Waste incineration flue gas treatment system

Abstract

The utility model discloses a waste incineration flue gas treatment system which comprises a waste incinerator, a waste heat boiler, a baking soda dry deacidification tower, 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 flue gas flowing direction. 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 dry-process deacidification tower 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 tower 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 waste incineration flue gas treatment device is convenient to transform and 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 system. 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 (NO x ), 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 emerged, 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 + dry) deacidification (calcium-based) + activated carbon injection + bag filter". This process removes part of NOx by injecting a denitrification agent (such as ammonia water or urea) into the furnace using SNCR (selective non-catalytic reduction) technology, removes acid gases using a combination of semi-dry and dry methods, uses activated carbon to adsorb dioxins and heavy metals, and finally removes particulate matter using 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 oxides emissions to 80 mg / m 3 . Second, the semi-dry and dry deacidification efficiency for sulfur dioxide removal is limited by reaction conditions and the utilization rate of deacidification agents, making it difficult to stably achieve an 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] To cope with more stringent emission standards, many waste incineration power plants have begun to upgrade the existing flue gas treatment system. The commonly used modification scheme is to add an SCR (selective catalytic reduction) denitration device based on the previous process, which uses catalysts to efficiently remove NOx at lower temperatures, and optimizes the deacidification process to meet the emission requirements of sulfur dioxide and ammonia.

[0006] However, this modification scheme has many problems:

[0007] First, the modification engineering quantity is large, and new SCR reactors, flue gas reheating systems, and other equipment need to be added, resulting in a significant increase in investment costs, usually up to tens of millions of yuan;

[0008] Second, the operating cost is high, the SCR system needs to consume a large amount of catalyst and reducing agent, and the flue gas heating process requires additional heating energy, resulting in a significant increase in energy consumption;

[0009] Third, the flue gas resistance increases due to the addition of new equipment, which increases the performance requirements of the induced draft fan, and may require replacement or upgrading of the existing fan;

[0010] Fourth, the new equipment occupies a larger space, which is particularly disadvantageous for old power plants with limited space;

[0011] Fifth, the modification requires a long time of furnace shutdown, which seriously affects the normal production and economic benefits of the power plant.

[0012] These problems make the traditional upgrading modification scheme face technical and economic challenges in practical application.

[0013] In view of the above problems, it is urgent to develop an efficient, low-cost, small footprint flue gas treatment technology to meet the strict emission standards while reducing the cost of transformation and operation, and improving the overall economy and environmental benefits of the system. Practical new type content

[0014] Therefore, the garbage incineration flue gas treatment system is provided to overcome the deficiencies of the prior art, achieve the synergistic and efficient removal of pollutants such as acid gases, nitrogen oxides, dioxins and heavy metals, reduce the transformation cost, operation energy consumption and land occupation, and meet the increasingly stringent emission standards.

[0015] To achieve the above object, the utility model provides the following technical scheme:

[0016] A garbage incineration flue gas treatment system comprises a garbage incinerator, a waste heat boiler, a baking soda dry method acid removal tower, an SCR denitration bag-type dust collector, an induced draft fan and a chimney arranged in sequence along the flue gas flow direction.

[0017] The garbage incinerator is provided with an SNCR system, 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.

[0018] The baking soda dry method acid removal tower is provided with a storage, preparation and injection system of baking soda dry powder for spraying baking soda powder into the baking soda dry method acid removal tower to absorb acid gases in the flue gas.

[0019] The SCR denitration bag-type dust collector comprises a dust collector body and an SCR denitration filter bag arranged in the dust collector body.

[0020] Further, an activated carbon injection system and an SCR reducing agent evaporation system are arranged on the connecting pipeline between the baking soda dry method acid removal tower and the SCR denitration bag-type dust collector.

[0021] 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.

[0022] Further, the storage, preparation and injection system of baking soda dry powder comprises a baking soda storage bin, a baking soda metering module, a grinder, a conveying fan and a spray gun connected in sequence.

[0023] Further, the inlet of the baking soda dry deacidification tower is provided with sensors for detecting the concentrations of SO2 and HCl, and the sensors are connected with the storage, preparation and injection system of the baking soda dry powder, for adjusting the amount of baking soda supplied to the flue gas.

