阅读说明：本技术 一种高效减排氮氧化物的垃圾焚烧系统及方法 (Waste incineration system and method for efficiently reducing nitrogen oxides ) 是由 卿梦磊 雷嗣远 王乐乐 杨晓宁 杨万荣 朱仓海 孔凡海 姚燕 马云龙 鲍强 王凯 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种高效减排氮氧化物的垃圾焚烧系统及方法,该系统包括：焚烧炉,内置垃圾焚烧区和二次燃烧区,二级燃烧区内通入废弃塑料和CH-4,CH-4沿垂直于烟气流向通入二次燃烧区内；换热装置；酸性物质及灰分脱除装置；催化反应床；低温换热器；焚烧炉、换热装置、酸性物质及灰分脱除装置、催化反应床和低温换热器由左至右或沿烟气流向依次连通,低温换热器分别与垃圾焚烧区、二次燃烧区和催化反应床连通,分别用于向垃圾焚烧区、二次燃烧区和催化反应床输送换热后的空气。本发明通过采用废弃塑料作为再燃燃料及通入CH-4对冲燃烧的方式,降低烟气中NOx的生成,并通过催化燃烧将烟气中的未燃尽物除去,高效减排氮氧化物效果显著。(The invention discloses a waste incineration system and a method for efficiently reducing nitrogen oxides, wherein the system comprises: an incinerator with a garbage burning region and a secondary combustion region, and waste plastics and CH introduced into the secondary combustion region 4 ，CH 4 Introducing the flue gas into a secondary combustion zone along a direction perpendicular to the flow direction of the flue gas; a heat exchange device; an acid and ash removal device; a catalytic reaction bed; a low temperature heat exchanger; the incinerator, the heat exchange device, the acid substance and ash removal device, the catalytic reaction bed and the low-temperature heat exchanger are sequentially communicated from left to right or along the flow direction of flue gas, and the low-temperature heat exchanger is respectively communicated with the garbage incineration area, the secondary combustion area and the catalytic reaction bed and is respectively used for conveying air subjected to heat exchange to the garbage incineration area, the secondary combustion area and the catalytic reaction bed. The invention adopts waste plastics as reburning fuel and introduces CH 4 The generation of NOx in the flue gas is reduced by the mode of opposed firing, unburnt substances in the flue gas are removed by catalytic combustion, and the effect of efficiently reducing emission of nitrogen oxides is remarkable.)

1. The utility model provides a waste incineration system of high-efficient emission reduction nitrogen oxide which characterized in that includes:

burn burning furnace, set up msw incineration district and postcombustion district in burning furnace, msw incineration district and postcombustion district are linked together and the two sets up along the flue gas flow direction in proper order, let in domestic waste and air in the msw incineration district, let in waste plastics and CH in the secondary combustion district₄Gas, CH₄The gas is introduced into the secondary combustion zone along the direction vertical to the flow direction of the flue gas;

a heat exchange device;

an acid and ash removal device;

a catalytic reaction bed;

a low temperature heat exchanger;

the incinerator, the heat exchange device, the acid substance and ash removal device, the catalytic reaction bed and the low-temperature heat exchanger are sequentially communicated from left to right or along the flow direction of flue gas, and the low-temperature heat exchanger is further communicated with the garbage incineration area, the secondary combustion area and the catalytic reaction bed respectively and is used for conveying air subjected to heat exchange to the garbage incineration area, the secondary combustion area and the catalytic reaction bed respectively.

