Waste incineration flue gas treatment device

Abstract

The utility model discloses a waste incineration flue gas treatment device which comprises a waste incinerator, a waste heat boiler, a baking soda dry deacidification flue, an SCR denitration bag type dust collector, a waste heat utilization device, an induced draft fan and a chimney which are sequentially arranged in the flowing direction of flue gas. An SNCR system is arranged on the garbage incinerator, an ejector of the SNCR system sprays a denitration agent into the garbage incinerator, and the denitration agent reacts with NOx to be reduced into N2; the system is provided with a storage, preparation and injection system of baking soda dry powder and is used for injecting baking soda powder into the dry-process deacidification flue to absorb acid gas in flue gas; the SCR denitration bag type dust collector comprises a dust collector body and an SCR denitration filter bag arranged in the dust collector body; the outermost layer of the SCR denitration filter bag is an expanded polytetrafluoroethylene film, and the inner layer of the SCR denitration filter bag is a composite catalytic felt loaded with a catalyst. The flue gas temperature is fully utilized, additional heating is not needed, and operation energy consumption is remarkably reduced. And the method is suitable for waste incineration flue gas treatment.

Description

TECHNICAL FIELD

[0001] The utility model belongs to environmental protection technical field relates to a kind of waste incineration flue gas treatment device. BACKGROUND

[0002] As a kind of efficient waste disposal, waste incineration for power generation plays an important role in reducing waste volume and recycling energy. However, the flue gas generated during waste incineration contains various pollutants, including acid gases (such as sulfur dioxide, hydrogen chloride), nitrogen oxides (NOx), dioxins, and heavy metals, etc. If not effectively controlled, it will cause serious pollution to the atmospheric environment, threatening human health and ecological safety. Therefore, the research and application of waste incineration flue gas treatment technology have become an important issue in the field of environmental protection.

[0003] In recent years, the scale of waste incineration for power generation industry in China has been expanding, and the problem of flue gas emission has gradually become prominent, attracting widespread attention from all sectors of society. To cope with the increasingly severe environmental pressure, the national and local governments have continuously improved the requirements for waste incineration flue gas emission standards. The "Domestic Waste Incineration Pollution Control Standard" (GB 18485-2014) published in 2014 stipulates that the 24-hour average emission limit of sulfur dioxide (SO2) is 80 mg / m 3 , and the 24-hour average emission limit of nitrogen oxides (NOx) is 250 mg / m 3 . However, with the enhancement of environmental awareness and the progress of technology, some regions have begun to develop and implement more stringent local emission standards. For example, the local standard issued by a certain province and city significantly reduces the 24-hour average emission limit of sulfur dioxide from 80 mg / m 3 to 20 mg / m 3 , and the 24-hour average emission limit of nitrogen oxides from 250 mg / m 3 to 80 mg / m 3 . At the same time, it adds control requirements for ammonia (NH3) emission, requiring its concentration not to exceed 8 mg / m 3 . The implementation of these standards poses higher challenges to the flue gas treatment technology of waste incineration for power generation enterprises.

[0004] Currently, the flue gas treatment process widely used in domestic waste incineration power plants is "SNCR in-furnace denitration + (rotary atomizer semi-dry method + dry method) acid removal (calcium-based) + activated carbon injection + bag filter". This process uses SNCR (selective non-catalytic reduction) technology to inject a denitration agent (such as ammonia water or urea) in the furnace to partially remove part of the NOx, uses a combination of semi-dry and dry methods to remove acid gases, uses activated carbon to adsorb dioxins and heavy metals, and finally removes particulate matter through a bag filter. However, this process has obvious shortcomings when faced with new landmark requirements. First, the SNCR denitration efficiency is limited, usually only removing 30%-50% of NOx, which cannot meet the requirement of reducing nitrogen oxide emissions to 80 mg / m 3 . Second, the semi-dry and dry acid removal efficiency of sulfur dioxide is limited by reaction conditions and the utilization rate of the acid removal agent, making it difficult to stably reach the emission limit of 20 mg / m 3 . In addition, the process has weak control over ammonia escape, making it difficult to meet the requirements of local standards for ammonia emissions.

