JPS5850292B2 - Fluidization reduction method for iron ore using circulation of heat carrier particles and reducing gas, coal and air - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention burns carbonaceous materials such as coal and coke with air to generate heating medium particles, and circulates and uses the heating medium particles and reducing gas, and further uses coal as a reducing agent. This relates to a method for fluid reduction of iron ore for direct use.

Conventionally, various methods have been put into practical use as methods for reducing iron ore, but new methods are desired in order to cope with future constraints from energy, resources, the environment, etc.

Regarding the shape of iron ore, it is expected that the proportion of fine ore will increase, and it is necessary to develop an effective reduction method for fine iron ore.

One of these methods is the fluidization reduction method, in which iron ore and coal are directly introduced into a reduction reaction tower. If the temperature (850° C. or higher) is not maintained, the reduction reaction will be delayed, so it is necessary to consider an effective method of supplying heat to the reduction reaction column.

One solution to this problem is to supply carbonaceous materials such as coal and coke to the combustion reaction tower, combust them using air, generate high-temperature carbonaceous materials, or heat transfer particles, and flow them into the reduction reaction tower. After being transferred and supplying a predetermined amount of heat, it is returned to the combustion reaction tower, heated, and again supplied to the reduction reaction tower.

The heating medium particle circulation method is effective.

The gas generated in the reduction reaction tower at this time contains components effective for reduction, so it is possible to recycle it by heating it after purification and supplying it to the reduction reaction tower again, and it can also be used as a fuel. It is also possible to extract it as a gas.

However, since air is used in the combustion reaction tower, it is difficult to separately use the gas generated by the combustion reaction tower as a fuel gas. In doing so, consideration must be given to ensuring that the gas generated by the combustion reaction tower does not contain unburned gases such as carbon monoxide and hydrogen that have a calorific value as much as possible.

Therefore, in connection with the above points, the present inventors propose a method of combustion of carbonaceous material using an effective air supply means in a combustion reaction tower.

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

FIG. 1 is a schematic diagram of the equipment and the utilization form of the generated gas for the fluidization reduction of iron ore using heating medium particles and the reducing gas circulation method and the fuel gas production method by gasifying coal.

The fluidization reduction apparatus is composed of a reduction reaction tower 1 and a combustion reaction tower 2. Iron ore is introduced into the reduction reaction tower 1 through a feeder (not shown) through a feed port 3, and coal is introduced into the feed port 4. Introduced from.

The reduction reaction tower 1 and the combustion reaction tower 2 are connected through a communication pipe 9, and heat carrier particles generated in the combustion reaction tower 2 are fluidly transferred into the reduction reaction tower 1 through the communication pipe 9. Then, the required amount of heat is applied to perform fluidization reduction and gasification of the coal.

Further, a circulating gas obtained by purifying a part of the gas generated in the reduction reaction tower is supplied into the reduction reaction tower 1 through the gas supply port 5,
The circulating gas fluidizes the iron ore and heat carrier particles, and the reduced iron particles generated after the reduction reaction is discharged from the lower outlet 8 of the reduction reaction tower 1, while the heat carrier particles are discharged through the connecting pipe 10. , and transferred into the combustion reaction tower 2.

The gas generated in the reduction reaction tower is washed and cooled through a gas purifier 14 including a desulfurization device and a cooling purifier 15.

This generated gas is a gas generated during the fluid reaction of coal and iron ore, and contains hydrogen, carbon monoxide, and hydrocarbons with reducing ability, and is pressurized using the gas booster 16 as outlined above. After that, if necessary, shift converter 1
7. After passing through the dehydration and decarbonation gas device 18, the gas is introduced into the circulation gas heater 19 to raise the temperature to 850'C or higher, and then introduced through the supply port 5 at the bottom of the reduction reaction tower 1. In addition to being used for circulating gas, the gas generated by the reduction reaction tower is
It is also possible to take it out of the system as a medium calorie fuel gas, as a raw material for methanol, or as a raw material gas for a wide variety of chemical industries, and use it as a product gas.

Of course, if the present fuel gas is processed using the gas converter 20 or the like at that time, synthetic natural gas (methane enriched gas) can be obtained.
It is also possible to increase the heat by converting to

As mentioned above, the reduction reaction tower uses coal and iron ore as raw materials,
Utilizing high-temperature heat carrier particles from the thermal sintering reaction tower described later,
It is possible to simultaneously produce reduced iron by reducing powdered iron ore and produce fuel gas by gasifying coal.

On the other hand, into the combustion reaction tower 2, carbonaceous materials such as coal and coke, which become heat carrier particles, are supplied from a feeder (not shown) through a supply lower, and air is supplied through a supply port 6.

If necessary, water vapor may be further introduced.

The supplied carbonaceous material is combusted in the air, becomes high-temperature heat carrier particles, and is transferred to the reduction reaction tower 1 via the communication pipe 9.

