FR2488903A1 - PROCESS FOR PRODUCING GAS IN IRON BATH REACTOR - Google Patents

Abstract

THE INVENTION RELATES TO A PROCESS FOR THE PRODUCTION OF GAS IN AN IRON BATH REACTOR WHERE IS A LIQUID IRON BATH WHICH RECEIVES LIQUID OR SOLID FUELS CONTAINING CARBON AND ON THE SURFACE FROM WHICH IS PROJECTED A JET OF GAS CONSISTING AT LEAST PARTLY OF OXYGEN, THE FUELS BEING CARBONIZED IN THE FORM OF GAS WHICH ACCUMULATES IN THE CHAMBER PLACED ABOVE THE BATH SURFACE AND WHICH ARE EVACUATED FROM THIS CHAMBER. IT IS CHARACTERIZED BY THE FACT THAT THE GAS JET IS PROJECTED THROUGH THE SAID CHAMBER 30 ON THE SURFACE OF THE BATH 22 AND INSPIRES THE GAS PRODUCED WHILE CROSSING THE CHAMBER ENSURING THEIR PARTIAL BURNING AND THEIR TRAINING TO THE SURFACE OF THE BATH SUCH SO THAT THE HEAT PRODUCED BY THE COMBUSTION OF SAID GAS IS TRANSMITTED TO THE IRON BATH21.

Description

The present invention relates to a method for producing gas in a

  iron bath reactor is a bath of liquid iron which receives liquid or solid carbon-containing fuels and on the surface of which is blown a jet of gas consisting at least in part of oxygen, the fuels being gasified in the form of gas that is collected in the gas chamber above the surface of the bath and is removed from the

this room.

  It has already been known for a long time to continuously gasify coal or other carbon-containing fuels in an iron bath or steel bath reactor having a slag layer to form a gas consisting essentially of CO and H2. In the process of the German patent application DE-OS 29.52.434, an oxygen is applied to the surface by means of a lance placed above the surface of the iron bath. of the bath so as to create a blow zone at high temperature. In this high-temperature blowing zone, a solid powder containing carbon is sprayed with a carrier gas. In addition, according to the German patent application DE-AS 25 883, there is known a method according to which is infused into the iron bath coal or a fuel containing carbon in

  below the surface of the bath. Also the gas jet, is composed

  at least partly oxygen, is blown into the iron bath below its surface, a shell formed of hydrocarbons

  ensuring the protection of associated nozzles.

  Finally, according to German Patent No. 25.20.868,

  a process according to which is added to the additional iron bath

  It is also possible to use energy-rich coal, unbound carbon, aluminum, silicon, calcium carbide or mixtures, where appropriate independently of the coal to be gasified. We introduce

  thus heat in the coal gasification process.

  A disadvantage of these processes is that the gasification of bad fuels, including coal qualities low calorific heat could not be achieved

  until now profitably because they require the addition of

  energy-rich fuels to maintain the temperature of the iron bath with such fuels. Finally, with known methods, it is not possible to use gases

  inexpensive oxidantd, such as air for example.

  It is therefore an object of the invention to overcome the disadvantages of the known processes and to provide a process by which it is economically possible to produce from carbon-containing fuels and / or or hydrocarbons and being in a solid form, crushed or liquid, in an iron bath reactor, a fuel gas involving low energy fuels and using inexpensive oxidizing gases, which allows in particular

  avoid the addition of energy-rich fuels for the equi-

  libration of the thermal balance of the gasification process.

  This object is achieved in that the jet of gas is blown through the gas chamber onto the surface of the bath and sucks,

  when crossing the chamibre the gases produced, burning them

  partially and dragging them towards the surface of the bath so that the heat generated during the combustion of the gases

  products be transmitted to the iron bath.

