阅读说明：本技术 一种废弃scr脱硝催化剂资源化利用方法 (Resource utilization method of waste SCR denitration catalyst ) 是由 王乐乐 何川 姚燕 孔凡海 杨晓宁 宋玉宝 吴国勋 张发捷 雷嗣远 王凯 王丽朋 于 2020-11-06 设计创作，主要内容包括：本发明涉及一种废弃SCR脱硝催化剂资源化利用方法,包括取出废弃SCR脱硝催化剂,对其破碎至指定粒径的块体或颗粒,将破碎后的废弃SCR脱硝催化剂按照锅炉入炉煤总量不大于5.0%的质量比例与煤粉进行混合,将混合后的废弃SCR脱硝催化剂、煤粉送入液态排渣锅炉燃烧室,经1300℃-2000℃的温度燃烧后形成熔融态的液态流渣,通过急速冷却形成玻璃态固化体。本发明改善了锅炉燃烧状况,投资少,能耗低、运行成本低,单位时间内处置效率高,可改善锅炉燃料的着火、燃尽特性,提高锅炉煤种适应性,降低锅炉炉内氮氧化物的生成,减轻下游烟气SCR脱硝运行压力,推广应用具有较好的节能减排价值。(The invention relates to a resource utilization method of a waste SCR denitration catalyst, which comprises the steps of taking out the waste SCR denitration catalyst, crushing the waste SCR denitration catalyst into blocks or particles with specified particle sizes, mixing the crushed waste SCR denitration catalyst with coal powder according to the mass proportion that the total amount of boiler coal fed into a boiler is not more than 5.0%, feeding the mixed waste SCR denitration catalyst and the coal powder into a liquid slag-discharging boiler combustion chamber, burning at 1300-2000 ℃ to form molten liquid slag, and rapidly cooling to form a glass-state solidified body. The invention improves the combustion condition of the boiler, has the advantages of low investment, low energy consumption, low operation cost and high treatment efficiency in unit time, can improve the ignition and burnout characteristics of boiler fuel, improve the adaptability of boiler coal types, reduce the generation of nitrogen oxides in the boiler, reduce the SCR denitration operation pressure of downstream flue gas, and has better energy-saving and emission-reducing values when being popularized and applied.)

1. A resource utilization method of a waste SCR denitration catalyst is characterized by comprising the following steps: the method comprises the following steps:

s1: taking out the waste SCR denitration catalyst, crushing the waste SCR denitration catalyst into blocks or particles with specified particle size,

s2: mixing the crushed waste SCR denitration catalyst with coal powder according to the mass proportion that the total amount of the boiler coal is not more than 5.0%,

s3: and feeding the mixed waste SCR denitration catalyst and coal powder into a combustion chamber of a slag tapping boiler, combusting at 1300-2000 ℃ to form molten liquid slag, and rapidly cooling to form a glassy solidified body.

2. The resource utilization method of the waste SCR denitration catalyst according to claim 1, characterized in that: in the waste SCR denitration catalyst: TiO 2₂Not less than 75.0% by mass, V₂O₅0 to 5.0 percent of CaO, 0 to 6.0 percent of Fe₂O₃The mass percentage content of the MgO is 0-3.0%, and the mass percentage content of the MgO is 0-3.0%.

3. The resource utilization method of the waste SCR denitration catalyst according to claim 2, characterized in that: in the waste SCR denitration catalyst: TiO 2₂Not less than 83.0% by mass, V₂O₅0.5-1.5 percent of the total weight of the alloy, 1.0-2.0 percent of CaO and Fe₂O₃The mass percentage content of the MgO is 0.05-1.0%, and the mass percentage content of the MgO is 0.05-1.0%.

4. The resource utilization method of the waste SCR denitration catalyst according to claim 1, characterized in that: the waste SCR denitration catalyst is mixed with coal powder according to the mass proportion of 1.5-5.0% of the total amount of coal as fired in the boiler.

5. The resource utilization method of the waste SCR denitration catalyst according to claim 1, characterized in that: when the waste SCR catalyst is a honeycomb denitration catalyst or a flat-plate denitration catalyst, crushing the waste SCR catalyst into blocks or particles with the particle size of not more than 20 mm; when the waste SCR catalyst is a corrugated plate type denitration catalyst, the waste SCR catalyst is crushed into particle powder with the particle size not larger than 10 mm.

