DE2713864A1 - Prodn. of clean gas contg. hydrogen and carbon mon:oxide - by gasification of coal in metal melt - Google Patents

Abstract

Gasification of coal to produce a CO- and H-contg. gas which is free of sulphur and particulate impurities is carried out by injecting coal, O2 and a coolant (esp. water) into a metal melt. The coal is injected in a stoichiometric excess w.r.t. the oxygen present in the melt in the form of oxide cpds. The coal and O2 are pref. injected into the metal (pref. Fe or Cu) melt in a ratio such that H2O and CO2 formation are suppressed. The C/H molar ratio in the material injected into the melt is pref. 0.25-4, and the C/O ratio is pref. 1.2-4.6. The process is pref. stopped when the S content reaches a max. of 1000 ppm., after which the S is removed from the melt by blowing with O2 or adding CaO. The product gas canbe used asa fuel or processed to produce synthesis gas (esp. for methanol synthesis). Clean product gas can be produced from a wide range of coal types (including peat and wood products). Sulphur accumulating in the melt can be recovered in the form of an SO2-rich gas (e.g. useful for H2SO4 mfr.).

Description

Process for the production of a carbon dioxide gas and water

material gas for further refinement or incineration containing gas mixture The present invention relates to a method for producing a gas mixture, which contains carbon dioxide gas (CO) and hydrogen gas (H2) that are suitable for combustion or Further processing are provided.

It is a number of processes for the industrial production of carbon dioxide gas (CO) and hydrogen gas (H2) are known. It is known to produce coal by e.g. the Lurgi process, to gasify the hygas process and the bigas process to carbon dioxide gas. It is further known, hydrogen gas by e.g. electrolysis or fission at high temperature to manufacture.

In the production of hydrocarbon compounds, in general Assumed among other things from carbon oxide gas and hydrogen gas. For example, methanol (CH30H) becomes made from carbon dioxide gas and hydrogen gas.

The coal used is mostly contaminated, e.g. with relatively high sulfur contents. The coal gasification processes mentioned, at who burn large quantities of coal, therefore, give large quantities of sulfur dioxide (S02). The large amounts of sulfur dioxide generated in the processes (S02) are a big problem because the emission of sulfur dioxide is an unfavorable one Has an effect on the atmosphere, nature, the environment, etc.

Furthermore, the exhaust gases from coal gasification plants contain significant Amounts of dust consisting of, among other things, oxides of pollutants.

The present invention solves the aforementioned problems. In which Process according to the invention is hydrogen gas simultaneously with carbon oxide gas manufactured what the process for the production of hydrocarbon compounds, such as.

Methanol, makes it extremely attractive.

The present invention thus relates to a method of manufacture an essentially sulfur-free and dust-free gas mixture for further refinement or combustion, consisting essentially of carbon monoxide (CO) and hydrogen gas (H2) consists of carbon (C) in the form of coal, which contains a certain amount of water, Contains hydrocarbons and / or carbon compounds such as organic material. The invention is characterized in that said carbon is poured into a metal melt in a stoichiometric excess in relation to that contained in the molten metal Oxygen in the form of oxidic compounds, together with oxygen gas and together with a coolant.

The invention will be described hereinafter, in part with reference to FIG attached drawing, described in more detail. Fig. 1 in the drawing shows a device, in which the procedure according to

of the invention can be applied.

In Fig. 1 is schematically a gasification reactor with the general Designation 1 for the production of gas according to the invention shown. The on and for Gasification reactor known in principle contains a furnace body 2, preferably an electrical Frwärmungseinheit 3 and one or more blow holes 4 and one Collection hood 6 for generated gases. The walls of the Furnace body 2 are in a heat-resistant material, e.g.

Brick, and executed with an outer wall 10 made of metal.

The electric heating unit 3 is preferably an electric one Inductor. 11 denotes electrical line connection points. To the blowhole or the blow holes 4 are connected to one or more powder syringes 5 via lines 7.

A carrier gas, preferably oxygen gas, flows through each Proportioning means 8 belonging to the powder syringe 5 into the line 7. The proportioning means 8 is intended for the delivery of the reactants from the container of the powder syringe 5 to line 7 in a certain ratio to each other and in relation to the Amount of overflowing carrier gas to be injected into the device. The carrier gas can also consist of, for example, a mixture of carbon dioxide gas and carbon dioxide exist. Then, however, oxygen gas must be added in a different way.

