Energy-saving waste incineration flue gas purification device and purification process

Abstract

The invention discloses an energy-saving type waste incineration flue gas purification device and a purification process. According to the energy-saving type waste incineration flue gas purification device, through combination of the incinerator, the waste heat boiler, the dust removal device, the SCR device, the GGH device and the like, multi-stage purification and energy recovery of flue gas are achieved. And through the arrangement of the dry method device and the SNCR device in the furnace, preliminary deacidification and denitration can be conducted in the incineration process, and the burden of follow-up treatment is reduced. The condensation heat exchanger is introduced, so that sensible heat and latent heat in the flue gas are further utilized, the energy utilization efficiency is improved, and the energy consumption is reduced. According to the invention, the contradiction between heating for denitration and cooling for deacidification is solved, the waste heat of the flue gas is recovered, and heat is transferred to the SCR in a coupling manner; pollutants are efficiently removed, ultralow emission is achieved, latent heat and sensible heat of flue gas are fully utilized, and the energy utilization rate is effectively increased.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas treatment, especially the technical field of waste incineration flue gas purification. Specifically, it is an energy-saving waste incineration flue gas purification device and purification process. Background Art

[0002] The pollutants in waste incineration flue gas mainly include particulate matter (such as fly ash, soot), acidic gases (such as sulfur dioxide, hydrogen chloride), nitrogen oxides, heavy metals (such as lead, mercury, cadmium), organic pollutants (such as dioxins, etc.) and greenhouse gases (such as carbon dioxide). Common waste incineration deacidification methods mainly include wet method, dry method and semi-dry method. The wet method has high deacidification efficiency, and the removal efficiency of HCl can reach more than 99%, and the removal efficiency of SO2 can also reach more than 95%. A large amount of wastewater is generated, and a wastewater treatment device needs to be configured; however, the temperature of the flue gas after deacidification is relatively low, and a flue gas reheating device needs to be equipped to prevent chimney corrosion and white smoke emission. The dry method has small investment, simple equipment, convenient maintenance and is not easy to block. However, the contact time between the solid and liquid phases is short, and more drugs are required; the purification efficiency is relatively low. The semi-dry method combines the advantages of the dry method and the wet method, with high deacidification efficiency (90% - 99%), simple equipment and stable operation. The technical route is mature and rarely produces sewage discharge. However, it has high requirements for the operation level, and the residence time and the temperature difference between the inlet and outlet of the reaction tower need to be strictly controlled. Common waste incineration denitrification methods mainly include selective non-catalytic reduction (SNCR), selective catalytic reduction (SCR) and SNCR / SCR combined technology. The SNCR technology does not require a catalyst, has low equipment cost and simple operation, but the denitrification efficiency is limited (30% - 65%), has strict requirements for the reaction temperature, and has a high ammonia slip, which is easy to cause secondary pollution. The SCR technology has high denitrification efficiency (up to more than 90%), low ammonia slip and strong adaptability to flue gas conditions, but the catalyst cost is high and heating is required. The SNCR / SCR combined technology combines the advantages of both, with high denitrification efficiency (80% - 90% and above), reduced catalyst dosage, but the system is complex, and the investment and maintenance costs are also relatively high. For the removal of dioxins, heavy metals and dust, the commonly used method is dry activated carbon + dust collector.

[0003] At present, the conventional process route for waste incineration is SNCR + semi-dry method + dry method + bag filter. This system can achieve a certain degree of pollutants, with a simple process chain and mature technology, but it cannot achieve ultra-low emissions. To achieve ultra-low emissions, SCR and wet method must be added on this basis. There are two current ultra-low emission process routes. One is SNCR + semi-dry method + dry method + bag filter

[0004] + SGH + SCR + GGH + wet method, and the other is SNCR + semi-dry method + dry method + bag filter + GGH1 + wet method + GGH2 + SGH + SCR.

