GB2229262A - Gas processing system - Google Patents

Gas processing system Download PDF

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Publication number
GB2229262A
GB2229262A GB8905991A GB8905991A GB2229262A GB 2229262 A GB2229262 A GB 2229262A GB 8905991 A GB8905991 A GB 8905991A GB 8905991 A GB8905991 A GB 8905991A GB 2229262 A GB2229262 A GB 2229262A
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United Kingdom
Prior art keywords
stream
range
gas
psia
temperature
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GB8905991A
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GB8905991D0 (en
Inventor
Robert Hawkins Buchanan
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Amec Foster Wheeler Energy Ltd
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Foster Wheeler Energy Ltd
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Priority to GB8905991A priority Critical patent/GB2229262A/en
Publication of GB8905991D0 publication Critical patent/GB8905991D0/en
Publication of GB2229262A publication Critical patent/GB2229262A/en
Withdrawn legal-status Critical Current

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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
    • 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
    • F25J1/0032—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 the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
    • F25J1/0045—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 the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by vaporising a liquid return stream
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G5/00—Recovery of liquid hydrocarbon mixtures from gases, e.g. natural gas
    • C10G5/06—Recovery of liquid hydrocarbon mixtures from gases, e.g. natural gas by cooling or compressing
    • 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
    • F25J1/0032—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 the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
    • F25J1/004—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 the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by flash gas recovery
    • 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
    • F25J1/005—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 expansion of a gaseous refrigerant stream with extraction of work
    • 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
    • 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
    • F25J1/006—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the refrigerant fluid used
    • F25J1/007—Primary atmospheric gases, mixtures thereof
    • F25J1/0072—Nitrogen
    • 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
    • F25J1/0203—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 single-component refrigerant [SCR] fluid in a closed vapor compression cycle
    • F25J1/0205—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 single-component refrigerant [SCR] fluid in a closed vapor compression cycle as a dual level SCR refrigeration 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
    • F25J1/0203—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 single-component refrigerant [SCR] fluid in a closed vapor compression cycle
    • F25J1/0208—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 single-component refrigerant [SCR] fluid in a closed vapor compression cycle in combination with an internal quasi-closed refrigeration loop, e.g. with deep flash recycle loop
    • 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
    • F25J1/0203—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 single-component refrigerant [SCR] fluid in a closed vapor compression cycle
    • F25J1/0208—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 single-component refrigerant [SCR] fluid in a closed vapor compression cycle in combination with an internal quasi-closed refrigeration loop, e.g. with deep flash recycle loop
    • F25J1/0209—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 single-component refrigerant [SCR] fluid in a closed vapor compression cycle in combination with an internal quasi-closed refrigeration loop, e.g. with deep flash recycle loop as at least a three level refrigeration cascade
    • F25J1/021—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 single-component refrigerant [SCR] fluid in a closed vapor compression cycle in combination with an internal quasi-closed refrigeration loop, e.g. with deep flash recycle loop as at least a three level refrigeration cascade using a deep flash recycle loop
    • 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
    • F25J1/0257—Construction and layout of liquefaction equipments, e.g. valves, machines
    • F25J1/0275—Construction and layout of liquefaction equipments, e.g. valves, machines adapted for special use of the liquefaction unit, e.g. portable or transportable devices
    • F25J1/0277—Offshore use, e.g. during shipping
    • F25J1/0278—Unit being stationary, e.g. on floating barge or fixed platform
    • 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
    • F25J3/061—Natural gas or substitute 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
    • 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
    • F25J3/0635—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 CnHm with 1 carbon atom or more
    • 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
    • F25J3/064—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 CnHm with 2 carbon atoms or more
    • 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
    • F25J2205/02—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum
    • F25J2205/04—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum in the feed line, i.e. upstream of the fractionation step
    • 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
    • F25J2220/60—Separating impurities from natural gas, e.g. mercury, cyclic hydrocarbons
    • F25J2220/62—Separating low boiling components, e.g. He, H2, N2, Air
    • 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
    • F25J2220/60—Separating impurities from natural gas, e.g. mercury, cyclic hydrocarbons
    • F25J2220/64—Separating heavy hydrocarbons, e.g. NGL, LPG, C4+ hydrocarbons or heavy condensates in general
    • 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
    • F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
    • F25J2290/72—Processing device is used off-shore, e.g. on a platform or floating on a ship or barge

