CN102392093A - Direct reduction iron making device and method based on biomass - Google Patents

Abstract

The invention provides a direct reduction ironmaking device and method based on biomass, the device includes a blower fan, an air powder premixing pipe, a biomass feeder and a combustion chamber, and the biomass feeder and air powder premixing pipe One end of the air powder premixing pipe is connected to the fan, and the other end is connected to the combustion chamber. The bottom of the combustion chamber is provided with a slag outlet, the top is provided with a flue gas outlet, and the middle part is provided with a reactor for direct reduction ironmaking. The direct reduction ironmaking method includes preparation of green pellets, preheating and direct reduction. The heat source required for preheating and reduction is provided by biomass combustion, and the synthesis gas prepared by catalytic gasification of biomass is used as the reducing agent required for the reduction process. The invention adopts biomass instead of coal and natural gas to carry out direct reduction ironmaking, gets rid of the dependence of the ironmaking industry on fossil energy, improves the quality of direct reduced iron products and reduces the harm to the environment, and fundamentally solves the problem of green ironmaking industry technical and equipment issues.

Description

A direct reduction ironmaking device and method based on biomass

technical field

The invention belongs to the technical field of ironmaking, and in particular relates to a biomass-based direct reduction ironmaking device and method.

Background technique

The iron and steel industry is an important basic industry for the development of the national economy and an important symbol of the country's economic level and comprehensive national strength. Modern steelmaking raw materials mainly come from blast furnace ironmaking, a small amount of scrap steel and direct reduced iron. In the world iron and steel industry, about 60% of the supply of pig iron for steelmaking comes from blast furnaces, while in my country almost 90% comes from blast furnace ironmaking. my country's blast furnace ironmaking technology has encountered two major contradictions in the modern iron and steel industry: one is the contradiction between the high-quality coking that blast furnace ironmaking technology strongly relies on and the increasingly scarce coal reserves; the other is the increasing environmental protection requirements and the traditional blast furnace The contradiction between ironmaking technology and serious environmental pollution. The above two contradictions have seriously affected the sustainable development of my country's iron and steel industry, and forced people to seek new fuels to replace metallurgical coke. Therefore, the development of new ironmaking fuels and the research on corresponding ironmaking processes are of great strategic significance to the development of the national economy.

At present, the new fuels that replace metallurgical coke ironmaking at home and abroad are mainly coal powder and natural gas, and the new ironmaking technology researched mainly includes non-blast furnace ironmaking technologies such as direct reduction and smelting reduction.

The direct reduction method uses gaseous fuel, liquid fuel or non-coking coal as energy sources to obtain metallic iron through reduction below the softening temperature of iron ore (or iron-containing agglomerates). Its product has a porous low-density sponge-like structure and is called direct reduced iron or sponge iron. According to the different main energy sources, the direct reduction process can be divided into three categories: coal-based direct reduction, gas-based direct reduction and electric thermal direct reduction. At present, gas-based direct reduction is the main method, accounting for about 85%. It converts natural gas into the required reducing agent, and then reduces lump ore or pellets in the shaft furnace.

At present, the gas-based direct reduction ironmaking method has the following disadvantages:

(1) Abundant natural gas resources must be used as a guarantee;

(2) The reaction temperature is low, the reaction speed is slow, and the charge stays in the reduction zone for a long time;

(3) Using pure hydrogen as the reducing agent can improve the production efficiency of the whole process, but the operating cost is relatively high;

(4) High requirements on iron ore particle size and grade;

To sum up, the purpose of non-blast furnace ironmaking technology development is to use coal or natural gas instead of coking coal. The energy structure has not undergone a fundamental change, and it is still inseparable from fossil energy, which is harmful to environmental pollution, especially carbon reduction. The platoon has not improved fundamentally. At the same time, their energy consumption is higher than that of blast furnace ironmaking, and their quality is still far from that of blast furnace ironmaking. Their comprehensive benefits have no advantages, and their research and application progress is slow.

