CN104792115A - Heavy hydrocarbon recycling system and technology for LNG-FPSO - Google Patents
Heavy hydrocarbon recycling system and technology for LNG-FPSO Download PDFInfo
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- CN104792115A CN104792115A CN201510212249.3A CN201510212249A CN104792115A CN 104792115 A CN104792115 A CN 104792115A CN 201510212249 A CN201510212249 A CN 201510212249A CN 104792115 A CN104792115 A CN 104792115A
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Abstract
The invention relates to a heavy hydrocarbon recycling system and technology for an LNG-FPSO. The heavy hydrocarbon recycling system is characterized by comprising a cold box, a precooling system and a heavy hydrocarbon separating system. Three-level refrigerating is adopted in the precooling system for providing cold for natural gas and LPG processing in the heavy hydrocarbon separating system. By means of the technology, cold of a precooling unit can be fully utilized, the pressure energy of the high-pressure natural gas is utilized, heavy hydrocarbon in the natural gas is fully recycled, the propane recycling rate is increased, and good economical efficiency is achieved. A natural gas expansion machine in the heavy hydrocarbon separating system is directly connected with a deethanizing column, the device is compact and simple, the number of procedures and the number of valves are small, installation is facilitated, and the heavy hydrocarbon recycling system and technology are applied to offshore operation very easily. The recycling system can be widely applied to the heavy hydrocarbon recycling technology for the LNG-FPSO in the ocean production environment.
Description
Technical field
The present invention relates to a kind of heavy hydrocarbon recovery system and technique, be particularly used for heavy hydrocarbon recovery system and the technique of LNG-FPSO (LNG FPSO for Marginal Gas Fields Development) about one.
Background technology
China coastal seas natural gas proved reserves are enriched, but quite a few is gas field, deep-sea, marginal gas field and low grade natural gas resource.For the exploitation of this type of source of the gas, adopt the mode such as traditional ocean platform and seabed relation then can be subject to the restriction of cost and technology, therefore adopt LNG-FPSO, both can flexible configuration, the needs of natural gas extraction can be met again.LNG-FPSO has is convenient to migration, reusable, production efficiency advantages of higher, and this, to promotion China marine site especially gas field, deep-sea, small gas fields exploitation, makes full use of petroleum resources significant.
Liquefaction process is one of core technology of LNG-FPSO, meet safety, flow process is simple, strong adaptability, start-stop car are rapid and automaticity high.As the important step in liquefaction process, the following content of the general demand fulfillment of heavy hydrocarbon recovery process: the natural gas after (1) de-heavy hydrocarbon before entering liquefaction unit wherein C6+ (components more than 6 carbon hydrocarbon) constituent content meet liquefaction process requirement; (2) process runs well, fluctuation is little; (3) to the strong adaptability of different source of the gas; (4) as far as possible many recovery heavy hydrocarbons, to improve the economy of device; (5) technique is simple, and equipment is as far as possible few, and floor space is little; (6) safe and reliable.Before natural gas liquefaction, must heavy hydrocarbon be removed, otherwise, may freeze and occluding device in liquefaction process.Land liquefaction factory generally adopts the way of distillation to remove heavy hydrocarbon in pretreating process, adopts dethanizer and liquefied gas tower production fluid in next life liquefied oil gas, remains a small amount of heavy hydrocarbon and is separated removal at low-temperature space.And land technological process is complicated, floor space is installed greatly and not easily, marine applicability is poor.Land existing heavy hydrocarbon recovery process generally can not be directly used in LNG-FPSO, needs to study a kind of new technology being applicable to marine environment.
Summary of the invention
For the problems referred to above, the object of this invention is to provide a kind of the heavy hydrocarbon recovery system for LNG-FPSO and technique that utilize the cold of chilldown system and natural gas self to expand to lower the temperature and combine.
