CN111981465A - Flue gas waste heat utilization system - Google Patents

Flue gas waste heat utilization system Download PDF

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Publication number
CN111981465A
CN111981465A CN202010960827.2A CN202010960827A CN111981465A CN 111981465 A CN111981465 A CN 111981465A CN 202010960827 A CN202010960827 A CN 202010960827A CN 111981465 A CN111981465 A CN 111981465A
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CN
China
Prior art keywords
flue gas
heater
condensed water
waste heat
temperature section
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202010960827.2A
Other languages
Chinese (zh)
Inventor
张美凤
贾明华
王大志
韩威
孙贻超
季勇
潘振艳
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Yantai Longyuan Power Technology Co Ltd
Original Assignee
Yantai Longyuan Power Technology Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Yantai Longyuan Power Technology Co Ltd filed Critical Yantai Longyuan Power Technology Co Ltd
Priority to CN202010960827.2A priority Critical patent/CN111981465A/en
Publication of CN111981465A publication Critical patent/CN111981465A/en
Pending legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22STEAM GENERATION
    • F22DPREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
    • F22D1/00Feed-water heaters, i.e. economisers or like preheaters
    • F22D1/50Feed-water heaters, i.e. economisers or like preheaters incorporating thermal de-aeration of feed-water
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23JREMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J15/00Arrangements of devices for treating smoke or fumes
    • F23J15/06Arrangements of devices for treating smoke or fumes of coolers
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23LSUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
    • F23L15/00Heating of air supplied for combustion
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H3/00Air heaters
    • F24H3/02Air heaters with forced circulation
    • F24H3/06Air heaters with forced circulation the air being kept separate from the heating medium, e.g. using forced circulation of air over radiators
    • F24H3/08Air heaters with forced circulation the air being kept separate from the heating medium, e.g. using forced circulation of air over radiators by tubes
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H9/00Details
    • F24H9/12Arrangements for connecting heaters to circulation pipes
    • F24H9/13Arrangements for connecting heaters to circulation pipes for water heaters
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H9/00Details
    • F24H9/18Arrangement or mounting of grates or heating means
    • F24H9/1809Arrangement or mounting of grates or heating means for water heaters
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H9/00Details
    • F24H9/18Arrangement or mounting of grates or heating means
    • F24H9/1854Arrangement or mounting of grates or heating means for air heaters
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D7/00Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00Combustion technologies with mitigation potential
    • Y02E20/34Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery

Abstract

The invention discloses a flue gas waste heat utilization system, which belongs to the field of energy conservation and emission reduction of thermal power generating units, wherein an economizer of the flue gas waste heat utilization system is respectively communicated with an air preheater and a bypass flue, and an outlet of the air preheater and the tail end of the bypass flue are communicated with a high-temperature section flue gas heat exchanger; a feed water heater and a condensed water heater are arranged in the bypass flue in series, the feed water heater is connected in parallel with the pipeline of the high-pressure heater, and the condensed water heater and the high-temperature section flue gas heat exchanger are connected in parallel with the pipeline of the low-pressure heater; a low-temperature section flue gas heat exchanger is arranged between the high-temperature section flue gas heat exchanger and the flue gas treatment device, a secondary air heater is arranged between the air feeder and the air preheater, a primary air heater is arranged between the primary air fan and the air preheater, and a circulating water system is arranged between the low-temperature section flue gas heat exchanger, the secondary air heater and the primary air heater. The flue gas waste heat utilization system realizes cascade utilization of flue gas waste heat of the boiler, and avoids the defect that the air preheater occupies too large area and is difficult to arrange.

Description

Flue gas waste heat utilization system
Technical Field
The invention relates to the technical field of energy conservation and emission reduction of thermal power generating units, in particular to a flue gas waste heat utilization system.