6. The resource utilization method of the waste SCR denitration catalyst according to claim 5, characterized in that: crushing the honeycomb type and corrugated plate type denitration catalysts by a crusher; the flat plate type denitration catalyst adopts bending and vibration stripping modes to lead the oxide substances in the denitration catalyst to fall off from the wire mesh base material.

7. The resource utilization method of the waste SCR denitration catalyst according to claim 1, characterized in that: the crushed waste SCR denitration catalyst is uniformly added into a belt of a coal feeder of a boiler through a feeding device, and the adding amount of the waste SCR denitration catalyst is adjusted through the rotating speed of the feeding device.

8. The resource utilization method of the waste SCR denitration catalyst according to claim 7, characterized in that: the waste SCR catalyst and the pulverized coal enter a coal mill through a coal mill belt to be fully ground and uniformly mixed, and then enter the liquid slag-discharging boiler combustion chamber along with hot air.

9. The resource utilization method of the waste SCR denitration catalyst according to claim 1, characterized in that: and the molten liquid slag falls into a slag chamber at the bottom of the boiler and is rapidly cooled.

10. The resource utilization method of the waste SCR denitration catalyst according to claim 1, characterized in that: the glass state solidified body is used as a raw material to be processed into baking-free bricks, road building materials and ceramics.

Technical Field

The invention belongs to the field of energy conservation and environmental protection of a new technology for treating solid waste of a thermal power plant, and particularly relates to a resource utilization method of a waste SCR denitration catalyst.

Background

Selective Catalytic Reduction (SCR) denitration technology is the most commonly used denitration technology for controlling the emission of nitrogen oxides in flue gas of the current thermal power plant. Under the influence of physical, chemical and other poisoning factors in the using process, the catalyst is finally scrapped after long-term service. According to the requirement of the department of ecology "notice on monitoring work for strengthening waste flue gas denitration catalyst" (No. 2014 990), the waste flue gas denitration catalyst (vanadium-titanium system) is brought into hazardous waste for management, and the regeneration, utilization and disposal capability of the waste flue gas denitration catalyst (hereinafter referred to as "waste SCR catalyst") is required to be improved as soon as possible.

The catalyst is the core of SCR denitration equipment, and commercial SCR denitration catalysts are mainly vanadium-titanium-tungsten (molybdenum) series and mainly comprise titanium dioxide (TiO)₂) Is a carrier, usually more than 75% of vanadium pentoxide (V) in mass ratio of the catalyst₂O₅) And tungsten trioxide (V)₂O₅) Molybdenum trioxide (MoO)₃) Respectively an active substance and an effective auxiliary agent. According to the related studies, TiO in the catalyst₂、V₂O₅Etc. may be not only in NH₃The catalyst plays a role in selective catalyst reduction in NO chemical reaction, and can play a role in promoting the catalytic combustion of pulverized coal particle ignition and burnout in a certain temperature window. In the using process of the denitration catalyst, due to the existence of fly ash in the flue gas of the coal-fired boiler, the catalyst which is in service for a long time is finally deactivated because the performance of the catalyst is gradually reduced due to the accumulation of a large amount of toxic and harmful substances on the surface and in micropores of the catalyst. The waste catalyst contains TiO₂、V₂O₅And WO₃/MoO₃In addition, it also contains a certain mass of SiO₂、Al₂O₃、Na₂O、K₂O、SO₃、CaO、Fe₂O₃And oxides such As MgO, CuO, HgO, PbO, As₂O₃And the harm of harmful substances such as NiO and the like to the environment is mainly expressed as leaching toxicity, and if the harmful substances are disposed randomly, the harmful substances can bring long-term potential secondary pollution to underground water and soil.

At present, waste SCR catalysts without regeneration value are generally disposed and utilized by means of safe landfill and extraction and recycling of valuable metals in the waste SCR catalysts by enterprises with disposal qualification and capability at the downstream.

The patent with publication number CN106311218A discloses a vanadium-based SCR catalyst regenerated catalyst powder and a preparation method thereof, but the regeneration times of the catalyst and the activity recovery of the regenerated powder are limited, the performance of the regenerated powder is unstable, and the problems of complicated regeneration process, high waste water and waste residue disposal cost in the regeneration process and the like exist.

Patent publication No. CN104926235A discloses a method for treating and curing waste SCR denitration catalyst before landfill, which occupies a large amount of land resources for safe landfill and does not meet the sustainable development requirement.

