EP2596312A2 - Séparation d'un mélange gazeux - Google Patents

Séparation d'un mélange gazeux

Info

Publication number
EP2596312A2
EP2596312A2 EP11734170.1A EP11734170A EP2596312A2 EP 2596312 A2 EP2596312 A2 EP 2596312A2 EP 11734170 A EP11734170 A EP 11734170A EP 2596312 A2 EP2596312 A2 EP 2596312A2
Authority
EP
European Patent Office
Prior art keywords
stream
carbon dioxide
compressor
liquid
gas
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Withdrawn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
EP11734170.1A
Other languages
German (de)
English (en)
Inventor
Jonathan Alec Forsyth
Yasushi Mori
Hideki Nagao
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.)
BP Technology Ventures Ltd
Original Assignee
BP Technology Ventures Ltd
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 BP Technology Ventures Ltd filed Critical BP Technology Ventures Ltd
Priority to EP11734170.1A priority Critical patent/EP2596312A2/fr
Publication of EP2596312A2 publication Critical patent/EP2596312A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/08—Separating gaseous impurities from gases or gaseous mixtures or from liquefied gases or liquefied gaseous mixtures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/58—Cooling; Heating; Diminishing heat transfer
    • F04D29/582—Cooling; Heating; Diminishing heat transfer specially adapted for elastic fluid pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D27/00—Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids
    • F04D27/02—Surge control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/58—Cooling; Heating; Diminishing heat transfer
    • F04D29/582—Cooling; Heating; Diminishing heat transfer specially adapted for elastic fluid pumps
    • F04D29/5846—Cooling; Heating; Diminishing heat transfer specially adapted for elastic fluid pumps cooling by injection
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/06—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation
    • F25J3/0605—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the feed stream
    • F25J3/0625—H2/CO mixtures, i.e. synthesis gas; Water gas or shifted synthesis gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/06—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation
    • F25J3/063—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the separated product stream
    • F25J3/0655—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the separated product stream separation of hydrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/06—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation
    • F25J3/063—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the separated product stream
    • F25J3/067—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the separated product stream separation of carbon dioxide
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/30—Processes or apparatus using other separation and/or other processing means using a washing, e.g. "scrubbing" or bubble column for purification purposes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2210/00—Processes characterised by the type or other details of the feed stream
    • F25J2210/04—Mixing or blending of fluids with the feed stream
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2220/00—Processes or apparatus involving steps for the removal of impurities
    • F25J2220/80—Separating impurities from carbon dioxide, e.g. H2O or water-soluble contaminants
    • F25J2220/82—Separating low boiling, i.e. more volatile components, e.g. He, H2, CO, Air gases, CH4
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/20—Integrated compressor and process expander; Gear box arrangement; Multiple compressors on a common shaft
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/30—Compression of the feed stream
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/70—Steam turbine, e.g. used in a Rankine cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/02—Recycle of a stream in general, e.g. a by-pass stream
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/04—Internal refrigeration with work-producing gas expansion loop
    • F25J2270/06—Internal refrigeration with work-producing gas expansion loop with multiple gas expansion loops
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/90—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2280/00—Control of the process or apparatus
    • F25J2280/02—Control in general, load changes, different modes ("runs"), measurements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2280/00—Control of the process or apparatus
    • F25J2280/10—Control for or during start-up and cooling down of the installation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2280/00—Control of the process or apparatus
    • F25J2280/20—Control for stopping, deriming or defrosting after an emergency shut-down of the installation or for back up system
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/40—Capture or disposal of greenhouse gases of CO2

Definitions

  • the present invention relates to the separation of a gas mixture. Aspects of the invention provide separation of a component from a mixture of gases. Aspects of the invention relate to the separation of a relatively more condensable gas from a mixture in which it is mixed with one or more relatively less condensable gases. In particular, but not exclusively, aspects of the invention relate to the separation of carbon dioxide from a stream comprising carbon oxide(s). In some examples, the stream further includes hydrogen.
  • a method for use in the separation of carbon dioxide from a feed stream comprising carbon oxide(s) and hydrogen.
  • gases such as carbon monoxide, methane, ethane and natural gas are required to have a purity above a particular threshold for use in certain applications.
  • gases such as carbon monoxide, methane, ethane and natural gas are required to have a purity above a particular threshold for use in certain applications.
  • a method for use in the separation of carbon dioxide from a gas mixture comprising carbon dioxide comprising the steps of: (i) compressing and cooling the gas mixture using a compressor to form a two-phase mixture including liquid carbon dioxide (ii) separating a liquid carbon dioxide stream from the two-phase mixture; and (iii) recirculating at least a part of the liquid carbon dioxide stream and introducing the recirculated liquid stream into a process stream
  • cooling of the process stream can be obtained.
  • additional cooling is possible as cooling is effected by the evaporation of the liquid C0 2 .
  • the recirculated liquid can be used to reduce the temperature of the process stream.
  • liquid C0 2 stream may be introduced at any region of the system at which the cooling is required.
  • the C0 2 liquid stream may include a plurality of sub-streams, each sub-stream may be directed to a region of system.
  • the recirculated C0 2 liquid stream is introduced upstream of the compressor.
  • additional advantages can be obtained. For example, by recirculating C0 2 in liquid form, the compression power of the compressor can be reduced. Also, by recirculating C0 2 , the feed flow through the compressor can be increased by the addition of the C0 2 stream. Thus problems associated with low flow through a compressor and/or variable flow through a compressor can be reduced or eliminated. If the feed flow through a compressor is reduced, C0 2 can be recirculated to ensure sufficient compressor flow. Thus the system can remain operational even when the feed flow is reduced to what may otherwise be below the operating flow rate for components of the system.
  • compressor surge can occur if flow rates through the compressor fall too low and can cause an abrupt reversal of the airflow through the unit, as the pumping action of the aerofoils stalls.
