CN219264242U - Waste heat utilization system of coal-fired generating set - Google Patents

Abstract

The utility model discloses a waste heat utilization system of a coal-fired power generation unit.A port of a flue gas conveying pipeline is a flue gas inlet communicated with a flue gas pipeline of a boiler, and the other port is sequentially communicated with an air preheater, a low-temperature economizer and an electric dust collector; one end of the primary air pipeline is communicated with the primary air fan, and the other end of the primary air pipeline is sequentially communicated with the air preheater and the temperature-adjusting heat-exchanging device and extends out of the temperature-adjusting heat-exchanging device to form a primary air outlet; one end of the secondary air pipeline is communicated with a secondary air blower, and the other end of the secondary air pipeline is sequentially communicated with the heater and the air preheater and extends out of the air preheater to form a secondary air outlet; the inlet end of the condensed water inlet pipeline is communicated with a condensed water system, the outlet end of the condensed water inlet pipeline is sequentially communicated with the water inlet ends of the heater, the first booster pump, the low-temperature economizer and the temperature-regulating heat exchange device, and the water outlet end of the temperature-regulating heat exchange device is communicated with the condensed water system through the first backflow pipeline. The utility model can improve the utilization rate of the waste heat.

Description

Waste heat utilization system of coal-fired generating set

Technical Field

The utility model relates to the technical field of waste heat utilization of coal-fired power generation units, in particular to a waste heat utilization system of a coal-fired power generation unit.

Background

The coal-fired generator set is a mechanical device for converting chemical energy of fossil fuel such as coal into electric energy.

For the existing coal-fired generator set, the high parameters of the set raise the water supply temperature of the boiler, so that the smoke temperature at the inlet of the air preheater is raised, and meanwhile, in order to improve the economy, the heat exchange area of the air preheater is increased, so that the temperature of hot air at the outlet of the air preheater is also raised, the temperature of hot primary air of a large-capacity set boiler is generally 320-360 ℃, and in order to improve the utilization rate of the hot primary air in the set boiler, the hot primary air of the set boiler is generally used for an inlet leading to a coal mill at present so as to be used for drying coal dust in the coal mill;

since the temperature of the air-powder mixture at the outlet of the coal mill is limited by safety, so that the primary air temperature at the inlet of the coal mill cannot be too high, and the temperature is generally required to be not higher than 270 ℃, almost all boilers except for part of lignite and anthracite units must be doped with cold air, namely: the hot primary air of the unit boiler is used for being introduced into the inlet of the coal mill after being mixed with cold air, so that coal dust in the coal mill is blown into the boiler, the temperature of the inlet of the coal mill is not excessively high, the safety is improved, and particularly when low-moisture and high-volatile coal is combusted, the doping amount of the cold air is large because the temperature requirement of the air dust at the outlet of the coal mill is low.

As shown in fig. 1: at present, the waste heat utilization system of the existing coal-fired generator set is as follows: the cold air generated by the air preheater is divided into two paths by the first fan 901, the first path is sent to the air preheater 902, the second path is blown to the inlet of the coal mill 904 by the air preheater primary air bypass 903, the air preheater 902 exchanges heat with the cold air of the corresponding path into hot primary air and then also blows the hot primary air to the inlet of the coal mill 904, so that the cold air of the first path is mixed with the cold air of the first path at the inlet of the coal mill 904, and then the mixed air of the cold air and the hot primary air is blown into the coal mill 904, so that the temperature of the inlet air of the coal mill 904 is generally not higher than 270 ℃, and the safety is ensured; meanwhile, the second fan 905 inputs cold air into the air preheater 902 to exchange heat through the air preheater 902 and then blow the cold air to the boiler 906 so as to play a role in supporting combustion of the boiler 906; meanwhile, high-temperature flue gas generated in the boiler 906 is discharged through the soot remover 907 after heat exchange through the air preheater 902.