[0005] The flue gas treatment process widely used in newly built waste incineration power plants is "SNCR in-furnace denitration + semi-dry acid removal + wet acid removal + activated carbon injection + bag filter + SCR denitration". However, this flue gas treatment process has many problems:

[0006] First, the addition of wet tower and wastewater treatment system, flue gas reheating system, and SCR reaction tower and other equipment significantly increases investment costs, usually by tens of millions of yuan;

[0007] Second, the operating costs are high, the SCR system consumes a large amount of catalyst and reducing agent, and the flue gas is first cooled in the acid removal link and then heated in the flue gas reheating system to meet the required flue gas temperature, resulting in significant increase in energy consumption;

[0008] Third, the flue gas resistance increases due to the addition of equipment, requiring higher performance of the induced draft fan, resulting in a significant increase in induced draft fan energy consumption;

[0009] Fourth, the addition of equipment occupies a large area, which is not conducive to sites with limited space;

[0010] These problems make the traditional flue gas treatment process face technical and economic challenges in practical application.

[0011] In view of the above problems, it is urgent to develop a high-efficiency, low-cost, and small-area flue gas treatment technology to meet strict emission standards while reducing investment and operating costs, improving the overall economic efficiency and environmental benefits of the system. Practical new type content

[0012] Therefore, the garbage incineration flue gas treatment device is provided to overcome the defects of the prior art, and the device can realize the synergistic and efficient removal of pollutants such as acid gases, nitrogen oxides, dioxins and heavy metals, and can reduce the transformation cost, operation energy consumption and occupied area, and meet increasingly strict emission standards.

[0013] To achieve the above object, the utility model provides the following technical scheme:

[0014] A garbage incineration flue gas treatment device comprises a garbage incinerator, a waste heat boiler, an SCR denitration bag-type dust collector, an induced draft fan and a chimney which are sequentially arranged along the flue gas flow direction.

[0015] An SNCR system is arranged on the garbage incinerator, and an injector of the SNCR system sprays a denitration agent solution into the garbage incinerator to react with NOx and be reduced into N2.

[0016] The waste heat boiler is connected with the SCR denitration bag-type dust collector through a baking soda dry method deacidification flue; a storage, preparation and injection system of baking soda dry powder is arranged near the inlet end of the baking soda dry method deacidification flue, and an activated carbon injection system and an SCR reducing agent evaporation system are arranged near the outlet end of the baking soda dry method deacidification flue; the storage, preparation and injection system of baking soda dry powder is used for spraying baking soda powder into the baking soda dry method deacidification flue to absorb acid gases in the flue gas; the activated carbon injection system is used for spraying activated carbon to adsorb dioxins and heavy metals; and the SCR reducing agent evaporation system is used for providing reducing agents for the SCR denitration reaction.

[0017] Further, the SCR denitration bag-type dust collector comprises a dust collector body and an SCR denitration filter bag arranged in the dust collector body; the outermost layer of the SCR denitration filter bag is an expanded polytetrafluoroethylene film, and the inner layer is a composite catalyst felt loaded with a catalyst.

[0018] Further, a waste heat utilization device is arranged on the connecting pipeline between the SCR denitration bag-type dust collector and the induced draft fan, the waste heat utilization device absorbs flue gas heat through a heat exchanger and is connected with a steam turbine to heat the steam turbine condensate water.

[0019] Further, the storage, preparation and injection system of baking soda dry powder comprises sequentially connected baking soda storage bins, a baking soda metering module, a grinding machine, a conveying fan and a spray gun; after the baking soda coarse powder is metered, the baking soda coarse powder is ground into fine powder with a fineness D90≤20 μm through the grinding machine, and then the fine powder is sprayed into the baking soda dry method deacidification flue through the conveying fan and the spray gun.

[0020] Further, the inlet end of the baking soda dry method deacidification flue is provided with sensors for detecting the concentrations of SO2 and HCl; the sensors are connected with the storage, preparation and injection system of baking soda dry powder to adjust the amount of baking soda supplied into the flue gas.

