Heat-adjustable flue gas waste heat recovery system for coal-fired power generation unit

Abstract

The utility model discloses a heat-adjustable flue gas waste heat recovery system for a coal-fired power generation unit. The heat-adjustable flue gas waste heat recovery system comprises a first liquid outlet branch pipe arranged on a pipeline of an inlet of a steam turbine shaft seal heater; a second liquid outlet branch pipe is arranged on the pipeline between the steam turbine No.7 low-pressure heater and the steam turbine No.6 low-pressure heater; the first liquid outlet branch pipe and the second liquid outlet branch pipe are both connected to a liquid outlet header pipe, and a condensed water booster pump is arranged on the liquid outlet header pipe; a flue gas outlet of a boiler hearth is sequentially connected with an SCR denitration device, high-temperature flue gas of an air preheater, a low-temperature economizer, a dust remover, an induced draft fan, a flue gas cooler, a desulfurizing tower and a chimney through pipelines. The liquid outlet header pipe is connected with a to-be-heated medium inlet pipe of the smoke cooler, a to-be-heated medium outlet pipe of the smoke cooler is connected with a to-be-heated medium inlet pipe of the low-temperature economizer, and a to-be-heated outlet pipe of the low-temperature economizer is connected with a heat source inlet of the primary air heater through a branch pipe. And a heat source outlet of the primary air heater is connected to the return pipe.

Description

Technical Field

[0001] The utility model relates to the technical field of coal-fired generator sets, and in particular to a flue gas waste heat recovery system with adjustable heat for coal-fired generator sets. Background Art

[0002] There are still many coal-fired power units in China with a coal consumption of more than 300g / kwh. The National Development and Reform Commission and the Energy Bureau require that the units that cannot be transformed for energy saving be gradually eliminated and shut down. In order to reduce the coal consumption of coal-fired units and improve economic efficiency as much as possible, it is necessary to utilize the waste heat of the units as much as possible, and use the coupling characteristics of the flue gas waste heat utilization system and the high and low pressure heater heat recovery system of the steam turbine to quickly adjust the water flow and condensate flow of the flue gas waste heat cascade utilization system to fully utilize the waste heat. Recycling this part of the heat can not only improve the utilization efficiency of electric coal and reduce the consumption of electric coal, but also reduce the production cost of the enterprise. Utility Model Content

[0003] The technical problem to be solved by the utility model is to provide a flue gas waste heat recovery system with adjustable heat for a coal-fired power generation unit.

[0004] In order to solve the above technical problems, the technical solution adopted by the utility model is: a flue gas waste heat recovery system with adjustable heat for a coal-fired power generation unit, comprising a shaft seal heater, a steam turbine No. 7 low-pressure heater, a steam turbine No. 6 low-pressure heater, a steam turbine No. 5 low-pressure heater, a deaerator, and a steam turbine No. 3 high-pressure heater, which are sequentially connected on the steam turbine through pipelines;

[0005] A first liquid outlet branch pipe is provided on the pipeline at the inlet of the shaft seal heater, and an electric shut-off valve and a first electric regulating valve are provided on the first liquid outlet branch pipe; a second liquid outlet branch pipe is provided on the pipeline between the steam turbine No. 7 low-pressure heater and the steam turbine No. 6 low-pressure heater, and an electric shut-off valve is provided on the second liquid outlet branch pipe; both the first liquid outlet branch pipe and the second liquid outlet branch pipe are connected to the liquid outlet main pipe, and a condensate booster pump is provided on the liquid outlet main pipe;

[0006] The flue gas outlet of the boiler furnace is connected to the SCR denitrification device, air preheater, low-temperature economizer, dust collector, induced draft fan, flue gas cooler, desulfurization tower and chimney in sequence through pipelines;

[0007] The liquid outlet main pipe is connected to the inlet pipe of the medium to be heated of the flue gas cooler, the outlet pipe of the medium to be heated of the flue gas cooler is connected to the inlet pipe of the medium to be heated of the low-temperature economizer, the outlet pipe to be heated of the low-temperature economizer is connected to the heat source inlet of the primary air heater through a branch pipe, the heat source outlet of the primary air heater is connected to the return pipe, and the return pipe is provided with a second electric regulating valve and an electric shut-off valve;

[0008] The primary fan air supply duct is connected to the air inlet of the primary air heater, the air outlet of the primary air heater is connected to the air preheater through the air preheater inlet primary air duct, and the air preheater is connected to the boiler furnace through the air preheater outlet primary air duct; a primary fan is arranged on the primary fan air supply duct.

