EP1979087A1 - Hazardous reactions in micro channel reactor - Google Patents

Hazardous reactions in micro channel reactor

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Publication number
EP1979087A1
EP1979087A1 EP06841524A EP06841524A EP1979087A1 EP 1979087 A1 EP1979087 A1 EP 1979087A1 EP 06841524 A EP06841524 A EP 06841524A EP 06841524 A EP06841524 A EP 06841524A EP 1979087 A1 EP1979087 A1 EP 1979087A1
Authority
EP
European Patent Office
Prior art keywords
heat exchange
oxygen
microchannel
mixing
ethylene
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP06841524A
Other languages
German (de)
French (fr)
Inventor
Jeroen Willem Bolk
Alouisius Nicolaas Renee Bos
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shell Internationale Research Maatschappij BV
Original Assignee
Shell Internationale Research Maatschappij BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shell Internationale Research Maatschappij BV filed Critical Shell Internationale Research Maatschappij BV
Priority to EP06841524A priority Critical patent/EP1979087A1/en
Publication of EP1979087A1 publication Critical patent/EP1979087A1/en
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/0093—Microreactors, e.g. miniaturised or microfabricated reactors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D301/00—Preparation of oxiranes
    • C07D301/02—Synthesis of the oxirane ring
    • C07D301/03—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds
    • C07D301/04—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with air or molecular oxygen
    • C07D301/08—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with air or molecular oxygen in the gaseous phase
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00781—Aspects relating to microreactors
    • B01J2219/00783—Laminate assemblies, i.e. the reactor comprising a stack of plates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00781—Aspects relating to microreactors
    • B01J2219/00819—Materials of construction
    • B01J2219/00822—Metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00781—Aspects relating to microreactors
    • B01J2219/00819—Materials of construction
    • B01J2219/00831—Glass
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00781—Aspects relating to microreactors
    • B01J2219/00819—Materials of construction
    • B01J2219/00833—Plastic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00781—Aspects relating to microreactors
    • B01J2219/00819—Materials of construction
    • B01J2219/00835—Comprising catalytically active material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00781—Aspects relating to microreactors
    • B01J2219/00851—Additional features
    • B01J2219/00858—Aspects relating to the size of the reactor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00781—Aspects relating to microreactors
    • B01J2219/00851—Additional features
    • B01J2219/00858—Aspects relating to the size of the reactor
    • B01J2219/0086—Dimensions of the flow channels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00781—Aspects relating to microreactors
    • B01J2219/00851—Additional features
    • B01J2219/00867—Microreactors placed in series, on the same or on different supports
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00781—Aspects relating to microreactors
    • B01J2219/00851—Additional features
    • B01J2219/00869—Microreactors placed in parallel, on the same or on different supports
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00781—Aspects relating to microreactors
    • B01J2219/00851—Additional features
    • B01J2219/00871—Modular assembly
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00781—Aspects relating to microreactors
    • B01J2219/00873—Heat exchange
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00781—Aspects relating to microreactors
    • B01J2219/00905—Separation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C2900/00—Special features of, or arrangements for combustion apparatus using fluid fuels or solid fuels suspended in air; Combustion processes therefor
    • F23C2900/03001—Miniaturized combustion devices using fluid fuels

Definitions

  • the present invention relates to improvements in process operations involving particularly hydrocarbons.
  • the process improvements envisaged find especial application in the production of olefin oxide from olefin and oxygen and in its optional further conversion.
  • process operations When operating on a commercial scale, process operations have to meet a number of important design criteria. In the modern day environment, process design has to take account of environmental legislation and keep to health and safety standards. Processes that utilise or produce dangerous chemicals pose particular problems and often, in order to minimise risks of explosion or reaction runaway, such process operations have to be run at conditions that are not optimal; this increases the running costs of a plant (the operational expenditure or OPEX) . Such processes may also have to utilise more equipment than is necessary just to perform the process; this leads to an increase in building costs (the capital expenditure or CAPEX) .
  • OPEX operational expenditure
  • CAPEX capital expenditure
  • the present invention provides for the utilisation of microchannel apparatus in process operations. Such apparatus have previously been proposed for use in certain specific fields of application but have not previously been proposed to provide the combination of reduced CAPEX and/or OPEX with maintained or reduced plant safety risks.
  • the invention provides a process for the mixing of an oxidant having explosive potential with a hydrocarbon material, which comprises conveying a first stream comprising the hydrocarbon material and a second stream comprising the oxidant into a microchannel apparatus, allowing mixing to occur, and withdrawing the mixture.
  • FIG. 1 shows a schematic drawing of a microchannel reactor and its main constituents.
  • FIG. 2 shows a schematic drawing of a typical example of a repeating unit which comprises process microchannels and heat exchange channels and its operation when in use in the practice of the invention.
  • a microchannel apparatus or reactor utilised in this invention may comprise a plurality of such repeating units .
  • FIG. 3 shows a schematic drawing of an example of a process for the preparation of ethylene oxide according to the invention. Detailed Description of the Invention
  • the present invention provides processes that utilise microchannel apparatus for physical operations.
  • MicroChannel reactors suitable for use in this invention and their operation have been described in WO-A-2004/099113, WO-A-01/12312 , WO-01/54812, US-A-6440895, US-A-6284217 , US-A-6451864 , US-A-6491880, US-A-6666909, US-A-6811829, US-A-6851171, US-A-6494614 , US-A-6228434 and US-A-6192596.
  • Methods by which the microchannel reactor may be manufactured and operated, as described in these references, may generally be applicable m the practice of the present invention.
  • microchannel reactor 100 may be comprised of a header 102, a plurality of process microchannels 104, and a footer 108.
