FR2507588A1 - PROCESS FOR REFORMING RAW GAS FROM COAL - Google Patents

Abstract

A crude gas obtained from coal and containing 6 to 30% by volume of methane, such as, for example, coke oven gas, is reformed with steam, by introducing it into a gasification zone while maintaining it at the high temperature at which it has been produced, without subjecting it to a cooling treatment for separating off and removing the higher hydrocarbon compounds such as, for example, the tarry constituents contained therein, or to a treatment for removing constituents other than the solid impurities. The crude gas is contacted with a sintered catalyst, which contains calcium oxide and aluminium oxide, in the presence of steam. This gives a hydrogen-enriched gas from the crude gas by the effective gasification of methane, straight-chain lower hydrocarbons and higher hydrocarbon compounds, which are contained therein.

Description

"Process for reforming raw gas from coal".

 The present invention relates to a process or treatment for reforming raw gases from coal, according to which a gas which is remarkably rich in hydrogen is produced by a simplified process with high thermal efficiency.

 Raw gases from coal contain various kinds of by-products and impurities. An example of such raw gases is coke oven gas. According to the known technique, such crude gases are subjected to purification treatments. During the purification treatment, the bituminous product is first separated from the gas by cooling and then successively and individually separated therefrom naphthalene, ammonia, sulfur compounds, benzene, cyanide and the like. The clean gas thus purified and the components which have been separated are used respectively in various uses. There are two usual purification methods for the case where the purified gas is to be used as a hydrogen-rich synthesis gas. In the first method, the purified gas is compressed and, after extracting the carbon dioxide, the hydrogen and the latter is recovered by the cryogenic separation process. According to the second process, after compression, gasification is carried out by the steam reforming or partial oxidation process. In the second process, there is no known suitable process for the direct reforming of unpurified raw gas from coal, even though the raw gas contains certain components which can be transformed into components of the desired synthesis gas. ; the reason is that no suitable catalyst is known for this type of steam reforming process.

With regard to the gases obtained by coal gasification, on the other hand, the usual method is that the gas obtained in the coal gasification apparatus is first of all cooled to separate the bituminous material which it contains, if the gas is to be used as synthesis gas, because the gas from the gasification apparatus contains bituminous material and the like, as is the case with coke oven gas. thus separated must be gasified separately by the partial oxidation process, and therefore it requires a complicated process to transform the bituminous material into a synthesis gas
As a result, such conventional methods intended for the treatment of raw gases from coal involve, in the known technique, as appears from the description above, the problems that
a) the process is inevitably complicated and the investment, necessary for the equipment intended for the implementation of the process, is increased by the fact that numerous pre-treatment stages are necessary to extract the various components and by the fact that means must be provided for the separate gasification of the bituminous material by partial oxidation or the like, if an improvement in the manufacture of the products is to be obtained, and
b) the thermal efficiency of the process is, undesirably, very low, due to the significant loss of energy which occurs as a natural consequence of the phases which are involved, such as the initial cooling of the raw gas and the subsequent reheating gas for the following phases.

The inventors have done intensive research in order to overcome the problems described above of the processes of the known art. The inventors have discovered that when the raw gas is subjected to gasification of the impurities with an appropriate control of the amount of vapor. contained in the gas, using a sintered catalyst composed of calcium oxide and aluminum oxide, while keeping the crude gas treated the same high temperature as it had when it left the coal gasifier and without extracting the gaseous impurities, it is possible to obtain an effective gasification of the bituminous material, of the
naphthalene, benzene, ammonia, cyanide, compounds
sulphides and similar components in raw gas
treated, as well as a gasification of aliphatic hydrocarbons such as methane, ethane and the like, all of this contributing to producing a gas rich in hydrogen. Furthermore, the process according to the invention has the unexpected advantage that it does not cause no significant poisoning of the catalyst.