Further, the combustion residue is discharged from the discharge port 11 in the combustion reaction 2.

The combustion reaction tower exhaust gas is discharged from the exhaust port 13, and the exhaust gas treatment device 2
1 and then disposed of through the chimney 22.

Now, in order to heat the heating medium particles for supplying heat to the reduction reaction tower, the combustion reaction tower uses air to burn carbonaceous materials such as coal and coke that become the heating medium particles.

Therefore, since the combustion reaction tower generated gas essentially contains a large amount of nitrogen gas, it is not effective to use it as a fuel gas, and when carbonaceous material and air are combusted, carbon dioxide gas and water vapor cannot be completely combusted. As the temperature approaches, the amount of heat generated increases, so in the combustion method of carbonaceous materials that uses air, it is necessary to devise an effective method to carry out the combustion reaction under conditions close to complete combustion.

By the way, when carbonaceous material and air are combusted in a high-temperature fluidized bed at a temperature of 850°C or higher, the carbon dioxide and water vapor generated (
1), Reacts with the carbonaceous material again by the reaction CO2+C→2 CO(1) HO+C-+CO+H2(2) shown in equations (2) to produce carbon monoxide and hydrogen,
Since this reaction is endothermic, it becomes a factor that inhibits effective heat generation.

Therefore, in order to eliminate such inhibiting factors, the present invention provides a method in which air is supplied in two stages, upper and lower, when carbonaceous material is combusted with air in a combustion reaction tower that generates heat carrier particles. It is something to do.

First, the oxygen in the air that is blown in from the lower supply port 6, which also serves as a normal fluidizing gas, is combusted in the fluidized bed of carbonaceous material, producing carbon dioxide gas and water vapor, and as mentioned above, In the process of reaching the upper part of the fluidized bed, carbon monoxide and hydrogen are partially generated by the reactions shown in equations (1) and (2).

In order to combust this unburned gas such as carbon monoxide and hydrogen into carbon dioxide gas and water vapor, further air is supplied from the additionally installed supply port 6' in the upper stage at the same level as the air supply from the lower stage. .

The necessary conditions here are to secure the amount of air supplied to the lower stage 6 and the amount of air on the same place, and the amount of carbon material (M, t) filled and fluidized above the upper stage air supply port 6'. 6 against
Air supply amount from ′ (■.

Nrrl/hr) is V(Nm”/hr)〉x2so (3)-11possibler-
-- The amount of air supplied from the upper stage 6' is adjusted so as to satisfy the following.

Of course, if V/M is too large, the oxygen in the air will not be fully utilized, which is inappropriate, and it is economically undesirable to use a larger amount of air than necessary.

In other words, in the combustion of carbonaceous materials with air under the conditions shown in the relational expression (3) above, the time required for carbon dioxide gas and water vapor, which are quickly generated by oxygen in the air, to pass through the carbonaceous fluidized bed. (1) because is short.

The rate at which the reaction expressed by equation (2) occurs is extremely small, and the fluidized bed as a whole can carry out combustion reactions in conditions close to complete combustion, including carbon dioxide gas and water vapor.

In addition, since the amount of heat generated in this case is extremely small, it is necessary to supply a predetermined amount of heat to the heat carrier particles (thus, the reduction reaction tower is supplied with carbonaceous materials such as coal or coke supplied from the supply lower of the combustion reaction tower). The amount can be reduced, and the total air supply amount can also be reduced.

As mentioned above, if carbonaceous material is air-combusted under conditions other than the conditions shown in equation (3), a large amount of unburned gas such as carbon monoxide and hydrogen will remain in the gas generated by the combustion reaction tower, so the reduction reaction will be delayed. It is not effective for heating the heat carrier particles for supplying heat to the tower.

In addition, if the amount of air supplied from the lower supply port 6 of the combustion reaction tower satisfies equation (3) regarding the amount of carbon material filled and flowing above the supply port, then the air amount supplied from the upper supply port 6' It is not necessary to supply air.

EXAMPLE A test of the fluidization reduction method of the present invention was conducted using an apparatus as shown in the drawings.

The test conditions and test results are shown below.

1. Reduction reaction tower Iron ore brand MBR ore (Rejected 65% Quality 0016% 2.4% Particle size 2 or less Supply amount 730kg/hr Coal brand Warkworth coal ↓3, C058% Quality, M, 36% Stone 7% Particle size 1 mm or less Supply amount 150 kv/hr Circulating gas supply amount 720be/hr Temperature 948°C Composition H2:86%, H20: 3%, CO: 2%.

CO2: 3%.

CH4: 6% Fuel gas production amount 93rIVhr Composition H2nia 5%, CO: 16%.