  • a gaseous stream is preferably fed to the compressor and at least a part of the recirculated liquid carbon dioxide stream is preferably introduced into the gaseous stream, such that the liquid carbon dioxide evaporates before entering the compressor.
  • the gaseous stream may be for example the feed stream of the compressor, but can be any gaseous stream that is suitable for ensuring that the carbon dioxide evaporates, and preferably mixes efficiently, when being introduced into the gaseous stream and before the mixed stream reaches the compressor inlet.
  • the gaseous stream may be a hydrogen rich gas stream, or a synthesis gas stream.
  • the said stream may at least partly be derived from a hydrogen rich gas stream from which the liquid C0 2 is separated in a gas-liquid separator vessel.
  • the entire liquid carbon dioxide stream that is taken from the gas-liquid separator vessel is recirculated indirectly, or directly, to upstream of the compressor.
  • the entire liquid carbon dioxide stream is first evaporated in the gaseous stream before being recirculated to the compressor.
  • liquid carbon dioxide is at a temperature of above -56 deg C.
  • the recirculated liquid carbon dioxide before being introduced into the gaseous stream, is at a temperature of between -40 °C and 70 °C and preferably between 30 and 50 °C; and at a pressure of between 1 and 20 Mpa, preferably between 10 and 15 MPa.
  • the temperature is such that the carbon dioxide cools on expansion.
  • the carbon dioxide is substantially at ambient temperature.
  • the gas mixture may further include hydrogen, the two phase mixture comprising liquid carbon dioxide and a hydrogen rich gas, wherein the hydrogen rich gas is separated from the two-phase mixture and at least a part of the separated hydrogen rich gas stream is recirculated to the compressor.
  • the gaseous stream which is preferably a hydrogen rich gas stream, is preferably the same hydrogen rich gas stream that is separated from the carbon dioxide stream.
  • the entire hydrogen rich gas stream that is taken from the separator is recirculated indirectly, or directly, to the compressor.
  • the gaseous stream is preferably at a temperature of between 10 and 70 °C, preferably between 30 and 50 °C; and at a pressure of between 0.5 and 15 MPa, preferably between 1 and 12 MPa.
  • the stream may be at substantially ambient temperature.
  • the pressure may be between 3 and 20 MPa, for example between 3.5 and 12 MPa, preferably between 3.5 and 5.5 MPa.
  • the gaseous stream that is fed to the compressor may be a hydrogen rich gas stream.
  • the recirculated liquid carbon dioxide is sprayed into the gaseous stream.
  • the recirculated liquid carbon dioxide may be introduced into the gaseous stream by any suitable method.
  • the method of introduction is suitable for achieving a sufficient level of evaporation of the liquid carbon dioxide in the gaseous stream before the carbon dioxide reaches the compressor.
  • a sufficient level of evaporation is where the carbon dioxide is in a suitable state/phase/droplet size distribution for being fed to the compressor.
  • the recirculated liquid carbon dioxide may be sprayed into the gaseous stream using an atomising nozzle.
  • a nozzle can be used to introduce the liquid carbon dioxide into the gaseous stream
  • suitable nozzles include atomising nozzles, such as liquid- only spray-type nozzles or gas-induced atomising nozzles, where gas is used to assist in the injection of the liquid.
  • the recirculated liquid carbon dioxide may be sprayed into the gaseous stream using a venturi nozzle.
  • the flow path from the introduction of the carbon dioxide to the inlet of the compressor is such that substantially all of the liquid carbon dioxide has evaporated upstream of the compressor inlet.
  • the length of the flow path is such that evaporation is substantially complete upstream of the compressor.
  • Other features can be provided to increase the rate of evaporation. For example a formation for increasing turbulent flow in the nozzle and/or the flow path, can be provided.
  • the recirculated liquid carbon dioxide may be sprayed into a pipe, that is preferably at least 2m in length.
  • the pipe may be for example of the order of 3m in flow length.
  • the pipe may have a serpentine configuration.
  • the particle size of the liquid carbon dioxide entering into the gaseous stream may be less than 200 ⁇ .
  • the applicants have found that the degree of evaporation of the liquid carbon dioxide in the gaseous stream is especially high when a small particle size of sprayed particles is used.
  • the particle size of the liquid carbon dioxide droplets is preferably less than 200 ⁇ and even more preferably when the droplets are 150 ⁇ or less. In the example below, the droplet size of the sprayed particles is not more than 150 ⁇ . Preferably at least 90%, preferably at least 95%, preferably at least 99% of the droplets have a size less of 150 microns or less.
  • substantially all of the liquid carbon dioxide stream is introduced into the gaseous stream.
  • the applicants have also found that a high degree of evaporation could be achieved by introducing the liquid carbon dioxide stream into the gaseous stream, by any of the methods mentioned above, within one or more pipes.
  • the method of introducing the liquid carbon dioxide includes use of apparatus having a plurality of feed pipes, the method including spraying liquid carbon dioxide into each of the feed pipes.
  • it was particularly advantageous towards evaporation of the liquid carbon dioxide when the liquid carbon dioxide was introduced at the bottom of the pipe(s) and where the pipe(s) is/are between 2m and 4m in length, and/or where the liquid carbon dioxide flowed at a rate of 3m/s.
  • the mixture of the gaseous stream and carbon dioxide within this pipe(s), is preferably at a temperature of less than 0 °C and a pressure of between 0.5 and 15 Mpa, preferably between 2 and 12 MPa.
  • the compressor may for example discharge the mixed stream at a temperature of above 5 °C and at a pressure of between 1 and 15 Mpa, preferably between 10 and 15 MPa.
  • a part of the separated liquid carbon dioxide may also be added to an additional point of the process.
