A composite biomass denitration water agent for a new dry-process cement kiln, its usage method, and a denitration system

Abstract

The present invention relates to a composite biomass denitration water agent for a cement kiln, a method for using the same, and a denitration system. By taking advantage of the characteristics of the decomposition furnace atmosphere and spraying the biomass denitration water agent in the most suitable atmosphere and position, the present invention realizes economical, efficient, and environmentally friendly flue gas denitration. At the same time, it has the characteristics of less equipment investment, simple and convenient use, and green and renewable denitration agent, which will strongly promote the reduction of NOx emissions in the cement industry and environmental protection, and has important environmental, social, and economic significance.

Description

Technical Field

[0001] The present invention belongs to the field of flue gas denitrification in the cement industry, and particularly relates to a biomass denitrification aqueous agent for a new dry process cement kiln, its use method and a denitrification system. Background Art

[0002] In December 2013, the Ministry of Environmental Protection and the General Administration of Quality Supervision, Inspection and Quarantine jointly issued the "Emission Standard of Air Pollutants for Cement Industry" GB4915 - 2013 to replace the original standard GB4915 - 2004, stipulating that the NOx (calculated as NO2) emission concentration of existing and newly built cement plants shall not exceed 400 mg / m 3 , and the special emission limit for key areas is 150 mg / m 3 .

[0003] Currently, the most widely used flue gas denitrification technology in the cement industry is the selective non - catalytic reduction of NOx technology (SNCR). The SNCR method can use ammonia water, ammonia gas or urea as a reducing agent. The denitrification efficiency of this technology is relatively low (generally <60%), resulting in a relatively high cost of flue gas denitrification for cement enterprises and also unable to meet the increasingly strict NOx emission standards (unable to reduce the NOx emission concentration to 150 mg / m3). The selective catalytic reduction technology (SCR method) generally uses a titanium - based vanadium catalyst (V2O5 - WO3 / TiO2). The SCR method can also use ammonia water, ammonia gas or urea as a reducing agent. The SCR method has a relatively high active temperature window (320 - 420 °C), and the SCR device needs to be installed before the kiln tail dust collector. However, the dust and SO2 concentrations in the flue gas at this location are relatively high, which easily causes catalyst poisoning and reduces the service life of the catalyst. In the SCR and SNCR denitrification technologies, the use efficiency of ammonia water is 60 - 80%. When the temperature is too high, ammonia and oxygen react to form NOx, and when the temperature is too low, the reduction rate of NOx is too low, and ammonia escape in the flue gas is serious. In addition, ammonia water is also a high - energy - consumption and high - pollution product. Therefore, there is an urgent need to develop a low - cost and high - efficiency flue gas denitrification technology suitable for the cement industry.

[0004] In addition, there is a technical specification GB 51045 - 2014 "Technical Specification for Denitrification Engineering in Cement Plants" in the cement industry for denitrification technology, which is specifically promulgated for the denitrification process. Based on the particularities of the denitrification reaction principle, the source of target pollutants, denitrification reaction conditions (such as denitrification reaction temperature), reaction environment, selection of denitrifying agents, etc. of the denitrification technology itself, those skilled in the art generally believe that there are obvious differences between denitrification technology and other environmental protection technologies such as desulfurization processes, and thus will not directly borrow technologies from other fields to solve problems in the denitrification process.

[0005] Generally speaking, the denitration process in the prior art has low efficiency and poor denitration effect, and the denitrating agent has problems of high cost and serious pollution. Moreover, those skilled in the art are also easily restricted by the technical field during the research and development of denitration technology, resulting in the absence of a satisfactory dry denitration technology for cement kilns that is economical, environmentally friendly and efficient.

[0006] On the other hand, the biomass resources on the earth are extremely large and can be continuously regenerated. Its main constituent elements C, H, and O are also the three most frequently transformed or used elements in modern chemical industry. If biomass resources can be efficiently converted into starting materials that can be used in the chemical industry, biomass resources will play a more important role in the human resource structure. Therefore, preparing various chemicals from biomass has become an important means for the efficient utilization of biomass resources. Countries around the world have regarded the development of biomass chemical technology as an important strategic deployment and invested a large amount of manpower and material resources in research and development. From the perspective of the oxidation-reduction of the reaction, the C and H elements contained in biomass have reducibility. How to apply them as nitrogen oxide reductants in the cement industry to replace the currently used high-energy reductant ammonia water is an important research goal with broad prospects and significant economic and social benefits.

