EP3032204A1 - Procédé et système de production d'un flux d'hydrocarbures refroidis - Google Patents

Procédé et système de production d'un flux d'hydrocarbures refroidis Download PDF

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Publication number
EP3032204A1
EP3032204A1 EP14197358.6A EP14197358A EP3032204A1 EP 3032204 A1 EP3032204 A1 EP 3032204A1 EP 14197358 A EP14197358 A EP 14197358A EP 3032204 A1 EP3032204 A1 EP 3032204A1
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EP
European Patent Office
Prior art keywords
mixed refrigerant
stream
pressure
refrigerant
target value
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.)
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EP14197358.6A
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German (de)
English (en)
Inventor
Josephus Indenkleef
Peter Marie Paulus
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Shell Internationale Research Maatschappij BV
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Shell Internationale Research Maatschappij BV
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Priority to EP14197358.6A priority Critical patent/EP3032204A1/fr
Priority to AU2015101769A priority patent/AU2015101769A4/en
Priority to NL2015933A priority patent/NL2015933B1/en
Publication of EP3032204A1 publication Critical patent/EP3032204A1/fr
Withdrawn legal-status Critical Current

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    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/0002—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the fluid to be liquefied
    • F25J1/0022—Hydrocarbons, e.g. natural 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0047—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using an "external" refrigerant stream in a closed vapor compression cycle
    • F25J1/0052—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using an "external" refrigerant stream in a closed vapor compression cycle by vaporising a liquid refrigerant stream
    • F25J1/0055—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using an "external" refrigerant stream in a closed vapor compression cycle by vaporising a liquid refrigerant stream originating from an incorporated cascade
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0211—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using a multi-component refrigerant [MCR] fluid in a closed vapor compression cycle
    • F25J1/0212—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using a multi-component refrigerant [MCR] fluid in a closed vapor compression cycle as a single flow MCR 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0244—Operation; Control and regulation; Instrumentation
    • F25J1/0245—Different modes, i.e. 'runs', of operation; Process control
    • F25J1/0249—Controlling refrigerant inventory, i.e. composition or quantity
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0244—Operation; Control and regulation; Instrumentation
    • F25J1/0252—Control strategy, e.g. advanced process control or dynamic modeling

