A kind of boiler smoke degree of depth cooling residual heat retracting device
Technical field
The utility model belongs to the heat recovery technical field, is specifically related to the flue gas degree of depth cooling residual heat recycle device of a kind of station boiler, Industrial Boiler.
Background technology
Heat loss due to exhaust gas is one maximum in the every heat loss of boiler, generally 5%~12%, account for the total heat loss of boiler 80% or higher.For recycling the boiler exhaust gas waste heat, mainly taked following two kinds of forms at different units:
1) for traditional coal-fired unit that is not equipped with desulphurization system, prior art is installed low-pressure coal saver usually between the air preheater of boiler and electrostatic precipitator, utilize the condensate water of fume afterheat heating heat regenerative system, return low-pressure heater after the condensate water heat absorption, low pressure (LP) cylinder utilizes this part flue gas heat to drive generator for electricity generation then, has produced huge economic benefit.But, fly ash content is very high between air preheater and the electrostatic precipitator, efficiency of dust collection calculates according to 99.4%~99.6%, flue gas flying dust concentration approximately differs from 400~600 times before and after the electrostatic precipitator, must cause the heavy wear of pipeline heating surface, heat exchanger tube shortening in service life, the safety coefficient of equipment reduces.For this reason, need be in a reasonable range with the wear control of pipeline, and flying dust is directly proportional with 3 powers of flue gas flow rate to the rate of wear of tube wall, the control wearing and tearing will be controlled flue gas flow rate.Usually, the heat exchange area by increasing low-pressure coal saver reaches the purpose of restriction flue gas flow rate, but has increased equipment investment cost to increase flue gas resistance.
Simultaneously, for fear of cold end corrosion occurring, low-pressure coal saver inlet tube wall temperature is controlled on the flue gas acid dew point, and the temperature control of outlet cigarette is at 130 ℃~150 ℃, and the recovery of heat is subjected to serious restriction.And the temperature of flue gas behind low-pressure coal saver descends, and flue dust raises more than resistance, and this performance and life-span to electrostatic precipitator can have a significant impact, and efficiency of dust collection obviously descends.Even guaranteeing flue-gas temperature maintains more than the acid dew-point temperature, also can't thoroughly avoid the possibility of smoke condensation, the moisture of the raw coal water content that for example causes rainy season during increase can cause discharging fume greatly significantly rises, and perhaps occurs the dewfall phenomenon that booster situation etc. all can cause the low-pressure coal saver tube wall during boiler operatiopn.In case dewfall, calcareous in the flying dust will combine with acid in the flue gas and moisture and form cement-like material and be deposited on and be difficult on the tube wall remove.Time one is long, and these cement-like materials are easy to stop up pipe row, and this brings serious hidden danger for the safe operation of unit.Stop up in a single day and take place, exhaust gases passes will reduce, and circulating resistance increases, and station service rises.Can cause unit to fall when serious to exert oneself even by forced-stopping machine.In addition, be in the preceding low-level (stack-gas) economizer of quiet deduster, easily frayed and corrosion, in case pipe perforation is revealed, the condensate water of ejection can become the disaster of electrostatic precipitator or fiber bag precipitator.
2) the supporting coal-fired unit of desulphurization system can be installed the waste heat that gas-gas heat exchanger (GGH) flue gas reheat device reclaims flue gas usually in desulphurization system, be energy savings, is installed in before the desulfurizing tower usually.
In general, the best desulfurization operating temperature of boiler smoke wet desulphurization is 80~90 ℃.For this reason, just feed after utilizing GGH to drop to 130 ℃~150 ℃ exhaust gas temperature about 90 ℃ and carry out desulfurization in the desulfurizing tower, temperature drops to about 50 ℃ after the desulfurization.In order to improve atmosphere hoist height, avoid desulfurizing tower outlet low temperature wet flue gas corrosion flue and inner wall of stack, utilize gas-gas heat exchanger (GGH) that desulfurizing tower is exported clean flue gas again and be heated to 80 ℃~100 ℃ from about 50 ℃, at last by smoke stack emission.As seen, install gas-gas heat exchanger (GGH) additional and can not bring remarkable economic efficiency, the fume afterheat of degree is wasted in vain more than 100, and gas-gas heat exchanger (GGH) complex structure, operational reliability are low, the installment work cycle is longer, the initial investment of equipment is bigger, and gas-gas heat exchanger (GGH) can not generally be promoted the use of.
Development and people's going deep into along with desulfur technology to gas-gas heat exchanger (GGH) effect understanding, find the effectiveness that gas-gas heat exchanger (GGH) does not have increases environmental protection, even it is still not high to have adorned gas-gas heat exchanger (GGH) flue-gas temperature, flue and inner wall of stack still need be taked anti-corrosion measure, and do not increase atmosphere pollution if the phenomenon that presents a large amount of water spray hazes in the chimney emission that gas-gas heat exchanger (GGH) causes is not installed.Therefore, developed country and area tend to not establish gas-gas heat exchanger (GGH) gradually now, and the newly-built desulfurizing item of China recent years also begins to accept not adorn the design of gas-gas heat exchanger (GGH).