For achieving the above object, the present invention takes following technical scheme: a kind of heavy hydrocarbon recovery system for LNG-FPSO, is characterized in that: it comprises an ice chest, a chilldown system and a heavy hydrocarbon piece-rate system, six pipelines for heat exchange are provided with in described ice chest, described chilldown system comprises a low pressure separator, the entrance of described low pressure separator is connected the two ends of the 3rd pipeline in described ice chest with liquid-phase outlet, the gaseous phase outlet of described low pressure separator connects one first compressor, one first blender, one second compressor, one second blender, one the 3rd compressor, a water cooler, a first throttle valve and a high-pressure separator successively, the gaseous phase outlet of described high-pressure separator connects the gas phase entrance of described second blender, and the liquid-phase outlet of described high-pressure separator connects one first current divider, first outlet of described first current divider connects the entrance of described high-pressure separator by the first pipeline in described ice chest, and the second outlet of described first current divider connects a MP separator by a second throttle, the gaseous phase outlet of described MP separator connects the gas phase entrance of described first blender, and the liquid-phase outlet of described MP separator connects one second current divider, first outlet of described second current divider connects the entrance of described MP separator by the second pipeline in described ice chest, and the second outlet of described second current divider connects the entrance of described low pressure separator by one the 3rd choke valve, in described ice chest, the entrance of the 6th pipeline connects gas pipeline, exports the gas-liquid separator, a Natural gas expander and the dethanizer that connect successively in described heavy hydrocarbon piece-rate system, the liquid-phase outlet of described gas-liquid separator is connected the upper entrance of described dethanizer by one the 6th choke valve and the 4th pipeline in described ice chest, the gaseous phase outlet of described dethanizer connects fuel gas for station, the liquid-phase outlet of described dethanizer connects the upper entrance of a debutanizing tower by one the 4th choke valve, the gaseous phase outlet of described debutanizing tower connects a condenser, the exit end of described condenser connects back described debutanizing tower, the other end is connected a liquefied petroleum gas storage tank by the 5th pipeline in described ice chest with one the 7th choke valve, the liquid-phase outlet of described debutanizing tower connects one second cooler successively, one the 5th choke valve and a gas reducing liquid storage tank.
The liquid-phase outlet of described dethanizer first connects one first reboiler, described 4th choke valve is connected again by the liquid-phase outlet of described first reboiler, first gaseous phase outlet of described first reboiler connects back described dethanizer, and described first reboiler second gaseous phase outlet connects follow-up liquefaction unit.
The liquid-phase outlet of described debutanizing tower first connects one second reboiler, described second cooler is connected again by the liquid-phase outlet of described second reboiler, first gaseous phase outlet of described second reboiler connects back described debutanizing tower, and described second reboiler second gaseous phase outlet connects follow-up liquefaction unit.
Described ice chest adopts plate-fin heat exchanger, and described Natural gas expander adopts turbo-expander.