[0009] As a preferred solution, the secondary air duct at the blower inlet is connected to the air inlet of the secondary air heater, the air outlet of the secondary air heater is connected to the air preheater through the air preheater inlet secondary air duct, and the air preheater is connected to the boiler furnace through the air preheater outlet secondary air duct; a blower is provided on the blower inlet secondary air duct.

[0010] As a preferred solution, the outlet pipe to be heated of the low-temperature economizer is connected to the heat source inlet of the secondary air heater through a branch pipe, and the heat source outlet of the secondary air heater is connected to the return pipe.

[0011] As a preferred solution, a first return pipe is provided on the outlet pipe to be heated of the low-temperature economizer, and a third electric regulating valve and an electric shut-off valve are provided on the first return pipe.

[0012] As a preferred solution, a second reflux pipe is provided on the outlet pipe of the medium to be heated of the flue gas cooler, and a fourth electric regulating valve and an electric shut-off valve are provided on the second flow pipe.

[0013] The beneficial effects of the utility model are:

[0014] After the system is put into operation, the waste heat of flue gas at the tail of the air preheater and the heat of the temperature rise of the induced draft fan are used as the primary and secondary air heaters to heat the primary and secondary air, so the coal consumption of the unit can be reduced and the economic efficiency of the unit can be improved;

[0015] After setting up the flue gas waste heat utilization system, the outlet air temperature of the primary air heater and the secondary air heater will increase, the heater can absorb more heat, the amount of exhaust steam turbine low-pressure heater and steam extraction will increase, and the unit economy will be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0017] In the figure: (1) primary air supply duct of the fan; (2) secondary air duct at the inlet of the air supply fan; (3) air supply fan; (4) primary air fan; (5) secondary air heater; (6) primary air heater; (7) secondary air duct at the inlet of the air preheater; (8) primary air duct at the inlet of the air preheater; (9) air preheater; (10) primary air duct at the outlet of the air preheater; (11) secondary air duct at the outlet of the air preheater; (12) boiler; (13) SCR denitration device;

[0018] (14) Flue gas at the inlet of low-temperature economizer; (15) Low-temperature economizer; (16) Dust collector; (17) Induced draft fan; (18) Flue gas cooler; (19) Desulfurization tower; (20) Chimney; (21) Shaft seal heater; (22) Steam turbine No. 7 low-pressure heater; (23) Steam turbine No. 6 low-pressure heater; (24) Steam turbine No. 5 low-pressure heater; (25) Deaerator; (26) Steam turbine No. 3 high-pressure heater; (27) Second electric shut-off valve; (28) First electric shut-off valve; (29) First electric regulating valve; (30) Condensate boosting pump; (31) Fourth electric regulating valve; (32) Fifth electric shut-off valve; (33) Third electric regulating valve; (34) Fourth electric shut-off valve; (35) Second electric regulating valve; (36) Third electric shut-off valve. DETAILED DESCRIPTION

[0019] The specific implementation scheme of the utility model is described in detail below in conjunction with the accompanying drawings.

[0020] like Figure 1 As shown, a heat-adjustable flue gas waste heat recovery system for a coal-fired power generation unit includes a shaft seal heater 21, a steam turbine No. 7 low-pressure heater 22, a steam turbine No. 6 low-pressure heater 23, a steam turbine No. 5 low-pressure heater 24, a deaerator 25, and a steam turbine No. 3 high-pressure heater 26, which are sequentially connected on the steam turbine through pipelines;

[0021] A first liquid outlet branch is provided on the pipeline at the inlet of the shaft seal heater 21, and a first electric shut-off valve 28 and a first electric regulating valve 29 are provided on the first liquid outlet branch; a second liquid outlet branch is provided on the pipeline between the steam turbine No. 7 low-pressure heater 22 and the steam turbine No. 6 low-pressure heater 23, and a second electric shut-off valve 27 is provided on the second liquid outlet branch; the first liquid outlet branch and the second liquid outlet branch are both connected to the liquid outlet main pipe, and a condensate booster pump 30 is provided on the liquid outlet main pipe;

[0022] The flue gas outlet of the furnace of the boiler 12 is connected to the SCR denitration device 13, the air preheater 9, the low-temperature economizer 15, the dust collector 16, the induced draft fan 17, the flue gas cooler 18, the desulfurization tower 19, and the chimney 20 in sequence through pipelines;