Contents of the invention

Aiming at the deficiency and defect that the ironmaking technology in the prior art is inseparable from fossil energy, the present invention provides a direct reduction ironmaking device and method based on biomass. The present invention mixes biomass powder and iron ore powder to produce raw Pellets, direct reduction ironmaking using hydrogen-rich and carbon monoxide-rich synthesis gas generated by catalytic gasification of biomass as reducing agent. The invention has small investment, low cost, high production efficiency and high quality of obtained products.

In order to achieve the above-mentioned purpose of the invention, the present invention adopts the following technical solutions to achieve:

A kind of direct reduction ironmaking device based on biomass, it comprises blower fan, air powder premixing pipe, biomass feeder and combustion chamber, and described biomass feeder communicates with air powder premixing pipe, and described air powder One end of the premixing pipe is connected to the fan, and the other end is connected to the biomass powder in the lower part of the combustion chamber and the combustion air inlet. A reactor for direct reduction ironmaking is provided, the top of the reactor is provided with a reduction waste gas outlet, and the bottom of the reactor is connected with a biomass synthesis gas intake pipe.

A further improvement to the technical solution: a biomass synthesis gas distribution plate is arranged on the upper part of the biomass synthesis gas inlet pipe at the bottom of the reactor.

A further improvement to the technical solution: a thermocouple is provided in the middle of the reactor.

A further improvement to the technical solution: the biomass and the combustion air inlet are connected to the combustion chamber along the tangential direction of the lower part of the combustion chamber.

Further improvement on the technical solution: the combustion chamber is cylindrical.

The present invention also provides a direct reduction ironmaking method based on biomass, said method comprising the following steps:

(1) Green pellets are prepared by mixing 70-85% of iron concentrate powder, 10-15% of biomass powder, 5-10% of dolomite, 3-5% of binder and 5-10% of water to make green pellets. pellets;

(2) Preheating, placing the green pellets in a kiln for preheating, the preheating temperature is controlled at 600-800°C, and the reactor uses burning biomass powder as an external heating source;

(3) Direct reduction. After the preheating is completed, increase the temperature of the kiln to reach 800-1000°C, and then feed biomass synthesis gas prepared by catalytic biomass gasification into the kiln as a reducing agent, and continuously feed 1 -2h, the direct reduced iron or pure pig iron will be obtained, and the unreacted synthesis gas and waste gas generated by the reduction reaction will enter the combustion chamber for combustion to compensate for the heat required for the reduction reaction.

Further improvement on the technical solution: the external heat source required for the pellet preheating and reduction process is provided by biomass combustion.

Further improvement to the technical solution: the binder is a mixture of any one or more binders in bentonite or organic binders, preferably bentonite.

Further improvement on the technical solution: the shape of the green pellets is spherical, square, cylindrical, preferably cylindrical or spherical.

Compared with prior art, advantage and positive effect of the present invention are:

(1) The present invention mixes biomass powder and iron ore powder to produce green pellets, and the biomass is decomposed by heat during the preheating and consolidation process of the green pellets, which increases the surface pore volume of the sintered ore.

(2) The present invention uses high-efficiency combustion of biomass powder to provide an external heat source for the direct reduction of iron ore.

(3) The present invention uses the synthesis gas rich in hydrogen and carbon monoxide generated by catalytic gasification of biomass as the reducing agent, and the synthesis gas preparation cost is low and the hydrogen content in it can reach more than 60%.

(4) The present invention fundamentally solves the technical problems of clean production in the ironmaking industry, gets rid of the ironmaking industry's dependence on fossil energy, and realizes zero CO2 emissions in ironmaking production.

(5) The carbon content of the iron produced by the present invention is very low, only less than 0.5%. That is to say, this direct reduction technology can smelt crude steel in one step, saves coke, and reduces carbon energy loss and steelmaking costs. cost.

Other characteristics and advantages of the present invention will become clearer after reading the detailed description of the present invention in conjunction with the accompanying drawings.

the

Description of drawings

Fig. 1 is a schematic structural view of the direct reduction ironmaking device of the present invention.

Fig. 2 is a process flow chart of the direct reduction ironmaking method of the present invention.

Fig. 3a is the green pellet made by mixing biomass and iron ore powder in the present invention.

