CN216557143U

CN216557143U - Flue gas self-circulation device for comprehensively utilizing waste heat

Info

Publication number: CN216557143U
Application number: CN202120745903.8U
Authority: CN
Inventors: 王进; 王沛丽; 朱真真; 徐刚
Original assignee: Everbright Envirotech China Ltd; Everbright Environmental Protection Research Institute Nanjing Co Ltd; Everbright Environmental Protection Technology Research Institute Shenzhen Co Ltd
Current assignee: Everbright Envirotech China Ltd; Everbright Environmental Protection Research Institute Nanjing Co Ltd; Everbright Environmental Protection Technology Research Institute Shenzhen Co Ltd
Priority date: 2021-04-13
Filing date: 2021-04-13
Publication date: 2022-05-17
Anticipated expiration: 2031-04-13

Abstract

The utility model provides a flue gas self-circulation device for comprehensively utilizing waste heat, which comprises an incinerator, a Venturi tube, a waste heat boiler and the like; the incinerator is internally provided with three sections of grates, three ash hoppers are arranged below the three sections of grates, the lower right wall of the furnace body is provided with a slag falling well, the bottom of the slag falling well is provided with a slag dragging machine, a smoke outlet of the incinerator is connected with a waste heat boiler, a primary air preheater is respectively connected with the three ash hoppers through pipelines, a primary fan is respectively arranged on the pipelines, a Venturi tube is arranged on a pipeline between the primary air preheater and a primary fan of a drying section, a backflow pipeline is respectively communicated with the Venturi tube, the waste heat boiler and the slag falling well through pipelines, and an ash conveying machine is communicated with the waste heat boiler and the slag falling well. The utility model has simple system, low investment, strong primary air heating capacity, capability of reducing the excess air coefficient of incineration, reducing the heat loss of exhaust smoke and reducing the generation of NOx in the furnace, and has the effect of achieving multiple purposes.

Description

Flue gas self-circulation device for comprehensively utilizing waste heat

Technical Field

The utility model belongs to the field of incinerator equipment, and relates to a flue gas self-circulation device for comprehensively utilizing waste heat.

Background

Due to the characteristics of high moisture, high ash content and low calorific value, in order to ensure thorough incineration of the household garbage, the primary air temperature needs to be increased during incineration, the calorific value of the garbage is low, the primary air temperature is higher, the primary air temperature of a general grate furnace is 200-220 ℃, and the primary air temperature needed in winter in cold northern areas is higher.

The existing mainstream primary air heating method is that primary air is heated and heated in an air preheater by using steam extraction of a steam drum of a waste heat boiler and one extraction of a steam turbine, and the condition of energy waste is serious when the primary air is heated due to high steam quality, so that the capacity of the air preheater and the steam extraction quantity must be continuously enlarged if the primary air temperature needs to be increased; in addition, the requirement on the primary air temperature of the incinerator is higher in cold areas in winter in the north, the existing primary air heating technology is difficult to further improve the primary air temperature, and if the primary air temperature is further improved, the energy waste is more serious; the primary air of the drying section is mainly used for drying fresh garbage entering the incinerator, only a few parts of the garbage on the surface layer can start to catch fire, and high-concentration oxygen in the air cannot be fully utilized, so that the excess air coefficient of the incinerator is high, the heat loss of exhaust smoke is improved, and the generation of NOx is increased.

At present, the number of patents similar to the utility model is few, most of flue gas recycling uses the circulating flue gas as secondary air to be sprayed from the upper part of the incinerator (CN 208382176U, CN 110822446A), and the similar patent is that a high-temperature fan is used for extracting the circulating flue gas from a draught fan and returning the circulating flue gas to a primary air ash bucket for temperature raising (CN 110486728A), but because the circulating flue gas temperature is lower (130-140 ℃), and a high-temperature fan is needed, the heating effect is not obvious, and the cost is higher; in some patents, the flue gas in the middle of the exhaust-heat boiler is extracted and returned to the boiler to be used as secondary air (CN 209706057U). The utility model is obviously different from the schemes.

