GB2095282A

GB2095282A - A method and device for producing a gas containing essentially H2 and CO

Info

Publication number: GB2095282A
Application number: GB8208340A
Authority: GB
Original assignee: Kloeckner Humboldt Deutz AG
Current assignee: Kloeckner Humboldt Deutz AG
Priority date: 1981-03-21
Filing date: 1982-03-22
Publication date: 1982-09-29
Also published as: DE3111168A1; ZA821860B; JPS57167390A; PL235514A1; DE3111168C2; AU8167782A; BR8201519A; AU551124B2; GB2095282B

Abstract

A method of producing a gas containing essentially H2 and CO by reaction of fuels containing carbon and/or hydrocarbon with oxygen and/or gaseous gasification media containing oxygen, while in contact with molten iron, the gasification means being blown in a stream of gas from above into the molten iron while fuel is introduced into the molten iron from beneath the surface thereof. The invention also includes apparatus suitable for carrying out the method. <IMAGE>

Description

SPECIFICATION A method and device for producing a gas containing essentially H2 and CO The invention relates to a method and a device for producing a gas essentially comprising H2 and CO by making fuels containing carbon and hydrocarbon, such as solid fuels, react with oxygen and/or gaseous gasification media containing oxygen, if necessary adding sulphurbonding substances, in contact with molten or liquid iron.

A method of gasifying coal by causing it to react with a stoichiometrically dimensioned quantity of oxygen in the molten iron have been known for some time.

For example, German Patent Specification No.

413680 describes a method of producing hydrogen and carbon monoxide in which fuel is introduced into a bath of molten iron below its surface so that carbon dissolved in the molten iron is able to react with oxygen and a slag is formed from the impurities and ash components. In this method fuel is lowered below the surface of molten iron from above in solid form as a block of solid fuel while the oxygen is introduced into the molten iron in a pipe made of fire resistant material which dips into the molten iron.

Another method in which fine grain or dust-like fuels and air are blasted through a molten liquid filter comprising high temperature molten substances, such as metals, is described in German Patent Specification No. 450 460.

The known methods have not however in the past been practicable because of difficulties in terms of the method and/or design. For example a suitable material for the pipe for introducing oxygen below the surface of the molten iron was not found since such a material has to withstand fairly long operation without damage. This relates to the situation where there are high local temperatures arising at the outlet point in the contact and reaction region between the oxygen and the iron due to spontaneous reaction of oxygen with carbon dissolved in the iron, in which any material is destroyed.In the case of the method according to German Patent Specification No. 413680 there was the further difficulty that the supply of coal in block form caused very slow emission of carbon to the molten iron and this necessarily resulted in a low carbon concentration in the molten iron and therefore impermissibly high proportions of carbon dioxide and sulphur dioxide in the product gas.

By using air as the gasification means in the method according to German Patent Specification No. 450460, the local temperature increase was kept within limits, since, when using water vapour to keep down the temperature when producing mixed gas, the necessity of introducing reaction media below the surface of the molten liquid gave rise to design problems and excessive cost with all the difficulties that this involves. Therefore in this specification, in contrast to the technical theory claimed, it was proposed that it was sufficient to blast fuel and air on to the surface of the molten filter, but without any indication as to how this should take place.In fact it is known that when the reactants are blasted on to the molten iron the degree of efficiency of the reaction is very much worse than when they are introduced below the surface; and that as a result undesirable gas components such as sulphur dioxide and/or carbon dioxide and carbon black and unreacting fuel components, such as carbon, are present in the product gas which is why it was not viable as a reduction gas or a starting product for petrochemical processes because of its poor quality.

In order to eliminate these difficulties, German Auslegeschrift No. 2520883 proposed a method of continuously gasifying coal or carboncontaining substances in a molten iron reactor in which the reaction partners, preferably fine grain coal and oxygen, are introduced into the molten iron in order to maintain continuous operation over a long period of time, through one or more nozzles which are arranged in the molten iron reactor below the surface of the liquid in the fire proof cladding and therefore these nozzles wear at the same rate and are surrounded by gaseous and/or liquid hydro carbons or hydro carboncontaining media in order to protect them from wear by oxygen and/or the media which contain oxygen.In practice, propane has proved to be suitable as a cooling agent for an oxygen nozzle, such as that in a steel converter which provides a blast at the base and is known from this technology.