Background
In the thermal power plant in China, 70-80% of the total heat loss of the boiler is the heat loss of the exhaust smoke. When the exhaust gas temperature rises by 10-15 ℃, the boiler efficiency is reduced by 1%, and the annual average standard coal consumption rises by 3-4 g/(kW.h). Along with the stricter policy of energy conservation and emission reduction and the continuous rising of energy price, the importance of reasonably utilizing the waste heat of the boiler flue gas is increasing.
The most common mode in the traditional flue gas waste heat utilization modes is that a low-temperature economizer is arranged in a tail flue behind an air preheater, and the flue gas waste heat is utilized to heat condensed water in a regenerative system so as to reduce the steam extraction amount of the regenerative system; the saved extracted steam enters a subsequent steam turbine to continue to expand to work, and the total work output of the steam turbine is increased, so that the economy of the whole unit is improved.
The flue gas waste heat utilization scheme mainly has the defects that the flue gas waste heat cannot be utilized in a gradient manner, the waste heat utilization rate is low, and the energy is wasted.
Therefore, it is necessary to provide a flue gas waste heat utilization system to solve the above technical problems in the prior art.
Disclosure of Invention
The invention aims to provide a flue gas waste heat utilization system which can realize gradient utilization of flue gas waste heat and is high in energy utilization rate.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a kind of waste heat utilization system of flue gas, its boiler flue arranges coal economizer and air preheater in proper order, the said waste heat utilization system of flue gas also includes the feed water heater, condensed water heater, high-temperature section flue gas heat exchanger, low-pressure heater group, high-pressure heater group, blower, primary air heater, secondary air heater and flue gas processing unit;
the low-pressure heater group comprises a plurality of low-pressure heaters which are sequentially communicated through low-pressure heater pipelines; the high-pressure heater group comprises a plurality of high-pressure heaters which are sequentially communicated through high-pressure heater pipelines; condensed water passes through the low-pressure heaters and the high-pressure heaters in sequence and then is introduced into the economizer;
the flue gas outlet of the economizer is respectively communicated with the air preheater and a bypass flue of the air preheater, and the outlet of the air preheater and the tail end of the bypass flue are converged and communicated to a flue gas inlet of the high-temperature section flue gas heat exchanger;
the feed water heater and the condensed water heater are arranged in the bypass flue in series, the feed water heater is connected in parallel in the high-pressure heater pipeline, and the condensed water heater and the high-temperature section flue gas heat exchanger are connected in parallel in the low-pressure heater pipeline;
the high temperature section gas heater with be provided with between the gas processing apparatus low temperature section gas heater, the forced draught blower with the primary air fan all with air heater intercommunication, the forced draught blower with be provided with between the air heater secondary air fan heater, the primary air fan with be provided with between the air heater primary air fan heater, low temperature section gas heater secondary air fan heater with set up circulating water system between the primary air fan heater.
As an optimal technical scheme of the above flue gas waste heat utilization system, the flue gas waste heat utilization system further includes:
and the bypass flue adjusting valve is arranged in the bypass flue and is used for adjusting the flue gas volume in the bypass flue.
As an optimal technical scheme of the above flue gas waste heat utilization system, the flue gas waste heat utilization system further includes:
the water inlet end of the condensed water inlet pipeline is communicated with the low-pressure heater pipeline, and the water outlet end of the condensed water inlet pipeline is respectively communicated with the condensed water heater and the high-temperature section flue gas heat exchanger;
and the condensed water inlet regulating valve is arranged in the condensed water inlet pipeline.
As an optimal technical scheme of the above flue gas waste heat utilization system, the flue gas waste heat utilization system further includes:
the condensed water variable-frequency circulating pump is arranged in the condensed water inlet pipeline, and the condensed water at the outlet of the condensed water variable-frequency circulating pump flows into the condensed water heater and the high-temperature section flue gas heat exchanger respectively;
and the condensate water parallel connection adjusting valve is arranged in a pipeline between the condensate water variable-frequency circulating pump and the condensate water heater or a pipeline between the condensate water variable-frequency circulating pump and the high-temperature section flue gas heat exchanger.