A kind of heavy hydrocarbon recovery process for LNG-FPSO, it comprises the following steps: 1) in chilldown system, gas-liquid two-phase cold-producing medium is after low pressure separator is separated, gas phase enters the first blender after the first compressor boost, the second compressor is mixed into the gas phase be separated from MP separator, the second blender is entered after the second compressor boost, the 3rd compressor is mixed into the gas phase be separated from high-pressure separator, the first cooler is entered after the 3rd compressor boost, liquid phase is become after the first cooler cooling, the cold-producing medium becoming gas-liquid two-phase through first throttle valve decrease temperature and pressure enters high-pressure separator, after high-pressure separator carries out gas-liquid separation, gas phase enters the second blender, liquid phase enters the first current divider, a part of liquid phase through the first current divider shunting enters high-pressure separator through there being the first pipeline in ice chest after providing cold, be first order refrigeration, 2) MP separator is entered after another part liquid phase of the first current divider shunting becomes gas-liquid two-phase via second throttle decrease temperature and pressure, after MP separator carries out gas-liquid separation, gas phase enters the first blender, liquid phase enters the second current divider, through second current divider shunting a part of liquid phase via ice chest in the second pipeline cold is provided after enter MP separator, be the second level refrigeration, 3) low pressure separator is entered after another part liquid phase of the second current divider shunting becomes gas-liquid two-phase via the 3rd choke valve decrease temperature and pressure, after low pressure separator carries out gas-liquid separation, gas phase enters the first compressor, liquid phase enters low pressure separator after the 3rd pipeline provides cold in ice chest, is third level refrigeration, 4) in heavy hydrocarbon piece-rate system, natural gas via enters ice chest by the 6th pipeline of ice chest, becomes gas-liquid two-phase enter gas-liquid separator through ice chest precooling cooling, 5) liquid phase gone out through gas-liquid separator separates enters the 4th pipeline in ice chest after the 6th choke valve carries out decrease temperature and pressure, and enter the upper entrance of dethanizer after cooling, the gas phase through gas-liquid separator separates enters Natural gas expander, 6) gas-liquid two-phase formed after Natural gas expander decrease temperature and pressure enters dethanizer, the natural gas obtaining de-heavy hydrocarbon at the gaseous phase outlet of dethanizer enters follow-up liquefaction unit, the liquid phase of the bottom of dethanizer generates gas-liquid two-phase after the first reboiler heats again, part gas phase is back to dethanizer through the first gaseous phase outlet of the first reboiler, another part gas phase enters follow-up liquefaction unit through the second gaseous phase outlet of the first reboiler, and liquid phase enters debutanizing tower after the 4th choke valve decrease temperature and pressure, 7) debutanization process is carried out at a part of liquid-phase reflux of gas phase after condenser condenses of debutanizing tower to dethanizer, another part liquid phase enters after in ice chest, the 5th pipeline cools, after the 7th choke valve step-down, enter storage tank store, the liquid phase of debutanizing tower bottom heats generation gas-liquid two-phase again through the second reboiler, part gas phase is back to debutanizing tower through the first gaseous phase outlet of the second reboiler and again carries out debutanization process, another part gas phase enters follow-up liquefaction unit through the second gaseous phase outlet of the second reboiler, liquid phase stream cools through the second cooler, enter gas reducing liquid storage tank after 5th choke valve step-down to store.
Cold-producing medium adopts propane.
All adopt seawater as cooling media in described first and second coolers.
The present invention is owing to taking above technical scheme, it has the following advantages: 1, the present invention utilizes chilldown system by ice chest for processing natural gas in heavy hydrocarbon piece-rate system and LPG provides three grades of colds, adopt this kind of technique can make full use of the cold of chilldown system, and in conjunction with the pressure energy of heavy hydrocarbon piece-rate system mesohigh natural gas self, make heavy hydrocarbon piece-rate system fully reclaim heavy hydrocarbon in natural gas, improve propane recovery to reach good economy.Heavy hydrocarbon piece-rate system of the present invention utilizes a gas-liquid separator, Natural gas expander, dethanizer, a debutanizing tower are separated with the heavy hydrocarbon that four choke valves realize high-pressure natural gas, this heavy hydrocarbon piece-rate system facility compact, simple, flow process valve member is few, is therefore very easily applied on marine LNG-FPSO.2, adopt unitary system cryogen to carry out inner loop in the present invention in chilldown system, greatly reduce the start-up time of a lot of auxiliary equipment thus, and not only can save the operations such as cold-producing medium proportioning, relative control structure is simplified; And when running into typhoon when to work at sea, can stop rapidly and enhance productivity.3, the present invention is provided with one first reboiler in the bottom of dethanizer, first reboiler is provided with the first gaseous phase outlet and the second gaseous phase outlet, first gaseous phase outlet tieback is to dethanizer, and the second gaseous phase outlet connects follow-up liquefaction unit, fully can improve the operating efficiency of dethanizer.4, present system is not only insensitive to the condition such as component, temperature, pressure of natural gas, present system facility compact, simple and product that is that refine all meets existing standard, the present invention can be widely used in the heavy hydrocarbon recovery process of the LNG-FPSO of ocean production environment.
