A novel composite biomass denitrification powder for dry-process cement kiln, its use method and denitrification system

Abstract

The present invention relates to a composite biomass denitrification powder for cement kiln, a method for using the same and a denitrification system. The present invention utilizes the characteristics of the decomposition furnace atmosphere, sprays the biomass denitrification powder in the most suitable atmosphere and position, and realizes economical, efficient and environmentally friendly flue gas denitrification. The invention also has the characteristics of low equipment investment, simple and convenient use, and green and renewable denitrification agent, which will effectively promote NOx emission reduction and environmental protection in the cement industry, and has important environmental, social and economic significance.

Description

Technical Field

[0001] The invention belongs to the field of flue gas denitration in cement industry, and in particular relates to a novel biomass denitration powder for dry-process cement kilns, a use method thereof and a denitration system. Background Art

[0002] The emission of nitrogen oxides (NOx) from the cement industry has become the third largest pollution source after thermal power generation and automobile exhaust. In December 2013, the Ministry of Environmental Protection and the General Administration of Quality Supervision, Inspection and Quarantine jointly issued the "Emission Standards for Air Pollutants from the Cement Industry".

[0003] GB4915-2013 replaces the original standard GB4915-2004 and stipulates that the NOx (in terms of NO 2 The emission concentration shall not exceed 400mg / m 3 The special emission limit for key areas is 150mg / m 3 .

[0004] At present, 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 low (generally <60%), resulting in high flue gas denitrification costs for cement companies and the inability to meet increasingly stringent NOx emission standards (unable to reduce NOx emission concentration to 150mg / m3). Selective catalytic reduction technology (SCR method) generally uses titanium-based vanadium catalysts (V 2 O 5 -WO 3 / TiO 2 ). The SCR method can also use ammonia water, ammonia gas or urea as a reducing agent. The SCR method has a high active temperature window (320-420°C), and the SCR device needs to be installed before the dust collector at the end of the kiln. However, the dust and SO in the flue gas at this location 2 The concentration is high, which can easily cause catalyst poisoning and reduce the service life of the catalyst. The efficiency of ammonia water in SCR and SNCR denitrification technology is 60-80%. When the temperature is too high, ammonia and oxygen react to generate NOx. When the temperature is too low, the NOx reduction rate 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, it is urgent to develop low-cost and high-efficiency flue gas denitrification technology suitable for the cement industry.

[0005] In addition, the denitrification technology in the cement industry has a technical specification GB 51045-2014 "Technical Specification for Denitrification Engineering in Cement Plants", which is specially issued for the denitrification process. Based on the particularity of the denitrification reaction principle, target pollutant source, denitrification reaction conditions (such as denitrification reaction temperature), reaction environment, and selection of denitrification agents of the denitrification technology itself, technicians in this field generally believe that there are obvious differences between denitrification technology and other environmental protection technologies such as desulfurization technology, and will not directly borrow technologies from other fields to solve problems in the denitrification process.

[0006] In general, the efficiency of the denitrification process in the existing technology is low, the denitrification effect is not good, and the denitrification agent has the problems of high cost and serious pollution; and the technical personnel in this field are also easily restricted by the technical field when developing the denitrification technology, resulting in the lack of a satisfactory economic, environmentally friendly and efficient dry cement kiln denitrification technology.

[0007] On the other hand, the amount of biomass resources on the earth is very large and can be continuously regenerated. Its main components, C, H, and O, are also the three most frequently converted or used elements in the modern chemical industry. If biomass resources can be efficiently converted into starting materials that can be used by the chemical industry, biomass resources will play a more important role in the human resource structure. Therefore, the preparation of various chemicals from biomass has become an important means of 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 lot of manpower and material resources in research and development. From the perspective of redox reaction, the C and H elements contained in biomass are reducing. How to apply them to the cement industry as a nitrogen oxide reducing agent to replace the currently used high-energy reducing agent ammonia is an important research goal with broad prospects and significant economic and social benefits.