However, in the existing waste heat utilization system of the coal-fired power generation unit, since the cold air generated by the first fan 901 is divided into two paths, and since the cold air amount flowing to the inlet of the coal mill 904 is required to be larger, the cold air amount directly flowing to the air preheater 902 is smaller, the heat exchange amount of the air preheater 902 is reduced, and since the high-temperature flue gas generated by the boiler 906 exchanges heat in the air preheater 902, when the heat exchange amount of the air preheater 902 is reduced, the flue gas temperature discharged from the air preheater 902 and the dust remover 907 sequentially is higher, so that the efficiency of the boiler 906 is reduced; moreover, the way of mixing the inlet of the coal mill 904 with the high-temperature primary air of the unit boiler by introducing a large amount of cold air into the inlet of the coal mill 904 to avoid the too high temperature of the inlet of the coal mill 904 not only needs to provide a large amount of cold air, but also does not utilize the heat of the high-temperature primary air of the unit boiler, so that the heat utilization rate of the waste heat utilization system of the existing coal-fired power generation unit is lower.

In addition, in the present air preheater primary air bypass 903, the amount of air blown to the coal mill is adjusted by providing a plurality of wind shields, so that the temperature of the mixed air at the inlet of the coal mill 904 can be adjusted, but there is a problem that the temperature of the mixed air at the inlet of the coal mill 904 is not accurately adjusted.

Therefore, how to provide a waste heat utilization system of a coal-fired power generation unit for improving the waste heat utilization rate is a technical problem that needs to be solved by those skilled in the art.

Disclosure of Invention

In view of the above, the present utility model provides a waste heat utilization system of a coal-fired power generator unit, which aims to solve at least some of the above technical problems.

In order to achieve the above purpose, the present utility model adopts the following technical scheme:

a waste heat utilization system for a coal-fired power generation unit, comprising: the system comprises a flue gas conveying pipeline, an air preheater, an electric dust collector, a low-temperature economizer, a primary air blower, a primary air pipeline, a temperature-adjusting heat exchange device, a secondary air pipeline, a secondary air blower, a warm air blower, a condensate water inlet pipeline, a first booster pump and a first backflow pipeline;

one port of the flue gas conveying pipeline is a flue gas inlet communicated with a flue gas pipeline of the boiler, and the other port is sequentially communicated with an air preheater, the low-temperature economizer and the electric dust collector;

one end of the primary air pipeline is communicated with the primary air fan, and the other end of the primary air pipeline is sequentially communicated with the air preheater and the temperature-adjusting heat exchange device and extends out of the temperature-adjusting heat exchange device to form a primary air outlet;

one end of the secondary air pipeline is communicated with the secondary air blower, and the other end of the secondary air pipeline is sequentially communicated with the heater and the air preheater and extends out of the air preheater to form a secondary air outlet;

the inlet end of the condensed water inlet pipeline is communicated with a condensed water system, the outlet end of the condensed water inlet pipeline is sequentially communicated with the heater, the first booster pump, the low-temperature economizer and the water inlet end of the temperature-adjusting heat exchange device, and the water outlet end of the temperature-adjusting heat exchange device is communicated with the condensed water system through the first backflow pipeline.

Preferably, the method further comprises: the inlet end of the second reflux pipeline is communicated with the condensed water inlet pipeline, the communicated position of the second reflux pipeline and the condensed water inlet pipeline is positioned between the low-temperature economizer and the temperature-adjusting heat exchange device and is close to the low-temperature economizer, and meanwhile, the outlet end of the second reflux pipeline is communicated with the condensed water system.

Preferably, the condensate system includes: the device comprises a condensate water conveying pipeline, a condensate water pump, an eighth low-pressure heater, a seventh low-pressure heater, a sixth low-pressure heater, a fifth low-pressure heater, a third high-pressure heater, a second high-pressure heater, a first high-pressure heater, a second booster pump and a deaerator, wherein the heat of the eighth low-pressure heater, the seventh low-pressure heater, the sixth low-pressure heater, the fifth low-pressure heater, the third high-pressure heater, the second high-pressure heater and the first high-pressure heater is increased in sequence;

one end of the condensate water conveying pipeline is communicated with the condensate water pump, and the other end of the condensate water conveying pipeline is sequentially communicated with the eighth low-pressure heater, the seventh low-pressure heater, the sixth low-pressure heater, the fifth low-pressure heater, the deaerator, the second booster pump, the third high-pressure heater, the second high-pressure heater and the first high-pressure heater;

the inlet end of the condensed water inlet pipeline, the outlet end of the second backflow pipeline and the outlet end of the first backflow pipeline are connected with the condensed water conveying pipeline, the inlet end of the first backflow pipeline is connected with the water outlet end of the temperature-adjusting heat exchange device, meanwhile, the inlet end of the condensed water inlet pipeline is close to the outlet end of the seventh low-pressure heater, the outlet end of the second backflow pipeline is close to the inlet end of the sixth low-pressure heater, and the outlet end of the first backflow pipeline is close to the inlet end of the deaerator.

