阅读说明：本技术 一种链篦机-回转窑喷吹生物质燃料及其制备方法和应用 (Chain grate-rotary kiln injected biomass fuel and preparation method and application thereof ) 是由 季志云 范晓慧 甘敏 倪佳苗 李浩锐 陈许玲 黄晓贤 袁礼顺 黄斌斌 武钰峰 吕 于 2019-10-10 设计创作，主要内容包括：本发明公开了一种链篦机-回转窑喷吹生物质燃料及其制备方法和应用。将生物质粉末与含铁矿物粉末充分混匀后,在保护性气体及水蒸气混合气氛下,进行升温炭化,即得挥发分含量为10～20％、燃烧热值为20～27MJ/kg、孔隙率为40～60％、比表面积为40～70m<Sup>2</Sup>/g的生物质燃料,将其替换部分常规喷吹燃料煤粉用于回转窑窑尾喷吹燃料,可以降低燃料成本,且有利于从源头上高效减排SOx、NOx。(The invention discloses a grate-rotary kiln injected biomass fuel and a preparation method and application thereof. After the biomass powder and the iron-containing mineral powder are fully mixed, heating and carbonizing are carried out under the mixed atmosphere of protective gas and steam, and the biomass powder and the iron-containing mineral powder are obtained, wherein the volatile content is 10-20%, the combustion heat value is 20-27 MJ/kg, the porosity is 40-60%, and the specific surface area is 40-70 m 2 The/g biomass fuel replaces part of conventional injection fuel coal powder to be used as the rotary kiln tail injection fuel, so that the fuel cost can be reduced, and the efficient emission reduction of SOx and NOx from the source is facilitated.)

1. A method for preparing a biomass fuel by using waste biomass through a grate-rotary kiln is characterized by comprising the following steps: and (3) fully and uniformly mixing the biomass powder and the iron-containing mineral powder, and then heating and carbonizing in a mixed atmosphere of protective gas and steam to obtain the biomass powder.

2. The method for preparing a grate-kiln injected biomass fuel using waste biomass as claimed in claim 1, wherein:

the biomass comprises at least one of agricultural wastes such as wheat straws, rice straws, corn straws, rice hulls, fruit pits, fruit shells, sawdust and municipal sludge, forestry processing wastes and municipal waste biomass;

the iron-containing mineral comprises Fe as main ingredient₂O₃·xH₂O and/or FeCO₃At least one of the iron-containing minerals.

3. The method for preparing a grate-kiln injected biomass fuel using waste biomass as claimed in claim 1 or 2, wherein: the mass percentage of the biomass powder to the iron-containing mineral powder is 97-99%: 1-3% of the composition.

4. The method for preparing a grate-kiln injected biomass fuel using waste biomass as claimed in claim 3, wherein:

the granularity of the biomass powder meets the requirement that the mass percentage of the particle size of 100-300 mu m is not less than 70%;

the granularity of the iron-containing mineral meets the requirement that the mass percentage content of the particle fraction of less than or equal to 50 mu m is not less than 80 percent.

5. The method for preparing a grate-kiln injected biomass fuel using waste biomass as claimed in claim 1, wherein: the volume percentage composition of the mixed atmosphere is that argon 15-25%, nitrogen 70-80%, vapor 5-15%, and the total gas flow is 0.1-0.5L/min.

6. The method for preparing the biomass fuel injected by the chain grate-rotary kiln by using the waste biomass as claimed in any one of claims 1 to 5, wherein the method comprises the following steps: the carbonization process comprises the following steps: the temperature is rapidly raised to 300-600 ℃ at a speed of 40-80 ℃/min, and the temperature is kept for 20-40 min.

7. A chain grate-rotary kiln jetting biomass fuel is characterized in that: prepared by the method of any one of claims 1 to 6.

8. The grate-rotary kiln injected biomass fuel as claimed in claim 7, wherein: the grate-rotary kiln injected fuel has the volatile content of 10-20%, the combustion heat value of 20-27 MJ/kg, the porosity of 40-60%, and the specific surface area of 40-70 m²/g。

9. Use of a grate-kiln for injecting biomass fuel according to claim 7 or 8, characterized in that: replace the pulverized coal fuel injected into the rotary kiln.

10. Use of a grate-kiln for injecting biomass fuel according to claim 9, characterized in that: and replacing 60-100% of pulverized coal fuel injected into the rotary kiln with equal heat for use.

Technical Field

The invention relates to a grate-rotary kiln biomass fuel injection method, in particular to a grate-rotary kiln biomass fuel injection method prepared by utilizing waste biomass, and a preparation method and application thereof. Belongs to the technical field of oxidized pellet production.