[0008] However, the applicant has found that by carefully selecting the type and addition location of the denitrification agent, the efficiency of the denitrification process can be significantly improved, the denitrification effect can be improved, and the denitrification cost can be reduced. Summary of the invention

[0009] In order to reduce the flue gas NOx emission of cement kilns (especially new dry process cement kilns), the applicant of the present invention provides a biomass denitrification powder for cement kilns and its use method and denitrification system according to the characteristics of cement production process (especially the structure and atmosphere characteristics of decomposition furnace). In particular, the present application realizes economical, efficient and environmentally friendly flue gas denitrification by spraying the biomass denitrification powder in the most suitable atmosphere and position.

[0010] The new dry process cement production method is a modern cement production method with suspension preheating and off-kiln decomposition technology as the core, and is a cement production method widely used in my country. The equipment used for the new dry process cement production method usually includes at least a rotary kiln, a decomposition furnace and a cyclone.

[0011] In one aspect, the technical solution adopted by the present invention is: spraying biomass denitrification powder at a position (preferably the upward part of the air duct connecting the decomposition furnace outlet to the lowest cyclone, more preferably the decomposition furnace outlet part) (position 2) between the middle and rear section of the decomposition furnace and the entrance of the lowest cyclone (the fifth-stage preheater is the C5 cyclone, the sixth-stage preheater is the C6 cyclone, and so on).

[0012] It is believed that at the above position, the biomass in the biomass denitrification powder reacts with water to generate CO, CH 4 , H 2 , HCN and other hydrocarbons. This mixture can quickly and efficiently reduce most of the NOx to N 2 .

[0013] The spraying described in the present application refers independently to the addition means of adding the denitrification agent to the desired position by pressure in the presence or absence of a carrier (e.g., water or a carrier gas, such as air) at each occurrence. Other means known to those skilled in the art can also be used to add the denitrification agent to the desired position, as long as the other means can add the denitrification agent to the desired position. In the present application, "spraying", "putting in", "spraying" and "adding" can be used interchangeably.

[0014] The present application can significantly improve the efficiency of the denitrification process, improve the denitrification effect, and reduce the denitrification cost by using the above-mentioned spraying positions, especially the combination of the denitrification water agent and the spraying position. The applicant has found that by using the biomass denitrification water agent at the above position, an excellent denitrification effect can be obtained, and the denitrification efficiency achieved is significantly higher than the denitrification efficiency in the prior art.

[0015] In addition, the present invention also relates to a biomass denitrification system for a cement kiln, which includes a biomass denitrification powder and a powder spraying device, wherein the biomass denitrification powder is as described herein; the powder spraying device includes a powder storage bin, a fan, and a powder spray gun, and the powder spray gun is installed at a position between the rear section of the decomposition furnace and the entrance of the lowest level cyclone.

[0016] In a preferred embodiment, in addition to the powder storage bin, the blower and the powder spray gun, the powder spraying device also includes a metering feeder, a pneumatic conveying pump, a Roots blower, a powder pipeline, a compressed air pipeline, and a valve.

[0017] The reactions that may be involved in the denitrification process are as follows:

[0018] (1) Biomass denitrification agent decomposes or reacts with carbon to release hydrocarbons:

[0019] 2C+O 2 →2CO

[0020] C+H 2 O→CO+H 2

[0021] CxHyOz→(xz)C+z CO+y / 2H 2

[0022] (2) Hydrocarbons reduce NOx to nitrogen:

[0023] 2NOx+(x+1)H 2 →2NH+xH 2 O

[0024] NH+NH→N 2 +H 2

[0025] 2H 2 +2NO→N 2 +2H 2 O

[0026] 2NOx+x C→N 2 +x CO 2

[0027] 2NOx+2x C→N 2 +2x CO

[0028] 2NOx+2xCO→N 2 +2x CO 2

[0029] The reaction principle of the denitrification process is complex, various reaction processes are intertwined, and the reactions occurring under different conditions and environments may change at any time. Therefore, it is not easy to obtain a denitrification agent that can achieve excellent denitrification effects under various working conditions.