As an optimal technical scheme of the above flue gas waste heat utilization system, the flue gas waste heat utilization system further includes:
the water inlet end of the water supply and inlet pipeline is communicated with the high-pressure heater pipeline, and the water outlet end of the water supply and inlet pipeline is communicated with the water supply heater;
and the water feeding and inlet adjusting valve is arranged in the water feeding and inlet pipeline.
As an optimal technical scheme of the above flue gas waste heat utilization system, the flue gas waste heat utilization system further includes:
and the deaerator is arranged between the low-pressure heater group and the high-pressure heater group.
As the preferable technical scheme of the flue gas waste heat utilization system, the outlet flue gas temperature of the high-temperature section flue gas heat exchanger is 90-100 ℃, and the flue gas resistance is 100-800 Pa.
As the preferable technical scheme of the flue gas waste heat utilization system, the outlet flue gas temperature of the low-temperature section flue gas heat exchanger is 75-85 ℃, and the flue gas resistance is 100Pa-800 Pa.
As the preferable technical scheme of the flue gas waste heat utilization system, the outlet air temperature of the primary air heater and the outlet air temperature of the secondary air heater are 50-90 ℃, and the air resistance is 100-800 Pa.
As the preferable technical scheme of the flue gas waste heat utilization system, the flue gas amount in the bypass flue is 10% -30% of the total outlet flue gas amount of the air preheater.
Compared with the prior art, the invention has the beneficial effects that:
compared with a conventional power station boiler system, the flue gas waste heat utilization system realizes the stepped effective utilization of the flue gas waste heat of the boiler, improves the heat efficiency of the boiler and realizes the efficient utilization of energy; simultaneously, this flue gas waste heat utilization system can also avoid the too big drawback that is difficult to arrange of air heater area that leads to when the hot-blast of conventional recovery system of discharging fume heats.
Drawings
Fig. 1 is a schematic diagram of a flue gas waste heat utilization system according to an embodiment of the present invention.
In the figure:
1. a coal economizer; 2. an air preheater; 3. a feedwater heater; 4. a condensed water heater; 5. a high temperature section flue gas heat exchanger; 6. a low temperature section flue gas heat exchanger; 7. a blower; 8. a primary air fan; 9. a primary air heater; 10. a secondary air heater; 11. a flue gas treatment device; 12. a bypass flue regulating valve; 13. a condensed water inlet regulating valve; 14. a condensed water variable frequency circulating pump; 15. the condensed water is connected with the regulating valve in parallel; 16. a feed water inlet regulating valve; 17. a deaerator; 18. a first low pressure heater; 19. a second low pressure heater; 20. a third low pressure heater; 21. a fourth low pressure heater; 22. a first high pressure heater; 23. a second high pressure heater; 24. a third high pressure heater; 25. a booster pump; 26. the low-temperature section flue gas heat exchanger is connected with the regulating valve in parallel; 27. an electrostatic precipitator; 28. an induced draft fan.
Detailed Description
In order to make the technical problems solved, the technical solutions adopted and the technical effects achieved by the present invention clearer, the technical solutions of the present invention are further described below by way of specific embodiments with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some but not all of the elements associated with the present invention are shown in the drawings.
In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.
In the description of the present embodiment, the terms "upper", "lower", "left", "right", and the like are used based on the orientations and positional relationships shown in the drawings only for convenience of description and simplification of operation, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used only for descriptive purposes and are not intended to have a special meaning.
Compared with a conventional power station boiler system, the flue gas waste heat utilization system realizes the cascade effective utilization of the flue gas waste heat of the boiler, can effectively reduce the coal consumption of a coal-fired generating set, improves the boiler efficiency and realizes the efficient utilization of energy. Meanwhile, the flue gas waste heat utilization system can also avoid the defect that the conventional recovery smoke exhaust system is difficult to arrange due to overlarge occupied area of the air preheater 2 when heating hot air.
