Energy-saving method for automatic adjustment and use of flue gas waste heat recovery of garbage power plant

Abstract

The invention relates to an energy-saving method for flue gas waste heat recovery and automatic adjustment and use of a garbage power plant, which solves the technical problems of low garbage incineration efficiency and serious heat waste of the existing garbage incineration power plant, and comprises the following specific steps: step 1, mounting a flue gas heat exchanger at the middle section from an outlet of an induced draft fan to a chimney for gas-water heat exchange; heat medium water is generated through gas-water heat exchange of the flue gas heat exchanger; 2, the heating medium water is directly connected with an air heating system to circularly convey a heat source, and the air heating system conducts air-water heat exchange with sucked air through the heating medium water; and 3, the exchanged hot air is provided as a heat source in front of a primary air fan according to actual needs, the primary air temperature is increased, or the exchanged hot air is converted to an air circulation fan, and the hot air is provided for the low-temperature garbage bin, the garbage temperature is increased, and garbage fermentation is facilitated through a pipeline arranged inside or outside the garbage bin. The device can be widely applied to waste incineration occasions of waste incineration power plants.

Description

Technical Field

[0001] The invention relates to the field of garbage disposal, and in particular to an energy-saving method for automatically regulating and recovering waste heat from flue gas in a garbage power plant. Background Art

[0002] After domestic garbage enters the waste incineration power plant, the garbage first needs to be continuously stacked by the garbage crane, fermented at a certain temperature for 5-7 days, and the leachate is removed to increase the calorific value before it can be incinerated. Due to the low temperature in autumn and winter, the stacking fermentation efficiency is low, and the garbage cannot be effectively fermented, resulting in low calorific value of the garbage. Auxiliary fuel needs to be added to ensure the normal operation of the waste incineration boiler. On the other hand, due to the particularity of waste incineration, the exhaust flue gas temperature is high after the garbage is incinerated. If the flue gas temperature is forcibly lowered, the flue gas reaches the acid dew point, which is easy to cause corrosion; at the same time, due to the dry / semi-dry desulfurization process used in the waste incineration process, the desulfurization is not thorough, which is also easy to cause corrosion. The latest environmental protection requirements for the incinerator exhaust flue gas temperature to be controlled within 45°C, so how to reasonably utilize the waste incineration boiler flue gas waste heat and solve the effective fermentation of garbage in autumn and winter has become an urgent problem to be solved. Summary of the invention

[0003] In order to solve the technical problems of low waste incineration efficiency and heat waste in existing waste incineration power plants, the present invention provides an energy-saving method for automatically adjusting the use of flue gas waste heat recovery in waste power plants to improve the fermentation efficiency of waste stacking.

[0004] The present invention provides an energy-saving method for automatically adjusting and using waste heat recovery from flue gas in a garbage power plant, and the specific steps include:

[0005] Step 1: Install a flue gas heat exchanger between the outlet of the induced draft fan and the middle section of the chimney to perform air-water heat exchange, and generate heat medium water through the flue gas heat exchanger for air-water heat exchange;

[0006] Step 2: The heat medium water is directly connected to the air heating system to circulate and transport the heat source. The air heating system uses the heat medium water and the sucked air to perform air-water heat exchange;

[0007] Step 3, the exchanged hot air is provided to the primary fan as a heat source according to actual needs to increase the primary air temperature, or is converted to the air circulation fan and used to provide hot air to the low-temperature garbage bin through pipelines installed inside or outside the garbage bin to increase the garbage temperature and facilitate garbage fermentation.

[0008] Preferably, step 4 is further provided, in which the hot air delivered to the garbage bin is forcibly replaced with the cold air on the garbage surface and in the bin, and the replaced air is provided to the boiler primary fan for use as fresh air.