When manufacturing a product gas by means of coal gasification in a bath of iron the dependence of the method on the use of these high quality cooling agents such as propane is regarded as a certain disadvantage.

The invention seeks to eliminate the difficulties and disadvantages described. In particular it is desired to avoid using high quality hydro carbon products as the cooling media and to reduce the design cost of a device required for this purpose.

According to a first aspect of the invention, there is provided a method of producing a gas containing essentially H2 and CO by reaction of fuels containing carbon and/or hydro carbon with oxygen and/or gaseous gasification media containing oxygen, while in contact with molten iron, wherein a gasification medium is blown in a stream of gas from above on to the molten iron and fuel is introduced into the molten iron underneath the surface of the molten iron.

Sulphur-bonding substances may be added.

The difficulties avoided by the invention in an advantageous manner are the necessity of blasting oxygen into the molten iron through an immersed pipe or a nozzle in the base. Therefore a coolant for the nozzle which contains hydrocarbon can be dispensed with and if necessary the tiltable, rotatable and/or pivotable arrangement out the reactor can be dispensed with. When blasting the gasification medium in accordance with the invention from above in a stream of gas on to the molten iron, it was shown surprisingly, that almost all of the oxygen took part in the reaction and reacted with the carbon dissolved in the iron particularly if, by introducing fuel from below the molten iron, the molten iron is kept continuously at high carbon concentrations of the order of magnitude of between 3 and 4.5%.This is because introducing fuel below the surface of the molten iron provides an adequate residence time for complete decomposition and solution of its carbon concentration in the molten iron, particularly if the solid added is in the fine grain range. In addition, the optimum kinetic conditions may be maintained in an advantageous manner and preferably intensive movement of the molten iron may be maintained in the molten iron at flow speeds of between 1 and 5 m/sec, preferably at approximately 2 m/sec.

It is proposed that the gasification medium should be blasted, preferably vertically, in at least one stream of gas and at such a force, that the stream of gas penetrates at least partially into the molten iron and it is further provided that the stream of gas may be accelerated by an acceleration nozzle to a speed of 2 to 5 Mach, preferably approximately 2.5 Mach and blasted over a distance of 5 to 60 cm, preferably 40 to 50 cm into the molten iron.

Surprisingly, it has become evident that a sharply focused high energy and continuous stream of gas at high speed over a relatively short distance and below the surface of the liquid is able to penetrate at least partially into the molten iron by means of a kind of injection effect without there being any excessive splashing.

Further it may be provided that the sulphurbonding substances be introduced beneath the surface of the liquid into the liquid and that fuel and/or sulphur-bonding substances such as Ca and Mg compounds be introduced into the molten iron with the aid of gas in the form of a slag forming agent.

Gases may be used for this in an advantageous manner and preferably do not contain any or very little oxygen, such as nitrogen, CO2, water vapour, cooled product gas, waste gas from a blast furnace etc.

The use of these gases is advantageous economically speaking particularly if low cost products are used, as in the case of waste gas from a blast furnace for example product gas.

It may also be provided that, in order to correct the stoichiometric ratios, a quantity of the fuel may if necessary be fed from above on to the molten iron.

An improvement in this method may be achieved by blasting gas underneath the surface of the liquid in order to produce movement of the liquid.

In fact it has become evident that intensive convective movement of the liquid is advantageous in maintaining a satisfactory gradient of concentration to optimise the kinetics of the reaction, in order to produce a quantity and quality of product gas from sulphur-containing fuels by the method in accordance with the invention.

The gas used to move the liquid may preferably have the same or a similar composition to the gas used to introduce fuel or sulphur-bonding substances into the molten iron. As a result it is possible to make use of the measure whereby fuels and/or sulphur-bonding substances are introduced into the molten iron and the movement of the liquid is generated by one and the same flow of gas.

In this case, for example, the quantity ratio between gas and solid may be set so that the operation provides an excess of gas and the gas serves both to transport the solids and to produce movement of the liquid.

According to a second aspect of the invention, there is provided apparatus for producing a gas containing essential CO by reaction of fuels containing carbon and/or hydrocarbon with oxygen and/or gaseous gasification media containing oxygen while in contact with molten iron, wherein the apparatus comprises a reactor for the iron, means for blowing a stream of the gasification medium from above the reactor and means for introducing fuel into the reactor below the intended level of the molten iron.