Definitions

  • the present invention relates to a method of producing a cooled hydrocarbon stream.
  • the present invention further relates to a system for producing a cooled hydrocarbon stream.
  • a commonly used example of such a cooled hydrocarbon stream is a liquefied natural gas stream.
  • Methods and facilities for producing a cooled hydrocarbon stream, such as a liquefied natural gas stream typically comprise an automated control system to control and often optimize production of the cooled hydrocarbon stream.
  • US Patent 4,809,154 discloses an automated control system for the control of mixed refrigerant-type liquefied natural gas production facilities. With this system, functional parameters are optimized while critical operational limits are concurrently monitored and adjusted. Optimization is accomplished by adjusting parameters including mixed refrigerant (MR) inventory, composition, compression ratio, and compressor turbine speeds to achieve the highest product output value for each unit of energy consumed by the facility.
  • MR mixed refrigerant
  • the setting of the flow ratio controller valve, nitrogen content of the MR, and C3:C2 ratio is done sequentially by an algorithm which attempts to find peak efficiency while adjusting the given parameter.
  • the flow ratio controller valve is a Joule-Thomson valve (JT valve) in the MR liquid line connecting to the warm end spray header, which controls the MR liquid stream.
  • JT valve Joule-Thomson valve
  • a method of producing a cooled hydrocarbon stream comprising:
  • a system for producing a cooled hydrocarbon stream comprising:
  • Fig. 1 schematically shows an example of a method and system for producing a cooled hydrocarbon stream.
  • the presently proposed invention uses a mixed refrigerant circuit filled with an inventory of a mixed refrigerant, said mixed refrigerant consisting of a mixture of at least two different components. It is proposed to use the pressure of the mixed refrigerant in a selected point in the mixed refrigerant circuit as additional target representing an additional degree of freedom to optimize the process. This relates to the total number of molecules available in the mixed refrigerant circuit.
  • a real time optimization model is employed to calculate the pressure target value for the pressure in a selected point in the mixed refrigerant circuit.
  • the total number of molecules available in the mixed refrigerant circuit is an additional degree of freedom to be optimized.
  • the optimal number of molecules is then converted to the pressure target value.
  • the calculation is based on a plurality of measured variables including (but not limited to) temperatures and pressures in various locations in the mixed refrigerant circuit and the hydrocarbon stream conduit and quality of the vaporous refrigerant.
  • the power load is kept below a pre-determined maximum power load and while keeping the discharge temperature below a pre-determined maximum discharge temperature.
  • At least one makeup stream of one of said components is selectively fed to the mixed refrigerant circuit, and/or at least one bleed stream of refrigerant is bled from the mixed refrigerant circuit, whereby decreasing a differential between an actual pressure in said selected point and said pressure target value. Bleeding and feeding may be done simultaneously.
  • the pressure target value for the pressure in the selected point in the mixed refrigerant circuit is calculated by modeling the process using the real time optimization model based on equations of state, heat and material balances, and heat transfer rates. Once a pressure target value is known, it will be relatively straight forward to selectively feed at least one makeup stream of one of said components is to the mixed refrigerant circuit. In some cases, the pressure target value is lower than the actual pressure in which case at least one bleed stream of refrigerant may be bled from the mixed refrigerant circuit.
  • the real time optimization model is preferably a non-linear steady-state model to be able to take into account the effects of mixed refrigerant pressure.
  • the preferred real time optimization model is optimizing the non-linear balance between heat transfer efficiencies in the cryogenic heat exchanger and the compression of the vaporous refrigerant while monitoring the relevant constraints, including the effects of changing the mixed refrigerant circuit refrigerant components inventory amount.
  • the real time optimization model has a plurality of degrees of freedom represented by controlled variables, which can be used to maximize rate of production of the cooled hydrocarbon stream and/or to maximize the energy efficiency of producing the cooled hydrocarbon stream.
  • the real time optimization model calculates target values for each of these controlled variables. These target values are fed to a process control layer module, which translates the target values into manipulated variables (such as opening or closing of one or more valves) and subsequently executes the manipulated variables.
  • the mixed refrigerant typically comprises at least nitrogen, methane, C2 and C3.
  • C2 means ethane or ethylene;
  • C3 means propane, propylene, or isopropane.
  • propane propane.
  • the relative amount of nitrogen and/or C3 present in the running composition of the mixed refrigerant may be additional targets derived from one or two other additional degrees of freedom that can be calculated using the real time optimization model.
  • FIG. 1 One example of a mixed refrigerant circuit is shown in Fig. 1 .
  • the mixed refrigerant circuit 100 shown in this figure is employed to refrigerate a stream of natural gas 10 in a coil wound heat exchanger 20, whereby absorbing heat from the natural gas resulting in condensing and subcooling of the natural gas. This results in a stream of liquefied natural gas 90 being discharged from the coil wound heat exchanger 20 into a rundown line.
  • Natural gas is a valuable example of a hydrocarbon stream
  • liquefied natural gas is an example of the cooled hydrocarbon stream.
  • the mixed refrigerant circuit 100 is filled with an inventory of a mixed refrigerant, wherein the mixed refrigerant consists of a mixture of at least two different components.
