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 automatic adjustment and use of flue gas waste heat recovery of a garbage power plant, and solves the technical problems that an existing garbage incineration power plant is low in garbage incineration efficiency, the temperature of discharged flue gas is high, and heat of acid flue gas cannot be effectively utilized. A flue gas heat exchanger is arranged from the outlet of the bag-type dust collector to the middle section of the chimney for gas-water heat exchange, and sensible heat in flue gas is extracted to generate heat medium water; 2, the heating medium water is conveyed to a heat exchange unit through a pipeline, and temperature rising and heating of the deoxygenated water are achieved; and 3, the heat medium water subjected to heat exchange and cooling continues to provide heat for the air heating system, and primary air entering the garbage incinerator is heated or hot air entering the garbage bin is heated. The device can be widely applied to waste incineration occasions of waste incineration power plants.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of waste treatment, in particular to an energy-saving method for automatic adjustment of waste power plant flue gas waste heat recovery. BACKGROUND

[0002] After domestic waste enters the waste incineration power plant, the waste first needs to be continuously stacked by the waste crane, and after 5-7 days of fermentation at a certain temperature, the leachate is removed to improve the heat value, and then the waste can be incinerated. Due to the low temperature in autumn and winter, the stacking fermentation efficiency is low, the waste cannot be effectively fermented, the waste heat value is low, and 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 flue gas after waste incineration is strongly acidic, the flue gas temperature is high, and the heat cannot be effectively utilized. If the flue gas temperature is forcibly reduced, the flue gas will reach the acid dew point, which is easy to cause corrosion. At the same time, due to the use of dry / half-dry desulfurization in the waste incineration process, the desulfurization is not complete, which is also easy to cause chimney corrosion. The latest environmental protection requirement is to control the flue gas temperature of the incinerator within 45℃, therefore, how to reasonably utilize the waste incineration boiler flue gas waste heat and solve the problem of effective fermentation of waste in autumn and winter, reduce acid corrosion, has become a problem to be solved. SUMMARY

[0003] The present application provides an energy-saving method for automatic adjustment of waste power plant flue gas waste heat recovery to solve the technical problems of low waste incineration efficiency, high flue gas temperature, and ineffective utilization of acidic flue gas heat in the existing waste incineration power plant.

[0004] The present application provides an energy-saving method for automatic adjustment of waste power plant flue gas waste heat recovery, the specific steps comprising:

[0005] Step 1: Install a flue gas heat exchanger for gas-water heat exchange in the middle section between the bag filter outlet and the chimney, extract the sensible heat in the flue gas to produce heat medium water through the flue gas heat exchanger for gas-water heat exchange;

[0006] Step 2: The heat medium water is transported to the heat exchange unit through the pipeline to realize the heating of the deoxygenated water;

[0007] Step 3: The heat medium water after heat exchange and cooling continues to provide heat for the air heating system, heats the primary air entering the waste incinerator, or heats the hot air entering the waste bin.

[0008] Preferably, the flue gas after heat exchange in step 1 has a cooling and gas washing tower for cooling and acid removal process, which washes the solid particles and acidic substances in the flue gas by spraying alkaline liquid, reduces the ph value of the flue gas, and reaches the emission standard. The alkaline liquid is cooled and recycled by an independent cooling tower or a process cooling tower.

[0009] Preferably, the cooling gas washing tower is connected in parallel with a cooling gas washing tower bypass flue, and the cooling gas washing tower and the cooling gas washing tower bypass flue are respectively provided with valves for controlling the flow direction of the flue gas.

[0010] Preferably, the flue gas heat exchanger is connected with the chimney through an induced draft fan, and the induced draft fan is connected with the cooling gas washing tower through a condensing heat exchanger, which further extracts the latent heat of water vapor in the condensed flue gas, condenses and collects the sludge and acidic substances in the flue gas, reduces the temperature of the flue gas, and extracts heat, which can be used for heating the waste bin, social heating and plant heating, but is not limited thereto.