Metal 9 is provided in the furnace body to keep it liquid.

If no reactants are injected into the gasification reactor, then the molten metal 9 kept warm by said heating unit 3.

The powder syringes 5 can have several containers for different reactants contain. Solid form reactants are added to the powder syringes in in powdered form.

The reactants are thus seen as a mixture of gas, solid powder grain and, if necessary, injected liquid.

The process according to the invention has the following course. carbon (C) in the form of commercial charcoal containing a certain amount of water, hydrocarbons and / or contains carbon compounds as well as oxygen gas, is together with injected a coolant into the molten metal 9. Here the carrier gas drives which preferably consists of said oxygen gas, residues of said reactants from said powder syringe 5 into the molten metal 9.

In the method according to the invention, a starting melt is assumed, either from a separate melting furnace or from the existing heating device 3 is melted and kept warm.

At the start of the injection, the reactor is tilted so that the blowhole or the blow holes 4 open above the surface of the melt. After the start of the Injection, the reactor is erected so that the blowhole or blowholes lie below the surface of the melt.

Injecting the reactants and coolant can also be done by one or more lances are made, which are submerged from above into the bath. Furthermore, in certain cases, the coolant can be applied to the molten metal from above will. In those cases when a lance is used, it is first put into the molten metal submerged after carrier gas and powder began to flow through the lance to lead.

In the case of the prevailing in a metal melt of the type provided here At temperature, carbon turns into carbon oxide gas very quickly and with high yield oxidized.

As mentioned, black coal contains a certain amount of water and certain amounts of hydrocarbon compounds.

Injected hydrocarbons, other carbon compounds and water are split in the molten metal, so that carbon, oxygen and hydrogen are released. Injected carbon and oxygen gas, as well as carbon and oxygen formed during cleavage, react to form carbon oxide gas after the exothermic reaction The released hydrogen is released in the form of hydrogen gas (H2).

The splitting of hydrocarbons and water are endothermic reactions. The exothermic oxidation of carbon, however, results in the formation of excess heat result, so that cooling of the molten metal is necessary. This is done through Introduction of the said coolant into the molten metal 9.

According to the invention, the coolant can be a hydrogen-containing compound, preferably water. When using water as a coolant, this split so that large amounts of hydrogen gas are formed, and at the same time the required amount of injected oxygen gas decreases.

The gases produced in this way, carbon oxide gas and hydrogen gas, are used in the Collection hood 6 collected and treated in the desired manner.

However, it is desirable for various reasons that the coolant Metal or metal oxides of the same metal from which the melt essentially consists consists. This is particularly advantageous in the event that the above-mentioned method is used the production of a metal is combined. The coolant contains in such Case preferably Schlich, which consists essentially of metal oxide.

Injected metal oxides are in the molten metal according to the formula MeO + C-> CO (g) + Me reduced, in which Me denotes the metal in question. The cooling is effected by the fact that the cleavage of the oxides is an endothermic reaction is.

As an example, it can be mentioned that when the molten metal is a Is iron melt, which consists essentially of Je203, Fe3O4 and FeO.

Metal oxides are in the molten metal to the above Way injected.

Slag builders, such as calcium oxide (CaO), are useful for Rinse of gangue added to the metal oxides introduced into the melt and coal ash introduced with injected carbon.

In the event that the molten metal consists of a metal that has a higher affinity for sulfur than for oxygen, metal scrap is preferred of the metal in question.

Examples of such metals are copper, lead and zinc.

Metal scrap is added to the melt either by means of called injection or fed down into the molten metal by placing it from above. In this latter In the case of cooling is essentially effected by the fact that the scrap metal becomes one Temperature above the melting temperature is obtained.

The reactions burning of coal, splitting of oxides, hydrocarbons and water, as well as the melting of metal scrap take place in the metal melt, which is a heat-absorbing or heat-emitting medium for the reactions. The molten metal is also a filter for dust particles, e.g. oxides, which are introduced with the reactants or formed during said reactions, as well as for emerging gases such as carbon dioxide (CO2) and sulfur dioxide (SO2). In particular, the molten metal is an absorbent for by-products, which are formed in reactions where components have a high affinity for the molten metal to have.

Thus, with the present invention, due to the dust absorption obtained in the molten metal a largely dust-free gas. Further the content of sulfur dioxide in the exhaust gas is very low, as sulfur is produced during combustion of coal and coal dissolving into the melt is absorbed by this. The metal in the molten metal can according to Invention partially after desired ability to absorb sulfur can be selected. The metals zinc, Copper, lead, iron and nickel have temperatures close to the melting point of the metal in question has an affinity falling in the order mentioned Sulfur.