The patent with publication number CN110548748A discloses a method for treating waste SCR flue gas denitration catalyst and fly ash by cooperative melting, which needs a special high-temperature melting device, has the problems of high energy consumption, low efficiency and the like due to the addition of additives for ensuring the heavy metal solidification effect, the high-temperature melting treatment time longer than 60 minutes and the like, and only realizes the cooperative harmless treatment of the waste SCR catalyst and the fly ash, but does not realize the resource utilization, thereby causing resource waste.

The slag tapping boiler is named after a slag which is formed by burning coal powder into a molten state to form liquid flow by utilizing a special hearth structure and extremely high flame temperature in a combustion chamber. The temperature in the combustion chamber in the normal combustion process can reach 1300-2000 ℃, liquid slag formed in the combustion process can form a compact glass state sintered body after falling into a furnace bottom slag chamber and being cooled, and harmful substances such as heavy metal and the like can be solidified in a compact vitrification grid in the forming process of the sintered body, so that the volume reduction and solidification of solid waste are realized.

Disclosure of Invention

The invention aims to provide a resource utilization method of a waste SCR denitration catalyst, which is suitable for a liquid-state slagging boiler, fully utilizes the characteristics and advantages of the existing liquid-state slagging boiler, takes the waste SCR denitration catalyst as a boiler pulverized coal combustion additive, thereby realizing the improvement of the combustion characteristics of boiler fuel and the improvement of coal adaptability, effectively inhibiting the leaching of heavy metals in the waste catalyst while reducing the generation of nitrogen oxides in the combustion process of the boiler, and further realizing the harmless disposal and resource utilization of the waste catalyst.

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

a resource utilization method of a waste SCR denitration catalyst comprises the following steps:

s1: taking out the waste SCR denitration catalyst, crushing the waste SCR denitration catalyst into blocks or particles with specified particle size,

s2: mixing the crushed waste SCR denitration catalyst with coal powder according to the mass proportion that the total amount of the boiler coal is not more than 5.0%,

s3: and feeding the mixed waste SCR denitration catalyst and coal powder into a combustion chamber of a slag tapping boiler, combusting at 1300-2000 ℃ to form molten liquid slag, and rapidly cooling to form a glassy solidified body.

In the present application: the ignition temperature of the mixed waste SCR denitration catalyst and coal dust is reduced by 0-15 ℃ compared with that when the waste catalyst is not doped, and the burnout temperature is reduced by 0-25 ℃ compared with that when the waste catalyst is not doped, so that the ignition and burnout of the coal dust are facilitated; the concentration of nitrogen oxides (NOx) formed during combustion is reduced by 0mg/m compared to when no spent catalyst is incorporated³-180mg/m³And the generation of gaseous pollutants in the combustion process is reduced.

Preferably, in the waste SCR denitration catalyst: TiO 2₂Not less than 75.0% by mass, V₂O₅0 to 5.0 percent of CaO, 0 to 6.0 percent of Fe₂O₃The mass percentage content of the MgO is 0-3.0%, and the mass percentage content of the MgO is 0-3.0%.

Further preferably, in the waste SCR denitration catalyst: TiO 2₂Not less than 83.0% by mass, V₂O₅0.5-1.5 percent of the total weight of the alloy, 1.0-2.0 percent of CaO and Fe₂O₃The mass percentage content of the MgO is 0.05-1.0%, and the mass percentage content of the MgO is 0.05-1.0%.

Preferably, the waste SCR denitration catalyst is mixed with coal powder according to the mass ratio of 1.5-5.0% of the total amount of coal as fired in the boiler.

Preferably, when the waste SCR catalyst is a honeycomb denitration catalyst or a flat-plate denitration catalyst, the waste SCR catalyst is crushed into blocks or particles with the particle size of not more than 20 mm; when the waste SCR catalyst is a corrugated plate type denitration catalyst, the waste SCR catalyst is crushed into particle powder with the particle size not larger than 10 mm.

Further preferably, the honeycomb type and corrugated plate type denitration catalysts are crushed by a crusher; the flat plate type denitration catalyst adopts bending and vibration stripping modes to lead the oxide substances in the denitration catalyst to fall off from the wire mesh base material.

Preferably, the crushed waste SCR denitration catalyst is uniformly added into a belt of a coal feeder of a boiler through a feeding device, and the adding amount of the waste SCR denitration catalyst is adjusted through the rotating speed of the feeding device.

