FR2489366A1 - DESULFURIZATION PROCESS DURING THE PRODUCTION OF GAS IN AN IRON BATH REACTOR - Google Patents

Abstract

THE INVENTION RELATES TO A PROCESS FOR DESULFURATION DURING THE PRODUCTION OF GAS IN AN IRON BATH REACTOR, THE INTRODUCTION OF THE REACTION ELEMENTS BEING CARRIED OUT FOR THE FUEL IN SOLID AND OR LIQUID FORM BELOW THE BATH SURFACE IN THE MASS MELTED IRON AND FOR OXIDIZING GAS, FOR EXAMPLE OXYGEN, OXYGEN ENRICHED AIR OR SINGLE AIR, BELOW OR WELL ABOVE AND BELOW THE SURFACE OF THE IRON TUB , CHARACTERIZED BY THE FACT THAT MILK OBTAINED IN THE MANUFACTURING OF STEEL, AS DESULFURATION MILK, IS INTRODUCED INTO THE IRON BATH REACTOR.

Description

The present invention relates to a desulfurization process.

  tion of gas production in an iron bath reactor, the introduction of the reaction elements being carried out for the fuel in solid and / or liquid form below the bath surface in the mass of molten iron and for the oxidizing gas, for example oxygen, oxygen-enriched air or simple air, below or above and below the

surface of the iron bath.

  Methods are known for reacting combustibles.

  tibles, especially coal, along with oxygen or

  gases containing oxygen in an iron bath and to pro-

  mute a reaction gas which consists essentially of CO and

  H2. A particular advantage of generating gas in a reaction

  iron bath consists in that the sulfur existing in the

  fuel is mainly absorbed by a slag.

  German patent application 25 20 883 describes a process for the continuous gasification of coal or fuels

  containing carbon in an iron bath reactor, according to-

  which fuels and oxygen, or gases containing oxygen, the latter being enveloped by hydrocarbons, are introduced via nozzles into the molten metal below the surface of the bath. The trainers of

  dairy, preferably lime dust with or without in-

  limestone or dolomite corporation, are entrained by the oxygen current or are blown into the bath under the

  forms a mixture with finely powdered charcoal.

  In German patent 25 20 584, a process is described.

  coal gasification die containing sulfur in a reaction

  iron bath, according to which part of the slag contains

  The sulfur is discharged continuously in the li-

  which is desulphurized and is recycled to the liquid state in the

  iron bath reactor. This process has proven to be particularly advantageous.

  with regard to the heat balance during the gasification process. The known methods represent different means for gasifying carbon-containing fuels in an iron bath reactor and they then produce reaction gases which are practically free of sulfur. All known processes use lime or limestone, possibly mixed with MgO or dolomite, to create a slag acting in a direction of desulfurization. The use of lime as a slag former, however, has a double disadvantage. On the one hand the expenditure in lime is high and on the other hand the lime must be heated to the temperature of the bath. For example, to gasify a tonne of coal, approximately 100 kg of CO having a sulfur content of approximately 1% must be added. The price of a ton of lime dust is currently around 250 F. and, to heat this lime, energy costs are also around F. When using less expensive limestone , the energy costs for heating and deacidifying the reactor at

  iron bath are so high that this procedure is economical-

even more unfavorable.

  The object of the invention is therefore to provide a pro-

  which allows to carry out the desulfurization, during the gasification

  coal fication in an iron bath reactor in a way

particularly profitable.

  According to the invention, this object is achieved by using a slag as a desulfurization slag in the iron bath reactor.

  steelworks obtained in the manufacture of steel.

  The addition of steel slag can be carried out in different ways in the iron bath reactor. The slag can for example be poured in pieces on the surface of the bath

  of iron or it can be injected in powder form in-

  below and above the surface of the bath in the iron bath reactor. Powdered slag can also

  be mixed with fuel, for example carbonated carbon.

  In a particularly advantageous and economical manner, the steel slag can be introduced as a basic support for the desulphurization in the vessel of the iron bath reactor, in the state as hot as possible and in particular in the liquid state. This procedure can be used in a particularly simple way

  when installing an iron bath reactor for gasification

  coal cation at a short distance from a steelworks. This is particularly the case in a metallurgical plant with an integrated power plant. In the power plant, it is possible to burn the gas produced by the process according to the invention in the boilers. When using steel slag in accordance with the present invention, significant costs are saved because this slag, which generally has a possibility of application

  limited, is available at low cost. Furthermore the best ex-

  Another advantage of using this slag is that it acts as a desulphurization slag in the bath reactor.

  iron and that it changes the composition of the coal ash.