[0030] Through years of theoretical and practical research, this patent innovatively proposes a technical solution for biomass denitrification powder. The biomass denitrification powder includes: 50-90% by weight of coal gangue powder; 10-40% by weight of graphite mineral powder; and 5-30% by weight of biomass carbon powder. In one embodiment, the coal gangue powder accounts for 50, 55, 60, 65, 70, 75, 80, 85, 90% by weight of the biomass denitrification powder. In one embodiment, the graphite mineral powder accounts for 10, 15, 20, 25, 30, 35, 40% by weight of the biomass denitrification powder. In one embodiment, the biomass carbon powder accounts for 5, 8, 10, 12, 15, 18, 20, 25, 28, 30% by weight of the biomass denitrification powder. In a preferred technical solution, the biomass denitrification powder is composed of 50-90% by weight of coal gangue powder; 10-40% by weight of graphite ore powder; and 5-30% by weight of biomass carbon powder, and the sum of the components is 100%.

[0031] The biomass denitrification powder is prepared by drying, processing, and uniformly mixing various raw materials in desired amounts.

[0032] In the biomass denitrification powder, coal gangue refers to solid waste discharged during coal mining and coal washing. It is a black-gray rock with a lower carbon content and harder than coal that is associated with coal seams during the coal formation process. The coal gangue powder in this patent can be coal gangue powder sold on the market or obtained by other known means. In one embodiment, the coal gangue powder used in this application is produced in Wuping County, Fujian Province, and is ground to a fineness of 200 mesh and a carbon content of about 25%. The coal gangue powder described in this case can be coal gangue powder of general quality, and there is no excessive requirement for indicators such as carbon content.

[0033] The graphite ore powder used in the biomass denitration powder is a graphite ore powder sold on the market or obtained by other known means, which is obtained by crushing and grinding graphite ore. In one embodiment, the graphite ore powder used in this application is produced in Chenzhou City, Hunan Province, and is ground to a fineness of 200 mesh and a carbon content of about 70%. Those skilled in the art will appreciate that other suitable finenesses or particle sizes, as well as graphite ore powders with other carbon contents are also suitable for the denitration powder of this patent.

[0034] The biomass charcoal powder used in the biomass denitrification powder is a ground powder of biomass charcoal. The biomass charcoal refers to a carbon-containing solid substance obtained by carbonizing biomass materials under anaerobic and heating conditions (preferably 400-800°C). The biomass material includes any non-fossilized plant material, animal material or microbial material (preferably plant material), wherein the biomass material used to prepare the biomass denitrification powder is optionally the same or different from the biomass material used to prepare the biomass denitrification water agent. The biomass material includes agricultural and forestry by-products and / or industrial processing organic waste; preferably, wherein the agricultural and forestry by-products preferably include: branches, leaves, bark, wood, grass, corn cobs, straw, rice husks, fruit shells, shrubs and vines, wherein the industrial organic processing waste includes: bagasse, wood waste (such as sawdust, wood processing waste and forest) and grass waste. Specifically, the biomass charcoal powder used in the test of the present invention is a carbon-containing solid product obtained by heating and carbonizing straw and rice husk under anaerobic conditions, and is ground to a fineness of 200 meshes. Those skilled in the art will appreciate that other suitable biomass materials such as various agricultural and forestry by-products (including straw, rice husks, corn cobs, bean husks, branches, wood, etc.), industrial processing organic waste (such as sugarcane waste in the sugar industry, sawdust and scraps in wood processing, etc.) can also be used to obtain the biomass charcoal powder described in this case under similar conditions, and other suitable finenesses are also suitable for the denitrification powder of this patent.

[0035] There is no particular restriction on the particle size of the biomass denitrification powder, as long as it can be sprayed into the system through an air spray gun at a predetermined rate.

