The method that improves the recyclable smoke discharging residual heat quality of power plant boiler and utilize step by step
Technical field
The present invention relates to a kind of method that improves the recyclable smoke discharging residual heat quality of power plant boiler and utilize step by step.
Background technology
Thermal power plant's coal-burning boiler provides the generated energy of generating set, and great amount of heat energy is discharged at chimney with boiler smoke simultaneously; Advocating energetically under the background of energy-saving and emission-reduction now, for this coal-burning boiler of thermal power plant, how to reduce the smoke evacuation heat-energy losses, thereby energy savings, the protection environment very important meaning is arranged.
The operating flue gas loss of power plant boiler is a most important heat loss, if can the smoke exhaust heat of boiler maximized reclaim and the generating set that is used in, then can improve boiler efficiency, economic benefit and social benefit.The method of in the past recycling for the power plant boiler smoke discharging residual heat has:
One of which, as shown in Figure 1, heat exchanger 2 is arranged in the exit flue 3 of boiler 1, the smoke discharging residual heat of the boiler 1 that reclaims is used for the boiler feedwater of heating boiler heat regenerative system 4 separately, thereby the steam that reduces steam turbine 5 draws gas, to improve the generating efficiency of steam turbine 5; In the method, the temperature at general heat exchanger 2 two ends is respectively 115 ℃ and 90 ℃, and the temperature difference is 25 ℃; The quality of fume afterheat is not high; Therefore heat exchanger 2 can only be used for the also lower low-pressure heater 41 of heating boiler heat regenerative system 4 temperature, and the heat of recovery is few, DeGrain.Lower thus exhaust gas temperature makes heat exchanger efficiency reduce, and does not have the effect of heating boiler feedwater.
Its two, as shown in Figure 2, heat exchanger 2 is arranged in the exit flue 3 of boiler 1; Flue gas heater 8 is located between the desulfurizing tower 6 and chimney 7 of boiler exhaust gas flue 3, the smoke discharging residual heat of the boiler 1 that reclaims is used for the flue gas heater 8 behind exit flue 3 desulfurizing towers 6 of boiler 1 separately, to improve the flue-gas temperature after desulfurization; And improved exhaust gas temperature through chimney 7; So reduce flue gas to chimney 7 corrosion in, the smoke evacuation height of the chimney 7 that raise has reduced environmental pollution.In the method, the temperature at general heat exchanger 2 two ends is respectively 115 ℃ and 90 ℃, and the temperature difference is 25 ℃, and the quality of same fume afterheat is not high, and heat exchanger 2 also can only be used to add the lower flue gas of temperature behind the thermally desulfurizing, the raising boiler efficiency is not exerted an influence.
Summary of the invention
Technical problem to be solved by this invention provides a kind of method that improves the recyclable smoke discharging residual heat quality of power plant boiler and utilize step by step; Utilize this method can effectively improve the recyclable smoke discharging residual heat quality of boiler; Make that the recycling efficient of boiler exhaust gas waste heat is higher; Improve boiler and Efficiency of Steam Turbine, reduced the generating energy consumption.
For solving the problems of the technologies described above; The method that the present invention improves recyclable smoke discharging residual heat quality of power plant boiler and utilization step by step is used to heat the air that gets into air preheater at the air preheater front end serial connection thermal source of boiler air input cold air duct; Serial connection first heat exchanger in the boiler exhaust gas flue, first heat exchanger be located at after the air preheater of boiler exhaust gas flue, before the desulfurizing tower and be used for the boiler feedwater of heating boiler heat regenerative system.
Above-mentioned thermal source can be an air heater; Second heat exchanger is located at before the desulfurizing tower of boiler exhaust gas flue, after first heat exchanger; The second heat exchanger heat provides air heater to be used to improve the air themperature that gets into said air preheater; Transmit heat through fluid media (medium) between the air heater and second heat exchanger, fluid media (medium) is a water, or anti-icing fluid.
The heat of above-mentioned thermal source also can be used to improve the air themperature that gets into said air preheater from extracted steam from turbine.
For making full use of fume afterheat; Be connected in series flue gas heater between the desulfurizing tower of this method in the boiler exhaust gas flue and the chimney; The heat of flue gas heater is provided by first heat exchanger, and perhaps the heat of flue gas heater is provided by second heat exchanger, transmits heat through fluid media (medium) between the flue gas heater and first heat exchanger or second heat exchanger; Fluid media (medium) is a water, or anti-icing fluid.