  • the header 102 provides a passageway for fluid to flow into the process microchannels 104.
  • the footer 108 provides a passageway for fluid to flow from the process microchannels 104.
  • the number of process microchannels contained in a microchannel reactor may be very large.
  • the number may be up to 10 5 , or even up to 10 6 or up to 2 x 10 6 .
  • the number of process microchannels may be at least 10 or at least 100, or even at least 1000.
  • the process microchannels are typically arranged parallel, for example they may form an array of planar microchannels.
  • Each of the process microchannels may have at least one internal dimension of height or width of up to 15 mm, for example from 0.05 to 10 mm, in particular from 0.1 to 5 mm, more in particular from 0.5 to 2 mm.
  • the other internal dimension of height or width may be, for example, from 0.1 to 100 cm, in particular from
  • each of the process microchannels may be, for example, from 1 to 500 cm, in particular from 2 to 300 cm, more in particular from 3 to 200 cm, or from 5 to 100 cm.
  • the microchannel reactor 100 additionally comprises heat exchange channels (not shown in FIG. 1) which are in heat exchange contact with the process microchannels 104.
  • the heat exchange channels may be microchannels.
  • the microchannel reactor is adapted such that heat exchange fluid can flow from heat exchange header 110 through the heat exchange channels to heat exchange footer 112.
  • the heat exchange channels may be aligned to provide a flow m a co-current, counter-current or, in some aspects, preferably cross-current direction, relative to a flow in the process microchannels 104.
  • the cross-current direction is as indicated by arrows 114 and 116.
  • Each of the heat exchange channels may have at least one internal dimension of height or width of up to 15 mm, for example from 0.05 to 10 mm, m particular from 0.1 to 5 mm, more m particular from 0.5 to 2 mm.
  • the other internal dimension of height or width may be, for example, from 0.1 to 100 cm, in particular from 0.2 to 75 cm, more in particular from 0.3 to 50 cm.
  • the length of each of the heat exchange channels may be, for example, from 1 to 500 cm, in particular from 2 to 300 cm, more in particular from 3 to 200 cm, or from 5 to 100 cm.
  • the separation between each process microchannel 104 and the next adjacent heat exchange channel may be m the range of from 0.05 mm to 5 mm, in particular from 0.2 to 2 mm.
  • first heat exchange channels and second heat exchange channels there is provided for first heat exchange channels and second heat exchange channels, or first heat exchange channels, second heat exchange channels and third heat exchange channels, or even up to fifth heat exchange channels, or even further heat exchange channels.
  • first heat exchange channels and second heat exchange channels there is a plurality of sets of heat exchange channels, and accordingly there may be a plurality of heat exchange headers 110 and heat exchange footers 112, whereby each set of heat exchange channels may be adapted to receive heat exchange fluid from a heat exchange header 110 and to deliver heat exchange fluid into a heat exchange footer 112.
  • the header 102, footer 108, heat exchange header 110, heat exchange footer 112, process microchannels 104 and heat exchange channels may independently be made of any construction material which provides sufficient strength, optionally dimensional stability, and heat transfer characteristics to permit operation of the processes in accordance with this invention.
  • Suitable construction materials include, for example, steel (for example stainless steel and carbon steel), monel, titanium, copper, glass and polymer compositions.
  • the kind of heat exchange fluid is not material to the present invention and the heat exchange fluid may be selected from a large variety.
  • Suitable heat exchange fluids include steam, water, air and oils. In embodiments of the invention which include a plurality of sets of heat exchange channels, such sets of heat exchange channels may operate with different heat exchange fluids or with heat exchange fluids having different temperatures .
  • a microchannel reactor of use in the invention may comprise a plurality of repeating units each comprising one or more process microchannels and one or more heat exchange channels.
  • FIG. 2 shows a typical repeating unit and its operation.
  • Process microchannels 210 have an upstream end 220 and a downstream end 230 and may comprise of a first section 240.
  • First section 240 may be in heat exchange contact with first heat exchange channel 250, allowing heat exchange between first section 240 of process microchannel 210 and first heat exchange channel 250.
  • the repeating unit may comprise first feed channel 260 which leads into first section 240 through one or more first orifices 280.
  • first orifices 280 may be positioned downstream relative to another first orifice 280.
  • feed may enter into first section 240 of process microchannel 210 through an opening in upstream end 220 and/or through first feed channel 260 and one or more first orifices 280.
  • Process microchannels 210 may comprise a second section 340.
  • Second section 340 is positioned down stream of first section 240.
  • Second section 340 may be in heat exchange contact with second heat exchange channel 350, allowing heat exchange between second section 340 of process microchannel 210 and second heat exchange channel 350.
  • second section 340 is adapted to quench product obtained in and received from first section 240 by heat exchange with a heat exchange fluid in second heat exchange channel 350. Quenching if required may be achieved in stages by the presence of a plurality of second heat exchange channels 350, for example two or three or four.
  • Such a plurality of second heat exchange channels 350 may be adapted to contain heat exchange fluids having different temperatures, in particular such that in downstream direction of second section 340 heat exchange takes place with a second heat exchange channel 350 containing a heat exchange fluid having a lower temperature.
  • the repeating unit may comprise second feed channel 360 which leads into second section 340 through one or more second orifices 380. During operation, feed may enter into second section 340 from upstream in process microchannel 210 and through second feed channel 360 and one or more second orifices 380.
  • Process microchannels 210 may comprise an intermediate section 440, which is positioned downstream of first section 240 and upstream of second section 340. Intermediate section 440 may be m heat exchange contact with third heat exchange channel 450, allowing heat exchange between intermediate section 440 of the process microchannel 210 and third heat exchange channel 450.