Preferably, the method further comprises: the system comprises a first temperature sensor, a second temperature sensor, a first electric regulating valve, a second electric regulating valve and a controller;

the first temperature sensor and the second temperature sensor are both connected to the primary air pipe, the first temperature sensor is close to the air inlet end of the temperature-adjusting heat exchange device, and the second temperature sensor is close to the air outlet end of the temperature-adjusting heat exchange device;

the first electric regulating valve is connected to the condensate water inlet pipeline and is positioned between the temperature-regulating heat exchange device and the low-temperature economizer, and the second electric regulating valve is connected to the first backflow pipeline;

the controller is electrically connected with the first temperature sensor, the second temperature sensor, the first electric regulating valve and the second electric regulating valve respectively.

Compared with the prior art, the utility model discloses a waste heat utilization system of a coal-fired power generation unit, which can realize the following technical effects:

the utility model can reduce the temperature of the air led to the inlet of the coal mill by utilizing the waste heat of the coal-fired power generator unit, so that a great amount of cold air is not needed to be supplemented to the inlet of the coal mill, energy is saved, a plurality of heat exchanges can be carried out to be more efficiently utilized, and the utilization rate of the waste heat of the coal-fired power generator unit is improved.

The utility model is easy to cause the problem of cold end low temperature corrosion and blockage of the air preheater.

Drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present utility model, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a prior art waste heat utilization system for a coal-fired power unit;

fig. 2 is a schematic structural diagram of a waste heat utilization system of a coal-fired power generation unit according to the present utility model.

Wherein 901-the first fan; 902-an air preheater; 903—primary air bypass of the air preheater; 904—coal mill; 905-a second fan; 906-boiler; 907-cigar remover;

1-a flue gas conveying pipeline; 2-an air preheater; 3-an electric dust collector; 4-low-temperature economizer; 5-a primary fan; 6-a primary air pipeline; 7-a temperature-regulating heat exchange device; 8-a secondary air pipeline; 9-a secondary air blower; 10-a heater; 11-a condensate water inlet pipeline; 12-a first booster pump; 101-a smoke inlet; 102-a primary air outlet; 103-a secondary air outlet; 13-a condensate system; 14-a first return line; 15-a second return line; 131-a condensate delivery conduit; 132-a condensate pump; 133-eighth low pressure heater; 134-seventh low pressure heater; 135-sixth low pressure heater; 136-a fifth low pressure heater; 137-a third high pressure heater; 138-a second high pressure heater; 139-a first high pressure heater; 130-a second booster pump; 100 deaerator.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

In the description of the present utility model, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "inner", "outer", "front", "rear", "both ends", "one end", "the other end", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific direction, be configured and operated in the specific direction, and thus should not be construed as limiting the present utility model. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present utility model, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "provided," "connected," and the like are to be construed broadly, and may be fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

The embodiment of the utility model discloses a waste heat utilization system of a coal-fired power generating unit, which comprises the following components: a flue gas conveying pipeline 1, an air preheater 2, an electric dust collector 3, a low-temperature economizer 4, a primary air blower 5, a primary air pipeline 6, a temperature-adjusting heat exchange device 7, a secondary air pipeline 8, a secondary air blower 9, a heater 10, a condensate water inlet pipeline 11, a first booster pump 12 and a first backflow pipeline 14;

one port of the flue gas conveying pipeline 1 is a flue gas inlet 101 communicated with a flue gas pipeline of a boiler, and the other port is sequentially communicated with an air preheater 2, a low-temperature economizer 4 and an electric dust collector 3;

one end of a primary air pipeline 6 is communicated with a primary air fan 5, and the other end of the primary air pipeline is sequentially communicated with an air preheater 2 and a temperature-regulating heat exchange device 7 and extends out of the temperature-regulating heat exchange device 7 to form a primary air outlet 102;

