Process for partial oxidation of a liquid or solid and/or a gaseous hydrocarbon-containing fuel

Abstract: Process for the partial oxidation of a liquid or solid and/or a gaseous fuel using a multi-orifice burner comprising a central channel and four concentric channels encircling the central channel. Liquid or solid fuel is supplied through the second concentric channel and the oxidizer is supplied through the first concentric channel and the third concentric channel. Hydrocarbon gas and/or moderator is supplied through the central channel and the fourth concentric channel. The supplies occur at specific mass flow distributions and velocities. The mass ratio of liquid or solid fuel to hydrocarbon gas ranges from 0 to 1.

Description: The invention relates to a process for partial oxidation of a liquid or solid and/or a gaseous hydrocarbon-containing fuel using a multi-orifice burner. In particular, the invention relates to a process for partial oxidation of a liquid or solid and/or a gaseous hydrocarbon-containing fuel wherein an oxygen-containing gas, a liquid or solid hydrocarbon-containing fuel and/or a hydrocarbon gas are supplied to a gasification zone through a multi-orifice burner comprising a concentric arrangement of 4 annular passages or channels and 1 central passage or channel, and wherein autothermically a gaseous stream containing synthesis gas is produced under appropriate conditions. The oxygen-containing gas is usually air or pure oxygen or a mixture thereof. In order to control the temperature in the gasification zone a moderator gas (for example steam or carbon dioxide) can be supplied to said zone. Synthesis gas is a gas comprising carbon monoxide and hydrogen, and it is used, for example, as a clean medium-calorificvalue fuel gas or as a feedstock for the synthesis of methanol, ammonia or hydrocarbons, which synthesis yields gaseous hydrocarbons and liquid hydrocarbons such as gasoline, middle distillates, lub oils and waxes. In the specification and in the claims the terms gaseous hydrocarbons and liquid hydrocarbons will be used to refer to hydrocarbons that are at gasifier feed pressure and temperature gaseous and liquid, respectively. A known method for producing synthesis gas is partially oxidizing a particulate solid fuel, such as coal, charcoal or petroleum coke, at a temperature in the range of from 1000 o C to 1800 o C and at a pressure in the range of from 0.1 MPa to 5 MPa in a reactor vessel with the use of an oxygen containing gas, wherein the particulate solid fuel is introduced into the reactor vessel in the form of a dispersion of particulate solid fuel in a gas such as an inert gas or syngas, or in the form of a dispersion of particulate solid fuel in a liquid such as residual oil or water. In addition thereto, synthesis gas can be produced by partially oxidizing a liquid fuel, such as alcohol or a liquid hydrocarbon, in particular residual oil. The liquid fuel is partially oxidized at a temperature in the range of from 1000 o C to 1800 o C and at a pressure in the range of from 0.1 MPa to 8 MPa in a reactor vessel with the use of an oxygen containing gas, wherein the flow of liquid fuel into the reactor vessel is disintegrated with the use of oxygen containing gas. Furthermore, synthesis gas can be produced by partially oxidizing in a reactor vessel a gaseous fuel such as gaseous hydrocarbons, in particular petroleum gas or natural gas, at a temperature in the range of from 1000 o C to 1800 o C and at a pressure in the range of from 0.1 MPa to 6 MPa with the use of an oxygen containing gas. In the specification and in the claims the term oxygen containing gas will be used to refer to air, steam or oxygen, and the term residual oil will be used to refer to a residual product that remains after application of a separation method such as, distillation or extraction on, for example, crude oil, tar sand, shale oil or coal extracts. Synthesis gas will be produced near or at a crude oil refinery because the produced synthesis gas can directly be applied as a feedstock for the production of middle distillates, ammonia, methanol or as a fuel gas, for example, for heating the furnaces of the refinery or more efficiently for the firing of gas turbines to produce electricity and heat. Moreover, use can be made of the waste products of the refinery. If synthesis gas is produced by partially oxidizing a gaseous fuel, use can be made of refinery gas or of the gaseous hydrocarbons produced as a by-product of a synthesizing process. If synthesis gas is produced by partially oxidizing a liquid fuel, use can be made of residual oil and oxidizer in order to disintegrate the flow of residual oil into the reactor vessel. If synthesis gas is produced by partially oxidizing a particulate solid fuel use can be made of particulate carbonaceous material dispersed in gas, in residual oil or water. However, in order to obtain a pumpable slurry a limited amount of particulate carbonaceous material can only be mixed with the liquid. The above methods for producing synthesis gas, however, do not offer a large amount of operating flexibility because, in order to obtain a pumpable slurry, only a limited amount of particulate carbonaceous material can be dispersed in the liquid. Further the H₂/CO ratio of the syngas can only be slightly varied without varying the amount of moderator gas. Further, it is already known to produce synthesis gas by introducing into a reactor vessel separated from each other at least two different fuels from the group which comprises particulate solid fuel, liquid fuel and gaseous fuel, and allowing the fuels to oxidize partially inside the reactor vessel with the use of an oxygen containing gas. In particular, the invention relates to a simultaneous gasification process as described in the foregoing, wherein (heavy) residue feedstock and a hydrocarbon gas (e.g. methane) are suitable to be used as fuels and wherein the liquid (or solid) and/or gaseous hydrocarbons can be supplied in any ratio. In such a process less moderator and oxidizer is required to achieve a specific H₂/CO ratio in the syngas. In order to obtain an excellent gasification process it is necessary to ensure fine atomization of the liquid and good and rapid contacting or mixing of the fuels oxygen-containing gas and the moderator. It is an object of the invention to provide a process for partial oxidation of a liquid or solid and/or a gaseous hydrocarbon-containing fuel wherein in situ fine atomization of the liquid is obtained or rapid dispersion of the solid. It is another object of the invention to provide a process for partial oxidation of a liquid or solid and/or a gaseous hydrocarbon-containing fuel wherein a good and rapid mixing or contacting of oxygen, fuels and moderator is obtained and pre-ignition or flame-flash-back is prevented. It is another object of the invention to provide a process for gasification wherein economic process conditions (for example reduction of supply moderator gas and reduction of carbon and soot production) are achieved with a sufficiently long burner-lifetime. The invention therefore provides a process for partial oxidation of a liquid or solid and/or a gaseous hydrocarbon-containing fuel characterized by the steps of supplying an oxygen-containing gas and hydrocarbon-containing fuel to a gasification zone through a concentric burner-arrangement of 4 concentric annular passages or channels and 1 central passage or channel, and producing auto-thermically a gaseous stream containing synthesis gas under appropriate conditions, and further comprising the steps of supplying the oxygen-containing gas through the first and third channels of the concentric arrangement at a relatively high velocity of 50-150 m/sec; supplying hydrocarbon-containing gas and/or a moderator through the central channel and the fourth concentric channel encircling the central channel at a medium velocity of 5-84 m/sec; supplying liquid or solid hydrocarbon-containing fuel through the second concentric channel encircling the first concentric channel at a relatively low velocity of 0-15 m/sec. Preferably the respective velocities are measured at the outlet of the said respective concentric channels into the gasification zone. The velocity measurement can be carried out in any way suitable for the purpose and will not be described in detail. It is remarked that EP-A-0,255,748 discloses a process for partial oxidation of a hydrocarbon-containing fuel applying a quadruple orifice burner having 3 oxygen-channels and 1 fuel-channel. Fuel is supplied through the second channel at a specific velocity; oxygen is supplied through the other channels at specific mass flow distribution and velocities. In another advantageous embodiment of the invention the moderator is steam or carbon dioxide. In still another advantageous embodiment of the invention the gasification process is carried out at a pressure of 0.1-12 MPa. Multi-orifice burners comprising arrangements of annular concentric channels for supplying oxygen, fuel and moderator to gasification zones are known as such and will not be described in detail. Usually such burners comprise hollow wall members with internal cooling fluid passages. However, the burner may for example be provided with a suitable ceramic or refractory lining applied onto or suspended by a means closely adjacent to the outer surface of the burner front wall for resisting the heat load during operation or heat-up/shut down situations of the burner. According to the invention the oxygen and the fuel are supplied to the gasification zone through the respective channels at specific velocities in order to obtain a good atomization and mixing. The invention will now be described in more detail by reference to the following examples. Examples Tests have been carried out under the following conditions: burner specification diameter central channel 52 mm slot width first co-annular channel 4.3 mm second 3.0 mm third 3.5 mm fourth 5.7 mm specification residual feedstock as fed to the burner C/H ratio 1.41 mol/mol density 1000 kg/m³ visosity 0.1 kg/(m.s) surface tension 0.03 kg/s² specification hydrocarbon containing gas as fed to the burner composition 50 v% CH₄ 50 v% C₂H₆ temperature 250 o C specification oxidizer as fed to the burner composition 99 v% O₂ 1 v% N₂ + Ar temperature 250 o C specification moderator as fed to the burner composition 100 v% steam temperature 250 o C It will be appreciated that in an advantageous embodiment of the present invention soot or other carbonaceous material can be transported to the gasification zone by the fuel gas stream. Alternatively, the co-annular channels of the multi-orifice burner can advantageously be used for the feeding of a (concentrated) water/soot slurry ex a gasification process or of another waste stream like spent solvents with or without addition of poisonous materials such as dioxine, which otherwise may be very difficult to decompose. Various modifications of the present invention will become apparent to those skilled in the art from the foregoing description. Such modifications are intended to fall within the scope of the appended claims.

