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INVENTION
Russian Federation Patent RU2266946
METHOD FOR GAS, hydrogen-rich AND / OR CARBON MONOXIDE
Name of the inventor: PRIMDAL Ivars Ivars (DK); CHRISTENSEN, Thomas Sandal (DK)
The name of the patentee: Haldor TOPSEE A / S (DK)
Address for correspondence: 103064, Moscow, ul. Kazakova, 16, NIIR Office "Patent attorneys Kvashnin, Sapelnikov and partners", V.P.Kvashninu
Starting date of the patent: 2001.01.10
The invention relates to the production of gas rich in hydrogen and / or carbon monoxide. The process is carried out in a reactor having a top and bottom, comprising the steps of introducing heated to 400-700 ° C hydrocarbon feed into the top of the reactor, mixing the raw material with steam and oxygen containing atmosphere, its partial oxidation with oxygen in the upper part of the reactor and, if necessary, contacting the partially oxidized feedstock from the upper portion of the reactor with the catalyst the steam reforming placed at the bottom of the reactor, with part of the partially oxidized feedstock is contacted with a catalyst active in hydrocarbon steam reforming, placed at least on the surface of the upper part reactor. Mixing of raw material with steam and oxygen containing atmosphere is performed in an amount to provide a molar ratio of oxygen / carbon ratio in the treated gas between 0.5-0.7 and the molar ratio of steam / carbon is between 0.5-1.5. The method can significantly reduce the formation of soot in the combustion zone at critical process conditions.
DESCRIPTION OF THE INVENTION
The present invention relates to the technology of production of hydrogen and carbon-containing gases, in particular to a method for producing a hydrogen-rich and / or carbon monoxide gas by catalytic autothermal reforming of hydrocarbons.
The gases enriched with carbon monoxide and hydrogen is mainly used as synthesis gas in the production of ammonia and methanol or other organic compounds.
These gases and find application in the production of steel and as a fuel gas and consumer.
Industrial preparation methods generally comprise autothermal catalytic reforming and non-catalytic partial oxidation of hydrocarbons. At partial oxidation of a hydrocarbon feedstock is burned with air, oxygen or oxygen-enriched air in a burner mounted at the top of the reactor. Oxygen is thus supplied in amounts which are less than the amount required for complete combustion, to obtain hydrogen and carbon monoxide in the exhaust gas mainly in the combustion reaction flame
Both reactions are all strongly exothermic hydrocarbon.
Partial oxidation is typically employed in the gasification of heavy oils, where the temperature of the gas increases during the combustion to 1000-1500 ° C which is high enough to give a sufficiently low content of unconverted hydrocarbons in the gas discharged after the burning process. The lighter feedstock ranging from natural gas to naphtha with boiling points up to 200 °, is usually treated with a catalytic autothermal reformer feed.
During this process, only part of the hydrocarbon feedstock is oxidized with an oxygen-containing atmosphere by the above flame reactions (1, 2). Residual hydrocarbons in the gas stream after combustion are then catalytically steam reformed by the endothermic reaction,
Necessary heat for the endothermic steam reforming with the exothermic reactions to deliver flame (1, 2).
Somewhat lower combustion temperatures are used during autothermal catalytic reforming, which is usually carried out at a temperature of about 900-1400 ° C. To add steam feed to reduce the flame temperature and increase hydrocarbon conversion in the gas leaving the burner.
Similarly, the partial oxidation process, hydrocarbon feed mixed with steam is burnt in an oxygen-containing atmosphere at the top of the reactor. Residual hydrocarbons in the gas, which is the product of combustion is subjected to steam reforming in the presence of a catalyst arranged as a fixed bed in the reactor bottom. Heat for the endothermic reforming reactions with steam fed by hot gas leaving the combustion zone in the upper reactor portion and above the catalyst bed. When gaseous combustion products come into contact with the catalyst, the gas temperature is reduced to 900-1100 ° C by the reforming reactions with steam within the catalyst bed.