  • process microchannel 210 may comprise a third section (not drawn) downstream of second section 340, and optionally a second intermediate section (not drawn) downstream of second section 340 and upstream of the third section.
  • the third section may be in heat exchange contact with a fourth heat exchange channel (not drawn) , allowing heat exchange between the third section of the process microchannel 210 and fourth heat exchange channel.
  • the second intermediate section may be in heat exchange contact with a fifth heat exchange channel (not drawn) , allowing heat exchange between the second intermediate section of the process microchannel 210 and fifth heat exchange channel.
  • the repeating unit may comprise a third feed channel (not drawn) which ends into the third section through one or more third orifices (not drawn) . Typically one or more third orifices may be positioned downstream relative to another third orifice. During operation, feed may enter into the third section from upstream in process microchannel 210 and through the third feed channel and the one or more third orifices.
  • Each of the feed channels may be a microchannel. They may have at least one internal dimension of height or width of up to 15 mm, for example from 0.05 to 10 mm, in particular from 0.1 to 5 mm, more in particular from 0.5 to 2 mm.
  • the other internal dimension of height or width may be, for example, from 0.1 to 100 cm, in particular from 0.2 to 75 cm, more in particular from 0.3 to 50 cm.
  • the length of each of the feed channels may be, for example, from 1 to 250 cm, in particular from
  • 2 to 150 cm more in particular from 3 to 100 cm, or from 5 to 50 cm.
  • the length of each of the sections of the process microchannels may be selected independently of each other, in accordance with, for example, the heat exchange capacity needed.
  • the lengths of the sections may independently be at least 1 cm, or at least 2 cm, or at least 5 cm.
  • the lengths of the sections may independently be at most 250 cm, or at most 150 cm, or at most 100 cm, or at most 50 cm.
  • Other dimensions of the sections are defined by the corresponding dimensions of process microchannel 210.
  • the microchannel reactor of this invention may be manufactured using known techniques, for example conventional machining, laser cutting, molding, stamping and etching and combinations thereof.
  • the microchannel reactor of this invention may be manufactured by forming sheets with features removed which allow passages. A stack of such sheets may be assembled to form an integrated device, by using known techniques, for example diffusion bonding, laser welding, cold welding, diffusion brazing, and combinations thereof.
  • the microchannel reactor of this invention comprises appropriate headers, footers, valves, conduit lines, and other features to control input of reactants, output of product, and flow of heat exchange fluids. These are not shown in the drawings, but they can be readily provided by those skilled in the art.
  • heat exchange equipment for temperature control of feed, in particular for heating feed or feed components, before it enters the process microchannels, or for temperature control of product, in particular for cooling product, after it has left the process microchannels.
  • Such further heat exchange equipment may be integral with the microchannel reactor, but more typically it will be separate equipment.
  • air or air enriched with oxygen is employed as a source of the oxidizing agent while in the oxygen-based processes, high purity (at least 95 mole%) oxygen is employed as the source of the oxidising agent.
  • high purity (at least 95 mole%) oxygen is employed as the source of the oxidising agent.
  • most epoxidation plants are oxygen-based.
  • the epoxidation process may be carried out using reaction temperatures selected from a wide range.
  • the reaction temperature within the epoxidation reactor is in the range of from 150 0 C to 340 0 C, more preferably in the range of from 180 to 325 0 C.
  • the reaction is preferably carried out at a pressure of in the range of from 1000 to 3500 kPa .
  • the mixing of oxidants and hydrocarbon materials is a hazardous process.
  • the oxidant is particularly oxygen gas
  • the mixing process has to be strictly controlled to minimise the mixing volume of oxygen gas following addition to the hydrocarbon material.
  • a mixture of the two materials has a minimum and a maximum oxygen level between which the mixture can become explosive.
  • the oxygen stream Prior to mixing, the oxygen stream has an oxygen level that exceeds the upper explosion limit, following mixing the aim would be for the oxygen level to be below the lower explosion limit.
  • the mixture will have an oxygen level that lies in the explosive region.
  • oxygen is reacted with ethylene in extremely large volumes.
  • this reaction is currently performed by addition of oxygen gas to a gas stream that contains ethylene and a ballast gas which may comprise one or more of nitrogen, carbon dioxide and methane.
  • the gas stream may also contain other gases such as ethane, oxygen, and argon following recycle, see US-A-3,119, 837 and EP-A-893,443 for example.
  • ethane, oxygen, and argon following recycle see US-A-3,119, 837 and EP-A-893,443 for example.
  • One such device is a mixing device in the shape of a ring or 'doughnut' , see Research Disclosure No. 465117, Research Disclosure Journal, January 2003, page 106, Kenneth Mason Publications Ltd.
  • the large volume of oxygen gas is still directly mixed into the gas flow, and there is still a region in the gas stream where the oxygen-gas mixture can be explosive, owing to pockets of not fully mixed gases.
  • mixing of oxidant and hydrocarbon occurs in one or more individual process microchannels .
  • the oxidant and the hydrocarbon are in the gas phase.
  • the oxidant stream and the hydrocarbon stream are desirably added via separate feed lines to common process microchannels.
  • the oxidant feed and the hydrocarbon feed is split up into multiple small volumes for the mixing to occur in individual process microchannels. This ensures a high efficiency of mixing and where the feeds are gases minimises the volume of gas that is in the explosive region. Inside the microchannels, explosion cannot take place as heat is immediately dissipated and the flame quenched making the apparatus intrinsically safe. When fully mixed, the mixture from each process microchannel will converge into one stream either within the microchannel apparatus or via a header into an external exit line, and a fully mixed stream is provided with minimal explosive risk.