[0005] However, the above two emission process routes have the following disadvantages:

[0006] (1) For the SNCR + semi-dry method + dry method + bag filter + SGH + SCR + GGH + wet method process route, the semi-dry method is used as the main means of acid removal first. During the process, water is sprayed to cool down, and the energy is transferred to the latent heat in the flue gas. Subsequently, the SCR denitrification step requires reheating after the semi-dry method, which leads to unnecessary energy consumption, increases the operating cost, and reduces the overall energy efficiency. At the end, the wet method also sprays water to the saturated state, which causes a large amount of energy waste, and a large amount of heat is transferred to the latent heat in the flue gas;

[0007] (2) For the SNCR + semi-dry method + dry method + bag filter + GGH1 + wet method

[0008] +GGH2 + SGH + SCR process, the semi-dry method is also used as the main means of acid removal first. During the process, water is sprayed to cool down, and the energy is transferred to the latent heat in the flue gas. Then, the wet method cools down again. After two coolings, the process combination of GGH2 + SGH is used to heat up, which further leads to unnecessary energy consumption, increases the operating cost, and reduces the overall energy efficiency. Summary of the Invention

[0009] The technical problem to be solved by the present invention is: to overcome the deficiencies in the prior art and provide an energy-saving waste incineration flue gas purification device and purification process. The present invention solves the contradiction between the need for heating up in denitrification and the need for cooling down in acid removal, and recovers the waste heat of the flue gas, coupling heat transfer to SCR; while efficiently removing pollutants and achieving ultra-low emissions, it makes full use of the latent heat and sensible heat of the flue gas, effectively improving the energy utilization rate.

[0010] The technical solution adopted by the present invention to solve its technical problems is:

[0011] An energy-saving waste incineration flue gas purification device is successively provided with an incinerator, a waste heat boiler, a dust removal device, an SCR device, a GGH1 device, a GGH2 device, a GGH3 device, an induced draft fan and a chimney along the waste incineration flue gas traveling route. The incinerator is connected with an air preheater that provides air to the incinerator;

[0012] It further includes an in-furnace dry method device and an SNCR device. The in-furnace dry method device sprays acid removal agent powder into the furnace chamber of the incinerator, and the SNCR device sprays denitrification agent powder into the waste heat boiler flue;

[0013] It also includes a heat exchange component that utilizes the sensible heat and latent heat in the flue gas. The heat exchange component includes a condensation heat exchanger, which is provided with an air inlet, an air outlet, a flue gas inlet, and a flue gas outlet. The air outlet of the condensation heat exchanger is connected to the GGH1 device through a pipeline, and the air outlet of the GGH1 device is connected to the air inlet of the SCR device through a pipeline. The GGH1 device supplies dilution air and sealing air to the SCR device.

[0014] Through the combination of an incinerator, a waste heat boiler, a dust removal device, an SCR device, a GGH device, etc., multi-stage purification and energy recovery of the flue gas are achieved. The setting of the in-furnace dry process device and the SNCR device can initially remove acid and nitrogen oxides during the incineration process, reducing the burden of subsequent treatment. The introduction of the condensation heat exchanger further utilizes the sensible heat and latent heat in the flue gas, improving the energy utilization efficiency and reducing energy consumption.

[0015] Furthermore, the dust removal device includes an activated carbon device and a bag filter. The feed end of the activated carbon device is connected to the discharge end of the waste heat boiler, the discharge end of the activated carbon device is connected to the feed end of the bag filter, and the discharge end of the bag filter is connected to the feed end of the SCR device.

[0016] Through the combination of the activated carbon device and the bag filter, heavy metals and dust in the flue gas can be effectively removed, ensuring that the flue gas has been preliminarily purified before entering the SCR device, reducing the load on the SCR device and extending its service life.

[0017] Furthermore, this energy-saving waste incineration flue gas purification device also includes a wet scrubber. The flue gas inlet of the wet scrubber is connected to the flue gas outlet of the GGH2 device, the flue gas outlet of the wet scrubber is connected to the flue gas inlet of the condensation heat exchanger, and the flue gas outlet of the condensation heat exchanger is connected to the GGH2 device through a pipeline.

[0018] The setting of the wet scrubber further enhances the acid removal effect. Especially after the GGH2 device, acidic substances in the flue gas are further removed, ensuring that the discharged flue gas meets environmental protection standards. The use of the condensation heat exchanger also further recovers the heat in the flue gas, improving the energy utilization rate.

[0019] Furthermore, the GGH3 device is provided with an air inlet and an air outlet. The air outlet of the GGH3 device is connected to the air inlet of the air preheater through a pipeline.

