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
  • F25J1/02—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
• • 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
• • 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
  • F25J1/0025—Boil-off gases "BOG" from storages
• • 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
  • F25J1/006—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
  • F25J1/0204—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 single flow SCR 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
  • F25J1/0279—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc.
  • F25J1/0285—Combination of different types of drivers mechanically coupled to the same refrigerant compressor, possibly split on multiple compressor casings
  • F25J1/0288—Combination of different types of drivers mechanically coupled to the same refrigerant compressor, possibly split on multiple compressor casings using work extraction by mechanical coupling of compression and expansion of the refrigerant, so-called companders
• • 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
  • F25J2230/04—Compressor cooling arrangement, e.g. inter- or after-stage cooling or condensate removal
• • 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
  • F25J2230/08—Cold compressor, i.e. suction of the gas at cryogenic temperature and generally without afterstage-cooler
• • 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
  • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
  • F25J2230/60—Processes or apparatus involving steps for increasing the pressure of gaseous process streams the fluid being hydrocarbons or a mixture of hydrocarbons
• • 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
  • F25J2270/14—External refrigeration with work-producing gas expansion loop
  • F25J2270/16—External refrigeration with work-producing gas expansion loop with mutliple gas expansion loops of the same refrigerant
• • 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
  • F25J2290/10—Mathematical formulae, modeling, plot or curves; Design methods