  • the mixed refrigerant circuit comprises in consecutive order, a suction drum 30, a compressor train 40 in fluid connection with the suction drum 30 and downstream of the suction drum 30, a condenser 60 in fluid connection with the compressor train 40 and downstream of the compressor train 40, a pressure-reduction device 80 in fluid communication with the condenser 60 and downstream of the condenser 60, and a cryogenic heat exchanger 20 in fluid communication with the pressure-reduction device 80 and downstream of the pressure-reduction device 80.
  • the compressor train 40 forms a first boundary between a low-pressure side and a high-pressure side of the mixed refrigerant circuit 100
  • the pressure-reduction device 80 forms a second boundary between the high-pressure side and the low-pressure side.
  • the mixed refrigerant is circulated as a mixed refrigerant stream through the mixed refrigerant circuit.
  • the mixed refrigerant circuit 100 is cyclic. Describing one cycle, the refrigerant passes in vaporous condition to the compressor train 40.
  • the vaporous refrigerant passes through the compressor train 40 from the low-pressure side to the high-pressure side, whereby increasing a pressure of the vaporous refrigerant in accordance with a compression ratio.
  • the vaporous refrigerant passes through the suction drum 30 prior to feeding to the compressor train 40, to ensure that the vaporous refrigerant stream is free from any liquid.
  • the compressor train 40 can comprise one compressor or a number of compressors operating in series (wherein a discharge stream from one of the compressors in the train is fed as input to a next compressor in the train), or in parallel wherein vaporous refrigerant is divided over two or more parallel arranged compressors.
  • the one compressor, any of multiple compressors may comprise a plurality of stages.
  • the compressor train 40 as shown in Fig. 1 by way of example is drawn in as a first stage compressor 41 arranged in series with a second stage compressor 42.
  • the vaporous refrigerant stream passes from the first stage compressor 41 to the second stage compressor 42 through an optional inter-stage cooler 44. More stages can be added depending on the desired compression ratio.
  • the compressor train 40 may also be arranged as a single compressor having at least two stages, with or without inter-stage cooling.
  • the vaporous refrigerant passes at least through the condenser 60, wherein the compressed vapour is at least partially condensed.
  • the vaporous refrigerant passes from the compressor train 40 to the condenser 60 though one or more other heat exchangers acting as de-superheaters. This is particularly useful if the other heat exchangers are arranged to pass heat from the vaporous refrigerant stream to an ambient stream such as air or water being fed to the heat exchanger at an ambient temperature.
  • the vaporous refrigerant passes from the compressor train 40 to the condenser 60 though an air cooler 50. In such a case, the condenser 60 could be refrigerated to reduce the temperature of the refrigerant stream to below the ambient temperature.
  • the pressure-reduction device comprises a first JT valve which in the case of Fig. 1 is embodied in the form of an HMR JT valve 75, and a second JT valve which in the case of Fig. 1 is embodied in the form of an LMR JT valve 85.
  • JT valve stands for Joule-Thomson valve.
  • Other types of pressure reduction devices, including turbines, may be employed instead of a JT valve or in combination with a JT valve.
  • the refrigerant stream is partly condensed in the condenser 60 forming a condensed fraction and a vapor fraction, whereby the refrigerant stream consisting of those condensed and vapor fractions passes through a phase separator 70 as it passes from the condenser 60 to the pressure-reduction device.
  • the phase separator 70 the condensed fraction is separated from the vapor fraction, and discharged as LMR stream 82.
  • LMR stands for "light mixed refrigerant”.
  • the condensed fraction is discharged from the phase separator 70 as HMR stream 72.
  • HMR stands for "heavy mixed refrigerant". In this context the terms "light” and “heavy” are used in a relative sense to indicate that the LMR has a lower average molecular weight than the HMR or, conversely, that the HMR has a higher average molecular weight than the LMR.
  • Both the HMR stream and the LMR stream are further cooled in the coil wound heat exchanger 20, whereby the HMR stream 72 is subcooled and the LMR stream 82 is condensed and subsequently subcooled before being passed respectively to the HMR JT valve 75 and the LMR JT valve 85.
  • the HMR JT valve 75 and the LMR JT valve 85 are set in respective valve positions to impose a selected flow rate ratio between the heavy mixed refrigerant stream and the light mixed refrigerant stream. It is stressed here, that not all processes in which the invention is envisaged employ two distinct refrigerant streams such as the HRM and LMR streams and/or two distinct pressure reduction devices as presently shown in the example of Fig. 1 .
  • the refrigerant stream (in the case of Fig. 1 the LMR stream and the HMR stream) are passed to the cryogenic heat exchanger 20, wherein the mixed refrigerant stream is allowed to evaporate.
  • the refrigerant is then discharged from the cryogenic heat exchanger 20 and subsequently passed to the compressor train 40 through the suction drum 30 whereby completing one single pass of the refrigerant stream through the mixed refrigerant circuit 100.
  • upstream and downstream "prior to” and “subsequent” in the context of the refrigerant passing through the mixed refrigerant circuit 100 are used assuming a single pass through the mixed refrigerant circuit 100 starting and ending in the suction drum 30.
  • the stream of natural gas 10 passes through the cryogenic heat exchanger 20 as well, through a hydrocarbon stream conduit in said cryogenic heat exchanger 20.
  • the stream of natural gas 10 passes through the cryogenic heat exchanger 20 in indirect heat exchanging contact with the evaporating refrigerant, whereby heat passes from the stream of natural gas 10 to the evaporating refrigerant.
