CN214370115U - Waste heat cascade utilization system for coal-fired flue gas - Google Patents
Waste heat cascade utilization system for coal-fired flue gas Download PDFInfo
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- CN214370115U CN214370115U CN202023225397.4U CN202023225397U CN214370115U CN 214370115 U CN214370115 U CN 214370115U CN 202023225397 U CN202023225397 U CN 202023225397U CN 214370115 U CN214370115 U CN 214370115U
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Abstract
A waste heat cascade utilization system for coal-fired flue gas comprises a boiler and a chimney, wherein the boiler and the chimney are communicated with a flue, and an economizer, an air preheater, a dust remover, a primary heat exchanger, a secondary heat exchanger, an induced draft fan and an absorption tower are sequentially arranged in the flue; the system also comprises an air heat exchanger, a water feeding pump, a circulating water pump and a blower; the water inlet end and the water outlet end of the economizer are respectively connected with a water feeding pump and a boiler; the water inlet end of the primary heat exchanger is respectively connected with the water feed pump and the water outlet end of the air heat exchanger, and the water outlet end of the primary heat exchanger is respectively connected with the water inlet ends of the economizer and the air heat exchanger; the water inlet end and the water outlet end of the air heat exchanger are respectively connected with the water inlet end and the water outlet end of the primary heat exchanger, and the air inlet end and the air outlet end of the air heat exchanger are respectively connected with a blower and an air preheater; the air inlet end and the air outlet end of the air preheater are respectively connected with the air outlet end of the air heat exchanger and the boiler; the water inlet end of the secondary heat exchanger is connected with a water feeding pump, and the water outlet end of the secondary heat exchanger is respectively connected with the coal economizer and the water inlet end of the primary heat exchanger. The waste heat cascade utilization system can carry out cascade utilization on the waste heat of the flue gas.
Description
Technical Field
The utility model belongs to boiler combustion field, concretely relates to waste heat cascade utilization system for coal-fired flue gas.
Background
The flue gas temperature of the tail flue of the pulverized coal industrial boiler is higher and is mostly within the range of 120-. The scheme that current pulverized coal boiler waste heat recovery mainly adopted two-stage flue gas waste heat recovery, set up flue gas waste heat recovery device before dust remover and desulfurizing tower respectively promptly, though can reduce the exhaust gas temperature of boiler, the reduction range is little, can not carry out the cascade utilization to the flue gas waste heat according to the operating condition of boiler during waste heat utilization simultaneously, can not make full use of flue gas waste heat.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a waste heat cascade utilization system for coal-fired flue gas, this waste heat cascade utilization system simple structure can carry out cascade utilization, make full use of flue gas waste heat to the flue gas waste heat.
In order to realize the purpose of the utility model, the following technical scheme is adopted:
a waste heat cascade utilization system for coal-fired flue gas comprises a boiler and a chimney which are communicated through a flue, wherein an economizer, an air preheater, a dust remover, a primary heat exchanger, a secondary heat exchanger, an induced draft fan and an absorption tower are sequentially arranged in the flue and are used for sequentially processing the flue gas from the boiler so as to exhaust from the chimney;
the waste heat cascade utilization system also comprises an air heat exchanger, a water feeding pump, a circulating water pump and a blower;
the water inlet end of the economizer is connected to the feed water pump, the water outlet end of the economizer is connected to the boiler, and the economizer is used for heating water from the feed water pump by using waste heat of flue gas from the boiler so as to supply the water to the boiler;
the water inlet end of the primary heat exchanger is respectively connected to the water outlet ends of the water feeding pump and the air heat exchanger, and the water outlet end of the primary heat exchanger is respectively connected to the water inlet end of the economizer and the water inlet end of the air heat exchanger and used for heating water from the water feeding pump and/or the air heat exchanger by using waste heat of flue gas from the dust remover so as to supply the water to the economizer and/or the air heat exchanger; the circulating water pump is arranged on a pipeline from the water outlet end of the primary heat exchanger to the water inlet end of the air heat exchanger;
the water inlet end of the air heat exchanger is connected to the water outlet end of the primary heat exchanger through the circulating water pump, the water outlet end of the air heat exchanger is connected to the water inlet end of the primary heat exchanger, the air inlet end of the air heat exchanger is connected to the blower, and the air outlet end of the air heat exchanger is connected to the air preheater and used for circularly utilizing water from the primary heat exchanger to heat air from the blower so as to supply the air preheater;
the air inlet end of the air preheater is connected to the air outlet end of the air heat exchanger, the air outlet end of the air preheater is connected to the boiler, and the air preheater is used for heating the air from the air heat exchanger by using the waste heat of the flue gas from the economizer so as to supply the air to the boiler as primary air;
the water inlet end of the secondary heat exchanger is connected to the water feeding pump, the water outlet end of the secondary heat exchanger is connected to the water inlet end of the economizer, and the secondary heat exchanger is used for heating water from the water feeding pump by using the waste heat of the flue gas from the primary heat exchanger so as to supply the water to the economizer;
the water outlet end of the secondary heat exchanger is also connected to the water inlet end of the primary heat exchanger, and the water outlet end of the secondary heat exchanger is used for heating water from the secondary heat exchanger by using the waste heat of the flue gas from the dust remover in the primary heat exchanger so as to supply the water to the economizer and/or the air heat exchanger.