  • one of the two feed streams preferably the hydrocarbon stream
  • enter one microchannel section 240 via process microchannels 260 and/or 220 and for this feed to be led via intermediate section 440 into a second section 340 wherein the other of the two feeds, preferably the oxidant, is introduced via second feed channel 360.
  • the microchannel apparatus may also comprise heat exchange channels, which may themselves be microchannels, through which a cooling medium can be run.
  • the oxidant is most preferably oxygen gas.
  • a hydrocarbon or hydrocarbon material herein may be any organic compound that contains hydrogen and carbon; other elements such as oxygen may also be present.
  • a hydrocarbon material may be one or more of hydrocarbons such as C ⁇ -io hydrocarbons, for example methane, ethylene, ethane, propylene, propane and butane; oxides such as C2-10 alkylene oxides, for example ethylene oxide; glycols such as C2-10 alkylene glycols for example mono-, di- or tri- ethylene glycol; and C ] __ ] _ Q organic acids such as acetic acid.
  • the process of the present invention may for example be utilised in the catalytic partial oxidation of ethylene to ethylene oxide or to vinyl acetate.
  • the present invention most suitably provides a process for the preparation of ethylene oxide, which comprises introducing a source of oxygen into one or more process microchannels of a microchannel apparatus and introducing into the same process microchannels a source of ethylene, allowing mixing to take place to form a gaseous product mixture, and conveying the gaseous product mixture to a reaction region wherein reaction to ethylene oxide can occur.
  • the source of ethylene comprises a mixture of ethylene and one or more compounds selected from methane, ethane, oxygen, argon, carbon dioxide and nitrogen.
  • the process of the present invention is most preferably utilised where the source of oxygen is oxygen gas having a purity in the range of from 95 to 99.99 % by volume; however the oxygen source may also be air or oxygen gas of a lower purity, for example of 85 % by volume and above, and thus preferably the oxygen source is a gas having an oxygen content in the range of from 15 to 99.99 % by volume .
  • the gases are mixed on a ⁇ microlevel' , i.e. on a very small scale, within process microchannels of the microchannel apparatus.
  • a ⁇ microlevel' i.e. on a very small scale
  • the splitting up and recombination of the oxygen flow in the process microchannels and, where present, via the microchannel orifices will establish an average oxygen concentration below explosion limits.
  • these pockets will disappear and the gases will become well-mixed on a microlevel.
  • a feed line suitably runs from the ethylene source into the apparatus, and a separate feed line is provided from the oxygen source.
  • the general process conditions that may apply for the mixing operation are suitably a pressure in the range of from 1000 to 3500 kPa, and a temperature in the range of from ambient (20 0 C) to 250 0 C.
  • the process of the present invention provides enhanced mixing in a rapid timescale, and indeed is able to provide a fully mixed product in a shorter timescale than previous proposals, particularly for the mixing of gases having an explosive potential.
  • microchannel apparatus provides the advantage of rapidly splitting up the feed gases and mixing small volumes together at a much faster rate than is achievable by the prior ring mixing devices.
  • the length of time that any mixture may exist in the explosive region is significantly reduced and the finally fully mixed gas stream is achieved much quicker.
  • the size of the microchannels themselves additionally ensures that the mixing apparatus functions as a flame arrester. For any gas or gas mixture there is a characteristic flame quench diameter; this is the diameter of pipe or container in which any flame would be quenched. By selection of the appropriate microchannel diameter it can be ensured that any starting combustion reaction can be immediately quenched.
  • a microchannel apparatus additionally may provide intrinsic safety for the mixing operation - this is not at all possible with current mixing systems. Where the microchannel apparatus additionally includes heat exchange channels, the safety advantages are further enhanced.
  • a microchannel apparatus having one or more, and preferably all, process microchannels having an internal dimension of height and/or width of at most 5 mm, most preferably at most 2 mm, and especially at most 1.5 mm.
  • Said internal dimension is preferably at least 0.1 mm, most preferably at least 0.5 mm, and especially at least 0.5 mm.
  • the stream of recycle gas to the reactor system is 600 mt/h.
  • This flow mainly consists of methane, ethylene, oxygen, argon, carbon dioxide and nitrogen.
  • the temperature at the reactor inlet is 14O 0 C and the pressure is 2000 kPa gauge .
  • ethylene and oxygen are consumed in the production of ethylene oxide (EO) and carbon dioxide (CO 2 ) .
  • EO ethylene oxide
  • CO 2 carbon dioxide
  • feed ethylene, via line 4, and oxygen, via line 5 are supplied to the recycle gas before entering the reactor 1.
  • 37.5 mt/h ethylene is fed to the recycle gas and 34.6 mt/h oxygen. From reactor 1 through absorber 2 and absorber 3 and back to the reactor 1, all of these sections plus the interconnecting pipework form the recycle gas loop.
  • the oxygen is mixed with the recycle gas in mixer 7.
  • Mixer 7 is a microchannel device such as described herein with respect to FIG. 1 and FIG. 2.
  • the microchannel devise ensures improved mixing of oxygen with recycle gas through multiple small volumes of gas being mixed in the individual microchannels reducing the impact of an explosion reaction. Explosions in such large volumes of flammable gases in a worldscale EO production facility have a huge impact and by use of the microchannel device in such a plant, the risk of an incident is decreased.

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Abstract

Process for preparing alkylene glycol by reacting the corresponding oxide and water by flowing these through a microchannel reactor and transferring the heat to a heat transfer medium. The reactor contains a catalyst suitablefor the hydrolysis. Process for preparing a mono-alkylene glycol by reacting the alkylene oxide and water under a first set of temperature/pressure conditions to achieve vapour phase conversion, altering the conditions to a second set of conditions and removing the glycols deposited on the surface of the catalyst, reestablishing the first set of conditions to repeat the first step and recovering the glycol from the vapour phase mixture .