  • the stream of natural gas 10 is cooled, thereby forming the cooled hydrocarbon stream which in the case of the example of Fig. 1 is the stream of liquefied natural gas 90.
  • the cooled hydrocarbon stream is discharged from the cryogenic heat exchanger at a discharge temperature.
  • the discharge temperature can be determined using a discharge temperature sensor 95.
  • the refrigeration is powered by a driver 48, driving the compressor train 40 at a power load.
  • the mixed refrigerant circuit 100 further comprises a pressure sensor 78 sensing an actual pressure of the mixed refrigerant in a selected point in the mixed refrigerant circuit 100.
  • the selected point may be in the high-pressure side of the mixed refrigerant circuit 100.
  • the pressure sensor 78 senses the actual pressure in the phase separator 70. Nonetheless, in another set of embodiments the selected point may be in the low-pressure side of the mixed refrigerant circuit 100.
  • the pressure sensor could be arranged such as to sense the actual pressure in the suction drum 30 (instead of the phase separator 70).
  • the mixed refrigerant circuit 100 comprises a quality measurement instrument (QMI) 45 in fluid communication with the vaporous refrigerant.
  • the QMI is arranged to determine a circulating composition of the mixed refrigerant.
  • Various types of suitable QMIs are known in the art.
  • the QMI 45 is arranged to measure the circulating composition between the inter-stage cooler 44 and the second stage compressor 42. However, it may be positioned elsewhere if desired, such as in a refrigerant discharge line 25 extending between the cryogenic heat exchanger 20 and the suction drum 30, or downstream of the compressor train 40 while upstream of the condenser 60.
  • the system of Fig. 1 comprises a makeup line 12 for selectively feeding at least one makeup stream of one of the refrigerant components to the mixed refrigerant circuit 100.
  • the system also comprises a bleed line for bleeding at least one bleed stream of refrigerant from the mixed refrigerant circuit.
  • the bleed line may connect to the mixed refrigerant circuit in any suitable point. Generally, it is preferred to connect the bleed line to the mixed refrigerant circuit in a point where vapour free liquid can be bled from the refrigerant circuit.
  • two bleed lines are employed: an HMR bleed line 22 and an LMR bleed line 32. Both the HMR bleed line 22 and an LMR bleed line 32 connect to the mixed refrigerant circuit in a point where vapour free liquid can be bled from the refrigerant circuit.
  • the system further comprises a control unit 200.
  • the control unit 200 comprises a real time optimizer and a process control layer module.
  • the real time optimizer has a plurality of degrees of freedom which can be converted to controlled variables. These controlled variables can be used to maximize rate of production of the liquefied natural gas and/or to maximize the energy efficiency of producing the liquefied natural gas.
  • the real time optimizer is programmed with a real time optimization model that calculates target values for each of these controlled variables based on a number of measured variables. These target values are fed to a process control layer module, which translates the target values into manipulated variables (such as opening or closing of one or more valves) and subsequently executes the manipulated variables.
  • the real time optimizer calculates a pressure target value for the pressure in the selected point in the mixed refrigerant circuit, using the real time optimization model.
  • Input to the real time optimization model are a plurality of measured variables including flow rates, temperatures, and pressures, in various locations in the mixed refrigerant circuit and the hydrocarbon stream conduit and quality of the vaporous refrigerant.
  • the power load is kept below a pre-determined maximum power load and the discharge temperature is kept below a pre-determined maximum discharge temperature - these are part of the constraints taken into account by the real time optimization model.
  • the plurality of measured variables may comprise flow rate of the cooled hydrocarbon stream, flow rates of the mixed refrigerant, compressor load, and the individual MR inventories as primary degrees of freedom, while all plant measurements (including the mixed refrigerant QMI) are used to determine mismatch between plant and model, and to determine model base performance.
  • the control unit 200 will selectively manipulate a feed valve 210 and/or a bleed valve (such as an HMR bleed valve 220 and/or an LMR bleed valve 230) to selectively feed at least one makeup stream of one of the refrigerant components to the mixed refrigerant circuit 100 and/or bleed at least one bleed stream of refrigerant from the mixed refrigerant circuit 100.
  • a feed valve 210 and/or a bleed valve such as an HMR bleed valve 220 and/or an LMR bleed valve 230
  • a differential between the actual pressure in the selected point for instance as measured in pressure sensor 78
  • Which feed valve and/or bleed valve to manipulate may be determined depending on desired values or ranges of the vaporous refrigerant QMI.
  • a selected flow rate ratio between the heavy mixed refrigerant stream and the light mixed refrigerant stream is imposed by the settings of the first JT valve and the second JT valve.
  • a composition ratio between the methane and C2 in the mixed refrigerant is regulated to accommodate to the selected flow rate ratio being imposed.
  • the degree of condensation in the condenser 60 is governed predominantly by the composition ratio between the methane and C2.
  • the methane and C2 contents in the mixed refrigerant are therefore not derived from degrees of freedom available to the real time optimizer.
  • the real time optimizer does have degrees of freedom to set targets for the nitrogen content and/or the C3 content in the vaporous refrigerant.
  • the nitrogen target is set for the nitrogen content in the LMR stream 82 and/or the C3 target is set for the C3 content in the HMR stream 72.