[0036] Regarding the injection position of biomass denitrification powder:

[0037] (Dry process) cement kiln production lines are very large, and nitrogen-containing pollutants are generated in multiple devices or production links. Therefore, there are many choices and combinations of locations for adding denitrification agents. However, the inventors have found through research that the location where the denitrification agent is added has a significant impact on the final effect. When the denitrification agent is added at the addition location known in the prior art or at other devices other than the present invention, the denitrification effect cannot achieve the expected technical effect. After research, the inventors have creatively proposed the following combination of addition locations:

[0038] In this application, the biomass denitrification powder can be used in the following manner (as shown in the attached manual Figure 2 shown):

[0039] The biomass denitrification powder is sprayed at the position from the middle and rear section of the decomposition furnace to the inlet of the lowest cyclone (preferably the upward part of the connecting air duct from the outlet of the decomposition furnace to the lowest cyclone, and most preferably the outlet of the decomposition furnace). The middle and rear section of the decomposition furnace refers to the section between one-third of the height of the decomposition furnace and the outlet of the decomposition furnace, and the direction between one-third of the height of the decomposition furnace and the outlet of the decomposition furnace is from bottom to top. The lowest cyclone refers to the lowest cyclone from bottom to top in one or more cyclones. For example, the lowest cyclone of the five-stage cyclone is the C5 cyclone, the lowest cyclone of the six-stage cyclone is the C6 cyclone, and so on. The outlet of the decomposition furnace is connected to the lowest cyclone through a connecting air duct. The connecting air duct can be any shape determined according to actual conditions. Usually, the connecting air duct includes an upward part and a downward part. The upward part of the connecting air duct is connected to the outlet of the decomposition furnace for exporting gas. The downward part of the connecting air duct connects the upward part and the inlet of the lowest cyclone for introducing gas into the cyclone. The upward portion and the downward portion are intended to indicate that the gas flows through the upward portion first and then through the downward portion, and are not intended to limit the gas flow direction in other meanings.

[0040] In one embodiment, the connecting air duct is curved, and has a shape in which the middle portion is higher than one or both of the two ends, such as an inverted U-shape or an n-shape (also called a gooseneck). In this case, the upward portion also refers to the portion where the gas moves upward, and the downward portion also refers to the portion where the gas moves downward. The outlet of the decomposition furnace described herein is also called the burnout zone.

[0041] The "position" described in this article refers to the position where the biomass denitrification powder is sprayed, which can be used interchangeably with the "injection position".

[0042] In one embodiment of the present invention, the biomass denitrification powder is sprayed from the position using compressed air (eg, high-pressure air).

[0043] In one embodiment, the present application can use multiple / multi-layer spray guns at the injection position. The present invention forms full coverage and uniform spraying through a multi-layer spray gun layout (preferably staggering the spray guns in each layer at a certain angle), thereby improving the utilization efficiency of the biomass flue gas denitrification agent.

[0044] The dosage of biomass denitrification powder is 0.01-1.0 weight % of cement raw material feed (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 weight %). The flue gas denitrification efficiency achieved in the present application can reach more than 90%, for example, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%.

[0045] In the present invention, denitrification efficiency = (background concentration before denitrification - emission concentration after denitrification) / background concentration before denitrification * 100%.

[0046] In addition, the present invention can adjust the amount of biomass denitrification powder sprayed in real time according to the NOx content of flue gas by selecting the type and addition position of the above denitrification agent, and using a metering feeder and a flow control device in the biomass denitrification system, so as to achieve continuous and accurate control of emission indicators. If the powder and water agent are added at other positions, such as the front end of the rotary kiln, it is usually impossible to achieve real-time accurate control of emission indicators.

[0047] In summary, the spraying position of the biomass denitrification powder in the present invention is extremely exquisite (the optimal spraying position is determined based on thousands of hours of industrial online tests), and the spraying amount of the biomass denitrification powder can be automatically controlled and adjusted according to the NOx content in the flue gas, so as to achieve economical, environmentally friendly and efficient flue gas denitrification. The present invention is essentially a technological innovation based on the existing denitrification technology. More hydrocarbon compounds are introduced through biomass powders, and multiple mixing with the materials to be treated is performed under suitable temperature and atmosphere, which significantly improves the removal rate and efficiency of NOx. More importantly, the present invention innovatively uses biomass-derived powders as the main component of the denitrification agent, and introduces the comprehensive treatment concept of waste utilization in the cement environmental protection industry. The main component of the denitrification agent used, biomass denitrification powder, is made by carbonization and thermal cracking of biomass from a wide range of 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, does not affect the quality of clinker, has high denitrification efficiency and low cost. Compared with SCR and SNCR, it has incomparable technical, economic and environmental advantages, and has great application prospects and potential in the field of flue gas denitrification in the cement industry.