Description

HAZARDOUS REACTIONS IN MICRO CHANNEL REACTOR
Field of the Invention
The present invention relates to improvements in process operations involving particularly hydrocarbons. The process improvements envisaged find especial application in the production of olefin oxide from olefin and oxygen and in its optional further conversion. Background of the Invention
When operating on a commercial scale, process operations have to meet a number of important design criteria. In the modern day environment, process design has to take account of environmental legislation and keep to health and safety standards. Processes that utilise or produce dangerous chemicals pose particular problems and often, in order to minimise risks of explosion or reaction runaway, such process operations have to be run at conditions that are not optimal; this increases the running costs of a plant (the operational expenditure or OPEX) . Such processes may also have to utilise more equipment than is necessary just to perform the process; this leads to an increase in building costs (the capital expenditure or CAPEX) .
There is an on-going need to provide process operations that can reduce CAPEX and OPEX costs and particularly without increasing the risk of damage to the plant and danger to the public and/or to the process plant workers. Summary of the Invention
The present invention provides for the utilisation of microchannel apparatus in process operations. Such apparatus have previously been proposed for use in certain specific fields of application but have not previously been proposed to provide the combination of reduced CAPEX and/or OPEX with maintained or reduced plant safety risks. The invention provides a process for the mixing of an oxidant having explosive potential with a hydrocarbon material, which comprises conveying a first stream comprising the hydrocarbon material and a second stream comprising the oxidant into a microchannel apparatus, allowing mixing to occur, and withdrawing the mixture.
This process finds special advantage when applied to the mixing of oxygen into the gas recycle stream in an ethylene oxide production plant. Brief Description of the Drawings FIG. 1 shows a schematic drawing of a microchannel reactor and its main constituents.
FIG. 2 shows a schematic drawing of a typical example of a repeating unit which comprises process microchannels and heat exchange channels and its operation when in use in the practice of the invention. A microchannel apparatus or reactor utilised in this invention may comprise a plurality of such repeating units .
FIG. 3 shows a schematic drawing of an example of a process for the preparation of ethylene oxide according to the invention. Detailed Description of the Invention
The present invention provides processes that utilise microchannel apparatus for physical operations. Hereinafter a discussion of such apparatus is given. MicroChannel reactors suitable for use in this invention and their operation have been described in WO-A-2004/099113, WO-A-01/12312 , WO-01/54812, US-A-6440895, US-A-6284217 , US-A-6451864 , US-A-6491880, US-A-6666909, US-A-6811829, US-A-6851171, US-A-6494614 , US-A-6228434 and US-A-6192596. Methods by which the microchannel reactor may be manufactured and operated, as described in these references, may generally be applicable m the practice of the present invention.
With reference to FIG. 1, microchannel reactor 100 may be comprised of a header 102, a plurality of process microchannels 104, and a footer 108. The header 102 provides a passageway for fluid to flow into the process microchannels 104. The footer 108 provides a passageway for fluid to flow from the process microchannels 104.
The number of process microchannels contained in a microchannel reactor may be very large. For example, the number may be up to 105, or even up to 106 or up to 2 x 106. Normally, the number of process microchannels may be at least 10 or at least 100, or even at least 1000.
The process microchannels are typically arranged parallel, for example they may form an array of planar microchannels. Each of the process microchannels may have at least one internal dimension of height or width of up to 15 mm, for example from 0.05 to 10 mm, in particular from 0.1 to 5 mm, more in particular from 0.5 to 2 mm. The other internal dimension of height or width may be, for example, from 0.1 to 100 cm, in particular from
0.2 to 75 cm, more in particular from 0.3 to 50 cm. The length of each of the process microchannels may be, for example, from 1 to 500 cm, in particular from 2 to 300 cm, more in particular from 3 to 200 cm, or from 5 to 100 cm.
The microchannel reactor 100 additionally comprises heat exchange channels (not shown in FIG. 1) which are in heat exchange contact with the process microchannels 104. The heat exchange channels may be microchannels. The microchannel reactor is adapted such that heat exchange fluid can flow from heat exchange header 110 through the heat exchange channels to heat exchange footer 112. The heat exchange channels may be aligned to provide a flow m a co-current, counter-current or, in some aspects, preferably cross-current direction, relative to a flow in the process microchannels 104. The cross-current direction is as indicated by arrows 114 and 116.
Each of the heat exchange channels may have at least one internal dimension of height or width of up to 15 mm, for example from 0.05 to 10 mm, m particular from 0.1 to 5 mm, more m particular from 0.5 to 2 mm. The other internal dimension of height or width may be, for example, from 0.1 to 100 cm, in particular from 0.2 to 75 cm, more in particular from 0.3 to 50 cm. The length of each of the heat exchange channels may be, for example, from 1 to 500 cm, in particular from 2 to 300 cm, more in particular from 3 to 200 cm, or from 5 to 100 cm. The separation between each process microchannel 104 and the next adjacent heat exchange channel may be m the range of from 0.05 mm to 5 mm, in particular from 0.2 to 2 mm.
In some embodiments of this invention, there is provided for first heat exchange channels and second heat exchange channels, or first heat exchange channels, second heat exchange channels and third heat exchange channels, or even up to fifth heat exchange channels, or even further heat exchange channels. Thus, m such cases, there is a plurality of sets of heat exchange channels, and accordingly there may be a plurality of heat exchange headers 110 and heat exchange footers 112, whereby each set of heat exchange channels may be adapted to receive heat exchange fluid from a heat exchange header 110 and to deliver heat exchange fluid into a heat exchange footer 112.
