JPS5919965B2 - Fluid reduction method for iron ore that simultaneously produces reduced iron and fuel gas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to producing reduced iron by a fluidized reduction method of iron ore, which uses thermal medium particles and reducing gas in a circular manner and also directly uses coal as a reducing agent. It also relates to a method for producing gas.

In the fluidization reduction method in which iron ore and coal are directly introduced into a reduction reaction tower, the reduction reaction due to direct contact between iron ore and coal is an endothermic reaction, and the temperature is relatively high (850°C or higher).
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Since the reaction is delayed, it is necessary to consider an effective method of supplying heat to the reduction reaction column.

One solution to this problem is to install a combustion reaction tower in addition to the reduction reaction tower, supply coal, oxygen, and steam to the combustion reaction tower to perform combustion and gasification reactions, Coal and coke particles heated to a high temperature, that is, heat carrier particles, are fluidized and transferred to the reduction reaction tower to supply a predetermined amount of heat, and then returned to the combustion reaction tower, heated, and then supplied to the reduction reaction tower again. Another method is to circulate heat carrier particles.

At the same time, after purifying the gas generated from the reduction reaction tower and the gas generated from the combustion reaction tower, the generated gas is circulated and used in the reduction reaction tower so that it is heated and supplied to the reduction reaction tower again as a high-temperature reduction gas. Methods have also been implemented in which the heat and reducing gas are part of the supply.

The gas generated from the reduction reaction tower and the gas generated from the combustion reaction tower can be recycled to the reduction reaction tower as reduction gas, and contain hydrogen, carbon monoxide, and hydrocarbon gas, and have approximately 2000 to 3500 Kcal. As a medium calorie gas with a calorific value of /Nm'', it is an extremely high value-added gas.

In addition, in the reduction of iron ore using coal directly, the partially reduced iron ore has an extremely catalytic function for coal gasification, and coal gasification proceeds efficiently.

Therefore, in the present invention, in addition to producing reduced iron.

We will actively evaluate the aspect of coal gasification as a fuel gas production method.

In other words, using coal as a raw material. The gas generated by coal gasification during fluidized reduction is in a reducing atmosphere, so the sulfur in the coal mainly turns into hydrogen sulfide.2 The gas can be easily cleaned by desulfurization, making it extremely clean. It becomes a fuel gas.

Therefore, if the present invention is applied to coal, which is difficult to use due to air pollution, it will be possible to produce reduced iron as well.
Fuel gas can be efficiently produced.

Therefore, in order to produce reduced iron that satisfies predetermined properties and to produce fuel gas that satisfies a predetermined calorific value, the production amount of fuel gas and the production amount of reduced iron using circulating gas must be adjusted accordingly. is extremely difficult to operate.

Therefore, in the present invention, as a simple means to arbitrarily control the production amount of reduced iron and fuel, we have devised a method of adjusting the amount of coal supplied to each of the reduction reaction tower and the combustion reaction tower.

The present invention will be explained below with reference to the drawings.

FIG. 1 shows a fluidized reduction apparatus used for fluidized reduction of iron ore by the heat medium particle circulation method and production of fuel gas by gasification of coal.

This apparatus mainly consists of a reduction reaction tower 1 and a combustion reaction tower 2, and iron ore is introduced into the reduction reaction tower 1 through a feed port 3 via a feeder (not shown).

Coal is introduced from supply port 4.

The reduction reaction tower 1 and the combustion reaction tower 2 are connected via a connecting pipe 9, and heat carrier particles generated in the combustion reaction tower 2 are fluidly transferred into the reduction reaction tower 1 through the connecting pipe 9. The system provides the necessary amount of heat and performs fluidization reduction and gasification of the coal.

In addition, a circulating gas obtained by refining a part of the gas generated by the apparatus is supplied into the reduction reaction tower 1 through a gas supply port 5, and this circulating gas fluidizes the iron ore and heat transfer medium particles to cause a reduction reaction. While the reduced iron particles generated after the completion of the reaction are discharged from the lower outlet 8 of the reduction reaction tower 1, the heat carrier particles are
The fluid is transferred into the combustion reaction tower 2 via the connecting pipe 10 and the cyclone 11.

