DE2443740A1 - METHOD OF CONVERTING COAL INTO A COMBUSTIBLE GAS - Google Patents

Description

PATENT ADVOCATES A. GRÜNECKER

DIPL.-INQ.

H. KINKELDEY

DR.-INQ.

2ΛΛ37ΑΠ W. STOCKMAIR

^ "DR-ΙΝβ. A ·? (CALTECH)

K. SCHUMANN

Often. RBR. N * T. · DIPL.-PHY3.

P. H. JAKOB

DIPL.-INQ.

8548 ^{G BEZOLD}

DR. RER. NAT. · DIPL.-CHEM.

33 / Sch. ' MUNICH

E. K. WEIL

DR. RCR. OEC. INTO THE.

LINDAU 8 MUNICH 22

MAXIMILIANSTRASSE 43

September 12th 1974-

USS EHGINEERS AUD CONSULTANTS, IHG.

600 Grant Street, Pittsburgh / Pennsylvania, USA

Process for converting coal into a combustible gas

The invention relates to a method for converting egg to a flammable gas.

Hydrogen is a gas that is used industrially for the production of various chemicals and for the reduction of iron ore. The main industrial process for the production of high purity hydrogen is that natural gas with the help of Steam is split. In most areas where natural gas is available cheaply, this process is the most economical. However, there are areas where natural gas is not available or where it is so costly, if it occurs,

- 2 -

509811/0892

that it is not suitable for use in hydrogen production, so other methods must be used.

A widely used process is the splitting of naphtha underlying. However, there are also areas in which haphta is not is available or in which it is not transported cheaply can be so that other starting materials must be used.

A process for producing hydrogen from one of natural gas or maphta consists of the partial starting material Oxidation of coal. In this process, coal is cut to a grain size corresponding to -60 mesh using conventional grinding equipment wed and then to. about 50% by weight mixed with water. The coal-water sludge becomes after a pressure of 84.4 · to 105.5 Atmospheres are pumped to a number of preheaters in which it is vaporized. The coal-steam mixture then becomes partial with preheated oxygen in a pressurized (28.1 to 35) 2 at) gasification vessel using specially designed burners burned. The ash content of the coal is drawn off with the aid of a water pump at the bottom of the gasification vessel. The resulting Mixed gas of hydrogen and carbon monoxide is converted to 98% hydrogen processed, which in two conversion steps and a carbon dioxide removal consists. The main disadvantage of this system is that it relies on the use of oxygen, because the capital requirement for an oxygen plant is very high. aside from that The cost of running the oxygen plant significantly affects the cost of producing hydrogen.

Before the present invention, it was known to use coal to dissolve in a molten metal bath to produce a combustible gas to win. One such method is U.S. Patent 3,533

509811/0892

can be seen after which a sulfur-containing carbon-containing fuel in Met all melts) ad is injected to primarily to extract gases containing carbon monoxide, while the sulfur-containing products are absorbed in a layer of lime will. According to a method known from US Pat. No. 3,264,096, coal is used as the reducing agent in the reduction chamber an ore smelting furnace.

The present invention relates to a method for producing hydrogen. In the context of the invention it is particularly provided that a mixed gas flow of hydrogen and carbon monoxide is generated by dissolving pulverized coal in a molten metal bath, whereupon the dissolved carbon is reacted with oxygen or steam or a mixture of these substances in order to generate a gas flow, which is rich in hydrogen and carbon monoxide. The gas stream can then be converted into high-purity hydrogen, which takes place with the aid of a versatility conversion of the carbon monoxide with steam, which is followed by a washing process in order to remove the carbon dioxide. Alternatively, the high-purity hydrogen can also use the author a r ens be released, which is published in of the following reference which was issued by the US Department of Interior: Institute of Gas Technology Office of Goal Research Report, Contract Ήο, 14- 01-0001-381, August 1966.

The invention is based on the object of creating a method which allows the production of high-purity hydrogen from coal in a cost-effective manner with high yield.

This object is achieved according to the invention in that a) the Coal pulverizes, b) the pulverized coal in a first zone of a molten iron bath containing 1-3% dissolved carbon is introduced, whereby the carbon concentration is 3-5%

50981 1/0892

it is increased that c) a second zone of the molten bath, which has a carbon concentration of at least 3 % ", is brought into contact with oxygen or steam as the oxidizing agent, and d) a mixture of hydrogen and carbon monoxide in a ratio of hydrogen to carbon monoxide from 2: 5 "to 10: 1 is picked up.

A particular advantage of the method according to the invention is to be seen in the fact that with the help of a water he st off production plant is achievable, which for a given reactor size provides a greater output than other plants that use coal as a starting material.

Another advantage of the invention is the fact that the Process according to the invention with regard to its operating costs quite comparable with other hydrogen production processes which use coal as a raw material. The invention also has the advantage that it is a uniform process proposes to produce hydrogen from coal by reacting it with steam.

Further features, advantages and details of the invention emerge from the following description of an exemplary embodiment based on the drawing. In this show:

1 shows a flow chart of the method according to the invention, at which steam or preheated oxygen as a reactant to generate the hydrogen-rich one Gas stream is used,

Fig.2 shows the embodiment of Fig.1, with a twofold Gas removal system is provided to avoid the need to add the total volume of gas formed treat.