[0011] Preferably, the condensing heat exchanger is connected in parallel with a condensing heat exchanger bypass flue, and the acid-reducing gas washing tower and the condensing heat exchanger flue are connected in parallel with a common bypass flue, and the two ends of the condensing heat exchanger are provided with valves, and the top end of the acid-reducing gas washing tower is provided with a valve, and valves are installed on the secondary condenser bypass flue and the common bypass flue, and the flow direction of the flue gas is controlled by opening and closing the valves, and the condensing heat exchanger and the cooling gas washing tower are selected for use according to the emission index requirements or actual operation needs.

[0012] Preferably, when it is necessary to change the heated primary air or the hot air entering the waste bin in step 3, the opening and closing of the adjustment switching valve of the air heating system is controlled to change the air heating system to heat the primary air or the air entering the waste bin, so as to realize the distribution of heat.

[0013] Preferably, the hot air entering the waste bin is forcedly replaced with the cold air on the surface of the waste in the waste bin, and the replaced air is provided to the waste incinerator primary air fan for use as fresh air.

[0014] Preferably, the specific method of forcedly replacing the hot air entering the waste bin with the cold air on the surface of the waste in the waste bin is as follows:

[0015] Step 1), adjusting the direction of the jet flow rotating nozzle of the air replacement device according to the position of the waste in the waste bin; starting the push-pull motor, and the push-pull motor drives the arched push-pull rod to adjust the jet direction of each group of jet flow rotating nozzles;

[0016] Step 2), starting the jet flow rotating nozzle, and the boiler flue gas waste heat enters the jet flow rotating nozzle through the air duct, and the jet flow rotating nozzle sprays hot air into the waste bin after being aimed at the waste, the hot air stirs the cold air in the waste bin, and forced convection heat exchange is realized, the hot air is mixed with the cold air in the waste bin, the temperature of the waste bin is increased, and the water on the surface of the waste is taken away, and the waste is accelerated to heat and ferment;

[0017] Step 3), after the waste is transferred in the bin by the waste crane, the position of the accumulated waste changes, the position of the jet flow rotating nozzle is automatically adjusted, the jet flow rotating nozzle is aimed at the waste again, and steps 1) to 3) are repeated.

[0018] The present application has the following advantages:

[0019] The present application is provided with an air heating system in front of the boiler, a flue gas heat exchanger is installed in the middle section of the chimney from the outlet of the boiler induced draft fan, the flue gas filtered by the flue gas heat exchanger is subjected to gas-water heat exchange to generate heat medium water which is directly connected with the air heating system for circulating heat source, the air heating system uses the heat medium water to do gas-water heat exchange with the air sucked by the primary air fan, so that the temperature of the primary air can be effectively increased and the heat loss of the heated primary air can be reduced.

[0020] The flue gas heat exchanger also uses a switchable pipe network to heat the garbage in the garbage bin, when the garbage temperature in the garbage bin is too low due to weather changes, the garbage humidity is large, the heat value is low, and the boiler temperature rising is affected, the air heating system uses the heat medium water to heat the air to provide high-temperature hot air for the garbage bin, the high-temperature hot air enters the ejector through the air duct to forcibly convect and heat the cold air in the garbage bin and the surface of the garbage, so that the garbage temperature is increased, the drying and fermentation of the garbage are accelerated, the heat value of the garbage is increased, the addition of auxiliary fuel due to the ineffective fermentation of the garbage in winter is reduced, the energy loss is reduced, and the energy waste is avoided.

[0021] The present application is also provided with a deacidification gas tower between the flue gas heat exchanger and the chimney, the deacidification gas tower is an alkali solution deacidification tower, since the dry or semi-dry method is used for dust removal during garbage incineration, the acidic substances in the flue gas cannot be completely removed, the alkaline water is sprayed through the deacidification gas tower, the acidic substances in the flue gas can be removed again through the acid-base neutralization reaction, the ph value emission standard is met, the flue is protected, and the flue corrosion is prevented; at the same time, through the water washing mode, the flue gas temperature can be reduced to below 45℃, while 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 80mg / m 3 , and the 24-hour average emission concentration of hydrogen chloride is not higher than 8mg / m 3 . BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a structural schematic view of the energy-saving system in the incinerator according to Embodiment 1 of the present application;

[0023] Figure 2 is a flow process schematic view of the present application;

[0024] Figure 3 is a structural schematic view of the air replacement device according to the present application;