2. A waste incineration method for efficiently reducing nitrogen oxides is characterized in that the waste incineration system for efficiently reducing nitrogen oxides in claim 1 is adopted for carrying out waste incineration, and the method comprises the following steps:

introducing household garbage and air into the garbage incineration area, discharging dust generated by burning the household garbage in the garbage incineration area through the secondary combustion area, introducing generated flue gas into the secondary combustion area, and introducing waste plastic and CH into the secondary combustion area₄Gas, CH₄The gas is introduced into the secondary combustion zone along the direction perpendicular to the flow direction of the flue gas to ensure that CH is formed₄The gas and the airflow from the garbage burning area are collided to realize the collision burning, the waste plastics are pyrolyzed to generate hydrocarbon groups which collide with NOx in the smoke from the garbage burning area to generate nitrogen-containing intermediates, and partial NOx is converted into N after reduction reaction₂，CH₄C produced by pyrolysisH₃The radicals react with NOx to form N₂(ii) a The temperature of the high-temperature flue gas from the secondary combustion area is 900-₂Removing acid substances including HCl and ash and heavy metal components, then introducing the flue gas into a catalytic reaction bed, controlling the temperature of the catalytic reaction bed at 320-400 ℃, and under the action of a catalyst of the catalytic reaction bed, carrying out catalytic oxidation on unburnt substances in the flue gas to finally generate CO₂And H₂O, introducing the flue gas from the catalytic reaction bed into a low-temperature heat exchanger, exchanging heat with air required by combustion, and discharging the flue gas into the atmosphere when meeting relevant emission standards; air required by combustion is respectively introduced into the waste incineration area, the secondary combustion area and the catalytic reaction bed after heat exchange through the low-temperature heat exchanger, the system efficiency is improved by utilizing heat generated in the catalytic reaction bed, and the air passing through the catalytic reaction bed provides an oxidant for catalytic oxidation of unburnt substances.

3. The waste incineration method for efficiently reducing nitrogen oxides according to claim 2, characterized in that the ratio of the actual air introduction amount to the air amount required for combustion in the waste incineration zone is 1.1-1.2: 1.

4. the waste incineration method for efficiently reducing nitrogen oxides according to claim 2, wherein the amount of oxygen in the waste incineration zone is more than 10% of the amount required by the stoichiometric amount.

5. The method as claimed in claim 2, wherein the excess air ratio in the secondary combustion zone is 0.8-0.9, and the temperature is controlled at 1000-1100 ℃.

6. The waste incineration method for efficiently reducing nitrogen oxides according to claim 2, characterized in that the catalysis is performedThe catalyst in the reaction bed adopts TiO₂A catalyst.

Technical Field

The invention belongs to the technical field of waste incineration power generation, and particularly relates to a waste incineration system and method for efficiently reducing nitrogen oxides.

Background

The household garbage incineration power generation is an important means for treating urban household garbage in China as a harmless, quantitative-reduction and resource-recycling garbage disposal mode, but the household garbage incineration power generation also faces many problems. For example, garbage incineration generates a large amount of nitrogen oxides (NOx), and is liable to cause a series of environmental problems such as photochemical smog, acid rain, greenhouse effect, ozone layer destruction and the like. At present, measures for reducing NOx emission mainly comprise a low-nitrogen combustion technology and a flue gas denitration technology after combustion. Wherein the low-nitrogen combustion technology comprises air classification, flue gas recirculation and a low-nitrogen combustor; flue gas denitration techniques include Selective Catalytic Reduction (SCR) and selective non-catalytic reduction (SNCR). Tianjin issued emission standards (draft of comments) for atmospheric pollutants from incineration of household garbage, and a factory in incineration of household garbage intends to execute a specified emission limit for atmospheric pollutants according to the standards from 1 month and 1 day 2023. Wherein the NOx emission concentration is limited from 300mg/m³Tightened to 120mg/m³. Modern large-scale waste incineration is generally provided with an SNCR denitration system, but the denitration efficiency of the method is usually only 30% -45%, so that the elimination of NOx needs to be enhanced in the aspects of front-end waste fuel treatment, combustion mode and the like.

With the continuous development of industry, waste plastics become a non-negligible part of solid waste garbage. The main component of the waste plastic is polyethylene, has good combustion characteristic, and has the characteristics of high heat value, high volatile matter, high combustion speed and the like. When the fuel is used as reburning fuel, the hydrocarbon groups generated by pyrolysis can perform reduction reaction with NOx, and the emission of the NOx is reduced. Therefore, the waste plastics are added into the household garbage incineration system, so that the emission of NOx can be reduced, the cost and the storage danger of waste plastics landfill can be avoided, and considerable social and economic benefits are achieved.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention aims to provide a waste incineration system and method for efficiently reducing nitrogen oxide emission.