[0020] The setting of the GGH3 device enables the flue gas to exchange heat with the primary air, further recovering the heat in the flue gas, reducing the final discharge temperature of the flue gas, and at the same time increasing the temperature of the primary air entering the incinerator, reducing the energy consumption of the incinerator.

[0021] An energy-saving waste incineration flue gas purification process, the purification process uses the above-mentioned energy-saving waste incineration flue gas purification device, and the purification process specifically includes the following steps:

[0022] Step S1: The incinerator uses the 200°C air from the air preheater as the primary air. The flue gas generated is first preliminarily deacidified by the in-furnace dry process device to reduce the concentration of acidic pollutants.

[0023] Step S2: After preliminary deacidification, it is then preliminarily denitrified by the SNCR device in a flue.

[0024] Step S3: After passing through the waste heat boiler, the temperature of the flue gas after preliminary denitrification is controlled at about 190°C.

[0025] Step S4: The flue gas at the outlet of the waste heat boiler passes through the activated carbon device and the bag filter to remove heavy metals and dust.

[0026] Step S5: The flue gas at the outlet of the bag filter goes to the SCR device for further denitrification. The outlet temperature of the flue gas from the bag filter is 185°C. The SCR device uses the 170°C air from the GGH1 device as the dilution air and the seal air.

[0027] Step S6: The flue gas at the outlet of the SCR device enters the GGH1 device to exchange heat with the air from the condensation heat exchanger, and the temperature is reduced to 165°C. The GGH1 device simultaneously heats the air from the condensation heat exchanger from 60°C to 170°C, and the heated air goes to the SCR device.

[0028] Step S7: The flue gas at the outlet of the GGH1 device enters the GGH2 device to exchange heat with the deacidified clean flue gas from the condensation heat exchanger, and the temperature is reduced to 95°C.

[0029] Step S8: The dirty flue gas at the outlet of the GGH2 device enters the wet scrubber for further deacidification. The moisture in the dirty flue gas increases to near the saturation state, and the temperature is reduced to 60 - 65°C.

[0030] Step S9: The clean flue gas at the outlet of the wet scrubber enters the condensation heat exchanger for heat exchange, using the sensible heat and latent heat in the flue gas to heat the incoming air. After the air rises to 60°C, it goes to the GGH1 device.

[0031] Step S10: The clean flue gas after the condensation heat exchanger goes to the GGH2 device to exchange heat with the dirty flue gas from the GGH1 device, and the temperature rises to 120°C.

[0032] Step S11: The clean flue gas heated by the GGH2 device enters the GGH3 device to exchange heat with the primary air. The temperature of the flue gas drops to 55°C, and the primary air rises to 115°C. The primary air is heated to 200°C again by passing through the air preheater and then sent to the incinerator.

[0033] Step S12: The flue gas after heat exchange in the GGH3 device is drawn away by the induced draft fan and discharged from the chimney.

[0034] The above process ensures the efficient purification of flue gas and the full utilization of energy through multi-stage deacidification, denitrification, dust removal, and energy recovery. The entire process is reasonably designed, capable of effectively reducing pollutant emissions while improving energy utilization efficiency.

[0035] Furthermore, air at 20 - 40°C is introduced at the air inlet of the GGH3 device. Introducing air at 20 - 40°C at the air inlet of the GGH3 device ensures the maximization of heat exchange efficiency and avoids equipment damage or efficiency decline caused by too high or too low temperature.

[0036] Furthermore, air at 20 - 40°C is introduced at the air inlet of the condensation heat exchanger. Introducing air at 20 - 40°C at the air inlet of the condensation heat exchanger ensures that the heat exchanger can efficiently recover the heat in the flue gas and avoids the decline of heat exchange efficiency caused by too high air temperature.

[0037] Furthermore, the temperature of the flue gas at the outlet of the SCR device is 180°C. The temperature of the flue gas at the outlet of the SCR device being 180°C ensures that the SCR device operates within the optimal temperature range, improves denitrification efficiency, and avoids catalyst deactivation or efficiency decline caused by too high or too low temperature.