Claims: A process for partial oxidation of a liquid or solid and/or a gaseous hydrocarbon-containing fuel comprising the steps of supplying an oxygen-containing gas and hydrocarbon-containing fuel to a gasification zone through a concentric burner-arrangement of 4 concentric annular passages or channels and 1 central passage or channel, and producing auto-thermically a gaseous stream containing synthesis gas under appropriate conditions, and further comprising the steps of supplying the oxygen-containing gas through the first and third channels of the concentric arrangement at a relatively high velocity of 50-150 m/sec; supplying hydrocarbon-containing gas and/or a moderator through the central channel and the fourth concentric channel encircling the central channel at a medium velocity of 5-84 m/sec; supplying liquid or solid hydrocarbon-containing fuel through the second concentric channel encircling the first concentric channel at a relatively low velocity of 0-15 m/sec. The process as claimed in claim 1 characterized in that the respective velocities are measured at the outlet of the said respective concentric channels into the gasification zone. The process as claimed in claim 1 or 2 characterized in that the moderator is steam or carbon dioxide. The process as claimed in claims 1-3 characterized in that the process is carried out at a pressure of 0.1-12 MPa. The process as claimed in any one of claims 1-4 characterized in that 50 ± 30 mass per cent of the total mass flow of the oxygen-containing gas is supplied through the said first concentric channel, whereas the remaining mass flow is supplied to the said third concentric channel. The process as claimed in any one of claims 1-5 characterized in that 60 ± 30 mass per cent of the total mass flow of the hydrocarbon containing gas and/or moderator is supplied through the central channel, whereas the remaining mass flow is supplied to the said fourth channel.

Inventors: MARTENS FRANCISCUS JOHANNA ARN, MARTENS, FRANCISCUS JOHANNA ARNOLDUS
Applicants: SHELL INT RESEARCH, SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V.
Application year: 1989
Main classification: C01B3
IPC codes: C01B3, C10L3, C10G9, C10L1, C10J3