Preferably, a first valve is arranged on a first pipeline from the feed water pump to the economizer and used for opening/closing to communicate/block the water inlet of the feed water pump to the economizer.
Preferably, the water inlet end of the secondary heat exchanger is provided with a second valve for opening/closing to communicate/block the water inlet of the feed water pump to the secondary heat exchanger.
Preferably, the water outlet end of the secondary heat exchanger is provided with a third valve for opening/closing to communicate/block the water inlet of the secondary heat exchanger to the economizer.
Preferably, the water inlet end and the water outlet end of the secondary heat exchanger are respectively connected to the first pipeline and are respectively positioned at the water inlet end and the water outlet end of the first valve; the second valve is arranged on a third pipeline from the water inlet end of the first valve to the water inlet end of the secondary heat exchanger; the third valve is arranged on a fourth pipeline from the water outlet end of the secondary heat exchanger to the water outlet end of the first valve.
Preferably, a fourth valve is arranged at the water inlet end of the circulating water pump and used for opening/closing to communicate/block water inlet of the primary heat exchanger to the air heat exchanger.
Preferably, the water outlet end of the air heat exchanger is provided with a fifth valve for opening/closing to communicate/block the water inlet of the air heat exchanger to the primary heat exchanger.
Preferably, a sixth valve is arranged on a second pipeline from the water outlet end of the secondary heat exchanger to the water inlet end of the primary heat exchanger, and is used for opening/closing to communicate/block the water inlet of the secondary heat exchanger to the primary heat exchanger; and two ends of the second pipeline are respectively connected to the water inlet end of the third valve and the water outlet end of the fifth valve.
Preferably, a fifth pipeline from the water outlet end of the second valve to the water outlet end of the sixth valve is provided with a seventh valve, and the seventh valve and the second valve are opened/closed simultaneously to communicate/block the water inlet of the feed water pump to the primary heat exchanger.
Preferably, an eighth valve is arranged on a sixth pipeline from the water outlet end of the primary heat exchanger to the water inlet end of the economizer; the water inlet end of the eighth valve is connected to the water inlet end of the fourth valve, and the water outlet end of the eighth valve is connected to the water outlet end of the first valve and used for being opened/closed to communicate/block the water inlet of the primary heat exchanger to the economizer.
The beneficial effects of the utility model reside in that:
the utility model discloses a waste heat cascade utilization system for coal-fired flue gas, simple structure can adjust the waste heat utilization mode in a flexible way, carries out cascade utilization, make full use of flue gas waste heat to the flue gas waste heat.
Drawings
Fig. 1 is a schematic structural diagram of a waste heat cascade utilization system for coal-fired flue gas according to an embodiment of the present invention.
Detailed Description
The technical solution and effects of the present invention will be further explained with reference to the accompanying drawings and the detailed description. The following embodiments are merely illustrative of the present invention, and the present invention is not limited to the following embodiments or examples. Use the utility model discloses a think about right the utility model discloses the simple change that goes on is all in the utility model discloses the within range that claims.