[0038] The beneficial effects of the present invention are as follows: The present invention is reasonably designed and has the following advantages:

[0039] (1) By combining the in - furnace dry process device and the SCR device and arranging them before the wet deacidification process, the SGH of the SCR device (which must be installed in the prior art) is omitted; the contradiction between the need for temperature increase during denitrification and the need for temperature decrease during deacidification is solved; by omitting the additional energy consumption required for denitrification temperature increase, the overall operating cost is effectively reduced;

[0040] (2) The dilution air and sealing air of the SCR device are heated through the condensation heat exchanger and the GGH1 device, thus avoiding the energy consumption required for heating these airs, reducing energy waste, and lowering the operating cost;

[0041] (3) The flue gas at the outlet of the wet tower first enters the condensation heat exchanger and then the GGH2 device, reducing the moisture in the flue gas, utilizing the latent heat and sensible heat of the flue gas, improving energy utilization efficiency, while reducing the pollutant concentration, solving the negative effects brought by wet spraying, and reducing the possibility of white fog in the flue gas;

[0042] (4) The flue gas is first cooled and the moisture is removed through the condensation heat exchanger, which creates conditions for finally reducing the flue gas temperature to 55°C, and effectively avoids the precipitation of acidic moisture in the induced draft fan and chimney, thereby reducing the risk of corrosion of the induced draft fan and chimney caused by acidic moisture;

[0043] (5) The GGH3 device transfers the final heat of the system to the primary air, reducing the flue gas outlet temperature to 55°C, maximizing the utilization of the waste heat in the flue gas.

[0044] (6) Three GGHs and a condensation heat exchanger are adopted to cascade-utilize the sensible heat and latent heat in the flue gas, minimizing the emission temperature and featuring high energy utilization efficiency. Description of the Drawings

[0045] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0046] Figure 1 It is a schematic structural diagram of an energy-saving waste incineration flue gas purification device in the present invention.

[0047] In the figure: 1. Incinerator; 2. In-furnace dry method device; 3. SNCR device; 4. Waste heat boiler; 5. Activated carbon device; 6. Bag filter; 7. SCR device; 8. GGH1 device; 9. GGH2 device; 10. GGH3 device; 11. Induced draft fan; 12. Chimney; 13. Wet scrubber; 14. Condensation heat exchanger; 15. Air preheater. Specific Embodiments

[0048] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0049] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless otherwise clearly specified in the context, the singular form also includes the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0050] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0051] Glossary:

[0052] Overview of the incinerator: The incinerator is a key equipment for the harmless treatment of garbage or biomass. Its core mechanism is to decompose the organic matter in solid waste through a high-temperature environment (usually in the temperature range of 850°C to 1100°C), converting it into harmless gases, water vapor and ash residues.

[0053] Flue gas: Here, the flue gas specifically refers to the gases, particulate pollutants and their mixtures released during the incineration of garbage or biomass. The main pollutants in the flue gas from garbage incineration include particulate matter (such as fly ash, soot), acidic gases (such as sulfur dioxide, hydrogen chloride), nitrogen oxides, heavy metals (such as lead, mercury, cadmium), organic pollutants (such as dioxins, etc.) and greenhouse gases (such as carbon dioxide).

[0054] Dry process in the furnace: This technology involves adding desulfurizing agents such as limestone and gypsum in the incinerator. These additives chemically react with the sulfur dioxide generated during combustion at high temperatures to form soluble calcium-sulfur compounds such as calcium sulfate, thereby effectively achieving the purpose of acid removal.

[0055] Waste heat boiler: The waste heat boiler is the core equipment of the waste heat recovery system for garbage incineration. It uses the high-temperature flue gas generated by the incinerator to pass through the heating surface, transferring heat energy to the water in the boiler to turn the water into high-temperature and high-pressure steam.

[0056] SNCR: A selective, non-catalytic flue gas denitrification method. It directly injects a reducing agent containing ammonia radicals (such as urea solution, ammonia water solution, etc.) into the flue or secondary flue of the incinerator under high-temperature conditions (usually 850 - 1200°C), enabling the reducing agent to chemically react with nitrogen oxides (NOx) in the flue gas to generate nitrogen gas (N2) and water (H2O), thereby achieving the purpose of removing NOx.

[0057] Activated carbon system: A purification treatment system that adsorbs and removes harmful substances (such as heavy metals, dioxins, etc.) in the flue gas by injecting activated carbon.

