Flue gas waste heat comprehensive utilization system of coal-fired thermal power generating unit

Abstract

The utility model discloses a flue gas waste heat comprehensive utilization system of a coal-fired thermal power generating unit. The flue gas waste heat comprehensive utilization system comprises an air heater, an air preheater, a low-temperature economizer, a flue gas heat exchanger, a desulfurizing tower and a chimney, the steam turbine is provided with a first conveying pipe connected with a port in one end of a heating pipe of the condensed water-heat medium water heat exchanger. The steam turbine is provided with a second conveying pipe connected with a port of the other end of the heating pipe of the condensed water-heat medium water heat exchanger. A downstream booster pump is arranged on the second conveying pipe; counter-flow pipes provided with counter-flow booster pumps are connected in parallel with the two ends of the down-flow booster pump on the second conveying pipe; a heating medium water inlet of the condensed water-heating medium water heat exchanger is connected with a heating medium water outlet of the low-temperature economizer; a heating medium water inlet of the low-temperature economizer is connected with a heating medium water outlet connected with the flue gas heat exchanger; a heating medium water outlet of the condensed water-heating medium water heat exchanger is connected with a heating medium water inlet of the air heater, and a heating medium water outlet of the air heater is connected with a heating medium water inlet connected with the smoke heat exchanger.

Description

Technical Field

[0001] The utility model relates to a comprehensive utilization system of flue gas waste heat of a coal-fired thermal power unit, belonging to the technical field of energy-saving of coal-fired boilers. Background Art

[0002] my country's industrial sector accounts for about 70% of the country's total energy consumption, and the average unit energy consumption of major industrial products is about 30% higher than the international advanced level. In addition to relatively backward production technology and unreasonable industrial structure, low utilization rate of industrial waste heat and insufficient comprehensive utilization of energy are another important reason for high energy consumption.

[0003] In order to reduce coal consumption and improve economic efficiency of coal-fired power units, it is necessary to utilize the waste heat of the units as much as possible. The compressed air of the power plant, from the cold air through the air compressor to the gas storage tank, has a large amount of waste heat caused by the temperature rise of the air compressor. This part of the heat is huge. Recycling this part of waste heat can not only improve the efficiency of coal utilization and reduce coal consumption, but also reduce the production cost of enterprises, which is of great significance to promoting the realization of carbon peak and carbon neutrality goals as scheduled. Utility Model Content

[0004] The technical problem to be solved by the utility model is to provide a comprehensive utilization system of flue gas waste heat of coal-fired thermal power generation units.

[0005] In order to solve the above technical problems, the technical solution adopted by the utility model is: a comprehensive utilization system of flue gas waste heat of coal-fired thermal power units, including a heater, an air preheater with a furnace flue gas conveying pipe connected to the flue gas inlet; a heater inlet air duct and a heater outlet air duct are connected to the heater; the heater outlet air duct is connected to the inlet of the medium to be heated of the air preheater, and the outlet air duct of the air preheater is provided at the outlet of the medium to be heated on the air preheater;

[0006] An air preheater outlet flue gas pipe is provided on the flue gas outlet of the air preheater; the air preheater outlet flue gas pipe is connected to the flue gas inlet of the low-temperature economizer; the flue gas outlet of the low-temperature economizer is connected to the flue gas heat exchanger, the desulfurization tower and the chimney in sequence through the flue;

[0007] The inlet of the No. 9 low-pressure heater of the steam turbine is provided with a No. 9 low-pressure heater inlet condensate pipe; the No. 9 low-pressure heater; the No. 8 low-pressure heater; the No. 7 low-pressure heater; the No. 6 low-pressure heater; the outlet of the No. 6 low-pressure heater is provided with a No. 6 low-pressure heater outlet condensate pipe;

[0008] A first delivery pipe connected to one end of a heating pipe of a condensate-heat medium water heat exchanger is provided on the pipeline between the No. 7 low-pressure heater and the No. 6 low-pressure heater of the steam turbine;

[0009] A second delivery pipe connected to the other end port of the heating pipe of the condensate-heat medium water heat exchanger is provided on the pipeline between the No. 9 low-pressure heater and the No. 8 low-pressure heater of the steam turbine; a downstream booster pump is provided on the second delivery pipe; a countercurrent pipe with a countercurrent booster pump is connected in parallel at both ends of the downstream booster pump on the second delivery pipe; the countercurrent booster pump and the downstream booster pump do not work at the same time and have opposite pumping directions;