In order to achieve the purpose and achieve the technical effect, the invention adopts the technical scheme that:

a waste incineration system for efficiently reducing nitrogen oxides comprises:

burn burning furnace, set up msw incineration district and postcombustion district in burning furnace, msw incineration district and postcombustion district are linked together and the two sets up along the flue gas flow direction in proper order, let in domestic waste and air in the msw incineration district, let in waste plastics and CH in the secondary combustion district₄Gas, CH₄The gas is introduced into the secondary combustion zone along the direction vertical to the flow direction of the flue gas;

a heat exchange device;

an acid and ash removal device;

a catalytic reaction bed;

a low temperature heat exchanger;

the incinerator, the heat exchange device, the acid substance and ash removal device, the catalytic reaction bed and the low-temperature heat exchanger are sequentially communicated from left to right or along the flow direction of flue gas, and the low-temperature heat exchanger is further communicated with the garbage incineration area, the secondary combustion area and the catalytic reaction bed respectively and is used for conveying air subjected to heat exchange to the garbage incineration area, the secondary combustion area and the catalytic reaction bed respectively.

A waste incineration method for efficiently reducing nitrogen oxides comprises the following steps:

introducing household garbage and air into the garbage incineration area, discharging dust generated by burning the household garbage in the garbage incineration area through the secondary combustion area, introducing generated flue gas into the secondary combustion area, and introducing waste plastic and CH into the secondary combustion area₄Gas, CH₄Gas is introduced twice along the direction perpendicular to the flow direction of the flue gasIn the combustion zone, make CH₄The gas and the airflow from the garbage burning area are collided to realize the collision burning, the waste plastics are pyrolyzed to generate hydrocarbon groups which collide with NOx in the smoke from the garbage burning area to generate nitrogen-containing intermediates, and partial NOx is converted into N after reduction reaction₂，CH₄Pyrolysis of generated CH₃The radicals react with NOx to form N₂(ii) a The temperature of the high-temperature flue gas from the secondary combustion area is 900-₂Removing acid substances including HCl and ash and heavy metal components, then introducing the flue gas into a catalytic reaction bed, controlling the temperature of the catalytic reaction bed at 320-400 ℃, and under the action of a catalyst of the catalytic reaction bed, carrying out catalytic oxidation on unburnt substances in the flue gas to finally generate CO₂And H₂O, introducing the flue gas from the catalytic reaction bed into a low-temperature heat exchanger, exchanging heat with air required by combustion, and discharging the flue gas into the atmosphere when meeting relevant emission standards; air required by combustion is respectively introduced into the waste incineration area, the secondary combustion area and the catalytic reaction bed after heat exchange through the low-temperature heat exchanger, the system efficiency is improved by utilizing heat generated in the catalytic reaction bed, and the air passing through the catalytic reaction bed provides an oxidant for catalytic oxidation of unburnt substances.

Further, the ratio of the actual air inlet amount in the waste incineration area to the air amount required by combustion is 1: 1.

further, the amount of oxygen in the waste incineration zone is more than 10% of the amount stoichiometrically required.

Further, the excess air coefficient in the secondary combustion zone is 0.8-0.9, and the temperature is controlled at 1000-1100 ℃.

Further, the catalyst in the catalytic reaction bed adopts TiO₂A catalyst.