Further preferably, the waste SCR catalyst and the pulverized coal enter a coal mill through a coal mill belt, are fully ground and uniformly mixed, and then enter the combustion chamber of the slagging tap boiler along with hot air.

Preferably, the molten liquid slag falls into a furnace bottom slag chamber of the boiler and then is rapidly cooled to form a compact glass state solidified body, the volume reduction of the slag can be realized by more than 50%, the solidified body can seal heavy metal toxic substances in the waste SCR catalyst in a self glass body, the leaching of the heavy metal in the waste SCR catalyst is effectively inhibited, the toxic leaching concentration of the solidified body meets the limit requirement of hazardous waste identification standard leaching toxicity identification (GB5085.3-2007), and the harmlessness of the waste SCR denitration catalyst is realized.

Preferably, the glass solidified body is used as a raw material to be processed into baking-free bricks, road building materials, ceramics and the like for resource utilization.

The waste SCR denitration catalyst is crushed to a certain degree, is added into a coal-fired boiler coal feeding system according to a certain mass proportion, is fully ground and uniformly mixed with coal powder, and then enters a boiler hearth to serve as a coal-fired additive to promote ignition and burnout of the coal powder and reduce generation of nitrogen oxides at the initial stage of combustion, and a compact glassy slag solidified body is formed by utilizing the high-temperature melting characteristic of a liquid slag-discharging boiler and is finally used as a building material in the industries of road building, building materials and the like, so that harmless treatment and resource utilization of the waste SCR catalyst are realized.

TiO₂Has the functions of promoting the combustion of pulverized coal and denitration reaction in the combustion process, and the TiO in the waste SCR denitration catalyst₂The activation energy in the combustion reaction process of the boiler pulverized coal can be reduced, the oxidation and volatilization of carbon in the pulverized coal can be promoted in the reaction process, so that the combustion reaction is promoted, the generation of products in the amino group in the pulverized coal in the initial combustion stage is accelerated, the reducing atmosphere in the combustion region is provided, the NOx self-reduction capability in the initial combustion stage is improved, and the generation of nitrogen oxides in the boiler is inhibited. In addition, CaO and Fe in a certain mass ratio in the waste catalyst₂O₃And oxides such as MgO and the like can be used as an auxiliary agent to promote the cracking of volatile hydrocarbon substances in the coal dust so as to promote combustion, and also can play a role of a sintering agent auxiliary agent to promote toxic heavy metal elements in the waste catalyst to form a complex intermediate which is difficult to leach, so that the solidification and toxicity reduction effects in the high-temperature melting process are realized.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:

1. based on the typical slag tapping boiler of the existing coal-fired power plant, the waste SCR denitration catalyst is added into a fuel conveying system as a boiler combustion additive, the combustion condition of the boiler is improved by fully utilizing the catalyst combustion effect of the waste catalyst and the high-temperature melting and slagging characteristics of the slag tapping boiler, and the high-temperature solidification, harmlessness and reduction of heavy metals in the waste catalyst are realized, so that the waste is changed into valuable, and a new method is provided for the disposal and utilization of the waste SCR denitration catalyst;

2. according to the invention, a special high-temperature smelting furnace is not required to be additionally arranged, the mixture of the waste SCR denitration catalyst and the coal powder is burnt into a compact glass state solidified body by utilizing the high-temperature melting characteristic of the liquid slag-off boiler of the existing thermal power plant, and an additional additive is not required to be additionally added, so that the method has the advantages of low investment, low energy consumption and low operation cost; in addition, the mixture of the pulverized coal and the waste catalyst has short combustion residence time in the hearth, and has the advantage of high treatment efficiency in unit time;

3. the waste SCR denitration catalyst is used as a boiler combustion additive, so that the ignition and burnout characteristics of boiler fuel can be improved, the adaptability of boiler coal is improved, the generation of nitrogen oxide (NOx) in a boiler can be reduced to a certain extent, the SCR denitration operation pressure of downstream flue gas is reduced, and the waste SCR denitration catalyst has better energy-saving and emission-reducing values in popularization and application;

4. the mixing of the waste SCR catalyst in a certain mass proportion has no influence on the flow characteristic of the slag of the liquid-state slagging boiler and the characteristic of the final product glassy solidified body slag.