[0007] However, the applicant has found that by carefully selecting the type and addition position of the denitrating agent, the efficiency of the denitration process can be significantly improved, the denitration effect can be improved, and the denitration cost can be reduced. Summary of the Invention

[0008] In order to reduce the NOx emissions in the flue gas of cement kilns (especially new dry process cement kilns), the applicant of the present invention provides a biomass denitration aqueous agent for cement kilns, its use method and a denitration system according to the characteristics of the cement production process (especially the structure and atmosphere characteristics of the decomposition furnace). In particular, in this application, by spraying the biomass denitration aqueous agent in the most suitable atmosphere and position, economical, efficient and environmentally friendly flue gas denitration is achieved.

[0009] The new dry process cement production method is a modern cement production method with suspension preheating and precalcining technology as the core, and it is the commonly used cement production method in China. The device for the new dry process cement production method usually includes at least components such as a rotary kiln, a decomposition furnace and a cyclone.

[0010] In one aspect, the technical solution adopted by the present invention is as follows: A biomass denitration aqueous agent is sprayed and added at a position between the tail end of the rotary kiln and the tail end of the tertiary air duct (preferably the kiln tail flue gas chamber) (position 1). Preferably, the technical solution of the present invention further includes spraying and adding another part of the biomass denitration aqueous agent at a position between the outlet of the decomposition furnace and the inlet of the lowest-stage cyclone (position 3). Further preferably, the position between the outlet of the decomposition furnace and the inlet of the lowest-stage cyclone is the downward part of the connecting air duct from the outlet of the decomposition furnace to the lowest-stage cyclone. More preferably, the position between the outlet of the decomposition furnace and the inlet of the lowest-stage cyclone is the inlet part of the lowest-stage cyclone.

[0011] It is believed that at the said position, the biomass in the biomass denitration aqueous agent reacts with water to generate a mixture containing hydrocarbons such as CO, CH4, H2, HCN, etc. This mixture can rapidly and efficiently reduce NOx to N2.

[0012] [[ID=`6]]As used in this application, the term "spraying and adding" independently refers to an addition means of adding the denitration aqueous agent to a desired position by pressure in the presence or absence of a carrier (such as water or a carrier gas, such as air). Other means known to those skilled in the art can also be used to add the denitration aqueous agent to the desired position, as long as the other means can add the denitration aqueous agent to the desired position. In this application, "spraying and adding", "putting in", "spraying in", and "adding" can be used interchangeably.

[0013] By using the above-mentioned spraying and adding positions, especially the combination of the denitration aqueous agent and the spraying and adding position, this application can significantly improve the efficiency of the denitration process, improve the denitration effect, and reduce the denitration cost. The applicant has found that excellent denitration effects can be obtained by using the biomass denitration aqueous agent at the said position, and the achieved denitration efficiency is significantly higher than that in the prior art.

[0014] In addition, the present invention also relates to a biomass denitration system for a cement kiln, which includes a biomass denitration aqueous agent and an aqueous agent spraying and adding device. The biomass denitration aqueous agent is as described herein; the aqueous agent spraying and adding device includes an aqueous agent storage tank, a circulation pump, and an aqueous agent spray gun, and the aqueous agent spray gun is installed at a position between the tail end of the rotary kiln and the tail end of the tertiary air duct. The aqueous agent spraying and adding device preferably further includes a water jet pump, a flow meter, a valve, an aqueous agent pipeline, and a compressed air pipeline. Preferably, the technical solution of the present invention further includes another aqueous agent spray gun located at a position between the outlet of the decomposition furnace and the inlet of the lowest-stage cyclone. Further preferably, the position between the outlet of the decomposition furnace and the inlet of the lowest-stage cyclone is the downward part of the connecting air duct from the outlet of the decomposition furnace to the lowest-stage cyclone. More preferably, the position between the outlet of the decomposition furnace and the inlet of the lowest-stage cyclone is the inlet part of the lowest-stage cyclone.