  • liquid carbon dioxide could also be added to the stream discharged by the first compressor, by any suitable method known to those skilled in the art, but preferably by using one or more of the spray nozzles and/or pipes that are described herein. Therefore, in this case, the gaseous stream that the liquid carbon dioxide is evaporated into will at least partly be the discharged mixture from the first compressor and not the recirculated hydrogen rich gas stream.
  • the new mixture temperature may then be reduced by the order of up to 60 °C and passed to a second compressor. This additional liquid carbon dioxide introduction can be repeated as many times as required.
  • the applicants have found that by introducing the liquid carbon dioxide stream into the gaseous stream, they were not only able to benefit from the cooling effect of adding cold liquid carbon dioxide to the process stream, but once the liquid carbon dioxide had evaporated within the gaseous stream, they were also able to benefit from the extra cooling from the latent heat of the liquid carbon dioxide evaporation.
  • This is particularly advantageous in a process that involves compressors, because this extra degree of cooling has the advantage of reducing the compression power of the compressor(s) involved in the process and therefore represents a significant economic advantage compared to recycling warm streams.
  • the first compressor When the liquid carbon dioxide is recirculated to two or more compressors arranged in series, the first compressor will benefit not only from the cooling of the carbon dioxide stream but also from an increase in gas flow rate through the compressor. Subsequent downstream compressors can also benefit from additional cooling effect associated with further circulated liquid carbon dioxide introduction to the compressor, which is described herein.
  • a further aspect of the present invention provides a method for use in the separation of carbon dioxide from a feed stream comprising carbon oxide(s) in an apparatus including a compressor, the method comprising the following steps:
  • aspects of the invention can be used in systems where carbon dioxide and/or other product streams are recirculated through the system, for example as in a demonstration or research system. Additionally, the applicants have identified that the methods of aspects of the present invention can provide advantageous benefits in other applications, for example in the operation of apparatus for separation of carbon dioxide from a mixed gas. For example, as discussed further below, aspects of the invention can be applied to a procedure for "starting-up" a process, for example a process for separating carbon dioxide from a mixed gas, wherein the mixed gas may be for example a carbon oxide(s) and hydrogen feedstock.
  • the applicants have further identified potential advantageous application of aspects of the invention in methods of operating a carbon dioxide separation system where gas flow rate, during operation of the system drops to a value below optimum operation flow for one or more components of the system, for example below an optimum operation flow for a compressor in the system.
  • gas flow rate during operation of the system drops to a value below optimum operation flow for one or more components of the system, for example below an optimum operation flow for a compressor in the system.
  • compressor surge may become an issue for any one or more of the compressors in the process.
  • the gas flow rate in the system can be increased for example to at least a part, or preferably to the all, of the compressors in that process.
  • a flexible mode of operating a separation process where the amount of carbon dioxide recirculated to particular components of the system, for example to the compressor, can be controlled depending on a parameter of the system, for example the gas flow rate to one or more of the compressor(s).
  • control could be carried out manually or automatically, for example under at least partial control of a electronic controller.
  • the invention may further comprise the steps of: determining information relating to a parameter of the system, and controlling the recirculation of carbon dioxide on the basis of the determined information.
  • the control of recirculation may relate for example to the proportion of carbon dioxide which is recirculated compared with that removed from the system, and/or to the location of the introduction of the recirculated carbon dioxide, where there is more than one possible recirculation path in the system.
  • a further aspect of the invention provides a method for use in a system for the separation of carbon dioxide from a feed stream comprising carbon oxide(s) in an apparatus including a compressor, the method comprising the following steps: (i) compressing and cooling the feed stream to form a two-phase mixture including carbon dioxide; and
  • the method further includes determining information relating to a parameter of the system, and controlling the recirculation of carbon dioxide on the basis of the determined information, for example information relating to flow rate of a stream and/or information relating to the compressor surge of one or more compressors.
  • the recirculation of the carbon dioxide is controlled so that a process parameter is maintained within a predetermined value range.
  • the process parameter is maintained within a predetermined value range.
  • recirculation of the carbon dioxide may be controlled so that the feed flow rate is maintained to within a predetermined set of values of flow rate.
  • the flow rate or other parameter is maintained at a predetermined value.
  • the method may further include the steps of: (i) determining the gas flow rate of the process; (ii) controlling the amount of carbon dioxide that is recirculated on the basis of the determined gas flow rate.
  • the system may include for example a gas flow monitoring device which is arranged to transmit information relating to the gas flow rate to a control device, the control device transmitting control instructions which are used to control the recirculation of the carbon dioxide.
  • this aspect of the invention is particularly advantageous, as not only does it aid in increasing the gas flow rate to at least a part, preferably all, of the compressors in the process but it also provides a cooling benefit, as the carbon dioxide stream is typically cooler than the stream that it is introduced into.
  • the recirculation is adjusted to increase the recirculation to upstream of that compressor.
  • the gas flow rate of the compressor is 80 % of "compressor surge” flow rate
  • 35% more preferably 30% of "compressor surge” flow rate equivalent of the carbon dioxide drawn from the separator will be recirculated to the compressor(s); preferably using the methods having one or more of the features described herein.
  • the carbon dioxide stream may be recirculated in the liquid state.
  • the mixed gas may include carbon oxide(s) and hydrogen, and preferably is a synthesis gas stream.
  • the gas flow rate of the carbon oxide(s) in hydrogen feed stream is between 40 to 45%.
  • At least a part of the carbon oxide(s) and hydrogen feed stream that exits the compressor may be recirculated back to the compressor.
  • the recirculated carbon dioxide stream may be split into a plurality of sub streams, each substream being introduced in one or a plurality of introduction points in the process.
  • the carbon dioxide stream may be recirculated to any one or more points throughout the process, for example the recirculated carbon dioxide may be fed to two different compressors in order to seek to improve cooling and/or improve operation of the compressors, for example to reduce the chance of "compressor surge".