  Thus the jet of gas passes through the gas chamber located at

  above the surface of the bath, traveling as far as possible. Under the action of the jet, the gas in the chamber and produced by gasification of the fuel is sucked and driven. This effect also occurs for example in the case of a water jet pump. Since the jet of gas directed towards the surface of the bath contains oxygen, a part

  combustible gases produced are burned. The heat thus engenders

  drée is transferred to the iron bath because the jet of gas deflects the hot combustion products to the surface of the bath so that they

  come in contact with it and can give up their heat.

  According to the invention, by projecting a gas jet formed of an oxidizing gas (oxygen, air or the like) onto the surface of the bath, it is possible to improve considerably

  the thermal balance in an iron bath reactor.

  The method according to the invention makes it possible to use air for the jet of gas. It is thus not necessary to use technically pure oxygen as in the known processes. Air is normally available inexpensively and can be compressed to the required working pressure with simple means. In this respect, it is particularly advantageous to

  Preheat the air so that you can avoid extracting

  gasification process the heat required to preheat the air. In practice, it has proved advantageous to adopt a

  preheating temperature of 300 to 4000C. Until this temperature

  In addition, conventional pipe and shutter members can be used and the thermal insulation of

  feeding can be achieved economically.

  Also it is however possible to use technically pure oxygen for the jet of gas. This is particularly advantageous in the case of fuels with very low calorific value. The fraction of oxygen contained in the jet of gas is thus determined essentially by considerations concerning

  the profitability and the quality of the fuels used.

  It is advisable to inject solid or liquid fuels into the iron bath below its surface. For transport, carrier gases such as air, nitrogen, carbon monoxide, an inert gas, etc. are used.

  however, it is also possible to get the fuel

above the surface of the bath.

  The oxygen contained in the jet of gas blown into the gas chamber and above the surface of the bath serves in particular to

  burn some of the gases produced from the fuel. Linen-

  On the other hand, oxygen production for the gasification process is advantageously carried out below the surface of the bath by means of nozzles. These consist for example of several concentric tubes and are used for the protection of

  nozzles outside, in a known manner, a hydrocarbon.

  The proportion of oxygen injected below the surface of the bath relative to the proportion of oxygen introduced into the jet of gas on the surface of the bath can be modified within undefined limits. For example, it is possible to introduce 80% of the total oxygen through the jet of gas arriving on the bath surface and to inject only 20% oxygen below the surface of the bath, or to operate exactly the opposite way by injecting 80% oxygen below the surface of the bath and into

  causing 20% oxygen to enter the jet of gas.

  However, it has been found that at least 10% of the total amount of oxygen introduced into the iron bath reactor must be blown with the jet of gas on the bath surface in order to exploit the advantages of the invention. as regards the calorific value. This percentage can be increased up to LOO%. In this regard, it has surprisingly been found that this oxygen of the gas jet serves for the oxidation of the fuel in the iron bath. For the conventional mode of operation of the iron bath reactor, about 40 to 90% of the total amount of oxygen is fed through the jet of gas. The proportion indicated above is already estimated as the highest possible for economic reasons because this proportion of the total quantity is generally insufflated at a pressure lower than that required for nozzles placed below the surface.

bath.

  Preferably, several throws of gas are directed to the surface of the bath. The insufflation is carried out at a considerable distance from the surface of the bath, the impact zone being located approximately in the middle of said surface. It is essential to have a fairly long path length of the gas jets in the chamber above the surface of the bath. Normally, a minimum distance of about 2 m must be maintained between the jet nozzles of the jet of gas and the surface of the bath. The nozzles are

  installed in the refractory lining in the upper part of the

  reactor. They can, mainly when insuffla-

  air, consist of a single tube or, as for example during the insufflation of technically pure oxygen, two concentric tubes. In the last embodiment, the oxygen flows into the central tube and, for the protection of the nozzles, nitrogen, carbon monoxide, an inert gas, hydrocarbon or equivalent

  in small amounts (0.1 to 5% of the oxidizing gas).