  • a nitrogen target value and/or a C3 target value is also calculated using the real time optimization model (in addition to the pressure target value), wherein the nitrogen target value corresponds to the relative amount of nitrogen in the vaporous refrigerant or the LMR stream, and the C3 target value corresponds to a relative amount of C3 in the vaporous refrigerant or the HMR stream.
  • the amount of nitrogen in the mixed refrigerant predominantly determines the bubble point at the cold end of the cryogenic heat exchanger.
  • the nitrogen target value is strongly dependent on the desired discharge temperature and the desired cold end approach temperature of the cryogenic heat exchanger which impacts the efficiency.
  • the amount of C3 in the mixed refrigerant predominantly can be used to optimize the cooling curve in the part of the cryogenic heat exchanger where the largest heat transfer takes place.
  • the C3 target value influences for instance the superheat temperature at the warm end of the cryogenic heat exchanger.
  • the selectively feeding and/or bleeding preferably comprises changing the relative amounts of nitrogen and/or C3 whereby decreasing a differential between an actual nitrogen or C3 content in the vaporous refrigerant and said nitrogen target value or C3 target value.
  • the actual nitrogen and/or C3 contents are determined by the QMI 45 and provided to the real time optimizer to be used as input for the real time optimization model. If the nitrogen and C3 targets refer to the nitrogen and C3 content in the LMR stream and HMR stream, the values as determined by the QMI 45 may simply be converted to nitrogen content in the LMR stream and C3 content in the HMR stream, for instance using a standard flash calculation. Alternatively, specific an LMR QMI and an HRM QMI may be provided to measure the nitrogen and C3 contents in respectively the LMR stream 82 and the HMR stream 72.
  • nitrogen can be selectively bled from the mixed refrigerant circuit via the LMR bleed line 32 by opening the LMR bleed valve 230 while simultaneously feeding methane into the mixed refrigerant circuit 100 to compensate for the loss of methane through the LMR bleed line 32.
  • C3 can be selectively bled from the mixed refrigerant circuit via the LMR bleed line 22 by opening the HMR bleed valve 220 while simultaneously feeding C2 into the mixed refrigerant circuit 100 to compensate for the loss of C2 through the HMR bleed line 22.
  • both the LMR bleed valve 220 and LMR bleed valve 230 can be opened simultaneously to retain the composition.
  • the invention can be used in other types of mixed refrigerant circuits, for cooling natural gas or other types of hydrocarbon streams.
  • Other types of mixed refrigerant circuits may for instance employ a different type of heat exchanger instead of the coil would heat exchanger 20.
  • Any suitable process or liquefaction system wherein a cryogenic heat exchanger is employed may be used in combination with the presently proposed invention.
  • suitable liquefaction systems may employ single refrigerant cycle processes (usually single mixed refrigerant - SMR - processes, such as PRICO described in the paper "LNG Production on floating platforms” by K R Johnsen and P Christiansen, presented at Gastech 1998 (Dubai); double refrigerant cycle processes (for instance the much applied Propane-Mixed-Refrigerant process, often abbreviated C3MR, such as described in for instance US Patent 4,404,008 , or for instance double mixed refrigerant - DMR - processes of which an example is described in US Patent 6,658,891 .
  • single refrigerant cycle processes usually single mixed refrigerant - SMR - processes, such as PRICO described in the paper "LNG Production on floating platforms" by K R Johnsen and P Christiansen, presented at Gastech 1998 (Dubai); double refrigerant cycle processes (for instance the much applied Propane-Mixed-Refrigerant process, often abbreviated C3MR, such as described in
  • the invention has been described with particular reference to a mixed refrigerant circuit.
  • Some of the suitable processes or liquefaction systems referred to in the previous paragraphs make use of a pre-cooling mixed refrigerant circuit and a main mixed refrigerant circuit in cascaded relationship with the pre-cooing mixed refrigerant circuit.
  • the Shell DMR process is an example thereof. While it is preferred that the real time optimizer and real time optimizing model as proposed herein is employed to optimize the main mixed refrigerant circuit, is contemplated that a similar real time optimizer and real time optimizing model as described herein can be employed to a pre-cooling mixed refrigerant circuit.
  • the hydrocarbon stream may be obtained from natural gas or petroleum reservoirs or coal beds.
  • the hydrocarbon stream may also be obtained from another source, including as an example a synthetic source such as a Fischer-Tropsch process, or from a mix of different sources.
  • a synthetic source such as a Fischer-Tropsch process
  • the hydrocarbon stream comprise at least 50 mol% methane, more preferably at least 80 mol% methane.
  • the hydrocarbon stream may contain varying amounts of components other than methane and nitrogen, including one or more non-hydrocarbon components other than water, such as CO 2 , Hg, H 2 S and other sulphur compounds; and one or more hydrocarbons heavier than methane such as in particular ethane, propane and butanes, and, possibly lesser amounts of pentanes and aromatic hydrocarbons.
  • one or more non-hydrocarbon components other than water such as CO 2 , Hg, H 2 S and other sulphur compounds
  • hydrocarbons heavier than methane such as in particular ethane, propane and butanes, and, possibly lesser amounts of pentanes and aromatic hydrocarbons.
  • the hydrocarbon stream may have been pretreated to reduce and/or remove one or more of undesired components such as CO 2 and H 2 S, or have undergone other steps such as pre-pressurizing or the like. Such steps are well known to the person skilled in the art, and their mechanisms are not further discussed here.
  • the ultimate composition of the hydrocarbon stream thus varies depending upon the type and location of the gas and the applied pre-treatment(s).