50981 1/0892

_ 5 -

2U3740

As can be seen in FIG. 1, raw coal is extracted from a storage bunker 10 with the aid of suitable conveyors 12 or the like. transported to a grinding or grinding machine 14- in which the coal is pulverized and dried with warm air from an air heater 15. The pulverized coal is then fed via a line 16 to a number of cyclones 18 and fine sieves 20, in which the pulverized coal is sieved to a separation grain size of 30 mesh to be subjected to a further grinding process, while all other materials are collected in a bunker 24. From the bunker 24- the pulverized coal arrives at a pneumatic coal injection system, which consists of a suction bunker 26, a collecting injector 28 and a main injector JO, a compressor 32 and a suitable line 31 for conveying the coal to the end nozzle 38. The coal is injected from the lance 38 of the coal injection system into a gasification reactor 40 in which a molten bath 39 is formed a hot metal having a temperature of about 1538 ⁰ C is located. The reactor 4-0 is provided with a slag outlet 4-3. a lime-Eindüs system, which consists of a collecting bunker 4-2a, a collecting injector 4-2b and a main injector 4-2c, adds a small amount of lime to form a slag with the sulfur and ash content of the coal. If the coal injected and dissolved in the bath 39, so permitting the carbon content of the bath to increase from an initial value of 2% to 4%, while the bath temperature by this step 1538 ° C to about 14-82 ⁰ C is decreased. At this point in time, steam or oxygen is injected into the bath from a steam or oxygen injection lance 44, which is arranged on the wall of the gasification reactor 40 opposite the lance 38, in order to reduce the carbon content again by 2% and to release a gas containing hydrogen and carbon monoxide. the

509811/0892

molten solution and / or the carbon dissolved therein can circulate in the bath 39 or be distributed in the same, for which purpose Openings 33 are provided in a separator 35. The separator 35 maintains a clear separation between the carbon and the fresh the low carbon side of the bath 39 upright. Kick the gas out of reactor 40, it flows through a heat exchanger 50 to its heat for steam generation in a drum 41 or for other purposes.

When using steam as an oxidizing agent, it has a gas mixture at the outlet of the reactor 40 typically the following composition:

YOL .-%

H ₂ 56.8 % CO 41.2 co ₂ 0.4 N ₂ 0.3 H ₂ O 1.3

100.0%

This gas can be converted with the aid of conventional measures, such as a catalytic conversion with the aid of steam and with the help of monoethanolamine (MEA) at point 52 washed to remove carbon monoxide. The resulting Gas has the following composition:

Hg CO 00.

Ed

VOL.- % 98.40 % 0.42 0.27 0.33 0.50 100.00 % | R1 1 / nfi92

If oxygen is used as an oxidizing agent, after the catalytic shift conversion and purification with MEA at point 52, the following results are obtained at points A "and B were determined:

Gas test and part YOL .-% V0L .-% ^H 2 29.0 97.77 CO 69.7 0.70 co ₂ 0.7 0.45 IT ₂ 0.6 0.58 H ₂ O - 0.50

Total 100.0 100.00

Figure 2 shows a dual gas flow removal system, at which the gases developed in the two reactor sections are collected separately.

According to Pig. 2 is carbon monoxide from the oxygen injection section of the reactor by pipe 54 of the conventional verses hi ebungsumwanderung and the washing process with MEA fed at the point. The gases coming from the coal injection side emerge through line 56 and that of the treated gas stream originating hydrogen is combined with the untreated gas stream in a collecting container not shown. The gas flow components in stages A, B and G shown in FIG are as follows:

50981 1/0892

24Λ3740

Gas components V0L .-% V0L .-% V0L .-% H ₂ 87.55 - 94.45 CO 10.75 99.00 4.22 co ₂ - 1.00 .. 0.43 N ₂ 1.70 - 0.56 H ₂ Q - - 0.34

Total 100.00 100.00 100.00

Preferred volume ratios of hydrogen to carbon monoxide are in the range of 1: 1 Ms about 3: 1 «

Investigations into the rate of dissolution of carbon have been made taken and carried out to determine the effect of various amounts or rates of coal injection.

In the study of the dissolution rate, cylindrical graphite rods were used as carbonaceous materials and made from powdered Alpheus charcoal (-8 and 30 mesh). The rods with a diameter of 50.8 mm were made of high purity Electrode carbon. Electrolyte iron was used as the material for the weld pool.

A 150 KW voltage source with a frequency of 300 Hz was used to melt the iron in a 226.5 kg induction furnace lined with castable magnesite. In each pass, 226.5 kg of iron and 0.56 kg of silicon (as Eerrosilicon) were used at temperatures of 1593+. 30 ⁰ C melted. After the deslagging of the melt, the carbon additions and the time measurements were started. Metal samples were taken periodically to determine carbon. As a result of the inductive heating, a

50981 1/0892

intensive bath mixing.