Furthermore, the waste plastics account for 20% of the amount of the incineration waste, and the equivalent ratio of the amount of the methane to NOx generated by waste incineration is 1: 1.

compared with the prior art, the invention has the beneficial effects that:

1) the invention introduces waste plastics and CH into a secondary combustion zone₄And the amount of the fuel is larger than the stoichiometric ratio to form a fuel-rich zone which is a reducing atmosphere, the excess air coefficient in the secondary combustion zone is kept between 0.8 and 0.9, and the temperature is controlled at 1000-1100 ℃; the waste plastics mainly contain polyethylene, and the pyrolysis of the polyethylene produces CH₂、C₂H₅、C₂H₃And the like. Polyethylene is decomposed by heat to produce hydrocarbon radicals, such as-CH₂、-C₂H₅、-C₂H₃And the groups collide with NOx in the smoke from the waste incineration area to generate corresponding nitrogen-containing intermediates, the nitrogen-containing intermediates and reducing groups undergo reduction reaction, and finally part of NOx is converted into N₂；

2) The invention preferably adopts a mode of up-down opposed firing in the secondary combustion zone, and methane (CH) is injected at the upper end₄) On the one hand let CH₄The gas flow coming out from the garbage burning area is in opposite impact to form a complex flowing condition, so that the whole speed of the gas flow coming out from the garbage burning area is slowed down, the residence time of the flue gas is increased, the removal of dioxin is facilitated, and on the other hand, the CH can be increased in an opposite impact mode₄Contact with flue gases from the waste incineration zone, CH₄Pyrolysis to produce CH₃The group can react with NOx in the flue gas to generate an intermediate HCN, and the HCN finally generates N through reduction reaction₂；

3) Air required by combustion is firstly subjected to heat exchange through the low-temperature heat exchanger and then is respectively introduced into the waste incineration area, the secondary combustion area and the catalytic reaction bed, so that heat generated in the catalytic reaction bed can be utilized, and the system efficiency is improved. Wherein air passing through the catalyst bed provides an oxidant for catalytic oxidation of the unburnt matter;

4) the catalyst in the catalytic reaction bed is TiO₂The product is beautiful and cheap, and is easy to prepare and regulate. In the secondary combustion zone due to waste plastics and CH₄The remaining part of unburnt substances after the reaction of the formed reducing groups with NOx can be catalytically oxidized in a catalytic reaction bed to finally generate CO₂And H₂O。

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

Detailed Description

The present invention is described in detail below with reference to the attached drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby clearly defining the protection scope of the present invention.

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

In the description of the present invention, it should be noted that the terms "top", "bottom", "left", "right", "upper", "lower", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on orientations or positional relationships shown in the drawings or orientations or positional relationships that the products of the present invention are conventionally placed in use, which are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention.

As shown in fig. 1, a waste incineration system for efficiently reducing nitrogen oxides includes:

the incinerator 1 is provided with a garbage incineration area 11 and a secondary combustion area 12 in the incinerator 1; the garbage burning area 11 is communicated with the secondary combustion area 12 and the two areas are sequentially arranged along the flow direction of the flue gas, domestic garbage and air are introduced into the garbage burning area 11, and waste plastic and CH are introduced into the secondary combustion area 12₄，CH₄Is introduced into the secondary combustion zone 12 along the direction vertical to the flow direction of the flue gas; the ratio of the actual air inlet amount in the waste incineration area 11 to the air amount required by combustion is 1.1-1.2: 1;

the heat exchange device 2 comprises a water wall 21, a superheater 22 and an economizer 23 which are sequentially arranged along the flow direction of the flue gas;

the device 3 for removing the acidic substance and the ash content comprises a rotary spraying semi-dry reaction tower 31, a bag-type dust remover 32 and a wet washing tower 33 which are sequentially arranged along the flow direction of the flue gas;

a catalytic reaction bed 4, TiO is arranged in the catalytic reaction bed 4₂A catalyst;

a low temperature heat exchanger 5;

the incinerator 1, the heat exchange device 2, the acidic substance and ash removal device 3, the catalytic reaction bed 4 and the low-temperature heat exchanger 5 are sequentially communicated from left to right or along the flow direction of flue gas, and the low-temperature heat exchanger 5 is further communicated with the garbage incineration area 11, the secondary combustion area 12 and the catalytic reaction bed 4 respectively and used for conveying air subjected to heat exchange to the garbage incineration area 11, the secondary combustion area 12 and the catalytic reaction bed 4.