The present invention provides an improved process for treating raw gas from coal
The raw starting gas from coal is at a temperature of the order of 300 to 9000C and at a pressure varying from atmospheric pressure to I 0 MPa and contains from 6 to 30% by volume of methane, as well as d other low molecular weight aliphatic hydrocarbons and high carbon components These gaseous impurities in the raw gas are gasified by introducing the raw gas from coal into a gasification zone, the raw gas being kept at the high temperature it when he left the coal gasifier, without subjecting the raw gas to a cooling treatment intended to separate and extract the high carbon compounds it contains and without subjecting it to a treatment to extract components other than solid impurities In the gasification zone, the raw gas comes into contact with a sintered catalyst consisting of 10 to 60% by weight of calcium oxide and 40 to 908 by weight of oxide of alum inium, at a temperature between 800 and 1,300 C, in the presence of a gasification agent.

 An object of the present invention is to provide a method for producing a hydrogen-rich gas by carrying out a reforming treatment on a crude gas from coal, a process in which the process is simplified by the omission of the usual, pre-treatments, c that is to say without extracting the high carbon compounds contained in the gas by a cooling treatment and without any purification treatment other than the removal of solid dust.

 Another object of the invention is to provide a process by which a hydrogen-rich gas is obtained with a high production by means of the reforming treatment of a raw gas coming from the coal as such, without employing separation phases individual or the extraction of bituminous material, naphthalene, ammonia and the like; in this process, a direct gasification of the bituminous material and similar impurities is obtained concurrently.

 Yet another object of the invention is to provide a process for the reforming treatment of a raw gas from coal, a process which has a high overall thermal efficiency due to the elimination of the gas cooling phases with a view to the separation and extraction of high carbon compounds followed by reheating, phases which were inevitable in conventional methods which include the treatment of purification of raw gas from coal.

 A further object of the invention is to provide a method for the. reforming treatment of a raw gas from coal, a process which can be carried out with a much lower investment than in the processes known in the prior art, due to the simplicity of the process according to the invention.

Other characteristics and advantages of the invention will emerge from the description which follows, given by way of illustration with reference to the attached drawings, in which:
FIG. 1 is a diagram illustrating the progress of a conventional process for treating coke oven gas, and
- figs. 2 and 3 are diagrams illustrating the flow of operations of two processes for the reforming treatment of a raw gas from coal in accordance with the present invention.

 In the remainder of the description and in the claims, the term "high carbon compounds" refers to materials including bituminous material, benzene, naphthalene, phenols, anthracene and the like, and the term "low hydrocarbon "denotes hydrocarbon compounds having at most four carbon atoms in the molecule.

 The raw gases from the coal to be treated by the process according to the present invention include the gases which are called coke oven gases, discharged from a coke oven and the gas obtained from a coal gasification apparatus, l The invention is not however limited to these two examples. It is equally possible to use all types of raw gas from coal provided that the initial methane content, temperature and pressure are within the limits which have been indicated above. The composition of the raw gases may differ somewhat from one gas to another; conventionally, a coke oven gas has a composition as described in Table 1.

Components Table 1 Proportions
Methane 10 to 40 mol%
Ethane and ethylene 1 to 5 mol%
Hydrocarbons CnHm * O at 2 mol%
Carbon dioxide 1 to 5 mol%
Carbon monoxide 2 to 10 mol%
Hydrogen 40 to 70% by moles
Hydrogen sulfide 0 to 1 mole%
Nitrogen 0 to 6% in moles
Oxygen 0 to 1% in moles
Tar 100 to 150 g / Nm3
Benzene, toluene and xylene fractions 30 to 50 g / Nm3 * Aliphatic hydrocarbons other than methane, ethane,
and ethylene.

Components (continued from Table 1) Proportions
Naphthalene 1 to 2 g / Nm3
Ammonia 5 to 10 g / Nm3
Hydrocyanic acid 1 to 2 g / Nm3
Nitric oxide 0 to 5 mg / Nm3
Organic sulfur 0 to 500 mg / Nm3
This coke oven gas is generally obtained at a temperature of 600 to 18000C, typically at around 7000C, and this gas is approximately at atmospheric pressure.

 The gases supplied by the gasification of coal, for example in a counter-current and moving bed coal gasification apparatus, generally have a composition within the ranges indicated in Table 2 below.

