tubular air preheater 2 is used for the denitration dilution air system 9.
[0030] The flue gas inlet of the rotary air preheater 3 is also connected to the flue gas outlet of the denitration system 4. The secondary air inlet of the rotary air preheater 3 is connected to the forced draft fan 11. The temperature of the hot secondary air at the secondary air outlet of the rotary air preheater 3 is 350 °C. The flue gas outlet of the rotary air preheater 3 is also connected to the dust collector 5. Further, the outlet of the dust collector 5 is connected to the induced draft fan 12.
[0031] When the high-efficiency combined preheater system of a thermal power plant boiler of the present invention is in use, the flue gas flow distribution entering the primary air system and the secondary air system at the flue gas outlet of the denitration system 4 at the boiler tail can be optimized online according to the operation requirements. All the primary air that needs to enter the coal mill 8 enters the tubular air preheater 2. The heating temperature of the primary air is based on the requirements of the coal mill 8. The heated hot primary air can directly enter the coal mill 8 without temperature adjustment. By integrating the feed water heat exchanger 6 in the high-temperature flue gas section upstream of the tubular air preheater 2, efficient heat utilization can be achieved and it can be used for the regulation of the primary air temperature. Specifically, the regulation of the primary air temperature includes coarse regulation and fine regulation. Coarse regulation is to determine the required primary air volume of the coal mill 8 according to the number of operating units of the coal mill 8, the coal quality, and the unit load rate, and control the flue gas volume entering the primary air system according to the best heat exchange ratio with the primary air to achieve the best heat exchange effect of the primary air tubular air preheater 2. Fine regulation is to adjust the temperature of the hot primary air by adjusting the feed water flow rate of the feed water heat exchanger 6 to control the flue gas temperature upstream of the primary air tubular air preheater 2 according to the required air temperature at the inlet of the coal mill 8.
[0032] In summary, the high-efficiency combined preheater system of a thermal power plant boiler provided by the present invention can further improve the operation efficiency of the coal power plant and solve the problems of high air leakage, loss, and catalyst blockage of the traditional rotary preheater, and has the advantages of energy conservation, economy, and reliability, meeting the technical requirements of the efficient and clean operation of thermal power plants.
[0033] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.
Claims
1. A high-efficiency combined preheater system for a thermal power plant boiler, characterized in that: It includes a tubular air preheater (2) arranged at the tail of the boiler (1) for heating primary air and a rotary air preheater (3) for heating secondary air. The flue gas inlets of the tubular air preheater (2) and the rotary air preheater (3) are both connected to the flue gas outlet of the denitration system (4). The flue gas outlets of the tubular air preheater (2) and the rotary air preheater (3) are both connected to the dust collector (5). And a feed water heat exchanger (6) is also provided between the flue gas inlet of the tubular air preheater (2) and the flue gas outlet of the denitration system (4).
2. The high-efficiency combined preheater system for a thermal power plant boiler according to claim 1, wherein: The primary air inlet of the tubular air preheater (2) is connected to a primary air fan (7).
3. A high-efficiency combined preheater system for a thermal power plant boiler according to claim 1, characterized in that: The primary air outlet of the tubular air preheater (2) is connected to a coal mill (8) and a denitration dilution air system (9).
4. A high-efficiency combined preheater system for a thermal power plant boiler according to claim 3, characterized in that: The temperature of the hot primary air entering the coal mill (8) from the tubular air preheater (2) is 200 - 280 °C.
5. The high-efficiency combined preheater system for a thermal power plant boiler according to claim 3, characterized in that: The hot primary air of the tubular air preheater (2) enters the denitration dilution air system (9) through a clean air channel.
6. A high-efficiency combined preheater system for a thermal power plant boiler according to claim 1, characterized in that: A staged economizer (10) is arranged at the flue gas outlet of the denitration system (4). The water inlet of the feed water heat exchanger (6) is equipped with a temperature and flow regulating device. The water outlet of the feed water heat exchanger (6) is connected to the staged economizer (10).
7. A high-efficiency combined preheater system for a thermal power plant boiler according to claim 1, characterized in that: The secondary air inlet of the rotary air preheater (3) is connected to a forced draft fan (11).
8. A high-efficiency combined preheater system for a thermal power plant boiler according to claim 1, characterized in that: The temperature of the hot secondary air at the secondary air outlet of the rotary air preheater (3) is 350 °C.
9. A high-efficiency combined preheater system for a thermal power plant boiler according to claim 1, characterized in that: The outlet of the dust collector (5) is connected to an induced draft fan (12).