In view of this, how under the prerequisite that gas-gas heat exchanger (GGH) is not set, reclaim fume afterheat, reduce the corrosion of desulfurizing tower rear pass and chimney, become the technical problem that needs to be resolved hurrily.
Summary of the invention
In order to overcome the shortcoming of above-mentioned prior art, the purpose of this utility model is to provide a kind of boiler smoke degree of depth cooling residual heat retracting device with independent operating system, by the flue gas cryocooler flue-gas temperature is reduced to about 90 ℃, the flue gas heat that reclaims adds hot-air by steam air heater, improve combustion air temperature, when reclaiming fume afterheat, not only do not influence the long period safe operation of existing therrmodynamic system, reduced exhaust gas temperature, and the water consumption of having saved desulfurizing tower, improve unit efficiency, increased unit output.
For achieving the above object, the technical solution of the utility model is achieved in that a kind of boiler smoke degree of depth cooling residual heat retracting device, comprising:
A flue gas cryocooler 8, flue gas cryocooler 8 inlet flue ducts connect with electrostatic precipitator 3 exhaust pass and are connected, and flue gas cryocooler 8 exhaust pass connect with the inlet flue duct of desulfurizing tower 9 and are connected,
A steam air heater 4, the inlet of cold air of steam air heater 4 links to each other with pressure fan 5, the hot air outlet of steam air heater 4 connects with air preheater 2 and is connected, steam air heater 4 cooling water outlets are communicated with flue gas cryocooler 8 cooling water inlets by water pump 6, flue gas cryocooler 8 hot water outlets are connected with the hot water inlet of steam air heater 4, form an independently water circulation system thus.
Can install booster fan 7 additional between flue gas cryocooler 8 inlet flue ducts and electrostatic precipitator 3 exhaust pass.
Essence of the present utility model is by the gas-water heat-exchanger rig as flue gas cryocooler 8, utilize electrostatic precipitator 3 outlet fume afterheats to heat cold water in the independent water circulation system, again the hot water of flue gas cryocooler 8 hot water outlets is delivered to steam air heater 4 heats cold air, improve the air themperature that enters air preheater 2, thereby realize improving boiler efficiency, increase the purpose of unit net efficiency.
The utility model is compared with the machine set system that low-pressure coal saver or gas-gas heat exchanger (GGH) flue gas retracting device are installed, and has following characteristics:
1) the utlity model has independently operational system, water circulation system independently, do not change miscellaneous equipment, system etc. so the active service unit only need increase this cover system and just can finish transformation, reach the boiler exhaust gas heat recovery, reduce exhaust gas temperature, improve boiler efficiency, increase the purpose of unit output, realize efficient, energy-conservation, reduction of discharging target.Even break down in the utility model use, only stop to repair faulty equipment and get final product, do not influence the normal operation of unit.
2) gentle-all advantages of gas heat exchanger (GGH) flue gas retracting device that flue gas cryocooler 8 has low-pressure coal saver.Flue gas cryocooler 8 is installed between electrostatic precipitator 3 and the desulfurizing tower 9, guarantees flue gas cryocooler 8 in the work of low dirt district, and flue gas corrosion wearing and tearing, adhesion are stopped up lighter, reliable operation, efficient height; Booster fan 7 is installed at before the flue gas cryocooler 8, and this adding that has guaranteed flue gas cryocooler 8 does not change the unit original system, installation period weak point, small investment, instant effect; After installing flue gas cryocooler 8 additional, exhaust gas temperature reduces, and fume afterheat is recycled, and boiler efficiency improves, and unit output increases; The wet desulphurization water consumption greatly mainly is that absorption tower adiabatic evaporation process water consumption is too big, and after the flue gas process flue gas cryocooler 8, temperature feeds desulfurizing tower 9 near dropping to best desulfurization temperature again, desulfuration efficiency height not only, and evaporated water greatly reduces, and saturation water and moisture discharge amount, the sewage discharge and disposal expense of chimney 11 outlets simultaneously reduce greatly.
3) traditional steam air heater heat transferring medium is steam and air, and steam air heater 4 relates to hot water, the heat exchange of air two media in the utility model.Because the heat that flue gas cryocooler 8 reclaims is not too big, then steam air heater 4 thermic loads are little, can take common heat exchangers design principle and method, and are simple and reliable for structure.Install steam air heater 4 preheated airs additional, improved the inlet temperature of air preheater 2, prevent cold end corrosion.Because steam air heater 4 heat exchange amounts are not too big, the cold air temperature raises little (general<50 ℃), and the utility model is independent of the unit original system, has independent adjustable water circulation system, guaranteed to install additional steam air heater 4 back air preheater 2 heating surface wall temperatures and be higher than flue gas acid dew point temperature and less air preheater 2 heat exchange influential effects, do not cause the sulfuric acid corrosion phenomenon so air preheater 2 heating surfaces surface smoke condensation can not occur, do not influence the normal use of air preheater 2.