[0025] Figure 4 is a structural schematic view of the air replacement device according to the present application;

[0026] Figure 5 is a schematic diagram of the position of the air replacement device of the present application in a garbage bin;

[0027] Figure 6a is a process flow diagram of the energy-saving system of embodiment 2 of the present application after a bag-type dust collector of an incinerator;

[0028] Figure 6b is a structural schematic diagram of the energy-saving system of embodiment 2 of the present application after a bag-type dust collector of an incinerator;

[0029] Figure 7a is a process flow diagram of the energy-saving system of embodiment 3 of the present application after a bag-type dust collector of an incinerator;

[0030] Figure 7b is a structural schematic diagram of the energy-saving system of embodiment 3 of the present application after a bag-type dust collector of an incinerator;

[0031] Figure 8a is a process flow diagram of the energy-saving system of embodiment 4 of the present application after a bag-type dust collector of an incinerator;

[0032] Figure 8b is a structural schematic diagram of the energy-saving system of embodiment 4 of the present application after a bag-type dust collector of an incinerator.

[0033] Explanation of symbols in the drawings:

[0034] 1. air duct; 2. guardrail; 3. rack; 4. push-pull motor; 5. slide support; 6. jet rotary nozzle; 7. arched push-pull rod; 10. garbage pool; 20. incinerator; 21. feeding hopper; 22. chute; 30. desulfurization tower; 40. bag-type dust collector; 50. chimney; 600. acid-washing gas lowering tower; 601. flue gas heat exchanger; 602. induced draft fan; 603. first regulating switch valve; 604. second regulating switch valve; 605. third regulating switch valve; 606. circulating water pump; 607. air heating system; 608. fourth regulating switch valve; 609. fifth regulating switch valve; 610. air circulating fan; 611. sixth regulating switch valve; 612. seventh regulating switch valve; 613. deoxygenated water; 614. secondary condenser; 615. cooler; 616. cooling tower; 620. domestic heating pipe network; 621. garbage bin; 71. air suction port; 72. air waste heat recovery system; 73. primary air fan. DETAILED DESCRIPTION

[0035] The present application will be further described below in conjunction with the drawings and examples, so that those skilled in the art of the present application can easily implement the present application.

[0036] Example 1: as Figure 1As shown, the energy-saving system of the present application is a structural schematic diagram in incinerator / heat recovery boiler, the present application is according to the existing incinerator / heat recovery boiler, which is sequentially provided with garbage pool 10, incinerator 20, desulfurization tower 30, bag-type dust collector 40 and chimney 50, garbage pool 10 provides garbage incineration heat to incinerator 20 or heat recovery boiler through feeding hopper 21 and chute 22. After combustion, high-temperature flue gas enters the chimney after passing through desulfurization tower 30 and bag-type dust collector 40. The air in the garbage pool 10 enters the air heat recovery system 72 from the pipeline through the air suction port 71 and is heated to about 200 degrees Celsius, and then enters the incinerator 20 for combustion through the primary fan 73.

[0037] The present application is provided with induced draft fan 602 and flue gas heat exchanger 601 between bag-type dust collector 40 and chimney 50, induced draft fan 602 and flue gas heat exchanger 601 can be exchanged according to actual needs, cooperating with three regulating switch valves to control the opening and closing of flue gas heat exchanger 601 and the adjustment of flue gas volume, realizing waste heat recovery. Induced draft fan 602 guides the gas with heat discharged from bag-type dust collector 40 into flue gas heat exchanger 601 to heat the water in flue gas heat exchanger 601. First regulating switch valve 603 and second regulating switch valve 604 are connected in series at both ends of flue gas heat exchanger 601, and third regulating switch valve 605 is connected in parallel with first regulating switch valve 603, second regulating switch valve 604 and flue gas heat exchanger 601. When it is needed to stop using flue gas heat exchanger 601, first regulating switch valve 603 and second regulating switch valve 604 are closed, and third regulating switch valve 605 is opened. Conversely, when it is needed to start using flue gas heat exchanger 601, first regulating switch valve 603 and second regulating switch valve 604 are opened, and third regulating switch valve 605 is closed. When it is needed to adjust the flue gas volume, first regulating switch valve 603, second regulating switch valve 604 and third regulating switch valve 605 are all opened, and the opening degree of third regulating switch valve 605 is adjusted to control the flue gas volume.