[0015] The reactions that may be involved in the denitration process are as follows:

[0016] (1) The biomass denitration water agent decomposes or reacts with carbon, releasing hydrocarbons:

[0017] 2C + O2 → 2CO

[0018] C + H2O → CO + H2

[0019] CxHyOz → (x - z)C + z CO + y / 2H2

[0020] (2) The hydrocarbons reduce NOx to nitrogen:

[0021] 2NOx + (x + 1)H2 → 2NH + x H2O

[0022] NH + NH → N2 + H2

[0023] 2H2 + 2NO → N2 + 2H2O

[0024] 2NOx + x C → N2 + x CO2

[0025] 2NOx + 2x C → N2 + 2x CO

[0026] 2NOx + 2x CO → N2 + 2x CO2

[0027] The reaction principle of the denitration process is complex, and various reaction processes are intertwined. The reactions occurring under different conditions and environments can also change at any time. Therefore, it is not easy to obtain a denitration agent that can achieve excellent denitration effects under various working conditions.

[0028] Through years of theoretical and practical research, this patent innovatively proposes a technical solution for a biomass denitration aqueous agent. The biomass denitration aqueous agent includes 40-80% by weight of water; 20-60% by weight of a liquid biomass pyrolysis liquid; and 10-40% by weight of a C1-C10 monohydric alcohol or polyhydric alcohol. In one embodiment, the water accounts for 40, 45, 50, 55, 60, 65, 70, 75, 80% by weight of the biomass denitration aqueous agent. In one embodiment, the liquid biomass pyrolysis liquid accounts for 20, 25, 30, 35, 40, 45, 50, 55, 60% by weight of the biomass denitration aqueous agent. In one embodiment, the C1-C10 monohydric alcohol or polyhydric alcohol accounts for 10, 15, 20, 25, 30, 35, 40% by weight of the biomass denitration aqueous agent. In a preferred embodiment, the biomass denitration aqueous agent consists of 40-80% by weight of water; 20-60% by weight of a liquid biomass pyrolysis liquid; and 10-40% by weight of a C1-C10 monohydric alcohol or polyhydric alcohol, and the sum of each component is 100%. The above components are mixed evenly in proportion to prepare the biomass denitration aqueous agent. The biomass denitration aqueous agent is a mixture of water, a C1-C10 monohydric or polyhydric alcohol solvent, and a liquid biomass pyrolysis liquid.

[0029] The liquid biomass pyrolysis liquid in the biomass denitration water agent is a liquid substance containing C4-C17 liquid hydrocarbons, or C4-C17 hydrocarbon-oxygen substances or a mixture thereof obtained during the pyrolysis process of biomass materials under anoxic and heating conditions (preferably 400-800 °C), and it may contain a certain amount of water. The biomass materials include any non-fossilized plant materials, animal materials or microbial materials (preferably plant materials). The biomass materials include agricultural and forestry by-products and / or industrial processing organic wastes; preferably, the agricultural and forestry by-products include: tree branches, leaves, bark, wood, grass, corncobs, straw, rice husks, fruit husks, shrubs and vines, and the industrial organic processing wastes include: sugarcane residues, wood wastes (such as wood chips, wood processing wastes and forest areas) and grass wastes. The pyrolysis (also known as thermal decomposition or cracking) of biomass generally refers to the process in which biomass is heated and raised in temperature under an anaerobic or low-oxygen environment, causing molecular decomposition, and then producing coke, condensable liquids and gas products, which is an important utilization form of biomass energy. The method of biomass pyrolysis is known in the art. In one embodiment, the C4-C17 liquid hydrocarbons or a mixture of C4-C17 hydrocarbon-oxygen substances obtained by the thermal pyrolysis of tree branches and wood chips under anoxic conditions are used in this application. As mentioned above, those skilled in the art are aware that other suitable biomass materials, such as various agricultural and forestry by-products (including straw, rice husks, corncobs, bean husks, tree branches, wood, etc.), industrial processing organic wastes (such as sugarcane residues in the sugar industry, wood chips and scraps in wood processing, etc.) can also obtain the liquid biomass pyrolysis liquid described in this case under similar conditions.

[0030] The C1-C10 monohydric alcohols or polyhydric alcohols shown include, but are not limited to: methanol, ethanol, propanol, isopropanol, glycerol, n-butanol, isobutanol, tert-butanol, etc.