[0021] Further, the SCR reductant evaporation system comprises a reductant delivery module, a metering module, a dilution air system and an ammonia injection grid, the ammonia injection grid is arranged on the baking soda dry deacidification flue, and the reductant is delivered to the ammonia injection grid through pyrolysis gasification and the reductant delivery module.

[0022] The beneficial effects of the utility model lie in:

[0023] 1. Efficiently synergistically treating pollutants: the utility model realizes efficient removal of acid gases and NOx by the efficient synergy of the baking soda dry deacidification technology and the SCR denitration bag-type dust collector in the temperature range of 190-240 DEG C, and ensures that the flue gas emission fully meets the local most stringent standard. 2. Reducing investment cost and land area: compared with the traditional flue gas treatment process, the utility model adopts baking soda dry deacidification instead of semi-dry + wet deacidification, and the semi-dry deacidification tower, the wet deacidification tower and the wet deacidification wastewater treatment system are omitted, meanwhile, the SCR denitration and the bag-type dust collector are integrated in the same equipment, and the independent SCR reactor and the flue gas reheating system are omitted, so that the number of equipment and the land area are reduced, the reconstruction investment cost is reduced by about 30%-40%, and the utility model is particularly suitable for the construction site with limited space. 3. Reducing operation energy consumption: the utility model fully utilizes the temperature of 190-240 DEG C of the waste incineration flue gas, does not need additional flue gas heating device, and the baking soda dry deacidification and the SCR denitration are efficiently operated in the temperature range, so that the energy consumption is significantly reduced; meanwhile, the waste heat utilization device recovers the flue gas heat for heating the condensed water, further improves the energy utilization efficiency, and reduces the operation cost.

[0029] 4. Stable and reliable operation and simple maintenance: the SCR denitration filter bag adopts the structure of expanded polytetrafluoroethylene film and composite catalyst felt, the catalyst is located downstream of the filter layer, dust blockage and wear are avoided, the operation life reaches 5 years, and regeneration is not needed (the traditional catalyst needs to be regenerated once every 3 years). The utility model has no catalyst poisoning and blockage risk, the system operation is stable, and the maintenance workload is less than that of the traditional scheme. 5. Environment-friendly and economic: the by-product of the baking soda dry deacidification is solid salt, which is convenient to collect and treat, and the operation of the baking soda dry deacidification system can effectively reduce the generation amount of fly ash. The waste water problem caused by the wet deacidification is avoided; the system is stable in overall operation, the maintenance cost is low, and good economic benefit and environmental benefit are obtained.

[0028] The other advantages, objects, and features of the present application will become more apparent in light of the following detailed description of the best mode contemplated for carrying out the application. It is intended that all such additional advantages and features be included within the scope of the present application, and embraced by the appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to make the objectives, technical solutions and advantages of the present application clearer, the following will make a preferred detailed description of the present application in combination with the drawings, in which:

[0030] Figure 1 The figure is a device layout diagram of the garbage incineration flue gas treatment device in the present application.

[0031] Reference signs: 1-garbage incinerator; 2-waste heat boiler; 3-soda dry deacidification flue; 4-SCR denitration bag-type dust collector; 5-waste heat utilization device; 6-induced draft fan; 7-chimney; 8-SNCR system; 9-activated carbon injection system; 10-SCR reducing agent evaporation system; 11-storage, preparation and injection system of soda dry powder. DETAILED DESCRIPTION

[0032] The embodiments of the present application will be described in detail with specific examples. Those skilled in the art can easily understand other advantages and functions of the present application from the content disclosed in the specification. The present application can also be implemented or applied in different specific embodiments, and each detail in the specification can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be noted that the drawings provided in the following examples only illustrate the basic concept of the present application in a schematic manner, and the following examples and features in the examples can be combined with each other without conflict.

[0033] It should be noted that the drawings are only used for illustrative explanation, and the representation is only a schematic diagram, not a physical diagram, and cannot be understood as a limitation of the present application; in order to better illustrate the embodiments of the present application, some components in the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some known structures and their descriptions in the drawings may be omitted.