[0009] Preferably, the specific method of replacing the cold air with the hot air sprayed by the jet rotating nozzle in the garbage bin in step 4 is:

[0010] Step 1), adjusting the direction of the jet rotating nozzle of the air replacement device according to the position of the garbage in the garbage bin; starting the push-pull motor, and the push-pull motor drives the arched push-pull rod to adjust the spraying direction of each group of jet rotating nozzles;

[0011] Step 2), start the jet rotary nozzle, and let the waste heat from the boiler smoke chamber enter the jet rotary nozzle through the air duct. After the jet rotary nozzle is aimed at the garbage, it sprays hot air to the garbage bin. The hot air stirs the cold air in the garbage bin, forces convection heat exchange, and the hot air mixes with the cold air in the garbage bin, thereby increasing the temperature of the garbage bin and taking away the moisture on the surface of the garbage, accelerating the heating and fermentation of the garbage;

[0012] Step 3), when the garbage crane transfers the garbage in the bin, the position of the accumulated garbage changes, and the position of the jet rotating nozzle is automatically adjusted, and the jet rotating nozzle is aimed at the garbage again to spray, and steps 1) to 3) are repeated.

[0013] Preferably, in step 1, the flue gas heat exchanger is provided with a regulating switching valve controlled by a PLC, which is used to open and close the flue gas heat exchanger or adjust the flue gas flow of the flue gas heat exchanger; when the flue gas heat exchanger needs to be closed, the regulating switching valve connected in series with the flue gas heat exchanger is closed, and the regulating switching valve connected in parallel with the flue gas heat exchanger is opened; when the flue gas heat exchanger needs to be started, the regulating switching valve connected in series with the flue gas heat exchanger is opened, and the regulating switching valve connected in parallel with the flue gas heat exchanger is closed; when the heat output of the flue gas heat exchanger needs to be adjusted, the regulating switching valve connected in series with the flue gas heat exchanger is opened, and at the same time, the regulating switching valve connected in parallel with the flue gas heat exchanger is opened and the opening of the regulating switching valve is adjusted.

[0014] Preferably, in step 2, the air heating system is provided with a regulating switching valve controlled by a PLC, and by opening or closing the regulating switching valve of the front and rear connecting pipes of the air heating system, the air heating system heats the primary air or heats the garbage bin, or adjusts the heating amount of the air heating system.

[0015] Preferably, the heat medium water in step 2 can also heat the heat exchange unit to increase the temperature of the deoxygenated water.

[0016] Preferably, in step 1, after the flue gas heat exchange, there is also a cooling and gas washing process, by spraying alkaline water to clean the solid particles and acidic substances in the flue gas, thereby reducing the pH value of the flue gas to meet the emission standards.

[0017] Beneficial effects of the present invention:

[0018] The present invention is provided with an air heating system at the front end of the boiler, and a flue gas heat exchanger is installed in the middle section from the outlet of the boiler induced draft fan to the chimney. The flue gas filtered by the garbage incineration is subjected to air-water heat exchange by the flue gas heat exchanger to generate heat medium water which is directly connected to the air heating system for cyclic transmission of heat source. The air heating system uses heat medium water and the air sucked by the primary fan for air-water heat exchange, which can effectively increase the temperature of the primary air and reduce the heat loss of heating the primary air. The source of the primary fan is the air in the garbage bin, and negative pressure is formed in the garbage bin by sucking the air from the garbage bin to prevent the spread of garbage odor.

[0019] The flue gas heat exchanger also uses a switchable pipe network to heat the garbage in the garbage bin. When the weather changes and the temperature of the garbage in the garbage bin is too low, the humidity of the garbage is high, and the calorific value is low, which affects the heating of the boiler, the air heating system uses heat medium water to heat the air and provide high-temperature hot air to the garbage bin. The high-temperature hot air enters the ejector through the air duct, and performs forced convection heat exchange on the cold air in the garbage bin and the garbage surface, thereby increasing the temperature of the garbage, accelerating the drying and fermentation of the garbage, and increasing the calorific value of the garbage. This reduces the need to add auxiliary fuel due to the inability to effectively ferment the garbage in winter, reduces energy losses, and avoids energy waste.