The header 102, footer 108, heat exchange header 110, heat exchange footer 112, process microchannels 104 and heat exchange channels may independently be made of any construction material which provides sufficient strength, optionally dimensional stability, and heat transfer characteristics to permit operation of the processes in accordance with this invention. Suitable construction materials include, for example, steel (for example stainless steel and carbon steel), monel, titanium, copper, glass and polymer compositions. The kind of heat exchange fluid is not material to the present invention and the heat exchange fluid may be selected from a large variety. Suitable heat exchange fluids include steam, water, air and oils. In embodiments of the invention which include a plurality of sets of heat exchange channels, such sets of heat exchange channels may operate with different heat exchange fluids or with heat exchange fluids having different temperatures .
A microchannel reactor of use in the invention may comprise a plurality of repeating units each comprising one or more process microchannels and one or more heat exchange channels. Reference is now made to FIG. 2, which shows a typical repeating unit and its operation.
Process microchannels 210 have an upstream end 220 and a downstream end 230 and may comprise of a first section 240. First section 240 may be in heat exchange contact with first heat exchange channel 250, allowing heat exchange between first section 240 of process microchannel 210 and first heat exchange channel 250. The repeating unit may comprise first feed channel 260 which leads into first section 240 through one or more first orifices 280. Typically one or more first orifices 280 may be positioned downstream relative to another first orifice 280. During operation, feed may enter into first section 240 of process microchannel 210 through an opening in upstream end 220 and/or through first feed channel 260 and one or more first orifices 280.
Process microchannels 210 may comprise a second section 340. Second section 340 is positioned down stream of first section 240. Second section 340 may be in heat exchange contact with second heat exchange channel 350, allowing heat exchange between second section 340 of process microchannel 210 and second heat exchange channel 350. In some embodiments second section 340 is adapted to quench product obtained in and received from first section 240 by heat exchange with a heat exchange fluid in second heat exchange channel 350. Quenching if required may be achieved in stages by the presence of a plurality of second heat exchange channels 350, for example two or three or four. Such a plurality of second heat exchange channels 350 may be adapted to contain heat exchange fluids having different temperatures, in particular such that in downstream direction of second section 340 heat exchange takes place with a second heat exchange channel 350 containing a heat exchange fluid having a lower temperature. The repeating unit may comprise second feed channel 360 which leads into second section 340 through one or more second orifices 380. During operation, feed may enter into second section 340 from upstream in process microchannel 210 and through second feed channel 360 and one or more second orifices 380.
The first and second feed channels 260 or 360 in combination with first and second orifices 280 or 380 whereby one or more first or second orifices 280 or 380 are positioned downstream to another first or second orifice 280 or 380, respectively, allow for replenishment of a reactant. Replenishment of a reactant can be utilised m some embodiments of this invention. Process microchannels 210 may comprise an intermediate section 440, which is positioned downstream of first section 240 and upstream of second section 340. Intermediate section 440 may be m heat exchange contact with third heat exchange channel 450, allowing heat exchange between intermediate section 440 of the process microchannel 210 and third heat exchange channel 450.
In some embodiments, process microchannel 210 may comprise a third section (not drawn) downstream of second section 340, and optionally a second intermediate section (not drawn) downstream of second section 340 and upstream of the third section. The third section may be in heat exchange contact with a fourth heat exchange channel (not drawn) , allowing heat exchange between the third section of the process microchannel 210 and fourth heat exchange channel. The second intermediate section may be in heat exchange contact with a fifth heat exchange channel (not drawn) , allowing heat exchange between the second intermediate section of the process microchannel 210 and fifth heat exchange channel. The repeating unit may comprise a third feed channel (not drawn) which ends into the third section through one or more third orifices (not drawn) . Typically one or more third orifices may be positioned downstream relative to another third orifice. During operation, feed may enter into the third section from upstream in process microchannel 210 and through the third feed channel and the one or more third orifices.
Each of the feed channels may be a microchannel. They may have at least one internal dimension of height or width of up to 15 mm, for example from 0.05 to 10 mm, in particular from 0.1 to 5 mm, more in particular from 0.5 to 2 mm. The other internal dimension of height or width may be, for example, from 0.1 to 100 cm, in particular from 0.2 to 75 cm, more in particular from 0.3 to 50 cm. The length of each of the feed channels may be, for example, from 1 to 250 cm, in particular from
2 to 150 cm, more in particular from 3 to 100 cm, or from 5 to 50 cm.
The length of each of the sections of the process microchannels may be selected independently of each other, in accordance with, for example, the heat exchange capacity needed. The lengths of the sections may independently be at least 1 cm, or at least 2 cm, or at least 5 cm. The lengths of the sections may independently be at most 250 cm, or at most 150 cm, or at most 100 cm, or at most 50 cm. Other dimensions of the sections are defined by the corresponding dimensions of process microchannel 210.
The microchannel reactor of this invention may be manufactured using known techniques, for example conventional machining, laser cutting, molding, stamping and etching and combinations thereof. The microchannel reactor of this invention may be manufactured by forming sheets with features removed which allow passages. A stack of such sheets may be assembled to form an integrated device, by using known techniques, for example diffusion bonding, laser welding, cold welding, diffusion brazing, and combinations thereof. The microchannel reactor of this invention comprises appropriate headers, footers, valves, conduit lines, and other features to control input of reactants, output of product, and flow of heat exchange fluids. These are not shown in the drawings, but they can be readily provided by those skilled in the art. Also, there may be further heat exchange equipment (not shown in the drawings) for temperature control of feed, in particular for heating feed or feed components, before it enters the process microchannels, or for temperature control of product, in particular for cooling product, after it has left the process microchannels. Such further heat exchange equipment may be integral with the microchannel reactor, but more typically it will be separate equipment. These are not shown in the drawings, but they can be readily provided by those skilled in the art. The present invention in certain aspects finds especial application in a process for the manufacture of alkylene oxide, and especially ethylene oxide, by the direct epoxidation of alkylene using oxygen or air, see Kirk-Othmer Encyclopedia of Chemical Technology, 3rd edition, Volume 9, 1980, pages 445 to 447. In the air-based process, air or air enriched with oxygen is employed as a source of the oxidizing agent while in the oxygen-based processes, high purity (at least 95 mole%) oxygen is employed as the source of the oxidising agent. Currently most epoxidation plants are oxygen-based. The epoxidation process may be carried out using reaction temperatures selected from a wide range. Preferably the reaction temperature within the epoxidation reactor is in the range of from 150 0C to 340 0C, more preferably in the range of from 180 to 325 0C. The reaction is preferably carried out at a pressure of in the range of from 1000 to 3500 kPa .