[0031] Regarding the injection position of the biomass denitration water agent:

[0032] The new dry-process cement kiln production line is very large in volume, and nitrogen-containing pollutants are generated in multiple equipment or production links. Therefore, there are many choices and combinations for the position to add the denitration agent. However, the inventor has found through research that the addition position of the denitration agent has a significant impact on the final effect. When adding the denitration agent at the addition positions known in the prior art or in other devices other than this invention, the denitration effect cannot achieve the expected technical effect. The inventor has creatively proposed the following addition positions through research.

[0033] In this application, the biomass denitration water agent can be used in the following manner (as shown in the attached Figure 2 specification):

[0034] The biomass denitration aqueous agent is sprayed at the position between the tail end of the rotary kiln and the tail end of the tertiary air duct (preferably the kiln tail flue gas chamber).

[0035] In a preferred embodiment, it further includes spraying another part of the biomass denitration aqueous agent at the position between the outlet of the decomposition furnace and the inlet of the lowest-stage cyclone. Further preferably, the position between the outlet of the decomposition furnace and the inlet of the lowest-stage cyclone is the downward part of the connecting air duct between the outlet of the decomposition furnace and the lowest-stage cyclone. More preferably, the position between the outlet of the decomposition furnace and the inlet of the lowest-stage cyclone is the inlet part of the lowest-stage cyclone. The lowest-stage cyclone refers to the lowest-stage cyclone counted from bottom to top among one or more stages of cyclones. For example, the lowest-stage cyclone of a five-stage cyclone is the C5 cyclone, and the lowest-stage cyclone of a six-stage cyclone is the C6 cyclone, and so on. The decomposition furnace and the lowest-stage cyclone are connected by a connecting air duct. The connecting air duct can be of any shape determined according to the actual situation. Generally, the connecting air duct includes an upward part and a downward part. The upward part of the connecting air duct connects the outlet of the decomposition furnace and is used to discharge the gas. The downward part of the connecting air duct connects the upward part and the inlet of the lowest-stage cyclone and is used to introduce the gas into the cyclone. The upward part and the downward part are intended to indicate that the gas first flows through the upward part and then through the downward part, and are not intended to limit the gas flow direction in other meanings. In one embodiment, the connecting air duct is curved and has a shape with the middle part higher than one or both of the two ends, such as an inverted U shape or an n shape. At this time, the upward part also refers to the part where the gas travels upward, and the downward part also refers to the part where the gas travels downward. The outlet of the decomposition furnace described herein is also called the burnout zone.

[0036] The "position" described herein refers to the position where the biomass denitration aqueous agent is sprayed, and it can be used interchangeably with the "spraying position".

[0037] In an embodiment of the present invention, a two-fluid spray gun is used to atomize the denitration aqueous agent into droplets with a size of <10 μm, and it is sprayed from the said position.

[0038] In one embodiment, multiple / layers of spray guns can be used at the spraying position in this application. Through the layout of multiple layers of spray guns (preferably staggering the spray guns of each layer by a certain angle), a full coverage and uniform spraying are formed, and the utilization efficiency of the biomass flue gas denitration aqueous agent is improved.

[0039] The dosage of the biomass denitration water agent is 0.01 to 1.0% by weight of the cement raw material feed amount (for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95% by weight). The flue gas denitration efficiency achieved by this application can reach over 90%, such as 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%.

[0040] In this invention, the denitration efficiency = (the background concentration before denitration - the emission concentration after denitration) / the background concentration before denitration * 100%.

[0041] In addition, by selecting the above types of denitration agents and their addition positions, and using metering feeders and flow control devices in the biomass denitration system, etc., the spraying amount of the biomass denitration water agent can be adjusted in real time according to the NOx content in the flue gas, so as to achieve continuous and precise control of the emission index. If the water agent is added at other positions, such as the front end of the rotary kiln, it is usually impossible to achieve real-time precise control of the emission index.