As shown in fig. 1, the utility model provides a waste heat cascade utilization system for coal-fired flue gas, including boiler and chimney 1 that are linked together through the flue, economizer 2, air heater 3, dust remover 4, primary heat exchanger 5, secondary heat exchanger 6, draught fan 7 and absorption tower 8 have set gradually in the flue, be used for handling the flue gas that comes from the boiler in proper order with from the evacuation of chimney 1;
the waste heat cascade utilization system also comprises an air heat exchanger 9, a water feed pump 10, a circulating water pump 11 and a blower 12;
the water inlet end of the economizer 2 is connected to the feed water pump 10, and the water outlet end of the economizer is connected to the boiler, and the economizer is used for heating water from the feed water pump 10 by using the waste heat of flue gas from the boiler so as to supply the water to the boiler;
the water inlet end of the primary heat exchanger 5 is respectively connected to the water outlet ends of the water feed pump 10 and the air heat exchanger 9, and the water outlet end of the primary heat exchanger 5 is respectively connected to the water inlet end of the economizer 2 and the water inlet end of the air heat exchanger 9, so that the water from the water feed pump 10 and/or the water from the air heat exchanger 9 can be heated by using the waste heat of the flue gas from the dust remover 4 to be supplied to the economizer 2 and/or the air heat exchanger 9; the circulating water pump 11 is arranged on a pipeline from the water outlet end of the primary heat exchanger 5 to the water inlet end of the air heat exchanger 9;
the water inlet end of the air heat exchanger 9 is connected to the water outlet end of the primary heat exchanger 5 through the circulating water pump 11, the water outlet end of the air heat exchanger 9 is connected to the water inlet end of the primary heat exchanger 5, the air inlet end of the air heat exchanger 9 is connected to the blower (12), and the air outlet end of the air heat exchanger 9 is connected to the air preheater 3 and is used for circularly heating the air from the blower 12 by using the water from the primary heat exchanger 5 to supply the air preheater 3;
the air preheater has an air inlet end connected to the air outlet end of the air heat exchanger 9, the air outlet end of the air preheater 3 is connected to the boiler, and is used for utilizing the flue gas waste heat from the economizer 2 to connect the water inlet end of the primary heat exchanger 5 of the air heat exchanger 9 to the water outlet end of the water feed pump 10 and the air heat exchanger 9 respectively, and the water outlet end of the primary heat exchanger 5 is connected to the water inlet end of the economizer 2 and the water inlet end of the air heat exchanger 9 respectively, and is used for utilizing the flue gas waste heat from the dust remover 4 to heat the water from the water feed pump 10 and/or the air heat exchanger 9 so as to supply the water to the economizer 2 and/or the air heat exchanger 9; the circulating water pump 11 is arranged on a pipeline from the water outlet end of the primary heat exchanger 5 to the water inlet end of the air heat exchanger 9;
the water inlet end of the air heat exchanger 9 is connected to the water outlet end of the primary heat exchanger 5 through the circulating water pump 11, the water outlet end of the air heat exchanger 9 is connected to the water inlet end of the primary heat exchanger 5, the air inlet end of the air heat exchanger 9 is connected to the blower 12, and the air outlet end of the air heat exchanger 9 is connected to the air preheater 3 and is used for circularly heating the air from the blower 12 by using the water from the primary heat exchanger 5 to supply the air preheater 3;
the air inlet end of the air preheater 3 is connected to the air outlet end of the air heat exchanger 9, the air outlet end of the air preheater 3 is connected to the boiler, and the air from the air heat exchanger 9 is heated by using the flue gas waste heat from the economizer 2 to be supplied to the boiler as primary air;
the water inlet end of the secondary heat exchanger 6 is connected to the water feeding pump 10, and the water outlet end of the secondary heat exchanger is connected to the water inlet end of the economizer 2, so that the water from the water feeding pump 10 is heated by using the waste heat of the flue gas from the primary heat exchanger 5 to be supplied to the economizer 2;
the water outlet end of the secondary heat exchanger 6 is also connected to the water inlet end of the primary heat exchanger 5, and is used for heating water from the secondary heat exchanger 6 in the primary heat exchanger 5 by using the flue gas waste heat from the dust remover 4 so as to supply the water to the economizer 2 and/or the air heat exchanger 9;
the water inlet end of the secondary heat exchanger 6 is connected to the water feeding pump 10, and the water outlet end of the secondary heat exchanger is connected to the water inlet end of the economizer 2, so that the water from the water feeding pump 10 is heated by using the waste heat of the flue gas from the primary heat exchanger 5 to be supplied to the economizer 2;
the water outlet end of the secondary heat exchanger 6 is also connected to the water inlet end of the primary heat exchanger 5, and is used for heating the water from the secondary heat exchanger 6 in the primary heat exchanger 5 by using the flue gas waste heat from the dust remover 4 so as to supply the water to the economizer 2 and/or the air heat exchanger 9.
