CN202791972U

CN202791972U - Boiler tail flue gas waste heat utilization system

Info

Publication number: CN202791972U
Application number: CN 201220364143
Authority: CN
Inventors: 陆金琪
Original assignee: Shanghai Apollo Machinery Co Ltd
Current assignee: Shanghai Apollo Machinery Co Ltd
Priority date: 2012-07-25
Filing date: 2012-07-25
Publication date: 2013-03-13
Anticipated expiration: 2022-07-25

Abstract

The utility model discloses a boiler tail flue gas waste heat utilization system capable of improving boiler efficiency by 3%. The boiler tail flue gas waste heat utilization system comprises an air preheater, a dust collector, a draught fan, a flue gas cooler and a desulfurizing tower which are connected sequentially, wherein the air preheater is connected with a flue outlet of a boiler, and the a flue gas outlet of the flue gas cooler is connected with the desulfurizing tower. The flue gas waste heat utilization system further comprises a bypass economizer, two air heaters, a primary fan and a secondary fan, the bypass economizer is connected between the flue outlet of the boiler and an outlet of the air preheater, and the flue gas cooler is an indirectly-heating type heat exchanger, the two air heaters are parallelly connected on a heating medium pipe of the flue gas cooler, the primary fan and the secondary fan are connected at air inlets of the two air heaters respectively, and air outlets of the two heaters are connected with an inlet of the air preheater to enable the boiler flue gas discharge temperature to range from 80 DEG C to 120 DEG C and enable the boiler air inlet temperature to range from 50 DEG C to 80 DEG C.

Description

A kind of boiler tail flue gas bootstrap system

Technical field

The utility model relates to heat power plant boiler tail flue gas UTILIZATION OF VESIDUAL HEAT IN technology, is specifically related to a kind of boiler tail flue gas bootstrap system.

Background technology

At present, the exhaust gas temperature of heat power plant boiler also is to recommend like this on the textbook generally at 120 °～130 ℃ both at home and abroad.The reason of selecting like this is that mainly boiler smoke can produce cold end corrosion to metallic walls when temperature is low, and in order to prevent the generation of cold end corrosion, exhaust gas temperature can not be lower.

The boiler tail flue gas bootstrap system of a representative thermal power plant of Germany, it comprises air preheater, bypass economizer, electric precipitator, air-introduced machine, cold smoke device, wet desulfuration tower, the chimney that is connected with the flue outlet of boiler successively and the formations such as heat medium water preheater that are connected with the heat medium pipe of cold smoke device, this exhaust gas temperature (air preheater outlet cigarette temperature) is 160 ℃, and the EAT of boiler is 120 ℃.

Fig. 1 is the boiler tail flue gas bootstrap system of the higher thermal power plant of the representational efficient of China, it comprises the formations such as the air preheater 1 that is connected with the flue outlet of boiler 1 successively, electric precipitator 4, air-introduced machine 5, low-level (stack-gas) economizer 9, wet desulfuration tower 7, chimney 8, and this exhaust gas temperature (air preheater outlet cigarette temperature) is 125 ℃.

Above-mentioned two kinds of obvious characteristics of systematic comparison are that exhaust gas temperature all is higher than 120 ℃.

Device analysis from the boiler exhaust gas downstream:

Concerning electric precipitator, flue-gas temperature is preferably in about 100 ℃, and efficiency of dust collection is high, does not also have the danger of flue gas low-temperature corrosion;

Concerning air-introduced machine, flue-gas temperature is high 100 ℃ of left and right sides efficient;

Concerning wet desulfuration tower, operating temperature is best 50 ℃ of left and right sides efficient;

From the angle of boiler efficiency, under the prerequisite that the flue gas low-temperature corrosion does not occur, exhaust gas temperature is lower, and efficient is higher.

In sum, efficiently utilize residual heat from boiler fume, further reduce about exhaust gas temperature to 100 ℃ and be conducive to each side.

Usually, the fire coal heat of bringing boiler into is equivalent to heat that boiler main steam and reheated steam takes out of, heat that bypass economizer low-pressure section is taken out of, heat, uncompleted burned carbon heat loss, radiation and heat loss through convection heat loss that boiler exhaust gas is taken out of and does not count heat loss.