4) flue gas directly feeds desulfurizing tower 9 through flue gas cryocooler 8 backs, after 11 dischargings of wet chimney.Because most of thermal power plant all has desulfurizing tower 9, and existing desulfur technology comparative maturity, possesses smoke treatment dewing corrosion problem, and follow-up flue and wet chimney have carried out preservative treatment, the sour pond of Sheng is arranged at wet chimney 11 bottoms, and flue gas dewfall in wet chimney 11 forms sulfuric acid and falls into the sour pond of Sheng, sends into desulfurizing tower 9 through acid-proof pump 10 and handles, so flue gas cryocooler 8 outlet flue gases can directly feed desulfurizing tower 9 and carry out subsequent treatment, do not have security hidden trouble.
Description of drawings
Accompanying drawing is a system architecture schematic diagram of the present utility model.
The specific embodiment
Below in conjunction with accompanying drawing structural principle of the present utility model and operation principle are elaborated.
Referring to accompanying drawing, a kind of boiler smoke degree of depth cooling residual heat retracting device, comprise: a flue gas cryocooler 8 and a steam air heater 4, flue gas cryocooler 8 comprises 1 cooling water inlet, 1 hot water outlet, 1 gas approach, 1 exhanst gas outlet, realizes the exchange heat between flue gas and the cold water.Flue gas cryocooler 8 inlet flue ducts connect with electrostatic precipitator 3 exhaust pass and are connected, and flue gas cryocooler 8 exhaust pass connect with the inlet flue duct of desulfurizing tower 9 and are connected.Steam air heater 4 comprises 1 hot water inlet, 1 cooling water outlet, 1 inlet of cold air, 1 hot air outlet, realize the exchange heat between hot water and the cold air, the inlet of cold air of steam air heater 4 links to each other with pressure fan 5, the hot air outlet of steam air heater 4 connects with air preheater 2 and is connected, steam air heater 4 cooling water outlets are communicated with flue gas cryocooler 8 cooling water inlets by water pump 6, flue gas cryocooler 8 hot water outlets are connected with the hot water inlet of steam air heater 4, form an independently water circulation system thus.
Booster fan 7 places between electrostatic precipitator 3 and the flue gas cryocooler 8, and desulfurizing tower 9 follows flue gas cryocooler 8 closely and arranges, is wet chimney 11 at last; Steam air heater 4 is arranged in before the air preheater 2.
Cooling water enters flue gas cryocooler 8 from cooling water inlet, carries out exchange heat with flue gas and becomes hot water, and hot water enters steam air heater 4 from the hot water inlet that flue gas cryocooler 8 hot water outlets flow out through steam air heater 4, carries out becoming cold water after the exchange heat with cold air; Cold water is sent into flue gas cryocooler 8 by steam air heater 4 cooling water outlets again through water pump 6, thereby forms an independently water circulation system.
Cold air is delivered to steam air heater 4 by pressure fan 5 through the inlet of cold air of steam air heater 4 and is carried out preheating; Hot-air enters air preheater 2 further preheatings through the hot air outlet of steam air heater 4; It is combustion-supporting that air preheater 2 outlet hot-airs are sent into the burner hearth of boiler 1, improves combustion position; Boiler 1 furnace outlet flue gas enters air preheater 2 preheated airs through flue; Air preheater 2 outlet flue gases directly feed electrostatic precipitator 3 and carry out flue gas ash removal; Electrostatic precipitator 3 outlet flue gases are sent into flue gas cryocooler 8 through booster fan 7, reduce flue-gas temperature, reclaim fume afterheat; Flue gas cryocooler 8 outlet flue gases directly feed desulfurizing tower 9 and carry out the desulfurization processing; Desulfurizing tower 9 outlet flue gases are discharged through wet chimney 11.Wet chimney 11 is by explosive expansion joint method Ti alloy lining in addition, and chimney bottom has the sour pond of Sheng acid-proof pump 10 will contain in the sour pond acid to squeeze into desulfurizing tower 9 and handle, be beneficial to SO in the smoke treatment
3The sulfuric acid corrosion problem of bringing etc. dewfall.
In the accompanying drawing, the 1st, boiler; The 2nd, air preheater; The 3rd, electrostatic precipitator; The 4th, steam air heater; The 5th, pressure fan; The 6th, water pump; The 7th, booster fan; The 8th, the flue gas cryocooler; The 9th, desulfurizing tower; The 10th, acid-proof pump; The 11st, wet chimney.