  An advantageous application of the process according to the invention

  consists in producing in an iron bath reactor a gas containing

  as little as possible of sulfur for burning in boilers and heating installations, for example for the production of electricity, from fuels containing sulfur. The sulfur is then absorbed by a slag containing CaO in an iron bath reactor. The necessary slag formers containing CaO are preferably added in a spray form to oxygen-containing gases which are injected into the iron bath below its surface. The mixture of slag formers with fuels, or a separate introduction of CaO with a carrier gas, also falls within the scope of

  the invention. The slag formed, including the ashes thus en-

  It can be fractionally evacuated during the reactor or, according to the German patent 25 20 584 for the improvement of the thermal balance, it can be desulfurized in the liquid state and be recycled always in the state.

liquid in the reactor.

  The application of the process according to the invention has for example made it possible, depending on the fuel used, exploitable gases having the composition given below. For the gasification of one ton of coke with about 10% of ash and a sulfur content of 1%, it is possible to arrive below the surface of the iron bath about 2,400 m3 of air preheated to a temperature of 3000C and simultaneously 2.400 m3 of preheated air is projected on the bath at the same temperature. The molten iron bath has a temperature of about 1.4000C and a carbon content of about 2%. Per ton of coke, 5,500 m3 of gas consisting of about 25% CO, 6% Co2, 69% N2, 0.002% sulfur was produced at a temperature of 1.4000C, said gas containing about 2 g / m3 of dust and can be directly burned in a boiler. During the gasification of a gas-producing coal, a gas having the following composition was obtained: 19.0% CO,

4.8% H2, 4.6% Co2 and 66.5% N2.

  A low energy and dried lignite corresponding in composition to 64.0% by weight of C, 4.9% by weight of H, 23.6% by weight of 0.5.9% by weight of ash, 0.4 % by weight of sulfur and having a calorific value of 5. 860 Kcalories was gasified with air at 3000C by the process according to the invention in an iron bath reactor and a gas containing 21.4% was obtained flight. of CO, 6.2% vol. H 2, 5.4% vol. of CO2, 6.2% vol. H20, 60.7% vol. N2, 20 ppm. of sulfur and having a calorific value of 806 Kcal./m3. For desulfurization, we introduced into the

  reactor about 9 Kg CaO / t. of coal.

  The use of oxygen in accordance with the invention is then always advantageous when the requirement to obtain a high energy gas with low N2 content comes back.

  plan or when particular fuels

  low in energy for gasification in the reac-

  iron bath. In order to define the oxygen carrier gases to be used, or whether to use pure oxygen during the gasification in the iron bath reactor, it is mainly based on considerations of profitability and also on the application produced gases. It does not arise

  problem concerning the operational techniques in the gasification

  During the balancing of the thermal balance of the process by the partial combustion of the gases produced in the reactor gas chamber and when using different agents containing

  oxygen in accordance with the process of the invention.

  Another particularly advantageous application of the invention consists in introducing into the bath in the reactor materials which contain iron in a fixed or free form, such as for example ore, for producing liquid iron (cast iron) and simultaneously for produce a gas. Under these conditions of application of the process according to the invention, the heat generated by the partial post-combustion of the gases produced in the iron bath reactor is used at least partially for

  reduction of iron-containing materials, including ore.

  The molten iron bath in the reactor is added in addition to solid or liquid carbon-containing fuels.

  as well as oxygen and slag

  which contain iron in at least partial form

  oxidized, such as ore. The essential economic advantage of this variant of the process according to the invention is that, with a low technical expense, ore is reduced directly using a relatively small amount of coal and simultaneously a gas is formed which can be used in many applications. For the production of one ton of iron by reduction of iron ore, it is necessary to use about 1.1 t. of coal (approximate composition 78% C, 5% H2, 3) H2Oi 5% ash, 5% 02 '1% S, calorific value 7,500 Kcal./ m3). Simultaneously, an industrially usable gas is produced having the following approximate composition: 57% CO, 14% CO 2, 14% H 2 O, and a calorific value of about 2,100 Kcal / m3.