Following table is the Efficiency Calculation data of certain 10000MW boiler:

From upper table as seen, the temperature of certain 10000MW boiler air preheater exhanst gas outlet is 128 ℃, and the temperature of boiler air preheater air intlet is 25 ℃, and the boiler exhaust gas heat loss that causes thus is 4.88%, and corresponding boiler thermal output is 94.31%.The minimum metallic walls temperature of the cold junction of the air preheater in this system is about 76 ℃.

Summary of the invention

The purpose of this utility model provides a kind of boiler tail flue gas bootstrap system, the temperature of its energy automatic control boiler smoke evacuation, and significantly dwindled the poor of exhaust gas temperature and EAT, under the prerequisite that has solved the flue gas low-temperature corrosion, the efficient that makes boiler is brought up to more than 96% from present about 94%, realize the efficient utilization of boiler tail flue gas low-temperature heat quantity, reach energy-conservation purpose.

The technical scheme that realizes above-mentioned purpose is: a kind of boiler tail flue gas bootstrap system, comprise the air preheater that is connected with the flue outlet of boiler, the deduster that is connected with air preheater, the air-introduced machine that is connected with deduster, the cold smoke device that is connected with air-introduced machine and the desulfurizing tower that is connected with the exhanst gas outlet of cold smoke device, wherein

Described smoke waste heat utilization system also comprises the bypass economizer between the outlet of the flue outlet that is connected to boiler and air preheater;

Described cold smoke device adopts the indirect-heating heat exchanger that middle heating agent is arranged;

Described smoke waste heat utilization system also comprises two steam air heaters, a primary air fan and an overfire air fan, these two steam air heaters are connected in parallel on the heat medium pipe of described cold smoke device, described primary air fan and overfire air fan are connected to the air inlet of two steam air heaters separately, the air outlet of described two steam air heaters connects the import of described air preheater, and making exhaust gas temperature is 80 ℃～120 ℃ and to make boiler inlet temperature be 50 ℃～80 ℃.

Above-mentioned boiler tail flue gas bootstrap system, wherein, described smoke waste heat utilization system also comprises a hot permanent device of connecting with described two steam air heaters, the heat pipe of the permanent device of this heat connects the low-temperature heat source of steam turbine.

Boiler tail flue gas bootstrap system of the present utility model, adopt the fume afterheat of cold smoke device recovery boiler, and the steam air heater by two parallel connections heats respectively air temperature and the Secondary Air temperature of air preheater import, makes the EAT of air preheater reach 50 ℃～80 ℃; If the fume afterheat that the cold smoke device reclaims can not satisfy two needed heats of steam air heater, just the low-temperature heat source by the permanent device absorption of heat steam turbine satisfies heat balance.Owing to adopt hot permanent device, can automatically improve the heat medium water temperature of cold smoke device, thereby automatically improved the leaving air temp of two steam air heaters, the exhaust gas temperature (air preheater outlet cigarette temperature) of indirectly automatically having controlled boiler is 80 ℃～120 invariable, solved the cold end corrosion of flue gas, on this basis, owing to significantly dwindled the poor of exhaust gas temperature and EAT, so effectively raise boiler efficiency, the efficient that makes boiler is brought up to more than 96% from present about 94%, realized the efficient utilization of boiler tail flue gas low-temperature heat quantity, decrease the net coal consumption rate of unit, have the Social benefit and economic benefit of huge energy-saving and emission-reduction.

Description of drawings

Fig. 1 is the structural representation of the boiler tail flue gas bootstrap system of prior art;

Fig. 2 is the structural representation of boiler tail flue gas bootstrap system of the present utility model.

The specific embodiment

In order to make those skilled in the art can understand better the technical solution of the utility model, below in conjunction with accompanying drawing its specific embodiment is described in detail:

See also Fig. 2, a kind of boiler tail flue gas bootstrap system of the present utility model, comprise the bypass economizer 3 between the outlet of the air preheater 2 that is connected with the flue outlet of boiler 1, the deduster 4 that is connected with air preheater 2, the air-introduced machine 5 that is connected with deduster 4, the cold smoke device 6 that is connected with air-introduced machine 5, the desulfurizing tower 7 that is connected with the exhanst gas outlet of cold smoke device 6, the chimney 8 that is connected with desulfurizing tower 7 and the exhanst gas outlet that is connected to boiler 1 and air preheater 2, also comprise two steam air heaters 61,62, primary air fan 63, overfire air fan 64 and hot permanent device 65, wherein:

Cold smoke device 6 adopts the indirect-heating heat exchanger that middle heating agent is arranged, and middle heating agent adopts water;

Two steam air heaters 61,62 are connected in parallel on the heat medium pipe of cold smoke device 6, and primary air fan 63 and overfire air fan 64 are connected to two steam air heaters 61,62 air inlet separately, and two steam air heaters 61,62 air outlet connect the import of air preheater 2;

The permanent device 65 of heat is connected on the heat medium pipe of cold smoke device 6 with two steam air heaters 61,62, the low-temperature heat source 10 of the heat pipe connection steam turbine of the permanent device 65 of this heat.

