JPS61288004A - Utilizing method for converter waste gas - Google Patents

Abstract

PURPOSE:To effectively utilize converter waste gas by introducing the converter waste gas into a carbonaceous material fluidized bed and converting the gas then storing such gas, further increasing the temp. of the stored gas and introducing the gas into a powdery iron ore fluidized bed thereby reducing the iron ore. CONSTITUTION:The carbonaceous material is charged through a charging port 6 into the fluidized bed 5 and the converter waste gas under blowing is introduced into the fluidized bed 5 as the 1st stage. The CO2 and H2 in the gas are converted to CO, H2 by the above-mentioned carbonaceous material and the gas is once stored in a gas holder 19. The above-mentioned carbonaceous material is discharged from a discharge port 8 of the fluidized bed 5 and thereafter the preheated iron ore is charged through the port 6 into the fluidized bed as the 2nd stage. The stored gas is then introduced by an intensifying blower 10 into the fluidized bed 5 and part of the gas is partially burned to increase the temp. of the gas to a prescribed temp. The iron ore is thereby reduced. The iron ore after the reduction is discharged from a discharge port 7. The converter gas is thus effectively utilized for the gas conversion and the ore reduction without receiving the restriction for the blowing time of the converter 1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of utilizing converter exhaust gas, and a method for effectively utilizing converter exhaust gas in a powder ore reduction process equipped with a fluidized bed @ reduction furnace. Regarding.

[Conventional technology]

The molten metal production process using the smelting-reduction method has replaced traditional technologies such as the production of pig iron using a blast furnace using high-quality coke and sintered ore as raw materials, and the production method of ferroalloy using an electric furnace using electricity as energy. Development is underway. In such a process, a large amount of exhaust gas is generated from the smelting reduction furnace, and in order to reduce energy consumption and costs by using this effectively, it is necessary to use the exhaust gas from the smelting reduction furnace to pre-reduce ore. It is necessary to use it for

Smelting reduction furnaces used in such molten metal production processes include converter-type furnaces that operate in batches and blast furnace-type furnaces that operate continuously. On the other hand, examples of pre-reduction furnaces include rotary kilns, shaft furnaces, and fluidized bed furnaces.

By combining these, several types of processes can be configured, and the combination process of a converter and a rotary kiln is described in JP-A-59-113158, JP-A-59-145758, JP-A-60-2613, and JP-A-60-2613. Techniques such as Sho 60-2614 have been disclosed.

Further, Japanese Patent Application Laid-Open No. 120607/1983 discloses a combination of a blast furnace type smelting reduction furnace and a shaft furnace type preliminary reduction furnace.

[Problem that the invention seeks to solve]

The present invention differs from these prior art techniques in that it provides a new process technology that involves a combination of a converter-type smelting reduction furnace and a fluidized bed pre-reduction furnace.

That is, the combination of a converter-type smelting reduction furnace and a fluidized bed reduction furnace has the following problems.

■ Converters operate in batches, and the gas composition fluctuates greatly. During this fluctuation, large amounts of components that interfere with the reduction reaction, such as CO2 and H2O in the case of iron ore reduction, are generated.
Present in high concentrations in gases. This gas composition also varies depending on the operating conditions of the converter.

■ Since the blowing time of the converter is short, the reduction in the fluidized bed reduction furnace does not finish during the gas generation period, and the timing is not correct.

An object of the present invention is to provide a method for effectively utilizing converter exhaust gas that solves these problems.

[Means for solving problems]

The present invention is a method for utilizing converter exhaust gas, which guides converter exhaust gas into a fluidized bed, transforms the converter exhaust gas, and reduces iron ore, the method comprising: a) filling the fluidized bed with carbonaceous material; During converter blowing, the converter exhaust gas is directly introduced into the fluidized bed, and the high temperature of the gas raises the temperature of the carbonaceous material and removes CO2, which is a component that interferes with reduction.
, H2O is metamorphosed with carbonaceous material and this gas is stored; b) Part of the stored gas is partially oxidized and heated to a high temperature, and this gas is introduced into a fluidized bed to reduce the ore. It is characterized by consisting of two stages and one floor.

[Effect]

In the first stage, a fluidized bed is formed using particles containing carbonaceous material as a fluidized medium, and converter exhaust gas is introduced into this fluidized bed, so CO2 and H20 in the exhaust gas react with the carbonaceous material, resulting in co2+c→2CO H20+C-+CO+H2 CO2 and H2O are converted into CO and H2 by the reaction. Since this reaction is endothermic, the gas temperature also decreases.

In the second stage, CO2 and H2O are metamorphosed and the stored gas is partially combusted to a high temperature and used as reducing gas for the powdered ore in the fluidized bed reduction furnace, so the reduction reaction rate in the reduction furnace is high. Furthermore, the problem of the timing not matching between the blowing time of the converter and the reduction time of the fluidized bed reduction furnace is also solved. Furthermore, in order to match the time cycle of blowing and end of blowing in the converter with the time cycle of gas conversion and ore reduction in the fluidized fluidized reduction furnace, it is preferable to install two fluidized fluidized reduction furnaces and perform alternate operation. It is.

〔Example〕

An example of the reduction reaction of iron ore will be described below with reference to the process diagrams of FIGS. 1 and 2. Note that although this example mainly uses iron ore, other ores may also be used.

50ONm'' of exhaust gas from the 5-ton converter 1 is introduced into the fluidized bed 5 to reduce iron ore, resulting in 43kg of reduced ore with a reduction rate of 52%.
was manufactured.