[0042] In summary, in this invention, the spraying position of the biomass denitration water agent is extremely particular (the optimal spraying position is determined based on thousands of hours of industrial online tests), and the spraying amount of the biomass denitration water agent can be automatically controlled and adjusted according to the NOx content in the flue gas, realizing economic, environmental and efficient flue gas denitration. This invention is essentially a technological innovation based on the existing denitration technology. By introducing more hydrocarbon compounds through the biomass water agent and performing multiple mixtures with the material to be treated under suitable temperature and atmosphere environments, the removal rate and efficiency of NOx are significantly improved. More importantly, this invention innovatively uses the biomass-derived water agent as the main component of the denitration agent, introducing the concept of comprehensive treatment of waste utilization in the cement environmental protection industry. The main component of the denitration agent used, the biomass denitration water agent, is prepared by carbonization and pyrolysis of biomass with wide sources. The raw materials are easily available, green, environmentally friendly and renewable. At the same time, the equipment investment is small, the process is simple and reliable, it does not affect the quality of the clinker, the denitration efficiency is high, and the cost is low. It has incomparable technical, economic and environmental advantages compared with SCR and SNCR, and has great application prospects and potential in the field of flue gas denitration in the cement industry.

[0043] Unless otherwise specified, the percentages, ratios, rates, contents or parts described in this application are by weight. The concentration described in this application is the weight concentration.

[0044] The temperature unit "degree" described in this application refers to Celsius.

[0045] The denitrification aqueous agent described in this application is a denitrification aqueous agent for removing flue gas. Therefore, the term "biomass denitrification aqueous agent" in this application can also be referred to as "biomass flue gas denitrification aqueous agent", and the two can also be used interchangeably. In this article, the denitrifying agent refers to the denitrification aqueous agent and / or the denitrification powder. Description of the Drawings

[0046] Figure 1 : An embodiment showing positions 1, 2, and 3, in which the relative positions of air, clinker, cooler, and fuel are also shown.

[0047] Figure 2 : An embodiment of adding the denitrifying agent from position 1.

[0048] Figure 3 : An embodiment of adding the denitrifying agent from positions 1 and 3

[0049] Figure 4 : An exemplary arrangement of spray guns.

[0050] Figure 5 : An exemplary aqueous agent adding device.

[0051] Description of the Reference Numerals

[0052] 1. Position 1

[0053] 2. Position 2

[0054] 3. Position 3

[0055] 4. Rotary kiln

[0056] 5. Tail gas chamber of the kiln

[0057] 6. Front section of the precalciner

[0058] 7. Middle section of the precalciner

[0059] 8. Rear section of the precalciner

[0060] 9. Upward part of the connecting air duct

[0061] 10. Downward part of the connecting air duct

[0062] 11. C5 cyclone

[0063] 12. Cyclone connecting air duct

[0064] 13. C4 cyclone

[0065] 14. C3 cyclone

[0066] 15. C2 cyclone

[0067] 16. C1 cyclone

[0068] 17. Tertiary air duct

[0069] 31. Biomass denitrification aqueous agent storage tank

[0070] 32. Aqueous agent output pump

[0071] 33. Liquid flowmeter

[0072] 34. Liquid valve

[0073] 35. Liquid check valve

[0074] 36. Liquid delivery pipeline

[0075] 37. Liquid flowmeter

[0076] 38. Liquid valve

[0077] 39. Liquid check valve

[0078] 40. Air compressor

[0079] 41. Gas flowmeter

[0080] 42. Gas valve

[0081] 43. Gas delivery pipeline

[0082] 101. Biomass denitrification aqueous agent storage equipment

[0083] 102. Aqueous agent unloading and circulation system

[0084] 103. Aqueous agent unloading and circulation system

[0085] 104. Liquid level measuring equipment

[0086] 105. Pump delivery equipment

[0087] 106. Flow measurement equipment

[0088] 107. Pressure detection equipment

[0089] 108. Atomizing spray gun equipment

[0090] 109. Compressed air equipment

[0091] 301. Pump delivery equipment

[0092] 302. Flow measurement equipment

[0093] 303. Pressure detection equipment

[0094] 304. Atomizing spray gun equipment

[0095] 305. Compressed air equipment Specific implementation manners

[0096] To better understand the present invention, the content of the present invention will be further elaborated below in conjunction with embodiments. However, the content of the present invention is not limited to the following embodiments. The experimental operations described in the following embodiments are all conventional operations unless otherwise specified; the reagents and materials, unless otherwise specified, can be obtained from commercial channels. The cyclone used in the embodiments and comparative examples is a five-stage cyclone, so the C5 cyclone is the lowest-stage cyclone.

[0097] Example 1:

[0098] The mass percentages of the components in the biomass denitration aqueous agent are as follows: water content 70%, biomass pyrolysis liquid 15%, and methanol 15%.

