DE1274270B - Method for producing a fuel gas - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Intel .:

Clog

German class: 26 a - 12

Number: 1274270

File number: P 12 74 270.0-44 (C 33036)

Filing date: June 3, 1964

Open date: August 1, 1968

The invention relates to a method of manufacture a fuel gas containing carbon dioxide, carbon monoxide, ethylene, methane, hydrogen and nitrogen by steam reforming a hydrocarbon. According to the method according to the invention Heavy gasoline (naphtha) by suitable choice of different, interrelated Process variants gasified without the simultaneous formation of free carbon. The reaction of Heavy gasoline with steam and air is directed in such a way that a raw gas flow arises, which is an essential one Proportion of low hydrocarbons as well as carbon monoxide and hydrogen contains. Unsaturated lower hydrocarbons are optionally hydrogenated, so that a stable Town gas is generated.

Heavy gasoline (naphtha) is a relatively volatile refining product or intermediate product of petroleum, which is generally defined in terms of the boiling range. According to an overview of crude oil in Industrial and Engineering Chemistry, 44, 11 (November 1952), p. 2578, naphtha is defined as follows: The naphtha content (of crude oil) corresponds to the total distillate that is found in the routine analysis of the US Bureau of Mines * 5 at a steam temperature of 200 ^° C. «A more detailed definition of naphtha has appeared in» Petroleum Refining with Chemicals «by Kalichevsky and Kobe (1956). A discussion of naphtha on pages 21 to 23 of this reference shows that various naphthas boiling ranges can have a maximum of 204 ⁰ C of a lower limit of ⁰ C to 5O. Accordingly, "naphtha" is defined as a general term that is applied to fractions that boil in the gasoline and low kerosene range. In general, naphtha is a low-boiling and highly volatile liquid hydrocarbon fraction that is obtained in crude oil refining during the distillation of crude oil. The material consists mainly of straight-chain C 5 to C 9 paraffins, but up to 30% naphthenic compounds together with up to 10% aromatic and unsaturated compounds can still be present. In addition, naphtha generally contains a significant amount of sulfur in the form of COS and mercaptans.

The production of town gas from heavy gasoline (naphtha) is described in British patent specification 923 385 described. This process uses heavy fuel (naphtha) or a »light distillate« Steam reformed in the presence of a specific catalyst composition, with the formation of Method for producing a fuel gas

Applicant:

Chemical Construction Corporation,

New York, N.Y. (V. St. A.)

Representative:

Dr. F. Zumstein, Dr. E. Assmann

and Dr. R. Koenigsberger, patent attorneys,

8000 Munich 2, Bräuhausstr. 4th

Named as inventor:

John Samuel Negra,

South Plainfield, N. Y .;

Arnold Robert Bernas, Nixon, N. J. (V. St. A.)

Claimed priority:

V. St. v. America 7 June 1963 (286 296)

free carbon, tar and smear is prevented. A cycle for the production of Fuel gas made from high-sulfur heavy gasoline (naphtha) is described in US Pat. No. 2,711,419. Preheated heavy gasoline vapor, air and water vapor are released in the presence of a catalyst Nickel type implemented. Accumulated carbon and sulfur deposited on the catalyst are removed by a regularly recurring burn-off period. According to the state The art used numerous other processes for catalytic or non-catalytic Gasification of heavy gasoline (naphtha) carried out. According to the method according to the invention Heavy gasoline (naphtha) with steam and air at elevated temperature to form a crude gasified combustible gas. After hydrogenation of unsaturated compounds becomes a finished town gas generated. In the gasification stage of the invention, a limited amount of process air is used, to promote the gasification of heavy gasoline (naphtha) and to act as a nitrogen gas component To ensure ballast in the finished town gas. The inventive method depends on a characteristic Equilibrium of the reaction conditions to achieve gasification of heavy fuel (naphtha) since this is effected without an accumulated deposit of free carbon. Besides, none is worth mentioning Amount of unreacted hydrocarbon present in the finished synthesis gas. The basic process is in a gasification conditioning step followed by a sudden cooling step carried out. It was found that the gasification

