The integrated cold junction complex optimum of power station machine stove system
Technical field
The invention belongs to energy-saving and emission-reduction field, be particularly related to the integrated cold junction complex optimum of a kind of power station machine stove system, specifically: (1) air side, adopt turbine discharge and low-pressure pumping steam step by step cold air to be carried out to preheating, the air after preheating enters primary air preheater again and is further heated to temperature required; (2) flue gas of boiler economizer outlet enters first, second grade of cigarette water-to-water heat exchanger of primary air preheater and bypass flue simultaneously, and outlet flue gas enters third level cigarette water-to-water heat exchanger after boiler tail converges, and enters thereafter dedusting and desulfurizer again; (3) first order cigarette water-to-water heat exchanger can be used for adding Hot gas turbine feedwater, Substitute For Partial high pressure extraction, and second and third grade of cigarette water-to-water heat exchanger also can be used for heating drawing gas of the condensate water of higher temperature, alternative elevated pressures; (4) can be according to unit flue-gas temperature level, the parameter etc. of drawing gas at different levels, the fume afterheat that flexible design is different utilizes the connected mode of mode and cigarette water-to-water heat exchanger at different levels and Turbine Steam water system.
Background technology
The energy-saving and emission-reduction of large electric power plant unit are Chinese important energy source strategies.In China, coal-burning power plant has consumed the coal production of national nearly half, and the exhaust gas temperature of general coal-fired unit, 120-140 DEG C of left and right, causes a large amount of low-grade energies directly discharged to environment, brings huge residual heat resources waste.Along with rising steadily of Coal Energy Source price in recent years, day by day improve taking coal as basic cost of electricity-generating, each thermal power plant is faced with huge economizer pressure, constantly seeks to reduce coal consumption, saves the new application technology in energy aspect, and strengthen relevant fund input.
Effective utilization of fume afterheat is the energy-conservation main path of coal-fired power station boiler, utilize boiler tail flue gas waste-heat condensate water, can not only effectively reduce the exhaust gas temperature of boiler, improve boiler efficiency, and can squeeze the regenerative steam of part steam turbine by the heat that afterheat heat exchanger is inputted hot system, in the situation that steam turbine admission quantity of steam is constant, squeezing draws gas returns to steam turbine and continues the acting of expanding, the rank of drawing gas of squeezing is higher, and the work of drawing gas is just more.And adopt low-level bled steam preheating cold air, and displace high-temperature flue gas heat-setting water, can squeeze high level drawing gas and continue acting.Therefore, in the situation that fuel input quantity is constant, can make steam turbine power output increase, improve the thermal efficiency and the economy of unit.
Niederaussem power plant of Germany is for recycling high-temperature flue gas waste heat, improve condensate water inlet temperature, substituting the more steam turbine of high level draws gas, integrated bypass flue technology in smoke waste heat utilization system, the high-temperature flue gas part flowing out from economizer exit enters air preheater, another part enters bypass flue, high-pressure feed water in heating high-temperature heat-exchanging and the condensate water in cryogenic heat exchanger, after parallel gas passes, arrange cold wind preheater, the flat lower waste heat of cigarette warm water in recovered flue gas.
The residual neat recovering system of Niederaussem power plant of Germany can be saved the about 7g/kWh of generating standard coal consumption, but because German power plant generally adopts brown coal as fuel, exhaust gas temperature is generally higher, and even up to 160 DEG C, therefore the tail flue gas waste heat amount of German coal-burning power plant is very high.And Coal-fired Power Plants In China adopts common anthracite and bituminous coal as fuel, flue-gas temperature level is relatively low, and generally 120-140 DEG C of left and right, and the actual conditions of German power plant have larger difference, due in low-temperature flue gas in boiler tail usually containing just like SO
2, SO
3, NO
xdeng corrosive gas, below wall surface temperature drops to acid dew point time, easily there is strong low-temperature flue gas corrosion in low temperature tube wall, while forms taking calcium sulfate as main cement-like material with the flying dust in flue gas, fume side flowing resistance is increased, blower fan power consumption increases, and has aggravated the corrosion of tube wall, has a strong impact on the safe and economical operation of boiler.Therefore the residual neat recovering system of German Niederaussem power plant be not suitable for Chinese coal fired power plant.