  Indeed, these ashes then have a composition similar to that of conventional slag from blast furnaces and it is possible to treat them later, like these slag, in industry

  cement or building materials.

  The slag obtained in a steelworks, for example during the refining of a pig iron poor in phosphorus by the various refining processes in converter operating with oxygen, has approximately the following composition: 50% CaO, 10% SiO2 ,% FeO, 0.1% S, the residual constituents being essentially

  consisting of A1203, MgO, MnO and P205.

  The process according to the invention for desulfurization during the production of gas in an iron bath reactor uses this slag because its initial sulfur content, which is about 0.08 to 0.12%, is low because it thus has a high sulfur absorption capacity up to contents of around 10%. It is advantageous to limit the sulfur content of the slag to around 3% because it then remains in the field of blast furnace slag

  conventional and can be used in a similar way.

  The use of steel slag, for example from a steel production converter, for desulphurization in an iron bath reactor, also offers the advantage that the iron oxide content of these slags can be reduced and that

  thus additionally obtains iron in the installation of

  zeification. This iron can be taken fractionally from partix

  of the iron bath reactor and it can be recycled in the installation

  lation of steel production. Thus the use of a

  iron bath has advantages, for example for gasification

  cation of coal in a metallurgical plant.

  The method according to the invention makes it possible to fix the sulfur,

  contained for example in an almost complete carbonating coal-

  ment in the metallurgical slag which forms on the iron bath in the gasification plant. The sulfur content of the gases produced is very low. It is of the order of approximately ppm. It is thus possible to incorporate more than 99% of the sulfur

slag.

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  The use of the process according to the invention offers particular economic advantages when it is necessary to gasify qualities of coal containing high sulfur and ash contents. If, as was conventional until now, lime was added to form the slag, it would be necessary to use such high amounts that the process would no longer be profitable and furthermore it might be necessary to introduce additional lime. energy in the bath because these qualities of coal can no longer be gasified autothermally from

  made up of the large amount of lime needed.

  It is within the scope of the invention to introduce

  water in the iron bath reactor to increase the concentration

  hydrogenation of the product gas. Advantageously, during the

  gasification of energy-rich grades of coal, for-

  which the gasification process takes place with excess of

  energy, the free heat given off can be used to dissociate water into hydrogen and oxygen. While hydrogen is released from the molten metal bath, oxygen is reacted with

  carbon from the iron bath to form CO.

  The addition of water can be carried out directly in liquid form or also in the form of vapor. Obviously he

  it is also possible to introduce it in the form of a scram

  bacon in suspension with a carrier gas. In addition, we can also

  mix it with charcoal to carbonate or introduce it with charcoal by increasing its moisture content. For example, it has proved advantageous to introduce the coal without drying with a constant water content or else to condition the carbon to be gasified so that it is only partially

  dried in order to maintain a certain degree of humidity, with the-

  which coal is then introduced into the iron bath of the tank

of reaction.

  The use, in accordance with the present invention, of steel slag for the desulfurization during production

  of gas in an iron bath reactor thus proves particular-

  advantageous and economical from several points of view. This slag is well suited, because of its composition, as desulfurization slag for the gasification of coal and, on the other hand,

  when it is introduced in liquid form into the gas mass

  proud, it also saves energy that would be

  very necessary for the heating of the slag formers.

  In addition, the composition of the steel slag, after its use

  tion in the reactor in an iron bath, is modified so that it is suitable for use in the manufacture of cement and construction products. In addition to the economic advantages thus obtained, the problem of storage and the difficulties resulting from unusable slag are eliminated. The iron oxide content of the steel slag is reduced in the iron bath reactor and cast iron is obtained which can be converted

steel in the steelworks.

  The desulfurization process according to the invention used during the production of gas in an iron bath reactor proves to be particularly advantageous during the gasification of conventional grades of coal or of fuels containing carbon when liquid slag is used. creating an energy saving because there is then a greater quantity of energy to reduce the iron oxide in the iron bath reactor. In the context of the present invention, the advantage is also obtained of being able to use the excess energy to recover

  iron from iron ore or pre-

reduced.