Preferably the reactor has a connection for a product gas pipe and a closable opening in the gas chamber of the reactor vessel for filling with molten iron, an outlet opening for siag at least one lance for connection to a supply of gasification means, arranged in the gas chamber and having an acceleration nozzle at a spacing from the surface of the molten iron, and at least one nozzle for introducing fuel below the surface of the molten iron.

Channels, inclined with respect to the base region may be provided in the side wall of the reactor, the openings of the channels lying in the reactor below the surface of the liquid and the inlet openings of the channels being arranged outside the reactor above the surface of the liquid and the channels themselves being connected to a gas supply line.

These channels essentially serve to introduce gas for the purpose of moving the liquid. The inclined arrangement in which the opening provided for outlet of gas into the liquid is below the surface of the liquid and the inlet opening is outside the reactor and above the surface of the liquid, prevents molten iron from running out in the case where the supply of gas is faulty.

Appropriate means, for example further nozzles or channels, may be provided in the base region of the reactor for introducing a gas for movement of the liquid and if necessary for introducing a sulphur-bonding substance. In the case where the manufacture of product gas takes place under pressure, the reactor is suitably equipped and in particular is made gas and liquid tight.

The invention will now be described in greater detail, by way of example, with reference to the drawings, in which: Fig. 1 shows a reactor carrying out one embodiment of the method in accordance with the invention, the reactor having a cylindrical crosssectional shape, in section, and Fig. 2 shows a similar reactor with an elongate basic shape, also in section.

According to Fig. 1 the reactor 1 comprises a steel sleeve 2 with a heat resistant lining 3. It includes a lower chamber 5 accommodating the molten iron 4, and having an approximately cylindrical shape and an upper chamber 6, the socalled gas chamber. Channels 8, 8' are arranged in the side wall 7, 7' of the lower chamber 5, which channels open inside the reactor 1 below the surface 9 of the liquid while they end outside the reactor above the surface 9 of the liquid and are there equipped with means for connection of a gas supply, for example with flanges. A channel 10 which is provided with a closure element 11 on the outside of the reactor 1 extends out from the base of the lower chamber 5 and serves to let out molten iron 4 from the reactor 1, if necessary.

Nozzles 13, 13' are arranged in the base region 12 and are provided for introducing fuel and/or sulphur-bonding additional substances with the aid of gas. In addition the gas may be used to produce movement of the liquid, caused by a flow of gas passing out of the nozzle 13, as indicated by arrow 14. The arrows 15,15' refer to the introduction of any desired substance with the aid of gas or the introduction of gas on its own.

Therefore fine grain coal together with product gas can be introduced into the molten iron 4 through the nozzle 13' arranged centrally in the base region 12, whereas the nozzles 1 3 at the base or a channel 8, 8' is used to blast gas in, for the purpose of producing movement of the liquid in accordance with the arrows 1 4. If desired, gas can be blasted in, in order to produce movement of the liquid or if necessary a solid can be blasted in with the gas through the inclined channels 8, 8' arranged in the side walls 7, 7'. In the upper chamber 6 above the surface 9 of the liquid a lowermost slag layer 1 6 can be seen floating on top of the surface 9, and a slag outlet opening 1 7 is at the level of the surface of the liquid.The outlet opening 17 is also closable, like the channel 10 by means of a closure element not shown. A blast lance 18 which has an acceleration nozzle 1 9 in the region of its opening projects into the upper chamber 6, the gas chamber of reactor 1.

The blast lance 1 8 is cooled and is provided with a cooling medium through a connection 20 as indicated by arrow 21. It is connected to an oxygen supply line not shown via a flexible hose 22 and is supplied with oxygen as indicated by arrow 23. An adjustable mechanism 24 serves to adjust the height of the blast lance 1 8. The reactor 1 is provided with a detachable lid 25 in the upper chamber 6, of the gas chamber, the guide 26 for the blast lance 1 8 being arranged centrally in the lid 25, and there is a closable opening 27 on the left hand side for filling with molten iron and also a connection 28 for outlet of the product gas, which is indicated by arrow 29.