First, in the first step, 480 kg of carbonaceous material mainly consisting of coke is charged into the fluidized bed 5 from the charging port 6, and the cutoff valve 3 is connected to the gas pipe to block the converter exhaust gas during blowing into which oxygen for blowing is blown. 4, the carbonaceous material is fluidized and heated, converting CO2 in the converter exhaust gas to CO. After heat exchange (preheating iron ore, etc.) and cooling, the converted gas is passed through a gas hole.
It was stored in Ruda 9.

Next, in the second stage, the carbonaceous material is discharged from the discharge port 8 of the fluidized bed 5, preheated iron ore is charged from the charging port 6, and then the gas stored in the gas holder 9 is transferred to the Then, the gas was allowed to flow into the fluidized bed 5 through the shutoff valve 3a, and a part of the gas was combusted in a partial combustion furnace (not shown) to raise the gas temperature to 1100° C. or higher.

The heated gas enters the fluidized bed 5, raises the temperature of the iron ore, and reduces it. The reduction time is approximately 30 minutes to utilize the time during the blowing time of the converter I. After reduction, the iron ore is discharged from the discharge lower.

The material balance and energy balance in the above examples will be explained as follows.

A) Material balance■ Generated gas amount Oxygen injection amount in a 5 ton converter: Approximately 21 Ngo/min x 12 minutes = 252 Ngo 02 The amount of CO generated is from C + O2 = co, 252X2 = 504 Ngo CO Actually In this case, the reaction of CO+ 3'202 = C02 occurs due to air intake from the top of the furnace and excessive oxygen injection, and as a result, the amount of gas generated is approximately as follows on average.

Co: 478N 85% CO2: 27N 5% N2: 55Nm'' 1O% Total: 56ONm'' = 46N/min However, when propane is used to protect the bottom blowing tuyere, H2 and H20 are present. The temperature of the generated gas is approximately 1
Although the temperature is as high as 600°C, the generation time is short, so if the iron ore is reduced at the same time, a) the iron ore will be locally heated, sintered, and melted.

口) Because the gas generation time is short, the iron ore reduction time is insufficient.

■ Ore amount Generally, the reduction reaction is carried out using the following formula.

The components of Fe203 +3CO=2Fe+3CO2 iron ore are: T, Fe: 68.3% by weight Fed: 0.39% by weight A203: 0.79% by weight 5i02: 0.73% by weight. Therefore, the iron balance is , 159.7 kg-F203 /67.2Nrn'-C
0→1136kg-F203 /47gNm''-〇〇The F2O3 in the ore was about 91% by weight, so -+12
48kg-0re/478N go CO or CO is 100
%, it is possible to reduce 1248 kg-0re 100%, but in reality, due to the partial combustion of co in the second stage and the limitation of the Co/CO2 ratio in the gas after the reduction reaction, the amount of ore processed and the reduction rate reached are limited. This was smaller than the theoretical value, and we were able to achieve a reduction rate of 52% for 51 kg of ore.

B) Energy balance (1) Process of converting converter generated gas with coke CO2 in the gas is converted with coke C according to the first-order equation.

CO2 + C = 2CO 22,4N Go + 12 kg → 44.8 N Since the C content in Go coke is 88% by weight, 12 kg-C is 1
3.6kg-Cake, (13,6kg-Coke/22-4Nrtf)X27
Nrr+”=16.4kg-Coke In other words, theoretically 16.4kg-Coke will be consumed,
Since the metamorphosis reaction occurs on the surface of the coke, a larger amount of coke is actually required.

(Input 8) The usable sensible heat of the generated converter gas is 0.35k
cal/Nm"-"C X56ONrn'X (1066-1000)"0=1
The energy required for metamorphosis is 17,600 kcal (heat output).

CO2+C=2CO 920k c a l/Nrn"-C0(27Nrn'
-CO2/22.4Nrrl”-CO2)X920kc
al/Nrn''-C0 = 1109 kcal (output, %) Heat amount of heating coke, To heat the residual heat temperature from the previous metamorphosis to 700°C and the reaction temperature to 1000°C.

(0,3k cal / kg g”o)X (10
00-300)'O − (
51 X 0.293

Co: 451Ntn' CO2: 79Nrn' N2: 55N Total: 585N The amount of heat generated is 3000kcal/Nrn" -〇〇×77NGoC
O = 231000 kcal (input 8) Heat of reduction reaction of iron ore 6.1 kcal/mo 1e-Fe2 o3X402k
gX0.97/159.7 = 14894 kcal (Heat output) Temperature rise of iron ore 0.213 kcal/Nrn"CX 585 N
m″×900°C = 174038 kcal (Heat output) Heat loss and others are almost the same as the heat loss and others in A) (1) above, which is 16199 kcal.

〔Effect of the invention〕

This defense has the following effects.

(1) Obvious recovery of converter exhaust gas by gas conversion and ore reduction.
It can be used in stages, significantly improving usage efficiency.

(2) It is possible to take the reduction reaction time of the fluidized bed reduction furnace without being restricted by the blowing time of the converter.

[Brief explanation of the drawing]

FIGS. 1 and 2 are process diagrams of an embodiment of the present invention. l... Converter 2... Oxygen for blowing 3...
Shutoff valve 4...Pipeline 5...Fluidized bed
6...Charging lower, 8...Discharge port

Claims (1)

[Claims] 1. A step of charging carbonaceous material into a fluidized bed, introducing converter exhaust gas into the fluidized bed, converting CO_2 and H_2O in the converter flue gas with carbonaceous material, and then storing it, and raising the temperature of the stored gas. A method of utilizing converter exhaust gas, comprising the step of reducing powdered iron ore by introducing it into a fluidized bed charged with powdered ore.