It is therefore particularly advantageous to use the metals zinc or copper choose when the sulfur content in the injected coal is high to prevent formation of sulfur dioxide to suppress.

Another advantage is achieved when using metals such as zinc, copper, Lead, etc., which have a lower melting point than iron, because due to the lower melting point, the lining of the furnace body 2 a has a much longer lifespan than when using iron. Since renewing Since the lining is expensive and time-consuming, this is a costly issue economic and practical advantage. Furthermore, there is separation of sulfur from the Metal melt simply, and the sulfur can be considered a pure gas of sulfur dioxide for the production of e.g. sulfuric acid (H2S04) are obtained in a known manner.

Depending on the metal in the molten metal, the reactions take place between Carbon and oxygen contained in the injected reactants one of the following four ways or their combinations: a) Oxygen is in the Melt dissolved. The oxygen comes from injected oxygen gas, split one Water or other split oxides or hydrocarbons.

Carbon particles lying in the bath or on the gas / metal phase boundary are oxidized by dissolved oxygen in the metal, according to the formulas: This happens in cases when the metal redeems oxygen but not carbon, e.g. copper.

b) The reactants react directly with one another in the injection jet, according to the formula c) Carbon is redeemed in the melt. The carbon is oxidized at the gas / metal phase boundary or on oxide particles in the melt, according to the formula This happens in cases when the metal dissolves carbon but not, or only partially, oxygen, e.g.

Iron.

d) Carbon and oxygen are dissolved in the melt, where they react to form carbon oxide gas, according to the formulas This applies, for example, to an iron bath.

Oxygen in injected water and possibly injected hydrocarbons is split off and reacts with carbon like injected oxygen gas one of the specified modes a-d or combinations thereof. In the case of a split hydrogen is released.

At the temperature prevailing in a molten iron (e.g.

1400-1600 ° C) the equilibrium for the reaction 2CO-CO2 + C is strong shifted to the left. In a molten metal with a significantly lower temperature, like lead, a high level of CO is sustained by a lack of oxygen gas, since the equilibrium is then shifted less strongly to the left.

When using the method according to the invention, carbon, Oxygen, water and possibly hydrocarbons added in such proportions, that the exhaust gas has the most suitable composition with regard to its intended application obtained from carbon dioxide gas and hydrogen gas. The exhaust gas can e.g.

as fuel gas (CO), hydrogen gas (H2), for the production of hydrocarbons, like methanol (CH30H) or for the production of hydrogen-nitrogen compounds, such as ammonia (NH3) can be used.

The process mentioned is particularly suitable for the production of Methanol, as both carbon dioxide gas and hydrogen gas are generated. When synthesized of hydrogen gas and carbon dioxide gas to methanol is a hydrogen gas / carbon dioxide gas ratio of 2.1: 1 required. When burning coal with injection of only carbon and oxygen gas a ratio of 1: 4 is obtained ¢ By adding water as However, coolant can reduce the hydrogen content in the exhaust gas to a theoretical ratio can be increased by 1: 1. This ratio is to be regarded as a stoichiometric maximum. Injected water, however, cools the melt strongly, so that, without supplying external Heating energy by for example said heating device 3, a thermal maximum which is 1: 4.2 when only injecting carbon, water and oxygen gas will. In order to achieve this latter relationship, it can be mentioned as an example, that for the development of 10 Nm3 exhaust gas per minute and ton of melt in a melt with a weight of 30 tons 2.6 kmol H20 and 4.0 kmol oxygen gas together with 10.8 kmol of carbon are injected per minute. By injecting hydrocarbons with an average composition between CH2 and CH4, the ratio can be be increased, since their splitting together with subsequent oxidation of carbon represents a series of exothermic reactions.

In the method according to the invention, carbon becomes as in the above appears in a stoichiometric but shot in relation to in the molten metal containing oxygen in the form of oxidic compounds. The excessive Amount of carbon is oxidized by oxygen injected with the reactants. Further, said carbon and oxygen gas become mutual in such a way stoichiometric ratio that the formation of carbon dioxide (CO2) and injected Water (H2O) is suppressed.

The proportion between carbon (C) and hydrogen (H) that is injected is preferably such that the molar ratio between injected carbon and injected hydrogen is 0.25: 1 to 4: 1.