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EP14197358.6A 2014-12-11 2014-12-11 Procédé et système de production d'un flux d'hydrocarbures refroidis Withdrawn EP3032204A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP14197358.6A EP3032204A1 (fr) 2014-12-11 2014-12-11 Procédé et système de production d'un flux d'hydrocarbures refroidis
AU2015101769A AU2015101769A4 (en) 2014-12-11 2015-12-09 Method and system for producing a cooled hydrocarbons stream
NL2015933A NL2015933B1 (en) 2014-12-11 2015-12-10 Method and system for producing a cooled hydrocarbons stream.

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EP14197358.6A EP3032204A1 (fr) 2014-12-11 2014-12-11 Procédé et système de production d'un flux d'hydrocarbures refroidis

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EP3032204A1 true EP3032204A1 (fr) 2016-06-15

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AU (1) AU2015101769A4 (fr)
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IT202200009698A1 (it) * 2022-05-11 2023-11-11 Nuovo Pignone Tecnologie Srl Method for determining the quantity of refrigerant fluid which has to be inject-ed into a thermodynamic system of a liquefied natural gas plant

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EP3351881A1 (fr) * 2017-01-24 2018-07-25 GE Oil & Gas, LLC Optimisation de réfrigérant mélangé en continu pour la production de gaz naturel liquéfié (gnl)
CN108344251A (zh) * 2017-01-24 2018-07-31 通用电气石油和天然气有限责任公司 用于液化天然气(lng)的生产的连续混合制冷剂优化
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IT202200009698A1 (it) * 2022-05-11 2023-11-11 Nuovo Pignone Tecnologie Srl Method for determining the quantity of refrigerant fluid which has to be inject-ed into a thermodynamic system of a liquefied natural gas plant

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