  The method according to the invention thus makes it possible to optimize

  profitable production of iron in combination with the

  gas production in an iron bath reactor.

  If, for example, the energy produced by the post-combustion of the gases produced in the iron bath is operated in a similar way without the recovery according to the invention, it would be necessary to involve, when using the same coal for the manufacture of a ton of iron, about 3 t. of coal. The gas produced would have the following composition: 70% CO, 1% CO2, 27% H2, 1% H2O and a calorific value of approximately 2,700

Kcal./m.

  The other known multi-phase processes for the reduction of iron ore and for the production of liquid iron, for example according to the published patent application 24 01 909, have the disadvantage that the gases produced can not be used. in secondary applications, because of their low calorific value, if they do not add energy-rich gases, which is expensive. With this manufacturing process, it takes about 650 Kg of coal to produce one tonne of steel. A gas having the following composition is then produced: 41% CO, 30% CO 2, 18% H2O, 10% H2 and a calorific value of 1,100 Kcal./m. With the process according to the invention, the ore can be introduced into the iron bath both directly through nozzles placed in the bottom of the reactor than from the top on the surface of the

  bath. In accordance with an advantageous embodiment of the invention,

  The addition of ore takes place at least partially at the same time as the oxygen which is blown onto the bath. With this procedure, the ore in pulverulent form is already preheated

  and pre-reduced in the gaseous atmosphere, which increases the efficiency

  thermal effect of the process. To further improve this effect, it may be advantageous to place in the blowing nozzles devices which contribute to widen the jet with the ore particles, for example by pulling the jet out of the nozzle by swirling. As additives, which contain iron in

  part in an oxidized form, it is possible to use, in addition to

  different qualities, in particular dumplings and

  ore briquettes incompletely reduced.

  The process according to the invention can be used in a particularly advantageous manner in applications which make it possible to use the gases produced in the immediate vicinity as combustible gases, for example to replace natural gas. The

  gas produced by the process according to the invention and which has undergone parti-

  postcombustion practically has, because of the relatively high CO content, about the same temperature as natural gas and can thus replace this gas without having to

  make big changes to the devices of the ovens.

  The following example concerns the application of the process

  according to the invention to a reactor vessel, analogous to a conver-

  weaver, containing an iron bath of 60 t. In the heart of

  10 nozzles having a cross-section of 28 mm are provided. By means of two of said nozzles, coal dust is blown at a flow rate of 350 Kg / mm, in which case it is possible to use nitrogen, carbon dioxide or also reducing gas from converter. Through three nozzles, oxygen is injected at the same time as the ore and, through the other five nozzles, oxygen is injected, partly mixed with known slag formers for example lime. Through a side nozzle, which is located in the conical top of the converter, about 50% of the oxygen is sprayed onto the bath. With a coal having the

  composition and a mineral containing 85% Fe 2 O 3,

  than 20 t. of iron per hour, this iron having a carbon content of 3%. The oxygen consumption for the gasification of one ton of coal, with simultaneous melting of 1,450 kg of ore, amounts to

  580 m. A combustible gas having the precise composition is produced

  (about 57% CO, 14% CO 2, 14% H., 14% H2O) and a calorific value of 2.100 Kcal./m

  It is also part of the invention of

  the reactor vessel so that it simultaneously serves as a converter for the direct manufacture of steel. For this purpose, before each casting is carried out a reduction in the carbon content of about 2 to 3%, which is the normal value for operation in an iron bath reactor, up to about 0.05% and sinking an amount of about 20 t. There remains in the converter an amount of about 50 t. whose carbon content is slowly increased to 2 to 3% by simultaneous insufflation of oxygen and charcoal, with a slight excess of charcoal,

  carbon corresponding to the desired value in steady state.