[0038] The water heated by the flue gas heat exchanger 601 enters the air heating system 607 through the circulating water pump 606 to provide 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, improve the overall boiler efficiency, and save energy consumption. The air heating system 607 is in communication with the air suction port 71, the air circulation fan 610, and the air waste heat system 72 through multiple adjusting and switching valves. One end of the air heating system 607 is connected to the sixth adjusting and switching valve 611 for opening or closing the air entering the air heating system 607. The other end is connected to the fourth adjusting and switching valve 608 and the fifth adjusting and switching valve 609, respectively. The fourth adjusting and switching valve 608 is in communication with the air duct 1 through the air circulation fan 610 to provide heat for the garbage bin 10. The fifth adjusting and switching valve 609 is in communication with the air waste heat system 72 to heat the primary air of the boiler. The seventh adjusting and switching valve 612 is connected in parallel with the air heating system 607 and can be used to close the air heating system 607 during maintenance.

[0039] After the flue gas passes through the flue gas heat exchanger 601, the temperature of the flue gas decreases 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, an acid reduction and gas washing tower 600 is arranged between the second adjusting and switching valve 604 of the flue gas heat exchanger 601. The acid reduction and gas washing tower 600 is used to wash and cool the flue gas after the temperature is reduced by the flue gas heat exchanger 601, to wash out solid particles and sulfur dioxide, nitrogen oxides, and other acidic substances in the flue gas, to reduce pollutants in the flue gas through acid-base neutralization reaction, and to reduce the temperature of the flue gas to ensure compliance with the latest environmental protection requirements. The flue gas enters the acid reduction and gas washing tower 600, is cooled through multiple sprayings, absorbs solid particles and water after acid-base neutralization reaction, is reused through heat dissipation, filtration, and other operations, reenters the spray head for water washing again, and is discharged into the chimney 50 after the temperature of the flue gas after water washing is lower than 45 degrees Celsius. When the temperature is low in autumn and winter, the garbage bin 10 needs to be heated, the flue gas heat exchanger 601 is started, the first adjusting and switching valve 603 and the second adjusting and switching valve 604 are opened, and the third adjusting and switching valve 605 is closed. The flue gas heat exchanger 601 absorbs the waste heat in the high-temperature flue gas, the heated water enters the air heating system 607 through the circulating water pump 606, the fifth adjusting and switching valve 609 and the seventh adjusting and switching valve 612 are closed, the fourth adjusting and switching valve 608 and the sixth adjusting and switching valve 611 are opened, the air circulation fan 610 sucks air from the air suction port 71, the air enters the air heating system 607 through the sixth adjusting and switching valve 611 for heating, enters the air replacement device of the garbage bin 10 through the fourth adjusting and switching valve 608, the hot air is sprayed to the garbage bin by the jet rotating spray head 6, the hot air stirs the cold air in the garbage bin, forced convection heat exchange is achieved, the hot air mixes with the cold air in the garbage bin, the temperature of the garbage bin is increased, and the surface moisture of the garbage is taken away to accelerate the drying of the garbage.

[0040] When the temperature rises in spring and summer, when the garbage bin does not need to be heated, the air circulation fan 610, the fourth adjusting switch valve 608 and the seventh adjusting switch valve 612 are closed, the sixth adjusting switch valve 611 and the fifth adjusting switch valve 609 are opened, the primary air fan 73 extracts air from the air suction port 71, the air is heated to about 80 degrees Celsius by the sixth adjusting switch valve 611 and the air heating system 607, then enters the air waste heat collector system 72 from the fifth adjusting switch valve 609 for further heating, and reaches about 200 degrees Celsius to enter the primary air fan 73 for combustion in the boiler.

[0041] According to the seasons or actual needs, the waste heat in the chimney 50 is recycled and utilized to provide heat for the garbage bin 10 or assist the air waste heat collector system 72 to heat the air, thereby reducing the heat demand of the air waste heat collector system 72. PLC is used to control the adjusting switch valves, circulating water pumps and other equipment, so as to quickly adjust the running direction of air, water flow and flue gas, and realize automatic control.