[0024] Further, the SCR reducing agent evaporation system comprises a reducing agent delivery module, a metering module, a dilution air system and an ammonia injection grid, the ammonia injection grid is arranged on the flue gas pipeline at the outlet of the baking soda dry deacidification tower, and the reducing agent is delivered to the ammonia injection grid through the pyrolysis gasification and the reducing agent delivery module.

[0025] The beneficial effects of the utility model lie in:

[0026] 1. Efficiently cooperatively treating pollutants: the utility model realizes efficient removal of acid gas and NOx by the efficient cooperation 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.

[0027] 2. Reducing the transformation cost and the occupied area: compared with the traditional flue gas treatment process, the utility model integrates the SCR denitration and the bag-type dust collection in the same equipment, eliminates the independent SCR reactor, fully utilizes the high deacidification efficiency of the baking soda dry deacidification in the temperature range of 190-240 DEG C, eliminates the flue gas reheating system, reduces the equipment quantity and the occupied area, reduces the transformation investment cost by about 30%-40%, and is particularly suitable for the old power plant with limited space.

[0028] 3. Reducing the 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 makes the baking soda dry deacidification and the SCR denitration efficiently operate in the temperature range, so that the energy consumption is obviously 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 expanded polytetrafluoroethylene film and the composite catalyst felt structure, the catalyst is located downstream of the filter layer, avoids dust blockage and abrasion, and has a service life of 5 years and does not need regeneration (the traditional catalyst needs regeneration once every 3 years). The utility model has no catalyst poisoning and blockage risk, the system operates stably, and the maintenance workload is less than that of the traditional scheme.

[0030] 5. Shortening the shutdown time: due to the high process integration degree, the large-scale disassembly is not needed in the transformation process, only part of the equipment needs to be replaced or upgraded, the shutdown time is shortened by more than 50% compared with the traditional scheme, and the influence on the power plant production is reduced.

[0031] 6. Environmental friendliness and economic efficiency: The by-product of the soda dry method deacidification is solid salt, which is easy to collect and handle. The operation of the soda dry method deacidification system can effectively reduce the amount of fly ash. The system is stable in overall operation, low in maintenance cost, and has good economic and environmental benefits.

[0032] Other advantages, objects, and features of the present application will be apparent to those skilled in the art from the following description, and it is intended that the present application be not limited to the embodiments disclosed. The advantages and objects of the present application will be realized and attained by means of the elements and combinations particularly pointed out in the following description. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to make the purpose, technical scheme and advantages of the present application clearer, the following will make a preferred detailed description of the present application combined with the drawings, in which:

[0034] Figure 1 The figure is a device layout diagram of the garbage incineration flue gas treatment system in the present application.

[0035] Reference signs: 1-garbage incinerator; 2-waste heat boiler; 3-soda dry method deacidification tower; 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

[0036] The embodiments of the present application are described below through specific examples. Those skilled in the art can easily understand other advantages and effects of the present application from the disclosure of the present specification. The present application can also be implemented or applied through different specific embodiments, and each detail in the present specification can be modified or changed based on different viewpoints 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.

[0037] 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.

[0038] 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 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, for those skilled in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0039] Please refer to Figure 1 It is a kind of garbage incineration flue gas treatment system, including the garbage incineration furnace 1, waste heat boiler 2, baking soda dry method deacidification tower 3, SCR denitration bag filter 4, waste heat utilization device 5, induced draft fan 6, chimney 7 being sequentially arranged along the flue gas flow direction;

[0040] 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;

[0041] The storage, preparation and injection system 11 of baking soda dry powder is used to spray the prepared baking soda powder into the baking soda dry method deacidification tower 3 to absorb the acid gas in the flue gas.

[0042] The inlet of the baking soda dry method deacidification tower 3 is provided with a sensor for detecting the concentration of SO2 and HCl, and the sensor is connected with the storage, preparation and injection system 11 of baking soda dry powder, for adjusting the amount of baking soda supplied into the flue gas.

[0043] Active carbon injection system 9 is connected to the flue gas pipeline at the outlet of the baking soda dry method deacidification tower 3, for spraying active carbon to adsorb dioxin, heavy metal and other harmful substances.