For further utilizing fume afterheat; This method also is connected in series the 3rd heat exchanger in the boiler exhaust gas flue; The 3rd heat exchanger is located at before the desulfurizing tower of boiler exhaust gas flue, after first heat exchanger, the 3rd heat exchanger heat provides flue gas heater to be used to improve the flue-gas temperature behind desulfurizing tower, transmits heat through fluid media (medium) between flue gas heater and the 3rd heat exchanger; Fluid media (medium) is a water, or anti-icing fluid.
Be provided with and be connected for convenient, first heat exchanger can be located at after the air preheater of boiler exhaust gas flue, before the deduster, perhaps first heat exchanger be located at after the deduster of boiler exhaust gas flue, before the air-introduced machine.
The second above-mentioned heat exchanger is located at before the desulfurizing tower in the boiler exhaust gas flue, after the booster fan.
Be heat exchange effect that improves boiler feedwater and the heat exchange area that reduces by first heat exchanger, the heat transferring medium pipeline of the first above-mentioned heat exchanger is serially connected with in the boiler heat regenerative system through flow control valve, is used to heat whole boiler feedwaters.When first heat exchanger was all flowed through in boiler feedwater, the corresponding increase of flow made the first less heat exchanger of heat exchange area have same heat exchange effect.
For making things convenient for the utilization of fume afterheat, the heat between the above-mentioned air heater and second heat exchanger transmits medium can carry out the adjusting of flow size through variable frequency pump or flow control valve.
For making things convenient for the utilization of fume afterheat, the heat between the above-mentioned flue gas heater and first heat exchanger, between flue gas heater and second heat exchanger transmits medium and can carry out the adjusting of flow size through variable frequency pump or flow control valve.
For making things convenient for the utilization of fume afterheat, the heat between above-mentioned flue gas heater and the 3rd heat exchanger transmits medium can carry out the adjusting of flow size through variable frequency pump or flow control valve.
Because improving the method for recyclable smoke discharging residual heat quality of power plant boiler and utilization step by step, the present invention adopted technique scheme; Promptly the air preheater front end serial connection thermal source at boiler air input cold air duct is used to heat the air that gets into air preheater; Serial connection first heat exchanger in the boiler exhaust gas flue, first heat exchanger be located at after the air preheater of boiler exhaust gas flue, before the desulfurizing tower and be used for the boiler feedwater of heating boiler heat regenerative system.Utilize this method can effectively improve the recyclable smoke discharging residual heat quality of boiler, make that the recycling efficient of boiler exhaust gas waste heat is higher, improved boiler and Efficiency of Steam Turbine, reduced the generating energy consumption.
Description of drawings
Below in conjunction with accompanying drawing and embodiment the present invention is done further detailed description:
Fig. 1 is the connection sketch map of employing heat exchanger heating boiler heat regenerative system low-pressure heater,
Fig. 2 discharges fume through the connection sketch map of flue gas after desulfurization temperature for adopting the heat exchanger heating boiler,
Fig. 3 is a principle schematic of the present invention,
Fig. 4 has increased the principle schematic of other heat exchangers for the present invention.
The specific embodiment
As shown in Figure 3; The method that the present invention improves recyclable smoke discharging residual heat quality of power plant boiler and utilization step by step is used to heat the air that gets into air preheater 10 at the air preheater 10 front ends serial connection thermal source 9 of boiler 1 air input cold air duct; In boiler 1 exit flue 3 serial connection first heat exchanger 21, the first heat exchangers 21 be located at after the air preheater 10 of boiler exhaust gas flue 3, before the desulfurizing tower 6 and be used for the boiler feedwater of heating boiler heat regenerative system 4.
Above-mentioned thermal source 9 can be an air heater; Second heat exchanger 23 is located at before the desulfurizing tower 6 of boiler exhaust gas flue 3, after first heat exchanger 21; Second heat exchanger, 23 heats provide air heater to be used to improve the air themperature that gets into said air preheater 10; Transmit heat through fluid media (medium) between the air heater and second heat exchanger 23, fluid media (medium) is a water, or anti-icing fluid.
The heat of above-mentioned thermal source 9 also can draw gas from steam turbine 5, is used to improve the air themperature that gets into said air preheater 10.
As shown in Figure 4; For making full use of fume afterheat, be connected in series flue gas heater 8 between the desulfurizing tower 6 of this method in boiler exhaust gas flue 3 and the chimney 7, the heat of flue gas heater 8 is provided by first heat exchanger 21; Perhaps the heat of flue gas heater 8 is provided by second heat exchanger 23; Transmit heat through fluid media (medium) between the flue gas heater 8 and first heat exchanger 21 or second heat exchanger 23, fluid media (medium) is a water, or anti-icing fluid.