Fig. 2 shows a reactor which only differs from the reactor according to Fig. 1 in that it has an elongate inner chamber. At its base region 12 three blast nozzles 13, 13', 13" are arranged and serve either optionally or at the same time to introduce carbon and/or sulphur-bonding additional materials and gas. Movement of the liquid instigated by blasting in gas through an inclined channel 8' is indicated by the arrow 14 in the molten iron 4. In addition the same operating elements are provided with the same reference symbols.There is a further difference as compared to the reactor according to Fig. 1 in that the opening 27 for filling with molten iron is arranged approximately at the centre of the gas chamber 6 and accommodates the guide 26 for the blast lance 18 which also has a cooling device 21 and an acceleration nozzle 1 9 at its opening.

The method according to the invention, which takes place in the reactors shown by way of example in Figs. 1 and 2, proceeds as follows: The reactor 1 is first of all filied with the required quantity of molten iron, the so-called iron bath 4, and the fill opening 27 is then closed. In addition there are nozzles 13, 13', 13" arranged in the base region 1 2 or channels 8, 8' opening into the molten iron 4 under gas pressure in order that iron cannot enter the nozzle or channels. The reactor is in connection with a product gas pipe via the connection 28. As soon as the molten iron is poured in, fuel, e.g. fine grain coal, in a grain size range of less than 100 microns for example, is blasted through a nozzle 13, 13', 13" arranged in the base region 12 with the aid of a carrier gas.In preferred manner, cooled product gas may be used as a carrier gas or some other gas which is low in oxygen. If, as the plant starts up, there is still no product gas available some other gas may also be used such as CO, CO2, nitrogen or flue gas.

At the same time that fuel is introduced into the molten iron 4, oxygen 23 is blasted by the lance 18 towards the molten iron 4 in a stream of gas from above.

In the start up phase of the method in accordance with the invention a certain amount of carbon is dissolved in the molten iron as fuel is introduced and the carbon content is increased continuously until there are carbon concentrations of between 3 and 4.5%. Together with the fuel a sulphur-bonding substance, if necessary mixed with the fuel is introduced into the molten iron as a slag forming agent, for example in the form of a calcium and/or magnesium compound and forms a layer of slag floating on the surface of the molten iron. The sulphur component of the fuel introduced into the molten iron 4, for example between 1 and 2% in a conventional coal is dissolved in the molten iron as the carbon carrier is dissociated, the molten iron passing the sulphur content to the sulphur bonding slag layer, since the molten iron only has a small absorption capacity for sulphur.

The stream of oxygen blasted at high force towards the molten iron 4 through the slag layer causes a blast impression on the surface of the molten iron, this impression forming a highly localized movement of the liquid in the iron melt, said movement having toroidal layer flow formation which causes an exchange between the surface layers of the molten iron 4 and the deeper layers.

A focus is formed in the blast impression of the stream of oxygen which is brought about by spontaneous and violent reaction of oxygen with carbon dissolved in the molten iron 4 and the oxygen reacts to a large extent with carbon to form H2 and CO-containing product gas. When the stream of oxygen is accelerated appropriately by the acceleration nozzle 19, for example at speeds of at least 2.5 Mach over a relatively short distance to the surface of the molten iron, a part of the high energy and concentrated stream of oxygen is able to penetrate into the molten iron. In addition a certain amount of splashing may occur and droplets of iron having a relatively large surface form further reaction areas for reaction with oxygen.During the course of the process of gasifying coal, the quantity of oxygen in the blast is set in a stoichiometric ratio with respect to the quantity of carbon introduced with the fuel into the liquid so that carbon concentrations in the molten iron are maintained around a mean value of between 3 and 4.5%. The great advantage of this is the enforced movement of the liquid which is achieved by blasting convection gas into the molten iron from below in addition to the introduction of fuel and/or sulphur-bonding substance so that the molten iron boils.

With the method in accordance with the invention, the carbon carrier and the sulphurbonding media and a quantity of gas sufficient to enforce movement of the liquid is introduced into the molten iron 4 from below by one and the same flow of gas for example through a preferably eccentric nozzle 13 on the base. Alternatively the carbon carrier and the sulphur-bonding substance and gas required to move the liquid may be introduced into the molten iron through different nozzles. The method is therefore flexible in this respect.

A sulphur balance is produced in the slag, by taking sulphur into the sulphur-bonding slag layer and continuously supplying fresh sulphur-bonding substances and this balance has to be maintained at such a level that sulphur is prevented from breaking through into the product gas. This is why slag enriched with sulphur is drawn off either continuously or periodically and replaced by a supply of fresh sulphur bonding substances.