  • At least a part of the carbon dioxide stream may be removed from the system.
  • o as fuel gas feed e.g. for a combustor of a gas turbine of a power plant, o as a feed to an expander (preferably a turbo expander) which, due to the expansion of the hydrogen rich vapour stream, may be used to drive a rotor or shaft of a compressor and/or to drive the rotor or shaft of an electric generator, and
  • an expander preferably a turbo expander
  • underground strata ); and/or use in a wide range of other applications, e.g. in the food, chemical and oil and gas industry, and
  • the present invention also provides a method for use in a process for separating a synthesis gas stream into a hydrogen rich gaseous stream and a purified liquid carbon dioxide stream in a carbon dioxide condensation plant that comprises a heat exchanger system, a gas-liquid separator vessel, and an expansion system comprising at least one expander.
  • the present invention provides a method according to any of the preceding claims wherein the gas mixture includes hydrogen and a hydrogen rich stream is separated from the gas mixture, wherein at least a part of the hydrogen rich gas stream is fed to an expansion system wherein it is subjected to isentropic expansion in an expander, such that a hydrogen rich gas stream is withdrawn from the expander at reduced temperature and reduced pressures and wherein isentropic expansion of the hydrogen rich gas in the expander generates motive power.
  • a series of expanders can be provided. Where expanders are arranged in series, preferably the cooled stream between the expanders is used to effect heat exchange with one or more other process streams.
  • the motive power that is generated can advantageously be used to drive a machine that is a component of for example, a carbon dioxide condensation plant and/or for driving an alternator of an electric generator.
  • the machine that is driven by the expander(s) is preferably one or more compressor(s), and/or a pump, for example, for pumping liquid carbon dioxide.
  • the electricity is preferably used to power one or more components of the carbon dioxide condensation plant.
  • compression and cooling is required to bring the gas mixture to a two-phase mixture including liquid carbon dioxide.
  • a high pressure gas mixture for example including carbon oxide(s) and hydrogen
  • the mixture is cooled to a temperature in the range of -15 to -55°C. This is preferably performed by passing the gas mixture through a heat exchanger system.
  • the mixture will be passed in heat exchange relationship with at least one coolant stream; a plurality of coolant streams are preferably used.
  • the coolant streams are preferably "internal" streams which are produced as a part of the process wherein the internal streams are selected from the group consisting of for example cold hydrogen rich gas streams and liquid C0 2 streams.
  • the heat exchange system includes one or more external refrigerants.
  • Suitable external refrigerants may include for example include ethane, propanes, propene, ethylene, hydrochlorofluorocarbons (HCFC's), ammonia and/or mixed refrigerants; propane being the preferred external refrigerant.
  • the heat exchanger system may comprise both external and internal refrigeration.
  • the combination of internal refrigeration with both cold hydrogen rich vapour streams and liquid carbon dioxide streams together with an external refrigeration may be used.
  • the two-phase mixture including liquid carbon dioxide is preferably at a temperature of about minus 50 degrees C and a pressure greater than 60 bar, preferably greater than 80bar, 125 bar, 150 bar or 175 bar.
  • the two-phase mixture from the heat exchanger system may be passed directly to a gas-liquid separator vessel that is preferably operated at substantially the same pressure as the heat exchanger system.
  • the pressure drop across the separator vessel is typically in the range of 0.1 to 5 bar, preferably, 0.1 to 1 bar, in particular, 0.1 to 0.5 bar.
  • a high pressure gas for example a hydrogen rich gas
  • a high pressure liquid carbon dioxide stream is withdrawn from at or near the bottom of the gas-liquid separator vessel.
  • An advantage of the process of the present invention is that at least 75%, preferably, at least 90%, more preferably, at least 95% of the carbon dioxide can be separated from the gas mixture with the carbon dioxide capture level being dependent upon for example:
  • Carbon dioxide capture level generally increases with increasing pressure and reduced temperature.
  • the gas mixture is syngas
  • typically, at least 98%, preferably, at least 99%, more preferably, at least 99.5%, in particular, at least 99.8% of the hydrogen is recovered in the hydrogen rich gas stream in some examples.
  • liquid carbon dioxide can be used in some examples as an alternative, or in addition, to an external refrigerant within the separation process.
  • the temperature of the liquid carbon dioxide stream is preferably kept above a value where solid carbon dioxide will form. This typically occurs at a temperature of -56 °C (where the triple point for pure carbon dioxide is at 5.18 bar and a temperature of -56.4 C) although the presence of hydrogen may depress this freezing point.
  • the invention also provides apparatus for use in the separation of carbon dioxide from a gas mixture comprising carbon dioxide, the apparatus including:
  • a recirculation path for recirculating at least a part of the liquid carbon dioxide stream from the separator and arranged for introducing the recirculated liquid stream into a process stream.
  • the recirculation path is arranged for introducing the recirculated liquid stream into a process stream upstream of the compressor.
  • the apparatus may further include a spray device for spraying recirculated liquid carbon dioxide into a process stream.
  • the apparatus may further include a sensor for determining information relating to a parameter of the system, and a control device for controlling the recirculation of carbon dioxide on the basis of the determined information.
  • the sensor may comprise a flow rate sensor for determining information relating to the flow rate of a process stream.
  • the invention also provides apparatus for use in the separation of carbon dioxide from a feed stream comprising carbon oxide(s) the apparatus including:
  • the invention also provides apparatus for use in a system for the separation of carbon dioxide from a feed stream comprising carbon oxide(s), the apparatus including:
  • Figure 1 shows schematically the general features of an example of an arrangement in which separated liquid carbon dioxide is introduced into a process stream
  • Figure 2 shows a process flow diagram of an example having the general
  • Figure 3 shows schematically an example of apparatus for use in the introduction of liquid carbon dioxide
  • Figure 4 shows an example of a liquid carbon dioxide spray device for example for use in an apparatus shown in Figure 3.