[0034] The same or similar reference signs in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it should be understood that, if the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "front", "back" and the like are based on the orientations or positional relationships shown in the drawings, they are only for the convenience of describing the present application and simplifying the description, and thus the terms describing the positional relationships in the drawings do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed in a specific orientation and be operated, therefore, the terms describing the positional relationships in the drawings are only used for exemplary illustration, and cannot be understood as a limitation on the present application, and for those skilled in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0035] Please refer to Figure 1 It is a kind of garbage incineration flue gas treatment device, including the garbage incineration furnace 1, waste heat boiler 2, baking soda dry method deacidification flue 3, SCR denitration bag type dust collector 4, waste heat utilization device 5, induced draft fan 6, chimney 7 in sequence along the flue gas flow direction;

[0036] SNCR system 8 is arranged on the garbage incineration furnace 1, and the denitration agent solution including but not limited to ammonia water or urea is sprayed into the garbage incineration furnace 1 by injector, and is reacted with NOx To reduce N2;

[0037] Waste heat boiler 2 is connected between SCR denitration bag type dust collector 4 and baking soda dry method deacidification flue 3;Small soda dry powder storage, preparation and injection system 11 is arranged near the inlet end of baking soda dry method deacidification flue 3, active carbon injection system 9 and SCR reducing agent evaporation system 10 are arranged near the outlet end of baking soda dry method deacidification flue 3;Small soda dry powder storage, preparation and injection system 11 is used to spray small soda powder into baking soda dry method deacidification flue 3 to absorb acid gas in flue gas;Active carbon injection system 9 is used to spray active carbon to adsorb dioxin and heavy metal;SCR reducing agent evaporation system 10 is used to provide reducing agent for SCR denitration reaction.

[0038] The inlet end of baking soda dry method deacidification flue 3 is also provided with a sensor for detecting the concentration of SO2 and HCl, and the sensor is connected with the small soda dry powder storage, preparation and injection system, for adjusting the amount of baking soda supplied to the flue gas.

[0039] SCR reducing agent evaporation system 10 includes reducing agent conveying module, metering module, dilution air system and ammonia injection grid, ammonia injection grid is arranged on baking soda dry method deacidification flue 3, and reducing agent is conveyed to ammonia injection grid after pyrolysis gasification through reducing agent conveying module.

[0040] The SCR denitration bag-type dust collector 4 is connected to the baking soda dry method deacidification flue 3, and is used for removing particulate matters and NOx in the flue gas. The baking soda dry method deacidification flue 2 is provided with sensors for detecting the concentrations of SO2 and HCl at the inlet, and the sensors are connected to a baking soda dry powder storage, preparation and injection system 11, and are used for adjusting the amount of baking soda supplied to the flue gas.

[0041] The waste heat utilization device 5 adopts a heat exchanger, which is installed on the flue gas pipeline at the outlet of the SCR denitration bag-type dust collector 4, recovers the heat of the flue gas, and uses the heat to heat the steam turbine condensate water.

[0042] Example 1: 500t / d incineration line normal operation condition

[0043] In this embodiment, a newly-built 500t / d garbage incineration power generation project is provided with the treatment device of the utility model. The process flow is: SNCR in-furnace denitration→baking soda dry method deacidification→activated carbon injection→SCR denitration bag-type dust collector→waste heat utilization. The specific implementation steps are as follows:

[0044] 1. SNCR in-furnace denitration

[0045] The SNCR system 8 is arranged on the garbage incinerator 1, ammonia water / urea solution is used as the denitration reducing agent, is sprayed into the furnace (temperature 850-1150℃) through the SNCR injector, reacts with NOx in the flue gas to generate N2 and water vapor, and the preliminary denitration efficiency reaches 40%. The flue gas amount of the incineration line under the standard condition is 89580Nm 3 / h, and the flue gas temperature is 200℃.

[0046] 2. Baking soda dry method deacidification

[0047] The baking soda dry powder storage, preparation and injection system 11 is arranged. The baking soda coarse powder (D50=200μm) is metered through the baking soda storage bin (effective volume 3m 3 ), is ground to a fineness D90≤20μm through the grinding machine, and the output of the grinding machine is 167kg / h. The fine powder is sprayed into the baking soda dry method deacidification flue (the flue length meets the 2s deacidification time) through the Roots blower and the spray gun, reacts with the acid gases (SO2, HCl, etc.) in the flue gas, and the deacidification efficiency reaches 97%. The baking soda amount is 8.14kg / t of garbage, and the flue gas temperature is kept at 200℃.