The mixing of oxidants and hydrocarbon materials is a hazardous process. Where the oxidant is particularly oxygen gas, the mixing process has to be strictly controlled to minimise the mixing volume of oxygen gas following addition to the hydrocarbon material.
Considering the mixing of oxygen gas and a hydrocarbon material such as ethylene, a mixture of the two materials has a minimum and a maximum oxygen level between which the mixture can become explosive. Prior to mixing, the oxygen stream has an oxygen level that exceeds the upper explosion limit, following mixing the aim would be for the oxygen level to be below the lower explosion limit. However during mixing there will inevitably be a stage where the mixture will have an oxygen level that lies in the explosive region.
It is therefore advantageous to have a mixing process that minimises the length of time that an oxidant- hydrocarbon mixture exists in the relevant explosive region.
In the commercial production of ethylene oxide, oxygen is reacted with ethylene in extremely large volumes. In commercial operations this reaction is currently performed by addition of oxygen gas to a gas stream that contains ethylene and a ballast gas which may comprise one or more of nitrogen, carbon dioxide and methane. Additionally the gas stream may also contain other gases such as ethane, oxygen, and argon following recycle, see US-A-3,119, 837 and EP-A-893,443 for example. Minimising the risk of explosion following addition of significant volumes of oxygen gas to the gas stream is of prime concern. Specific devices have been developed to ensure rapid mixing and to minimise the volume of gas in the gas stream that exists in the explosive region i.e. to minimise the volume of not fully mixed gases. One such device is a mixing device in the shape of a ring or 'doughnut' , see Research Disclosure No. 465117, Research Disclosure Journal, January 2003, page 106, Kenneth Mason Publications Ltd. However with such devices the large volume of oxygen gas is still directly mixed into the gas flow, and there is still a region in the gas stream where the oxygen-gas mixture can be explosive, owing to pockets of not fully mixed gases. By the use of microchannel apparatus, mixing of oxidant and hydrocarbon occurs in one or more individual process microchannels . Preferably the oxidant and the hydrocarbon are in the gas phase. The oxidant stream and the hydrocarbon stream are desirably added via separate feed lines to common process microchannels. Since there exists a large number of process microchannels within a microchannel apparatus, the oxidant feed and the hydrocarbon feed is split up into multiple small volumes for the mixing to occur in individual process microchannels. This ensures a high efficiency of mixing and where the feeds are gases minimises the volume of gas that is in the explosive region. Inside the microchannels, explosion cannot take place as heat is immediately dissipated and the flame quenched making the apparatus intrinsically safe. When fully mixed, the mixture from each process microchannel will converge into one stream either within the microchannel apparatus or via a header into an external exit line, and a fully mixed stream is provided with minimal explosive risk.
Having regard to FIG. 2 herewith, it is possible, for example, for one of the two feed streams, preferably the hydrocarbon stream, to enter one microchannel section 240 via process microchannels 260 and/or 220, and for this feed to be led via intermediate section 440 into a second section 340 wherein the other of the two feeds, preferably the oxidant, is introduced via second feed channel 360. Mixing of the two feeds can then occur in the microchannel 230 to which the second feed is directed via orifices 380. If necessary for the feed components involved or to provide enhanced safety, the microchannel apparatus may also comprise heat exchange channels, which may themselves be microchannels, through which a cooling medium can be run. In the present invention, the oxidant is most preferably oxygen gas. A hydrocarbon or hydrocarbon material herein may be any organic compound that contains hydrogen and carbon; other elements such as oxygen may also be present. In this aspect of the present invention a hydrocarbon material may be one or more of hydrocarbons such as C^-io hydrocarbons, for example methane, ethylene, ethane, propylene, propane and butane; oxides such as C2-10 alkylene oxides, for example ethylene oxide; glycols such as C2-10 alkylene glycols for example mono-, di- or tri- ethylene glycol; and C]__]_Q organic acids such as acetic acid. Thus, the process of the present invention may for example be utilised in the catalytic partial oxidation of ethylene to ethylene oxide or to vinyl acetate.
The present invention most suitably provides a process for the preparation of ethylene oxide, which comprises introducing a source of oxygen into one or more process microchannels of a microchannel apparatus and introducing into the same process microchannels a source of ethylene, allowing mixing to take place to form a gaseous product mixture, and conveying the gaseous product mixture to a reaction region wherein reaction to ethylene oxide can occur. Preferably the source of ethylene comprises a mixture of ethylene and one or more compounds selected from methane, ethane, oxygen, argon, carbon dioxide and nitrogen. The process of the present invention is most preferably utilised where the source of oxygen is oxygen gas having a purity in the range of from 95 to 99.99 % by volume; however the oxygen source may also be air or oxygen gas of a lower purity, for example of 85 % by volume and above, and thus preferably the oxygen source is a gas having an oxygen content in the range of from 15 to 99.99 % by volume .