  • the feed stream includes carbon oxide(s) and hydrogen. It will be appreciated however that other feed streams may be used in the systems and methods described.
  • a carbon oxide(s) and hydrogen feed stream may for example be generated from a solid fuel such as petroleum, coke or coal in a gasifier or from a gaseous hydrocarbon feedstock in a reformer.
  • the carbon oxide(s) and hydrogen feed stream obtained from a gasifier, or reformer may contain high amounts of carbon monoxide. Accordingly, depending on the desired composition of the hydrogen rich gas stream, the carbon oxide(s) and hydrogen feed stream may be treated in a shift converter unit where substantially all of the carbon monoxide contained in the synthesis gas stream is converted to carbon dioxide over a shift catalyst according to the water gas shift reaction (WGSR)
  • WGSR water gas shift reaction
  • the shift conversion step may be omitted, in which case the carbon oxide(s) and hydrogen feed stream comprises primarily hydrogen, carbon dioxide, carbon monoxide, and steam and minor amounts of methane.
  • the carbon oxide(s) and hydrogen feed stream is cooled to a temperature in the range of 30 to 50°C, for example, about 40°C, upstream of the compressor(s), by using a heat exchange with at least one cold process stream, which is used to condense out a predominantly water condensate.
  • the cold process stream is a process stream used during the generation of the carbon oxide(s) and hydrogen feed stream.
  • the condensate is then separated from the cooled carbon oxide(s) and hydrogen feed stream, for example, in a condensate drum.
  • the carbon oxide(s) and hydrogen feed stream that exits the gasifier will also comprise minor amounts of hydrogen sulfide (H 2 S) as an impurity (for example, sour synthesis gas).
  • H 2 S impurity is formed by the reaction of COS with steam in the shift converter unit. This H 2 S may be captured upstream of the compressor(s), for example, by selectively absorbing the 3 ⁇ 4S from the sour carbon oxide(s) and hydrogen feed stream in an absorption tower.
  • SelexolTM a mixture of dimethyl ethers of polyethylene glycol
  • Any H 2 S that is captured may either be converted into elemental sulphur, using the Claus Process, or into industrial strength sulphuric acid.
  • An alternative system for example a biological- based system, for example the Paques apparatus of Shell, may be used to remove H 2 S.
  • the sour carbon oxide(s) and hydrogen feed stream may be fed to the compressor of the present invention, where a major portion of the 3 ⁇ 4S partitions into the liquid carbon dioxide phase and may therefore be subsequently removed from the C0 2 if required, or processed and/or sequestered with the C0 2 , if required.
  • Any residual H 2 S in the final hydrogen rich gas stream may be removed downstream of the compressor by passing the final hydrogen rich gas stream through an adsorbent bed, for example, a zinc oxide bed, or by passing the final hydrogen rich vapour stream through a scrubber that utilises a suitable liquid absorbent. There is minimal pressure drop, for example, a pressure drop of less than 0.5 bar across the absorbent bed.
  • the carbon oxide(s) and hydrogen feed stream is preferably dried prior to being passed to the compressor(s), as any moisture in the synthesis gas will freeze and potentially cause blockages in the plant.
  • the carbon oxide(s) and hydrogen feed stream may be dried by being passed through a molecular sieve bed, or an absorption tower that employs a solvent, for example, triethylene glycol, to selectively absorb the water.
  • the dried carbon oxide(s) and hydrogen feed stream has a water content of less than 1 ppm (on a molar basis).
  • the dried carbon oxide(s) and hydrogen feed stream comprises at least 40 mole % hydrogen, preferably, at least 50 mole% hydrogen, in particular 55 to 60 mole % hydrogen. It may also comprise at least 30 mole % carbon dioxide, for example at least 35 mol % carbon dioxide. Even if it is not preferred, carbon monoxide can be tolerated in the carbon oxide(s) and hydrogen feed stream treated according to the present invention, e.g. if the WGSR is only partial.
  • the carbon oxide(s) and hydrogen feed stream is at a pressure in the range 1 to 12 MPa.
  • Figure 1 shows schematically the general features of an example of an arrangement in which separated liquid carbon dioxide is introduced into a process stream.
  • a feed stream 100 comprises a gas mixture including carbon oxide(s), CO( X ), and hydrogen H 2 .
  • a feed stream may be a syngas stream for example produced by a water gas shift reaction, or by other means. It will be understood that features of the present invention may be applied in relation to other feed streams, in particular other streams including carbon dioxide.
  • the feed stream 100 is first fed to a compressor 102, which pressurises the gas mixture before it is fed to a cooling device 104, where the gas mixture is cooled such that a two-phase mixture 106 is formed, including a liquid phase comprising C0 2 and a gas phase.
  • the gas phase may be hydrogen-rich, but it will be understood that the composition of the gas phase will depend on the initial composition of the gas mixture.
  • the compression and/or cooling may be carried out by a series of compressors and/or cooling devices, and may be carried out in any appropriate order. Here, the compression is carried out prior to the cooling.
  • the two-phase mixture 106 is then fed to a separation device 108 at which the mixture is separated into a separate C0 2 liquid stream 1 10 and a H 2 -rich stream 1 12.
  • the C0 2 liquid stream 110 can be removed via path 114, and/or can be recirculated, for example here via C0 2 return path 1 16 to upstream of the compressor 102.
  • the C0 2 from the C0 2 liquid stream 1 10 is passed into the feed stream 100, and the evaporation of the C0 2 liquid provides additional cooling to the system.
  • the feed flow into the compressor 102 can be maintained to a required value, even in situations where the flow of the feed into the system may be variable and/or reduced.