As shown in fig. 1, the flue gas waste heat utilization system mainly includes an economizer 1, an air preheater 2, a feed water heater 3, a condensed water heater 4, a high-temperature section flue gas heat exchanger 5, a low-temperature section flue gas heat exchanger 6, a low-pressure heater group, a high-pressure heater group, a blower 7, a primary fan 8, a primary air heater 9, a secondary air heater 10 and a flue gas treatment device 11.
The economizer 1 and the air preheater 2 are sequentially arranged in a boiler flue of the flue gas waste heat utilization system, a flue gas outlet of the economizer 1 is respectively communicated with bypass flues of the air preheater 2 and the air preheater 2, a feed water heater 3 and a condensed water heater 4 are arranged in the bypass flues in series, one part of flue gas enters the air preheater 2 to heat air, and the other part of flue gas enters the bypass flues and sequentially flows through the feed water heater 3 and the condensed water heater 4 to respectively heat feed water and condensed water. The outlet of the air preheater 2 and the tail end of the bypass flue are converged and communicated to the flue gas inlet of the high-temperature section flue gas heat exchanger 5, and flue gas after heat exchange respectively is converged in front of the high-temperature section flue gas heat exchanger 5. Optionally, a bypass flue adjusting valve 12 is arranged in the bypass flue and used for adjusting the amount of flue gas in the bypass flue, so as to adjust the ratio of the amount of flue gas entering the air preheater 2 to the amount of flue gas in the bypass flue. Preferably, the amount of flue gas in the bypass flue in the embodiment is 10% -30% of the total amount of flue gas at the outlet of the air preheater 2.
The low-pressure heater group comprises a plurality of low-pressure heaters which are sequentially communicated through low-pressure heater pipelines. The inlet end of the lp heater line (shown as a in fig. 1) is connected to an external source of condensed water (not shown), and the outlet end of the lp heater line is connected to the hp heater bank. Optionally, the low pressure heater group comprises four low pressure heaters, namely a first low pressure heater 18, a second low pressure heater 19, a third low pressure heater 20 and a fourth low pressure heater 21, along the direction from the water inlet end to the water outlet end of the low pressure heater pipeline, the inlet of the first low pressure heater 18 is communicated with the condensed water source, and the outlet of the fourth low pressure heater 21 is communicated with the high pressure heater group. It is understood that the number of the low pressure heaters included in the low pressure heater group can be designed according to actual working conditions.
The high-pressure heater group comprises a plurality of high-pressure heaters which are sequentially communicated through high-pressure heater pipelines. The water inlet end of the high-pressure heater pipeline is communicated with the water outlet end of the low-pressure heater pipeline, and the water outlet end of the high-pressure heater pipeline is communicated with the economizer 1. Optionally, the high-pressure heater group includes three high-pressure heaters, namely a first high-pressure heater 22, a second high-pressure heater 23 and a third high-pressure heater 24, along a direction from the water inlet end to the water outlet end of the high-pressure heater pipeline, an inlet of the first high-pressure heater 22 is communicated with the water outlet end of the low-pressure heater pipeline, and an outlet of the third high-pressure heater 24 is communicated with the economizer 1. It is understood that the number of the high pressure heaters included in the high pressure heater group can be designed according to actual working conditions.
Preferably, a deaerator 17 is provided between the low pressure heater group and the high pressure heater group. The low-pressure heater group, the high-pressure heater group and the deaerator 17 jointly form a heat regeneration system of the flue gas waste heat utilization system, and condensed water passes through the heat regeneration system and then is introduced into the economizer 1.
The feed water heater 3 is connected in parallel with the water inlet end and the water outlet end of the high-pressure heater pipeline through a feed water inlet pipeline and a feed water outlet pipeline, and feed water flows through the feed water heater 3 to return to the water outlet end of the high-pressure heater pipeline after absorbing the heat of the flue gas. Preferably, a feed water inlet regulating valve 16 is arranged in the feed water inlet pipeline and used for regulating the feed water flow flowing into the feed water heater 3 and ensuring that the feed water return temperature meets the outlet water temperature requirement of the third high-pressure heater 24.