[0058] Fabric filter: It is a key equipment used in the flue gas treatment system of garbage incineration to remove harmful substances such as dust, heavy metals, dioxins, etc. generated during incineration. It has the advantages of high-efficiency filtration, high temperature resistance, corrosion resistance, etc. The flue gas is filtered through the fabric material to ensure that the flue gas emissions meet environmental protection standards.

[0059] SCR: In waste incineration, SCR (Selective Catalytic Reduction) refers to the selective catalytic reduction technology, which is an efficient flue gas denitrification technology. It uses a catalyst to react nitrogen oxides (NOx) in the flue gas with a reducing agent (such as ammonia) at a relatively low temperature (usually 200°C - 450°C) to produce harmless nitrogen and water, thereby purifying the flue gas and reducing air pollution.

[0060] GGH: GGH (Gas-Gas Heater) is an efficient heat energy recovery device. It uses heat exchange between high-temperature flue gas and low-temperature flue gas to effectively reduce the flue gas emission temperature, while preheating the air entering the boiler or recovering heat energy for other process, thereby improving the energy utilization efficiency of the entire system.

[0061] SGH: SGH refers to the Steam Gas Heater. It is a flue gas reheating system that heats the relatively low-temperature flue gas at the outlet of the bag filter to the temperature range suitable for denitrification by the SCR (Selective Catalytic Reduction) system through direct steam heating. Usually, the operating temperature of the SCR catalyst is 170 - 200°C. SGH plays a key role in the waste incineration flue gas purification process, helping to improve the stability and denitrification efficiency of the SCR system, thereby effectively controlling the nitrogen oxide emissions generated during waste incineration.

[0062] Wet method: It refers to a technology used to purify flue gas during waste incineration. It uses an alkaline solution (such as limestone solution) to chemically react with acidic gases (such as HCl, SO2, etc.) in the flue gas in a scrubbing tower to produce salts and water, thereby removing the acidic components in the flue gas and achieving the purpose of acid removal. The wet method has high acid removal efficiency, but has high requirements for equipment and may produce a large amount of wastewater, requiring the configuration of a wastewater treatment device.

[0063] Condensing heat exchanger: It refers to a device used to recover and utilize the latent heat of vaporization of water vapor in the flue gas during waste incineration. It reduces the flue gas discharge temperature below the saturation temperature, causing the superheated water vapor in the flue gas to condense into liquid water and release the latent heat of vaporization, thereby improving the heat exchange efficiency. The condensing heat exchanger can effectively improve the energy utilization efficiency of the incineration system, reduce heat loss, and also helps to purify the flue gas and reduce pollutant emissions. It is an important part of waste incineration technology.

[0064] Latent heat: It refers to the heat released when water vapor in the flue gas changes from gaseous state to liquid state during the waste incineration process. This heat transformation occurs during the flue gas cooling process. When the temperature drops below the dew point, water vapor condenses into liquid water, and at the same time, a large amount of energy, namely latent heat, is released. The recovery and utilization of latent heat are of great significance for improving the energy efficiency of the waste incineration system and reducing heat loss, and can be achieved through equipment such as condensation heat exchangers.

[0065] Chimney: The chimney of waste incineration refers to the tall structure in the waste incineration equipment used to discharge the exhaust gas generated by combustion. It is an important part of the waste incineration system, and its main function is to discharge the exhaust gas after combustion out of the building.

[0066] SCR sealing air: SCR sealing air refers to an air flow introduced specifically for purging, sealing and protecting during the process of flue gas denitrification using selective catalytic reduction (SCR) technology. In order to ensure that the internal components of the SCR system (such as catalysts) are not eroded by external flue gas and maintain the system's tightness. The sealing air needs to be heated before being sent into the internal components. This sealing air helps prevent flue gas leakage, protects the catalyst from damage, and maintains the normal operation and high-efficiency denitrification of the SCR system.

[0067] SCR dilution air: It refers to a certain amount of hot air blown in by a dilution fan in the selective catalytic reduction (SCR) denitrification process, which is used to dilute ammonia to a certain ratio and then spray it into the reactor pipeline to remove nitrogen oxides in the combustion flue gas, achieving an air flow for environmental protection purposes.