The technical personnel in the field understand, economizer 2 be used for to the boiler provides hot water, air heater 3 is used for right economizer 2 goes out the flue gas of cigarette end and carries out the heat transfer cooling, dust remover 4 is used for right air heater 3 goes out the flue gas of cigarette end and removes dust, one-level heat exchanger 5 is used for right the flue gas that dust remover 4 goes out the cigarette end carries out the heat transfer cooling, second grade heat exchanger 6 is used for right the flue gas that one-level heat exchanger 5 goes out the cigarette end carries out the heat transfer cooling, draught fan 7 is used for leading to the flue gas after the cooling the absorption tower 8 carries out the desulfurization, chimney 1 is used for the flue gas evacuation after the desulfurization. The primary air is air fed into a hearth of the boiler for combustion.
The utility model discloses a waste heat cascade utilization system for coal-fired flue gas, simple structure can carry out cascade utilization, make full use of flue gas waste heat to the flue gas waste heat. On one hand, when the boiler works by using coal with poor ignition conditions, the waste heat of the flue gas at the smoke outlet end of the dust remover 4 can be used in the primary heat exchanger 5 to heat the water inlet (comprising the water from the water feed pump 10, the water from the water outlet end of the secondary heat exchanger 6 and the water from the water outlet end of the air heat exchanger) of the primary heat exchanger 5, and the heated water is used to heat the air entering the air heat exchanger 9, so that the temperature of the primary air entering the boiler is increased, the ignition of the low-quality coal is facilitated, the combustion stability of the boiler is enhanced, the adaptability of the low-quality coal for combustion is improved, and the temperature of the flue gas can be reduced; on the other hand, can utilize the flue gas waste heat to heat the intaking of economizer 2, in order to improve to economize the temperature of intaking of economizer 2 improves the thermal efficiency of boiler, also can restrain the regional acid condensation dewfall of economizer and then slow down acid corrosion simultaneously, reinforcing economizer equipment life realizes cyclic utilization and the cascade utilization of energy, improves the utilization efficiency of flue gas waste heat, avoids the energy waste.
As understood by the technical personnel in the field, the primary heat exchanger 5 and the secondary heat exchanger 6 can be made of fluoroplastic steel materials, can resist acid corrosion and can bear the water supply pressure of a boiler, so that the safe and stable operation of the heat exchangers is ensured.
In one embodiment, a first valve 15 is disposed on a first line from the feed water pump 10 to the economizer 2, and is opened/closed to connect/block the feed water pump 10 to the economizer 2.
In one embodiment, the water inlet end of the secondary heat exchanger 6 is provided with a second valve 16 for opening/closing to connect/block the water inlet of the feed pump 10 to the secondary heat exchanger 6.
In one embodiment, the water outlet end of the secondary heat exchanger 6 is provided with a third valve 17 for opening/closing to communicate/block the water inlet of the secondary heat exchanger 6 to the economizer 2.
In one embodiment, the water inlet and outlet ends of the secondary heat exchanger 6 are connected to the first pipeline and located at the water inlet and outlet ends of the first valve 15, respectively; the second valve 16 is arranged on a third pipeline from the water inlet end of the first valve 15 to the water inlet end of the secondary heat exchanger 6; third valve 17 set up in certainly secondary heat exchanger 6's play water end extremely on the fourth pipeline of the play water end of first valve 15, be used for through control first valve 15 second valve 16 with opening/closing of third valve 17, control feed pump 10 directly to economizer 2 is intake, perhaps earlier to secondary heat exchanger 6 is intake and is improved with utilizing the flue gas waste heat the temperature of intaking of economizer 2 improves the thermal efficiency of boiler, also can restrain the regional acid condensation dewfall of economizer and then slow down acid corrosion simultaneously, strengthens economizer equipment life, realizes cyclic utilization and the cascade utilization of energy, improves the utilization efficiency of flue gas waste heat. When the temperature of the inlet water of the economizer 2 is too high, in order to prevent the inlet water of the economizer 2 from being seriously overfull in the economizer 2 to influence the operation safety, or when the temperature of the flue gas at the smoke outlet end of the primary heat exchanger 5 is lower, the relevant valves (the second valve 16 and the third valve 17 are closed, and the first valve 15 is opened) can be adjusted, so that the water from the feed water pump 10 is directly fed into the economizer 2 without being heated by the waste heat of the flue gas of the secondary heat exchanger 6; when the flue gas temperature of 5 cigarette ends of giving out of one-level heat exchanger is higher, close first valve 15 opens second valve 16 with third valve 17, feed pump 10 earlier to second grade heat exchanger 6 is intake, in order utilize in the second grade heat exchanger 6 the flue gas waste heat of 5 cigarette ends of giving out of one-level heat exchanger improves the temperature of intaking of economizer 2 reduces the exhaust gas temperature simultaneously. In one embodiment, the water inlet end of the circulating water pump 11 is provided with a fourth valve 18 for opening/closing to communicate/block the water inlet of the primary heat exchanger 5 to the air heat exchanger 9.