In this aspect of the present invention, the gases are mixed on a λmicrolevel' , i.e. on a very small scale, within process microchannels of the microchannel apparatus. Initially after intermingling of both feeds there will of course be pockets of oxygen-rich and oxygen-poor mixtures, however the splitting up and recombination of the oxygen flow in the process microchannels and, where present, via the microchannel orifices, will establish an average oxygen concentration below explosion limits. As the gas mixture progresses through the microchannel apparatus, these pockets will disappear and the gases will become well-mixed on a microlevel. In an EO manufacturing plant, it is most useful to locate the microchannel apparatus in the recycle gas loop at the same location where conventional mixing apparatus is utilised i.e. prior to the reactor. However it is possible to locate the microchannel apparatus at any location in the recycle gas loop. In certain locations the conditions of the gas, for example its composition, pressure and/or temperature, could cause even the final well-mixed gas to be in the explosive region; in such circumstances it may be necessary to adjust the conditions to allow the process of the invention to be used, for example to reduce the temperature of the recycle gas stream. A feed line suitably runs from the ethylene source into the apparatus, and a separate feed line is provided from the oxygen source. The general process conditions that may apply for the mixing operation are suitably a pressure in the range of from 1000 to 3500 kPa, and a temperature in the range of from ambient (20 0C) to 250 0C. The process of the present invention provides enhanced mixing in a rapid timescale, and indeed is able to provide a fully mixed product in a shorter timescale than previous proposals, particularly for the mixing of gases having an explosive potential.
Thus the use of the microchannel apparatus provides the advantage of rapidly splitting up the feed gases and mixing small volumes together at a much faster rate than is achievable by the prior ring mixing devices. The length of time that any mixture may exist in the explosive region is significantly reduced and the finally fully mixed gas stream is achieved much quicker.
The size of the microchannels themselves additionally ensures that the mixing apparatus functions as a flame arrester. For any gas or gas mixture there is a characteristic flame quench diameter; this is the diameter of pipe or container in which any flame would be quenched. By selection of the appropriate microchannel diameter it can be ensured that any starting combustion reaction can be immediately quenched. Thus the physical nature of a microchannel apparatus additionally may provide intrinsic safety for the mixing operation - this is not at all possible with current mixing systems. Where the microchannel apparatus additionally includes heat exchange channels, the safety advantages are further enhanced.
In a process of the present invention, it is thus preferred to use a microchannel apparatus having one or more, and preferably all, process microchannels having an internal dimension of height and/or width of at most 5 mm, most preferably at most 2 mm, and especially at most 1.5 mm. Said internal dimension is preferably at least 0.1 mm, most preferably at least 0.5 mm, and especially at least 0.5 mm. The present invention will now be illustrated by the following Example. Example
In a 400,000 mt/a ethylene oxide plant the stream of recycle gas to the reactor system is 600 mt/h. This flow mainly consists of methane, ethylene, oxygen, argon, carbon dioxide and nitrogen. The temperature at the reactor inlet is 14O0C and the pressure is 2000 kPa gauge . In FIG. 3, over the catalyst inside the reactor 1, ethylene and oxygen are consumed in the production of ethylene oxide (EO) and carbon dioxide (CO2) . After scrubbing the reaction product gases with water to absorb EO in EO absorber 2, and scrubbing part of the recycle gas of CO2 in CO2 absorber 3, feed ethylene, via line 4, and oxygen, via line 5, are supplied to the recycle gas before entering the reactor 1. 37.5 mt/h ethylene is fed to the recycle gas and 34.6 mt/h oxygen. From reactor 1 through absorber 2 and absorber 3 and back to the reactor 1, all of these sections plus the interconnecting pipework form the recycle gas loop.
The oxygen is mixed with the recycle gas in mixer 7. Mixer 7 is a microchannel device such as described herein with respect to FIG. 1 and FIG. 2. The microchannel devise ensures improved mixing of oxygen with recycle gas through multiple small volumes of gas being mixed in the individual microchannels reducing the impact of an explosion reaction. Explosions in such large volumes of flammable gases in a worldscale EO production facility have a huge impact and by use of the microchannel device in such a plant, the risk of an incident is decreased.

Claims

C L A I M S
1. A process for the mixing of an oxidant having explosive potential with a hydrocarbon material, which comprises conveying a first stream comprising the hydrocarbon material and a second stream comprising the oxidant into a microchannel apparatus, allowing mixing to occur, and withdrawing the mixture .
2. A process for the preparation of ethylene oxide, which comprises introducing a source of oxygen into one or more process microchannels of a microchannel apparatus and introducing into the same process microchannels a source of ethylene, allowing mixing to take place to form a gaseous product mixture, and conveying the gaseous product mixture to a reaction region wherein reaction to ethylene oxide can occur.
3. A process as claimed in claim 2, wherein the microchannel apparatus is located in the recycle gas loop of an ethylene oxide manufacturing plant .
4. A process as claimed in claim 2 or claim 3, wherein the source of ethylene comprises a mixture of ethylene and one or more of ethane, oxygen, argon, carbon dioxide, nitrogen and methane, and the source of oxygen is a gas having an oxygen content in the range of from 15 to 99.99% by volume.
5. A process as claimed in any one of claims 1 to 4, wherein the microchannel apparatus comprises one or more process microchannels having an internal height and/or width in the range of from 0.5 to 1.5 mm.
EP06841524A 2005-12-22 2006-12-20 Hazardous reactions in micro channel reactor Withdrawn EP1979087A1 (en)

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KR20080080184A (en) 2008-09-02
CA2634409A1 (en) 2007-06-28
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CA2634440A1 (en) 2007-06-28
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CA2634366A1 (en) 2007-06-28
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