[0010] The heat medium water inlet of the condensate-heat medium water heat exchanger is connected to the heat medium water outlet of the low-temperature economizer through the heat medium water pipe at the outlet of the low-temperature economizer; the heat medium water inlet of the low-temperature economizer is connected to the heat medium water outlet connected to the flue gas heat exchanger through the heat medium water pipe at the outlet of the flue gas heat exchanger; the heat medium water outlet of the condensate-heat medium water heat exchanger is connected to the heat medium water inlet of the heater through the heat medium water pipe at the inlet of the heater, and the heat medium water outlet of the heater is connected to the heat medium water inlet connected to the flue gas heat exchanger through the heat medium water pipe at the inlet of the flue gas heat exchanger.

[0011] As a preferred solution, a heat medium water delivery pump is provided on the heat medium water pipe at the inlet of the flue gas heat exchanger.

[0012] As a preferred solution, a dust collector and an induced draft fan are sequentially provided on the flue between the low-temperature economizer and the flue gas heat exchanger along the flue gas conveying direction.

[0013] As a preferred solution, the air heater, flue gas heat exchanger and low-temperature economizer all adopt counter-flow heat exchangers.

[0014] As a preferred solution, the flue gas heat exchanger is a heat exchanger using spirally formed fins.

[0015] The beneficial effects of the utility model are:

[0016] The present invention recovers the waste heat of the clean flue gas at the outlet of the desulfurization tower to heat the cold air entering the air preheater and to displace the steam extracted from the low-pressure heater of the steam turbine, thereby increasing the temperature of the hot air entering the boiler and improving the efficiency of the steam turbine. Increasing the temperature of the hot air entering the boiler can improve the combustion stability and the burnout of coal powder in the boiler, and is also conducive to improving the combustion efficiency of the boiler and improving the economy. In addition, compared with the conventional flue gas waste heat utilization system, this solution does not use a steam heater, reduces the consumption of high-quality steam, and has better energy-saving benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a block diagram of the system composition of the present invention.

[0018] In the figure: heater inlet duct (1); heater (2); heater outlet duct (3); air preheater (4); air preheater outlet duct (5); furnace flue gas delivery pipe (6); air preheater outlet flue gas pipe (7); low-temperature economizer (8); dust collector (9); induced draft fan (10); flue gas heat exchanger (11); desulfurization tower (12); chimney (13); No. 9 low-pressure heater inlet condensate pipe (14); No. 9 low-pressure heater (15); No. 8 low No. 6 low-pressure heater (18); No. 6 low-pressure heater outlet condensate pipe (19); countercurrent booster pump (20); downstream booster pump (21); condensate-heat medium water heat exchanger (22); flue gas heat exchanger inlet heat medium water pipe (23); flue gas heat exchanger outlet heat medium water pipe (24); low-temperature economizer outlet heat medium water pipe (25); heater inlet heat medium water pipe (26); (27) heater outlet heat medium water pipe. 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 comprehensive utilization system of flue gas waste heat of a coal-fired thermal power unit comprises a heater 2, an air preheater 4 whose flue gas inlet is connected to a furnace flue gas conveying pipe 6; a heater inlet air duct 1 and a heater outlet air duct 3 are connected to the heater 2; the heater outlet air duct 3 is connected to the inlet of a medium to be heated of the air preheater 4, and an air preheater outlet air duct 5 is provided at the outlet of the medium to be heated on the air preheater 4;

[0021] An air preheater outlet flue gas pipe 7 is provided at the flue gas outlet of the air preheater 4; the air preheater outlet flue gas pipe 7 is connected to the flue gas inlet of the low-temperature economizer 8; the flue gas outlet of the low-temperature economizer 8 is connected to the dust collector 9, the induced draft fan 10, the flue gas heat exchanger 11, the desulfurization tower 12, and the chimney 13 in sequence through the flue;

[0022] The inlet of the No. 9 low-pressure heater 15 of the steam turbine is provided with a No. 9 low-pressure heater inlet condensate pipe 14; the outlets of the No. 9 low-pressure heater 15, the No. 8 low-pressure heater 16, the No. 7 low-pressure heater 17, the No. 6 low-pressure heater 18, and the No. 6 low-pressure heater 18 are connected in sequence through pipelines and provided with a No. 6 low-pressure heater outlet condensate pipe 19;