one end of the secondary air pipeline 8 is communicated with a secondary air blower 9, and the other end of the secondary air pipeline is sequentially communicated with a warm air blower 10 and the air preheater 2 and extends out of the air preheater 2 to form a secondary air outlet 103;

the inlet end of the condensed water inlet pipe 11 is communicated with the condensed water system 13, the outlet end of the condensed water inlet pipe 11 is communicated with the water inlet ends of the heater 10, the first booster pump 12, the low-temperature economizer 4 and the temperature-adjusting heat exchange device 7 in sequence, and the water outlet end of the temperature-adjusting heat exchange device 7 is communicated with the condensed water system 13 through the first backflow pipe 14.

The working principle of the application is as follows:

the smoke inlet 101 of the smoke conveying pipeline 1 is used for being communicated with a smoke exhaust pipeline of a boiler, so that high-temperature smoke generated by the boiler is discharged through the electric dust collector 3 after passing through the air preheater 2 and the low-temperature economizer 4 in sequence;

the cold air generated by the secondary air blower 9 sequentially passes through the heater 10 and the air preheater 2 and is discharged through the secondary air outlet 103, and the air discharged from the secondary air outlet 103 can be introduced into the boiler through a pipeline so as to be used for improving the air quantity of boiler combustion, thereby improving the efficiency of boiler combustion;

the condensate water inlet pipeline 11 introduces condensate water in the condensate water system 13 into the heater 10, then sequentially passes through the first booster pump 12, the low-temperature economizer 4 and the water inlet end of the temperature-regulating heat exchange device 7, finally comes out from the water outlet end of the temperature-regulating heat exchange device 7, and then flows back to the condensate water system 13 through the first backflow pipeline 14;

after passing through the air preheater 2 and the temperature-adjusting heat-exchanging device 7 in sequence, the cold air generated by the primary air blower 5 is discharged through the primary air outlet 102, and the air discharged from the primary air outlet 102 can be introduced into the coal mill through a pipeline so as to be used for blowing the coal dust in the coal mill to the boiler.

By adopting the above technical scheme, after the warm air ware 10 carries out heat exchange with the received cold wind that comes from the overgrate air machine 9 and comes from the high temperature condensate water in the condensate water system 13, then cold wind from overgrate air machine 9 changes into hot-blast back flow direction air heater 2 through warm air ware 10 to be difficult for making the flue gas temperature that gets into in air heater 2 through flue gas pipeline 1 lower, then on the one hand: the temperature of the sulfur-containing medium in the flue gas is not easy to be lower than the acid path point of the sulfur-containing medium, so that the problem of low-temperature corrosion of the cold end of the air preheater 2 is not easy to occur; on the other hand, the problems of ammonia bisulfate condensation and the like caused by ammonia escape in the SCR system in the coal-fired power generation unit (the problems of ammonia bisulfate condensation and the like which are easy to cause if the temperature of flue gas in the air preheater 2 is lower at the moment, are well known to the person skilled in the art and are not repeated here) are not easy to occur, so that the air preheater 2 is not easy to be blocked;

because the temperature of the flue gas entering the air preheater 2 is very high, cold air from the secondary air blower 9 is converted into hot air by the air heater 10 and flows to the air preheater 2, and the hot air can be further subjected to heat exchange with high-temperature flue gas in the air preheater 2 so as to further improve the temperature, and when the flue gas is introduced into the boiler for supporting combustion, the combustion rate of the boiler can be further improved;

the condensed water temperature after heat exchange by the air heater 10 is reduced, and then the condensed water is pumped to the low-temperature economizer 4 by the first booster pump 12, meanwhile, the high-temperature flue gas is cooled after heat exchange by the air preheater 2 and then enters the low-temperature economizer 4, and the condensed water after heat exchange by the air heater 10 and the flue gas after heat exchange by the air preheater 2 are subjected to heat exchange again in the low-temperature economizer 4, so that the temperature of the flue gas can be further reduced, and finally the flue gas is discharged from the electric dust collector 3, so that the temperature of the flue gas discharged by the application is lower, and the boiler can have higher working efficiency;