[0099] This example is used on a 5000 t / d new dry-process cement production line located in Guangdong. The actual monitored NOx concentration in the flue gas is 850 mg / m 3 . Using the existing technology (biomass composite denitration) spraying system, the biomass denitration aqueous agent is sprayed at the kiln tail smoke chamber (location 1), sprayed through 4 spray guns arranged at intervals of 90° in the same plane, and the denitration aqueous agent is atomized into droplets smaller than 10 μm by using high-pressure air. The spraying amount of the biomass denitration aqueous agent is 1000 L / h (about 0.3% of the cement raw material feeding amount). After 10 minutes, the NOx concentration in the flue gas can be stabilized at about 130 mg / m 3 , and the denitration efficiency of the cement kiln flue gas is 85%.

[0100] Example 2:

[0101] The mass percentages of the components in the biomass denitration aqueous agent are as follows: water content 60%, biomass pyrolysis liquid 20%, and glycerol 20%.

[0102] This example is used on a 5000 t / d new dry-process cement production line located in Guangdong. The actual monitored NOx concentration in the flue gas is 840 mg / m 3 . Using the existing technology (biomass composite denitration) spraying system, the biomass denitration aqueous agent is sprayed at the kiln tail smoke chamber (location 1), sprayed through 4 spray guns arranged at intervals of 90° in the same plane, and the denitration aqueous agent is atomized into droplets smaller than 10 μm by using high-pressure air. The spraying amount of the biomass denitration aqueous agent is 1200 L / h (about 0.35% of the cement raw material feeding amount). After 10 minutes, the NOx concentration in the flue gas can be stabilized at about 120 mg / m 3 , and the denitration efficiency of the cement kiln flue gas is 86%.

[0103] Example 3:

[0104] The mass percentages of the components in the biomass denitration aqueous agent are as follows: water content 60%, biomass pyrolysis liquid 20%, and ethylene glycol 20%.

[0105] This example is used in a 5000t / d new dry-process cement production line located in Guangdong. The actual monitored NOx concentration in the flue gas is 880mg / m 3 . Using the existing technology (biomass composite denitration) spraying system, biomass denitration aqueous agent is sprayed at the kiln tail flue chamber (position 1). It is sprayed through 4 spray guns arranged at 90° intervals in the same plane, and the denitration aqueous agent is atomized into droplets smaller than 10μm by high-pressure air. The spraying amount of the biomass denitration aqueous agent is 900L / h (about 0.35% of the cement raw material feeding amount). After 10 minutes, the NOx concentration in the flue gas can be stabilized at about 130mg / m 3 , and the denitration efficiency of the cement kiln flue gas is 85%.

[0106] Example 4:

[0107] The mass percentages of each component in the biomass denitration aqueous agent are: water content 50%, biomass pyrolysis liquid 20%, and methanol 30%.

[0108] This example is used in a 5000t / d new dry-process cement production line located in Anhui. The actual monitored NOx concentration in the flue gas is 870mg / m 3 . Using the system described in this application, only one biomass denitration aqueous agent storage tank is placed on the ground. Biomass denitration aqueous agent is sprayed at the kiln tail flue chamber (position 1) through a multistage centrifugal pump and an aqueous agent spray gun, and another part of the biomass denitration aqueous agent is sprayed at the inlet part of the C5 cyclone duct (position 3) through a multistage centrifugal pump and an aqueous agent spray gun. The biomass denitration aqueous agent is sprayed through 4 spray guns arranged at 90° intervals in the same plane at position 1, and the biomass denitration aqueous agent is sprayed through 8 spray guns arranged at 90° intervals in two layers at position 3. The denitration aqueous agent is atomized into droplets smaller than 10μm by high-pressure air. The spraying amount of the biomass denitration aqueous agent is 1500L / h (about 0.4% of the cement raw material feeding amount). The spraying ratio of position 1 to position 3 is 3:2, where the spraying amount at position 1 is about 900L / h and the spraying amount at position 3 is about 600L / h. After 10 minutes, the NOx concentration in the flue gas can be stabilized at 70mg / m 3 or lower, and the minimum can reach 62mg / m 3 , and the denitration efficiency of the cement kiln flue gas reaches more than 92%.