On the other hand, coal, which becomes heat carrier particles, is supplied into the combustion reaction tower 2 via a feeder (not shown) via a feeder lower.

Furthermore, oxygen or a gas containing oxygen is supplied into the combustion reaction tower 2 through the supply port 6.

If necessary, a part of the circulating gas or steam may be supplied as the fluidizing gas.

The combustion residue (ash) is discharged from the outlet 12 of the combustion reaction tower 2.

In this way, the heat carrier particles are fluidized and circulated between the two towers while being heated to a high temperature (850°C or higher) in the reduction reaction tower 1.
forming a fluidized bed, gasifying coal to produce fuel gas while reducing iron ore, and reacting coal and oxygen while heating heat carrier particles in the combustion reaction tower 2;
Manufacture fuel gas.

The gas generated at the top of the reduction reaction tower 1 through the fluidized reduction and coal gasification reactions described above is transferred to the connecting pipe 10. Via the cyclone 11, it joins with the combustion reaction tower top gas at the upper part of the combustion reaction tower 2, and is discharged from the tower top outlet 13, to a gas purifier 14 including a desulfurization device. It passes through the cooling purifier 15 to be cleaned and cooled.

The cleaned exhaust gas is then divided into portions to effectively utilize hydrogen, carbon monoxide, and other gases that have reducing ability.1. After boosting the pressure with the gas booster 16, if necessary, shift converter 17 dehydration and decarbonation device 1
After being converted into a circulating gas having a high content of hydrogen and the like through step 8, the circulating gas is introduced into a circulating gas heater 19 in order to be heated to a high temperature of 850° C. or higher, and then mainly introduced into the reduction reaction tower 1 through the supply port 5.

Note that part of the gas generated at the top of the tower may be used as the circulating gas heater gas.

As mentioned above, the feature of the present invention lies in the manner in which the generated gas having an effective gas component is used and its controllability.

That is, the gas generated at the top of the tower other than that used for circulating gas is 2000 to 3500 Kcal/Nm as shown in the figure.
It is taken out of the system as a medium-calorie fuel gas and used for other heating processes.

Of course, it is also possible to convert the fuel gas into synthetic natural gas (methane-rich gas) and increase its heat by processing the fuel gas using the gas converter 20 or the like as necessary.

Next, in the present invention, it will be explained how to adjust the production amount of reduced iron and the production amount of fuel gas as appropriate.

In general, reduced iron production plants are overwhelmingly advantageous in terms of effective use of heat, when used as part of a system that combines the process of melting and refining the produced reduced iron, or the ingot rolling process. It is.

In such cases, two steps are required in the process after reduced iron production.
The process necessarily includes a heating process, and the fuel gas produced simultaneously with the production of reduced iron according to the present invention can be used very effectively in the heating process.

Compared to such fuel gas, in the case of directly burning coal, there are many disadvantages as the combustion machine becomes more complex and additional equipment such as desulfurization, denitrification, and dust treatment increases.

Now, the fuel gas used in the process after producing reduced iron is 2000K cal/Nm as a general usage condition.
It is desirable to have a calorific value greater than or equal to the amount of heat generated.

600 Nm3/ - reduced iron or more is desirable.

In other words, if the extraction amount is extremely small, it is of little significance for fuel gas production, and considering that a calorific value of about 1 million to 1.2 million K cal / t is one standard value in the process after reduced iron, 60ONTrL3 / l was taken as the lower limit.

Furthermore, it is not preferable to produce a fuel gas with a concentration of 100 ONm3/ - reduced iron or more in order to produce reduced iron so as to ensure a predetermined quality (reduction rate of about 70 to 95%) in the reduction reaction tower.

Therefore, in the present invention, under the conditions that while producing reduced iron that satisfies the quality with a reduction rate of about 70 to 95 tatami mats, at the same time producing fuel gas with a calorific value of 2000 Kcal/Nm3 or more, The method of reducing the amount of fuel gas produced per reduced iron from 600 to 10,100 ON per reduced iron is carried out by adjusting the coal supply amount as described above.