Further is the proportion between carbon (C) and oxygen (0), which are injected, preferably so that the molar ratio between injected Carbon and injected oxygen is 1.2: 1 to 4.6: 1.

To produce methanol from the gas mixture, a portion of the carbon oxide gas produced is preferably used to form hydrogen gas in a known manner according to the exothermic formula applied, after which the carbon oxide gas is scrubbed out of the gas mixture. The gas mixture and the amount of carbon dioxide gas for the production of hydrogen gas are adjusted so that the remaining gas has a hydrogen gas / carbon dioxide gas ratio of 2.1: 1, ie the stoichiometric ratio of these gases in methanol. The exhaust gas is passed on to a known synthesis process for methanol. An example of a synthesizing process is briefly given below.

The synthesis takes place in the following stages: a) The gas mixture of carbon oxide gas and hydrogen gas is through a cooling and dust cleaning unit directed. Although the gas mixture is essentially dust-free, it must be dust-cleaned as an absolutely dust-free gas mixture for the production of methanol necessary is.

b) The gas mixture is fed to a gas dome and collected there, to compensate for intermittent steps in the process.

c) The cooled, purified gas is compressed to 30 bar and reacted with steam in a so-called exchange reactor, where heat is exchanged between the incoming gas and the outgoing gas, with the exothermic reaction is carried out as described above to adjust the hydrogen gas / carbon oxide gas ratio to 2.1: 1.

d) carbon dioxide and possibly remaining sulfur compounds removed in an absorption system.

e) The gas is compressed to 100 bar, after which the synthesis to methanol takes place in a reactor where heat exchange between incoming and outgoing Gas takes place.

f) The outgoing gas is condensed to liquid methanol.

An alternative to using part of the carbon dioxide gas produced for conversion with water to hydrogen gas and carbon dioxide is separation of one part of the generated carbon dioxide gas in a known manner, so that the gas mixture is brought about becomes, the stoichiometric ratio of carbon dioxide gas and hydrogen gas in methanol to accept directly.

The generated gas mixture of carbon oxide gas and hydrogen gas can also be made to adjust the stoichiometric ratio in other Accept hydrocarbon compounds as methanol, e.g. ethanol, butanol, etc. This can be done either by reacting part of the carbon oxide gas produced with Water to hydrogen gas and carbon dioxide or by separating part of the generated Gas mixing happen.

A very big advantage of the method according to the invention is that that the injected carbon can be of very variable quality. It can e.g. lignite or anthracite as well as high-sulfur or low-sulfur types of coal injected. Furthermore, as I said, hydrocarbons of various types as well as other carbon compounds are injected. Coal in the form of vegetable Material, e.g.

Finely divided peat and wood products can also be injected will.

The metal in the molten metal has a high affinity for sulfur, so that this is redeemed in the molten metal.

Such amounts of reactants are preferably injected that the sulfur content in the molten metal is brought to a maximum of such a value that the sulfur dioxide content in the gas mixture is 1000 ppm, after which the molten metal is purified from sulfur. Depending on the metal chosen, its sulfur purification is carried out in different ways. If the affinity of the metal for oxygen is much lower than that of sulfur, which is the case for copper, for example, sulfur purification by oxidizing the sulfur in the known manner is popular. with the formula Cu2S + ° 2-- 2Cu + S02. However, if the affinity of the metal for oxygen is not sufficiently lower than that of sulfur, which is the case for iron, for example, desulfurization with a desulfurizing agent, such as calcium oxide CaO, is often used. the formula The sulfur purification is expediently carried out on an occasion where there is no injection, so that an effective collection of sulfur dioxide or CaS can take place.

In the event that a coolant is added, the metal or metal oxides contains, the volume of the molten metal increases.

Molten or reduced metal is thus produced as a by-product as well as slag obtained from coal ash and gangue, as mentioned. To The so-called sulfur purification and slag removal becomes part of the metal poured in a known manner so that the molten metal has a suitable volume gets back.

As described, the present invention offers great advantages compared to known processes for gasifying coal.

The most important advantages are that an essentially sulfur and dust-free gas can be generated from coal with high sulfur and dust contents can, and that sulfur introduced into the molten metal with the reactants should be removed from the melt in a relatively concentrated form and collected can. Collected sulfur in the form of sulfur dioxide can be used as a raw material for e.g. The production of sulfuric acid is used.