Abstract

A method of treating a gaseous stream from a well in the vicinity of the well head in which the feed stream, after treatment to remove water and acid gas, is subjected to the following stages: i) the feedstream at a pressure in the range 200 to 1500 psia is cooled to a temperature which is equivalent to a temperature in the range -30 DEG F to -100 DEG F at 500 psia to separate a liquid stream (A) and a gas stream (B), ii) the liquid stream (A) is expanded to form a gas stream (C) and a liquid stream (D) at a pressure in the range 15 to 125 psia and at a temperature equivalent to a temperature in the range -140 DEG F to -210 DEG F at atmospheric pressure, the liquid stream (D), which is a product NGL stream comprising a portion of the C2 component of the feedstream and substantially all the C3 heavier components of the feedstream, iii) cooling the gas stream (B) and expanding this stream to produce a liquid natural gas stream (F) at a pressure in the range 15 to 125 psia and at a temperature equivalent to a temperature in the range -240 DEG F to -270 DEG F at atmospheric pressure and optionally also a gas stream (E). <IMAGE>

Description

GAS PROCESSING SYSTEM This invention relates to the treatment of the feed stream of a gas, condensate or oil well and in particular to the treatment of the feed stream on a production platform to produce a liquid natural gas (LNG) stream and a natural gas liquid (NGL) stream which is suitable as a petrochemical feedstock. The invention is particularly suitable for an off-shore production platform but could also be used advantageously in remote on-shore areas.
The desirable characteristics for an offshore processing installation are simplicity, compactness, motion insensitivity and minimising the number of processing equipment items, and supply of make-up refrigerants and the like. In addition the processing installation must provide a product which meets the marketing needs. Thermal efficiency is of less importance off-shore due to the relatively low value of fuel gas often containing high concentrations of nitrogen which is usually available in large quantities.
It is an object of the present invention to provide a separation process for the gaseous components of a well stream which is particularly suited to off-shore installation and which will provide sparate LNG and NGL streams.
Therefore according to the present invention there is provided a method of treating a gaseous hydrocarbon containing feed stream from a well in the vicinity of the well head in which the feed stream, after treatment to remove water and acid gas, is subjected to the following stages: i) the feedstream at a pressure in the range 200 to 1500 psia is cooled to a temperature which is equivalent to a temperature in the range -30 F to -100 F at 500 psia to separate a liquid stream (A) and a gas strea'in (B), ii) the liquid stream (A) is expanded to form a gas stream (C) and a liquid stream (D) at a pressure in the range 15 to 125 psia and at a temperature equivalent to a temperature in the range -140 F to -210 F at atmospheric pressure, the liquid stream (D) comprising a major portion of the C2 component of the feedstream and substantially all the C3 and heavier components of the feedstream, iii) cooling the gas stream (B) and expanding this stream to produce a LNG stream (F) at a pressure in the range 15 to 125 psia and at a temperature equivalent to a temperature in the range -240 F to -270 F at atmospheric pressure and optionally also a gas stream (E).
References herein to a gas and/or liquid stream having a particular pressure range and being at a temperature "equivalent" to a temperature range at a designated pressure means the stream may have a temperature such that it is in a physical state equivalent to that which it would have if it were at the stated temperature range and designated pressure.
The invention provides a simple economic process for providing high recovery of NGL suitable as a petrochemical feedstock from a feed stream together with lean LNG which may be fed directly into a gas grid. The process may conveniently use compact plate-fin heat exchangers and nitrogen as a refrigerant which is advantageous from a safety aspect particularly off-shore compared to the use of mixed refrigerants such as nitrogen/methane/ethane/propane. The disadvantage of a somewhat higher refrigerant compression power requirement is more than compensated by the lower production, purification, liquefaction and transport capital of the total system and the operating cost savings compared to the conventional on-shore systems.
The invention will now be described with reference to the accompanying drawings in which: Figure 1 represents a flow diagram of a process in accordance with the invention, and, Figure 2 represents a flow diagram of a modification to the process of Figure 1.
Referring to Figure 1 the gaseous stream from a well (not shown) which is generally at a pressure within the range 200 to 1500 psia usually 200 to 1000 psia is treated to remove water, and optionally carbon oxides, hydrogen sulphide and other sulphur impurities in a conventional manner. The resulting gas stream (2) is cooled to a temperature equivalent to a temperature in the range -30 F to -100 F at 500 psia by passing through one or more heat exchangers. Figure 1 shows heat exchangers (4), (6) and (8) which may be of the plate-fin CRTM ) type. Freon4 or other types of refrigerant may be used in the higher temperature heat exchangers, optionally instead of nitrogen for pre-cooling. Nitrogen may also be used on its own as a refrigerant.The temperature of the stream (2) exiting from heat exchanger (6) is in the range -30 to -40 F and the temperature of the stream (2) exiting from heat exchanger (8) is in the range -70 to 100oF, the stream comprising at both points a mixture of liquid and gas.