[0048] Unless otherwise specified, the percentages, proportions, ratios, contents or parts described in this application are by weight. The concentrations described in this application are by weight concentrations.

[0049] The temperature unit "degree" mentioned in this application refers to Celsius.

[0050] The denitrification agent described in the present application is a denitrification agent used to remove flue gas. Therefore, the term "biomass denitrification agent" in the present application can also be referred to as "biomass flue gas denitrification agent", and the two can be used interchangeably. Similarly, the term "biomass denitrification powder" in the present application can also be referred to as "biomass flue gas denitrification powder", and the two can also be used interchangeably. The term "biomass denitrification water agent" in the present application can also be referred to as "biomass flue gas denitrification water agent", and the two can also be used interchangeably. In this article, the denitrification agent refers to a denitrification water agent and / or a denitrification powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 : An embodiment of position 1, position 2 and position 3 is shown, wherein the relative positions of air, clinker, cooler and fuel are also shown.

[0052] Figure 2 : An implementation method of spraying denitrification agent from position 2.

[0053] Figure 3 : An exemplary spray gun arrangement.

[0054] Figure 4 : An exemplary powder spraying device.

[0055] Description of Reference Numerals

[0056] 1. Position 1

[0057] 2. Position 2

[0058] 3. Position 3

[0059] 4. Rotary kiln

[0060] 5. Kiln tail smoke chamber

[0061] 6. Pre-calciner front section

[0062] 7. Middle section of decomposition furnace

[0063] 8. Rear section of the decomposition furnace

[0064] 9. Connect the upstream part of the air duct

[0065] 10. Connect the downward part of the air duct

[0066] 11.C5 Cyclone

[0067] 12. Cyclone connecting air duct

[0068] 13.C4 Cyclone

[0069] 14.C3 Cyclone

[0070] 15.C2 Cyclone

[0071] 16.C1 Cyclone

[0072] 17. Tertiary air duct

[0073] 21.Biomass denitrification powder storage silo

[0074] 22. Metering feeder

[0075] 23. Powder delivery pipeline

[0076] 24. Air compressor

[0077] 25. Gas flow meter

[0078] 26. Gas valve

[0079] 27. Gas transmission pipeline

[0080] 201.Biomass denitrification powder storage equipment

[0081] 202.Valve equipment

[0082] 203.Measuring equipment

[0083] 204.Measuring equipment

[0084] 205. Pumping equipment

[0085] 206. Compressed air equipment

[0086] 207.Atomizing spray gun equipment DETAILED DESCRIPTION

[0087] In order to better understand the present invention, the content of the present invention is further described below in conjunction with the examples, but the content of the present invention is not limited to the following examples. The experimental operations described in the following examples are conventional operations unless otherwise specified; the reagents and materials described can be obtained from commercial channels unless otherwise specified. The cement production line used in the examples and comparative examples is a five-stage preheater, so the C5 cyclone is the lowest cyclone.

[0088] Embodiment 1:

[0089] The mass percentages of the components in the biomass denitrification powder are: 60% coal gangue powder, 20% graphite powder, and 20% biomass carbon powder.

[0090] This embodiment is used in a 5000t / d new dry process cement production line in Guangdong, and the actual NOx concentration in the flue gas is monitored to be 880mg / m 3Using the existing technology (biomass composite denitrification) spraying system, the biomass denitrification powder is sprayed at the outlet of the decomposition furnace (position 2) through an air pump and a powder spray gun. The spraying amount of biomass denitrification powder is 2t / h (about 0.5% of the cement raw material feed amount). After 10 minutes, the NOx concentration in the flue gas can be stabilized at 340mg / m 3 The denitrification efficiency of cement kiln flue gas is about 61%.