SUMMERY OF THE UTILITY MODEL

The technical problem to be solved is as follows: aiming at the technical problems, the utility model provides a flue gas self-circulation device for comprehensively utilizing waste heat, which adopts a self-circulation method to return a small amount of high-temperature flue gas in a waste heat boiler to the front of the boiler, and directly mixes the flue gas with primary air of a drying section to raise the temperature, so that the use amount of partial primary air can be replaced, the load of an air preheater can be reduced, and the excess air coefficient in the boiler can be further reduced, thereby solving the heating problem of the primary air of the drying section in the household garbage incineration process, economically and efficiently improving the temperature of the primary air of the drying section, and bringing benefits including reducing the excess air coefficient in the boiler, reducing the heat loss of smoke exhaust and reducing the generation of nitrogen oxides (NOx) in the boiler.

The technical scheme is as follows: a flue gas self-circulation device for comprehensively utilizing waste heat comprises an incinerator, a primary air preheater, a waste heat boiler, a spiral ash conveyor, a Venturi tube and a return pipeline, wherein three sections of fire grates are arranged in the incinerator, sequentially comprise a drying section, a combustion section and a burnout section from left to right, a drying section ash hopper, a combustion section ash hopper and a burnout section ash hopper which are sequentially arranged from left to right are arranged below the three sections of fire grates, a slag falling well is arranged on the lower right wall of a furnace body, and the slag falling well is positioned on the right side of the three sections of fire grates; the bottom that falls the sediment well is equipped with the dragveyer, burn the mouth that the burning furnace goes out the cigarette and be connected with exhaust-heat boiler, an air preheater is connected with dry section ash bucket, combustion section ash bucket and burn the ashes section ash bucket respectively through three pipelines, and is equipped with dry section primary air fan, combustion section primary air fan and burns the ashes section primary air fan on three pipelines respectively, spiral ash conveyor upper end and exhaust-heat boiler intercommunication, the lower extreme is through dredging the ash pipe and falling the sediment well intercommunication, venturi locates on the pipeline between an air preheater and the dry section primary air fan, the backflow pipeline is the V-arrangement pipe, the one end of V-arrangement pipe is passed through pipeline and venturi's narrowest throat department intercommunication, and the other end passes through flue gas backflow pipeline and exhaust-heat boiler intercommunication, the lower department in the middle of the V-arrangement pipe is passed through backflow pipeline dredging the ash pipe and is communicate with the sediment well that falls.

Further, a feed inlet is formed in the left side wall of the furnace body.

Furthermore, the other end of the V-shaped pipe is communicated with the waste heat boiler through a flue gas backflow pipeline, and the flue gas backflow pipeline extends into the lower portion of the second flue of the waste heat boiler.

Furthermore, the inward folding angle of the V-shaped flue is less than or equal to 100 degrees.

Furthermore, the upper end of the spiral ash conveyor is communicated with the lower end of a second flue or the lower end of a third flue of the waste heat boiler.

Furthermore, a secondary air inlet is arranged on the side wall of the throat of the incinerator.

Has the advantages that:

1. the system is simple and the investment is low. The utility model can perform auxiliary upgrade on the existing mainstream primary air heating system, only needs to add part of pipelines, Venturi tubes, ash removal systems, valves, instruments and the like, does not need to add a single high-temperature resistant fan, and has simple system and investment saving;

2. the self-backflow smoke extraction port is positioned in the middle of the waste heat boiler, the temperature of backflow smoke is high (650-700 ℃), the heating capacity of primary air is high, and the amount of backflow smoke can be dynamically adjusted by using the opening of a valve as required;

3. the flue gas backflow heating primary air can save high-quality steam drum extraction steam and steam turbine one-extraction consumption in the air preheater, lower-quality flue gas sensible heat is used instead, and the heat economy of the system is improved;

4. the backflow flue gas can replace part of fresh air, reduce the excess air burning coefficient, reduce the heat loss of exhaust smoke, and simultaneously reduce the generation of NOx in the furnace, thereby having the effect of multiple purposes.

Drawings

FIG. 1 is a schematic view of the air distribution and combustion process in an incinerator.