Accompanying drawing explanation
Fig. 1 is process flow diagram of the present invention
Fig. 2 is cold box interior schematic diagram of the present invention
Detailed description of the invention
Below in conjunction with drawings and Examples, the present invention is described in detail.
As shown in Figure 1, present system comprises ice chest 10, chilldown system 20 and a heavy hydrocarbon piece-rate system 40.
Six pipelines 11,12,13,14,15,16 for heat exchange are provided with in ice chest 10 of the present invention.
Chilldown system 20 of the present invention comprises low pressure separator 21, first compressor 22, first blender 23, second compressor 24, second blender 25, the 3rd compressor 26, first cooler 27, first throttle valve 28, high-pressure separator 29, first current divider 30, second throttle 31, MP separator 32, second current divider 33 and the 3rd choke valve 34.
The entrance of low pressure separator 21 is connected the two ends of the 3rd pipeline 13 in ice chest 10 with liquid-phase outlet, the gaseous phase outlet of low pressure separator 21 connects the first compressor 22, first blender 23, second compressor 24, second blender 25, the 3rd compressor 26, first cooler 27, first throttle valve 28 and high-pressure separator 29 successively; The gaseous phase outlet of high-pressure separator 29 connects the gas phase entrance of the second blender 25, and the liquid-phase outlet of high-pressure separator 29 connects the first current divider 30; First outlet of the first current divider 30 connects the entrance of high-pressure separator 29 by the first pipeline 11 in ice chest 10, the second outlet of the first separator 30 connects MP separator 32 by second throttle 31; The gaseous phase outlet of MP separator 32 connects the gas phase entrance of the first blender 23, the liquid-phase outlet of MP separator 32 connects the second current divider 33, first outlet of the second current divider 33 connects the entrance of MP separator 32 by the second pipe 12 in ice chest 10, the second outlet of the second current divider 33 connects the entrance of low pressure separator 21 by the 3rd choke valve 34.
Heavy hydrocarbon piece-rate system 40 of the present invention comprises gas-liquid separator 41, Natural gas expander 42, dethanizer 43, the 4th choke valve 44, debutanizing tower 45, second cooler 46, the 5th choke valve 47, NGL (gas reducing liquid) storage tank the 48, the 6th choke valve 49, the 7th choke valve 50, LPG (liquefied petroleum gas) storage tank 51.
In ice chest 10, the entrance of the 6th pipeline 16 connects gas pipeline, and outlet connects gas-liquid separator 41, Natural gas expander 42 and dethanizer 43 successively; The liquid-phase outlet of gas-liquid separator 41 is connected the upper entrance of dethanizer 43 by the 6th choke valve 49 and the 4th pipeline 14 in ice chest 10, the gaseous phase outlet of dethanizer 43 connects fuel gas for station, the liquid-phase outlet of dethanizer 43 connects the upper entrance of debutanizing tower 45 by the 4th choke valve 44, the gaseous phase outlet of debutanizing tower 45 connects a condenser 52, the exit end of condenser 52 connects back debutanizing tower 45, and the other end is connected LPG storage tank 51 by the 5th pipeline 15 in ice chest 10 with the 7th choke valve 50.The liquid-phase outlet of debutanizing tower 45 connects the second cooler 46, the 5th choke valve 47 and NGL storage tank 48 successively.
In above-described embodiment, the liquid-phase outlet of dethanizer 43 first can connect one first reboiler 53, connect back dethanizer 43 by the first gaseous phase outlet of liquid-phase outlet connection the 4th choke valve 44, first reboiler 53 of the first reboiler 53 again, the second gaseous phase outlet connects follow-up liquefaction unit.The liquid-phase outlet of same debutanizing tower 45 first can connect one second reboiler 54, the second cooler 46 is connected again by the liquid-phase outlet of the second reboiler 54, first gaseous phase outlet of the second reboiler 54 connects back debutanizing tower 45, and the second gaseous phase outlet connects follow-up liquefaction unit.