[0048] 3. Activated carbon injection

[0049] The activated carbon injection system 9 is used for spraying activated carbon into the flue gas pipeline at the inlet of the SCR denitration bag-type dust collector 4, the spraying amount is 0.43kg / t of garbage, the activated carbon absorbs dioxin and heavy metals in the flue gas, and the dioxin removal rate reaches 99%.

[0050] 4. SCR denitration bag-type dust collector

[0051] SCR denitration bag type dust collector is configured with 967 SCR denitration filter bags (specifications Φ160x6000mm), filter bag area is 2900m 2 , and filter wind speed is 0.89m / min. The SCR reducing agent evaporation system 10 is used for preparing and spraying ammonia into a flue gas pipeline at an inlet of the SCR denitration bag type dust collector 4, and includes a reducing agent conveying module (a used reducing agent solution storage tank), a metering module, a dilution air system (air volume is 2500m 3 / h, pressure is 4200Pa) and an ammonia spraying grid. The reducing agent is mixed with hot air generated by a heater to generate ammonia by pyrolysis, ammonia concentration is controlled to be below 5%, and the ammonia is sprayed into a flue through the ammonia spraying grid. NOx in the flue gas reacts with the ammonia under the catalysis of the SCR denitration filter bag, denitration efficiency reaches 90%, and particulate matter capture efficiency is >99.99%.

[0052] 5, waste heat utilization

[0053] A heat exchanger is installed on a flue at an outlet of the SCR denitration bag type dust collector, flue gas inlet temperature is 190℃, outlet temperature is reduced to 140℃, and the heat-absorbing working medium is low-pressure heater outlet condensate water (80℃), which is heated and returned to a deaerator (110℃), and the recovered heat is converted into steam at a rate of 2.51t / h.

[0054] Operation results:

[0055] After detection, the emission indexes of the treated flue gas are as follows: SO2 concentration is 5mg / Nm 3 , NOx concentration is 70mg / Nm 3 , particulate matter concentration is 10mg / Nm 3 , ammonia escape concentration is 8mg / Nm 3 , and dioxin removal rate is 99%. When running for 8000 hours per year, fly ash amount is 11.89t / d, operation cost per ton of garbage is 55.43 yuan, total investment is 9.46 million yuan, and annual operation cost saving is 5.15 million yuan (compared with a traditional SCR scheme).

[0056] Embodiment 2: 500t / d incineration line high-load operation condition

[0057] In this embodiment, the same 500t / d incineration line is used to verify the adaptability of the treatment device in the utility model under the condition of high flue gas volume and high pollutant concentration. The process flow is the same as that in embodiment 1, and the specific implementation steps are as follows:

[0058] 1, SNCR in-furnace denitration

[0059] The efficiency of denitration is still 40% by using ammonia / urea solution as a reducing agent, which is injected into the waste incinerator 1 through the SNCR injector to react with NOx. The flue gas volume is 98538 Nm 3 / h, and the flue gas temperature is raised to 220℃.

[0060] 2. Baking soda dry method

[0061] The storage, preparation and injection system 11 of the baking soda dry powder are regulated. The baking soda coarse powder is ground to D90≤20μm by a grinder, and the injection amount is adjusted to 9.2kg / t of garbage to deal with higher SO2 concentration. At a flue gas temperature of 220℃, the deacidification efficiency is more than 97%, and SO2 is removed to 10mg / Nm 3 / h.

[0062] 3. Activated carbon injection

[0063] The injection amount of activated carbon is 0.5kg / t of garbage, which effectively adsorbs dioxin and heavy metals, and the removal rate of dioxin is maintained at 99%.

[0064] 4. SCR denitration bag type dust removal

[0065] The same 967 SCR denitration filter bags (filter bag area 2900m 2 , filtration wind speed 0.98m / min) are used. The operating parameters of the SCR reducing agent evaporation system 10 remain unchanged, the urea solution is pyrolyzed to generate ammonia, and the ammonia injection grid accurately controls the ammonia injection amount to ensure that the NOx removal efficiency is ≥90%. Due to the high initial NOx concentration, the final emission concentration is controlled within 70mg / Nm 3 , and the particulate matter concentration is still lower than 10mg / Nm 3 .