The operation principle of a kind of boiler tail flue gas bootstrap system of the present utility model is: the flue gas in the boiler 1 enters deduster 4 by flue after air preheater 2 and bypass economizer 3 make exhaust gas temperature (the cigarette actuator temperature of air preheater outlet) cool to 80 ℃～120 ℃, flue gas after deduster 4 dedustings enters 6 coolings of cold smoke device again after air-introduced machine 5 boosts, make flue gas be cooled to enter about 85 ℃ desulfurizing tower 7 desulfurization, then emptying through chimney 8; Cold smoke device 6 liberated heat in the process of cooled flue gas enters air preheater 2 by heat medium water heat-carrying to two steam air heater 61,62 and by wind of primary air fan 63 heating boilers and overfire air fan 64 heating boiler Secondary Airs respectively after the temperature of the temperature of a wind and Secondary Air brought up to 50 ℃～80 ℃.When environment temperature reduces or during the load reduction of Steam Turbine, when cold smoke device 6 liberated heats are not enough to that wind and Secondary Air temperature brought up to 80 ℃～120 ℃ of control exhaust gas temperatures, enter the heat medium water temperature that hot permanent device 65 improves cold smoke device 6 with regard to the low-temperature heat source that needs steam turbine, thereby automatically improved two steam air heaters 61,62 leaving air temp, indirectly automatically to have controlled exhaust gas temperature invariable.

After the system of utility model brings up to the EAT of air preheater 2 about 60 ℃, the exhaust gas temperature that makes in conjunction with bypass economizer 3 is 100 ℃, the cold junction minimum temperature of the metallic walls of air preheater 2 is about 80 ℃ like this, about 75 ℃ of cold junction minimum temperatures that are higher than the metallic walls of the general air preheater of existing domestic and international boiler are so at first solved heated surface at the end of boiler flue gas low-temperature etching problem.

In the boiler heat loss, heat loss due to exhaust gas is maximum one, almost has about 5%.The size of heat loss due to exhaust gas depends on the poor of exhaust gas temperature and EAT.The system of utility model is owing to significantly dwindled the poor of exhaust gas temperature and EAT, so effectively raise boiler efficiency, realized the efficient utilization of boiler tail flue gas low-temperature heat quantity, realized the efficient utilization of boiler tail flue gas low-temperature heat quantity, decrease the net coal consumption rate of unit, have the Social benefit and economic benefit of huge energy-saving and emission-reduction.

Certainly, because bypass economizer 3 is all relevant with thermodynamic system of steam tur with hot permanent device 65.Wherein bypass economizer 3 will reduce drawing gas of extracted steam from turbine heat regenerative system, the permanent device 65 of heat will increase steam turbine low-pressure the drawing gas of heat regenerative system of drawing gas, this two aspect all will cause the variation of thermal loss of steam turbine, but this raising that changes relative boiler efficiency is much smaller on the impact of unit net coal consumption rate, so totally will reduce more than the unit net coal consumption rate 6g/kWh.

Those of ordinary skill in the art will be appreciated that, above embodiment illustrates the utility model, and be not to be used as restriction of the present utility model, as long as in connotation scope of the present utility model, all will drop in claims scope of the present utility model variation, the modification of the above embodiment.

Claims

1. boiler tail flue gas bootstrap system, comprise the air preheater that is connected with the flue outlet of boiler, the deduster that is connected with air preheater, the air-introduced machine that is connected with deduster, the cold smoke device that is connected with air-introduced machine and the desulfurizing tower that is connected with the exhanst gas outlet of cold smoke device, it is characterized in that

2. boiler tail flue gas bootstrap system according to claim 1 is characterized in that, described smoke waste heat utilization system also comprises a hot permanent device of connecting with described two steam air heaters, and the heat pipe of the permanent device of this heat connects the low-temperature heat source of steam turbine.