the temperature of the condensed water after heat exchange by the low-temperature economizer 4 is increased, and the condensed water flows to the temperature-adjusting heat-exchanging device 7, meanwhile, cold air generated by the primary fan 5 firstly enters the air preheater 2 to exchange heat with high-temperature flue gas, then enters the temperature-adjusting heat-exchanging device 7, and exchanges heat with the condensed water after heat exchange by the low-temperature economizer 4 in the temperature-adjusting heat-exchanging device 7, so that the temperature of the condensed water after heat exchange by the temperature-adjusting heat-exchanging device 7 can be further increased, and then the condensed water can flow back to the condensed water system 13 through the first backflow pipeline 14 to utilize the heat absorbed by the condensed water to exhaust the extraction steam of the condensed water system 13, thereby reducing the heat consumption value of the steam turbine and obtaining energy-saving benefits (at present, the heat generated by the steam extraction steam of the steam turbine is used for being provided for the condensed water system 13 to heat, and when the heat of the condensed water system 13 is increased, the heat of the condensed water system 13 can make the extraction steam of less do work); meanwhile, the temperature of the air subjected to heat exchange by the temperature-adjusting heat exchange device 7 is reduced, and the air is discharged to the inlet of the coal mill, so that a great amount of cold air does not need to be supplemented to the inlet of the coal mill, and energy is saved.

Therefore, the utility model can not only be used for reducing the temperature of the air led to the inlet of the coal mill by utilizing the waste heat of the coal-fired power generation unit so as to save energy without supplementing a large amount of cold air to the inlet of the coal mill, but also can perform a plurality of heat exchanges to be more efficiently utilized, thereby improving the utilization rate of the waste heat of the coal-fired power generation unit.

In order to further optimize the technical scheme, the method further comprises the following steps: the inlet end of the second reflux pipeline 15 is communicated with the condensate water inlet pipeline 11, and the communicated position of the second reflux pipeline 15 and the condensate water inlet pipeline 11 is positioned between the low-temperature economizer 4 and the temperature-adjusting heat exchange device 7 and is close to the low-temperature economizer 4, and meanwhile, the outlet end of the second reflux pipeline 15 is communicated with the condensate water system 13.

By adopting the technical scheme, part of condensed water subjected to heat exchange by the low-temperature economizer 4 flows to the condensed water system 13 through the first return pipeline 14, and the other part flows to the condensed water system 13 through the second return pipeline 15.

To further optimize the above solution, the condensate system 13 comprises: the heat of the condensate water conveying pipe 131, the condensate water pump 132, the eighth low-pressure heater 133, the seventh low-pressure heater 134, the sixth low-pressure heater 135, the fifth low-pressure heater 136, the third high-pressure heater 137, the second high-pressure heater 138, the first high-pressure heater 139, the second booster pump 130, and the deaerator 100 increases in sequence, and the heat of the eighth low-pressure heater 133, the seventh low-pressure heater 134, the sixth low-pressure heater 135, the fifth low-pressure heater 136, the third high-pressure heater 137, the second high-pressure heater 138, and the first high-pressure heater 139 increases in sequence;

one end of the condensate water conveying pipeline 131 is communicated with the condensate water pump 132, and the other end is communicated with an eighth low-pressure heater 133, a seventh low-pressure heater 134, a sixth low-pressure heater 135, a fifth low-pressure heater 136, the deaerator 100, a second booster pump 130, a third high-pressure heater 137, a second high-pressure heater 138 and a first high-pressure heater 139 in sequence;

the inlet end of the condensed water inlet pipe 11, the outlet end of the second backflow pipe 15 and the outlet end of the first backflow pipe 14 are all connected with the condensed water conveying pipe 131, the inlet end of the first backflow pipe 14 is connected with the water outlet end of the temperature-adjusting heat exchanging device 7, meanwhile, the inlet end of the condensed water inlet pipe 11 is close to the outlet end of the seventh low-pressure heater 134, the outlet end of the second backflow pipe 15 is close to the inlet end of the sixth low-pressure heater 135, and the outlet end of the first backflow pipe 14 is close to the inlet end of the deaerator 100.