Components Table 2 Proportions
Methane 6 to 30% by moles
Ethane 0 to 2 mol%
Hydrocarbons CnHm 0 to 1% in moles Carbon dioxide 25 to 40% in moles
Carbon monoxide 10 to 25 mol%
Hydrogen 30 to 45% by moles
Hydrogen sulfide 0 to 1 mole%
Nitrogen 0 to 2 mol% oxygen 0 to 0.5 mol%
Tar 10 to 150 g / Nm
Benzine, toluene and xylene fractions and 10 to 100 g / Nm3
Naphthalene ammonia 0 to 1 mol%
Cyanydric acid 0 to 1 mol%
Nitric oxide 0 to 0.1 mol%
Organic sulfur 0 to 0.1 mole%
Water vapor (molar ratio to dry gas) 0.5 to 1.0.

 Such gases obtained by coal gasification contain considerable amounts of water vapor, so that in most cases it is not necessary to add steam to the initial raw gas when using a gas. obtained directly from a process of gasification of the good tank in the method according to the present invention.

 This raw gas is obtained at a temperature which is generally between 400 and 700au at various pressures which are generally between 1 and 3 MPa.

 For the implementation of the process according to the present invention the addition of steam to the gasification zone is necessary when the raw gas is a coke oven gas whereas, as mentioned above, the addition of steam can be omitted in the majority of cases when using a raw gas obtained by gasification of coal.

 The mixing of the steam with the coke oven gas can be carried out by any usual process, this process not being particularly limiting of the invention. A particularly preferable procedure for the introduction of the gaseous mixture constituted by the coke oven gas and the steam into the catalytic gasification zone uses a steam injector to suck up the coke oven gas which is approximately at atmospheric pressure and to increase the pressure of the gas mixture to bring it to a super-atmospheric pressure using steam as the working fluid. In this way, one can gently introduce a coke oven gas at atmospheric pressure - into the gasification zone even if the gasification zone is at high pressure. For example a gaseous mixture of coke oven gas and steam at the temperature of 200 to 1000au and at a pressure of 0.2 to 3 MPa can be obtained by using steam at a temperature of 200 to 1 0000C and at a pressure of 0.2 d 1 0 MPa as the working fluid.

The quantity of vapor used as a gasification agent present in the gasification zone according to the process according to the invention depends on the performance of the gasification catalyst as well as on the use that is to be made of the gas which will be produced. In general, steam is supplied in a way
to maintain the molecular ratio 'H2O / C in the field of
1 to 7 preferably from 2 to 4. An amount of steam exceeding
the upper limit of this domain leads to a decrease in
economic benefits while using less steam
lower than the lower limit decreases the gas yield
fication.

In the process according to the present invention
tion, methane, other low aliphatic hydrocarbons and
high carbon compounds present. in the gas
crude-from coal and introduced into the gasification zone
cation, are transformed or carbonated, in the presence of cats1yseurr
into hydrogen, carbon monoxide and carbon dioxide by
endothermic reactions that require supplied heat
either by an internal heating system or a heating system
external fage. Such a heating system can easily besides
obtained using a known procedure.

When using a heating system
internal age with addition of an oxidizing agent so as to oxidize
the combustible components of the raw gas we can use as
oxidizing agent a gas containing molecular oxygen, such
than gaseous oxygen or air. When using as-
raw gas from coke oven gas, supply of gas containing o
Molecular oxygen is controlled in such a way that the pressure is maintained in the range of 0.2 to 3 MPa, that the temperature
ture is in a range from 30 to 8000C and that the molecular ratio
02 / C is between 0.2 and 1.0, preferably without
exceed 0.5. O2 / C molecular ratio higher than the limit
above indicated by 10 leads to a decrease in
economic benefits, while a lower molecular ratio
at the lower limit of 0.2 is not desirable because an appropriate heat balance cannot be obtained in the reaction
tion. 4
In the method according to the present invention
the reaction temperature in the catalyzed gasification zone
tick is kept between 800 and 13000C, preferably between 900 and 1100C. When the reaction temperature is below 8000C, the gasification yield is reduced and the continuous operation of the reaction becomes difficult, due to the deposition of carbon on the catalyst. No particular additional advantage is obtained by carrying out the reaction at a temperature above 1300 "C and such high temperatures are economically disadvantageous
The pressure in the catalytic gasification zone during the reaction is not particularly limited, but it depends somewhat on the type of raw gas which is used The pressure is generally at least 0.1 MPa and preferably in a range 0.2 d 3 MPa.