[0023] The liquid outlet main pipe is connected to the inlet pipe of the medium to be heated of the flue gas cooler 18, the outlet pipe of the medium to be heated of the flue gas cooler 18 is connected to the inlet pipe of the medium to be heated of the low-temperature economizer 15, the outlet pipe to be heated of the low-temperature economizer 15 is connected to the heat source inlet of the primary air heater 6 through a branch pipe, the heat source outlet of the primary air heater 6 is connected to the return pipe, and the return pipe is provided with a second electric regulating valve 35 and a third electric shut-off valve 36;

[0024] The primary fan air supply pipe 1 is connected to the air inlet of the primary air heater 6, the air outlet of the primary air heater 6 is connected to the air preheater 9 through the air preheater inlet primary air pipe 8, and the air preheater 9 is connected to the furnace of the boiler 12 through the air preheater outlet primary air pipe 10; the primary fan 4 is arranged on the primary fan air supply pipe 1;

[0025] The secondary air duct 2 at the air blower inlet is connected to the air inlet of the secondary air heater 5, the air outlet of the secondary air heater 5 is connected to the air preheater 9 through the air preheater inlet secondary air duct 7, and the air preheater 9 is connected to the furnace of the boiler 12 through the air preheater outlet secondary air duct 11; the air blower 3 is provided on the secondary air duct 2 at the air blower inlet.

[0026] The outlet pipe to be heated of the low-temperature economizer 15 is connected to the heat source inlet of the secondary air heater 5 through a branch pipe, and the heat source outlet of the secondary air heater 5 is connected to the return pipe.

[0027] The outlet pipe to be heated of the low-temperature economizer 15 is provided with a first return pipe, and the first return pipe is provided with a third electric regulating valve 33 and a fourth electric shut-off valve 34. The outlet pipe of the medium to be heated of the flue gas cooler 18 is provided with a second return pipe, and the second flow pipe is provided with a fourth electric regulating valve 31 and a fifth electric shut-off valve 32.

[0028] The steps of the heating method are as follows:

[0029] The primary air and the secondary air are heated by the primary air heater 6 and the secondary air heater 5 respectively and become the primary air 8 and the secondary air 7 at the air preheater inlet. The primary air 8 and the secondary air 7 at the air preheater inlet are further heated by the air preheater 9 and become the primary air and the secondary air at the air preheater outlet. The primary air and the secondary air at the air preheater outlet are finally sent to the furnace of the boiler 12 to participate in combustion; the low-temperature economizer 15 arranged in the horizontal flue between the air preheater 9 and the dust collector 16 absorbs the heat of the flue gas 14 at the inlet of the low-temperature economizer, and the high-temperature flue gas enters the dust collector 16 after cooling; the flue gas cooler 18 arranged between the induced draft fan 17 and the desulfurization tower 19 absorbs the temperature rise of the induced draft fan 17 and the heat of the high-temperature flue gas, and the high-temperature flue gas is cooled by the flue gas cooler 18 and becomes the low-temperature flue gas. The low-temperature flue gas is sent to the desulfurization tower 19 for desulfurization treatment and finally enters the chimney 20 and is discharged into the atmosphere;

[0030] The condensate from the steam turbine shaft seal heater 21 passing through the electric control valve 27 and the condensate from the steam turbine No. 7 low-pressure heater 22 passing through the first electric control valve 28 are mixed, and then pass through the first electric shut-off valve 29, the condensate booster pump 30, the flue gas cooler 18, the low-temperature economizer 15, the primary air heater 6 and the secondary air heater 5, the second electric control valve 35, and the third electric shut-off valve 36 in sequence to return to the higher-level low-pressure heater on the steam turbine side, such as the inlet of the steam turbine No. 5 low-pressure heater, to discharge the steam of the steam turbine to do work and improve the efficiency of the steam turbine.

[0031] The condensed water absorbs heat in the flue gas cooler 18 and the low-temperature economizer 15 to increase the temperature, and releases heat in the primary air heater 6 and the secondary air heater 5 to lower the temperature; under the action of the flue gas cooler 18 and the low-temperature economizer 15, the condensed water converts the heat from the main flue gas and the heat from the air pressure temperature rise of the induced draft fan into heat for the primary air heater 6 and the secondary air heater 5 to heat the primary air and the secondary air respectively.