Suitable operating parameters can be set by selective tests which depend on the substances used and this can be carried out without difficulty so that the process is continuous.

Control can be carried out appropriately by means of an easily determined magnitude.

Continuous analysis of the quality of the product gas would be a suitable example of such a magnitude.

Claims

1. A method of producing a gas containing essentially H2 and CO by reaction of fuels containing carbon and/or hydro carbon with oxygen and/or gaseous gasification media containing oxygen, while in contact with molten iron, wherein a gasification medium is blown in a stream of gas from above on to the molten iron and fuel is introduced into the molten iron underneath the surface of the molten iron.

2. A method according to claim 1 wherein sulphur-bonding substances are added.

3. A method according to claim 1 or 2 wherein the molten iron is made to move intensively and gas is blown in underneath the surface of the molten iron in order to produce movement thereof.

4. A method according to claim 3, wherein the molten iron is moved at flow speeds of between 1 and 5 m/sec.

5. A method according to claim 3, wherein the flow speed is at least 2 m/sec.

6. A method according to any one of claims 1 to 3, wherein the gasification medium is blasted in at least one stream of gas and with such a force that the stream of gas penetrates at least partially into the molten iron.

7. A method according to claim 6, wherein the gasification media is blasted vertically into the molten iron.

8. A method according to any one of claims 1 to 7, wherein the stream of gas is blasted through an acceleration nozzle at a speed of 2 to 5 Mach, over a distance of 5 to 60 cm, on to the molten iron.

9. A method according to claim 8 wherein the gas is blasted at a speed of approximately 2.5 Mach over a distance of 40 to 50 cm.

1 0. A method according to any one of claims 1 to 9, wherein the fuel and/or sulphur-bonding substances are introduced into the molten iron with the aid of gas in the form of a slag forming agent.

11. A method according to claim 10, wherein Co- and/or Mg-compounds are used as sulphur bonding substances.

12. A method according to claim 10 or 11, wherein gas which contains as little oxygen as possible or no oxygen is used.

13. A method according to claim 12, wherein the gas comprises nitrogen, CO2, water vapour cooled product gas or waste gas from a blast furnace.

14. A method according to any one of claims 8 to 13 wherein fuel and/or sulphur-bonding substances are introduced into the molten iron and the movement of the liquid is generated by one and the same flow of gas.

1 5. A method according to any one of claims 1 to 14 wherein part of the fuel is fed from above on to the molten iron.

1 6. Apparatus for producing a gas containing essential CO by reaction of fuels containing carbon and/or hydrocarbon with oxygen and/or gaseous gasification media containing oxygen while in contact with molten iron, wherein the apparatus comprises a reactor for the iron, means for blowing a stream of the gasification medium from above into the reactor and means for introducing fuel into the reactor below the intended level of the molten iron.

1 7. Apparatus according to claim 16, wherein the reactor has a connection for a product gas pipe and a closable opening in the gas chamber of the reactor vessel for filling with molten iron an outlet opening for slag, at least one lance for connection to a supply of gasification means, arranged in the gas chamber and having an acceleration nozzle at a spacing from the surface of the molten iron, and at least one nozzle for introducing fuel below the surface of the molten iron.

18. Apparatus according to claim 17, wherein the reactor has a further outlet opening for outlet of iron.

19. Apparatus according to claim 17 or 18 wherein the nozzle for introducing fuel is also connected to introduce gas.

20. Apparatus according to claim 17, 1 8 or 1 9, wherein the nozzle for introducing fuel is arranged in the base region of the reactor.

21. Apparatus according to any one of claims 17 to 20, wherein inclined channels which are inclined to the base region of the reactor are provided in the side walls of the reactor and the openings thereof are located in the reactor underneath the surface of the molten iron and their inlet openings lie outside the reactor above the surface of the molten iron and the channels themselves are connected to a gas supply line; and introduction means are provided in the base region of the reactor for introducing gas for the purpose of moving the liquid.

22. Apparatus according to claim 21 wherein the introduction means are also arranged for the introduction of sulphur-bonding substances.

23. A method of producing a gas containing essentially H2 and CO by reaction of fuels substantially as described herein with reference to the drawings.

24. Apparatus for producing a gas containing essentially H2 and CO by reaction of fuels substantially as described herein with reference to the drawings.