[0042] For the flue gas heat exchanger 601 that provides heat, the heat can also be provided to other places that need to be heated, for example, the hot water output by the flue gas heat exchanger 601 can be used to heat the heat exchange unit, so as to realize the heating of deoxidized water. Similarly, the air circulation fan 610 can also collect heat from other structures according to actual needs to heat the air.

[0043] As shown in the flowchart of the energy-saving method of the present application, the specific steps of the present application include: Figure 2

[0044] Step 1: A flue gas heat exchanger is installed in the middle section of the induced draft fan outlet to the chimney for gas-water heat exchange, and hot medium water is generated by the gas-water heat exchange of the flue gas heat exchanger. After the flue gas heat exchange, the flue gas needs to be cooled and washed to reduce the ph value of the flue gas and meet the emission standard.

[0045] Step 2: The hot medium water is directly connected to the air heating system for circulating heat source, and the air heating system uses the hot medium water and the sucked air for gas-water heat exchange.

[0046] Step 3: The exchanged hot air is provided to the primary air fan as a heat source to increase the temperature of the primary air, or according to the change of the weather, the temperature of the garbage in the garbage bin is too low to freeze, the humidity is high, and the heat quality is low to affect the temperature rise of the boiler. The exchanged hot air can also be adjusted and provided to the air circulation fan to provide high-temperature hot air to the garbage bin for replacement, so that the temperature of the garbage and the space in the bin is increased.

[0047] Step 4: The hot air is delivered to the jet rotating nozzle provided in the garbage bin through the air duct, and the hot air is sprayed to replace the surface of the garbage and the cold air in the bin. The replaced air is provided to various fans as fresh air. ​

[0048] The specific method of hot air jetted by the jet rotating nozzle in the garbage bin to replace cold air is:

[0049] Step 1), adjust the direction of the jet rotating nozzle of the air replacement device according to the position of the garbage in the garbage bin; start the push-pull motor, and the push-pull motor drives the arched push-pull rod to adjust the jetting direction of each group of jet rotating nozzles;

[0050] Step 2), start the jet rotating nozzle, and the boiler flue gas waste heat enters the jet rotating nozzle through the air duct, and the jet rotating nozzle sprays hot air to the garbage bin after being aligned with the garbage, the hot air stirs the cold air in the garbage bin, and the hot air and the cold air in the garbage bin are mixed to improve the temperature of the garbage bin and take away the moisture on the surface of the garbage, and accelerate the drying of the garbage;

[0051] Step 3), after the garbage is transferred in the bin by the garbage crane, the position of the accumulated garbage changes, the position of the jet rotating nozzle is adjusted, the jet rotating nozzle is aligned with the garbage again, and steps 1) to 3) are repeated.

[0052] As Figures 3-5 , the air replacement device structure diagram of the garbage bin of the present application, a plurality of groups of jet replacement devices are uniformly distributed on the air duct 1 in communication with the hot air of the boiler flue gas waste heat exchanger, each group of jet replacement devices is provided with a rack 3 and a jet rotating nozzle 6, the rack 3 is fixed on the air duct 1, the jet rotating nozzle 6 is fixed on the air duct 1 and communicates with the air duct 1 inside. The push-pull motor 4 is fixed on the rack 3, the push-pull motor 4 is hinged with the arched push-pull rod 7, the arched push-pull rod 7 is connected with the spherical jet rotating nozzle 6, and the push-pull motor 4 drives the direction change of the jet rotating nozzle 6 when it operates. The air duct 1 is also provided with a slide support 5 for guiding the arched push-pull rod 7, one end of the slide support 5 is fixed on the air duct 1, the other end is provided with a circular ring, the circular ring is sleeved with the arched push-pull rod 7, and is used for guiding the sliding direction of the arched push-pull rod 7.

[0053] The air duct 1 is arranged inside or outside the garbage bin as needed, such as being arranged outside the garbage bin, then being communicated with the jet rotating nozzle 6 through the branch pipe on the air duct 1, and the direction of the jet rotating nozzle 6 is directly controlled by the motor to forcibly exchange heat in the garbage bin and heat the garbage.