 In addition, the space velocity of the drafting gases in the area; gasification is generally maintained in the range of 500 to 10,000 / hour, preferably of.

2,000 to 5,000 / hours. o
The catalyst used in the process according to the present invention is a sintered catalyst consisting of 10 to 60% by weight of calcium oxide and 40 to 90% by weight of aluminum oxide. Suitable sintered catalysts are described in US Pat. No. 3,969,542. This catalyst can contain one or more types of alkaline alkali metals. the form of strontium oxide, beryllium oxide, magnesium oxide and analogs, but what is critical is that the proportion of silicon oxide is not more than 0.5% by weight. This catalyst can be prepared according to the method described in the aforementioned American patent N03,969,542.

 The mixture to be used in the preparation of the catalyst consists of a refractory powder of calcium aluminate and of one or more types of compounds chosen from the group consisting of aluminum oxide, beryllium oxide, l 'calcium oxide, magnesium oxide and strontium oxide as well as the compounds which can form oxides by heating each of these opposites' having a sufficient purity to ensure that the proportion of silicon oxide in the catalyst obtained is 0.5% by weight or less. Alternatively, a refractory powder of calcium aluminate can be used on its own, but in both cases there must be a proportion of at least 10% by weight of calcium oxide in the catalyst obtained. The catalyst is prepared by kneading the powder mixture described above or the refractory powder of calcium aluminate by adding water and, optionally, a binder as required; this is followed by molding and calcination at a temperature of about 1 1500C or more.

 It is also possible to accelerate the gasification reaction of the impurities contained in small quantity in the raw gas coming from the coal when the sintered catalyst mentioned above essentially composed of calcium oxide and aluminum oxide is used in combination with a ca sintered ternary catalyst of calcium oxide, aluminum oxide and nickel oxide. This ternary catalyst is a sintered catalyst comprising for example in composition from 2 to 60% by weight of calcium oxide, from 10 to 70% by weight of aluminum oxide and from 10 to 30% by weight of oxide of nickel as sella is described in American patent N04 101 449. These catalysts can be prepared for example by kneading a mixture of nickel oxide, calcium oxide and aluminous cement in the proportions ddsirdes by adding water; this is followed by molding, curing by hydration and calcination of the cured material at a temperature between 550 and 12000C. It is also critical that the content of silicon oxide in these latter catalysts is at most 1% by weight.

 In the process according to the present invention, the raw gas from the coal undergoes partial oxidation or a steam reforming reaction in the presence of a catalyst consisting of a sintered material based on calcium oxide. As a result, the aliphatic hydrocarbons, such as methane, ethane and the like, contained in the gas are gasified in the form of hydrogen, carbon monoxide and carbon dioxide. Simultaneously other impurities such as bituminous material are also gasified, so that impurities other than sulfur compounds disappear substantially.

 In particular, the sintered catalyst consisting of calcium oxide and aluminum oxide which has been described above, is above all effective for the gasification of the heaviest fractions, such as tar and the like. , without carbon deposition on the surface of the catalyst, whereas the ternary sintered catalyst constituted by calcium oxide, aluminum oxide and nickel oxide is above all effective for the gasification of light hydrocarbons, such as methane, ethane and the like, despite carbon on the surface of the catalyst, even in the presence of sulfur compounds.

The composition of the gaseous product at the exit from the gasification-catalytic zone in the process according to the invention is determined by the equilibrium in the following two reactions as well as by the activity of the catalyst.
CH4 + H2O 3H2 + CO (methane reforming)
CO + H20 H2 + CO2 (decomposition of CO)
The gasification reaction according to the present invention generally produces a hydrogen-rich gas at an elevated temperature of 800 to 1100C and at a superatmospheric pressure of 0.2-3.3 MPa. The gaseous product is transmitted to a subsequent process after heat recovery in a known manner.