[0032] When the system is put into operation, the second electric shut-off valve 27 and the first electric shut-off valve 28 are opened, and the electric shut-off valve on one of the three drainage lines is selected according to the actual operation requirements of the unit, and then the opening of the first electric regulating valve 29 and the electric regulating valve in the drainage line is adjusted.

[0033] According to the actual operation requirements of the unit, the flow of condensate water can be adjusted by automatically changing the opening of the first electric regulating valve 29, adjusting the heat exchange capacity of each heat exchanger, and thus adjusting the operation of the system.

[0034] The above-mentioned embodiments are only illustrative of the principles and effects of the invention, as well as some embodiments of its application, and are not intended to limit the invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the invention, and all of these belong to the protection scope of the invention.

Claims

1. A heat-adjustable flue gas waste heat recovery system for a coal-fired power generation unit, comprising a shaft seal heater (21), a steam turbine No. 7 low-pressure heater (22), a steam turbine No. 6 low-pressure heater (23), a steam turbine No. 5 low-pressure heater (24), a deaerator (25), and a steam turbine No. 3 high-pressure heater (26) which are sequentially connected to the steam turbine through a pipeline; Features: A first liquid outlet branch pipe is provided on the pipeline at the inlet of the shaft seal heater (21), and a first electric shut-off valve (28) and a first electric regulating valve (29) are provided on the first liquid outlet branch pipe; a second liquid outlet branch pipe is provided on the pipeline between the steam turbine No. 7 low-pressure heater (22) and the steam turbine No. 6 low-pressure heater (23), and a second electric shut-off valve (27) is provided on the second liquid outlet branch pipe; the first liquid outlet branch pipe and the second liquid outlet branch pipe are both connected to a liquid outlet main pipe, and a condensate booster pump (30) is provided on the liquid outlet main pipe; The flue gas outlet of the furnace of the boiler (12) is connected to the SCR denitration device (13), the air preheater (9), the low-temperature economizer (15), the dust collector (16), the induced draft fan (17), the flue gas cooler (18), the desulfurization tower (19), and the chimney (20) in sequence through pipelines; the liquid outlet main pipe is connected to the inlet pipe of the medium to be heated of the flue gas cooler (18); the outlet pipe of the medium to be heated of the flue gas cooler (18) is connected to the inlet pipe of the medium to be heated of the low-temperature economizer (15); the outlet pipe to be heated of the low-temperature economizer (15) is connected to the heat source inlet of the primary air heater (6) through a branch pipe; the heat source outlet of the primary air heater (6) is connected to the return pipe, and the return pipe is provided with a second electric regulating valve (35) and a third electric shut-off valve (36); The primary fan air supply pipe (1) is connected to the air inlet of the primary air heater (6); the air outlet of the primary air heater (6) is connected to the air preheater (9) through the air preheater inlet primary air pipe (8); the air preheater (9) is connected to the furnace of the boiler (12) through the air preheater outlet primary air pipe (10); and a primary fan (4) is provided on the primary fan air supply pipe (1).

2. The heat-adjustable flue gas waste heat recovery system for a coal-fired power generation unit according to claim 1, characterized in that: The secondary air duct (2) at the inlet of the blower is connected to the air inlet of the secondary air heater (5); the air outlet of the secondary air heater (5) is connected to the air preheater (9) through the secondary air duct (7) at the inlet of the air preheater; the air preheater (9) is connected to the furnace of the boiler (12) through the secondary air duct (11) at the outlet of the air preheater; and a blower (3) is provided on the secondary air duct (2) at the inlet of the blower.

3. The heat-adjustable flue gas waste heat recovery system for a coal-fired power generation unit according to claim 1, characterized in that: The outlet pipe to be heated of the low-temperature economizer (15) is connected to the heat source inlet of the secondary air heater (5) through a branch pipe, and the heat source outlet of the secondary air heater (5) is connected to the return pipe.

4. The heat-adjustable flue gas waste heat recovery system for a coal-fired power generation unit according to claim 1, characterized in that: A first return pipe is provided on the outlet pipe to be heated of the low-temperature economizer (15), and a third electric regulating valve (33) and a fourth electric shut-off valve (34) are provided on the first return pipe.

5. The heat-adjustable flue gas waste heat recovery system for a coal-fired power generation unit according to claim 1, characterized in that: A second reflux pipe is provided on the outlet pipe of the medium to be heated of the flue gas cooler (18), and a fourth electric regulating valve (31) and a fifth electric shut-off valve (32) are provided on the second flow pipe.

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