In above-described embodiment, ice chest 10 can adopt plate-fin heat exchanger, and propane can be adopted as cold-producing medium in chilldown system 20, seawater can be adopted as cooling media in the first cooler 27, Natural gas expander 42 can adopt turbo-expander.First throttle valve 28, second throttle 31, the 3rd choke valve 34, the 4th choke valve 44, the 5th choke valve 47 and the 6th choke valve 49 adopt J-T valve (Joule-Thomson throttle expansion valve).
The invention allows for a kind of heavy hydrocarbon recovery process for LNG-FPSO, it comprises the following steps:
1) in chilldown system 20, gas-liquid two-phase cold-producing medium is after low pressure separator 21 is separated, gas phase enters the first blender 23 after the first compressor 22 supercharging, the second compressor 24 is mixed into the gas phase be separated from MP separator 32, the second blender 25 is entered after the second compressor 24 supercharging, the 3rd compressor 26 is mixed into the gas phase be separated from high-pressure separator 29, the first cooler 27 is entered after the 3rd compressor 26 supercharging, liquid phase is become after the first cooler 27 is lowered the temperature, the cold-producing medium becoming gas-liquid two-phase through first throttle valve 28 decrease temperature and pressure enters high-pressure separator 29, after high-pressure separator 29 carries out gas-liquid separation, gas phase enters the second blender 25, liquid phase enters the first current divider 30, the a part of liquid phase shunted through the first current divider 30 enters high-pressure separator 29 through having after first pipeline 11 provides cold in ice chest 10, be first order refrigeration.
2) MP separator 32 is entered after another part liquid phase that the first current divider 30 is shunted becomes gas-liquid two-phase via second throttle 31 decrease temperature and pressure, after MP separator 32 carries out gas-liquid separation, gas phase enters the first blender 23, liquid phase enters the second current divider 33, through second current divider 33 shunt a part of liquid phase via ice chest 10 in the second pipeline 12 cold is provided after enter MP separator 32, be the second level refrigeration.
3) low pressure separator 21 is entered after another part liquid phase that the second current divider 33 is shunted becomes gas-liquid two-phase via the 3rd choke valve 34 decrease temperature and pressure, after low pressure separator 21 carries out gas-liquid separation, gas phase enters the first compressor 22, liquid phase enters low pressure separator 21 after the 3rd pipeline 13 provides cold in ice chest 10, is third level refrigeration.
4) in heavy hydrocarbon piece-rate system 40, natural gas via enters ice chest 10 by the 6th pipeline 16 of ice chest 10, becomes gas-liquid two-phase enter gas-liquid separator 41 through ice chest 10 precooling cooling.
5) after the 6th choke valve 49 carries out decrease temperature and pressure, the 4th pipeline 14 in ice chest 10 is entered through the isolated liquid phase of gas-liquid separator 41, enter the upper entrance of dethanizer 43 after cooling, the gas phase be separated through gas-liquid separator 41 enters Natural gas expander 42.
6) gas-liquid two-phase formed after Natural gas expander 42 decrease temperature and pressure enters dethanizer 43, the natural gas obtaining de-heavy hydrocarbon at the gaseous phase outlet of dethanizer 43 enters follow-up liquefaction unit, the liquid phase of the bottom of dethanizer 43 generates gas-liquid two-phase after the first reboiler 53 heats again, part gas phase is back to dethanizer 43 through the first gaseous phase outlet of the first reboiler 53, another part gas phase enters follow-up liquefaction unit through the second gaseous phase outlet of the first reboiler 53, and liquid phase enters debutanizing tower 45 after the 4th choke valve 44 decrease temperature and pressure.