  • At least a portion of the H 2 -rich stream 1 12 is also
  • H 2 return path 1 18 recirculated via H 2 return path 1 18 to upstream of the compressor 102.
  • the returned C0 2 liquid stream 1 16 and returned H 2 stream are both introduced into the feed stream 100.
  • the composition of the feed stream 100 can be manipulated to for example increase the amount of H 2 and/or C0 2 in the feed stream 100, if desirable.
  • a system may be arranged so that substantially all of the 3 ⁇ 4 and C0 2 is recirculated.
  • FIG. 2 shows a process flow diagram for one example of the present invention having the general configuration of a system of Figure 1.
  • a synthesis gas stream 1 is provided as a feed stream.
  • the synthesis gas feed stream 1 contains in this example 56.9 mol% H 2 , 41.4 mol% C0 2 , 1.2 mol% CO and trace amounts of CI3 ⁇ 4, Ax and N 2 .
  • feed streams having other compositions can be used.
  • the feed stream 1 may for example be free of hydrogen sulphide or may contain hydrogen sulphide, in which case, the hydrogen sulphide will condense out of the synthesis gas feed stream together with the C0 2 as described in more detail below.
  • the system and method described can be used for the separation of C0 2 from compositions other than syngas; other gas mixtures could be used as the feed stream as appropriate.
  • a recirculated liquid C0 2 stream 78 and 3 ⁇ 4 stream 76 are introduced into the feed stream 1 as described in more detail below and provide initial cooling of the feed stream from a temperature of about 40°C to -12°C (100% Recycle) at a pressure of 73Bar.
  • the evaporation of the liquid C0 2 into the feed stream 1 provides significant cooling.
  • the resulting cooled synthesis gas steam 3 is fed to a first compressor 5 of a compression system.
  • the compression system further comprises a second compressor 11, the two compressors 5 and 11 being arranged in series.
  • Gas stream 7 exits the first compressor 5 at a pressure of 130 bar and a temperature of 32.4°C, the increase in temperature arises from heat of compression.
  • a further recirculated liquid C0 2 stream 80 is introduced into synthesis gas stream 7, giving a cooler gas stream 9 that is at a pressure of 129 bar and a temperature of 27.6°C. Gas stream 9 is then sent to the second compressor 1 1.
  • Gas stream 13 exits the second compressor 1 1 at a pressure of 175 bar and a temperature of 57.9°C before being cooled by an external coolant in a first heat exchanger 15.
  • the system is arranged such that the pressure drop across the first heat exchanger 15 is kept to a minimum, the emerging gas stream 17 being at a pressure of 174 bar and a temperature of 40.0°C.
  • the high pressure gas stream is then fed to a cooling system.
  • the cooling system includes an external heat exchanger E-105 employing an external refrigerant, for example propane and an internal heat exchanger E-106 comprising a multichannel heat exchanger employing internal process streams.
  • the compressed stream 17 is split into two substreams 17' and 17".
  • Stream 17' is cooled to form a two-phase mixture 25 across a single external heat exchanger E-105.
  • Substream 17" is passed through a multichannel heat exchanger E-106 where it is cooled against cool internal process streams including liquid C02 stream 41 as discussed below.
  • the cooled stream is combined with cooled stream 25 to form a single multi-phase stream 27.
  • the cooling arrangement of Figure 2 is given only as an example and it will be understood that other cooling arrangements are possible using external and/or internal cooling.
  • the stream may be cooled as a single stream without splitting or split into additional sub-streams, each sub-stream being cooled according to a different cooling path.
  • control of the proportion of the stream being split into each cooling path can be effected to give greater control over the cooling of the stream.
  • the resulting low temperature multiphase stream 27 comprises a liquid phase and a gaseous phase and in this example has a vapour fraction of 65.6 mol%.
  • the low temperature multiphase stream 27 is fed at a pressure of 173 bar and a temperature of -27°C to a first gas-liquid separator vessel 29.
  • a H 2 -rich gas stream 30 is withdrawn from the top of the gas-liquid separator vessel 29, while a C0 2 liquid stream 41 is withdrawn from the bottom of the gas-liquid separator vessel 29.
  • the CO2 liquid stream 41 comprises more than 97 mol% CO2 with H 2 and trace amounts of CO, CH4, Ar and N 2 .
  • the C0 2 liquid stream 41 may be of sufficient purity for export purposes.
  • further separations may be effected, for example by feeding the C02 liquid stream 41 to one or more further separators, with additional cooling being provided as necessary.
  • the resulting liquid C02 streams may be combined to form a single C02 liquid product stream.
  • C0 2 liquid stream 41 is then optionally passed through the multichannel heat exchanger E-106 to serve as an internal coolant of gas stream 17".
  • a valve 28 is provided to control the proportion of the C02 stream 1 entering the heat exchanger E-106.
  • Combined C0 2 liquid stream 74 may be at a temperature for example of 48.8°C. A part or all of the liquid C0 2 stream may then be removed from the system for subsequent use and/or storage. C0 2 liquid which is not removed, is then recirculated through the system for example as now described. At least a part of the recirculated C0 2 is preferably used as a coolant upstream.
  • the liquid C0 2 stream to be recirculated is split into two sub-streams, upstream liquid C0 2 stream 78 and downstream liquid C0 2 stream 80.
  • flow can be split as desired through the streams.
  • the splitting of the stream may be fixed, or may be variable, for example in dependence on a parameter of the system.
  • the upstream liquid C0 2 sub-stream 78 is introduced into the feed stream 1 upstream of the first compressor 5.
  • the C0 2 will be at a temperature less than that of the feed stream 1 and will therefore provide cooling.
  • the evaporation of the liquid C0 2 provides significant additional cooling compared with the introduction of gaseous C0 2 ; by using the latent heat of evaporation to provide additional cooling, heat efficiencies in the system may be achieved.