In one embodiment, the water outlet end of the air heat exchanger 9 is provided with a fifth valve 19 for opening/closing to communicate/block the water inlet of the air heat exchanger 9 to the primary heat exchanger 5.
In one embodiment, a sixth valve 20 is disposed on a second pipeline from the water outlet end of the secondary heat exchanger 6 to the water inlet end of the primary heat exchanger 5, and is used for opening/closing to communicate/block the water inlet of the secondary heat exchanger 6 to the primary heat exchanger 5; both ends of the second pipeline are respectively connected to the water inlet end of the third valve 17 and the water outlet end of the fifth valve 19.
When the temperature of the water from the secondary heat exchanger 6 is low, the first valve 15 and the third valve 17 can be closed, the second valve 16, the fourth valve 18, the fifth valve 19 and the sixth valve 20 can be opened, the water from the secondary heat exchanger 6 is input into the primary heat exchanger 5 to be further heated by the residual heat of the flue gas at the smoke outlet end of the dust remover 4, and then input into the air heat exchanger 9 to be heated to be supplied to the air preheater 3, and the air from the air heat exchanger 9 is further heated by the residual heat of the flue gas at the smoke outlet end of the coal economizer 2 in the air preheater 3 to be conveyed into the boiler as primary air, so as to increase the temperature of the primary air entering the boiler, help the ignition of coal, and enhance the combustion stability of the boiler, The adaptability of burning the inferior coal is improved, and the flue gas waste heat can be further utilized, so that the cascade utilization of the flue gas waste heat is realized, the utilization efficiency of the flue gas waste heat is improved, and the flue gas temperature is reduced.
In one embodiment, a seventh valve 21 is disposed on a fifth pipeline from the water outlet end of the second valve 16 to the water outlet end of the sixth valve 20, and is used for opening/closing simultaneously with the second valve 16 to connect/block the water inlet of the feed water pump 10 to the primary heat exchanger 5.
Closing the third valve 17 and the first valve 15, and opening the second valve 16, the sixth valve 20, the seventh valve 21, the fourth valve 18 and the fifth valve 19 to allow water from the feed pump 10 to enter the primary heat exchanger 5 and the secondary heat exchanger 6, respectively; in the primary heat exchanger 5, after the flue gas waste heat at the smoke outlet end of the dust remover 4 is used for heating the water from the water feeding pump 10, the water is input into the air heat exchanger 9 for heating the air from the air blower 12 and then used as the air inlet of the air preheater 3, and then in the air preheater 3, after the flue gas waste heat at the smoke outlet end of the coal economizer 2 is used for further heating the air from the air heat exchanger 9, the air is used as primary air and sent into the boiler, so that the primary air temperature entering the boiler is improved, the coal ignition is facilitated, the combustion stability of the boiler is enhanced, the adaptability of burning inferior coal is improved, the boiler efficiency is improved, and the flue gas is subjected to gradient cooling; in the secondary heat exchanger 6, after the flue gas waste heat at the smoke outlet end of the primary heat exchanger 5 is used for heating the water from the water feeding pump 10, the water is input into the primary heat exchanger 5 again, and the previous step of increasing the primary air temperature is repeated, so that the primary air temperature is increased, the flue gas waste heat is subjected to gradient utilization, the utilization efficiency of the flue gas waste heat is improved, and the reduction of the flue gas temperature is realized.
In one embodiment, an eighth valve 13 is disposed on a sixth pipeline from the water outlet end of the primary heat exchanger 5 to the water inlet end of the economizer 2; the water inlet end of the eighth valve 13 is connected to the water inlet end of the fourth valve 18, and the water outlet end of the eighth valve 13 is connected to the water outlet end of the first valve 15, and is configured to be opened/closed to communicate/block the water inlet of the primary heat exchanger 5 to the economizer 2.