The condensed water heater 4 and the high-temperature section flue gas heat exchanger 5 are connected in parallel in the low-pressure heater pipeline, part of the condensed water flows through the condensed water heater 4 to absorb heat and then returns to the low-pressure heater pipeline, and the other part of the condensed water flows through the high-temperature section flue gas heat exchanger 5 to absorb heat and then returns to the low-pressure heater pipeline.
Specifically, the flue gas waste heat utilization system further comprises a condensed water inlet pipeline and a condensed water return pipeline. Wherein, the water inlet end of the condensed water inlet pipeline is communicated with the low-pressure heater pipeline, and the water outlet end of the condensed water inlet pipeline is respectively communicated with the condensed water heater 4 and the high-temperature section flue gas heat exchanger 5. More specifically, the condensate water inlet pipeline includes two branch road of intaking, be first branch road of intaking and second branch road of intaking respectively, wherein, first branch road of intaking communicates in the inlet pipeline department of first low pressure feed water heater 18, the branch road of intaking of second communicates in the outlet pipeline department of second low pressure feed water heater 19, under this structure for the condensate water of two different temperatures gets into the condensate water inlet pipeline after mixing, guarantees that the temperature of mixing the condensate water satisfies the entry temperature requirement of condensate water heater 4, and guarantees that high temperature section gas heater 5's pipe wall does not take place low temperature corrosion. It will be appreciated that the number of water inlet branches and the location of the connections on the lp heater line may be designed according to the actual operating conditions. The water outlet end of the condensed water return pipeline is communicated with the outlet pipeline of the third low-pressure heater 20.
In order to prevent the low-temperature corrosion of the condensed water heater 4 and the high-temperature section flue gas heat exchanger 5, the flue gas waste heat utilization system further comprises a condensed water inlet regulating valve 13, and the condensed water inlet regulating valve 13 is arranged in the first water inlet branch or the second water inlet branch. The proportion of the flow of the condensate in the first water inlet branch and the flow of the condensate in the second water inlet branch is adjusted by regulating the opening degree of the condensate water inlet regulating valve 13, so that the automatic control of the temperature of the condensate water entering the condensate water heater 4 and the high-temperature section flue gas heat exchanger 5 is realized. Optionally, the temperature of the condensed water is designed to be 65-80 ℃. The condensate inlet regulating valve 13 in this embodiment is preferably arranged in the first inlet branch.
For preventing that condensate pump (not shown in the figure) pressure head is not enough to cause circulating power not enough, this flue gas waste heat utilization system still includes condensate frequency conversion circulating pump 14, and condensate frequency conversion circulating pump 14 sets up in the condensate water inlet pipe, and condensate frequency conversion circulating pump 14 provides power for whole condensate system. Condensed water at the outlet of the condensed water variable-frequency circulating pump 14 is divided into two paths, one path of condensed water enters the condensed water heater 4 to absorb high-quality heat of the flue gas, the other path of condensed water enters the high-temperature section flue gas heat exchanger 5 to absorb waste heat of the flue gas, and condensed water return water of the condensed water and the condensed water return water returns to an outlet pipeline of the third low-pressure heater 20 through a condensed water return pipeline.
Further, the flue gas waste heat utilization system further comprises a condensate parallel regulating valve 15, and the condensate parallel regulating valve 15 is arranged in a pipeline between the condensate variable-frequency circulating pump 14 and the condensate heater 4 or a pipeline between the condensate variable-frequency circulating pump 14 and the high-temperature section flue gas heat exchanger 5. The former is preferred in this embodiment.
The flow entering the condensate water heater 4 and the high-temperature section flue gas heat exchanger 5 is jointly adjusted through the condensate water parallel adjusting valve 15 and the condensate water variable-frequency circulating pump 14, on one hand, the return water temperature of the condensate water is guaranteed to meet the requirement of the outlet water temperature of the third low-pressure heater 20, on the other hand, the outlet smoke temperature of the high-temperature section flue gas heat exchanger 5 is guaranteed to meet the operation requirement, under the condition of preventing summer or high load, the exhaust smoke temperature is increased, a large amount of flue gas waste heat is recycled by the low-temperature section flue gas heat exchanger 6, and the outlet air temperature of the primary air heater 9 and the secondary air.