At the. Graphite was another research carried out Single rod held vertically in the middle of the bath. If the stick had loosened sufficiently, it was immediately replaced by one another replaced. Charging was carried out in such a way that the grain size classified coal was on top the melt was scattered and the coal was continuously stirred into the metal, for which purpose stirring tools were used in this way improve the contact between the liquid and the solids. The enamel surface became during the furnace travel kept covered with the help of coal that has been added in the meantime. The slag is removed from the surface at suitable intervals removed, whereupon the surface was covered again with charcoal.

Three attempts were made at. which graphite rods and pulverized Alpheus charcoal were used. As soon as the coal was scattered on the hot surface of the melt, it was evaporated or volatilized. The rate of dissolution of the volatilized coal decreases as the carbon concentration approaches saturation or the equilibrium value of 5.4 % in the Fe-C system at 1593 ° C. It is therefore advisable to use a low carbon concentration in the bath to achieve a high dissolution rate. On the part of the inventors, a concentration of approximately 1-3 % of dissolved carbon in the carbon solution zone is preferred.

The maximum speed of resolution that can be achieved with these materials was achieved "was 0.13%. carbon per" minute for the coal having a grain size of -30 mesh with essentially no carbon initially dissolved in the bath. The maximum contact area of a stick of 569 cm was less than the minimum area of

ο
888 cm for the coal particles. This minimum area for coal

509811/0892

vmrde than the horizontal furnace cut on the surface of the melt calculated. That explains why the average speed of solving the volatilized coal was larger than that of the graphite rods. The higher dissolution rate with the help of the -30 mesh charcoal versus the -8 mesh charcoal may be due in part to the large difference between the outer surface areas of both materials can be returned. As a result, a particle size for the coal becomes no more than -30 mesh preferred.

The Kbhlenstofflösungsgeschwindigkeit metal should be maintained at about 1.12 to 2.20 kg of coal per minute per ton and the oxygen should Eindüsgeschwindigkeit / are in the range from 4.2 to 8.4 min Hur E ^e tonne of metal bath. Oxygen or steam or mixtures of these substances can be injected below or above the surface of the molten metal. If steam is used, additional heat should be applied, which can be done using a conventional electric furnace such as a resistance or induction furnace.

The inventive method for converting coal into a Combustible gas therefore provides the following individual steps:

a) the coal is pulverized.

b) The pulverized coal is sprayed into a first zone of a molten iron bath which contains 1-3 % of dissolved carbon, whereby the carbon content is increased to 3-5 % .

c) A second zone of the bath with a concentration of carbon of at least 3% is brought into contact with an oxidizing medium in the form of oxygen or steam and

509811/0892

d) a mixture of hydrogen and carbon monoxide is collected from it in a ratio of hydrogen to carbon monoxide of 2: 5 "to 10: 1.

The invention results in a high quality flow of a combustible gas, which is a partitioned reaction chamber for molten metal originates, the carbon being dissolved in the first section of the bath and oxidized in the other section. The rate of dissolution of the carbon (coal) is below under these conditions considerably, since maximum solution speeds can be achieved without being adversely affected by the reaction of carbon oxidation.

The invention is not limited to the exemplary embodiments described limited, since these only serve to explain the invention, all from the description, the drawing and the claims apparent features and advantages of the invention, including details of construction, spatial arrangements and procedures can be essential to the invention both individually and in any combination.

50981 1/0892

Claims (10)

Patent claims 1. Process for converting "coal into a combustible gas, dadurGh marked that a) pulverizes the coal, b) the pulverized coal is injected into a first zone of a molten iron bath containing 1-3% of dissolved carbon, the carbon concentration being increased to 3-5%, that c) a second zone of the molten bath, which has a carbon concentration of at least 3% , is brought into contact with oxygen or steam as the oxidizing agent and d) thereof a mixture of hydrogen and carbon monoxide in a ratio of hydrogen to carbon monoxide from 2: 5 to 10: 1 is absorbed. 2. The method according to claim 1, characterized that the coal is powdered to an average particle size not larger than 30 mesh. 3- The method according to claim 1, characterized that the coal is injected pneumatically. 4. The method according to claim 1, characterized that the coal is injected in an amount of 1.12 to 2.26 kg per minute per ton of iron in the bath. 509811/0892 5- The method according to claim 2, characterized that the bath zones are arranged separately from each other in such a way that the molten iron van der kohl enst offarm Zone in which the carbon is injected can flow into the carbon-rich zone in which oxygen is injected will. 6. The method according to claim 1, characterized that the coal is dried before the injection. 7- The method according to claim 1, characterized in that ratios of hydrogen to carbon monoxide of 1: 1 "to ~ $: Λ are maintained. 8. The method according to claim 1, characterized that the bath thereby with the oxidizing agent is brought into contact that the latter is injected below the surface of the molten iron. 9. The method according to claim 1, characterized that oxygen is introduced into the second zone of the bath in an amount of 4.2 to 8.4 iTnr / min per ton of iron in the bath is injected. 10. The method according to claim 1, characterized in that steam is used as the oxidizing agent and that the bath is heated by means of an electric furnace. 509811/0892