 Preferred embodiments of the method according to the invention are described below with reference to the drawings and in conjunction with a description of a conventional process presented for reasons of comparison.

 4 Fig. 1 is a diagram showing the progress of a conventional process for treating a coke oven gas. The coke oven gas is sent from a cokel oven to a water-cooled condenser 2, where the bituminous material contained in the gas is separated from it. Then, the gas passes successively through a direct cooler 3, a compressor 4, a naphthalene separator 5, a desulfurization apparatus 6, an ammonia washer 7 and a benzene absorption column 8 in order to extract respectively naphthalene, sulfur compounds, ammonia and benzene. The coker gas which has been treated in this way is, when intended to be used as a gas for the synthesis of ammonia, compressed in a compressor 9 , reheated in a heater 10, and finally desulfurized in the desulfurization device 17. Then, after having been mixed with steam 16, the pre-treated coke oven gas is sent through the gasification device 12 which is filled with a conventional steam reforming catalyst and in which the coking plant gas is gasified and transformed into a gas 18 rich in hydrogen after having been mixed with air or oxygen 17 which is been introduced via a compressor 13 and a heater 14. A recovery boiler 15 is provided for recovering thermal energy.

 Fig. 2 is a diagram showing the flow of the process for the reforming treatment of a raw gas from coal in accordance with the present invention, using a process intended for the treatment of a coke oven gas in a gasification apparatus with internal heating, this as an example. Coking gas from the oven.

to cokel is collected in a collecting tube 21, so as to have approximately a constant composition, and the raw gas which does not undergo any pretreatment is maintained at the same high temperature as it had when it left the coke oven . After removal of solid materials such as dust, as necessary, in a dust collector 22 such as a cyclone separator, the coke oven gas is then introduced into the steam injector 24 via of the pipe 23. The pressure of the coking plant gas is increased in order to bring it to a super-atmospheric pressure in the injector 24, the coking plant gas being sucked up by the high pressure steam supplied by the pipe 25 and constituting the working fluid, the gas being mixed with steam so as to produce a gaseous mixture of coke oven gas and steam.

 This gaseous mixture of coke oven gas and steam which has just been prepared in this way is then introduced via the line 26 into the gasification apparatus 27 which comprises an upper combustion zone 27A and a catalyst bed 27B. Air or oxygen is introduced into the gasification device 27 via the line 30, the air or oxygen having been pressurized and preheated in the compressor 28 and the heater 29 , respectively. The coke oven gas is then gasified by passing through the catalyst bed 27B and the gaseous product thus obtained, which is rich in hydrogen, is extracted from the gasification apparatus 27 in its lower part via the pipe 31. After the heat has been recovered in a heat recovery unit 32, the gaseous product is extracted via the conduit 33. This gas can however be subjected to a subsequent desulfurization treatment.

 Fig.3 is a diagram showing the flow of an embodiment of the method according to the invention intended for the treatment of a raw gas obtained by the gasification of coal using a tubular coal gasification apparatus 34 with heating outside. The raw gas from the coal gasifier, which is kept at the same high temperature as it had when it left the gasifier 34, is introduced into a second externally heated gasifier 37 after been subjected to a dust extraction in a dust collector 36 installed on the pipe 35. the raw gas then passes through the catalyst tube 39 which is filled with the catalyst 38. This catalyst tube 39 is made of a resistant material to heat and it is heated externally, so as to provide an amount of heat sufficient to cause the reaction. Line 40 is provided to supply the fuel used for external heating. from the catalyst tube 39. The gaseous product enriched in hydrogen, which is obtained by the contact treatment with the catalyst 38, is sent to a heat recovery unit 42 via a pipe 41, the waste heat is recovered and the gaseous product is then extracted via the pipe 43. The diagram in FIG. 3 includes a duct 44 for the second gasification device, a heat recovery system 45 for the second gasification device, a fan 46 and an exhaust manifold 47.