In the figure, 1-primary air preheater; 2-a venturi tube; 3-primary fan of drying section; 4-drying section ash bucket; 5-a drying section; 6-a combustion section; 7-burnout section; 8-a slag falling well; 9-a slag conveyor; 10-an incinerator; 11-secondary air inlet; 12-a waste heat boiler; 13-a spiral ash conveyer; 14-a soot blower; 15-flue gas return line; 16-a return duct soot blower; 17-a first flue; 18-a second flue; 19-third flue.

Detailed Description

The utility model is further explained below with reference to the drawings.

Example 1

As shown in fig. 1, a flue gas self-circulation device for comprehensively utilizing waste heat comprises an incinerator 10, a primary air preheater 1, a venturi tube 2, a waste heat boiler 12 and a spiral ash conveyor 13; the incinerator comprises an incinerator body, a high-temperature flue gas outlet is formed in the upper portion of the incinerator body, a feed inlet is formed in the left side wall of the incinerator body, a secondary air inlet 11 is formed in the side top wall of the incinerator body, three sections of grates are arranged below the high-temperature flue gas outlet, the three sections of grates sequentially comprise a drying section 5, a combustion section 6 and a burn-out section 7 from left to right, a drying section ash hopper 4, a combustion section ash hopper and a burn-out section ash hopper which are sequentially arranged from left to right are arranged below the three sections of grates, a slag falling well 8 is arranged on the lower right wall of the incinerator body, and the slag falling well 8 is located on the right side of the three sections of grates; a slag dragging machine 9 is arranged at the bottom of the slag falling well, the high-temperature flue gas outlet is connected with a waste heat boiler 12, the primary air pre-heater 1 is respectively connected with a drying section ash bucket 4, a combustion section ash bucket and a burning section ash bucket through pipelines, a drying section primary fan 3 is arranged on the pipeline between the primary air pre-heater and the drying section ash bucket, a combustion section primary fan is arranged on the pipeline between the primary air pre-heater and the burning section ash bucket, a burning section primary fan is arranged on the pipeline between the primary air pre-heater and the burning section ash bucket, the upper end of the spiral ash conveyer 13 is connected with the lower end of a second flue or the lower end of a third flue of the waste heat boiler 12, the lower end of the spiral ash conveyer is communicated with the slag falling well through an ash dredging pipe 14, and a first flue 17 in the waste heat boiler guides waste gas generated by combustion in the combustion chamber upwards; the second flue 18 guides the exhaust gas from the first flue downward, and the third flue 19 guides the exhaust gas from the second flue downward upward. .

On locating the pipeline between air preheater and the dry section primary air fan with venturi 2, venturi's effect has two, one is making the low pressure in one step before the primary air fan, increases flue gas backflow pipeline's pressure differential, improves flue gas reflux capacity, and two is increasing the mixing of backward flow flue gas and primary air, shortens the length of mixing required pipeline. The return duct is a V-shaped duct, the angle of the inner bend of the V-shaped flue is preferably less than or equal to 100 degrees, one end of the V-shaped duct is communicated with the narrowest throat of the Venturi tube through a duct, the other end of the V-shaped duct is communicated with the waste heat boiler 12 through a flue gas return duct 15, the flue gas return duct is positioned in front of the evaporation screen heat exchanger at the leading-out point of the waste heat boiler and is higher than the ash port at the lower part of the flue, so the flue gas return duct extends into a second flue in the middle of the waste heat boiler, the extending end of the return duct is positioned at the lower part of the second flue, the flue gas return duct is also provided with a valve, the lowest part in the middle of the V-shaped duct is communicated with the slag well through a return duct ash removing pipe 16, the design of the return duct and the ash removing pipe are also important, the return duct is designed into a V-shaped structure to facilitate the deposition of fly ash at the lower point, and the ash removing duct is connected with the slag well of the incinerator, the deposited fly ash is sent into the slag falling well by intermittently opening the pipeline valve, so that the problem of high content of the fly ash in the flue gas of the waste heat boiler is effectively solved.