In other words, the amount of fuel gas produced by reduced iron Douga is X (
Nm3/ is one reduced iron), and out of the amount of coal supplied,
If the ratio of the amount of coal supplied to the reduction reaction tower is Y, then the second
As shown in the figure, 600≦X≦1000 1.25X10
'X10.275≦Y≦1.25 X10'X+0
．． The amount of coal supplied to each of the reduction reaction tower and the combustion reaction tower is adjusted within a range that satisfies 475'.

Here, FIG. 2 shows the simultaneous production of reduced iron having a predetermined quality and fuel gas having a predetermined property.
This diagram shows the relationship between X and Y.

Therefore, a part of the gas generated by the reducing device was heated to 2000K c
In order to produce reduced iron of a prescribed quality in a reduction reaction tower after taking out a fuel gas with a l/N of 7713 or more, the amount of iron ore supplied is equal to the amount of coal supplied.

It is necessary to appropriately select many operating variables such as the amount of circulating gas, and the operation is extremely complicated and difficult to adjust, which can lead to situations where reduced iron or fuel gas that is unsuitable for production has to be produced. encounter.

For example, in Figure 2, if the operation is carried out at a point like the point marked Δ, the reduction rate of the produced reduced iron will decrease, which is disadvantageous, and if the operation is carried out at a point like the point marked X, the reduction rate of the produced reduced iron will be disadvantageous. The calorific value of the fuel gas decreases, making it extremely inconvenient to use as a commonly used fuel gas.

Therefore, by using the relationship shown above and making fine adjustments within the range shown in the figure while detecting the components of the generated gas, it is possible to easily achieve the desired objective.

That is, the amount of fuel gas produced is determined with respect to the amount of reduced iron produced, and the coal supply ratio Y is set to the median value in the figure according to FIG.

While considering the quality of the coal used, the quality of the ore, the gas composition at the top of the reduction reaction tower, the gas composition at the top of the combustion reaction tower, the reduction rate, etc., which are based on factors such as the quality of the coal used, the quality of the ore, the temperature of the reduction reaction tower to the temperature of the combustion reaction tower, etc. Make fine adjustments within the shaded area.

EXAMPLE A test of fluidization reduction and simultaneous production of fuel gas by one method of the present invention was conducted using a reduction apparatus as shown in the drawings.

The manufacturing conditions and test results are shown below.

■, Iron ore brand MBR Ore TFe
65% Grade (Fe00.6% Gangue 2.4% Particle size 2mm or less Supply rate 1.15 t/hr2, Coal brand Warkworth coal (F, C, 58% Grade V, M, 36% Gangue 7) % Particle size 1 mm or less Amount supplied to the reduction reaction tower 0.289 t/hr Amount supplied to the combustion reaction tower 0.224 t/hr Amount supplied to the reduction reaction tower 56% Coal per 1 iron ore supplied Supply amount: 0.45 t/t 3, Oxygen supply amount to the oxygen combustion reaction tower: 269 Nm3/hr4, Reduction device top gas emission amount: 135 ONm3/hr Composition H2: 37% H20: 10% CO: 34% CO2 : 16th section CH4, etc. = 3rd section Temperature 950°C 5. Amount of circulating gas supplied to the circulating gas reduction reaction tower 521 Nm3/hr Circulating gas temperature 950°C Gas composition H2: 96% CO2: 1% CH4: 3% 6. Reduction device operating temperature Reduction reaction tower: 920°C Combustion reaction tower: 1010°C 7. Reduced iron' production amount: 0.792 t/hr Reduction rate: 91% Particle size: 2 iron or less 8. Fuel gas production amount: 68ON7723/hr Gas composition H2: 41% CΩ: 37% C02: 18% CH4: 4% Calorific value 2510 Kcal//'Nm3 The effects of the present invention can be summarized as follows: fuel gas production amount/reduced iron production amount 85ONm3/.