809 588/189

level must be short to prevent the gasoline vapor from becoming unstable, and certain proportions Reaction components reach equilibrium, or components can easily become smaller moIedas a deposition of free carbon in the cooler with simultaneous carbon deposition Catalyst bed results. There was also cracking. Through lines 3 and 7 the hard find is that the reaction components are preheated 5 gasoline vapor with a temperature in the range of 204 to 427 ° C must be to a minimum temperature level lying temperature of the Verweil- or Vergasungsim To enable gasification step. Accordingly, chamber 8 is supplied.

the heavy gasoline in the process according to the invention Through line 4, strongly overheated water

(Naphtha), steam and air preheated and steam, which is generally to a temperature of mixes. There is a partial conversion, and the io above 816 ° C and preferably up to the range of Mixture, which is now a large number of intermediate compounds 816 to 927 ° C preheated, fed. Though too fertilize, but this is not yet possible in the final reac- lower ratios has been found, equilibrium is deterred. That a range of molar steam carbon arises raw, flammable gas consists of a ratio between 3 and 6 is desirable Gas mixture, the methane, ethylene, hydrogen, nitrogen 15 to the relative flow rates of hydrogen, Contains carbon monoxide and carbon dioxide. vapor 4 and heavy gasoline vapor 3 in one such ver-das The gas mixture is essentially free of any inconvenience to ensure that the set hydrocarbons or solid carbon formation or increased deposition of carbon particles, substance under normal process conditions

The inventive method for production zo the is.

of a carbon dioxide, carbon monoxide, ethylene, Me- air, which is generally at a temperature of

Thane, hydrogen and nitrogen containing fuel is preheated to more than 427 ° C and preferably to a range of gases by steam reforming a hydrocarbon between 427 and 649 ° C, is introduced through line 5 by preheating vaporized carbon. The proportion of applied hydrogen, water vapor and air and reforming air is fairly low in the process according to the invention of the gas mixture, in particular in a reforming catalyst, since only enough air is used to catalyze the reforming, is that on a temperature desired thermal effects the heavy gasoline preheated by the temperature below 538 ° C to bring about the temperature (naphtha) of the heavy gasoline with superheated steam and a temperature increase. The air 5 and the heated air at a temperature of at least 30 water vapor are combined in line 6, whereby they are 538 ° C to a gas mixture with a molar combination of a mixed water vapor-air flow with a ratio of steam to carbon of 1, Form 5 to 6.0 and temperature of at least 593 ° C. The air is mixed from air to carbon from 0.1 to I ₃ O, the water vapor mixture in line 6 is now combined with this gas mixture for a period of less heavy gasoline vapor from line 3 and that for more than 1.0 second while increasing the temperature 35 mixture then immediately partially converted through line 7 into the residence at least 760 ° C and then passed or gasification chamber 8. It is also possible to lend the product obtained with a liquid coolant, to quench the heavy gasoline vapor 3, the water vapor 4 to a temperature below 427 ° C and to introduce the air 5 separately into the chamber 8, and if necessary the raw gas obtained - but that represents previous mixing of air and mixture with the addition of water, converted to a catalytic converter 40 water vapor to form the water vapor-air sensor from activated iron oxide, then mixture 6 is a preferred embodiment of the catalytically hydrogenated and the finished gas mixture process, as it is a better and faster washing with a liquid absorbent. mixing of the individual components. The process according to the invention has various important advantages. A fundamental advantage 45 of mixing with the steam-air is that the heavy gasoline (naphtha) full mixture from line 6 before the entry of the heavy in a stable, crude, flammable gas, without gasoline vapor in the residence chamber 8 faster simultaneous accumulation of free carbon or dispersed and diluted. As a result, the tar is converted by it. A circuit or prior mixing, the option of a bypass facility is not required. The pre-process, which is attributable to the cracking of heavy gasoline, is a continuous rather than a cyclic transient carbon formation or deposition or intermittent process. The procedure is diminished in the.