Fig. 3b is a diagram of direct reduction ironmaking products produced in the present invention.

the

Detailed ways

The technical solutions of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example 1

As shown in Figure 1, the present invention provides a kind of direct reduction ironmaking plant based on biomass, and it comprises fan 1, air powder premixing pipe 2, biomass feeder 3 and combustion chamber 4, and described biomass feeds The feeder 3 is in communication with the air powder premixing pipe 2, one end of the air powder premixing pipe 2 is connected with the fan 1, and the other end is the biomass powder and the combustion air inlet 5, and the biomass powder and the combustion air inlet 5 It extends into the interior of the combustion chamber 4 along the tangential direction of the lower part of the combustion chamber 4. After the biomass delivered by the biomass feeder 3 and the combustion-supporting air provided by the fan 1 are fully mixed in the air-powder pre-mixing pipe 2, the powder and the combustion-supporting air are mixed together. The air inlet 5 enters the combustion chamber 4 for combustion.

The combustion chamber 4 is cylindrical, the bottom of the combustion chamber 4 is provided with a slag outlet 6, and the top is provided with a flue gas outlet 7, and the flue gas generated by combustion is discharged from the flue gas outlet 7 at the top of the combustion chamber 4, and the remaining ash It is discharged from the slag outlet 6 at the bottom of the combustion chamber 4 . The middle part of the combustion chamber 4 is provided with a reactor 8 for direct reduction ironmaking, and the top of the reactor 8 is provided with a reduction waste gas outlet 12, and the bottom of the reactor is connected with a biomass synthesis gas intake pipe 11, and the reactor 8 generates A biomass synthesis gas distribution plate 10 is provided on the upper part of the material synthesis gas inlet pipe 11, and a thermocouple 9 is provided at the middle part of the reactor.

As shown in Figure 2, the present invention also provides a direct reduction ironmaking method based on biomass, said method comprising the following steps:

(1) Green pellet preparation. Select 75% of iron concentrate powder with a taste of 65.2%, 10% of biomass powder, 5% of dolomite, 3% of bentonite and 7% of water for mixing, and press it into spherical green pellets through a roller briquetting machine. 20mm, as shown in Figure 3a.

(2) Preheat. Place the pellets in the reactor for preheating. The reactor uses burning biomass powder as an external heating source. The preheating temperature is controlled at 800°C and kept at a constant temperature for 0.5 hours to ensure that the biomass in the raw material is fully pyrolyzed .

(3) Direct reduction. After the preheating process is completed, increase the temperature in the reactor. When the temperature in the reactor reaches 1000°C, feed the biomass synthesis gas (H ₂ 52.0wt%, CO 24.6wt%) prepared by the catalytic gasification of biomass into the reactor. %, CO ₂ 18.8wt%, CH ₄ 2.7wt%), using the biomass synthesis gas as the reducing agent to carry out the reduction reaction to obtain direct reduced iron or pure pig iron, the unreacted synthesis gas and the waste gas generated by the reduction reaction enter The combustion chamber burns to compensate for the heat required for the reduction reaction.

The appearance and inspection results of the prepared direct reduced iron or pure pig iron are shown in Figure 3b and Table 1, respectively:

Table 1: DRI composition of DRI or pure pig iron

Element Al Si P S Ca mn MFe other composition/% 2.73 6.80 0.03 0.02 1.02 0.36 86.89 2.15

There are three main reduction reactions in the whole direct reduction ironmaking process:

1. The residual coke from biomass pyrolysis is retained in the pellets and undergoes a reduction reaction with iron oxides.

2. The volatile matter generated by biomass pyrolysis is catalyzed by dolomite and bentonite in the pellets during the process of leaving the pellets, and is catalytically converted into carbon monoxide, hydrogen and low molecular hydrocarbons to participate in the reduction reaction of iron oxides.

3. A reduction reaction occurs between the synthesis gas and the iron oxides in the pellets. The biomass in the pellets is thermally decomposed during the preheating process, and the volatile matter generated by pyrolysis is detached from the surface of the pellets, resulting in an increase in the surface porosity and expansion of the pore volume of the pellets, which promotes heat transfer, The progress of mass transfer increases the reduction reaction rate and reduction degree.