■) In a system that produces reduced iron using coal, which is a valuable fossil fuel resource, and expensive oxygen.

As an effective use of the generated gas from the fluidization reduction device, the generated gas is used within the system as a circulating gas that requires reducing ability, while the
It can be used for heating processes outside the system as a medium calorie fuel gas of 500 m''.

2) Components such as sulfur in coal that are harmful when released into the atmosphere are in the form of hydrogen sulfide, which is easily desulfurized by a fluidization reduction device, and can be easily removed by a generated gas purification device. It is possible to produce fuel gas with less harmful effects such as air pollution, or circulating gas with less sulfur for reduced iron production.

3) In general, reduced iron manufacturing plants are used as part of a system that combines the process of melting and refining the manufactured reduced iron, or the ingot making/rolling process, which is overwhelming in terms of effective use of heat. There are many.

In such cases, steps such as heating are necessarily included in the process after producing reduced iron.

Therefore, according to the present invention, it is possible to produce reduced iron, as well as to clean it.
The present invention is extremely valuable for the above-mentioned system because it is easy to use and can produce fuel gas with a high calorific value.

4) Controlling the amount of reduced iron production and fuel gas production while ensuring the specified quality was an extremely difficult operation, but it was possible to adjust the amount of coal supplied to the reduction reaction tower and fuel reaction tower. By doing so, the control can be easily performed to the desired set value.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal section showing an example of a fluidization reduction device used to carry out the method of the present invention, and a schematic diagram showing a method of utilizing gas generated in the reduction device. 1... Reduction reaction tower, 2... Combustion reaction tower, 3... Iron ore supply port, 4... Coal supply port, 5... ...Circulating gas supply port, 6...
Oxygen, steam supply port, 7...Coal supply port, 8.
...Reduced iron discharge port, 9,10...Connection pipe, 11...Cyclone, 12...Combustion residue discharge port, 13... Generated gas outlet, 14.
...Gas purifier, 15 Cooling purifier, 16...
...Gas booster, 17...Shift converter,
18... Dehydration, decarbonation device, 19...
...Circulating gas heater, 20... Gas transformer. Figure 2 (1. X
It is a chart showing the relationship between (fuel gas production amount N m3 per reduced iron production amount) and Y (coal amount t supplied to the reduction reaction tower per total coal supply amount).

Claims (1)

[Claims] 1. Iron ore, coal, and heated reducing gas are supplied to the reduction reaction tower, and the combustion reaction tower is supplied with iron ore, coal, and heated reducing gas. Charcoal material such as coal or coke, oxygen or oxygen-containing gas, and if necessary steam are supplied to combust the carbon material to generate a flow of carbon material and heat carrier particles, and reduce the heat carrier particles. In a method of performing fluidized reduction of iron ore in the reduction reaction tower by circulating the iron ore to both reaction towers through a communication pipe provided between the reaction tower and the combustion reaction tower, the reduction reaction tower and the combustion reaction tower are The gases generated in each are combined and taken out, a part of the taken out gas is supplied to the reduction reaction tower as a reducing gas, this part of the gas is circulated within the system, and the remaining gas is When feeding gas outside the system as a fuel gas, the amount of coal supplied to each of the reduction reaction tower and combustion reaction tower is adjusted to satisfy the following formulas (1) and (2). It is characterized by controlling the amounts of both reduced iron and fuel gas. A method for simultaneously producing reduced iron and fuel gas by circulation of heating medium particles and reducing gas, and by the fluidized iron ore reduction method using coal. 600≦X≦1000 ・・・・・・・・・・・・・・・
...(1) 1.25X10'X+0.275≦Y≦1
．． 25X104X+0.475
・・・・・・・・・・・・・・・(2) However. X: Out of the gas generated by combining the gases generated in each of the reduction reaction tower and the combustion reaction tower and taken out, the amount of fuel to be sent outside the system and the amount (Nm) per 11 reduced iron produced. /t) Y: Ratio of coal supply amount to the reduction reaction tower to total coal supply amount