7) debutanization process is carried out through the condensed a part of liquid-phase reflux of condenser 52 to dethanizer 45 in the gas phase of debutanizing tower 45, another part liquid phase enters after in ice chest 10, the 5th pipeline 15 cools, and enters LPG storage tank 51 and store after the 7th choke valve 50 step-down.The liquid phase of debutanizing tower 45 bottom heats generation gas-liquid two-phase again through the second reboiler 54, part gas phase is back to debutanizing tower 45 through the first gaseous phase outlet of the second reboiler 54 and again carries out debutanization process, another part gas phase enters follow-up liquefaction unit through the second gaseous phase outlet of the second reboiler 54, and liquid phase stream cools through the second cooler 46, enter NGL storage tank 48 after the 5th choke valve 47 step-down stores.
As shown in Figure 2, in ice chest 10 schematic internal view, 61 ~ 62 is the one-level process of refrigerastion of natural gas and LPG of freezing in ice chest 10 after refrigeration throttling.63 ~ 64 secondary process of refrigerastions that are freeze in ice chest 10 after cold-producing medium throttling natural gas and LPG.65 ~ 66 cold processes of three tier structure that are freeze in ice chest 10 after cold-producing medium throttling natural gas and LPG.67 ~ 68 is the process of refrigerastion of liquid natural gas after the 6th choke valve 49 decrease temperature and pressure in ice chest 10 be separated through gas-liquid separator 41.69 ~ 70 is the cooling procedure of natural gas in ice chest 10.71 ~ 72 is the cooling procedure of LPG in ice chest 10.
In above-described embodiment, in step 1) chilldown system 20 in, cold-producing medium adopt propane.
In above-described embodiment, in step 1) in the first cooler and step 7) in the second cooler in all adopt seawater as cooling media.
Enumerate a specific embodiment below:
1) in chilldown system 20, cold-producing medium adopts propane, the propane of gas-liquid two-phase is after low pressure separator 21 is separated, gas phase is pressurized to-5.2 DEG C through the first compressor 22, the first blender 23 is entered after 0.29MPa, the second compressor 24 is entered after the gas phase be separated with from MP separator 32 mixes, 15.9 are pressurized to through the second compressor 24, the second blender 25 is entered after 0.55MPa, the 3rd compressor 26 is entered after the gas phase be separated with from high-pressure separator 29 mixes, 52.2 DEG C are pressurized to through the 3rd compressor 26, the first cooler 27 is entered after 1.36MPa, all liquefy through the first cooler 27 propane after 31 DEG C that cools, through first throttle valve 28 decrease temperature and pressure to 5 DEG C, the gas-liquid two-phase propane of 0.55MPa enters high-pressure separator 29, after high-pressure separator 29 carries out gas-liquid separation, gas phase enters the second blender 25, liquid phase enters the first current divider 30, through first current divider 30 shunt a part of liquid phase via ice chest 10 in the first pipeline 11 cold is provided after enter high-pressure separator 29, be first order refrigeration,
2) another part liquid phase of shunting of the first current divider 30 via second throttle 31 decrease temperature and pressure to-15 DEG C, the gas-liquid two-phase of 0.29MPa enters MP separator 32, after Central Asia separator 32 carries out gas-liquid separation, gas phase enters the first blender 23, liquid phase enters the second current divider 33, the a part of liquid phase shunted through the second current divider 33 enters Central Asia separator 32 after second pipeline 12 provides cold in ice chest 10, is second level refrigeration;
3) another part liquid phase of shunting of the second current divider 33 via the 3rd choke valve 34 decrease temperature and pressure to-36 DEG C, the gas-liquid two-phase of 0.13MPa enters low pressure separator 21, after low pressure separator 21 carries out gas-liquid separation, gas phase enters the first compressor 22, liquid phase enters low pressure separator 21 after the 3rd pipeline 13 provides cold in ice chest 10, is third level refrigeration;
4) in heavy hydrocarbon piece-rate system, latter 36 DEG C of depickling dehydration, 7.14MPa natural gas via enters ice chest 10 by the 6th pipeline 16 in ice chest 10, becomes-32 DEG C, the gas-liquid two-phase of 7.09MPa enters gas-liquid separator 41 through ice chest 10 precooling cooling;