The present invention proposes the integrated cold junction complex optimum of a kind of power station machine stove system, solved the deficiency of above-mentioned technology, energy counterpart, cascade utilization tail flue gas energy, and utilize turbine low pressure cylinder to draw gas and the system and method for boiler tail flue gas preheated air.This new energy utilizes thinking, do not changing under the prerequisite of air preheater exit gas temperature exactly, utilize bypass flue and low level to draw gas to reclaim the condensate water of the flue gas heat heating higher level of higher quality, substitute drawing gas of higher level, the caloric receptivity that air preheater reduces is made up by draw gas condensation heat and boiler tail flue gas waste heat of turbine low pressure cylinder, can comprehensively prevent the too low cold end corrosion causing of flue-gas temperature, be a kind of new technology that is really applicable to the energy-saving and emission-reduction of Coal Combustion in China power station.
Summary of the invention
The object of the invention is to have proposed the integrated cold junction complex optimum of a kind of power station machine stove system, this system mainly comprises steam turbine high-pressure cylinder, Steam Turbine Through IP Admission and the turbine low pressure cylinder of series connection, boiler main economizer, flue collector, bypass flue, converge flue, primary air preheater, cigarette water-to-water heat exchanger, high-pressure heater, oxygen-eliminating device, low-pressure heater, gas-air heater and the condensing air preheater that draws gas, it is characterized in that: after flue collector 2 and bypass flue 3 parallel connections, upper end is connected with main economizer 1, lower end with converge flue 22 and be connected, in bypass flue 3, set gradually first order cigarette water-to-water heat exchanger 5 and second level cigarette water-to-water heat exchanger 6, third level cigarette water-to-water heat exchanger 16 is arranged on and converges in flue 22, primary air preheater 4 connects respectively and converges flue 22, flue collector 2 and the fourth stage condensing air preheater 27 that draws gas, and wherein fourth stage condensing air preheater 27, third level steam-extracting type air preheater 26, second level condensing air preheater 25 and the first order condensing air preheater 24 that draws gas that draws gas that draws gas is connected, converging flue 22 exports after deduster 23 and is connected to desulfurizer, the import of first order cigarette water-to-water heat exchanger 5 is connected to high-pressure heater 9 both sides No. three by the 28th valve, the 29th valve, the outlet of first order cigarette water-to-water heat exchanger 5 is connected to high-pressure heater 7 both sides No. one by the 30th valve, the 31st valve, and No. two high-pressure heater 8 both sides are connected with the 29th valve and the 31st valve respectively, No. one to No. three high-pressure heater is connected with steam turbine high-pressure cylinder 17, Steam Turbine Through IP Admission 18 respectively, second level cigarette water-to-water heat exchanger 6 exports by the 33rd valve and is connected in low-pressure heater 11 1 sides No. five, second level cigarette water-to-water heat exchanger 6 imports are connected in low-pressure heater 11 opposite sides No. five by the 33rd valve, the import of third level cigarette water-to-water heat exchanger 16, outlet is by the 34th valve, the 35th valve is connected in low-pressure heater 12 both sides No. six, wherein between second level cigarette water-to-water heat exchanger 6 and third level cigarette water-to-water heat exchanger 16, directly connect by the 36th valve, No. five low-pressure heaters 11, No. six low-pressure heaters 12, No. seven low-pressure heaters 13 and No. eight low-pressure heaters 14 form cascaded structure by condensate water and supply line, and be connected with turbine low pressure cylinder 19 exhaust outlets respectively, turbine low pressure cylinder 19 exhaust outlets are also connected with No. eight low-pressure heater 14 imports by condenser 20.
Converging flue 22 and the fourth stage cross-over connection gas-air heater 15 in the flue that condensing air preheater 27 is connected with primary air preheater 4 that draws gas, replace third level cigarette water-to-water heat exchanger 16.
Be arranged in flue collector 2, bypass flue 3 and converge the first order, the second level and third level cigarette water-to-water heat exchanger Mist heat recovering in flue 22 and that be connected with No. one to No. three high-pressure heater with No. five to No. eight low-pressure heaters, to add Hot gas turbine condensate water or feedwater.
In air preheat side: the first order to the fourth stage condensing air preheater preheating cold air step by step that draws gas, at different levels drawing gas flows into respectively this grade in the condensate water after heat release in condensing air preheater of drawing gas and draw gas in the return pipe of corresponding low-pressure heater.
Utilize side at fume afterheat: economizer 1 exports flue gas major part and still enters primary air preheater 4 by flue collector 2, another part enters bypass flue 3, successively by after first order cigarette water-to-water heat exchanger 5 and second level cigarette water-to-water heat exchanger 6, two strands of flue gases enter and converge flue 22, by third level cigarette water-to-water heat exchanger 16 and deduster 23, enter subsequently desulfurization unit, finally discharge.