 As described above, a raw gas from coal and obtained directly from a coal gasification process is gasified, in accordance with the method according to the present invention, without carrying out purification of the raw gas for the purpose of effective removal of impurities (by-products) and that is why it is kept at the same high temperature as it had when it left the coal gasifier 34. In this process, in particular, the gas crude from the high temperature coal gasifier is not cooled or refrigerated, so there is no need to reheat the gas for its subsequent catalytic gasification. For this reason, the thermal efficiency of the process according to the present invention is excellent, and the process is greatly simplified, so that the investment required for the equipment used for the treatment of raw gases derived from coal is much lower compared to the processes conventional dice. In addition, the gaseous product is at a high temperature after gasification and it can be subjected without difficulty to heat recovery by the usual means, so that a satisfactory thermal yield is obtained.

 In addition, in the methods of. -the prior art in which a coke oven gas was used as the initial raw gas, there was the problem that the power consumption downstream of the reforming process was unacceptably increased in the case where high pressures, made of the increase in volume caused by gasification. The problem can be alleviated by installing a steam injector before the gasification zone as is done in the process according to the present invention. The vapor necessary for the gasification is introduced into the gasification zone so as to constitute the working fluid of the injector for mixing with the coke oven gas, this addition of steam also creates a pressurization of the coke oven gas at a sufficiently high pressure, so that the coke oven gas and the steam are sent to the gasification zone in high pressure conditions. In addition, the vapor injection device makes it possible to improve the gasification reaction at high pressure, so that the yield of the catalyst is increased and the quantity of catalyst in the reactor can thus be reduced.

 The hydrogen-enriched gas produced according to the present invention is suitable for use as a synthesis gas for ammonia or methyl alcohol, as a hydrogen gas and / or as a starting reactive gas for what I the methods of synthesis of the chemistry of compounds are called a carbon atom, as well as as a combustible gas.

 The present invention is described in detail below by way of illustrative examples.

EXAMPLE 1
A coke oven gas was subjected to the reforming treatment according to the present invention, in accordance with the pro.

cessus described by the diagram in fig. 2. The coke oven gas was produced in the coke oven 20 and was collected in the collecting tube 2 at a rate of 108,770 Nn3 / hour with respect to the volume of the dry gas. The coke oven gas was at a temperature of 700 "C and at atmospheric pressure. The composition of the gas expressed in hourly flow rate, in kg / h for each of the components was as follows
Components Hourly flow rate (kg / h)
Methane 23,430
Ethane 3,640
Carbon monoxide 5,940
Carbon monoxide 9,250
Hydrogen 5,210
Nitrogen 1,570
Oxygen 600
Hydrogen sulfide 320
Ammonia 870
Hydrocyanic acid 190 Frs. = Mitns of benzene, toluene and xylene 4,000
Naphthalene 150
Bituminous material 12,000
Organic sulfur 10
Nitric oxide (2 ppm)
TOTAL 67,180 kg / h
The coke oven gas was introduced into the dust collector 22 in order to extract the dust contained in the gas and it was then entrained via the line 23 in the steam injector 24 which was constituted by a gas injector. two floors. 122 tonnes / h of steam at a temperature of 7000C were introduced into the steam injector.

The steam was supplied in two parts, the first part being 61 tonnes / h at a pressure of 25kg / cm2 G. for the first stage, and the second part being 61 tonnes / h at a pressure of 6 MPa for the second floor. The pressure of the gas mixture which was introduced into the gasification device 27 via the line 26 was 0.5 MPa at the outlet of the injector 24. Gaseous oxygen was introduced into the gasification device 27 via the intermediate line 30 with a flow rate of 31,000 Nm3 / h after having been pressurized in the compressor 28 at a pressure of approximately 0.6 'MPa and after having been heated in the heater 29 at a temperature of 2380C. The gasification reaction was carried out in the gasification apparatus 27 at a temperature of about 9800C under the conditions indicated below
a) Pressure: 0.5 MPa
b) catalyst: two types of sintered catalysts were used, one consisting of 50% by weight of calcium oxide and 50% by weight of aluminum oxide, and the other consisting of 42.5 % by weight of calcium oxide, 42.5% by weight of aluminum oxide and 15% by weight of nickel oxide; these two catalysts were used in equal amounts to fill the catalyst bed 27B of the reactor as two separate layers. The volume of the catalyst was 150 m for a space speed of 2,500 / h.

 c) H2O / C ratio; 2.0.

d) ratio 02 / C: 0.42
e) space speed: 2,500 / h at the outlet of the gasification device 27.