[0109] Example 5: Preparation of biomass denitration aqueous agent

[0110] Collect about 5 tons of tree branches, heat them in a gasifier under air isolation to 500 °C, and obtain about 3 tons of biomass pyrolysis liquid. After testing, it contains hydrocarbons and carbon-hydroxyl compounds with C4 - C17. The pyrolysis liquid has a relatively high viscosity. Add 14 tons of water and 3 tons of methanol, and use a high-speed shearing and stirring device at a speed of 20,000 revolutions per minute to stir for about 15 minutes to prepare 20 tons of substantially uniform biomass denitration water agent for Example 1. Use different amounts of the aforementioned biomass pyrolysis liquid, water, and methanol to prepare the biomass denitration water agent for Example 4.

[0111] Example 6: Preparation of biomass denitration water agent

[0112] Collect about 8 tons of sugarcane residues, heat them in a gasifier under air isolation to 450 °C, and obtain about 5 tons of biomass pyrolysis liquid. After testing, it contains hydrocarbons and carbon-hydroxyl compounds with C4 - C17. The pyrolysis liquid has an extremely high viscosity. Add 15 tons of water and 5 tons of glycerol, and use a high-speed shearing and stirring device at a speed of 20,000 revolutions per minute to stir for about 15 minutes to prepare 25 tons of substantially uniform biomass denitration water agent for Example 2. Use different amounts of the aforementioned biomass pyrolysis liquid, water, and ethylene glycol to prepare the biomass denitration water agent for Example 3.

[0113] Comparative Example 1:

[0114] This comparative example is used on a 5000t / d new dry-process cement production line located in Guangdong. The actual monitored NOx concentration in the flue gas is 800mg / m 3 . Use the original technology (SNCR selective non-catalytic reduction) spraying system, and spray 900L / h (about 0.25% of the raw meal feeding amount) of 20% ammonia water through a water agent spray gun at the outlet of the decomposition furnace (position 2). Spray it through 8 spray guns arranged at intervals of 45° on the same plane, and use high-pressure air to atomize the denitration water agent into droplets smaller than <10μm. After 10 minutes, the NOx concentration in the flue gas can be stabilized at about 350mg / m 3 , and the flue gas denitration efficiency is only 56%.

[0115] Comparative Example 2:

[0116] This comparative example is used on a 5000t / d new dry-process cement production line in Anhui. The actual monitored NOx concentration in the flue gas is 900mg / m 3 . At the kiln tail smoke chamber (position 1), use an air pump to spray 3 - 5t / h (1 - 1.5% of the raw meal feeding amount) of pulverized coal. After 10 minutes, the NOx concentration in the flue gas can be stabilized at about 750mg / m 3 , and the flue gas denitration efficiency is only 16.7%.

[0117] Comparative Example 3:

[0118] This comparative example is used in a 5000 t / d new dry-process cement production line located in Guangdong, and the actual monitored NOx concentration in the flue gas is 850 mg / m 3 or so. Using the existing technology (biomass composite denitration) spraying system, 1000 L / h (about 0.25% of the raw meal feeding amount) of water is sprayed through a water-based spray gun at the kiln tail smoke chamber (position 1), and is sprayed through 4 spray guns arranged at 90° intervals on the same plane. High-pressure air is used to atomize the denitration aqueous agent into droplets smaller than 10 μm. After 10 minutes, the NOx concentration in the flue gas still remains stable at about 830 - 850 mg / m 3 or so, and there is almost no denitration effect.

[0119] Comparative Example 4:

[0120] This comparative example is used in a 5000 t / d new dry-process cement production line located in Guangdong, and the actual monitored NOx concentration in the flue gas is 800 mg / m 3 or so. Using the existing technology (biomass composite denitration) spraying system, 1000 L / h (about 0.25% of the raw meal feeding amount) of 20% concentration ammonia water is sprayed through a water-based spray gun at the kiln tail smoke chamber (position 1), and is sprayed through 4 spray guns arranged at 90° intervals on the same plane. High-pressure air is used to atomize the denitration aqueous agent into droplets smaller than 10 μm. After 10 minutes, the NOx concentration in the flue gas still remains stable at about 600 mg / m 3 or so, and the flue gas denitration efficiency is only 25%.