Because the front of the primary air fan and the back of the air preheater are low-pressure areas of a primary air system, the negative pressure range is-300 to-1000 Pa, the negative pressure in the middle of the waste heat boiler is-50 to-150 Pa, a return pipeline is connected to the front pipeline of the primary air fan and the middle of the waste heat boiler through a pipeline, and the return pipeline can pump smoke (650-700 ℃) in the waste heat boiler to primary air under the action of pressure difference; in addition, the joint of the return pipeline and the primary air pipe is designed into a venturi tube, and the design has the functions of enhancing the flue gas backflow capacity and promoting mixing, so that the effect of the utility model is greatly improved. By combining the design and the higher temperature of the backflow flue gas, the temperature of the primary air is rapidly increased to 250-350 ℃ after the primary air is mixed with the primary air in the drying section, and the heating temperature can be freely controlled according to the opening degree of a valve of a backflow pipeline. The design scheme of utilizing the self-pressure difference in the incinerator system to automatically return the flue gas to the primary air of the drying section. The scheme is original. Meanwhile, the backflow flue gas comes from the high-temperature flue gas in the middle of the waste heat boiler, has a very strong primary air heating function, is particularly suitable for low-calorific-value garbage in the north and household garbage incineration plants difficult to incinerate in winter, and is a great characteristic of the utility model. The utility model adopts a self-circulation mode to utilize high-temperature flue gas in the waste heat boiler to supply primary air for temperature raising, the system is simple, and the investment saving and temperature raising effects are obvious; the system can also be used as an auxiliary upgrading technology of the existing mainstream primary air heating method, only the existing system is required to be transformed and upgraded, part of pipelines, Venturi tubes and ash removing systems are added, and valves, instruments and the like which are used in a matched mode are added, a single high-temperature resistant fan is not required to be added, the system is slightly modified, and the economical efficiency is high.

Claims

1. The utility model provides a flue gas self-loopa device of waste heat comprehensive utilization which characterized in that: the energy-saving boiler comprises an incinerator, a primary air preheater, a waste heat boiler, a spiral ash conveyor, a Venturi tube and a return pipeline, wherein three sections of grates are arranged in the incinerator, the three sections of grates are a drying section, a combustion section and an ash burning section from left to right in sequence, an ash hopper of the drying section, an ash hopper of the combustion section and an ash burning section which are sequentially arranged from left to right are arranged below the three sections of grates, a slag falling well is arranged on the lower right wall of a furnace body, and the slag falling well is positioned on the right side of the three sections of grates; the bottom that falls the sediment well is equipped with the dragveyer, burn the mouth that the burning furnace goes out the cigarette and be connected with exhaust-heat boiler, an air preheater is connected with dry section ash bucket, combustion section ash bucket and burn the ashes section ash bucket respectively through three pipelines, and is equipped with dry section primary air fan, combustion section primary air fan and burns the ashes section primary air fan on three pipelines respectively, spiral ash conveyor upper end and exhaust-heat boiler intercommunication, the lower extreme is through dredging the ash pipe and falling the sediment well intercommunication, venturi locates on the pipeline between an air preheater and the dry section primary air fan, the backflow pipeline is the V-arrangement pipe, the one end of V-arrangement pipe is passed through pipeline and venturi's narrowest throat department intercommunication, and the other end passes through flue gas backflow pipeline and exhaust-heat boiler intercommunication, the lower department in the middle of the V-arrangement pipe is passed through backflow pipeline dredging the ash pipe and is communicate with the sediment well that falls.

2. The flue gas self-circulation device for comprehensively utilizing waste heat according to claim 1, characterized in that: and a feed inlet is formed in the left side wall of the furnace body.

3. The flue gas self-circulation device for comprehensively utilizing waste heat according to claim 1, characterized in that: the other end of the V-shaped pipe is communicated with the waste heat boiler through a flue gas backflow pipeline, and the flue gas backflow pipeline extends into the lower portion of the second flue of the waste heat boiler.

4. The flue gas self-circulation device for comprehensively utilizing waste heat according to claim 1, characterized in that: the inward folding angle of the V-shaped pipe is less than or equal to 100 degrees.

5. The flue gas self-circulation device for comprehensively utilizing waste heat according to claim 1, characterized in that: and the upper end of the spiral ash conveyor is communicated with the lower end of a second flue or the lower end of a third flue of the waste heat boiler.

6. The flue gas self-circulation device for comprehensively utilizing waste heat according to claim 1, characterized in that: and a secondary air inlet is formed in the side wall of the throat of the incinerator.