[0020] The present invention further provides a cooling scrubber between the flue gas heat exchanger and the chimney. Since waste incineration requires dry or semi-dry dust removal, it is impossible to completely remove the acidic substances in the flue gas. By spraying alkaline water on the cooling scrubber, the acidic substances in the flue gas can be removed again by utilizing the acid-base neutralization reaction, thereby achieving the required pH emission standard, protecting the flue and preventing the flue from corrosion. At the same time, by spraying water for washing, the flue gas temperature can be reduced to below 45°C, while ensuring that the 24-hour average emission concentration of particulate matter is not higher than 5mg / m 3 The 24-hour average emission concentration of nitrogen oxides is not higher than 80 mg / m 3 The 24-hour average emission concentration of hydrogen chloride is not higher than 8 mg / m 3 . BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the energy-saving system of the present invention in an incinerator;

[0022] Figure 2 It is a schematic diagram of the process of the present invention;

[0023] Figure 3 It is a schematic diagram of the front view structure of the air replacement device of the present invention;

[0024] Figure 4 It is a structural schematic diagram of a left view of the air replacement device of the present invention;

[0025] Figure 5 It is a schematic diagram of the position of the air replacement device of the present invention in the garbage bin.

[0026] Description of the accompanying symbols:

[0027] 1. Air duct; 2. Guardrail; 3. Rack; 4. Push-pull motor; 5. Slide bracket; 6. Jet rotating nozzle; 7. Arch push-pull rod; 10. Garbage pool; 20. Incinerator; 21. Feed hopper; 22. Chute; 30. Desulfurization tower; 40. Bag filter; 50. Chimney; 600. Cooling and washing tower; 601. Flue gas heat exchanger; 602. Draft fan; 603. First regulating switching valve; 604. Second regulating switching valve; 605. Third regulating switching valve; 606. Circulating water pump; 607. Air heating system; 608. Fourth regulating switching valve; 609. Fifth regulating switching valve; 610. Air circulation fan; 611. Sixth regulating switching valve; 612. Seventh regulating switching valve; 71. Air inlet; 72. Air waste heat system; 73. Primary fan. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings and embodiments so that those skilled in the art can easily implement the present invention.

[0029] Example: Figure 1 The figure shows a schematic diagram of the structure of the energy-saving system of the present invention in an incinerator / waste heat boiler. The present invention is based on the existing incinerator / waste heat boiler, which is provided with a garbage pool 10, an incinerator 20, a desulfurization tower 30, a bag filter 40 and a chimney 50 in sequence. The garbage pool 10 provides heat generated by garbage incineration to the incinerator 20 or the waste heat boiler through a feeding hopper 21 and a chute 22. After combustion, the high-temperature flue gas passes through the desulfurization tower 30 and the bag filter 40 and then enters the chimney. The air in the garbage pool 10 enters the air waste heat system 72 from the pipeline through the air intake 71 for heating. After the temperature is raised to about 200 degrees Celsius, it passes through a primary fan 73 and enters the incinerator 20 for combustion.

[0030] The present invention is provided with an induced draft fan 602 and a flue gas heat exchanger 601 between the bag filter 40 and the chimney 50, and three regulating switching valves are used to control the opening and closing of the flue gas heat exchanger 601 and the adjustment of the flue gas volume, so as to realize waste heat recovery. The induced draft fan 602 introduces the hot gas discharged from the bag filter 40 into the flue gas heat exchanger 601 to heat the water in the flue gas heat exchanger 601. The first regulating switching valve 603 and the second regulating switching valve 604 are connected in series at both ends of the flue gas heat exchanger 601, and the third regulating switching valve 605 is connected in parallel with the first regulating switching valve 603, the second regulating switching valve 604 and the flue gas heat exchanger 601. When the flue gas heat exchanger 601 needs to be disabled, the first regulating switching valve 603 and the second regulating switching valve 604 are closed, and the third regulating switching valve 605 is opened; conversely, when the flue gas heat exchanger 601 needs to be enabled, the first regulating switching valve 603 and the second regulating switching valve 604 are opened, and the third regulating switching valve 605 is closed; when the flue gas volume needs to be adjusted, the first regulating switching valve 603, the second regulating switching valve 604 and the third regulating switching valve 605 are all opened, and the opening degree of the third regulating switching valve 605 is adjusted to control the amount of flue gas that needs to be discharged.