In condensate water heated side: extract condensate water from certain grade of inlet of high pressure heater and be back to more senior high-pressure heater outlet after 5 heating of first order cigarette water-to-water heat exchanger, extract condensate water from certain grade of low-pressure heater entrance and be back to more senior low-pressure heater outlet after 6 heating of second level cigarette water-to-water heat exchanger.
The invention has the beneficial effects as follows that the integrated cold junction complex optimum of provided power station machine stove system has following features:
1. adopt the condensing air preheater plural serial stage that draws gas to arrange, preheating cold air step by step, heat exchange loss is little; What the condensing air preheater that draws gas extracted is the low-pressure steam of steam turbine, and temperature, pressure are very low, and its acting ability in steam turbine is low, is conducive to energy-conservation.Steam is the heat exchange mode of steam-condensation phase-change heat-exchange at the heat exchange mode in solidifying regenerative air heater that draws gas, and discharges a large amount of latent heat, and heating target is non-corrosive air, and heat exchanger does not exist etching problem, and air can be preheating to more than 100 degrees Celsius.
2. the layout of the main heat exchanger of fume side forms series parallel structure, is conducive at utmost utilize fume afterheat.
3. three grades of cigarette water-to-water heat exchangers utilize mode more flexible, can pass through valve flexible modulation, cigarette water-to-water heat exchanger and heater adopt and are arranged in parallel, the water collateral resistance that condensate water reduces because of the heater of not flowing through is enough to compensate the resistance that its cigarette water-to-water heat exchanger of flowing through increases, therefore it does not need to set up water pump, be more conducive to transform on the basis of the hot system of former power plant.
4. this system is open flexibly, as required, can remove the condensing air preheater that draws gas, with flue gas-air heat exchanger directly to air release heat.
5. the condensing air preheater that draws gas is set, utilizes turbine discharge used heat to carry out preheating cold air, can make cold air be heated to 8-20 DEG C, can effectively avoid frozen problem in winter, utilize used heat can save a large amount of low temperature heat energies simultaneously, save recirculated water; Meanwhile, the condensing air preheater that draws gas is also applicable to Air-cooled Unit, and general exhaust steam pressure of air-cooled unit is higher, and steam discharge parameter is higher, introduces the condensing air preheater that draws gas, and air themperature can be brought up to 15-40 DEG C.
6. this system also can not arrange third level cigarette water-to-water heat exchanger, can reduce flue gas resistance, further reduces investment for trnasforming urban land, and keeps higher exhaust gas temperature, substantially solves the cold end corrosion problem causing because boiler tail flue gas temperature is too low in UTILIZATION OF VESIDUAL HEAT IN process.Can reduce generating standard coal consumption 6-11g/KWh, remarkable in economical benefits according to calculating this integral system.
Brief description of the drawings
Fig. 1 is the integrated cold junction complex optimum of power station machine stove system schematic
Fig. 2 is the integrated cold junction complex optimum of the power station machine stove system schematic with flue gas-air preheater
Embodiment
The present invention proposes the integrated cold junction complex optimum of a kind of power station machine stove system.Be explained below in conjunction with accompanying drawing and example.