[0044] SCR reducing agent evaporation system 10 is connected to the flue gas pipeline at the inlet of the SCR denitration bag filter 4, for providing reducing agent for the SCR denitration reaction. The SCR reducing agent evaporation system 10 includes a reducing agent delivery module, a metering module, a dilution air system and an ammonia injection grid, the ammonia injection grid is arranged on the flue gas pipeline at the inlet of the SCR denitration bag filter 4, and the reducing agent is delivered to the ammonia injection grid after pyrolysis and gasification through the reducing agent delivery module.

[0045] The SCR denitration bag-type dust collector 4 is connected to the baking soda dry method acid removal tower 3 through a flue gas pipeline and is used for removing particulate matters and NOx in the flue gas. The baking soda dry method acid removal tower 3 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 for adjusting the amount of baking soda supplied to the flue gas.

[0046] The waste heat utilization device 5 adopts a heat exchanger installed on the flue gas pipeline at the outlet of the SCR denitration bag-type dust collector 4 to recover the heat of the flue gas and use the heat to heat the steam turbine condensate water.

[0047] Example 1: 500t / d incineration line normal operation condition

[0048] In this embodiment, a 500t / d incineration line in a waste incineration power generation project is subjected to flue gas upgrading reconstruction so as to use the treatment system of the present application. The process flow is: SNCR in-furnace denitration→ baking soda dry method acid removal→ activated carbon injection→ SCR denitration bag-type dust collector→ waste heat utilization. The specific implementation steps are as follows:

[0049] 1. SNCR in-furnace denitration

[0050] The SNCR system 8 is installed on the waste incinerator 1, and ammonia water / urea solution is used as the denitration reducing agent, which is sprayed into the furnace (temperature 850-1150℃) through the SNCR injector to react with NOx in the flue gas to generate N2 and water vapor, and the preliminary denitration efficiency reaches 40%. The flue gas volume of the incineration line under the standard condition is 89580Nm 3 / h, and the flue gas temperature is 200℃.

[0051] 2. Baking soda dry method acid removal

[0052] The baking soda dry method acid removal tower 3 uses the original semi-dry method reaction tower, and the rotary atomizer is disabled, and a baking soda injection system is arranged at the inlet flue. 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 by a grinder, and the output of the grinder is 167kg / h. The fine powder is injected into the acid removal tower through a Roots blower and a lance to react with the acid gases (SO2, HCl, etc.) in the flue gas, and the acid removal efficiency reaches 97%. The baking soda consumption is 8kg / t of waste, and the flue gas temperature is maintained at 200℃.

[0053] 3. Activated carbon injection

[0054] The activated carbon injection system 9 is used for injecting activated carbon into the flue gas pipeline at the inlet of the SCR denitration bag-type dust collector 4, and the injection amount is 0.43kg / t of waste, which adsorbs dioxins and heavy metals in the flue gas, and the dioxin removal rate reaches 99%.

[0055] 4. The SCR denitration bag-type dust collector

[0056] The existing filter bag in the dust collector is replaced with 967 SCR denitration filter bags (specifications Φ160x6000mm), and the filter bag area is 2900m 2 The filtering wind speed is 0.89m / min. The SCR reducing agent evaporation system 10 is used for preparing and spraying ammonia into the flue gas pipeline at the 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 (an air volume of 2500m 3 / h, a pressure of 4200Pa), and an ammonia spraying grid. The reducing agent solution is mixed with hot air generated by a heater to generate ammonia through pyrolysis, the ammonia concentration is controlled to be less than 5%, and the ammonia is sprayed into the flue through the ammonia spraying grid. The NOx in the flue gas reacts with the ammonia under the catalysis of the SCR denitration filter bag, the denitration efficiency reaches 90%, and the particulate matter capture efficiency is greater than 99.99%.

[0057] 5. Waste heat utilization

[0058] A heat exchanger is additionally arranged at the outlet flue of the dust collector, the flue gas inlet temperature is 190℃, the outlet temperature is reduced to 140℃, the heat absorption working medium is low-pressure heater outlet condensate water (80℃), and after heating, the condensate water is returned to the deaerator (110℃). The recovered heat is converted into steam at a quantity of 2.51t / h.