  An iron bath reactor can be operated by

  applying the present invention for example in the following manner

  boasts: in a tank similar to a converter and having an internal volume of approximately 150 m3, 120 tonnes of liquid iron having a carbon content of approximately are initially introduced

  4%. In addition, 30 t of liquid slag obtained by the pro-

  sold LD. In this iron bath reactor, gasification is carried out.

  cation of approximately 50t per hour of coal having the following composition: C = 78.3%, Hz = 5.0%, 2 = 6.7%, ash = 5.0%, power: calorific Hu 7510 Kcal / Kg . Coal is introduced below the surface of the bath and is gasified with oxygen which

  is also blown through the bottom of the reactor. Simulta-

  In addition, 30 t of ore can be introduced per hour, for example

  ple in the form of a finely powdered ore, by nozzles placed at the bottom of the converter or else under the

  ore in pieces or pellets from the top of the container

  greenizer. After an operating period of 4 hours, about 50 t of slag and 210 t are obtained in the converter.

  of iron with a carbon content of about 2%.

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  At this time, remove all the slag and about 90 t of iron from the converter if possible. After a new addition of liquid LD slag, using the quantity

  above, the operation is continued as described. above.

  The gas produced is transferred to a gasometer for use.

  subsequent sation. The capacity of a conventional gasometer is generally

  sufficiently large to be able to supply the subscribers during the period of interruption necessary for the removal of the slag and steel and for the introduction of the new quantity of slag, this period amounting in total to approximately min. Liquid iron from the coal gasification reactor has a sulfur content of about 0.3% and a phosphorus content of about 0.1%. After desulphurization, we can

  subject in a known manner, for example in a conversion

  weaver, a refining operation to transform it into steel.

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Claims (13)

  1. Desulfurization process during the production of gas in an iron bath reactor, the introduction of the reaction elements being carried out for the fuel in solid and / or liquid form below the bath surface in the mass of molten iron and for the oxidizing gas, for example oxygen, oxygen-enriched air or simple air, below or   well above and below the surface of the iron bath, characteristic   terrified by the fact that it is introduced into the iron bath reactor,   as desulfurization slag, slag obtained in the manufacture tion of steel.   2. Method according to claim 1, characterized in that the steel slag is transferred to the iron bay reactor in the warmest possible state, in particular in the liquid state.   charge by charge or continuously.   3. Method according to claim 1, characterized in that the steel slag is blown in powder form below and / or above the surface of the iron bath found in the reactor.   4. Method according to any one of claims 1   and 3, characterized in that the steel slag is poured out   in pieces on the surface of the iron bath.   5. Method according to any one of the claims   1 to 4, characterized in that the steel slag has approximately the following composition: 50% CaO, 10% Sio2,% FeO, 0.1% S, the residual constituents being essentially consisting of MnO, A1203 and MgO.   6. Method according to any one of the claims   1 to 5, characterized in that the basicity (CaO / SiO2) of   steel slag is between 3 and 5.   7. Method according to any one of the claims   1 to 6, characterized in that the desulfurization slag is modified in the iron bath reactor by the ash from   fuels up to a basicity of 1 to 2.   8. Method according to any one of the claims   1 to 7, characterized in that the desulphurization slag in the iron bath reactor has a content   final sulfur which is at most 10%, preferably lower less than 3%. -8-   9. Method according to any one of claims 1 to   8, characterized in that water and / or water vapor is introduced into the iron bath reactor below the surface of the bath.   10. Method according to claim 9, characterized in that the water comes from the moisture contained in the coal introduced as fuel.   11. Method according to any one of the claims   1 to 10, characterized in that iron is produced by reduction of the iron oxide fraction contained in the steel slag   introduced into the iron bath reactor.   12. Method according to any one of claims   1 to 11, characterized in that the reduction of iron ore and / or pre-reduced iron ore is carried out in the reactor in an iron bath.   13. Method according to any one of the claims   1 to 12, characterized in that liquid iron is taken charge by charge and / or continuously from the reactor in a bath of   iron and in that it is introduced into a production facility tion of steel.