[0054] Example 2: as Figure 6a, b shows the process flow diagram and structural schematic diagram of the energy saving system after the bag filter of the incinerator in this embodiment. This embodiment is generally used for temporary operation in summer operation or maintenance state. The energy saving system in this embodiment is provided with a flue gas heat exchanger 601 between the bag filter 40 and the induced draft fan 602. After heat exchange in the flue gas heat exchanger 601, the heat exchanged is used for heating the deoxygenated water 613 and the primary air of the waste incineration boiler, so as to improve the deoxygenated water and the primary air temperature of the waste incineration boiler and improve the combustion efficiency of the waste incineration boiler. After the flue gas in the waste incineration boiler passes through the bag filter 40, the flue gas enters the flue gas heat exchanger 601 for heat exchange and cooling. After the flue gas is cooled, the flue gas is directly discharged into the chimney 50 by the induced draft fan 602. At this time, the flue gas heat exchanger 601 (primary heat exchanger) is generally operated at a temperature higher than the dew point temperature of the flue gas to avoid corrosion of the chimney 50.

[0055] Embodiment 3: as Figure 7a , b shows the process flow diagram and structural schematic diagram of the energy saving system after the bag filter of the incinerator in this embodiment. This embodiment is used for the waste power plant flue gas cooling and emission 45℃ waste heat recovery process. The embodiment adds a deacidification washing tower 600 and a cooler 615. The deacidification washing tower 600 is arranged at the rear end of the induced draft fan 602, and the cooler 615 is arranged at the top of the deacidification washing tower 600. The deacidification washing tower 600 uses alkaline liquid to wash and cool the flue gas cooled by the flue gas heat exchanger 601, so as to wash out the solid particles and acidic substances such as sulfur dioxide and nitrogen oxides in the flue gas, reduce the pollutants in the flue gas through acid-base neutralization reaction, and reduce the flue gas temperature.

[0056] After the flue gas is cooled by multiple spraying, the flue gas enters the cooler 615 for further cooling. After heat exchange in the cooler 615, the hot water enters the cooling tower 616 for cooling and then is recycled. After the flue gas is reduced to below 45℃ which meets the latest environmental protection requirements, the flue gas is discharged into the chimney 50. The cooling tower 616 can be an independent cooling tower or can use the existing process cooling tower in the waste power plant.

[0057] The induced draft fan 602 is provided with two branches. One is a bypass flue directly connected to the chimney, and the other is a flue connected to the deacidification washing tower 600. The two branches are respectively controlled by valves. When the flue gas needs to be cooled and deacidified, the valve directly connected to the chimney is closed, the flue gas enters the deacidification washing tower 600 for treatment; when the deacidification washing tower 600 and / or the cooler 615 need to be maintained, the front valve connected to the deacidification washing tower 600 and the top valve connected to the chimney of the deacidification washing tower 600 are closed, and the bypass flue valve directly connected to the chimney is opened, so that the flue gas is discharged. The valve can be manually or automatically controlled to realize the flow of the flue gas in the bypass channel.

[0058] Embodiment 4: as Figure 8a, b shown is the process flow chart and structural schematic diagram of the energy saving system of the present embodiment after the bag filter of the incinerator, the present embodiment is aimed at the winter operation mode, the waste incineration flue gas cooling and discharging 45℃ waste heat recovery process, which connects the waste incinerator waste heat with the domestic heating pipe network, and the hot water enters the domestic heating pipe network after heat exchange, and the residents are heated in winter. The present embodiment increases the secondary condenser 614 on the basis of embodiment 3, the secondary condenser 614 is installed between the induced draft fan 602 and the acid washing gas tower 600, the secondary condenser 614 continues to exchange heat with the flue gas after heat exchange in the flue gas heat exchanger 601, further extracts the latent heat in the flue gas, recycles the heat of the condensed water vapor, and provides heat for the domestic heating pipe network 620 and the waste bin 621. In the secondary condenser 614 (condensing heat exchanger), the flue gas is further cooled and water vapor is condensed, which is used for heating the waste bin, social heating and plant heating, etc., which significantly improves the overall thermal energy utilization efficiency of the system.