The water vapor generated by the boiler is transmitted to the steam turbine to do work, after the water vapor generated by the steam turbine is condensed into condensed water, the condensed water is pumped to the condensed water conveying pipeline 131 by the condensed water pump 13, and flows to the eighth low-pressure heater 133, the seventh low-pressure heater 134, the sixth low-pressure heater 135, the fifth low-pressure heater 136, the deaerator 100, the second booster pump 130, the third high-pressure heater 137, the second high-pressure heater 138 and the first high-pressure heater 139 in sequence through the condensed water conveying pipeline 131 and flows out.

Since the above structure of the condensation water system 13 is the prior art, the description thereof will not be repeated herein.

By adopting the technical scheme, the condensed water part subjected to heat exchange by the low-temperature economizer 4 flows into the deaerator 100 through the first return pipeline 14, so that the heat absorbed by the condensed water part can be particularly used for exhausting the steam extraction of the deaerator 100, and the heat consumption value of the steam turbine is reduced to obtain energy-saving benefits; and the other condensed water subjected to heat exchange by the low-temperature economizer 4 enters the sixth low-pressure heater 135 through the second return pipeline 15, so that the heat absorbed by the part of condensed water can be used for exhausting the steam extracted by the sixth low-pressure heater 135 to reduce the heat consumption value of the steam turbine, thereby obtaining energy-saving benefits.

In order to further optimize the technical scheme, the method further comprises the following steps: the system comprises a first temperature sensor, a second temperature sensor, a first electric regulating valve, a second electric regulating valve and a controller;

the first temperature sensor and the second temperature sensor are both connected to the primary air pipe, the first temperature sensor is close to the air inlet end of the temperature-adjusting heat exchange device 7, and the second temperature sensor is close to the air outlet end of the temperature-adjusting heat exchange device 7;

the first electric regulating valve is connected to the condensate water inlet pipeline 11 and is positioned between the temperature-regulating heat exchange device 7 and the low-temperature economizer 4, and the second electric regulating valve is connected to the first reflux pipeline 14;

the controller is electrically connected with the first temperature sensor, the second temperature sensor, the first electric regulating valve and the second electric regulating valve respectively.

By adopting the technical scheme, the temperature of the air inlet end of the temperature-adjusting heat exchange device 7 is detected through the first temperature sensor, temperature information is transmitted to the controller, the temperature of the air outlet end of the temperature-adjusting heat exchange device 7 is detected through the second temperature sensor, and the temperature information is transmitted to the controller, then the controller respectively controls the first electric regulating valve and the second electric regulating valve according to the temperature information detected by the first temperature sensor and the second temperature sensor, so that the temperature of the water inlet end and the water outlet end of the temperature-adjusting heat exchange device 7 can be controlled, the temperature of the air outlet end of the temperature-adjusting heat exchange device 7 can be accurately controlled, and therefore, the air temperature of the inlet of a coal mill is not easy to be higher than a limiting value of the air temperature, and the safety can be improved.

In this application: the temperature of the hot air which is subjected to heat exchange by the air preheater 2 and enters the temperature-regulating heat exchange device 7 is generally higher than 300 ℃, the temperature of the condensation water which is subjected to heat exchange by the low-temperature economizer 4 and enters the temperature-regulating heat exchange device 7 is generally 40-200 ℃, and the heat transfer temperature difference of the temperature-regulating heat exchange device 7 is generally higher than 100 ℃; the inlet smoke temperature of the low-temperature economizer 4 is usually 130-150 ℃, the condensation water temperature of the inlet and the outlet is usually 70-100 ℃, and the heat transfer temperature difference is less than 50 ℃; therefore, the heat transfer efficiency of the temperature-regulating heat exchange device 7 is far higher than that of the common low-temperature economizer 4, the heat exchange area is smaller, and the cost is lower.

In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present utility model. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the utility model. Thus, the present utility model is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (4)