[0023] A first delivery pipe connected to one end of the heating pipe of the condensate-heat medium water heat exchanger 22 is provided on the pipeline between the No. 7 low-pressure heater 17 and the No. 6 low-pressure heater 18 of the steam turbine;

[0024] A second delivery pipe connected to the other end port of the heating pipe of the condensate-heat medium water heat exchanger 22 is provided on the pipeline between the No. 9 low-pressure heater 15 and the No. 8 low-pressure heater 16 of the steam turbine; a downstream booster pump 21 is provided on the second delivery pipe; a countercurrent pipe with a countercurrent booster pump 20 is connected in parallel at both ends of the downstream booster pump 21 on the second delivery pipe; the countercurrent booster pump 20 and the downstream booster pump 21 do not work at the same time and have opposite pumping directions;

[0025] The heat medium water inlet of the condensate-heat medium water heat exchanger 22 is connected to the heat medium water outlet of the low-temperature economizer 8 through the low-temperature economizer outlet heat medium water pipe 25; the heat medium water inlet of the low-temperature economizer 8 is connected to the heat medium water outlet connected to the flue gas heat exchanger 11 through the flue gas heat exchanger outlet heat medium water pipe 24; the heat medium water outlet of the condensate-heat medium water heat exchanger 22 is connected to the heat medium water inlet of the heater 2 through the heater inlet heat medium water pipe 26, and the heat medium water outlet of the heater 2 is connected to the heat medium water inlet connected to the flue gas heat exchanger 11 through the flue gas heat exchanger inlet heat medium water pipe 23. A heat medium water delivery pump 27 is provided on the flue gas heat exchanger inlet heat medium water pipe 23.

[0026] The air heater 2, the flue gas heat exchanger 11 and the low-temperature economizer 8 are all counter-flow heat exchangers, wherein the flue gas heat exchanger 11 is a heat exchanger using spiral fins.

[0027] The steps of the heating method are as follows:

[0028] The heater inlet air is heated by the heater 2 and becomes the heater outlet air, and the heater outlet air is further heated by the air preheater 4 and becomes the air preheater outlet air. The primary and secondary air at the air preheater outlet are finally sent to the boiler furnace to participate in combustion; the furnace flue gas passes through the air preheater 4, the low-temperature economizer 8, the dust collector 9, the induced draft fan 10, the flue gas heat exchanger 11, and the desulfurization tower 12 in sequence, and is finally discharged into the atmosphere through the chimney 13; the low-temperature economizer 8 arranged in the horizontal flue between the air preheater 4 and the dust collector 9 absorbs the heat of the flue gas at the air preheater outlet, and the high-temperature flue gas enters the dust collector 9 after cooling; the flue gas heat exchanger 11 arranged between the induced draft fan 10 and the desulfurization tower 12 absorbs the temperature rise of the induced draft fan 10 and the heat of the high-temperature flue gas, and the high-temperature flue gas is cooled by the flue gas heat exchanger 11 and becomes low-temperature flue gas, and the low-temperature flue gas goes to the desulfurization tower 12 for desulfurization treatment;

[0029] The high-temperature heat medium water in the heater import releases heat in the heater 2 for the first cooling and then goes to the flue gas heat exchanger 11, absorbs heat in the flue gas heat exchanger 11 for the first heating and then goes to the low-temperature economizer 8, absorbs heat in the low-temperature economizer 8 for the second heating and then goes to the condensate-heat medium water heat exchanger 22. To maintain heat balance, the condensate-heat medium water heat exchanger 22 releases heat for the second cooling in summer, and absorbs heat in the condensate-heat medium water heat exchanger 22 for the third heating in winter, and finally goes to the heater 2 to complete the cycle;

[0030] In summer, the countercurrent booster pump 20 is started, the downstream booster pump 21 is shut down, and the condensate pipe takes water from the inlet of the No. 8 low-pressure heater 16. The heat absorbed by the low-temperature economizer 8 and the flue gas heat exchanger 11 is greater than the heat required to be absorbed by the heater 2. After the condensate-heat medium water heat exchanger 22 and the heat medium water are countercurrently heated and heated, the condensate returns to the outlet of the No. 7 low-pressure heater 17 on the steam turbine side, and the low-temperature condensate pipe at the inlet of the No. 8 low-pressure heater 17 is used to absorb excess heat and recover the waste heat of the flue gas.

