Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/22—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion
  • B01D53/229—Integrated processes (Diffusion and at least one other process, e.g. adsorption, absorption)
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen; Reversible storage of hydrogen
  • C01B3/50—Separation of hydrogen or hydrogen-containing gases from gaseous mixtures, e.g. purification
  • C01B3/501—Separation of hydrogen or hydrogen-containing gases from gaseous mixtures, e.g. purification by diffusion
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof
  • C01B32/40—Carbon monoxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/10—Single element gases other than halogens
  • B01D2257/108—Hydrogen
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/50—Carbon oxides
  • B01D2257/502—Carbon monoxide
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
  • C01B2203/0465—Composition of the impurity
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
  • C01B2203/0465—Composition of the impurity
  • C01B2203/047—Composition of the impurity the impurity being carbon monoxide
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
  • C01B2203/0465—Composition of the impurity
  • C01B2203/048—Composition of the impurity the impurity being an organic compound
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
  • C01B2203/0465—Composition of the impurity
  • C01B2203/0495—Composition of the impurity the impurity being water

Definitions

• the present invention relates to a process for the separation of a gas mixture by a membrane permeation unit, of the type in which the gas mixture comes from a reaction unit and comprises, as main constituents, essentially hydrogen and carbon monoxide. carbon.
• the consumption of gaseous mixture containing essentially hydrogen and carbon monoxide, as well as possibly water, carbon dioxide, methane, nitrogen and / or argon, is important in de many industries because such mixtures constitute synthesis gases used for various productions.
• gaseous mixtures generally come from one or more reaction media, themselves supplied by gaseous charging fluids.
• reaction media themselves supplied by gaseous charging fluids.
• units for steam reforming of liquid or gaseous hydrocarbons auto-thermal reforming, carbon dioxide reforming, reforming or cracking of methanol, or partial oxidation of gaseous, liquid or solid compounds containing carbon and hydrogen.
• permeation membrane units to separate a gaseous mixture of the aforementioned type into one or more production fluids is increasingly common, since these units are easy to implement and a relatively low initial investment for a return satisfactory separation.
• monitoring the performance of these units has shown that the separation qualities decrease over time, contrary to what was expected for gas mixtures of the aforementioned nature. This change in performance is reflected, as the case may be, by a reduction in the extraction yield, by a drop in purity or by a modification of the desired H 2 / CO ratio, phenomena all having a negative effect from the economic point of view.
• the object of the invention is to propose a method of the aforementioned type, which makes it possible to maintain the permeation performance of the membrane unit over time.
• the subject of the invention is a process of separation by permeation of the aforementioned type, in which, upstream of the membrane unit, the gas mixture is purified into secondary constituents contained in said mixture at contents substantially below 100 ppm molar and damaging by accumulation to the separation performance of the membrane unit.
• the contents of the secondary constituents contained in the gaseous mixture are less than 10 ppm molar, typically less than 1 ppm molar;
• the reaction unit comprises a steam reforming unit for hydrocarbons, the secondary constituents being, at least in part, produced by secondary reactions during the reforming of the hydrocarbons;
• the reaction unit comprises an auto-thermal reforming unit, the secondary constituents being, at least in part, produced by secondary reactions during auto-thermal reforming;
• the reaction unit comprises a carbon dioxide reforming unit, the secondary constituents being, at least in part, produced by secondary reactions during the reforming of carbon dioxide;
• the reaction unit comprises a methanol reforming or cracking unit, the secondary constituents being, at least in part, produced by secondary reactions during the reforming or cracking of methanol;
• the reaction unit comprises a partial oxidation unit of compounds containing carbon and hydrogen, the secondary constituents being, at least in part, produced by secondary reactions during the oxidation of said compounds;
• the secondary constituents comprise at least one of the following components: an acid of the carboxylic or inorganic type, an acid anhydride, chlorinated, cyclic and / or sulfur compounds, an alcohol and / or a ketone and / or a phenolic compound, ammonia and / or at least one amino radical, at least one carbonyl metal;