In the integrated cold junction complex optimum of power station machine stove system schematic as shown in Figure 1, the integrated cold junction complex optimum of power station machine stove system mainly comprises steam turbine high-pressure cylinder, Steam Turbine Through IP Admission and the turbine low pressure cylinder of series connection, boiler main economizer, flue collector, bypass flue, converge flue, primary air preheater, cigarette water-to-water heat exchanger, high-pressure heater, oxygen-eliminating device, low-pressure heater, gas-air heater and the condensing air preheater that draws gas, wherein after flue collector 2 and bypass flue 3 parallel connections, upper end is connected with main economizer 1, lower end with converge flue 22 and be connected, in bypass flue 3, set gradually first order cigarette water-to-water heat exchanger 5 and second level cigarette water-to-water heat exchanger 6, third level cigarette water-to-water heat exchanger 16 is arranged on and converges in flue 22, primary air preheater 4 connects respectively and converges flue 22, flue collector 2 and the fourth stage condensing air preheater 27 that draws gas, and wherein fourth stage condensing air preheater 27, third level condensing air preheater 26, second level condensing air preheater 25 and the first order condensing air preheater 24 that draws gas that draws gas that draws gas that draws gas is connected, converging flue 22 exports after deduster 23 and is connected to desulfurizer, the import of first order cigarette water-to-water heat exchanger 5 is connected to high-pressure heater 9 both sides No. three by the 28th valve, the 29th valve, the outlet of first order cigarette water-to-water heat exchanger 5 is connected to high-pressure heater 7 both sides No. one by the 30th valve, the 31st valve, and No. two high-pressure heater 8 both sides are connected with the 29th valve and the 31st valve respectively, No. one to No. three high-pressure heater is connected with steam turbine high-pressure cylinder 17, Steam Turbine Through IP Admission 18 respectively, second level cigarette water-to-water heat exchanger 6 exports by the 33rd valve and is connected in low-pressure heater 11 1 sides No. five, second level cigarette water-to-water heat exchanger 6 imports are connected in low-pressure heater 11 opposite sides No. five by the 33rd valve, the import of third level cigarette water-to-water heat exchanger 16, outlet is by the 34th valve, the 35th valve is connected in low-pressure heater 12 both sides No. six, wherein between second level cigarette water-to-water heat exchanger 6 and third level cigarette water-to-water heat exchanger 16, directly connect by the 36th valve, No. five low-pressure heaters 11, No. six low-pressure heaters 12, No. seven low-pressure heaters 13 and No. eight low-pressure heaters 14 form cascaded structure by condensate water and supply line, and respectively with the 3rd steam turbine 19 exhaust outlets be connected, the 3rd steam turbine 19 exhaust outlets are also connected with No. eight low-pressure heater 14 imports by condenser 20.
As shown in Figure 2, can gas-air heater 15 be set in 26 outlets of steam-extracting type air preheater, with flue gas-air heat exchanger 15, directly to air release heat, Mist heat recovering is for further preheated air; As shown in Figure 1, gas-air heater 15 also can be set, and third level cigarette water-to-water heat exchanger 16 be set for heat-setting water or feedwater, now, can extract more senior drawing gas for further preheated air.This system is open flexibly, as required, can remove the fourth stage condensing air preheater 27 that draws gas, as shown in Figure 2, and the described integrated cold junction complex optimum of a kind of power station machine stove system; Third level cigarette water-to-water heat exchanger 16 can be set completely, so just can reduce flue gas resistance, reduce investment for trnasforming urban land.Now, boiler tail flue gas temperature is at 120-150 DEG C, to back-end surfaces without any low-temperature flue gas corrosion, therefore do not need to adopt special anticorrosive, can further reduce investment for trnasforming urban land.
Its principle is as follows: air side, extracting successively part turbine discharge and low level draws gas, by first order condensing air preheater 24, second level condensing air preheater 25, third level condensing air preheater 26 and the fourth stage condensing air preheater 27 preheating cold air step by step that draws gas that draws gas that draws gas that draws gas, draw gas and flow into respectively in the return pipe of the next stage low-pressure heater under the correspondence of drawing gas in the condensate water after heat release in condensing air preheater of drawing gas respectively.
Fume side, economizer 1 exports the flue gas of 350-450 DEG C and is divided into two-way: a road access primary air preheater 4, first order cigarette water-to-water heat exchanger 5 and second level cigarette water-to-water heat exchanger 6 are passed through successively through bypass flue 3 in another road, depending on unit parameter, extract condensate water from certain grade of inlet of high pressure heater and after 5 heating of first order cigarette water-to-water heat exchanger, be back to more senior high-pressure heater outlet, extract condensate water from certain grade of low-pressure heater entrance and after 6 heating of second level cigarette water-to-water heat exchanger, be back to more senior low-pressure heater outlet, outlet flue gas converges flue 22 at afterbody and mixes.
The present invention is based on energy counterpart, cascade utilization principle is rationally utilized boiler tail flue gas waste heat, and propose first to utilize turbine low pressure cylinder to draw gas and boiler tail flue gas this method of preheated air step by step, reduce accordingly the caloric receptivity of air preheater, can reclaim the fume afterheat of higher quality for heating the condensate water of more senior heater, squeeze higher drawing gas, effectively alleviate in UTILIZATION OF VESIDUAL HEAT IN process cold end corrosion problem heating surface being caused after lower than acid dew point because of boiler tail flue gas temperature simultaneously, can reduce generating standard coal consumption 6-11g/KWh according to calculating this system, remarkable in economical benefits.