[0121] Table 1: Summary Table of Denitration Efficiency

[0122]

[0123] It can be seen from the above examples and comparative examples that, firstly, the biomass denitration aqueous agent used in this patent has a higher denitration efficiency compared to traditional pulverized coal and ammonia water denitration agents; secondly, the denitration position selected in this patent has a more excellent denitration effect compared to other positions. If the two are combined, an economic, environmentally friendly, and efficient denitration technical solution can be further obtained, and the technical effect of this solution cannot be achieved by all existing technologies currently.

[0124] The above is only a preferred embodiment of the present invention, and does not impose any form of limitation on the invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in this field can make some modifications or equivalent changes within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A novel dry-process cement kiln biomass denitrification agent, the biomass denitrification agent comprising the following components: 40-80 wt% water; 20-60 wt% liquid biomass pyrolysis liquid; and 10-40 wt% C1-C10 monohydric alcohol or polyol; The liquid biomass cracking liquid in the biomass denitrification agent is a liquid substance containing C4-C17 liquid hydrocarbons, or C4-C17 hydrocarbon-oxygen substances or a mixture thereof obtained during the cracking process of biomass materials under anoxic and heating conditions.

2. The novel dry-process cement kiln biomass denitrification agent according to claim 1, wherein the biomass material comprises any non-fossilized plant material, animal material or microbial material.

3. The biomass denitrification agent for cement kilns according to claim 1 or 2, wherein the biomass material comprises agricultural and forestry byproducts and / or industrial processing organic waste; the agricultural and forestry byproducts comprise: Branches, leaves, bark, wood, grass, corn cobs, straw, rice husks, fruit shells, shrubs and vines, or the industrial processing organic waste includes: bagasse, wood waste and grass waste.

4. The novel dry-process biomass denitrification agent for cement kilns according to claim 1, wherein the heating condition includes heating to 400-800°C.

5. The novel dry-process biomass denitrification agent for cement kilns according to claim 1, wherein the C1-C10 monohydric alcohol or polyhydric alcohol comprises methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, benzyl alcohol, ethylene glycol, glycerol, or a mixture of two or more thereof.

6. The method for using the novel dry process cement kiln biomass denitrification agent according to claim 1, characterized in that The biomass denitrification agent is used in the following manner: Spray biomass denitrification agent between the tail end of the rotary kiln and the tail end of the tertiary air duct.

7. The method according to claim 6, wherein The position between the tail end of the rotary kiln and the tail end of the tertiary air duct is the kiln tail smoke chamber.

8. The method according to claim 6 or 7, further comprising spraying another portion of the biomass denitrification agent at a position between the decomposition furnace outlet and the lowest cyclone inlet.

9. The method according to claim 8, wherein the position between the outlet of the decomposition furnace and the inlet of the lowest cyclone is the downward portion of the air duct connecting the outlet of the decomposition furnace to the lowest cyclone.

10. The method according to claim 8, wherein the position between the outlet of the decomposition furnace and the inlet of the lowest stage cyclone is the inlet portion of the lowest stage cyclone.

11. A novel dry-process biomass denitrification system for cement kilns, comprising a biomass denitrification agent and an agent spraying device, wherein the biomass denitrification agent is as described in any one of claims 1 to 5; the agent spraying device comprises an agent storage tank, a circulation pump, and an agent spray gun, wherein the agent spray gun is installed at a position between the rear end of the rotary kiln and the rear end of the tertiary air duct.

12. The novel dry process biomass denitrification system for cement kilns according to claim 11, characterized in that The water agent spraying device also includes a jet pump, a flow meter, a valve, a water agent pipeline, and a compressed air pipeline.

13. The system according to any one of claims 11 to 12, wherein the position between the rear end of the rotary kiln and the rear end of the tertiary air duct is a kiln tail smoke chamber.

14. The system of claim 11, further comprising an additional water spray gun located between the outlet of the decomposition furnace and the inlet of the lowest stage cyclone.

15. The system according to claim 14, wherein the position between the outlet of the decomposition furnace and the inlet of the lowest stage cyclone is the downward portion of the air duct connecting the outlet of the decomposition furnace to the lowest stage cyclone.

16. The system according to claim 14, wherein the position between the outlet of the decomposition furnace and the inlet of the lowest stage cyclone is the inlet portion of the lowest stage cyclone.

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