[0031] In winter, the countercurrent booster pump 20 is turned off and the downstream booster pump 21 is started. The condensate pipe takes water from the outlet of the No. 7 low-pressure heater 17, and uses the high-temperature condensate pipe at the outlet of the No. 7 low-pressure heater 17 to supplement heat; after the condensate-heat medium water heat exchanger 22 exchanges heat with the heat medium water in the downstream and cools it down, it returns to the inlet of the No. 8 low-pressure heater 16 on the steam turbine side.

[0032] 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 system for comprehensively utilizing waste heat from flue gas of a coal-fired power plant, comprising a heater (2), an air preheater (4) having a flue gas inlet connected to a furnace flue gas delivery pipe (6); a heater inlet air duct (1) and a heater outlet air duct (3) connected to the heater (2); the heater outlet air duct (3) is connected to an inlet of a medium to be heated of the air preheater (4), and an air preheater outlet air duct (5) is provided at an outlet of the medium to be heated on the air preheater (4); An air preheater outlet flue gas pipe (7) is provided at the flue gas outlet of the air preheater (4); the air preheater outlet flue gas pipe (7) is connected to the flue gas inlet of the low-temperature economizer (8); the flue gas outlet of the low-temperature economizer (8) is connected to the flue gas heat exchanger (11), the desulfurization tower (12), and the chimney (13) in sequence through the flue; The inlet of the No. 9 low-pressure heater (15) of the steam turbine is provided with a No. 9 low-pressure heater inlet condensate pipe (14); the No. 9 low-pressure heater (15), the No. 8 low-pressure heater (16), the No. 7 low-pressure heater (17), the No. 6 low-pressure heater (18) are sequentially connected through pipelines, and the outlet of the No. 6 low-pressure heater (18) is provided with a No. 6 low-pressure heater outlet condensate pipe (19); Features: A first delivery pipe connected to one end of a heating pipe of a condensate-heat medium water heat exchanger (22) is provided on the pipeline between the No. 7 low-pressure heater (17) and the No. 6 low-pressure heater (18) of the steam turbine; A second delivery pipe connected to the other end port of the heating pipe of the condensate-heat medium water heat exchanger (22) is provided on the pipeline between the No. 9 low-pressure heater (15) and the No. 8 low-pressure heater (16) of the steam turbine; a downstream booster pump (21) is provided on the second delivery pipe; a countercurrent pipe with a countercurrent booster pump (20) is connected in parallel at both ends of the downstream booster pump (21) on the second delivery pipe; the countercurrent booster pump (20) and the downstream booster pump (21) do not work at the same time and have opposite pumping directions; The heat medium water inlet of the condensate-heat medium water heat exchanger (22) is connected to the heat medium water outlet of the low-temperature economizer (8) through the low-temperature economizer outlet heat medium water pipe (25); the heat medium water inlet of the low-temperature economizer (8) is connected to the heat medium water outlet connected to the flue gas heat exchanger (11) through the flue gas heat exchanger outlet heat medium water pipe (24); the heat medium water outlet of the condensate-heat medium water heat exchanger (22) is connected to the heat medium water inlet of the heater (2) through the heater inlet heat medium water pipe (26), and the heat medium water outlet of the heater (2) is connected to the heat medium water inlet connected to the flue gas heat exchanger (11) through the flue gas heat exchanger inlet heat medium water pipe (23).

2. A system for comprehensive utilization of flue gas waste heat from a coal-fired power plant as claimed in claim 1, characterized in that: A heat medium water delivery pump (27) is provided on the heat medium water pipe (23) at the inlet of the flue gas heat exchanger.

3. A system for comprehensive utilization of flue gas waste heat from a coal-fired power plant as claimed in claim 1, characterized in that: A dust collector (9) and an induced draft fan (10) are arranged in sequence on the flue between the low-temperature economizer (8) and the flue gas heat exchanger (11) along the flue gas conveying direction.

4. A system for comprehensive utilization of flue gas waste heat from a coal-fired power plant as claimed in any one of claims 1 to 3, characterized in that: The air heater (2), flue gas heat exchanger (11) and low-temperature economizer (8) all adopt counter-flow heat exchangers.

5. A system for comprehensive utilization of flue gas waste heat from a coal-fired power plant as claimed in claim 4, characterized in that: The flue gas heat exchanger (11) is a heat exchanger using spirally formed fins.

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