Drawings

FIG. 1 is a process flow diagram of the present invention;

FIG. 2 shows the slag of a conventional pulverized coal furnace under scanning by an electron microscope;

FIG. 3 shows the glass-state slag of the liquid slag tapping furnace under scanning of an electron microscope;

FIG. 4 is a conventional pulverized coal furnace slag;

FIG. 5 shows the vitreous slag of the liquid slag tapping furnace.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The resource utilization method of the waste SCR denitration catalyst shown in FIG. 1 comprises the following steps:

firstly, taking out a waste SCR denitration catalyst from a denitration module, wherein the waste SCR catalyst is a honeycomb type denitration catalyst, a flat plate type denitration catalyst and a corrugated plate type denitration catalyst, and the honeycomb type denitration catalyst and the corrugated plate type denitration catalyst can be directly crushed into blocks and particles with the particle size of not more than 20mm by a crusher; for the flat plate type denitration catalyst, the oxidation substances in the waste catalyst fall off from the wire mesh base material by adopting bending and vibration stripping modes, and the particle powder with the particle size not larger than 10mm is obtained.

And then uniformly adding the crushed waste SCR denitration catalyst particles or powder into a boiler coal feeder belt through a feeding device according to the mass ratio of 0-5.0% of the total coal charged into the boiler, adjusting the adding amount of the waste SCR denitration catalyst through the rotating speed of the feeding device, fully grinding and uniformly mixing the mixed material of the waste SCR catalyst and the coal powder entering a coal mill through the coal feeder belt, and then entering a liquid-state slagging boiler combustion chamber along with hot air.

And finally, after the waste SCR denitration catalyst and the coal powder are combusted at the high temperature of 1300-2000 ℃ in the combustion chamber, the molten liquid slag is formed and falls into a slag chamber at the bottom of the boiler, and then the molten liquid slag is rapidly cooled to form a compact glass state solidified body.

Example (b):

in the embodiment, a typical 300MW unit slagging-off boiler is taken as an example, the total amount of coal fed into the boiler under the rated load of the boiler is 100t/h, and the mass of the added waste SCR denitration catalyst is 0-5 t/h.

The waste SCR denitration catalyst is used as a boiler combustion additive to be doped into coal powder, the adopted waste SCR denitration catalyst is respectively in a honeycomb type and a flat plate type, and the chemical composition of the waste SCR denitration catalyst is as follows:

the coal as fired is coal quality 1 and coal quality 2 commonly used by a liquid state slag discharging boiler, and the amount of the sample 1 and the sample 2 doped with the waste SCR denitration catalyst are respectively 0%, 1.5%, 3.0% and 5.0% of the total mass of the coal as fired, wherein the 0% doping ratio is a reference comparison sample. According to a thermogravimetric TG curve and a differential thermogravimetric DTG curve obtained by a thermogravimetric analysis method, the ignition temperature and the burnout temperature of the pulverized coal under different doping ratios are determined to be shown by numerical values in the following table:

the coal as fired is coal quality 1 and coal quality 2 commonly used by a liquid slag removal boiler, and the amount of the sample 1 and the sample 2 doped with the waste SCR denitration catalyst is 0 percent, 1.5 percent, 3.0 percent and 5.0 percent of the total mass of the coal as fired respectively. According to the test of a flue gas analyzer in a fixed bed combustion test in a laboratory, the concentration of nitrogen oxides (NOx) generated in the combustion process under the mixing ratio of different waste SCR denitration catalysts is shown as the numerical values in the following table:

the combustion temperature in the combustion chamber is 1300-2000 ℃, the mixture of the waste SCR denitration catalyst and the coal powder can be converted into a high-temperature molten state, and the glassy hard slag is obtained after rapid cooling. According to the analysis result of scanning by an electron microscope and SEM, compared with the conventional pulverized coal boiler slag, the micro-morphology of the slag of the liquid-state slagging boiler is changed from a fine dispersion state of crystal grains to a sintering aggregation state of large crystal grains, which is beneficial to the wrapping and solidification of toxic substances in the waste SCR denitration catalyst, as shown in figures 2 and 3. Compared with the conventional pulverized coal boiler slag, the liquid-state slag-off boiler slag is gradually agglomerated and compacted from fine powder and is converted into hard particles with larger size, so that the volume reduction of the slag volume is more than 50%, as shown in fig. 4 and 5.

According to the experimental results of the toxicity leaching of the slag after the combustion of the sample, the limit requirements of 'hazardous waste identification standard leaching toxicity identification' (GB5085.3-2007) heavy metal leaching are met, and harmlessness of the waste SCR denitration catalyst is realized.

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.