[0068] Ultra-low emissions: Ultra-low emissions of waste incineration flue gas refer to the significant reduction of the emission concentrations of pollutants such as soot, sulfur dioxide, and nitrogen oxides during the waste incineration process by adopting advanced flue gas treatment processes, reaching far lower than the limit values of national emission standards, thus achieving environmental friendliness and sustainable development. Conventional emissions refer to meeting the limit values of national emission standards.

[0069] Example 1

[0070] Such as Figure 1An energy-saving waste incineration flue gas purification device shown in the figure is sequentially provided with an incinerator 1, a waste heat boiler 4, a dust removal device, an SCR device 7, a GGH1 device 8, a GGH2 device 9, a GGH3 device 10, an induced draft fan 11 and a chimney 12 along the waste incineration flue gas traveling route. The incinerator 1 is connected with an air preheater 15 that supplies air to the incinerator 1; it also includes an in-furnace dry method device 2 and an SNCR device 3. The in-furnace dry method device 2 sprays deacidifying agent powder into the furnace chamber of the incinerator 1, and the SNCR device 3 sprays denitrifying agent powder into the flue of the waste heat boiler 4; it also includes a heat exchange component that utilizes the sensible heat and latent heat in the flue gas. The heat exchange component includes a condensation heat exchanger 14. The condensation heat exchanger 14 is provided with an air inlet, an air outlet, a flue gas inlet and a flue gas outlet. The air outlet of the condensation heat exchanger 14 is connected to the GGH1 device 8 through a pipeline. The air outlet of the GGH1 device 8 is connected to the air inlet of the SCR device 7 through a pipeline. The GGH1 device 8 supplies dilution air and sealing air to the SCR device 7.

[0071] The dust removal device includes an activated carbon device 5 and a bag filter 6. The feeding end of the activated carbon device 5 is connected to the discharging end of the waste heat boiler 4. The discharging end of the activated carbon device 5 is connected to the feeding end of the bag filter 6. The discharging end of the bag filter 6 is connected to the feeding end of the SCR device 7.

[0072] This energy-saving waste incineration flue gas purification device also includes a wet scrubber 13. The flue gas inlet of the wet scrubber 13 is connected to the flue gas outlet of the GGH2 device 9. The flue gas outlet of the wet scrubber 13 is connected to the flue gas inlet of the condensation heat exchanger 14. The flue gas outlet of the condensation heat exchanger 14 is connected to the GGH2 device 9 through a pipeline.

[0073] The GGH3 device 10 is provided with an air inlet and an air outlet. The air outlet of the GGH3 device 10 is connected to the air inlet of the air preheater 15 through a pipeline.

[0074] An energy-saving waste incineration flue gas purification process uses the above-mentioned energy-saving waste incineration flue gas purification device. The purification process specifically includes the following steps:

[0075] Step S1: The incinerator 1 uses the 200°C air from the air preheater 15 as the primary air. The flue gas generated by it first undergoes preliminary deacidification through the in-furnace dry method device 2 to reduce the concentration of acidic pollutants.

[0076] Step S2: After preliminary deacidification, it then undergoes preliminary denitrification through the SNCR device 3 in a flue.

[0077] Step S3: After the flue gas after preliminary denitrification passes through the waste heat boiler 4, the temperature is controlled at about 190°C.

[0078] Step S4: The flue gas at the outlet of the waste heat boiler 4 passes through the activated carbon device 5 and the bag filter 6 to remove heavy metals and dust.

[0079] Step S5: The flue gas at the outlet of the bag filter 6 goes to the SCR device 7 for further denitrification. The outlet temperature of the flue gas from the bag filter 6 is 185°C. The SCR device 7 uses the 170°C air from the GGH1 device 8 as dilution air and sealing air.

[0080] Step S6: The flue gas at the outlet of the SCR device 7 enters the GGH1 device 8 to exchange heat with the air from the condensation heat exchanger 14, and the temperature is reduced to 165°C. The GGH1 device 8 simultaneously heats the air from the condensation heat exchanger 14 from 60°C to 170°C, and the heated air goes to the SCR device 7.

[0081] Step S7: The flue gas at the outlet of the GGH1 device 8 enters the GGH2 device 9 to exchange heat with the deacidified clean flue gas from the condensation heat exchanger 14, and the temperature is reduced to 95°C.