In carrying out the above processes, suitable hydrocarbon feed, if necessary after preheating is supplied to the burner disposed in the upper part of the reactor and burnt with oxygen containing atmosphere. To protect the reactor shell against the high temperatures arising during the exothermic oxidation reactions, industrial reactors are provided with a temperature-resistant refractory insulating lining on the inner wall of the pressure reactor vessel.
lining materials must be able to withstand the high temperatures and be resistant to the damaging effects of the hot gases. Currently refractory materials are commonly used in industrial reactors of the above types contain more than 90% alumina.
The closest to the invention is a method for producing a gas rich in hydrogen and / or carbon monoxide in the reactor having a top and bottom, comprising the steps of introducing heated to 400-700 ° C hydrocarbon feed into the top of the reactor, mixing it with steam and oxygen containing atmosphere partial oxidation of the feedstock with oxygen in the upper part of the reactor and, if necessary, contacting the partially oxidized feedstock from the upper portion of the reactor with the catalyst the steam reforming placed at the bottom of the reactor. Reactor for implementing the method comprises a pressure housing, a refractory lining on the inner wall of the pressure housing, an upper portion adapted to receive a hydrocarbon feedstock and an oxygen-containing atmosphere, and partial oxidation with oxygen feed and a lower part which can be fitted with reforming catalyst for steam reforming partially oxidized gas discharged from the top (see. EP A2 №0583211 C 01 B 3/36, 1994).
The main problem in the production of synthesis gas is the formation of soot in the combustion zone at critical process conditions, such as low ratio of steam to carbon in the feedstock fed to processing.
The object of the invention is to prevent or at least substantial reduction in the formation of soot in the combustion zone at critical process conditions.
The problem is solved by the proposed method produce a gas rich in hydrogen and / or carbon monoxide in the reactor having a top and bottom, comprising the steps of introducing heated to 400-700 ° C hydrocarbon feed into the top of the reactor, mixing it with steam and oxygen containing atmosphere partial oxidation of the oxygen feed at the top of the reactor and, if necessary, contacting the partially oxidized feedstock from the upper portion of the reactor with the catalyst the steam reforming placed at the bottom of the reactor, which is that portion of the partially oxidized feedstock is contacted with the catalyst active in hydrocarbon steam reforming, placed at least on the surface of the upper part of the reactor, mixing the feed with steam and an oxygen-containing atmosphere is carried out in an amount to provide a molar ratio of oxygen / carbon ratio in the treated gas between 0.5-0.7 and the molar ratio of steam / carbon is between 0.5-1.5.
According to a preferred feature of the present process the hydrocarbon feedstock and an oxygen-containing atmosphere may be mixed in a burner before introduction into the top of the reactor.
A theoretical explanation of the formation of a significant reduction in carbon black can consist in that the number of precursor molecules participating in the formation of soot, decreases, or they react in the reactions with steam reforming proceeding on the catalyst surface, adjacent to the combustion zone. Increased concentration of hydrogen in the process of steam reforming taking place in this region leads also to improved fire and oxygen mixture feed and the process beginning at less severe conditions.
Typical hydrocarbon feedstocks suited for the process, ranging from methane to naphtha with boiling points up to 200 ° C, including natural gas, liquefied petroleum gas and natural gas subjected to the primary reforming, the implementation of the process under autothermal catalytic reforming. The process gas fed from the burner into the combustion zone in the upper reactor portion, where part of the hydrocarbons in the gas reacts with oxygen to form carbon oxides and hydrogen in accordance with the combustion flame reactions (1) and (2) as described above.
Depending on the desired composition of the final product gas, oxygen may be supplied from air or oxygen enriched air as in the preparation of synthesis gas for ammonia production, or from oxygen for the production of gas for hydroformylation and reducing gas, where nitrogen is unwanted in the final product gas . During hydrocarbon oxidation the temperature in the combustion zone raises to 900-1500 ° C.
As a result of the endothermic steam reforming (3) proceeding in the gas on the surface adjacent to combustion zone, concentration of hydrogen in the recycled combusted gas is increased and content of soot precursor molecules decreased.
The actual increase of hydrogen concentration thus depends on the amount of hydrocarbons and steam in the gas from the combustion zone and the activity and amount of reforming catalyst in the upper portion of the reactor.
Catalysts suitable for this purpose include the well-known reforming catalysts of Group VIII of the Periodic Table, including nickel and / or cobalt, which for a significant reduction in soot formation and improve combustion is applied in amounts of between 0.1 g / m 2 and 1 g / m 2 on the facing surface of the conventional techniques of impregnation or coating.