[0031] The water heated by the flue gas heat exchanger 601 enters the air heating system 607 through the circulating water pump 606, providing a heat source for the air heating system 607. The air heating system 607 can heat the garbage bin 10 or the primary air entering the incinerator 20 according to actual needs, thereby improving the overall boiler efficiency and saving energy consumption. The air heating system 607 is connected to the air intake 71, the air circulation fan 610, and the air waste heat system 72 through multiple regulating switching valves, wherein one end of the air heating system 607 is connected to the sixth regulating switching valve 611, which is used to open or close the air entering the air heating system 607, and the other end is respectively connected to the fourth regulating switching valve 608 and the fifth regulating switching valve 609. The fourth regulating switching valve 608 is connected to the air duct 1 through the air circulation fan 610 to provide heat to the garbage bin 10; the fifth regulating switching valve 609 is connected to the air waste heat system 72 to heat the primary air of the boiler; the seventh regulating switching valve 612 is connected in parallel with the air heating system 607, and can be used to close the air heating system 607 for maintenance.

[0032] After the flue gas passes through the flue gas heat exchanger 601, the flue gas temperature drops significantly and easily reaches the acid dew point. In order to avoid acid corrosion of the chimney and meet the latest environmental protection requirements that the flue gas temperature is lower than 45 degrees Celsius, a cooling scrubber 600 is also provided between the second regulating switching valve 604 of the flue gas heat exchanger 601. The cooling scrubber 600 is used to wash and cool the flue gas after the flue gas heat exchanger 601 cools down, wash out solid particles and acidic substances such as sulfur dioxide and nitrogen oxides in the flue gas, and reduce pollutants in the flue gas through acid-base neutralization reaction, and reduce the flue gas temperature to ensure that it meets the latest environmental protection requirements. The flue gas enters the cooling scrubber 600, and after multiple spray cooling, absorbs solid particles and water after acid-base neutralization reaction, and is reused after heat dissipation, filtration and other operations, and re-enters the nozzle for water washing again. After the flue gas temperature after water washing is lower than 45 degrees Celsius, it is discharged into the chimney 50.

[0033] When the temperature is low in autumn and winter, and the temperature of the garbage bin 10 is low and heat needs to be provided to the garbage bin 10, the flue gas heat exchanger 601 is activated, the first regulating switching valve 603 and the second regulating switching valve 604 are opened, and the third regulating switching valve 605 is closed. The flue gas heat exchanger 601 absorbs the waste heat in the high-temperature flue gas, and the heated water enters the air heating system 607 through the circulating water pump 606. The fifth regulating switching valve 609 and the seventh regulating switching valve 612 are closed, and the fourth regulating switching valve 608 and the sixth regulating switching valve 611 are opened. The air circulation fan 610 inhales air from the air intake 71, passes through the sixth regulating switching valve 611 and enters the air heating system 607 for heating, and enters the air replacement device of the garbage bin 10 through the fourth regulating switching valve 608. The jet rotating nozzle 6 is used to spray hot air into the garbage bin. The hot air stirs the cold air in the garbage bin, forces convection heat exchange, and mixes with the cold air in the garbage bin to increase the temperature of the garbage bin and take away moisture on the surface of the garbage, thereby accelerating the drying of the garbage.

[0034] In spring and summer when the temperature rises and when there is no need to heat the garbage bin, the air circulation fan 610, the fourth regulating switching valve 608 and the seventh regulating switching valve 612 are turned off, the sixth regulating switching valve 611 and the fifth regulating switching valve 609 are opened, and the primary fan 73 draws air from the air intake port 71. After the air is heated to about 80 degrees Celsius by the sixth regulating switching valve 611 and the air heating system 607, it enters the air waste heat system 72 from the fifth regulating switching valve 609 and continues to be heated. After reaching about 200 degrees Celsius, it enters the primary fan 73 and is provided to the boiler for combustion.

[0035] The present invention recycles the waste heat in the chimney 50 according to the season or actual needs, and provides it to the garbage bin 10 for heating or assists the air waste heat system 72 in heating air, thereby reducing the heat demand of the air waste heat system 72. The PLC is used to control various regulating switching valves and circulating water pumps and other equipment to quickly adjust the running directions of air, water flow and smoke, thereby realizing automatic control.

[0036] The flue gas heat exchanger 601 that provides heat can also provide heat to other occasions that require heating. For example, the hot water output by the flue gas heat exchanger 601 can be used to heat the heat exchange unit to increase the temperature of the deoxygenated water. Similarly, the air circulation fan 610 can also collect heat from other structures according to actual needs to heat the air.