[0082] Step S8: The dirty flue gas at the outlet of the GGH2 device 9 enters the wet scrubber 13 for further deacidification. The moisture in the dirty flue gas increases to near the saturation state, and the temperature is reduced to 60 - 65°C.

[0083] Step S9: The clean flue gas at the outlet of the wet scrubber 13 enters the condensation heat exchanger 14 for heat exchange, using the sensible heat and latent heat in the flue gas to heat the incoming air. The air is heated to 60°C and then goes to the GGH1 device 8.

[0084] Step S10: The clean flue gas after the condensation heat exchanger 14 goes to the GGH2 device 9 to exchange heat with the dirty flue gas from the GGH1 device 8, and the temperature rises to 120°C.

[0085] Step S11: The clean flue gas heated by the GGH2 device 9 enters the GGH3 device 10 to exchange heat with the primary air. The temperature of the flue gas drops to 55°C, and the primary air is heated to 115°C. The primary air is heated to 200°C again by the air preheater 15 and then sent to the incinerator 1.

[0086] Step S12: The flue gas after heat exchange in the GGH3 device 10 is drawn away by the induced draft fan 11 and discharged from the chimney 12.

[0087] Air at 20 - 40°C is introduced at the air inlet of the GGH3 device 10, and air at 20 - 40°C is introduced at the air inlet of the condensation heat exchanger 14.

[0088] The temperature of the flue gas at the outlet of the SCR device 7 is 180°C.

[0089] In summary, through multi - stage purification, energy recovery, and efficient heat exchange, the present invention realizes the efficient purification of flue gas and the full utilization of energy. The specific effects include:

[0090] (1) High - efficiency purification: Through multi - stage purification by the dry method device 2, SNCR device 3, activated carbon device 5, bag filter 6, SCR device 7, wet scrubber 13, etc. in the furnace, pollutants such as acidic substances, heavy metals, dust, and nitrogen oxides in the flue gas are effectively removed, and the discharged flue gas meets the environmental protection standards.

[0091] (2) Energy recovery: By using three GGH devices and the condensing heat exchanger 14, the sensible heat and latent heat in the flue gas are fully recovered, reducing energy consumption and improving energy utilization efficiency.

[0092] (3) Energy conservation and environmental protection: The overall process design is reasonable, reducing energy consumption, lowering operating costs, and at the same time reducing pollutant emissions, meeting the requirements of energy conservation and environmental protection.

[0093] (4) Extended equipment life: Through multi - stage purification, the load on key equipment such as SGH in the SCR device is reduced, extending the service life of the equipment and lowering maintenance costs.

[0094] Generally speaking, while ensuring the flue gas purification effect, this device and process achieve efficient recovery and utilization of energy, with significant energy - saving and environmental - protection benefits.

[0095] Finally, it should be noted that: The above embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An energy-saving waste incineration flue gas purification device, characterized in that: An incinerator (1), a waste heat boiler (4), a dust removal device, an SCR device (7), a GGH1 device (8), a GGH2 device (9), a GGH3 device (10), a forced draft fan (11) and a chimney (12) are sequentially arranged along the traveling route of the waste incineration flue gas. The incinerator (1) is connected with an air preheater (15) that supplies air to the incinerator (1). It further includes an in-furnace dry process device (2) and an SNCR device (3). The in-furnace dry process device (2) sprays deacidifying agent powder into the furnace chamber of the incinerator (1), and the SNCR device (3) sprays denitrifying agent powder into the flue of the waste heat boiler (4). It further includes a heat exchange component that utilizes the sensible heat and latent heat in the flue gas. The heat exchange component includes a condensation heat exchanger (14). The condensation heat exchanger (14) is provided with an air inlet, an air outlet, a flue gas inlet and a flue gas outlet. The air outlet of the condensation heat exchanger (14) is connected to the GGH1 device (8) through a pipeline. The air outlet of the GGH1 device (8) is connected to the air inlet of the SCR device (7) through a pipeline. The GGH1 device (8) supplies dilution air and sealing air to the SCR device (7).