Biomass in the present invention mainly refers to lignocellulose (lignin for short) such as straws and trees other than grain and fruit in the agricultural and forestry production process, leftovers from the agricultural product processing industry, agricultural and forestry waste, and poultry and livestock in the animal husbandry production process. Substances such as feces and waste. Biomass has the advantages of renewability, low pollution and wide distribution. In the direct reduction ironmaking method, the external heat source required for the sintering and reduction process of forming raw materials is provided by biomass combustion. Biomass catalytic gasification produces biomass synthesis gas. The gasification medium used in the catalytic gasification process is steam, and the catalyst used is dolomite, nickel-based catalyst or a mixture of dolomite and nickel-based catalyst. The synthesis gas rich in hydrogen and carbon monoxide generated by catalytic gasification of biomass enters the reactor 8 through the biomass synthesis gas inlet pipe 11, and is evenly distributed through the biomass synthesis gas distribution plate 10, and then undergoes a reduction reaction with the sintered molding raw materials. The waste gas produced after the reaction is discharged through the reduction waste gas outlet 12 at the top of the reactor 8 or enters the combustion chamber for combustion.

The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art can still understand the foregoing embodiments. Modifications are made to the technical solutions described, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions claimed in the present invention.

Claims (9)

1. direct reduction iron making device based on biomass; It is characterized in that: it comprises blower fan, wind powder premix barrel, biomass feeder and combustion chamber, and said biomass feeder is communicated with wind powder premix barrel, and said wind powder premix barrel one end links to each other with blower fan; The other end is to be connected with combustion air inlet with the biomass powder of bottom, said combustion chamber; Bottom, said combustion chamber is provided with slag-drip opening, and the top is provided with exhanst gas outlet, and the middle part, combustion chamber is provided with the reactor drum that is used for direct reduction iron making; Said reactor head is provided with reduction waste gas air outlet, and reactor bottom links to each other with the biomass synthesis gas inlet pipe.

2. a kind of direct reduction iron making device based on biomass according to claim 1 is characterized in that: be provided with the biomass synthesis gas grid distributor on said reactor bottom biomass synthesis gas inlet pipe top.

3. a kind of direct reduction iron making device based on biomass according to claim 1 is characterized in that: be provided with thermopair in said reactor drum middle part.

4. a kind of direct reduction iron making device based on biomass according to claim 1 is characterized in that: tangential direction is connected with the combustion chamber said biomass along the bottom, combustion chamber with combustion air inlet.

5. a kind of direct reduction iron making device based on biomass according to claim 1, it is characterized in that: said combustion chamber is cylindrical.

6. direct reduction iron making method based on biomass is characterized in that: said method comprising the steps of:

(1) green pellets preparation is mixed and made into green pellets by fine iron breeze 70-85%, powdered biomass 10-15%, rhombspar 5-10%, sticker 3-5% and water 5-10%;

(2) preheating is positioned over said green pellets and carries out preheating in the kiln, and preheating temperature is controlled at 600 ~ 800 ℃, said reactor drum with the biomass burning powder as external heat source;

(3) directly reduction; After preheating is accomplished, after increasing kiln temperature and making it reach 800 ~ 1000 ℃, in kiln, feed biomass synthesis gas by the Biomass Catalytic Gasification preparation as reductive agent; Continue to feed 1-2h; Promptly obtain the dri or the pure pig iron, the unreacted waste gas that produces of synthetic gas and reduction reaction completely gets into combustion chambers burn, with the required heat of compensation reduction reaction.

7. according to the described direct reduction iron making method based on biomass of claim 6, it is characterized in that: said green pellets preheating and the required external heat source of reduction process are provided by biomass combustion.

8. the direct reduction iron making method based on biomass according to claim 6 is characterized in that: said sticker is the mixture that any one or more than one sticker is formed in wilkinite or the organic binder bond, is preferably wilkinite.

9. the direct reduction iron making method based on biomass according to claim 6 is characterized in that: being shaped as of said green pellets is spherical, square, cylindrical, is preferably cylindrical or spherical.

Images