Definitions

• the invention relates to the field of re-liquefaction of boil-off gases from liquid natural gas (LNG). More specifically, the invention relates to a method and system for cooling a boil-off gas stream, as set out in the introduction to the independent claim 1.
• LNG liquid natural gas
• a common technique for transporting natural gas from its extraction site is to liquefy the natural gas at or near this site, and transport the LNG to the market in specially designed storage tanks, often placed aboard a sea-going vessel.
• the process of liquefying the natural gas involves compression and cooling of the gas to cryogenic temperatures (e.g. -160 0 C).
• cryogenic temperatures e.g. -160 0 C.
• the LNG carrier may thus transport a significant amount of liquefied gas to its destination.
• the LNG is offloaded to special tanks onshore, before it is either transported by road or rail on LNG carrying vehicles or re-vaporized and transported by e.g. pipelines.
• the Moss RSTM Concept is based on a closed nitrogen expansion cycle, extracting heat from the boil-off gas.
• Boil-off gas (BOG) is removed from the cargo tanks by two conventional LD compressors operating in series.
• the BOG is cooled and condensed to LNG in a cryogenic heat exchanger ("cold box"), to a temperature between the saturation temperature for compressed CH 4 and N 2 before being fed into a separator vessel where certain non-condensibles (mainly N 2 ) is removed.
• the LNG coming out of the separator is pumped back to the cargo tanks, while the non-condensibles (i.e. gases) are sent to a flare or vent stack.
• the present Moss RSTM concept is based on a nitrogen Brayton cycle with three-stage compression and one-stage expansion. Using only one expander reduces the complexity of the compander-unit (compressors and expander) to a minimum, but the internal temperature approach between hot and cold streams is inadequately large in the middle sec- tions of the cold-box. This is shown in Figure 1. As the rather large area between the hot and cold composite curves represent a plain exergy loss, process innovations are sought in order to minimize this area.
• exergy losses can be reduced through the introduction of an additional expander.
• a recognized method for implementing such a unit is to split the refrigerant stream at a given temperature level and hence let two expanders work in parallel as described in Norwegian patent application 2004 0306.
• the present invention meets that need, in that it provides a method for cooling a boil-off gas (BOG) stream prior to compression in a boil-off reliquef action plant where the BOG stream following compression is reliquefied in heat exchange with a closed-loop refrigeration system comprising a coolant being compressed, before said reliquefied BOG being returned to a storage vessel, characterized by the following steps:
• the invention also provides a system for cooling a boil-off gas (BOG) stream prior to compression in a boil-off reliquefaction plant, comprising a line for feeding BOG into a compressor prior to heat exchange with a closed-loop refrigeration system, said refrigeration system comprising compressors and expanders and a number of heat exchangers for heat exchange with the BOG stream, characterized in that the expanders are arranged in series.
• BOG boil-off gas
• Figure 1 shows a composite curve for the known one-expander Moss RSTM concept.
• Figure 2 is a principle flow diagram showing the Nitrogen Brayton cycle with two expanders in series, according to the invention.
• Figure 3 shows a composite curve for the nitrogen Brayton cycle with two expanders in series, (cf. Figure 2).
• Figure 4 is a principle flow diagram illustrating the Nitrogen Brayton process with two expanders in series and nitrogen precooling according to the invention.
• Figure 5 shows a composite curve for the nitrogen Brayton cycle with the process ac- cording to the invention (cf. Figure 4).
• Figure 6 is a principle flow diagram of an embodiment of the invention, illustrating pre- and intercooling LD compressor with parallel split streams.
• Figure 7 is a principle flow diagram of an embodiment of the invention, illustrating pre- and intercooling LD compressor with split stream in series.
• Figure 8 is a principle flow diagram of an embodiment of the invention, showing points for pre- and intercooling with intermediate-pressure nitrogen.
• the BOG is in most cases precooled before compression (by the compressor 11) prior to the cold-box. This is done in order to ensure a reasonable temperature profile in the cold-box and to achieve a more efficient compression in a reasonably sized LD- compressor-unit 11.
• precooling has been described in several other patents, involving methods such as
• the boil-off gas stream 10 from a reservoir (not shown) is compressed in a regular fashion in the compressor 11.
• the boil-off stream 12 is thus routed through a compact heat exchanger (visualized in the figures as four separate heat exchangers) 5, 6, 7, 7b and heat exchanged against the closed-loop refrigeration system as will be described below.
• the stream 13 exiting the heat exchanger (or series of heat exchangers) is completely re-liquefied with a careful tuning of the refrigeration system.
• the person skilled in the art will appreciate that the heat exchangers 5, 6, 7, 7b as shown in the figures, may be combined into one compact heat exchanger.
• FIG 4 shows a compressor system comprising three in-line compressors 2, 3, 4.
• the compression may be achieved by one compression unit comprising three compressor wheels and two expander wheels connected via a common gear box.
• the compressor system compresses the coolant (refrigerant), e.g. nitrogen, and feeds this stream 15 into the first heat ex- changer stage 5 where it is heat exchanged against the return coolant stream 20.
• the coolant stream 16 is expanded in the expander 8 before being heat exchanged (stream 17) in the second heat exchanger 6 against the return coolant stream 20.
• the heat exchanged stream 17B is the heat exchanged in the third heat exchanger 7, before the stream 18 is expanded in the expander 9.
• the expanded coolant stream 19 is then heat exchanged in the fourth heat exchanger 7b, then routed (line 20) back to the compressor system 2, 3, 4 through the heat exchangers 7, 6, 5.
• a BOG precooler 30 is included in the BOG feed line 10, upstream of the compressor 11.
• the line 33 feeds a fraction of the coolant (e.g. nitrogen) from a take-off point on the return coolant stream 20 between the second 6 and third 7 heat exchanger stage to the precooler 30, and the (heat exchanged) coolant is returned to the return coolant stream 20 via line 32, at an entry point downstream of said take-off point.
• the coolant e.g. nitrogen
• the BOG flow rate through the cold-box is under normal operation modes kept at the absolute minimum. When no recycling of the LD-compressor is needed only direct boil-off from the cargo tanks are processed in the reliquefaction sys- tern.
• the refrigerant (or coolant, e.g. nitrogen) flow rate through the low-temperature sections of the cold-box is the same as that running through the 3 nitrogen compressors 2, 3, 4, i.e. the maximum.
• the fraction of the low-pressure nitrogen taken out from the cold-box can be de- signed with an optimal temperature, ensuring minimal exergy losses in the precooler 30. 4. Taking out some of the low-pressure refrigerant (e.g. nitrogen) will result in a better match for the cold-box' composite curves (i.e. reduced exergy losses) as this will reduce the local temperature approach in an area where this approach is generally large (ref. Figure 5).
• some of the low-pressure refrigerant e.g. nitrogen
• Another effect of splitting the low-pressure refrigerant stream is that it can be used, not only to precool the boil-off gas to the LD-compressor 30, but also to intercool the BOG between the two LD-compressor stages.
• choosing such a solution offers more flexibility to adjust the temperature of the BOG entering the cold-box. This will, for different operational modes, reduce thermal stresses in the plate-fin heat exchanger, and open the possibility for reducing power under various operating conditions such as ballast voyages and voyages with nitrogen-rich LNG cargos.
• FIG. 6 a preferred embodiment and a flexible solution for integrating both precoolers and intercoolers is shown in figure 6.
• two splits ensure that the BOG temperature can be cooled down to the same low temperature in both the precooler 30' and the inter- cooler 30".
• a BOG precooler 30' is included in the BOG feed line 10, upstream of the first compressor 11', while the BOG intercooler 30" is included in the BOG feed line downstream of the first compressor 11" and upstream of the second compressor 11'.
• the lines 33', 33" feed a part of the coolant (e.g.
• the coolant is fed from the similar take-off point in the return line 20 as described above via line 37 to the precooler 30', then via line 36 from the precooler 30' to the intercooler 30", before it is returned to the cold-box via line 38.
• This embodiment is only possible when higher temperatures are allowed in the intercooler compared to the aftercooler. It is, however, possible to reach intercooler temperature levels close to those of the precooler, but this implies a high nitrogen flow rate, and hence high pre- and intercooling exergy losses.
• An alternative solution is to feed the cold nitrogen stream to the precooler from the intermediate-pressure nitrogen stream between the two expansion stages.
• This can in principle be done at any point between the two expanders, shown as points A, B, and C in Figure 8.
• points A, B, and C In point A, the local temperature approach is small, and the nitrogen flow rate might be slightly increased as a consequence of this, but points A and C will on the other hand make the plate-fin heat exchanger design somewhat less complicated than point B.
• the most suitable of the three points will be chosen as a result of economical considerations, control procedures, and energy demand of different LNG cargo compositions. For the already discussed two-expander solution, this will ensure that some of the expansion work is utilized for the nitrogen stream that is redirected to the precooler.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Ocean & Marine Engineering (AREA)
• Filling Or Discharging Of Gas Storage Vessels (AREA)

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Cited By (4)

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Citations (5)

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• 2005
  • 2005-03-14 NO NO20051315A patent/NO20051315L/no not_active Application Discontinuation
• 2006
  • 2006-03-08 EP EP06716763.5A patent/EP1861670A4/en not_active Withdrawn
  • 2006-03-08 US US11/817,825 patent/US20080202158A1/en not_active Abandoned
  • 2006-03-08 KR KR1020077023447A patent/KR101194474B1/ko active IP Right Grant
  • 2006-03-08 CN CNA2006800080739A patent/CN101137878A/zh active Pending
  • 2006-03-08 WO PCT/NO2006/000090 patent/WO2006098630A1/en active Application Filing

Patent Citations (5)

Non-Patent Citations (1)

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