Background

In recent years, the national issue of environmental pollution is more and more focused, and relevant laws and regulations are more and more strict for emission standards of exhaust pollutants. Iron and steel enterprises are industries with high energy consumption and high pollution, and sintering and pelletizing processes in the whole iron and steel smelting process are main energy consumption and atmospheric pollutant discharge links. Currently, the industry mainly focuses on the treatment of flue gas pollutants in a sintering process with larger pollutant discharge amount, and less focuses on the purification of discharged flue gas in the pellet production process. According to the 2019 ultra-low emission requirement of the steel pellet flue gas, the hourly average values of the emission concentrations of the particulate matters, the sulfur dioxide and the nitrogen oxides in the flue gas are respectively not higher than 10, 35 and 50mg/m³And the average hourly discharge concentration of at least more than 95 percent of the period per month of the iron and steel enterprises with ultralow discharge meets the indexes. But the sintering pellet flue gas NOx and SO are currently₂The average emission concentration exceeds the ultra-low emission limit more, and the same will be facedAnd (4) severe emission reduction pressure.

The pellet production is an important link of iron and steel enterprises, and the main production process comprises a shaft furnace method, a grate-rotary kiln method and a belt type roasting machine method, wherein the grate-rotary kiln method has the characteristics of large scale, low energy consumption and high quality, and is widely applied at home at present. The fuel produced by the pellets can use three fuels of gas, liquid and solid, and has wide available resources, wherein the utilization of the coal dust is a great characteristic of fuel combustion, and can be well adapted to the current resource situation of China. However, the content of sulfur and nitrogen in the fossil fuel coal powder is high, the fossil fuel coal powder is a main source of SOx and NOx in pellet flue gas, the ash content of the fossil fuel is high, and the rotary kiln is easy to form rings after long-term injection, so that the production efficiency is adversely affected.

Biomass energy refers to a form of energy in which solar energy is stored in biomass in the form of chemical energy, and is the fourth largest resource next to petroleum, natural gas and coal. The biomass has the characteristics of cleanness and regeneration, the S, N content of the biomass is low, and the ash content generated after combustion is obviously lower than that of fossil fuel. It is estimated that about 1600 million tons of biomass produced by photosynthesis on earth per year is currently under utilization of this part of energy in China. If a proper preparation technology is developed and the biomass is applied to the pellet roasting process, the energy structure of the iron and steel enterprises can be obviously improved, and particularly, the emission of SOx and NOx in the pellet production process can be effectively reduced from the source, and the ring formation period is shortened.

Disclosure of Invention

Aiming at the problems of high pollution and easy ring formation of the grate-rotary kiln process in pellet production in the prior art when pulverized coal is used as injection fuel, the invention aims to provide the grate-rotary kiln injection biomass fuel which has high heat value and good chemical reactivity, and can greatly reduce the smoke pollution of the process and prolong the ring formation period of the rotary kiln when the fuel is mixed with the pulverized coal for injection.

The second purpose of the invention is to provide a method for preparing a chain grate-rotary kiln injected biomass fuel by using waste biomass, the method has simple steps, the raw material is derived from the waste biomass, and the resource utilization of the biomass is realized.

The third purpose of the invention is to provide the application of the biomass fuel injected into the grate-rotary kiln in the pellet sintering of the grate-rotary kiln, wherein the injected biomass fuel can replace fossil fuel at a high ratio, the emission of sintering smoke pollutants is greatly reduced, and the sintering cost is reduced.

In order to achieve the technical purpose, the invention provides a method for preparing a grate-rotary kiln injection fuel by utilizing waste biomass.

The invention adjusts and controls the physicochemical characteristics of the waste biomass by introducing the iron-containing minerals, and prepares the high-quality biomass fuel suitable for being injected by the rotary kiln.

In a preferred scheme, the biomass comprises at least one of agricultural wastes such as wheat straws, rice straws, corn straws, rice hulls, fruit pits, fruit shells, sawdust and municipal sludge, forestry processing wastes and municipal waste biomass.

Preferably, the iron-containing mineral includes Fe as a main component₂O₃·xH₂O and/or FeCO₃At least one of the iron-containing minerals. The low-grade iron ore selected by the invention can be decomposed to release H in the biomass pyrolysis process₂O or CO₂The atmosphere of the biomass reaction micro-area is optimized, and the reaction activity of the biomass is favorably regulated and controlled from inside to outside; the iron oxide in the iron-containing additive can promote the cracking of biomass organic matter macromolecules into micromolecular substances and is beneficial to residual active groups on the surface of the biomass fuel; in the whole pyrolysis process, the existence of partial ferric oxide catalyzes the cracking of tar, and the utilization value of fuel gas generated by pyrolysis is higher.

According to the preferable scheme, the biomass powder and the iron-containing mineral powder are 97-99% by mass: 1-3% of the composition.

In a preferable scheme, the granularity of the biomass powder meets the requirement that the mass percentage content of the biomass powder in a size fraction of 100-300 mu m is not less than 70%.

In a preferable scheme, the iron-containing mineral has a granularity of 0-50 μm (less than or equal to 50 μm) and the mass percentage content of the iron-containing mineral is not less than 80%.

In a preferred scheme, the volume percentage of the mixed atmosphere is 15-25% of argon, 70-80% of nitrogen and 5-15% of water vapor, and the total flow of the gases is 0.1-0.5L/min. In the process of pyrolysis, H is introduced₂O (g) is used for regulating and controlling the reaction atmosphere, so that a new surface is formed by the reaction with the carbon in the biomass in the pyrolysis process, the active sites of combustion reaction are further increased, and the reaction activity of the carbonized product is enhanced.