[0037] like Figure 2 FIG. 1 is a flow chart of the energy-saving method of the present invention, and the specific steps of the present invention include:

[0038] Step 1: Install a flue gas heat exchanger between the exhaust fan outlet and the chimney to exchange air with water, and generate heat medium water through the flue gas heat exchanger. After the flue gas heat exchange, it needs to be cooled and washed. By spraying alkaline water to clean the solid particles and acidic substances in the flue gas, the pH value of the flue gas can be reduced to meet the emission standards.

[0039] Step 2: The heat medium water is directly connected to the air heating system to circulate and transport the heat source. The air heating system uses the heat medium water and the sucked air to perform air-water heat exchange.

[0040] Step 3: The hot air after exchange is provided to the primary fan as a heat source to increase the primary air temperature according to actual needs, or according to weather changes, the garbage in the garbage bin is too low to freeze, the humidity is high, and the thermal mass is low, which affects the heating of the boiler. The hot air after exchange can also be adjusted to be transferred to the air circulation fan and provided to the garbage bin as high-temperature hot air replacement to increase the temperature of the garbage and space in the bin.

[0041] Step 4, the hot air sprayed by the jet rotating nozzle installed in the garbage bin is connected and transported through the air duct to replace the cold air on the garbage surface and in the bin. The replaced air is provided to various fans for use as fresh air.

[0042] The specific method of replacing cold air with hot air ejected by the jet rotating nozzle in the garbage bin is:

[0043] Step 1), adjusting the direction of the jet rotating nozzle of the air replacement device according to the position of the garbage in the garbage bin; starting the push-pull motor, and the push-pull motor drives the arched push-pull rod to adjust the spraying direction of each group of jet rotating nozzles;

[0044] Step 2), start the jet rotary nozzle, and let the waste heat from the boiler smoke chamber enter the jet rotary nozzle through the air duct. After the jet rotary nozzle is aimed at the garbage, it sprays hot air to the garbage bin. The hot air stirs the cold air in the garbage bin, forces convection heat exchange, and the hot air mixes with the cold air in the garbage bin, thereby increasing the temperature of the garbage bin and taking away the moisture on the surface of the garbage, accelerating the drying of the garbage;

[0045] Step 3), when the garbage crane transfers the garbage in the bin, the position of the accumulated garbage changes, the position of the jet rotating nozzle is adjusted, the jet rotating nozzle is aimed at the garbage again and sprayed, and steps 1) to 3) are repeated.

[0046] like Figure 3-5 , is a schematic diagram of the structure of the garbage bin air replacement device of the present invention. A plurality of jet replacement devices are evenly distributed on the air duct 1 connected to the hot air of the boiler smoke chamber waste heat exchanger. Each jet replacement device is provided with a frame 3 and a jet rotating nozzle 6. The frame 3 is fixed on the air duct 1. The jet rotating nozzle 6 is fixed on the air duct 1 and is internally connected to the air duct 1. A push-pull motor 4 is fixed on the frame 3. The push-pull motor 4 is hinged with an arched push-pull rod 7. The arched push-pull rod 7 is connected with the spherical jet rotating nozzle 6. When the push-pull motor 4 is running, the direction of the jet rotating nozzle 6 is driven to change. The air duct 1 is also provided with a slide bracket 5 for guiding the arched push-pull rod 7. One end of the slide bracket 5 is fixed on the air duct 1, and the other end is provided with a ring. The arched push-pull rod 7 is sleeved in the ring to guide the sliding direction of the arched push-pull rod 7.

[0047] The air duct 1 is arranged inside or outside the garbage bin as required. If it is arranged outside the garbage bin, it is connected to the jet rotating nozzle 6 through the branch pipe on the air duct 1. The direction of the jet rotating nozzle 6 is directly controlled by the motor to force heat exchange in the garbage bin to heat up and ferment the garbage. A guardrail 2 for maintenance is also provided on the upper part of the air duct 1.

[0048] The above description is only for the preferred embodiments of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the scope of the claims of the present invention shall be within the scope of protection of the present invention.