The garbage incineration area 11 is used for introducing household garbage and air to be incinerated, and the amount of the introduced air needs to be controlled so that the amount of oxygen is greater than 10% of the amount required by the stoichiometric amount, so that the household garbage is combusted easily, and oxygen is provided for the reaction in the secondary combustion area 12; the dust that domestic waste produced in the burning of waste incineration zone 11 landing through the action of gravity to second grade combustion zone 12 bottom and discharge, the flue gas that produces gets into second grade combustion zone 12, lets in waste plastic in second grade combustion zone 12, and the volume of control waste plastic makes the volume of fuel be greater than the stoichiometric ratio, and then forms fuel-rich area, and this fuel-rich area is under reducing atmosphere. Pyrolysis of waste plastics to produce hydrocarbon radicals, such as-CH₂、-C₂H₅、-C₂H₃And the groups collide with NOx in the smoke from the waste incineration area to generate corresponding nitrogen-containing intermediates, the nitrogen-containing intermediates and reducing groups undergo reduction reaction, and finally part of NOx is converted into N₂. At the same time, methane CH is injected from top to bottom into the top of the secondary combustion zone 12₄Let CH₄The gas flow from the garbage incineration area is collided to realize the collision combustion, so as to form a complex flow condition and increase CH₄Contact with flue gas generated by burning household garbage，CH₄Pyrolysis of generated CH₃The radicals and NOx are subjected to reduction reaction to finally generate N₂On the other hand, the gas flow rate is reduced, so that the retention time of the flue gas in the secondary combustion zone 12 is prolonged, and the removal of dioxin is facilitated; the high-temperature flue gas from the secondary combustion zone 12 enters a heat exchange device 2; in the heat exchange device 2, the feed water and the high-temperature flue gas exchange heat to generate steam for power generation; introducing the flue gas after heat exchange into an acid substance and ash removing device 3 to remove SO₂Removing acidic substances such as HCl and the like and components such as ash and heavy metals, and then introducing the flue gas into a catalytic reaction bed 4, wherein the catalyst in the catalytic reaction bed 4 is TiO₂The temperature of the catalytic reaction bed 4 is controlled at 320-400 ℃ in the presence of the catalyst TiO₂Under the action of the catalyst, the unburnt substances in the flue gas are catalytically oxidized to finally generate CO₂And H₂O; the temperature of the flue gas from the catalytic reaction bed 4 is still high, in order to fully utilize the heat contained in the flue gas, the flue gas from the catalytic reaction bed 4 is introduced into the low-temperature heat exchanger 5 to exchange heat with the air required by combustion, because the pollutant content of the flue gas is very low, even if the flue gas meets the relevant emission standard, the flue gas is discharged into the atmosphere, and the air required by combustion is introduced into the garbage incineration zone 11, the secondary combustion zone 12 and the catalytic reaction bed 4 respectively after heat exchange, so that the heat generated in the catalytic reaction bed 4 can be utilized, the system efficiency is improved, wherein the air passing through the catalytic reaction bed 4 provides an oxidant for the catalytic oxidation of unburnt substances.

Waste plastics and CH are introduced into the secondary combustion zone 12₄And the fuel quantity is made to be larger than the stoichiometric ratio, a fuel-rich zone is formed, the fuel-rich zone is a reducing atmosphere, the excess air coefficient in the secondary combustion zone 12 is kept between 0.8 and 0.9, and the temperature is controlled to be 1000-1100 ℃. The waste plastics mainly contain polyethylene, and the pyrolysis of the polyethylene produces CH₂、C₂H₅、C₂H₃And the like. Polyethylene is decomposed by heat to produce hydrocarbon radicals, such as-CH₂、-C₂H₅、-C₂H₃And the groups collide with NOx in the smoke from the waste incineration area to generate corresponding nitrogen-containing intermediates, and the nitrogen-containing intermediates and the reducing groups are subjected to reductionBy primary reaction, with eventual conversion of part of the NOx to N₂The principle is as follows:

∑C_iH_j+NO→HCN+…→N₂

hydrocarbon radical C_iH_jIs mainly CH₂、C₂H₅、C₂H₃In the fuel rich zone they tend to react with NOx, with the detailed reaction steps:

CH₂+NO→H+HNCO

C₂H₅+NO→HCN+CH₃OH

C₂H₃+NO→HCN+CH₂O

HCN+O→NCO+H

NCO+H→NH+CO

NH+H→N+H₂

N+NO→N₂+O。

the invention discloses a waste incineration method for efficiently reducing nitrogen oxide emission, which adopts waste plastics as reburning fuel and introduces CH₄The method for the opposed firing reduces the generation of NOx in the flue gas, and removes unburnt substances in the flue gas by the catalytic firing, and specifically comprises the following steps:

the household garbage is placed in the garbage burning area 11 of the incinerator 1 for burning, the amount of the introduced air is controlled, so that the amount of oxygen is 10% more than the amount required by the stoichiometric amount, dust generated by the combustion of the household garbage in the garbage incineration zone 11 slides to the bottom in the secondary combustion zone 12 under the action of gravity and is discharged, the generated flue gas enters the secondary combustion zone 12, waste plastics are introduced into the secondary combustion zone 12, the amount of the waste plastics is controlled to ensure that the amount of the fuel is larger than the stoichiometric ratio, so that a fuel-rich zone is formed, the fuel-rich area is in reducing atmosphere, the temperature of the generated flue gas leaving the incinerator 1 is 900-1000 ℃, after heat exchange through the water-cooled wall 21, the temperature of the flue gas is reduced to about 570 ℃, then the temperature of the flue gas is reduced to 340-; the flue gas enters an acid substance and ash removal device 3 after being subjected to heat exchange through a heat exchange device 2; in thatLime slurry is sprayed into the rotary spraying semi-dry type reaction tower 31 and is mixed with SO in the flue gas₂The pollutants such as HCl and HF and the like are subjected to neutralization reaction, dioxin and heavy metal are condensed at the same time, and reaction products fall into the bottom of the rotary spray semi-dry reaction tower 31 and are discharged from the bottom; introducing activated carbon into a pipeline between a rotary spraying semi-dry type reaction tower 31 and a bag-type dust remover 32 for absorbing dioxin and mercury in flue gas, wherein the bag-type dust remover 32 can separate dust and solid particles in the flue gas, discharging clean flue gas at an outlet, simultaneously, dust adhered in the bag-type dust remover 32 contains lime slurry, so that the dust can be continuously neutralized and adsorbed with harmful substances in the dust, purging is needed by a pulse soot blower after the operation is carried out for a period of time, injecting NaOH solution into a wet type washing tower 33 to carry out chemical reaction with acid gases such as SOx, HCl and HF in the flue gas, further absorbing the acid gases in the flue gas while dehumidifying, then introducing the flue gas into a catalytic reaction bed 4, controlling the temperature of the catalytic reaction bed 4 to be 320-400 ℃, and introducing TiO catalyst into a catalytic reaction bed 32₂Under the action of the catalyst, the unburnt substances in the flue gas are catalytically oxidized to finally generate CO₂And H₂O; the temperature of the flue gas from the catalytic reaction bed 4 is still high, in order to fully utilize the heat contained in the flue gas, the flue gas from the catalytic reaction bed 4 is introduced into the low-temperature heat exchanger 5 to exchange heat with the air required by combustion, because the pollutant content of the flue gas is very low, even if the flue gas meets the relevant emission standard, the flue gas is discharged into the atmosphere, and the air required by combustion is introduced into the garbage incineration zone 11, the secondary combustion zone 12 and the catalytic reaction bed 4 respectively after heat exchange, so that the heat generated in the catalytic reaction bed 4 can be utilized, the system efficiency is improved, wherein the air passing through the catalytic reaction bed 4 provides an oxidant for the catalytic oxidation of unburnt substances.

The parts of the invention not specifically described can be realized by adopting the prior art, and the details are not described herein.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by the present specification, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.