Preferably, the carbonization process is as follows: the temperature is rapidly raised to 300-600 ℃ at a speed of 40-80 ℃/min, and the temperature is kept for 20-40 min. Through the rapid heating pyrolysis process, a large amount of pore structures are remained when the volatile macromolecules are violently pyrolyzed, which is beneficial to improving the reaction activity of the product.

Preferably, the steam can be produced by recovering industrial waste heat. For example, surplus steam of iron and steel enterprises, particularly water steam generated by thermal power plants, sintering flue gas, converter flue gas and waste heat boilers at the bottom of a heating furnace in the iron and steel plants, improves the energy utilization rate.

The invention also provides a grate-rotary kiln injected biomass fuel which is prepared by the method.

Preferably, the biomass fuel injected by the chain grate-rotary kiln has the volatile content of 10-20%, the combustion heat value of 20-27 MJ/kg, the porosity of 40-60% and the specific surface area of 40-70 m²/g。

The invention also provides application of the grate-rotary kiln to blowing the biomass fuel, which is used for replacing the rotary kiln to blow the pulverized coal fuel.

In the preferable scheme, 60-100% of pulverized coal fuel injected into the rotary kiln is replaced by equal heat. Most preferably biomass fuel and coal powder according to the mass ratio of 60-80: 20-40.

The prepared biomass fuel replaces part of the pulverized coal to be mixed and blown, the biomass fuel particles with high reactivity play a role in quickly burning and igniting the pulverized coal to the pulverized coal particles with lower reactivity, the burning efficiency of the pulverized coal can be improved, the biomass fuel has the characteristic of high C-H, a fuel-rich reaction zone is formed around the pulverized coal particles, and the generation of NOx generated by pulverized coal burning is favorably inhibited.

The biomass fuel is partially used for replacing the conventional fuel coal powder injected into the rotary kiln, and is uniformly mixed with the conventional fuel coal powder injected into the rotary kiln from the tail part of the rotary kiln for combustion.

Compared with the prior art, the invention has the following beneficial effects:

(1) the biomass fuel preparation process provided by the invention adopts a relatively fast heating rate to rapidly heat the biomass to the target temperature, so that the biomass pyrolysis process can be accelerated, a large amount of pore structures are remained when the volatile macromolecules are violently pyrolyzed, and the reaction activity of the product is favorably improved; and the surplus H produced by the iron and steel enterprises is introduced in the pyrolysis process₂O (g) is used for regulating and controlling the reaction atmosphere, so that a new surface is formed by the reaction with the carbon in the biomass in the pyrolysis process, the active sites of combustion reaction are further increased, the reaction activity of carbonized products is enhanced, and cheap and easily obtained byproducts of steel enterprises are fully utilized.

(2) The low-grade iron ore additive added in the invention is uniformly dispersed in the biomass particles and can be decomposed to release H in the biomass pyrolysis process₂O or CO₂The atmosphere of the biomass reaction micro-area is optimized, and the reaction activity of the biomass is favorably regulated and controlled from inside to outside; the iron oxide in the iron-containing additive can promote the cracking of biomass organic matter macromolecules into micromolecular substances and is beneficial to residual active groups on the surface of the biomass fuel; in the whole pyrolysis process, the existence of partial ferric oxide catalyzes the cracking of tar, and the utilization value of fuel gas generated by pyrolysis is higher.

(3) According to the invention, the biomass fuel and the coal powder are mixed and injected, the biomass fuel particles with high reactivity are closely contacted and mutually wrapped with the coal powder particles with lower reactivity, and the biomass fuel can rapidly burn and rapidly ignite the coal powder in the combustion process, so that the combustion efficiency of the coal powder can be improved; on the other hand, the biomass fuel has the characteristic of high C-H, and a fuel-rich reaction zone is formed around the pulverized coal particles, so that the generation of NOx generated by pulverized coal combustion is inhibited; in the invention, part of iron oxide components are introduced in the preparation process of the biomass fuel, and the biomass fuel can serve as a catalyst in the fuel combustion process, promote the combustion of biomass and coal dust and improve the energy utilization efficiency.

(4) The waste biomass is prepared into the high-quality fuel suitable for being injected by the rotary kiln, so that the value-added utilization of resources is realized, the content of the biomass coke S, N is low, the emission of sulfur oxides and nitrogen oxides in the pellet production process can be reduced from the source, the problem of environmental pollution can be effectively relieved, and meanwhile, the ash content is low, the ring formation period in the rotary kiln can be obviously reduced, so that the rotary kiln can efficiently and stably run; the iron-containing additive adopted in the invention is a cheap raw material which is easy to obtain in the pellet production process, and has little influence on the preparation cost of the biomass fuel.

Detailed Description

In order to facilitate an understanding of the present invention, the present invention will be described more fully and in detail with reference to the preferred embodiments, but the scope of the present invention is not limited to the specific embodiments described below.

Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.

Unless otherwise specified, the reagents and materials used in the present invention are commercially available products or products obtained by a known method.