[0091] Embodiment 2:

[0092] The mass percentages of the components in the biomass denitrification powder are: 70% coal gangue powder, 20% graphite powder, and 10% biomass carbon powder.

[0093] This embodiment is used in a 5000t / d new dry process cement production line in Guangdong, and the actual NOx concentration in the flue gas is monitored to be 800mg / m 3 Using the existing technology (biomass composite denitrification) spraying system, the biomass denitrification powder is sprayed at the outlet of the decomposition furnace (position 2) through an air pump and a powder spray gun. The spraying amount of biomass denitrification powder is 2.5t / h (about 0.7% of the cement raw material feed amount). After 10 minutes, the NOx concentration in the flue gas can be stabilized at 320mg / m 3 The denitrification efficiency of cement kiln flue gas is about 60%.

[0094] Embodiment 3:

[0095] The mass percentages of the components in the biomass denitrification powder are: 70% coal gangue powder, 25% graphite powder, and 5% biomass carbon powder.

[0096] This embodiment is used in a 5000t / d new dry process cement production line in Guangdong, and the actual NOx concentration in the flue gas is monitored to be 820mg / m 3 Using the existing technology (biomass composite denitrification) spraying system, the biomass denitrification powder is sprayed at the outlet of the decomposition furnace (position 2) through an air pump and a powder spray gun. The spraying amount of biomass denitrification powder is 3t / h (about 0.8% of the cement raw material feed amount). After 10 minutes, the NOx concentration in the flue gas can be stabilized at 300mg / m 3 The denitrification efficiency of cement kiln flue gas is about 63%.

[0097] Example 4: Preparation of biomass denitrification powder

[0098] About 10 tons of corn stalks were collected, and heated to about 600°C in a carbonization furnace in an airtight manner. About 4 tons of carbon-containing solid products (i.e., biochar) were obtained by carbonization, and ground to a fineness of 200 meshes, and mixed evenly with 4 tons of graphite ore powder and 12 tons of coal gangue powder to obtain 20 tons of biomass denitrification powder for use in Example 1. Different amounts of the aforementioned biomass charcoal powder, coal gangue powder, and graphite ore powder were used to prepare the biomass denitrification powder used in Example 3.

[0099] Example 5: Preparation of biomass denitrification powder

[0100] About 5 tons of dried fruit shells were collected, and heated to about 700°C in a carbonization furnace in an airtight manner. About 2 tons of biomass charcoal was carbonized, ground to a fineness of 200 mesh, and mixed evenly with 4 tons of graphite ore powder and 14 tons of coal gangue powder to obtain 20 tons of biomass denitrification powder, which was used in Example 2 and Comparative Example 3.

[0101] Comparative Example 1:

[0102] This comparative example was used on a 5000t / d new dry process cement production line in Guangdong, and the actual NOx concentration in the flue gas was monitored to be 800mg / m 3 Using the original technology (SNCR selective non-catalytic reduction) spraying system, 900L / h (about 0.25% of the raw material feed) of 20% ammonia water is sprayed at the outlet of the decomposition furnace through a water spray gun. Through 8 spray guns arranged at 45° intervals on the same plane, the denitrification water agent is atomized into droplets less than 10μm by high-pressure air. After 10 minutes, the NOx concentration in the flue gas can be stabilized at 350mg / m 3 The flue gas denitrification efficiency is only 56%.

[0103] Comparative Example 2:

[0104] This comparative example was used in a 5000t / d new dry process cement production line in Anhui Province. The actual NOx concentration in the flue gas was monitored to be 800mg / m 3 At the outlet of the decomposition furnace, 3-5 t / h (1-1.5% of the raw material feed) of coal powder is sprayed by an air pump. After 10 minutes, the NOx concentration in the flue gas can be stabilized at 750-800 mg / m 3 The flue gas denitrification efficiency is about 10% or less, and there is almost no denitrification effect.