When the process occurs in the autothermal catalytic reforming conditions, the gas exiting the combustion zone is further passed through a fixed bed of conventional nickel and / or cobalt reforming catalyst arranged in the lower part of the reactor. By passage through the catalyst bed, residual hydrocarbons in the gas are subjected to further steam reformed to hydrogen and carbon monoxide.
The proposed method can be carried out in a reactor, schematically represented in the attached drawing.
 | The figure shows that the reactor 1 consists of a pressure casing 2 containing a reforming catalyst layer 3. The reactor 1 is provided with a further inlet openings 4, 5 for feeding a feed gas source and an oxygen-containing medium, respectively, and an outlet 6 for discharging the reaction gas. Pressure shroud 2 is protected from the high temperatures encountered in the reactions in the gaseous reaction medium, the refractory lining 7 located on the inner wall of the discharge housing 2. Further, the reactor has a layer 8 deposited on the liner 7 reforming catalyst, at least one of its part which encases the upper part 9 of the reactor 1. |
The invention and its technical result is illustrated by the following examples.
example 1
In the upper part of the reactor shown in the drawing is introduced 100 Nm 3 / h of natural gas composition (mol.%) 94 55 CH 4, C 2 2.75 0.70 C 3, 0,31 C 4, 0,11 C 5+, 1.16 and CO 2 0,42 N 2, 2 nm 3 / h hydrogen and 55 Nm3 / h of steam. Oxidizer feed comprises 57 Nm 3 / h of oxygen, containing 0.50 mol.% Nitrogen, and a 6 Nm 3 / hr of steam. Thus, as the molar ratio of oxygen / carbon and a molar ratio of steam / carbon in the gas to be treated is 0.6. The hydrocarbon feedstock is preheated to a temperature of 500 ° C, and the oxidizing agent - up to 220 ° C. All the working gas pressure was adjusted to 2.46 MPa.
From the combustion chamber of the reactor is withdrawn gas specified in the following table structure.
Example 2 (comparison)
Example 1 was repeated with the difference that the process is carried out in the reactor at which the top of the liner is not a layer of reforming catalyst.
In this reactor the combustion chamber of the gas is withdrawn following composition table.
| Table | |||||||||
| Example number | The composition of the gas rich in hydrogen and carbon monoxide, mol.% | ||||||||
| H 2 | H 2 O | CO | CO 2 | CH 4 | C 2 H 6 | C 2 H 4 | C 2 H 2 | N 2 | |
| 1 | 45.01 | 23.37 | 21.43 | 4.21 | 5.69 | 0.06 | 0.04 | 0.02 | 0.21 |
| 2 | 42.96 | 23.61 | 21.56 | 3.99 | 7.36 | 0.01 | 0.15 | 0.14 | 0.21 |
| (comparison) | |||||||||
Comparison of the results of the above experiments demonstrates that the proposed method produced according to the gas has a substantially lower concentration of C 2 hydrocarbons (ethane, ethylene, and acetylene), which are the precursors of soot on that stated above.
CLAIM
1. A method for producing a gas rich in hydrogen and / or carbon monoxide in the reactor having a top and bottom, comprising the steps of introducing heated to 400-700 ° C hydrocarbon feed into the top of the reactor, mixing it with steam and oxygen containing atmosphere, partial oxidation by oxygen feed at the top of the reactor and, if necessary, contacting the partially oxidized feedstock from the upper portion of the reactor with the catalyst the steam reforming placed at the bottom of the reactor, wherein the portion of the partially oxidized feedstock is contacted with a catalyst active in reforming hydrocarbons with steam, disposed at least on the surface of the top of the reactor, mixing the feed with steam and an oxygen-containing atmosphere is carried out in an amount to provide a molar ratio of oxygen / carbon ratio in the treated gas between 0.5-0.7 and the molar ratio of water steam / carbon ratio between 0.5-1.5.
2. The method of claim 1, wherein the hydrocarbon feedstock and an oxygen-containing atmosphere is mixed in a burner before introduction into the top of the reactor.
print version
Publication date 02.03.2007gg
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