  • the downstream C0 2 sub-stream 80 is introduced into the stream downstream of the first compressor 5 and upstream of the second compressor 11. Thus further cooling is provided between the two compressors, which can remove at least a part of the heat of compression.
  • H 2 rich gas withdrawn from the separator 29 may be extracted directly from the system.
  • the H 2 rich gas stream is further managed within the system to recover temperature and/or pressure of the stream.
  • An example of such a heat and pressure management system is described in relation to Figure 2.
  • the H 2 -rich gas stream 30 may be is split into separate streams which are subject to separate processing. In the example of Figure 2, however, the hydrogen is retained as a single stream.
  • the H 2 -rich gas stream 30 is passed to an expander 44 where it is subject to expansion, thus decreasing the pressure and temperature of the stream.
  • the expander 44 preferably comprises a turbine which is used to recover work.
  • the expanded stream is then fed through a first set of channels in the multi-channel heat exchanger E-106, wherein the stream exchanges heat with other process streams, preferably by counter-flowing internal process streams in the other set of channels, in this case cooling the gas stream 17".
  • H 2 -rich gas stream 39 exits the set of channels of the multi-channel heat exchanger E-106 and is passed to a second expander 45, where it is expanded to lower pressure.
  • Stream 42 exits the expander 45 for example at a pressure of 74.0 bar and a temperature of 40°C and is passed to a further set of channels of the multi-channel heat exchanger E-106 where it exchanges heat with other internal process streams, to form 3 ⁇ 4 rich vapour stream 43.
  • the expanders may include turbines.
  • H 2 rich gas from stream 43 may then be removed from the system for storage or directly for further use.
  • the H 2 -rich gas may be passed to a Power Island (not shown) for example to be used as a component of a fuel gas feed for the combustors of a gas turbine.
  • the 3 ⁇ 4 rich gas may be combined with other components, for example may be diluted with medium pressure N 2 and/or steam.
  • At least a part of the resulting H 2 rich gas stream 76 may then be recirculated and introduced into the feed stream 1.
  • the H 2 is circulated to a region upstream of both compressors 5 and 11.
  • Recirculation of some or all of the 3 ⁇ 4 rich stream may be desirable for example on start-up or shut down of the system or at other times for example in view of system operation issues. It may be advantageous to operate the system using recirculation of the H 2 rich stream (and/or the C0 2 stream) for example during testing or demonstration procedures. Recirculation of part or all of the H 2 stream may also be used to control or vary the composition of the feed stream.
  • the recirculation of the H 2 and/or C0 2 streams is preferably controllable as discussed further below.
  • the expanders 44 and 45 may be connected to electric motors to recover energy, for example in the form of electricity.
  • the electricity may be either used in the process or exported from the process.
  • the expanders may be directly coupled to one or more of the compressors (5 and 1 1 in Figure 2). This may be effected for example by mounting the expander(s) and compressor(s) on a common shaft so that the isentropic expansion of the hydrogen rich vapour in the expander(s) is used to turn the common shaft and to drive the compressor(s). Accordingly, the net power consumption for the flow scheme of Figure 2, may be for example 24.38 MW.
  • a steam turbine ST-101 is present in this example to provide the additional power required to drive the compressors 5 and 11.
  • the system is configured such that substantially all of the gases in the system - including, as the system begins effective operation, separated H 2 rich gas and C0 2 - are recirculated via paths 76, 78 and 80 within the system.
  • the system is configured such that substantially all of the gases in the system - including, as the system begins effective operation, separated H 2 rich gas and C0 2 - are recirculated via paths 76, 78 and 80 within the system.
  • no components are exported from the system.
  • cooling path configuration can also be changed during start-up as the heat exchangers move towards their normal operating temperatures. For example, it will be seen that by diverting the flow through some or all of the various sub-stream paths described above, a selection of different preferred cooling configurations can be used as start-up proceeds.
  • H 2 rich gas and/or C0 2 can be used to optimise operation and to minimise release of unwanted components into the atmosphere.
  • H 2 rich gas and/or C0 2 may be advantageous to use the recirculation of H 2 rich gas and/or C0 2 to optimise aspects of the system, and/or as a part of the control of system parameters, for example flow rate of one or more streams in the system.
  • Various temperature controllers can be arranged in the system (TC in Figure 2).
  • the determined temperature at particular regions of the system can be used to control the amount and/or destination of recirculated streams within the system and thus the temperature of regions of the system.
  • the control on the basis of the determined temperature can be carried out for example manually or automatically, for example under computer control.
  • the flow rate of particular streams in the system can be controlled.
  • the required flow to the compressors can be maintained. This can avoid surge of the compressor.
  • FC Flow controllers
  • PC pressure controllers
  • the system further includes control apparatus for receiving information relating to one or more process parameters, for example flow rate, pressure, and controlling the location and amount of recirculated streams in the system on the basis of the received parameters.
  • a flow controller is arranged to determine the flow rate of the syngas feed stream 1. If the flow controller indicates that the flow rate has dropped below a predetermined value, the amount of C0 2 recirculated as stream 78 to upstream of the compressor 5 is increased. When the flow controller indicates that the flow rate of the feed stream has been restored to its normal value, the recirculation stream 78 can be reduced or even stopped.
  • FIG 3 shows schematically an example of apparatus for use in the introduction of liquid carbon dioxide for example in a system shown in Figure 2.
  • the apparatus includes a first evaporation device 200 and a second evaporation device 202.
  • the first evaporation device 200 is arranged upstream of the first compressor 5 and receives the feed stream 1 (which may include H 2 rich gas depending on whether the H 2 rich gas is recirculated) and also first liquid C0 2 stream 78 and outputs a cooled stream 3 which is fed directly to the compressor 5 inlet.