Closing the third valve 17, the first valve 15, the fourth valve 18 and the fifth valve 19, and opening the second valve 16, the sixth valve 20, the seventh valve 21 and the eighth valve 13 to allow water from the feed pump 10 to enter the primary heat exchanger 5 and the secondary heat exchanger 6, respectively; in the primary heat exchanger 5, after the flue gas waste heat at the smoke outlet end of the dust remover 4 is used for heating the water from the water feeding pump 10, the water is input into the economizer 2 so as to improve the water inlet temperature of the economizer 2; in the second grade heat exchanger 6, utilize 5 smoke waste heat that go out the cigarette end of one-level heat exchanger are to coming from behind the water heating of feed pump 10, input once more in the one-level heat exchanger 5, utilize the smoke waste heat that dust remover 4 goes out the cigarette end is to coming from behind the water heating of feed pump 10, input in 2 with the temperature of intaking that improves economizer 2 in the economizer, not only improved economizer 2's the temperature of intaking has improved the thermal efficiency of boiler, also can restrain the acid condensation dewfall in 2 regions of economizer simultaneously and then slow down the acid corrosion, and 2 equipment life of reinforcing economizer have still realized carrying out the cascade utilization to the smoke waste heat, have realized the reduction of gas temperature.
As shown in fig. 1, in an embodiment, the operation process of the waste heat cascade utilization system for coal-fired flue gas of the present invention is as follows:
the flue gas generated by the boiler is sequentially treated by an economizer 2, an air preheater 3, a dust remover 4, a primary heat exchanger 5, a secondary heat exchanger 6, an induced draft fan 7 and an absorption tower 8 in a flue and then is exhausted from the chimney 1;
when the inlet water temperature of the economizer 2 is too high, other valves can be closed, only the first valve 15 is opened, and the water from the water feeding pump 10 is directly fed into the economizer 2;
when the feed water temperature of the economizer 2 is low, the feed water temperature can be increased by adjusting relevant valves, such as: (1) closing the first valve 15 and other valves, only opening the second valve 16 and the third valve 17, feeding water from the feed water pump 10 into the secondary heat exchanger 6, heating the water in the secondary heat exchanger 6 by using the residual heat of the flue gas at the smoke outlet end of the primary heat exchanger 5, and then inputting the heated water into the economizer 2 to increase the inlet water temperature of the economizer 2; (2) closing the third valve 17, the first valve 15, the fourth valve 18, the fifth valve 19 and the seventh valve 21, opening only the second valve 16, the sixth valve 20 and the eighth valve 13, feeding water from the feed pump 10 into the secondary heat exchanger 6, heating the water in the secondary heat exchanger 6 by using the residual heat of the flue gas at the smoke outlet end of the primary heat exchanger 5, and then inputting the water into the primary heat exchanger 5 (the primary heat exchanger 5 and the secondary heat exchanger 6 are connected in series); heating in the primary heat exchanger 5 by using the flue gas waste heat at the smoke outlet end of the dust remover 4, and inputting the heated flue gas waste heat into the economizer 2 to improve the water inlet temperature of the economizer 2; (3) closing the third valve 17, the first valve 15, the fourth valve 18 and the fifth valve 19, only opening the second valve 16, the sixth valve 20, the seventh valve 21 and the eighth valve 13, respectively sending water from the feed pump 10 into the primary heat exchanger 5 and the secondary heat exchanger 6 (the primary heat exchanger 5 and the secondary heat exchanger 6 are connected in parallel), and after heating in the secondary heat exchanger 6 by using the residual heat of the flue gas at the smoke outlet end of the primary heat exchanger 5, inputting the water into the primary heat exchanger 5; the water from the water feeding pump 10 and the secondary heat exchanger 6 is heated by the waste heat of the flue gas at the smoke outlet end of the dust remover 4 in the primary heat exchanger 5 and then is input into the economizer 2, so that the inlet water temperature of the economizer 2 is increased;
when the temperature of the primary air entering the boiler is low, the temperature of the primary air can be increased by adjusting relevant valves, such as: (1) closing the third valve 17, the first valve 15, the eighth valve 13 and the seventh valve 21, opening only the second valve 16, the sixth valve 20, the fourth valve 18 and the fifth valve 19, feeding water from the feed pump 10 into the secondary heat exchanger 6, heating the water in the secondary heat exchanger 6 by using the residual heat of the flue gas at the smoke outlet of the primary heat exchanger 5, and then inputting the water into the primary heat exchanger 5 (the primary heat exchanger 5 and the secondary heat exchanger 6 are connected in series); the flue gas waste heat at the smoke outlet end of the dust remover 4 is used in the primary heat exchanger 5 for heating and then is input into the air heat exchanger 9, so that the air from the blower 12 is heated in the air heat exchanger 9, and the temperature of the air entering the air preheater 3 is increased; the air heated by the air heat exchanger 9 is input into the air preheater 3, and in the air preheater 3, the air is heated by using the waste heat of the flue gas at the smoke outlet end of the economizer 2 and then is input into the boiler as primary air, so that the temperature of the primary air entering the boiler