The composition of the gaseous product thus obtained was as follows:
Gas volume (dry gas) 245,680 Nm / h
Component Proportion% one moles
Hydrogen 68.6 mole% Carbon monoxide 21.0%
Carbon dioxide 9.2%
Methane 0.1%
Nitrogen 0.8%
0.1% hydrogen sulfide
0.2% Argon
Water content 129,520 Nm / h
In order to efficiently recover the heat from the outlet gas which was at a temperature of 900 C, this heat was used in the heat recovery unit 32 to produce steam with a flow rate greater than the flow rate of the steam supplied to the The gasification operation was continued as described above for approximately 4,500 hours without any significant contamination of the catalyst in the catalyst bed occurring by carbon deposition occurring.

EXAMPLE 2
The gasification reaction was carried out in substantially the same manner, that is to say with the same coke oven gas under the same reaction conditions in accordance with the diagram in FIG. 2 as described in Example 1, except -.

tion that the catalyst bed was formed of a single layer of 70 m 'of the sintered catalyst consisting of calcium oxide and aluminum oxide used in Example 1, instead of the catalyst bed two layers and that the flow rate of oxygen blown into the gasification device 27 through the line 23 was 23,000 Nm3 / h. The composition of the outlet gas extracted from the gasification apparatus was as shown below.

No significant contamination of the catalyst bed was observed by carbon deposition in this case as in the case of Example 1, even after extensive continuous operation of the reaction.

Output gas: 0.5 MPa pressure at 1010 C
Components Proportion% in moles of hydrogen 62.2%
Carbon monoxide 17.1%
Carbon dioxide 10.3%
Methane 9.2%
Nitrogen 1.0%
0.1% hydrogen sulfide
Argon r 0.1%
Water content 134,040 Nm / h.

EXAMPLE 3
Gas having the same composition and at the same flow rate as described in Example 1 was mixed with steam and treated in an externally heated tubular gasification apparatus having a heating capacity of
0.6239 10 J. The externally heated tubular gasifier was filled with the same catalyst as that used in Example 1 and the amount of steam added was also the same as described in Example 1.

 The composition of the outlet gas thus obtained from the tubular gasification apparatus with external heating was analyzed and the results obtained are shown below.

 No significant carbon deposition was noted on the catalyst in this case, even after 4000 hours of continuous operation.

Exit gas: 9.5 MPa pressure at 9009C
Gas volume (dry gas): 294,300 Nm3 / h
Components Proportion% in moles
Hydrogen 74.0
Carbon monoxide 17.6
Carbon dioxide 6.7
Methane 1.0 nitrogen 0.6
Hydrogen sulfide 0.1
Argon
Water content 112,230 Nm3 / h
EXAMPLE 4
An internal heating type catalytic gasification device was used having a structure similar to that of the gasification device described in the diagram in fig. 2 and the gas obtained by gasification of coal was treated in this gasification device. by the partial oxidation process. The catalyst used in the catalytic gasification apparatus was the same as that described in Example 1. The raw gas extracted from the coal gasification apparatus was at a temperature of 400 ° C. and at a pressure of 2 MPa and its flow rate was 172,030 Nm3 / h, this flow rate being calculated by volume of dry gas. The composition of the raw gas was as indicated below in hourly flow rate for each of its components.

Methane 14,880 kg / h
Ethane 2,150
Carbon dioxide 96,650 Carbon monoxide 43,440
Hydrogen 5,820
Nitrogen 860
Hydrogen sulfide 290
Bituminous material and phenols 9 570
TOTAL 173,660 kg / h
Water content 157 650 Nm3 / h
The gas described above produced by gasification of coal was introduced into a catalytic gasification apparatus via a dust collector and was gasified in the gasification apparatus with simultaneous introduction of heated oxygen. 2380C with a must of 33,000 -Nm3 / h.