[0059] The present embodiment has a secondary condenser bypass flue in parallel with the secondary condenser 614, and a public bypass flue is connected in parallel with the flue of the acid washing gas tower 600 and the secondary condenser 614. Valves are provided at the front and rear ends of the secondary condenser 614, and a valve is provided at the top end of the acid washing gas tower 600. Valves are installed on the secondary condenser bypass flue and the public bypass flue. By opening and closing the valves, the direction of the flue gas can be controlled.

[0060] The opening and closing of the acid washing gas tower 600 and the secondary condenser 614 are selected according to the emission index requirements or actual operation needs, and the opening and closing of the acid washing gas tower 600 and the secondary condenser 614 are realized by the selection of the valves. For example, when there is no social heating demand, the latent heat in the flue gas can be extracted, the valves before and after the secondary condenser 614 can be closed, the secondary condenser bypass flue can be opened, and the flue gas can directly enter the acid washing gas tower 600 for cooling and acid removal treatment. When the acid washing gas tower 600 and the secondary condenser 614 need to be repaired or replaced, the valves before and after the acid washing gas tower 600 and the secondary condenser 614 are closed, and the public bypass flue is opened to discharge the flue gas, so as to avoid the shutdown of the entire waste incinerator.

[0061] The secondary condenser 614 is made of acid and alkali corrosion resistant material, and the bottom of the secondary condenser 614 is provided with an alkali precipitation tank for neutralizing the acidic liquid formed by the secondary condenser 614.

[0062] The present application is first used for heat waste heat recovery of the flue gas of the garbage power plant, generates economic benefits. Secondly, the ultra-low emission of flue gas temperature is realized, the acid emission is reduced, the social benefits are generated, and the corrosion of the equipment is avoided. The step-by-step deacidification operation mode is adopted, and the operation cost during the garbage incineration treatment is reduced. The present application constructs a low-temperature emission and deep treatment system, and the target is to realize the stable control of the flue gas temperature below 45 DEG C while ensuring the stable operation of the system, realize the double targets of deep gradient utilization of heat and collaborative reduction of pollutants. In the summer working condition, the system mainly operates the primary heat exchanger (flue gas heat exchanger), extracts sensible heat from high-temperature flue gas for deoxygenated water heating and primary air preheating, and meets the basic thermal load of the boiler system. Since the social heating demand is low at this stage, the secondary condenser and the acid reduction gas washing tower are usually in the state of shutdown, and the system orderly dissipates the redundant heat through the cooling tower to maintain the overall heat balance and system safety. If there is a specific tail gas emission control requirement in summer, the system can selectively open the tail gas washing unit to further enhance the pollutant removal capacity.

[0063] In the winter operation mode, the flue gas successively passes through the primary heat exchanger (flue gas heat exchanger) and the condensing heat exchanger (secondary condenser), realizing the gradient recovery of'sensible heat-potential heat'. Among them, the primary heat exchanger (flue gas heat exchanger) is still responsible for the heating task of deoxygenated water and primary air; the condensing heat exchanger further reduces the flue gas temperature below the dew point, deeply recovers the latent heat, and the output low-temperature hot water is used for garbage bin heating and urban central heating and other external load scenarios. At the same time, all tail gas is treated through the tail gas washing tower to realize the liquid-phase collaborative removal of pollutants in the low-temperature and high-humidity environment, and ensure to meet the environmental protection emission standard.

[0064] The present application is optimized in structure design, and the induced draft fan is moved between the primary heat exchanger (flue gas heat exchanger) and the condensing heat exchanger, which effectively reduces the flue gas temperature and volume flow entering the induced draft fan, thereby significantly reducing the power demand and operation energy consumption of the induced draft fan, and improving the energy-saving level of the overall system.

[0065] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the scope defined by the claims of the present application shall be within the protection scope of the present application.

Claims

1. An energy-saving method for automatic regulation of waste heat recovery from flue gas in a waste-to-energy plant, characterized in that, The specific steps include: Step 1: Install a flue gas heat exchanger in the middle section from the outlet of the bag filter to the chimney to perform gas-water heat exchange. The sensible heat in the flue gas is extracted to generate heat transfer medium water through the gas-water heat exchanger. Step 2: The heat transfer medium is transported to the heat exchange unit through pipelines to heat the deoxygenated water. Step 3: After the heat exchange and cooling process, the hot water continues to provide heat to the air heating system, heating the primary air entering the waste incinerator or the hot air entering the waste bin.