Another notable advantage is that essentially all of the in carbon contained in the reactants is oxidized to carbon oxide gas. Further be gladly. of the invention large amounts of hydrogen gas essentially by injection made of water, which also acts as a coolant for the exothermic oxidation of Serves carbon, or by injecting hydrocarbons.

The by-products from a process according to the present method consist of metallic material, which is the combination of coal gasification with metal production made possible, whereby the by-product also represents a large egg.

Another great benefit of the process is its ease of use Regulation in that the injected reactants are selected within wide limits to give desired gas compositions.

The invention is not limited to the examples described above limited by embodiments. The amounts of injected material vary Varieties can e.g.

varies significantly outside the values given in the examples will. A large proportion of the injected material can consist of hydrocarbons, for example exist.

Furthermore, molten metals other than those specified above can be used. A large number of gas compositions beyond those mentioned above can be produced according to the invention.

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Claims (13)

Claims 1. A method for producing an essentially sulfur-free and dust-free gas mixture for further processing or incineration, which essentially consist of carbon monoxide (CO) and hydrogen gas (H) from carbon (C) is in the form of coal, which contains a certain amount of water, hydrocarbons and / or contains carbon compounds such as organic material, d u r c h it is not noted that said coal is in a molten metal in one stoichiometric excess in relation to the oxygen contained in the molten metal in the form of oxidic compounds together with oxygen gas and together with is injected with a coolant. 2. The method according to claim 1, d a d u r c h g e k e n n -z e i c h n e t that said coal and said oxygen in such a mutual stoichiometric ratio that the formation of carbon dioxide (C02) and water (H20) is suppressed. 3. The method according to any one of claims 41 or 2, d a d u r c h g e it is not indicated that the said coolant is metal oxide and / or metal scrap of essentially the same metal as the main component in said Molten metal forms. 4. The method of claim 1, 2 or 3, d a d u r c h g e k e n n notifies that said organic material contains peat or wood products. 5. The method of claim 1, 1, 3 or 4, d a d u r c h g e k e n n e i c h n e t that carbon or carbon compounds containing sulfur, be injected into the molten metal in such an amount that the sulfur content in the molten metal is made to reach a maximum of such a value, that the sulfur dioxide content in the gas mixture is 10000 ppm, after which the molten metal on to and is purified from sulfur in a manner known per se. 6. The method according to any one of claims 1-5, d a d u r c h g e k e n it should be noted that Jjs is the molar ratio of carbon (C) to hydrogen (H), injected into the molten metal is 0.25: 1 to 4: 1. 7. The method according to any one of claims 1-6, d a d u r c h g e k e n It is noted that the molar ratio of carbon (C) to oxygen (0), the injected into the molten metal is 1.2: 1 to 4.6: 1. 8. The method according to claims 1-7, d a d u r c h g e -k e n n z e i c h e t that said coolant contains water. 9. The method according to any one of claims 1-8, d a d u r c h g e k e n It is noted that the main constituent metal in the molten metal is iron consists. 10. The method according to any one of claims 1-8, d a d u r c h g e k e It is noted that the main constituent metal in the molten metal is made up Copper is made. 11. The method according to any one of the preceding claims, d a d u r c h e k e k e n n n e i n e t that said Ko is oxygen gas and a hydrogen-containing gas Compound, like water, is injected in such mutual proportions that called gas mixture is brought to such contents of carbon oxvdgas and hydrogen gas to assume that by converting a certain amount of water and carbon dioxide gas produced to hydrogen gas and carbon dioxide the gas mixture is brought to the stoichiometric Ratio of carbon monoxide and hydrogen gas in a hydrocarbon compound, such as. To assume methanol, ethanol, butanol, etc., and that said gas mixture in a suitable, per se known manner to be named hydrocarbon compound is converted. 12. The method according to any one of claims 1-10, d a d u r c h g e k e It is noted that coal, oxygen gas and said hydrogen-containing compound be injected in such mutual proportions that said gas mixture is made to assume such contents of carbon dioxide gas and hydrogen gas, that by removing a certain amount of carbon dioxide gas from the gas mixture the Gas mixture is brought to the stoichiometric ratio for a hydrocarbon compound, such as methanol, ethanol, butanol, etc., and that said gas mixture in a suitable, per se known manner to be named hydrocarbon compound is converted. 13. The method according to claim 11 or 12, d a d u r c h g e k e n n it is noted that said hydrocarbon compound consists of methanol.