• the gas mixture is purified into said secondary constituents by adsorption of said constituents by passage through an adsorbent material or by washing the mixture with water, to retain and remove from said mixture said secondary constituents in aqueous solution.
• FIG. 1 is a schematic view of an installation according to the invention for separation of a gas mixture from a reforming installation
• FIG. 2 is a schematic view illustrating a first embodiment of a unit of the installation according to the invention of Figure 1;
• Figure 3 is a variant of the unit of Figure 2;
• FIG. 4 is a view illustrating a second embodiment of the unit of Figure 2.
• FIG. 5 is a view of a variant of the unit of Figure 4.
• FIG. 1 shows an installation 1 for producing a synthesis gas mixture and an installation 2 for separation by permeation of this synthesis gas mixture into a fraction enriched in carbon monoxide and in a stream having a high hydrogen content.
• the installation 1 essentially comprises a steam reforming unit 4 and a treatment unit 6 intended for removing the acid gases, in particular carbon dioxide C0.
• the unit 4 is adapted to produce, from a flow of hydrocarbon feedstock, via a feed pipe 8, and from a feedstock load of water vapor, via a feed pipe 10, both a premix rich in hydrogen and carbon monoxide, via an evacuation pipe 14, and an excess of water vapor, via an evacuation pipe 12, advantageously connected to the supply pipe 10 .
• this gaseous premix varies according to the nature of the charge at 8, according to the quantity of water vapor injected at 10 and according to the operating conditions in pressure and temperature of unit 4.
• the premix generally comprises as main constituents 60 to 70% by molar volume of hydrogen, 15 to 30% of carbon monoxide, 5 to 10% of carbon dioxide and 1 5% methane.
• the processing unit 6 is adapted to purify the premix of its acidic impurities, in particular carbon dioxide, by lowering their respective contents to values conforming to predetermined specifications, in particular to specifications required by installations of which it is envisaged. the downstream connection to the production facility 1.
• the installation 1 is provided with a production line 16 connected to the separation installation 2.
• the processing unit 6 comprises a column 6A for washing with solvents, the solvents being, for example, dimethyl ether, polyethylene glycol, an amino solution and / or methanol. Introduced at the head of the column via a line 6B, these solvents are capable of physically absorbing the major part of the acid impurities of the premix and, once loaded with these impurities, are drawn off in the column tank, via a line 6C, for example to be regenerated and then recycled.
• the installation 2 for separating the gas mixture essentially comprises a membrane separation unit 20 and, upstream of the latter, connected by a pipe 22, a purification unit 24.
• the membrane unit 20 comprises at least one membrane 20A, intended to separate the gas mixture by permeation into one or more production gas streams, for example, into a stream with predetermined H 2 / CO ratio or else into a stream with a high content carbon monoxide and a stream with a high hydrogen content.
• the unit 20 in FIG. 1 is provided with a membrane 20A with high hydrogen selectivity, adapted to produce a permeate with a high hydrogen content, via a line 20B, and a non-permeate with a content of high carbon monoxide, via a 20C line.
• such a membrane unit 20 can comprise, in addition to the membrane (s) 20A themselves disposed in a permeator, additional equipment such as condensate separators, filters, heat exchangers intended to heat the charge mixture, to cool the flows from the permeator, etc.
• the unit 24 is adapted for its part to purify the gaseous mixture into secondary constituents which this mixture contains in the form of traces, typically at levels less than 100 ppm molar and harmful by accumulation at the separation performance of the membrane unit 20.
• - metals-carbonyls such as those of iron or nickel
• - alcohols methanol, ethanol, etc. ;
• n-chlorobenzene for example
• a content of these constituents substantially equal to 100 parts per trillion, that is to say a content of approximately 10 -7 molar, of a gas mixture with a flow rate substantially equal to 10,000 Nm 3 / h generates, after six months of operation of the membrane unit 20, ten kilograms of potential deposit on the surface or in the volume of the membrane 20A, by accumulation.
• FIG. 2 is shown a first embodiment of the purification unit 24 according to the invention.
• the functional contours of the unit 24 are indicated by a dashed line.
• the unit 24 comprises a single bottle 30 (or, as a variant, several bottles in parallel) connected at the inlet to the branch 16B for supplying a gaseous mixture, and at the outlet at the pipe 22.
• This bottle contains an adsorbent material, such as than alumina, molecular sieve, silica gel, activated carbon, or a mixture of several of these materials.