As shown in Figure 4; For further utilizing fume afterheat, this method in boiler exhaust gas flue 3, also be connected in series the 3rd heat exchanger 22, the three heat exchangers 22 be located at before the desulfurizing tower 6 of boiler exhaust gas flue 3, after first heat exchanger 21; The 3rd heat exchanger 22 heats provide flue gas heater 8 to be used to improve the flue-gas temperature behind desulfurizing tower 6; Transmit heat through fluid media (medium) between flue gas heater 8 and the 3rd heat exchanger 22, fluid media (medium) is a water, or anti-icing fluid.
Be provided with and be connected for convenient, first heat exchanger 21 can be located at after the air preheater 10 of boiler exhaust gas flue 3, before the deduster 11, perhaps first heat exchanger 21 be located at after the deduster 11 of boiler exhaust gas flue 3, before the air-introduced machine 12.
The second above-mentioned heat exchanger 23 is located at before the desulfurizing tower 6 in the boiler exhaust gas flue 3, after the booster fan 13.
As shown in Figure 3, be heat exchange effect that improves boiler feedwater and the heat exchange area that reduces by first heat exchanger 21, the heat transferring medium pipeline of the first above-mentioned heat exchanger 21 is serially connected with in the boiler heat regenerative system 4 through flow control valve 43, is used to heat whole boiler feedwaters.When first heat exchanger 21 was all flowed through in boiler feedwater, the corresponding increase of flow made the first less heat exchanger of heat exchange area have same heat exchange effect.
For making things convenient for the utilization of fume afterheat, the heat between the above-mentioned air heater and second heat exchanger 23 transmits the size that medium is regulated flow by variable frequency pump 24 or flow control valve.
For making things convenient for the utilization of fume afterheat, the heat between the above-mentioned flue gas heater and first heat exchanger 21, between flue gas heater and second heat exchanger 23 transmits medium is regulated flow by variable frequency pump or flow control valve size.
As shown in Figure 4, for making things convenient for the utilization of fume afterheat, the heat between above-mentioned flue gas heater 8 and the 3rd heat exchanger 22 transmits the size that medium is regulated flow by variable frequency pump 25 or flow control valve.
This method is through practical application; Owing to be connected in series thermal source at the air preheater front end, make the air themperature that gets into air preheater be increased to 68 ℃ by room temperature, the air themperature that after the air preheater heating, gets into boiler is 340 ℃; Boiler exhaust gas is after air preheater carries out heat exchange; The flue-gas temperature of discharging air preheater can rise to 162 ℃ by original 131 ℃, and 31 ℃ difference variation is arranged, and the quality of residual heat from boiler fume has greatly improved; Value also just improves greatly, makes the step by step utilization of boiler smoke in exit flue become possibility; Because flue-gas temperature reduces in exit flue step by step; First heat exchanger that therefore will be used for the heating boiler feedwater is located at prime; And the 3rd heat exchanger that is used to heat flue gas after desulfurization is located at the back level, and the temperature at prime heat exchanger two ends is respectively 155 ℃ and 130 ℃, so can be used for the boiler feedwater of heating boiler heat regenerative system; The steam that has further reduced steam turbine draws gas, and effectively improves the generating efficiency of steam turbine; The temperature at level heat exchanger two ends, back is respectively 110 ℃ and 80 ℃, and the flue-gas temperature of this moment is lower, but still can be through the flue gas of flue gas heater heating behind desulfurizing tower; The flue-gas temperature that make to get into chimney is raised to 80 ℃ from original 50 ℃; Improve exhaust gas temperature, the raising of exhaust gas temperature has promoted the smoke evacuation height of chimney; Reducing flue gas, reduced the pollution of smoke evacuation to environment in the chimney corrosion.
For more making full use of fume afterheat; Thermal source in this method also can obtain from fume afterheat; Can be connected in series one second heat exchanger again with back level heat exchanger at above-mentioned prime heat exchanger; The temperature at these heat exchanger two ends is respectively 130 ℃ and 110 ℃, and at the air preheater front end serial connection air heater of boiler air input cold air duct, the heat of this second heat exchanger provides air heater to be used to heat the air of room temperature; Make the air themperature that gets into air preheater reach 68 ℃, to improve air preheater smoke discharging residual heat quality.
According to the heating principle, introduce extracted steam from turbine or be connected in series an electric heater or steam heater etc. at the air preheater front end of boiler air input cold air duct, can play the effect that adds hot-air equally.
This method is through the air of heating boiler air input cold air duct; Improved the quality of residual heat from boiler fume; Through heat exchanger residual heat from boiler fume is recycled step by step; Effectively improve the operational efficiency of boiler and steam turbine, reduced energy consumptions such as fire coal, had good social benefit and economic benefit.