is increased; (2) closing the third valve 17, the first valve 15 and the eighth valve 13, opening only the second valve 16, the sixth valve 20, the seventh valve 21, the fourth valve 18 and the fifth valve 19, sending water from the feed pump 10 into the primary heat exchanger 5 and the secondary heat exchanger 6 respectively (the primary heat exchanger 5 is connected in parallel with the secondary heat exchanger 6), and inputting the water into the primary heat exchanger 5 after the water is heated by the residual heat of the flue gas at the smoke outlet end of the primary heat exchanger 5 in the secondary heat exchanger 6; the water from the feed water pump 10 and the secondary heat exchanger 6 is heated by the residual heat of the flue gas at the smoke outlet end of the dust remover 4 in the primary heat exchanger 5 and then is input into the air heat exchanger 9, so that the air from the blower 12 is heated in the air heat exchanger 9, and the temperature of the air entering the air preheater 3 is increased; the air heated by the air heat exchanger 9 is input into the air preheater 3, and in the air preheater 3, the air is heated by using the waste heat of the flue gas at the smoke outlet end of the economizer 2 and then is input into the boiler as primary air, so that the temperature of the primary air entering the boiler is increased.
The waste heat cascade utilization system for the coal-fired flue gas has simple structure, can flexibly adjust the waste heat utilization mode, freely switches the serial and parallel waste heat utilization modes of the primary heat exchanger and the secondary heat exchanger, performs cascade utilization on the flue gas waste heat, fully utilizes the flue gas waste heat, and has high utilization efficiency of the flue gas waste heat; the temperature of primary air can be improved, the ignition performance of pulverized coal is enhanced, the combustion stability of a boiler is enhanced, and the adaptability of burning inferior coal is improved; the heat efficiency of the boiler can be improved, meanwhile, acid condensation and condensation in the economizer area can be inhibited, acid corrosion is slowed down, and the service life of the economizer equipment is prolonged.
Claims (10)
1. A cascade utilization system of waste heat of coal-fired flue gas comprises a boiler and a chimney (1) which are communicated with each other through a flue, and is characterized in that,
in the waste heat cascade utilization system, an economizer (2), an air preheater (3), a dust remover (4), a primary heat exchanger (5), a secondary heat exchanger (6), an induced draft fan (7) and an absorption tower (8) are sequentially arranged in the flue and used for sequentially processing the flue gas from the boiler so as to empty the flue gas from the chimney (1);
the waste heat cascade utilization system also comprises an air heat exchanger (9), a water feed pump (10), a circulating water pump (11) and a blower (12);
the water inlet end of the coal economizer (2) is connected to the feed water pump (10), the water outlet end of the coal economizer is connected to the boiler, and the coal economizer is used for heating water from the feed water pump (10) by using the waste heat of the flue gas from the boiler so as to supply the water to the boiler;
the water inlet end of the primary heat exchanger (5) is respectively connected to the water inlet end of the water feeding pump (10) and the water outlet end of the air heat exchanger (9), the water outlet end of the primary heat exchanger (5) is respectively connected to the water inlet end of the economizer (2) and the water inlet end of the air heat exchanger (9), and the primary heat exchanger is used for heating water from the water feeding pump (10) and/or the air heat exchanger (9) by using the waste heat of the flue gas from the dust remover (4) to supply the water to the economizer (2) and/or the air heat exchanger (9); the circulating water pump (11) is arranged on a pipeline from the water outlet end of the primary heat exchanger (5) to the water inlet end of the air heat exchanger (9);
the water inlet end of the air heat exchanger (9) is connected to the water outlet end of the primary heat exchanger (5) through the circulating water pump (11), the water outlet end of the air heat exchanger (9) is connected to the water inlet end of the primary heat exchanger (5), the air inlet end of the air heat exchanger (9) is connected to the blower (12), the air outlet end of the air heat exchanger (9) is connected to the air preheater (3) and used for circularly heating the air from the blower (12) by using the water from the primary heat exchanger (5) to supply to the air preheater (3);
the air inlet end of the air preheater (3) is connected to the air outlet end of the air heat exchanger (9), the air outlet end of the air preheater (3) is connected to the boiler, and the air from the air heat exchanger (9) is heated by using the residual heat of the flue gas from the economizer (2) to be supplied to the boiler as primary air;
the water inlet end of the secondary heat exchanger (6) is connected to the water feeding pump (10), the water outlet end of the secondary heat exchanger is connected to the water inlet end of the economizer (2) and used for heating water from the water feeding pump (10) by using the waste heat of the flue gas from the primary heat exchanger (5) so as to supply the water to the economizer (2);
the water outlet end of the secondary heat exchanger (6) is also connected to the water inlet end of the primary heat exchanger (5) and is used for heating water from the secondary heat exchanger (6) by using the flue gas waste heat from the dust remover (4) in the primary heat exchanger (5) to supply the economizer (2) and/or the air heat exchanger (9).