1. A waste heat utilization system for a coal-fired power generation unit, comprising: the flue gas treatment device comprises a flue gas conveying pipeline (1), an air preheater (2), an electric dust collector (3), a low-temperature economizer (4), a primary air blower (5), a primary air pipeline (6), a temperature-adjusting heat exchange device (7), a secondary air pipeline (8), a secondary air blower (9), a warm air blower (10), a condensate water inlet pipeline (11), a first booster pump (12) and a first backflow pipeline (14);

one port of the flue gas conveying pipeline (1) is a flue gas inlet (101) communicated with a flue gas pipeline of a boiler, and the other port is sequentially communicated with an air preheater (2), the low-temperature economizer (4) and the electric dust collector (3);

one end of the primary air pipeline (6) is communicated with the primary air fan (5), and the other end of the primary air pipeline is sequentially communicated with the air preheater (2) and the temperature-regulating heat exchange device (7) and extends out of the temperature-regulating heat exchange device (7) to form a primary air outlet (102);

one end of the secondary air pipeline (8) is communicated with the secondary air blower (9), and the other end of the secondary air pipeline is sequentially communicated with the warm air blower (10) and the air preheater (2) and extends out of the air preheater (2) to form a secondary air outlet (103);

the inlet end of the condensed water inlet pipeline (11) is communicated with the condensed water system (13), the outlet end of the condensed water inlet pipeline (11) is sequentially communicated with the heater (10), the first booster pump (12), the low-temperature economizer (4) and the water inlet end of the temperature-adjusting heat exchange device (7), and the water outlet end of the temperature-adjusting heat exchange device (7) is communicated with the condensed water system (13) through the first backflow pipeline (14).

2. The waste heat utilization system of a coal-fired power unit as defined in claim 1, further comprising: the inlet end of the second backflow pipeline (15) is communicated with the condensate water inlet pipeline (11), the communicated position of the second backflow pipeline (15) and the condensate water inlet pipeline (11) is located between the low-temperature economizer (4) and the temperature-regulating heat exchange device (7) and is close to the low-temperature economizer (4), and meanwhile, the outlet end of the second backflow pipeline (15) is communicated with the condensate water system (13).

3. The waste heat utilization system of a coal-fired power unit according to claim 2, wherein the condensate system (13) comprises: a condensate water conveying pipe (131), a condensate water pump (132), an eighth low-pressure heater (133), a seventh low-pressure heater (134), a sixth low-pressure heater (135), a fifth low-pressure heater (136), a third high-pressure heater (137), a second high-pressure heater (138), a first high-pressure heater (139), a second booster pump (130) and a deaerator (100), wherein the heat of the eighth low-pressure heater (133), the seventh low-pressure heater (134), the sixth low-pressure heater (135), the fifth low-pressure heater (136), the third high-pressure heater (137), the second high-pressure heater (138) and the first high-pressure heater (139) is sequentially increased;

one end of the condensate water conveying pipeline (131) is communicated with the condensate water pump (132), and the other end of the condensate water conveying pipeline is communicated with the eighth low-pressure heater (133), the seventh low-pressure heater (134), the sixth low-pressure heater (135), the fifth low-pressure heater (136), the deaerator (100), the second booster pump (130), the third high-pressure heater (137), the second high-pressure heater (138) and the first high-pressure heater (139) in sequence;

the inlet end of the condensed water inlet pipeline (11), the outlet end of the second backflow pipeline (15) and the outlet end of the first backflow pipeline (14) are connected with the condensed water conveying pipeline (131), the inlet end of the first backflow pipeline (14) is connected with the water outlet end of the temperature-adjusting heat exchange device (7), meanwhile, the inlet end of the condensed water inlet pipeline (11) is close to the outlet end of the seventh low-pressure heater (134), the outlet end of the second backflow pipeline (15) is close to the inlet end of the sixth low-pressure heater (135), and the outlet end of the first backflow pipeline (14) is close to the inlet end of the deaerator (100).

4. A waste heat utilization system for a coal-fired power unit as claimed in any of claims 1-3, further comprising: the system comprises a first temperature sensor, a second temperature sensor, a first electric regulating valve, a second electric regulating valve and a controller;

the first temperature sensor and the second temperature sensor are both connected to the primary air pipe, the first temperature sensor is close to the air inlet end of the temperature-adjusting heat exchange device (7), and the second temperature sensor is close to the air outlet end of the temperature-adjusting heat exchange device (7);

the first electric regulating valve is connected to the condensate water inlet pipeline (11) and is positioned between the temperature-regulating heat exchange device (7) and the low-temperature economizer (4), and the second electric regulating valve is connected to the first backflow pipeline (14);

the controller is electrically connected with the first temperature sensor, the second temperature sensor, the first electric regulating valve and the second electric regulating valve respectively.

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