[0059] Operation results:

[0060] After detection, the emission indexes of the treated flue gas are as follows: the SO2 concentration is 5mg / Nm 3 , the NOx concentration is 70mg / Nm 3 , the particulate matter concentration is 10mg / Nm 3 , the ammonia escape concentration is 8mg / Nm 3 , and the dioxin removal rate is 99%. In the case of 8000 hours of annual operation, the fly ash quantity is 11.89t / d, the operation cost per ton of garbage is 55.43 yuan, the total investment is 9.46 million yuan, and the annual operation cost is saved by 5.15 million yuan (compared with a traditional SCR scheme).

[0061] Embodiment 2: 500t / d incineration line high-load operation condition

[0062] In this embodiment, the system in the utility model is applied to flue gas treatment under high-load operation conditions of the same 500t / d incineration line, and the adaptability of the system under the condition of high flue gas quantity and high pollutant concentration is verified. The process flow is the same as that in embodiment 1, and the specific implementation steps are as follows:

[0063] 1. SNCR in-furnace denitration

[0064] 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 increased to 220℃.

[0065] 2. Baking soda dry deacidification

[0066] The dry deacidification tower 3 is a reused original semi-dry reaction tower, and the baking soda injection system remains unchanged. The baking soda coarse powder is ground to D90≤20μm by a grinder, and the injection amount is adjusted to 9.2kg / t of waste to cope 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 below.

[0067] 3. Activated carbon injection

[0068] The activated carbon injection amount is 0.5kg / t of waste, effectively adsorbing dioxin and heavy metals, and the dioxin removal rate is maintained at 99%.

[0069] 4. SCR denitration bag type dust removal

[0070] 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 less than 10mg / Nm 3 .

[0071] 5. Waste heat utilization

[0072] 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.

[0073] Operation results:

[0074] 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.

[0075] 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 system, characterized by: The waste incinerator is sequentially connected with a waste heat boiler, a soda ash dry deacidification tower, an SCR denitration bag-type dust collector, an induced draft fan and a chimney in sequence along a flue gas flow direction. An SNCR system is arranged on the waste incinerator, 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. A soda ash dry powder storage, preparation and spraying system is arranged on the soda ash dry deacidification tower to spray soda ash powder into the soda ash dry deacidification tower to absorb acid gases 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, and an expanded polytetrafluoroethylene film is arranged on an outermost layer of the SCR denitration filter bag, and a composite catalyst felt loaded with a catalyst is arranged on an inner layer of the SCR denitration filter bag.

2. The waste incineration flue gas treatment system according to claim 1, characterized in that: An activated carbon spraying system and an SCR reducing agent evaporation system are arranged on a connecting pipeline between the soda ash dry deacidification tower and the SCR denitration bag-type dust collector, the activated carbon spraying system is used to spray activated carbon to adsorb dioxins and heavy metals, and the SCR reducing agent evaporation system is used to provide a reducing agent for an SCR denitration reaction.

3. The waste incineration flue gas treatment system according to claim 1, characterized in that: A waste heat utilization device is arranged on a connecting pipeline between the SCR denitration bag-type dust collector and the induced draft fan, the waste heat utilization device absorbs heat of 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 system according to claim 1, characterized in that: The soda ash dry powder storage, preparation and spraying system comprises a soda ash storage bin, a soda ash metering module, a grinder, a conveying fan and a spray gun connected in sequence, soda ash coarse powder is ground into fine powder with a fineness D90≤20μm through the grinder after metering, and the fine powder is sprayed into the soda ash dry deacidification tower through the conveying fan and the spray gun.

5. The waste incineration flue gas treatment system according to claim 4, characterized in that: The soda ash dry deacidification tower is provided with sensors for detecting concentrations of SO2 and HCl, the sensors are connected with the soda ash dry powder storage, preparation and spraying system to adjust an amount of soda ash supplied into flue gas.

6. The waste incineration flue gas treatment system according to claim 2, 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 spraying grid, the ammonia spraying grid is arranged on a flue gas pipeline at an outlet of the soda ash dry deacidification tower, and the reducing agent is conveyed to the ammonia spraying grid through the reducing agent conveying module after pyrolysis and gasification.

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