2. The waste heat cascade utilization system according to claim 1, wherein a first valve (15) is provided on a first pipeline from the feed water pump (10) to the economizer (2) for opening/closing to connect/block water feed from the feed water pump (10) to the economizer (2).
3. The waste heat cascade utilization system according to claim 2, characterized in that the water inlet end of the secondary heat exchanger (6) is provided with a second valve (16) for opening/closing to communicate/block the water inlet of the feed water pump (10) to the secondary heat exchanger (6).
4. A waste heat cascade utilization system according to claim 3, characterized in that the water outlet end of the secondary heat exchanger (6) is provided with a third valve (17) for opening/closing to communicate/block the water inlet of the secondary heat exchanger (6) to the economizer (2).
5. The waste heat cascade utilization system according to claim 4, wherein the water inlet end and the water outlet end of the secondary heat exchanger (6) are respectively connected to the first pipeline and are respectively located at the water inlet end and the water outlet end of the first valve (15); the second valve (16) is arranged on a third pipeline from the water inlet end of the first valve (15) to the water inlet end of the secondary heat exchanger (6); the third valve (17) is arranged on a fourth pipeline from the water outlet end of the secondary heat exchanger (6) to the water outlet end of the first valve (15).
6. A waste heat cascade utilization system according to claim 4 or 5, characterized in that the water inlet end of the circulating water pump (11) is provided with a fourth valve (18) for opening/closing to communicate/block the water inlet of the primary heat exchanger (5) to the air heat exchanger (9).
7. The waste heat cascade utilization system as claimed in claim 6, wherein a fifth valve (19) is arranged at a water outlet end of the air heat exchanger (9) and is used for opening/closing to communicate/block water inlet of the air heat exchanger (9) to the primary heat exchanger (5).
8. The waste heat cascade utilization system according to claim 7, wherein a sixth valve (20) is arranged on a second pipeline from the water outlet end of the secondary heat exchanger (6) to the water inlet end of the primary heat exchanger (5) and is used for opening/closing to communicate/block the water inlet of the secondary heat exchanger (6) to the primary heat exchanger (5); and two ends of the second pipeline are respectively connected to the water inlet end of the third valve (17) and the water outlet end of the fifth valve (19).
9. The waste heat cascade utilization system according to claim 8, wherein a seventh valve (21) is disposed on a fifth pipeline from the water outlet end of the second valve (16) to the water outlet end of the sixth valve (20) for opening/closing simultaneously with the second valve (16) to communicate/block the water inlet of the feed water pump (10) to the primary heat exchanger (5).
10. The waste heat cascade utilization system according to any one of claims 7-9, wherein an eighth valve (13) is arranged on a sixth pipeline from the water outlet end of the primary heat exchanger (5) to the water inlet end of the economizer (2); the water inlet end of the eighth valve (13) is connected to the water inlet end of the fourth valve (18), and the water outlet end of the eighth valve (13) is connected to the water outlet end of the first valve (15) and used for opening/closing to communicate/block the water inlet of the primary heat exchanger (5) to the economizer (2).
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| Application Number | Priority Date | Filing Date | Title |
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| CN202023225397.4U CN214370115U (en) | 2020-12-28 | 2020-12-28 | Waste heat cascade utilization system for coal-fired flue gas |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202023225397.4U CN214370115U (en) | 2020-12-28 | 2020-12-28 | Waste heat cascade utilization system for coal-fired flue gas |
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| CN214370115U true CN214370115U (en) | 2021-10-08 |
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