C02: 4%, CI-(4: 5% Reduced iron production amount 482'q/hr r reduction rate
92.5% Particle size 2mr IL or less Reduction reaction tower Reaction temperature 933°C 2. Combustion reaction tower Coal brand Warkworth coal particle size 1 or less Supply amount 182 kg/hr r Air supply amount 1781 Nm'/hr From the upper stage Air supply amount 975 Nrrt/hr Filling above the upper stage air supply port, amount of fluidized carbonaceous material 0.6t 1625 Air supply amount from the lower stage 806 Nm/hr r Filling below the upper stage air supply port from the lower stage air supply port , the amount of fluidized carbon material 6.6 is burned in the reaction tower
Reaction temperature: 1031° C. The amount of fluidized carbon material was calculated by estimating the fluidized bed height etc. from the pressure measurement results at each height in the furnace.

In the above example, only the lower row has 1781 N771”/
When air is supplied for hr, V--1781=270, and M6. Because of this, a large amount of unburned carbon monoxide and hydrogen remain in the top exhaust gas of the combustion reaction tower, resulting in poor combustion efficiency.

As shown in the above embodiment, the upper air supply ports 6' to 9
When 75 N771"/hr is supplied, carbon monoxide, hydrogen, etc. are combusted, the calorific value is large, and the combustion efficiency is good.

The effects of the present invention can be summarized as follows.

1) Powdered iron ore can be used without agglomeration, so energy and raw materials for agglomeration are not required.
There is no generation of NOX, SOX, or dust associated with agglomeration.

2) Because air is used to manufacture high-temperature heat transfer particles,
It is possible to construct the entire system using powdered iron ore, carbonaceous materials such as coal, and air, which allows us to take an extremely advantageous position in terms of location, and even though air is used, there is no reduction Because the gas generated from the reaction tower and the combustion reaction tower are processed separately, it has the characteristic of producing a medium-calorie fuel gas that does not contain nitrogen.

3) Sulfur in coal, which is harmful when released into the atmosphere, is in the form of hydrogen sulfide, which is easily desulfurized when gasified, and can be easily removed with a purifying device.
It is possible to produce a fuel gas that does not cause air pollution or other problems, or a circulating gas that contains fewer harmful components such as sulfur for reduced iron production.

4) Since coal can be used directly for the reduction reaction, compared to general reduced iron production methods, there is no need for reducing gas production equipment, the system is simple, and it has great economic value.

5) In general, reduced iron production plants are overwhelmingly operated as part of a system that combines the process of melting and refining the produced reduced iron, or the ingot making/rolling process.

In such cases, a heating step is necessarily included in the process after producing reduced iron.

Therefore, according to the present invention, it is easy to use because it is clean, and it is possible to produce a fuel gas with a high calorific value as well as the production of reduced iron, so the present invention has great utility value for the above system.

6) In the combustion reaction tower, since carbonaceous materials such as coal are combusted with air, it is desirable to completely combust carbon dioxide and water vapor as much as possible.

In contrast, the present invention improves the combustion efficiency of coal by supplying air to the combustion reaction tower in two stages, the upper and lower stages. It is possible to lower the unit consumption.

[Brief explanation of drawings]

The drawings are 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 the 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, 6.6'...
...Air supply port, 7...Coal supply port, 8...
...Reduced iron outlet, 9.10...Connection pipe, 1
1... Combustion residue outlet, 12... Reduction reaction tower generated gas outlet, 13... Combustion reaction tower exhaust gas outlet, 14... Gas cleaning Vessel, 15...
... Cooling purifier, 16 ... Gas booster, 17
......Shift converter, 18...Dehydration, decarbonation gas device, 19...Circulating gas heater,
20...Gas converter, 21...Exhaust gas treatment device, 22...Chimney.

Claims (1)

[Claims] 1. Iron ore, coal, and heated circulating gas are supplied to the reduction reaction tower, while coal, carbonaceous materials such as coke, air, and, if necessary, steam are supplied to the combustion reaction tower. combust the carbonaceous material to generate heat carrier particles made of the carbonaceous material, and circulate these heat carrier particles to both reaction towers via a connecting pipe provided between the reduction reaction tower and the combustion reaction tower. In the method of fluidizing reduction of iron ore in a reduction reaction tower, in order to supply the above-mentioned air to the combustion reaction tower, two stages of upper and lower air supply ports are provided in the combustion reaction tower, and air is supplied from the upper stage supply port. The air supply amount (Nm'/hr) is placed on the plate equidistantly with the air supply amount (Nm'/hr) from the lower supply port, and the air is filled above the level of the upper supply port and flows. V/M≧1 between the weight of carbonaceous materials such as coal and coke (1)
280 (However, ■ is the amount of air supplied to the upper supply port (N
m'/hr), and M is the above carbon material weight (1). ] A method for fluidizing and reducing iron ore using circulation of heat carrier particles and reducing gas, coal and air, characterized in that air is supplied to a combustion reaction column so as to satisfy the following.