[0066] 5. Waste heat utilization

[0067] The operating parameters of the heat exchanger are adjusted, the flue gas inlet temperature is 210℃, the outlet temperature is reduced to 160℃, the condensate water is heated from 80℃ to 110℃, and the recovered heat is converted into steam at a rate of 2.51t / h.

[0068] Operation results:

[0069] After detection, the emission indicators of the treated flue gas are: SO2 concentration is 10mg / Nm 3 , NOx concentration is 70mg / Nm 3 , particulate matter concentration is 8mg / Nm 3 , and ammonia escape concentration is 8mg / Nm 3The dioxin removal rate is 99%. The fly ash amount is 12.21 t / d, and the operation cost of per ton of garbage is about 58.46 yuan per year, which is still lower than 86.35 yuan of the traditional SCR scheme. The system runs stably, and no catalyst blockage or poisoning phenomenon occurs.

[0070] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the purpose and scope of the present application, and all should be covered in the scope of the claims of the present application.

Claims

1. A waste incineration flue gas treatment device, characterized by: The waste incinerator comprises a waste incinerator, a waste heat boiler, an SCR denitration bag-type dust collector, an induced draft fan and a chimney which are sequentially arranged along the direction of the flue gas flow. The waste incinerator is provided with an SNCR system, and an injector of the SNCR system sprays a denitration agent solution into the waste incinerator to react with NOx and be reduced into N2. The waste heat boiler is connected with the SCR denitration bag-type dust collector through a baking soda dry method deacidification flue, a storage, preparation and injection system of baking soda dry powder is arranged near the inlet end of the baking soda dry method deacidification flue, an activated carbon injection system and an SCR reducing agent evaporation system are arranged near the outlet end of the baking soda dry method deacidification flue, the storage, preparation and injection system of baking soda dry powder is used for spraying baking soda powder into the baking soda dry method deacidification flue to absorb acidic gases in the flue gas, the activated carbon injection system is used for spraying activated carbon to adsorb dioxins and heavy metals, and the SCR reducing agent evaporation system is used for providing reducing agents for the SCR denitration reaction.

2. The waste incineration flue gas treatment device according to claim 1, characterized in that: The SCR denitration bag-type dust collector comprises a dust collector body and an SCR denitration filter bag arranged in the dust collector body, the outermost layer of the SCR denitration filter bag is an expanded polytetrafluoroethylene film, and the inner layer is a composite catalyst felt loaded with a catalyst.

3. The waste incineration flue gas treatment device according to claim 1, characterized in that: A waste heat utilization device is arranged on the connecting pipeline between the SCR denitration bag-type dust collector and the induced draft fan, the waste heat utilization device absorbs heat of the flue gas through a heat exchanger and is connected with a steam turbine to heat condensate water of the steam turbine.

4. The waste incineration flue gas treatment device according to claim 1, characterized in that: The storage, preparation and injection system of baking soda dry powder comprises sequentially connected baking soda storage bins, a baking soda metering module, a grinding machine, a conveying fan and a spray gun, baking soda coarse powder is ground into fine powder with a fineness D90 of 20 μm through the grinding machine after metering, and the fine powder is sprayed into the baking soda dry method deacidification flue through the conveying fan and the spray gun.

5. The waste incineration flue gas treatment device according to claim 4, characterized in that: The inlet end of the baking soda dry method deacidification flue is provided with sensors for detecting the concentrations of SO2 and HCl, the sensors are connected with the storage, preparation and injection system of baking soda dry powder, and are used for adjusting the amount of baking soda supplied into the flue gas.

6. The waste incineration flue gas treatment device according to claim 1, characterized in that: The SCR reducing agent evaporation system comprises a reducing agent conveying module, a metering module, a dilution air system and an ammonia injection grid, the ammonia injection grid is arranged on the baking soda dry method deacidification flue, and the reducing agent is conveyed to the ammonia injection grid through the reducing agent conveying module after pyrolysis and gasification.

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