Particularly, be provided with low temperature section gas heater 6 between high temperature section gas heater 5 and the flue gas processing apparatus 11, forced draught blower 7 and primary air fan 8 all communicate with air heater 2, be provided with overgrate air fan heater 10 between forced draught blower 7 and the air heater 2, be provided with primary air fan heater 9 between primary air fan 8 and the air heater 2, low temperature section gas heater 6, set up circulating water system between overgrate air fan heater 10 and the primary air fan heater 9, realize utilizing the purpose of flue gas heat heated air, the cold wind temperature that gets into air heater 2 has been improved, the high-quality steam extraction volume of the original fan heater system of power plant has been reduced, thereby reduce the electricity generation coal consumption of unit. Optionally, a booster pump 25 and a low-temperature section flue gas heat exchanger parallel regulating valve 26 are arranged in the circulating water system, power of circulating water is provided by the booster pump 25, and the low-temperature section flue gas heat exchanger parallel regulating valve 26 is used for regulating water amount entering the primary air heater 9 and the secondary air heater 10.
The flue gas treatment device 11 in this embodiment is a desulfurizing tower, an electrostatic dust collector 27 and an induced draft fan 28 are further arranged between the flue gas outlet of the high-temperature section flue gas heat exchanger 5 and the desulfurizing tower, and optionally, the low-temperature section flue gas heat exchanger 6 is arranged in a flue between the induced draft fan 28 and the desulfurizing tower.
It should be noted that the structures of the economizer 1, the air preheater 2, the electrostatic precipitator 27, the desulfurizing tower and the like in the present embodiment are conventional structures in the prior art, and the present embodiment does not specifically describe the specific structures and the working principles thereof.
In this embodiment, the flue gas heat exchanger 5 at the high temperature section is a fin-tube type steam-water heat exchanger arranged in a countercurrent manner. The outlet flue gas temperature of the high-temperature section flue gas heat exchanger 5 is designed to be 90-100 ℃, and the flue gas resistance is designed to be 100-800 Pa.
The low-temperature section flue gas heat exchanger 6 is a fluoroplastic or PPS plastic alloy tubular heat exchanger arranged in a countercurrent mode. The outlet flue gas temperature of the low-temperature section flue gas heat exchanger 6 is designed to be 75-85 ℃, and the flue gas resistance is designed to be 100Pa-800 Pa.
The primary air heater 9 and the secondary air heater 10 are both spiral fin tube heat exchangers arranged in a countercurrent mode. The air temperature at the outlet of the primary air heater 9 and the secondary air heater 10 is designed to be 50-90 ℃, and the air resistance is designed to be 100-800 Pa.
The foregoing embodiments are merely illustrative of the principles and features of this invention, which is not limited to the above-described embodiments, but rather is susceptible to various changes and modifications without departing from the spirit and scope of the invention, which changes and modifications are within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (10)

1. A flue gas waste heat utilization system is characterized in that a coal economizer (1) and an air preheater (2) are sequentially arranged in a boiler flue of the flue gas waste heat utilization system, and the flue gas waste heat utilization system further comprises a feed water heater (3), a condensed water heater (4), a high-temperature section flue gas heat exchanger (5), a low-temperature section flue gas heat exchanger (6), a low-pressure heater group, a high-pressure heater group, a blower (7), a primary fan (8), a primary air heater (9), a secondary air heater (10) and a flue gas treatment device (11);
the low-pressure heater group comprises a plurality of low-pressure heaters which are sequentially communicated through low-pressure heater pipelines; the high-pressure heater group comprises a plurality of high-pressure heaters which are sequentially communicated through high-pressure heater pipelines; condensed water passes through the low-pressure heaters and the high-pressure heaters in sequence and then is introduced into the economizer (1);
a flue gas outlet of the economizer (1) is respectively communicated with the air preheater (2) and a bypass flue of the air preheater (2), and an outlet of the air preheater (2) and the tail end of the bypass flue are converged and communicated to a flue gas inlet of the high-temperature section flue gas heat exchanger (5);
the feed water heater (3) and the condensed water heater (4) are arranged in the bypass flue in series, the feed water heater (3) is connected in parallel in the high-pressure heater pipeline, and the condensed water heater (4) and the high-temperature section flue gas heat exchanger (5) are connected in parallel in the low-pressure heater pipeline;
high temperature section gas heater (5) with be provided with between flue gas processing apparatus (11) low temperature section gas heater (6), forced draught blower (7) with primary air fan (8) all with air heater (2) intercommunication, forced draught blower (7) with be provided with between air heater (2) overgrate air fan heater (10), primary air fan (8) with be provided with between air heater (2) primary air fan heater (9), low temperature section gas heater (6) overgrate air fan heater (10) with set up circulating water system between primary air fan heater (9).