The stream is then passed into a separator (10) to separate a liquid stream (A) and a gas stream (B).
Liquid stream (A) comprises substantially all of the C3 and higher components of the feed stream (2) and a major portion of the C2 component. The gas stream (B) comprises most of the C1 component of feedstream (2) and a varying portion of the C2 and higher component.
The liquid stream (A) is expanded through a Joule Thompson valve (12) to form a mixture of gas and liquid at a pressure in the range 15 to 125 psia and at a temperature equivalent to a temperature in the range -120 F to -210 F at atmospheric pressure. The pressure drop across the Joule Thompson valve (12) is generally in the range 200 to 1200 psia. The gas/liquid mixture is passed to a separator to separate a gas stream (C) and a liquid stream (D). The liquid stream (D) is NGL and comprises a substantial portion of the C2 component of the feed stream (2), typically in excess of 30% and substantially all the C3 and higher components of the feed stream (2). The content of methane in the NGL may be very low, e.g. less than 2% of the methane content of the feed stream (2).The NGL may be stored and transported in the same way as the LNG, with the same kind of tanks at the same pressure but different temperature with the boil off gas from both the LNG and NGL combined and processed together.
The gas stream (C) comprises substantially all the methane component from the stream (A) and a varying proportion of the C2 and only a minor portion of the higher components from stream (A). The low temperature of gas stream (C) may conveniently be utilised to provide cooling for gas stream (B) and/or gas stream (2).
Thereafter, the gas stream (C) may be compressed and recycled and/or used as a fuel.
Gas stream (B) is cooled to a temperature equivalent to a temperature in the range -2400F to -270 F at atmospheric pressure by passing through heat exchangers (16) and (18) using gaseous nitrogen as a refrigerant and a Joule Thompson valve (20). The pressure drop across the Joule Thompson valve (20) is generally in the range 200 to 1200 psia. The resulting stream may comprise a gas/liquid mixture which is separated in separator (22) into a gas stream (E) and LNG stream (F). The LNG stream (F) which is at a pressure in the range 15 to 125 psia may comprise at least 90 mole % methane with the balance made up of ethane and small amounts of C3 and higher components. The stream (F) may also contain minor amounts of nitrogen. Any gas stream (E) after recovering its cold is conveniently compressed and either recycled and/or use as a fuel.
The molecular balance (in mol/hr) for an exemplary process in accordance with the above process is shown in the following Table:
Component Stream (2) recycle (A) (B) (C) (D) (E) (F) N2 59.69 46.32 7.13 98.88 7.10 0.03 72.01 26.88 C1 5657.59 1157.49 1611.20 5203.86 1483.33 117.83 483.48 4720.39 C2 787.65 36.26 623.49 200.42 61.89 561.59 0.03 200.39 C3 515.65 1.04 487.90 28.79 1.77 486.13 0 28.79 iC4 60.14 0.01 59.11 1.04 0.02 59.09 0 1.05 nC4 180.14 0.01 178.17 1.94 0.02 178.15 0 1.94 iC5 24.08 0 24.00 0.08 0 24.0 0 0.08 nC5 30.77 0 30.71 0.06 0 30.71 0 0.06 C6 9.46 0 9.46 0 0 9.46 0 0 temperature 60 60 -90 -90 -184 -184 -257 -257 F pressure 530 530 510 510 17 17 17 17 psia The recycle gas is derived from streams (C) and (E) with a portion of the combined streams being used as a fuel gas.
All of the heat exchangers in Figure 1 are shown schematically as individual exchangers, however, these may be integrated in one or more exchangers with inputs and draw-offs at various points. Further, the balance between the exchangers and temperatures of operation of each exchanger can be markedly different from those indicated in the example outlined above.
It will readily be appreciated that various modifications may be made to the process of the invention depending upon the desired operating pressures and quality of the products desired without affecting the principle of the invention which is to provide a high degree of separation of LNG from the heavier components in a relatively simple, motion independent, apparatus.
For example if it is desired to produce NGL at elevated pressures the driving force in stage (ii) of the invention will be less and the amount of light ends flashed or removed from the liquid stream (A) and forced into stream (C) reduced. This disadvantage is offset by the lower overall liquefaction energy requirements, needed feed gas purity and overall cost. To realise these economies without the high cost and complexity of distillation, it may be desirable to use the heat in the gas stream (B) to heat the expanded stream (A) after expansion in valve (12) and drive off more light ends and compensate in this way with little added cost and complexity for the loss in driving force associated with the production of LNG at higher pressure.
Figure 2 of the accompanying drawings illustrates such an arrangement. The high pressure gas stream (B), for example, is further cooled in heat exchanger (26) and heats the gas liquid stream (A) after expansion from, for, example, -180 to -150 F thereby driving off light ends.
Some or all of stream (B) may by-pass heat exchanger (26) when necessary to control the C1 content in the NGL.