Gasification stage non-catalytic, as, however, in chamber 8 simultaneous conversions take place

shown below, a nickel catalyst can be used between and among the various reactions when considering the calorific value of the finished 55 components and interconnects instead. the Wants to increase city gas. The temperature in chamber 8 rises instantly,

The inventive method is based on what the exothermic combustion of part of the the drawing explained in more detail. In the drawing, heavy fuel is mixed with the oxygen content of the air liquid heavy fuel (naphtha), which is derived from the petroleum industry. In addition, part of the refining odei other types of processing of crude 60 heavy gasoline as a result of the high temperature below Oil was obtained, which mainly from paraffinic high water vapor concentrations in chamber 8 see hydrocarbons in the C-5 to C-9 range, non-catalytically steam reformed. The endothermic along with both naphthenic and minor reaction causes the formation of free hydrogen Amounts of aromatic and sulfur compounds and also dampens those caused by combustion consists, introduced through line 1 into the heater 2, 65 temperature increase. Another part of the Schwerdort evaporated and preheated. The heavy gasoline turns thermally into lower hydro vapor has a maximum temperature of about 538 ° C, which is also due to the high tempe-Above the temperature level can be attributed to this temperature level. Simultaneous disintegration

5 6

Deposition and accumulation of free carbon can be any suitable coolant, such as a stable one does not take place at the same moment, however. The heavy hydrocarbon oil or preferably something against it the unstable low carbons are introduced into the quenching unit 10 and through Hydrogen can be selectively withdrawn from line 12 to a certain extent. The cooled process

hydrogenated, reflecting the in situ formation of hydrogen, 5 rene gas mixture is passed through line 13 at a

which is possibly formed in statu nascendi, subtracted temperature below 427 ° C and consists of

is due. The reaction mixture in line 9 is a crude, flammable gas, the hydrogen,

therefore contains considerable amounts of water vapor, carbon monoxide, ethylene, methane, carbon dioxide

Contains nitrogen, hydrogen, carbon dioxide, carbon monoxide, and nitrogen. This gas from line 13

unsaturated hydrocarbons (mostly ethylene), io can be used directly as a gaseous fuel in certain

Methane and possibly ethane. However, application forms must be used, but will

it can be expected that some of these compounds will preferably be processed further to remove all unsaturated ones

gen in a transitional or momentary stage hydrocarbons, such as. B. Ethylene, which is

available. Insofar as substances act under these processes and are therefore un-

conditions a stable equilibrium is reached, 15 are desired to saturate. In addition, it is generally

finds noticeable formation and increased deposits think it is desirable to convert the gas flow,

of free carbon instead. whereby carbon monoxide by reaction with water

The temperature in the chamber 8 in which steam is converted into carbon dioxide can be in the range of 788 to 816 ° C. With so the hydrogen content of the gas is increased. Carbon-low reaction temperatures can, however, easily 20 dioxide is usually also the formation of free carbon, especially removed from the gas, in order to increase the calorific value by reducing the amount of ballast or inert gases, if all the remaining free oxygen is lost, is needed, if not the residence time in the size- Through line 13, the gas mixture is kept in the order of 0.05 to 0.33 seconds. Converter 14 passed, if necessary together with In general, the residence time in chamber 8 must 25 additional steam, which if necessary over 15 is added below 1.0 and preferably in the range from 0.05 to leads. Converter 14 is equipped with at least a 0.33 second hold to effect the desired catalyst bed 16, which usually consists of reactions without carbon formation. active iron oxide plus alkali oxide as a promoter must also be the instantaneous mixing temperature, which is applied to a suitable support. of the mixture in line 7 maintained above 538 ° C. The converter 14 can be derived from that disclosed in the U.S. patent since the various devices described in reference 3,010,807 have been found to consist of competing reactions to form free other suitable devices . If carbon tends to occur when the initial mixing causes the gas to flow through the converter 14, the temperature is below 538 ^° C. This initial or contact with the catalyst bed 16, the water gas instantaneous mixing temperature, should preferably be a shift reaction between carbon monoxide and in the range from 760 to 927 ° C in order to produce carbon formation caused by evaporation of water vapor, carbon dioxide and hydrogen. The converted gas, which through line 17 close. It is obvious that the chamber 8 is removed, has a low or negligible content of carbon monoxide, which is actually barren with regard to the construction of the device, and a relatively high content of free hydrogen, which consists of only an insulated piece of pipe.
The converted gas is fed through line 17 of a stream up to the entry of the gasified process- catalytic hydrogenation unit 18, which extends with stream into the following quenching stage. Wire mesh layers 19 is provided, which consists of a