2. The flue gas waste heat utilization system according to claim 1, further comprising:
and the bypass flue adjusting valve (12) is arranged in the bypass flue and is used for adjusting the amount of flue gas in the bypass flue.
3. The flue gas waste heat utilization system according to claim 1, further comprising:
the water inlet end of the condensed water inlet pipeline is communicated with the low-pressure heater pipeline, and the water outlet end of the condensed water inlet pipeline is respectively communicated with the condensed water heater (4) and the high-temperature section flue gas heat exchanger (5);
and the condensed water inlet regulating valve (13) is arranged in the condensed water inlet pipeline.
4. The flue gas waste heat utilization system according to claim 3, further comprising:
the condensed water variable-frequency circulating pump (14) is arranged in the condensed water inlet pipeline, and the condensed water at the outlet of the condensed water variable-frequency circulating pump (14) flows into the condensed water heater (4) and the high-temperature section flue gas heat exchanger (5) respectively;
and the condensed water parallel regulating valve (15) is arranged in a pipeline between the condensed water variable-frequency circulating pump (14) and the condensed water heater (4) or in a pipeline between the condensed water variable-frequency circulating pump (14) and the high-temperature section flue gas heat exchanger (5).
5. The flue gas waste heat utilization system according to claim 1, further comprising:
the water inlet end of the water supply and inlet pipeline is communicated with the high-pressure heater pipeline, and the water outlet end of the water supply and inlet pipeline is communicated with the water supply heater (3);
and the water feeding and inlet adjusting valve (16) is arranged in the water feeding and inlet pipeline.
6. The flue gas waste heat utilization system according to claim 1, further comprising:
and the deaerator (17) is arranged between the low-pressure heater group and the high-pressure heater group.
7. The flue gas waste heat utilization system according to claim 1,
the outlet flue gas temperature of the high-temperature section flue gas heat exchanger (5) is 90-100 ℃, and the flue gas resistance is 100-800 Pa.
8. The flue gas waste heat utilization system according to claim 1,
the outlet flue gas temperature of the low-temperature section flue gas heat exchanger (6) is 75-85 ℃, and the flue gas resistance is 100Pa-800 Pa.
9. The flue gas waste heat utilization system according to claim 1,
the air temperature at the outlet of the primary air heater (9) and the secondary air heater (10) is 50-90 ℃, and the air resistance is 100-800 Pa.
10. The flue gas waste heat utilization system according to claim 1,
the smoke amount in the bypass flue is 10% -30% of the total smoke amount at the outlet of the air preheater (2).
CN202010960827.2A 2020-09-14 2020-09-14 Flue gas waste heat utilization system Pending CN111981465A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112503556A (en) * 2020-12-02 2021-03-16 大唐环境产业集团股份有限公司 Flue gas waste heat recovery device of thermal power generating unit boiler

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112503556A (en) * 2020-12-02 2021-03-16 大唐环境产业集团股份有限公司 Flue gas waste heat recovery device of thermal power generating unit boiler

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