Claims (16)

1. A method of treating a gaseous stream from a well in the vicinity of the well head in which the feed stream, after treatment to remove water and acid gas, is subjected to the following stages: (i) the feedstream at a pressure in the range 200 to 1500 psia is cooled to a temperature which is equivalent to a temperature in the range -30 F to -100 F at 500 psia to separate a liquid stream (A) and a gas stream (B), ii) the liquid stream (A) is expanded to form a gas stream (C) and a liquid stream (D) at a pressure in the range 15 to 125 psia and at a temperature equivalent to a temperature in the range -140 F to -210 F at atmospheric pressure, the liquid stream (D), which is a product NGL stream comprising a portion of the C2 component of the feedstream and substantially all the C3 and heavier components of the feedstream, iii) cooling the gas stream (B) and expanding this stream to produce a liquid natural gas stream (F) at a pressure in the range 15 to 125 psia and at a temperature equivalent to a temperature in the range -240 F to 270"F at atmospheric pressure and optionally also a gas stream (E).
2. A method as claimed in Claim 1 in which the cooling in stage (1) is performed with conventional mechanical refrigeration.
3. A method as claimed in Claim 1 or Claim 2 in which the gas stream (C) is used to provide part of the cooling for gas stream (B).
4. A method as claimed in any preceding claim in which gas stream (C) is heated, compressed and recycled or used as a fuel.
5. A method as claimed in any preceding claim in which gas stream (E) is recycled.
6. A method as claimed in any preceding claim in which the gas stream (B) is used to heat liquid stream (D) to evaporage C1 component therefrom.
7. A method as claimed in any preceding claim in.which liquid natural gas stream (F) is at a pressure of 15 to 20 psia.
8. A method as claimed in any preceding claim in which the initial cooling in stage (i) is conducted in a plate-fin heat exchanger employing a halocarbon refrigerant.
9. A method as claimed in any preceding claim in which the cooling in stage (iii) is conducted using liquid nitrogen as refrigerant.
10. A method as claimed in any preceding claim in which the expansion of liquid stream (A) involves a pressure drop in the range 200 to 1200 psia.
11. A method as claimed in any preceding claim in which the expansion of gas stream (B) involves a pressure drop in the range 200 to 1200 psia.
12. A method as claimed in any preceding claim in which stream (F) comprises at least 95 mole % methane.
13. A method as claimed in any preceding claim in which stream (F) comprises at least 75 mole % of the methane content of the gas feed stream.
14. A method as claimed in any preceding claim in which liquid stream (D) comprises at least 30 mole % of the C2 content of the gas feed stream and at least 95 mole % of the C3 components of the gas feed stream.
15. A method as claimed in any preceding claim conducted on an off-shore installation.
16. A method as claimed in Claim 1 substantially as herein described with reference to the accompanying drawings.
GB8905991A 1989-03-15 1989-03-15 Gas processing system Withdrawn GB2229262A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2967484A1 (en) * 2010-11-16 2012-05-18 Total Sa METHOD AND SYSTEM FOR TRANSPORTING LIQUEFIED NATURAL GAS

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WO1985003116A1 (en) * 1984-01-13 1985-07-18 Union Carbide Corporation Process to separate natural gas liquids
US4718927A (en) * 1985-09-02 1988-01-12 Linde Aktiengesellschaft Process for the separation of C2+ hydrocarbons from natural gas

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1985003116A1 (en) * 1984-01-13 1985-07-18 Union Carbide Corporation Process to separate natural gas liquids
US4718927A (en) * 1985-09-02 1988-01-12 Linde Aktiengesellschaft Process for the separation of C2+ hydrocarbons from natural gas

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2967484A1 (en) * 2010-11-16 2012-05-18 Total Sa METHOD AND SYSTEM FOR TRANSPORTING LIQUEFIED NATURAL GAS
WO2012066460A2 (en) * 2010-11-16 2012-05-24 Total S.A. Method and unit for transporting liquefied natural gas
WO2012066460A3 (en) * 2010-11-16 2013-09-12 Total S.A. Method and unit for transporting liquefied natural gas

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