In summary, it can be said that the platinum group metal, such as. B. platinum or palla competing reactions of heavy petroleum 45 exist. Optionally, unit 18 can also be provided with combustion, cracking and non-catalytic thermal a catalyst bed which consists of platinum shear steam reforming in the first stage of the process according to the invention applied to a suitable support. is. In 18 the catalytic hydrogenation of un-It has been found that these competing saturated compounds are in the gas.
Reactions without accumulation of carbon 50 The hydrogenated gas passes through line 20 in the can be carried out when the reaction scrubber 21, where the gas with a liquid scrubbing medium within certain critical limits, such as. B. hot aqueous potassium carbonate are held. In addition, the in-solution or aqueous monoethanolamine solution obtained is washed to stabilize the reaction product from the chamber 8, removing carbon dioxide. This is done if, before further reaction takes place, the scrubber 21 is fed with a packed section 22 for subsequent quenching, with gas-liquid contact being provided, optionally a crude, flammable gas mixture without carbon - for this purpose also fractionating bottom bells or accumulation is formed. It has been found that grid floors are used
the gas mixture obtained from the chamber 8 with The liquid washing solution is fed via line 23 to obtain success 60 as a stable, crude, flammable gas, and the absorbed carbon dioxide can be evacuated if it is released via line 24 before the final holding liquid solution is reached. Procedural equilibrium is deterred. removed to be regenerated outside the system.

The reaction gas mixture from chamber 8 reaches the end gas with a reduced carbon dioxide content through line 9 into the quenching unit 10, in which is removed from the unit 21 via line 25 and the gas mixture to a temperature below 427 ° C can then be cooled or otherwise quenched is, so that the reaction is not listed here before reaching the removal of the steam final equilibrium and the th methods are dealt with. That way will Carbon formation is prevented. A finished town gas produced through line 11, which mainly

Contains ethane, methane, hydrogen and nitrogen. Nitrogen is a desirable one in the finished town gas Component because it serves as ballast to dilute the gas flow in order to ensure the appropriate calorific value. Because of the hydrogenation in unit 18, the finished town gas only has a low unsaturated content Compounds that are undesirable because these compounds are considered during combustion Luminous substances have an effect and also show a tendency to smear.

In an optional embodiment of the method according to the invention, the chamber 8 can with a suitable catalyst, such as. B. metallic nickel rings, are equipped to prevent the formation of Hydrogen by catalytic steam reforming explained in more detail for 15 processes, promote, whereby an end gas product with a higher calorific value is obtained.

It has been found that the use of pressure is not an essential variant in the invention Procedure seems to be. Although the pressure is not critical, a working pressure is in the range of 1 to 22 at preferable, because then the size of the reformer installation and the costs for subsequent compression can be reduced. In addition, when the pressure is increased, the gasification leads to a High-pressure process gas, which is used to remove the carbon dioxide directly with hot potassium carbonate scrubbing solution can be treated.

For those skilled in the art it is obvious that the sufficient steam for a complete reaction with the heavy fuel is available. However, it has been found that a steam to carbon ratio in Range of 3 to 6 is optimal for complete reaction, and satisfactory reaction rate to ensure a minimal tendency towards carbon formation, which can be caused by process disturbances. When minimum steam to carbon ratios are used, these are generally ίο higher proportions of process air required to reduce the Avoid deposition of carbon. In general, the molar ratio of air moves towards Carbon between 0.1 and 1.0. In the following example, the invention

example

Production of a crude combustible gas Table I.

20 steam to carbon ratio

Air to carbon ratio

Response time, seconds.

essential process variants in the gasification 30 VerÜtemperätür '' ⁰ C of heavy benzine after the inventive inlet

drive are closely related to each other. So outlet

depends e.g. B. the required minimum preheating temperature outlet gas analysis

temperature of the reaction components before entry into '

chamber 8 mainly depends on the residence time in 8 before the reaction gas mixture passes through line 9 enters the quenching unit 10. It has been found that with low residence times of the order of magnitude from 0.05 to 0.10 seconds the process succeeds with a residence chamber temperature in the range of 788 to 816 ° C can be carried out. However, if longer dwell times up to 1.0 second are required the starting components 3, 4 and 5 must be preheated to a higher level in order to be able to move into chamber 8 Volume percentage (dry basis)

Carbon dioxide

Carbon monoxide

Ethylene

methane

hydrogen

nitrogen

Approach no 1 ² 3.6 4.4 0.58 0.59 0.48 0.37 16.9 10.5 927 927 816 807 9.9 11.0 8.5 7.4 5.8 7.8 20.5 16.6 27.8 27.6 27.5 29.6

927 816

9.6 12.5

7.2 16.0 31.1 23.6

Batches 1 and 2 were carried out non-catalytically, while batch 3 was carried out in the gasification step a nickel type catalyst was used. It

a higher temperature range of 899 to 921 ° C 45 it can be seen that in the exit gas of batch 3 a ensure that the increased deposit of higher content of free hydrogen is present, so that according to

free carbon is prevented according to the implementation of the method according to the invention.

