Refrigeration – Cryogenic treatment of gas or gas mixture – Separation of gas mixture
Reexamination Certificate
2000-05-10
2002-01-22
Capossela, Ronald (Department: 3744)
Refrigeration
Cryogenic treatment of gas or gas mixture
Separation of gas mixture
C062S240000, C062S901000, C062S939000
Reexamination Certificate
active
06339939
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a process and to a plant for the conversion of a flow containing hydrocarbons by partial oxidation.
BACKGROUND OF THE INVENTION
In this type of process, a flow containing hydrocarbons, typically natural gas, is converted into synthesis gas after partial oxidation with oxygen or oxygen-enriched air.
This conversion can be carried out by a reforming process, for example of the ATR (Autothermal Reforming) type, which mates it possible to produce a synthesis gas. Following catalytic conversion, the synthesis gas is converted into liquid hydrocarbons (kerosene, diesel, naphtha).
This type of process is described in U.S. Pat. No. 5,628,931, WO 93 15999, GB 2249555, GB 2183672, EP 214 432 A.
SUMMARY OF THE INVENTION
The present invention also relates to a process and to a plant for the separation of air by cryogenic distillation and, in particular, to those processes and plants which make it possible to produce oxygen.
According to one subject of the invention, a process is provided for the conversion of a flow containing hydrocarbons by partial oxidation with oxygen,
characterized in that the oxygen needed for the conversion is separated by cryogenic distillation from air in a single column installed on a boat.
According to other aspects of the invention,
the flow containing hydrocarbons is methane, natural gas or LPG,
the oxygen is drawn off from the single column in liquid form, pressurized and vaporized,
the conversion is carried out by a reforming process producing a synthesis gas, which reforming is followed by catalytic conversion of the synthesis gas into liquid hydrocarbons,
the nitrogen needed for the process is produced by adsorption or permeation.
According to another subject of the invention, a plant is provided for the conversion of a flow containing hydrocarbons, comprising a partial-oxidation unit fed with oxygen,
characterized in that it comprises air separation apparatus including a single column (
8
) installed on a boat.
Oxygen is generally produced by the distillation of air in a double column. When this column is placed on an unstable support, such as the deck of a boat, the quality of the distillation is degraded because the plates or packing contained in the column cannot function correctly.
“Nitrogen for Inerting” Tank and Bulk Carrier, November 1973 and “Distillation Problems on a Floating Plant” CEP, November 1982, describe solutions for improving distillation on a boat.
The object of this invention is to provide an air separation process which is compatible with the working conditions on a boat.
According to another subject of the invention, a process is provided for the separation of air by cryogenic distillation in a single column, in which
i) air to be distilled is sent into a single column where it is separated into a nitrogen-enriched vapour and an oxygen-enriched liquid,
ii) the base of the column is heated by means of a boiler,
characterized in that at least some of the oxygen-enriched liquid is drawn off, pressurized and vaporized by heat exchange with a pressurized flow.
According to other aspects of the invention, the fluid used to heat the boiler is nitrogen or at least some of the air to be distilled,
the air sent to the boiler comes from a turbine, optionally coupled to a booster,
the pressurized flow is air at a boosted pressure or compressed nitrogen,
vapour is drawn off from the head of the column and at least some of it is compressed,
at least some of the compressed nitrogen is recycled to the column,
oxygen-enriched liquid is produced,
at least some of the air intended for the column is cooled to an intermediate temperature in a heat exchanger, before being expanded, optionally to the column pressure, in a turbine.
According to another subject of the invention, a plant is provided for the separation of air by cryogenic distillation, comprising,
a single column,
means for feeding the single column with air,
a boiler at the base of the single column,
means for sending a heating fluid to the boiler,
characterized in that it comprises
means for drawing off an oxygen-enriched liquid from the base of the single column,
means for pressurizing at least some of the liquid,
means for vaporizing at least some of the pressurized liquid by heat exchange with a pressurized flow.
According to other aspects of the invention,
the boiler is heated with nitrogen or at least some of the air to be distilled,
the boiler is connected to a turbine,
the pressured flow is air at a boosted pressure or compressed nitrogen,
means are provided for compressing a nitrogen-enriched flow drawn off from the head of the column,
the single column contains plates or structured packing.
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Hakan V. Svensson, “Distillation Problems on a Floating Plant”, Chem. Eng. Prog., Nov. 1982, vol. 78, No. 11, pp. 43-46, XP002064388.
W.H. Aitken, “Nitrogen for Inerting”, Tanker & Bulk Carrier, Nov. 1973, pp. 9-15, XP002064389.
Capossela Ronald
L'Air Liquide
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