[0105] Comparative Example 3:

[0106] This comparative example was used in a 5000t / d new dry process cement production line in Guangdong, and the actual NOx concentration in the flue gas was monitored to be 800mg / m 3The biomass denitrification powder (the mass percentage of each component in the biomass denitrification powder is: 70% coal gangue powder, 20% graphite powder, 10% biomass carbon powder) is all sprayed at the kiln tail smoke chamber (position 1). The spraying amount of biomass denitrification powder is 2t / h (about 0.5% of the cement raw material feed amount). After 10 minutes, the NOx concentration in the flue gas can be stabilized at 720mg / m 3 The denitrification efficiency of cement kiln flue gas is about 10%, which is not significant enough.

[0107] Table 1: Summary of denitrification efficiency

[0108]

[0109] It can be seen from the above examples and comparative examples that, firstly, the biomass denitrification powder used in this patent has a higher denitrification efficiency than the traditional coal powder and ammonia denitrification agent; in addition, the denitrification position selected by this patent has a better denitrification effect than other positions. If the two are combined, an economical, environmentally friendly and efficient denitrification technical solution can be further obtained, and the technical effect of this solution cannot be achieved by all existing technologies.

[0110] The above is only a preferred embodiment of the present invention and does not constitute any form of limitation to the invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A novel dry-process cement kiln biomass denitrification powder, the biomass denitrification powder consisting of 50-90% by weight of coal gangue powder; 10-40% by weight of graphite ore powder; and 5-30% by weight of biomass carbon powder; The biomass carbon powder in the biomass denitrification powder is a ground powder of biomass carbon, and the biomass carbon refers to a carbon-containing solid substance obtained by carbonizing biomass materials under oxygen-deficient and heating conditions.

2. The novel dry-process biomass denitrification powder for cement kilns as claimed in claim 1, wherein the biomass material comprises any non-fossilized plant material, animal material or microbial material.

3. The biomass denitrification powder for cement kiln 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 include: Branches, leaves, bark, wood, grass, corn cobs, straw, rice husks, fruit shells, shrubs and vines, or the industrial processed organic waste includes: bagasse, wood waste and grass waste.

4. The novel dry process biomass denitrification powder for cement kiln as claimed in claim 1, wherein the heating condition comprises heating to 400-800°C.

5. The method for using the novel dry process biomass denitrification powder for cement kiln according to claim 1, Features The biomass denitrification powder is used in the following manner: Biomass denitrification powder is sprayed between the rear section of the decomposition furnace and the entrance of the lowest cyclone.

6. The method according to claim 5, Features The position between the middle and rear section of the decomposition furnace and the entrance of the lowest cyclone is the upward portion of the air duct connecting the exit of the decomposition furnace to the lowest cyclone.

7. The method according to claim 5 or 6, Features The position between the middle and rear section of the decomposition furnace and the entrance of the lowest-stage cyclone is the outlet portion of the decomposition furnace.

8. A novel dry-process biomass denitrification system for cement kilns, comprising a biomass denitrification powder and a powder spraying device, wherein the biomass denitrification powder is as described in any one of claims 1 to 4; the powder spraying device comprises a powder storage bin, a fan, and a powder spray gun, wherein the powder spray gun is installed at a position between the rear section of the decomposition furnace and the entrance of the lowest-level cyclone.

9. The novel dry process biomass denitrification system for cement kiln according to claim 8, Features The powder spraying device also includes a metering feeder, a pneumatic conveying pump, a Roots blower, a powder pipeline, a compressed air pipeline, and a valve.

10. The system according to claim 8 or 9, Features The position between the middle and rear section of the decomposition furnace and the entrance of the lowest cyclone is the upward portion of the air duct connecting the exit of the decomposition furnace to the lowest cyclone.

11. The system of claim 8, Features The position between the middle and rear section of the decomposition furnace and the entrance of the lowest-stage cyclone is the outlet portion of the decomposition furnace.

Images