  With this procedure, it has been found advantageous to remove the slag from the iron bath before completely removing the carbon by refining, i.e.

  residual carbon-between 0.5 and 2%. The new slag

  formed during ripening and which is in equilibrium with the

  withdrawn steel bath then remains in the converter.

  The process according to the invention will be described below with the aid of an application example and with reference to the appended drawing which is a longitudinal section of an iron bath reactor. A pear-shaped, gas-tight reactor vessel 20 is filled to about half of a liquid iron bath 21 so that the bath surface 22 is located approximately in the middle of the bath. In the bottom of the reactor, a nozzle 23 is provided for the introduction of finely divided coal 24. In addition, an oxygen nozzle 25 is provided in the bottom of the reactor vessel 20. intermediate of which oxygen is introduced, separately from the nozzle 23, in the liquid iron bath 21. In practice, this oxygen nozzle is surrounded, for protection, by an interval

  annular flow of hydrocarbons or similar materials.

  In the upper zone of the converter, it is

  two nozzles 26 and 27 which pass through the wall of the reactor vessel.

  They are supplied with air 28 and form the jets 29 which are

  directed approximately to the central area of the bath surface 22.

  The outlet ports of the nozzles 26 and 27 are placed at about 2

  m. above the bath surface 22.

  The gas jets 29 pass through the chamber 30 located

  above the bath surface 22 and carry with them a portion of the gas 31 already produced by the gasification of the coal 24. Under the effect of the oxygen contained in the jets 29, a portion of these gases 31 is burned. The heat of combustion is transmitted to the bath

  iron 21 through its surface 22.

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Claims (13)

  1. Process for producing gas in a bath reactor   where there is a bath of liquid iron which receives   liquids or solids containing carbon and on the surface of which is projected a jet of gas consisting at least in part   of oxygen, the fuels being gasified in the form of gas.   accumulate in the chamber placed above the surface of the bath and which are removed from this chamber, characterized in that the jet of gas is projected through said chamber on the surface of the bath and sucks during the passing through the chamber the gases produced by ensuring their partial burning and their entrainment to the surface of the bath so that the heat produced by the combustion of said gases is transmitted to the iron bath. 2. Method according to claim 1, characterized in that the jet of gas directed on the surface of the bath is composed of technically pure oxygen.   3. Method according to claim 1, characterized in that the jet of gas blown through the chamber and on the   Bath surface is formed by air.   4. Method according to any one of claims 1 to   3, characterized in that in addition to the jet of gas blown through the chamber on the surface of the bath, is introduced into the iron bath, below its surface, a gas consisting of less of oxygen.   5. Method according to claim 4, characterized in that the amount of oxygen sprayed on the bath surface is at least equal to 10% of the total amount of oxygen introduced. in the iron bath reactor.   6. Process according to any one of claims 1 to   , characterized in that the jet of gas thrown through   the chamber on the surface of the bath is preheated.   7. Method according to any one of claims 1 to   6, characterized in that the gas injected below the bath surface is preheated.   8. Process according to any one of claims 1 to   7, characterized in that the fuel is introduced into   the iron bath below the surface of the bath.   9. Process according to any one of claims 1 to   8, characterized in that the length of the jet of gas in the   room is greater than 2 meters. -11-   10. Process according to any one of claims 1   at 9, characterized in that gas and liquid iron are produced in the iron bath reactor simultaneously from materials which contain iron in at least partially oxidized form.   11. Method according to any one of claims 1   at 10, characterized by introducing into the iron bath,   as iron containing materials in at least partial form   oxidation, including ore, partially   reduced, like pellets and / or briquettes.   12. Method according to any one of claims 1   at 11, characterized in that the materials which contain iron in at least partially oxidized form, in particular   ore, are projected at the same time as the oxidizing gas, mainly   oxygen, on the bath.   13. Method according to any one of claims 1   at 12, characterized in that, in the reactor vessel, the   Iron product containing carbon is refined in the form of steel.