Claims

1. An energy-saving method for automatically adjusting and using waste heat recovery from flue gas in a garbage power plant, characterized in that: The specific steps include: Step 1: Install a flue gas heat exchanger between the outlet of the induced draft fan and the middle section of the chimney to perform air-water heat exchange, and generate heat medium water through the flue gas heat exchanger for air-water heat exchange; Step 2: The heat medium water is directly connected to the air heating system to circulate and transport the heat source. The air heating system uses the heat medium water and the sucked air to perform air-water heat exchange; Step 3, the exchanged hot air is provided to the primary fan as a heat source according to actual needs to increase the primary air temperature, or is converted to the air circulation fan and used to provide hot air to the low-temperature garbage bin through pipelines installed inside or outside the garbage bin to increase the garbage temperature and facilitate garbage fermentation.

2. The energy-saving method for automatically adjusting and recovering waste heat from flue gas in a garbage power plant according to claim 1 is characterized in that: There is also a step 4, in which the hot air delivered to the garbage bin is forcibly replaced with the cold air on the garbage surface and in the bin, and the replaced air is provided to the boiler primary fan for use as fresh air.

3. The energy-saving method for automatically adjusting and recovering waste heat from flue gas in a garbage power plant according to claim 2 is characterized in that: The specific method of replacing the cold air with the hot air sprayed by the jet rotating nozzle in the garbage bin in step 4 is: Step 1), adjusting the direction of the jet rotating nozzle of the air replacement device according to the position of the garbage in the garbage bin; starting the push-pull motor, and the push-pull motor drives the arched push-pull rod to adjust the spraying direction of each group of jet rotating nozzles; Step 2), start the jet rotary nozzle, and let the waste heat from the boiler smoke chamber enter the jet rotary nozzle through the air duct. After the jet rotary nozzle is aimed at the garbage, it sprays hot air to the garbage bin. The hot air stirs the cold air in the garbage bin, forces convection heat exchange, and the hot air mixes with the cold air in the garbage bin, thereby increasing the temperature of the garbage bin and taking away the moisture on the surface of the garbage, accelerating the heating and fermentation of the garbage; Step 3), when the garbage crane transfers the garbage in the bin, the position of the accumulated garbage changes, and the position of the jet rotating nozzle is automatically adjusted, and the jet rotating nozzle is aimed at the garbage again to spray, and steps 1) to 3) are repeated.

4. The energy-saving method for automatically adjusting and recovering waste heat from flue gas in a garbage power plant according to claim 1 is characterized in that: In the step 1, the flue gas heat exchanger is provided with a regulating switching valve controlled by a PLC, which is used to open and close the flue gas heat exchanger or adjust the flue gas flow of the flue gas heat exchanger; when the flue gas heat exchanger needs to be closed, the regulating switching valve connected in series with the flue gas heat exchanger is closed, and the regulating switching valve connected in parallel with the flue gas heat exchanger is opened; When the flue gas heat exchanger needs to be started, the regulating switching valve connected in series with the flue gas heat exchanger is opened, and the regulating switching valve connected in parallel with the flue gas heat exchanger is closed; when the heat output of the flue gas heat exchanger needs to be adjusted, the regulating switching valve connected in series with the flue gas heat exchanger is opened, and at the same time, the regulating switching valve connected in parallel with the flue gas heat exchanger is opened and the opening of the regulating switching valve is adjusted.

5. The energy-saving method for automatically adjusting and recovering waste heat from flue gas in a garbage power plant according to claim 1 is characterized in that: In step 2, the air heating system is provided with a regulating switching valve controlled by a PLC. By opening or closing the regulating switching valve of the front and rear connecting pipes of the air heating system, the air heating system heats the primary air or heats the garbage bin, or adjusts the heating amount of the air heating system.

6. The energy-saving method for automatically adjusting and recovering waste heat from flue gas in a garbage power plant according to claim 1 is characterized in that: The heat medium water in step 2 can also heat the heat exchange unit to increase the temperature of the deoxygenated water.

7. The energy-saving method for automatically adjusting and recovering waste heat from flue gas in a garbage power plant according to claim 1 is characterized in that: In step 1, after the flue gas heat exchange, there is also a cooling and washing process, which is to clean the solid particles and acidic substances in the flue gas by spraying alkaline water to reduce the pH value of the flue gas to meet the emission standards.

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