It has also been found that, in general, a steam to carbon ratio of at least 1.5 is necessary to meet the requirements placed on the equilibrium of the reagents to ensure by making sure that the calorific value is also somewhat due to the catalytic effect is increased.

The following table shows the conversion of raw combustible gas from batch 3 to finished City gas explained. This conversion was carried out in accordance with those described above, various Process steps carried out.

Production of finished town gas Table II

Gas component Raw
flammable gas After this
Carbon monoxide
converter After
Hydrogenation plant After this
Carbon dioxide
washer Finished
Town gas
Volume percentage Carbon dioxide
Carbon monoxide
Ethylene 9.6
12.5
7.2
16.0
31.1
23.6 22.1
7.2
16.0
43.5
23.6 22.1
7.2
16.0
36.3
23.6 7.2
16.0
36.3
23.6 Ethane 8.6
19.3
43.7
28.4 methane hydrogen nitrogen

The finished town gas product had a net calorific value of 3889 kcal / m ³ and a specific weight of 0.502.

The following table shows the analytical values of the commercially available one used in the above approaches Heavy fuel (naphtha) indicated. It can be seen that heavy gasoline of various compositions and analytical values through a suitable choice of the process variants within the scope of the invention can be successfully reformed.

Table III

Characteristics of the heavy fuel examined
(Naphtha)

Initial boiling point 49 ° C

Final boiling point 121 ⁰ C

Specific weight at 15.6 ⁰ C 0.70

Composition (weight percent)

Paraffins 57.4

Naphthenes 32.5

Aromatics 9.4

Olefins 0.7

Sulfur content (ppm) 5 to 10

From the analysis values of the gas in Table I above, certain conclusions can be drawn about the likely reaction mechanism to be drawn. Since there is no oxygen, the combustion must take place of heavy gasoline (naphtha) must have already been carried out in full. As next to some unsaturated Compounds also methane is present, it is obvious that partial thermal cracking of the Heavy gasoline (naphtha) presumably together with partial hydrogenation of unstable free radicals and unsaturated carbon bonds have taken place. So this thermal cracking occurred without accumulation of carbon. Finally, there is also some free hydrogen available, which is why there is also a non-catalytic (thermal) steam reforming of heavy gasoline (naphtha) must have taken place.

Claims (3)

Patent claims: 1. A method for producing a carbon dioxide, carbon monoxide, ethylene, methane, hydrogen and nitrogen-containing fuel gas by steam reforming a hydrocarbon with preheating of evaporated hydrocarbon, steam and air and reforming the gas mixture, in particular on a reforming catalyst, characterized in that a temperature below 538 ⁰ C preheated heavy gasoline (naphtha) with superheated steam and preheated air at a temperature of at least 538 ⁰ C to a gas mixture with a molar ratio of steam to carbon of 1.5 to 6.0 and of air to carbon of 0.1 to 1.0 is mixed, this gas mixture is partially reacted for a period of less than 1.0 second while increasing the temperature to at least 76O ⁰ C and then the product obtained is quenched with a liquid coolant to a temperature below 427 ⁰ C and that optionally the raw gas mixture obtained under Zusa tz of water, converted from activated iron oxide on a catalyst, then catalytically hydrogenated and the finished gas mixture is washed with a liquid absorbent. 2. The method according to claim 1, characterized in that a nickel catalyst is used as the catalyst is used. 3. The method according to claim 1 and 2, characterized in that the liquid coolant is water is used. Considered publications:
German Auslegeschriften Nos. 1 003 910, 1 003 911, 035 309; German Auslegeschrift D 14766 IVa / 12i (published on 9/22/1955); Belgian Patent No. 501,930;
French Patent No. 1,019,972;
British Patent Nos. 680 874, 923 385;
U.S. Patent Nos. 2,371,147, 2,711,419. 1 sheet of drawings 809 588/189 7.68 ® Bundesdruckerei Berlin