PROCESS FOR PARTIAL OXIDATION OF A HYDROCARBON-CONTAINING GASEOUS FUEL

Abstract: Process for the partial oxidation of fuel using a multi-­ orifice burner comprising a central channel and three concentric channels encircling the central channel. Fuel is supplied through the first and third concentric channel and the oxidizer is supplied through the central channel and the second concentric channel. The supply occurs at specific mass flow distribution and velocities.

Description: The invention relates to a process for partial oxidation of a hydrocarbon-containing gaseous fuel using a multi-orifice burner. In particular, the invention relates to a process for partial oxidation of a hydrocarbon-containing gaseous fuel wherein an oxygen-containing gas and a hydrocarbon-containing gaseous fuel are supplied to a gasification zone through a multi-orifice burner comprising a concentric arrangement of 2 oxygen-passages or channels and 2 fuel passages or channels, and wherein autothermically a gaseous stream containing synthesis gas is produced under partial oxidation 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 can be supplied to said zone. More in particular, the invention relates to a process as described in the foregoing, wherein a gas such as natural gas, refinery gas, methane and the like is suitable as a fuel gas. In such processes it is necessary to ensure a good and rapid contacting or mixing of the fuel and the oxygen-containing gas in order to obtain an excellent gasification process. Further, in such process the lifetime of the equipment can be elongated by the reduction of the convective and radiative heat-flux via flame-lift without distorting the process performance. It is an object of the invention to provide a process for partial oxidation of a hydrocarbon-containing gaseous fuel wherein a rapid and intimate mixing of the reactants outside the concentric arrangement is obtained. It is another object of the invention to provide a process for partial oxidation of a hydrocarbon-containing gaseous fuel wherein the mixing energy of oxygen and fuel is provided by the high velocity fuel flow. It is another object of the invention to provide a process for partial oxidation of a hydrocarbon-containing gaseous fuel wherein pressure losses are minimized and wherein shorter reactor lengths are made possible, since the effective reactor residence time is maintained via the reduction of the effective burner velocity and the mixing distance downstream the burnerface. It is still another object of the invention to provide a process for partial oxidation of a hydrocarbon-containing gaseous fuel wherein highly exothermic reactions are prevented in the region where the relatively hot syngas from the reactor mixes with the reactants from the third concentric channel. The invention therefore provides a process for partial oxidation of a hydrocarbon-containing gaseous fuel comprising the steps of supplying an oxygen-containing gas and a hydrocarbon-containing gaseous fuel to a gasification zone through a multiorifice reactor-mix burner comprising a concentric arrangement of 2 oxygen passages or channels and 2 fuel passages or channels, and producing auto-thermically a gaseous stream containing synthesis gas under partial oxidation conditions, and further comprising the steps of supplying oxygen-containing gas through the central channel of the concentric arrangement at a relatively low velocity of 5-45 m/s; supplying hydrocarbon-containing gaseous fuel through the first concentric channel encircling the central channel at a relatively high velocity of 50-150 m/s; supplying oxygen-containing gas through the second concentric channel encircling the first channel at a relatively low velocity of 5-45 m/s; and supplying hydrocarbon-containing gaseous fuel and/or a moderator for controlling the temperature in the gasification zone through the third concentric channel encircling the second channel at a relatively low velocity of 5-45 m/s, and wherein the respective velocities are measured at the outlet of the said respective concentric channels into the gasification zone. It can be remarked that EP-A-98043 discloses a premix burner to be used in coal gasification. This burner comprises four coaxial conduits. Further, US-A-4,525,175 discloses a burner for partial oxidation of slurries of solid fuel wherein the burner has a central conduit and three concentric annular passages. However, these citations do not disclose at all the specific process and process conditions for partial oxidation of a hydrocarbon-containing gaseous fuel. In advantageous embodiments of the invention 30 to 45 mass per cent of the oxygen-containing gas is supplied through the said central channel and 10 to 20 mass per cent of the fuel is supplied through the third concentric channel. The velocity measurement can be carried out in any way suitable for the purpose and will not be described in detail. In still another advantageous embodiment of the invention the oxygen-containing gas and/or the fuel contain steam or carbon dioxide as a moderator. In still another advantageous embodiment of the invention the gasification process is carried out at a pressure of 0.1-12 MPa. In still another advantageous embodiment of the invention the hydrocarbon containing fuel is a gas, for example methane, natural gas or refinery gas. The fuel and the oxygen-containing gas are supplied to the gasification zone through a concentric arrangement of 2 oxygen passages and 2 fuel passages. A central channel for oxygen (advantageously mixed with a moderator) supply is surrounded by a first annular channel for fuel supply. The said first annular channel is surrounded by a second annular channel for oxygen (advantageously mixed with a moderator) supply and the said second channel is surrounded by a third annular channel for fuel and/or moderator supply. Multi-orifice burners comprising arrangements of annular concentric channels for supplying oxygen and fuel to gasification zones are known as such and the mechanical details thereof will not be described. According to the invention the oxygen and the fuel are supplied to the gasification zone through the respective channels at specific low velocities and specific mass distribution in order to obtain low pressure loss, rapid and intimate mixing of reactants, effective long reactor residence time and flame lift. The invention will now be described in more detail by reference to the following examples. Tests have been carried out under the following conditions:

Claims: A process for partial oxidation of a hydrocarbon-containing gaseous fuel comprising the steps of supplying an oxygen-containing gas and a hydrocarbon-containing gaseous fuel to a gasification zone through a multi-orifice reactor-mix burner comprising a concentric arrangement of 2 oxygen passages or channels and 2 fuel passages or channels, and producing auto-thermically a gaseous stream containing synthesis gas under partial oxidation conditions, and further comprising the steps of supplying oxygen-containing gas through the central channel of the concentric arrangement at a relatively low velocity of 5-45 m/s; supplying hydrocarbon-containing gaseous fuel through the first concentric channel encircling the central channel at a relatively high velocity of 50-150 m/s; supplying oxygen-containing gas through the second concentric channel encircling the first channel at a relatively low velocity of 5-45 m/s; and supplying hydrocarbon-containing gaseous fuel and/or a moderator for controlling the temperature in the gasification zone through the third concentric channel encircling the second channel at a relatively low velocity of 5-45 m/s, and wherein 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 characterized in that the oxygen-containing gas and/or the fuel is mixed with a moderator. The process as claimed in claim 1 characterized in that the moderator is steam or carbon dioxide. The process as claimed in any one of 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 30-45 mass per cent of the oxygen-containing gas is supplied through the said central channel. The process as claimed in any one of claims 1-5 characterized in that 10-20 mass per cent of the fuel is supplied through the said third concentric channel. The process as claimed in any one of claims 1-6 characterized in that said hydrocarbon-containing fuel gas is natural gas or refinery gas. The process as claimed in claim 7 characterized in that said fuel gas is methane.

Inventors: MARTENS, FRANCISCUS JOHANNA ARNOLDUS
Applicants: SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V.
Application year: 1988
Main classification: C01B3
IPC codes: F23D14, C01B3, F23D99