  • the feed stream 1 which may include H 2 rich gas depending on whether the H 2 rich gas is recirculated
  • first liquid C0 2 stream 78 which is fed directly to the compressor 5 inlet.
  • the liquid C0 2 path 204, feed stream path 206 and cooled stream path 208 are in fluid connection by means of a piping rack 210 including five connector pipes 212 which extend from the C0 2 path 204 to the cooled stream path 208, the feed stream path having fluid connection with each of the five connector pipes 212 part way between the C0 2 path 204 and cooled stream path 208.
  • a C0 2 spray nozzle 214 for spraying atomised C0 2 into the connector pipe 212.
  • recirculated liquid C0 2 from the C0 2 path 204 for example having a temperature of 40°C and a pressure of 148 bar, is injected into the compressor suction stream using the C0 2 spray nozzles 214.
  • the atomised C0 2 is then mixed with H 2 rich gas from feed path 206 having a temperature of 40°C and a pressure of 73 bar, in the piping rack 210 to give a mixed gas having a temperature of -12°C and a pressure of 73 bar.
  • the mixed gas is passed to the cooled stream path 208 and then to the compressor 5 inlet.
  • the compressed gas stream 7 is passed to the second evaporation device 202 having a similar structure to the first evaporation device 200.
  • the second evaporation device 202 is arranged upstream of the second compressor 11 and receives the pressurised stream 7 from the first compressor, and also second liquid C0 2 stream 80 and outputs a cooled stream 9 which is fed directly to the compressor 11 inlet.
  • the liquid C0 2 path 204', process stream path 206' and cooled stream path 208' are in fluid connection by means of a piping rack 210' including five connector pipes 212' which extend from the C0 2 path 204' to the cooled stream path 208' as for the first apparatus 200.
  • a C0 2 spray nozzle 214' At the base of each of the connector pipes 212' at the interface with the C0 2 path 204' is a C0 2 spray nozzle 214' for spraying atomised C0 2 into the connector pipe 212'.
  • the C0 2 liquid may be sprayed into several pipes simultaneously.
  • recirculated liquid C0 2 from the C0 2 path 204' for example having a temperature of 40°C and a pressure of 148 bar, is injected into the compressor suction stream using the C0 2 spray nozzles 214'.
  • the atomised C0 2 is then mixed with H 2 rich gas from process stream path 206' having a temperature of 28°C and a pressure of 112 bar, in the piping rack 210' to give a mixed gas having a temperature of 6°C and a pressure of 112 bar.
  • the mixed gas is passed to the cooled stream path 208' and then to the compressor 1 1 inlet.
  • FIG 4 shows schematically the C0 2 spray nozzle 214 arranged at the base of the connector pipe 212.
  • the liquid C0 2 is injected from the bottom of the connector pipe 212 as small particles 216 having a size of about 150 ⁇ by using atomisation spray nozzles.
  • the small particles 216 evaporate quickly; it is estimated that in some arrangements, the evaporation time was less than one second in view of the heat transfer coefficient in the H 2 rich gas 218 and the atomised C0 2 flow considerations.
  • the size of the pipe 212 is preferably chosen so that the C0 2 has all evaporated before the mixed gas 220 reaches the compressor inlet.
  • the piping size is chosen to give a flow velocity of about 3 m/s.
  • the length of the pipe 212 from the C0 2 path to the cooled gas path 208 is about 3 m which ensures that evaporation is complete before transfer of the mixed gas 220 to the compressor.
  • the C0 2 spray nozzle 214 may have any appropriate design.
  • the spray nozzle includes or is enhanced with a downstream piping arrangement or device that creates a turbulent flow to increase turbulence in the C0 2 liquid flow and thus facilitate thorough mixing and sufficient contact time/residence time ensuring complete evaporation.
  • the spraying, mixing and evaporation of the C0 2 can be achieved. Due to the use of a direct mixture method, evaporation can take place in a relatively simple and compact configuration. By spraying the C0 2 liquid at each compressor inlet, the overall gas temperature throughout the compression cycle can be reduced.

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Abstract

Le procédé ci-décrit sert à séparer le dioxyde de carbone d'un mélange gazeux comprenant du dioxyde de carbone. Le procédé comprend les étapes suivantes : (i) compression et refroidissement du mélange gazeux à l'aide d'un compresseur pour former un mélange biphasique contenant du dioxyde de carbone liquide ; (ii) séparation d'un flux de dioxyde de carbone liquide à partir du mélange biphasique ; et (iii) remise en circulation au moins d'une partie dudit flux de dioxyde de carbone liquide et introduction du flux liquide remis en circulation dans un flux de procédé. La remise en circulation du CO2 liquide séparé dans un flux de procédé en amont permet de refroidir ledit flux de procédé. L'utilisation du flux liquide permet d'obtenir un refroidissement supplémentaire étant donné que le refroidissement s'opère par évaporation du CO2 liquide. Par conséquent, le liquide remis en circulation peut être utilisé pour abaisser la température du flux de procédé.
EP11734170.1A 2010-07-19 2011-07-15 Séparation d'un mélange gazeux Withdrawn EP2596312A2 (fr)

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EP11734170.1A EP2596312A2 (fr) 2010-07-19 2011-07-15 Séparation d'un mélange gazeux

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EP10251287 2010-07-19
EP11734170.1A EP2596312A2 (fr) 2010-07-19 2011-07-15 Séparation d'un mélange gazeux
PCT/GB2011/001066 WO2012010819A2 (fr) 2010-07-19 2011-07-15 Séparation d'un mélange gazeux

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CN103403481A (zh) 2013-11-20
WO2012010819A3 (fr) 2014-10-23
WO2012010819A2 (fr) 2012-01-26
CN103403481B (zh) 2017-02-22
US20130118205A1 (en) 2013-05-16

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