2. An energy-saving waste incineration flue gas purification device according to claim 1, characterized in that: The dust removal device includes an activated carbon device (5) and a bag filter (6). The feed end of the activated carbon device (5) is connected to the discharge end of the waste heat boiler (4). The discharge end of the activated carbon device (5) is connected to the feed end of the bag filter (6). The discharge end of the bag filter (6) is connected to the feed end of the SCR device (7).

3. An energy-saving waste incineration flue gas purification device according to claim 1, characterized in that: It further includes a wet scrubber (13). The flue gas inlet of the wet scrubber (13) is connected to the flue gas outlet of the GGH2 device (9). The flue gas outlet of the wet scrubber (13) is connected to the flue gas inlet of the condensation heat exchanger (14). The flue gas outlet of the condensation heat exchanger (14) is connected to the GGH2 device (9) through a pipeline.

4. An energy-saving waste incineration flue gas purification device according to claim 1, characterized in that: The GGH3 device (10) is provided with an air inlet and an air outlet. The air outlet of the GGH3 device (10) is connected to the air inlet of the air preheater (15) through a pipeline.

5. A purification process for energy-saving waste incineration flue gas, characterized in that: The purification process uses an energy-saving waste incineration flue gas purification device as described in any one of claims 1 to 4. The purification process specifically includes the following steps: Step S1: The incinerator (1) uses 200°C air from the air preheater (15) as the primary air. The flue gas generated by it is first preliminarily deacidified by the in-furnace dry process device (2) to reduce the concentration of acidic pollutants. Step S2: After preliminary deacidification, it is then preliminarily denitrified by the SNCR device (3) in a flue. Step S3: After the flue gas after preliminary denitrification passes through the waste heat boiler (4), the temperature is controlled at about 190°C. Step S4: The flue gas at the outlet of the waste heat boiler (4) passes through the activated carbon device (5) and the bag filter (6) to remove heavy metals and dust. Step S5: The flue gas at the outlet of the bag filter (6) goes to the SCR device (7) for further denitrification. The outlet temperature of the flue gas of the bag filter (6) is 185°C. The SCR device (7) uses 170°C air from the GGH1 device (8) as dilution air and sealing air. Step S6: The flue gas at the outlet of the SCR device (7) enters the GGH1 device (8) to exchange heat with the air from the condensation heat exchanger (14), and the temperature is reduced to 165 °C. At the same time, the GGH1 device (8) heats the air from the condensation heat exchanger (14) from 60 °C to 170 °C, and the heated air goes to the SCR device (7). Step S7: The flue gas at the outlet of the GGH1 device (8) enters the GGH2 device (9) to exchange heat with the deacidified clean flue gas from the condensation heat exchanger (14), and the temperature is reduced to 95 °C. Step S8: The dirty flue gas at the outlet of the GGH2 device (9) enters the wet scrubber (13) for further deacidification. The moisture in the dirty flue gas increases to near the saturation state, and the temperature is reduced to 60 - 65 °C. Step S9: The clean flue gas at the outlet of the wet scrubber (13) enters the condensation heat exchanger (14) for heat exchange. The sensible heat and latent heat in the flue gas are used to heat the incoming air. After the air is heated to 60 °C, it goes to the GGH1 device (8). Step S10: The clean flue gas after the condensation heat exchanger (14) goes to the GGH2 device (9) to exchange heat with the dirty flue gas from the GGH1 device (8), and the temperature rises to 120 °C. Step S11: The clean flue gas heated by the GGH2 device (9) enters the GGH3 device (10) to exchange heat with the primary air. The temperature of the flue gas is reduced to 55 °C, and the primary air is heated to 115 °C. The primary air is further heated to 200 °C by the air preheater (15) and then sent to the incinerator (1). Step S12: The flue gas after heat exchange in the GGH3 device (10) is drawn away by the induced draft fan (11) and discharged from the chimney (12).

6. The purification process of energy-saving waste incineration flue gas according to claim 5, characterized in that: Air at 20 - 40 °C is introduced at the air inlet of the GGH3 device (10).

7. A purification process for energy-saving waste incineration flue gas according to claim 5, characterized in that: Air at 20 - 40 °C is introduced at the air inlet of the condensation heat exchanger (14).

8. The purification process of energy-saving waste incineration flue gas according to claim 5, characterized in that: The temperature of the flue gas at the outlet of the SCR device (7) is 180 °C.

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