• the adsorbent material contained in the bottle is doped, that is to say impregnated with an agent reinforcing its adsorption capacity.
• the material used can also stop certain secondary impurities by chemisorption.
• the material can be metallic in nature, for example a metallic oxide.
• the adsorption of an impurity can also be followed by its decomposition into a light constituent which is not aggressive for the membrane, for example CO, and a heavier constituent, for example a metal, which is deposited on the adsorbent material.
• adsorbent will be used to designate this material, whether the phenomenon involved is physisorption, chemisorption or a combination of the latter.
• the bottle 30 is thus able to retain by adsorption the constituents damaging by accumulation to the separation performance of the membrane unit 20.
• the gas mixture coming from the reforming installation 1 passes through the adsorbent material of the bottle 30, the latter fixing, at least in part, the aforementioned constituents.
• the bottle 30 is replaced by a new bottle, the saturated material possibly being regenerated by suitable known means.
• the unit 6 comprises, in addition to the first bottle 30, a second bottle 32 connected in series to the first by a connection pipe 34, as shown in FIG. 3.
• the unit 6 also includes valves connection adapted to subject one or the other, or both bottles in series, to the gas mixture.
• the upstream bottle for example the bottle 30 becomes saturated more quickly than the downstream bottle, for example the bottle 32.
• the aforementioned valves are operated so that only the downstream bottle 32 is subjected to the gas mixture circulating in the production line 16. The time to replace the bottle 30 with a bottle with new or regenerated adsorbent material. This bottle 30 is then subjected, downstream of the bottle 32, to the gas mixture, and so on.
• FIG. 4 shows a second embodiment of the purification unit 24 according to the invention.
• the unit 24 comprises in this second mode a column 40 for washing with gas the gaseous mixture of the production line 16.
• the washing water used is free of solvent and the column 40 is, for example, a column with trays or packings.
• the unit 24 comprises a circuit 42 for circulating the washing water, comprising a drive pump 44, a purge bypass 46 and a make-up connection with clean water 48.
• the gas mixture is introduced into the bottom of column 40, while the washing water is introduced at the top.
• the aforementioned constituents, damaging by accumulation to the separation performance of the membrane unit 20, are then dissolved by the water descending in the column, the gaseous mixture being progressively purified as it rises in the column to finally be withdrawn at the head via line 22.
• the pump 44 ensures the circulation of the washing water from the tank to the head of the column, part of the water which borrows the circuit 42 being purged at 46 and replaced by an addition of clean water at 48.
• judiciously chosen chemicals can possibly be added to the washing water to improve the trapping of these constituents. Only the chemicals tolerated by the separation membranes of the unit 20 can be envisaged.
• FIG. 5 shows a variant of the second embodiment according to the invention, which has the advantage of integrating the respective columns 6A and 40 of the units 6 and 24 in a single washing column.
• the treatment unit 6 of the installation 1 generally comprises a column for washing with solvents, for example with amines. Furthermore, it is known in the art to produce, at the head of an amine washing column intended to purify the gaseous mixture of its acid impurities, in particular carbon dioxide, an isobaric closed loop of washing with water intended recovering amines, the latter being able to vaporize or disperse in the form of fine droplets in the outgoing gas flow.
• FIG. 5 there is shown a column 50 with three levels of trays.
• This column 50 consists in its upper part of the water washing column 40 of FIG. 4, in its lower part of the amine washing column 6A, and in its intermediate part of at least one tray 50A for recovering amines by dissolving the latter in water from circuit 42 of unit 24.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Analytical Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Combustion & Propulsion (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Carbon And Carbon Compounds (AREA)
• Gas Separation By Absorption (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=8869516

Family Applications (1)

Country Status (4)

Families Citing this family (9)

Family Cites Families (18)

• 2001
  • 2001-11-19 FR FR0114913A patent/FR2832326B1/fr not_active Expired - Lifetime
• 2002
  • 2002-11-13 WO PCT/FR2002/003877 patent/WO2003043720A1/fr not_active Ceased
  • 2002-11-13 US US10/496,232 patent/US6977007B2/en not_active Expired - Lifetime
  • 2002-11-13 EP EP02788050A patent/EP1450935A1/de not_active Ceased

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events