In this way, an outlet gas was obtained at a temperature of 9000C at a pressure of 2.5 MPa
Its composition was that indicated below. No significant carbon spite was observed on the catalyst even after continuous operation of about 4000 h.

Gas volume (dry gas) 227 100 Nm3 / h
Components Proportion% in moles
Hydrogen 44.9
Carbon monoxide 22.4
Carbon dioxide 26.5
Methane 0.5
Nitrogen 0.4
Hydrogen sulfide 0.1
Argon 0.2
Water content 137 180 Nm3 / h.

Claims (5)

 10) Process for continuous catalytic steam reforming, intended for the preparation of a hydrogen-rich gas from a raw gas coming from coal, said raw gas containing from 6 to 30% by volume of methane and being at a temperature of 300 to 9000C and at a pressure between atmospheric pressure and a pressure of 10 MPa - -, said process being characterized in that it comprises the steps of:  introduction of said raw gas into a steam reforming catalytic gasification zone, said raw gas being maintained continuously at said high temperature without being subjected to a cooling treatment for the separation and extraction of gaseous carbon compounds high molecular weight contained in said raw gas or -to a treatment for the extraction of other gaseous impurities from said raw gas;  contacting said raw gas in said gasification zone in the presence of steam which acts as a gasification agent, with a sintered catalyst consisting essentially of 10 to 608 by weight of calcium oxide and from 40 to 908 by weight of aluminum oxide, having a silicon oxide content of at most 0.5% by weight, at a temperature between 800 to 1300C, so as to carry out a steam reforming reaction to transform W.Sthane, low hydrocarbons and high :: molecular carbon compounds contained in said raw gas as hydrogen, carbon monoxide and carbon dioxide;  recovery of a hydrogen-rich gas from said gasification zone, said gas being substantially freed from the initial impurities other than the sulfur compounds, so that said catalyst remains essentially free of carbon deposition.  20) Method according to claim 1, characterized in that said raw gas from coal is coke oven gas or gas produced by gasification of coal.  30) Method according to claim 1, characterized in that the spatial speed of said raw gas introduced into said gasification zone is of the order of 500 to 10,000 / h.  40) Method according to claim 1, characterized in that said raw gas is also brought into contact, in the presence of said vapor, with a second sintered catalyst consisting mainly of 20 to 60% by weight of calcium oxide, from 10 to 70 % by weight of aluminum oxide and from 10 to 30% by weight of nickel oxide, and containing at most 1% by weight of silicon oxide.  50> Method according to claim 1, characterized in that a steam injector is arranged in communication with said gasification zone, in that said raw gas is introduced into said steam injector and in that the pressure of said raw gas is increased by a f-lux of steam comprising the working fluid of said steam injector, a gaseous mixture consisting essentially of said raw gas and said steam being introduced under pressure therein into said gasification zone, said steam constituting the agent gasification  6) Process according to claim 1, characterized in that the quantity of said vapor uses RD as a gasification agent is sufficient to provide a molecular ratio of the total water relative to the carbon in said raw gas (H20 / C) between 7 and 7.  70) Method according to claim 1, characterized in that said gasification zone is internally heated.  80 ') Method according to claim t, characterized in that the reaction pressure in said gasification zone is at least 0.1 MPa  9 ") Method according to claim 1, characterized in that the gasification zone is externally heated.  10) Method according to claim 5, characterized in that said raw gas is coke oven gas obtained from a coke oven immediately before being introduced into said steam injector.  110) Method according to claim 10, characterized in that oxygen containing oxygen is injected into said gasification zone simultaneously with said gas mixture, said oxygen-containing gas being at a pressure between 0.2 and 3 MPa and at a temperature of 30 to 800 ° C, such that the molecular ratio of oxygen to carbon in said gas mixture is between 0.2 and 1.0.  12) Method according to any one of claims 1 and 10, characterized in that said catalyst contains or several alkali-ferrous metals.