2. The energy-saving method for automatic regulation of waste heat recovery from waste-to-energy plants according to claim 1, characterized in that, In step 1, after the flue gas heat exchange, there is a cooling gas scrubbing tower for the cooling gas scrubbing and acid removal process. The tower uses alkaline liquid to clean solid particles and acidic substances in the flue gas, thereby reducing the pH value of the flue gas and meeting emission standards. The alkaline liquid is cooled and recycled through an independent cooling tower or a process cooling tower.

3. The energy-saving method for automatic regulation of waste heat recovery from waste-to-energy plants according to claim 2, characterized in that, The cooling gas scrubbing tower is connected in parallel with a cooling gas scrubbing tower bypass flue, and valves controlling the direction of flue gas are respectively installed before and after the cooling gas scrubbing tower and in the cooling gas scrubbing tower bypass flue.

4. The energy-saving method for automatic regulation of waste heat recovery from waste-to-energy plants according to claim 2, characterized in that, An induced draft fan is provided between the flue gas heat exchanger and the chimney, and a condensing heat exchanger is provided between the induced draft fan and the cooling scrubbing tower. The condensing heat exchanger further extracts the latent heat of water vapor in the condensed flue gas and condenses and collects sludge and acidic substances in the flue gas, thereby reducing the flue gas temperature. The uses of the extracted heat include, but are not limited to, heating of waste storage areas, community heating, and factory heating.

5. The energy-saving method for automatic regulation of waste heat recovery from waste-to-energy plants according to claim 4, characterized in that, The condensing heat exchanger is connected in parallel with a condensing heat exchanger bypass flue. The acid-reducing scrubbing tower and the condensing heat exchanger flue are connected in parallel with a common bypass flue. Valves are provided at both ends of the condensing heat exchanger and at the top of the acid-reducing scrubbing tower. Valves are also installed on the secondary condenser bypass flue and the common bypass flue. The direction of the flue gas is controlled by opening and closing the valves. The opening and closing of the condensing heat exchanger and the cooling scrubbing tower are selected according to the emission index requirements or actual operation needs.

6. The energy-saving method for automatic regulation of waste heat recovery from waste-to-energy plants according to claim 1, characterized in that, In step 3, when it is necessary to change the heating of primary air or the heating of hot air entering the waste bin, the opening and closing of the regulating switching valve on the air heating system is controlled to change the heating of primary air or the heating of air entering the waste bin, thereby achieving heat distribution.

7. The energy-saving method for automatic regulation of waste heat recovery from waste-to-energy plants according to claim 1, characterized in that, The hot air entering the waste bin is forcibly replaced by the cold air on the surface of the waste inside the bin. The replaced air is then supplied to the primary air fan of the waste incinerator as fresh air.

8. The energy-saving method for automatic regulation of waste heat recovery from waste-to-energy plants according to claim 7, characterized in that, The specific method for forcibly separating the hot air entering the waste bin from the cold air on the surface of the waste inside the waste bin is as follows: Step 1): Adjust the direction of the jet rotating nozzle of the air replacement device according to the position of the garbage in the garbage bin; start the push-pull motor, which drives the arched push-pull rod to adjust the spray direction of each group of jet rotating nozzles; Step 2) Activate the jet rotary nozzle to introduce the waste heat from the boiler flue into the jet rotary nozzle through the air duct. After the jet rotary nozzle is aimed at the garbage, it sprays hot air into the garbage bin. The hot air agitates the cold air inside the garbage bin, forcing convection heat exchange. The hot air mixes with the cold air in the garbage bin, raising the temperature of the garbage bin and removing moisture from the surface of the garbage, thus accelerating the heating and fermentation of the garbage. Step 3): After the garbage crane moves the garbage to a different position inside the bin, the position of the accumulated garbage changes, and the position of the jet rotating nozzle is automatically adjusted to aim the jet rotating nozzle at the garbage again for spraying, repeating steps 1) to 3).

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