5) after the 6th choke valve 49 decrease temperature and pressure extremely-40.54 DEG C, 4.6MPa, the 4th pipeline 14 of ice chest 10 is entered through the isolated liquid phase of gas-liquid separator 41, rise to 31 DEG C after carrying out cooling rewarming, be depressurized to the upper entrance that 4.55MPa enters dethanizer 43, enter Natural gas expander 42 through the isolated gas phase of gas-liquid separator 41;
6) after Natural gas expander 42 decrease temperature and pressure-55.35 DEG C, 4.5MPa formed gas-liquid two-phase enter dethanizer 43;
7) obtain removing the ethane of heavy hydrocarbon at the tower top of dethanizer 43 and enter fuel gas for station, the liquid phase of dethanizer 43 generates gas-liquid two-phase after the first reboiler 53 heats again, a gas phase part is back to dethanizer 43 through the first gaseous phase outlet of the first reboiler 53 and again carries out deethanization process, another part through the second gaseous phase outlet of the first reboiler 53 to follow-up liquefaction unit; 140 DEG C, the liquid phase stream of 4.5MPa enters debutanizing tower 45 after the 5th choke valve 46 is depressurized to 0.65MPa;
8) in the gas phase that the gaseous phase outlet of debutanizing tower 45 obtains, debutanizing tower 45 is again back to through condenser 52 condensation part liquid phase, another part 18.11 DEG C, 0.55MPa liquid phase enter the 5th pipeline 15 in ice chest 10 and cool to-32 DEG C, enter LPG storage tank 51 and store after the 7th choke valve 50 is depressurized to 0.12MPa.The liquid phase of debutanizing tower 45 bottom heats generation gas-liquid two-phase again through the second reboiler 54, gas phase is back in debutanizing tower 45 carries out debutanization process, 139 DEG C, the liquid phase stream of 0.6MPa is cooled to-19.8 DEG C through the second cooler 46, the 5th choke valve 47 enters NGL storage tank 48 after being depressurized to 0.12MPa and store.
The various embodiments described above are only for illustration of the present invention, and wherein the structure, connected mode etc. of each parts all can change to some extent, and every equivalents of carrying out on the basis of technical solution of the present invention and improvement, all should not get rid of outside protection scope of the present invention.
Claims (8)
1. for a heavy hydrocarbon recovery system of LNG-FPSO, it is characterized in that: it comprises an ice chest, a chilldown system and a heavy hydrocarbon piece-rate system;
Six pipelines for heat exchange are provided with in described ice chest;
Described chilldown system comprises a low pressure separator, the entrance of described low pressure separator is connected the two ends of the 3rd pipeline in described ice chest with liquid-phase outlet, the gaseous phase outlet of described low pressure separator connects one first compressor, one first blender, one second compressor, one second blender, one the 3rd compressor, a water cooler, a first throttle valve and a high-pressure separator successively; The gaseous phase outlet of described high-pressure separator connects the gas phase entrance of described second blender, and the liquid-phase outlet of described high-pressure separator connects one first current divider; First outlet of described first current divider connects the entrance of described high-pressure separator by the first pipeline in described ice chest, and the second outlet of described first current divider connects a MP separator by a second throttle; The gaseous phase outlet of described MP separator connects the gas phase entrance of described first blender, and the liquid-phase outlet of described MP separator connects one second current divider; First outlet of described second current divider connects the entrance of described MP separator by the second pipeline in described ice chest, and the second outlet of described second current divider connects the entrance of described low pressure separator by one the 3rd choke valve;
In described ice chest, the entrance of the 6th pipeline connects gas pipeline, exports the gas-liquid separator, a Natural gas expander and the dethanizer that connect successively in described heavy hydrocarbon piece-rate system, the liquid-phase outlet of described gas-liquid separator is connected the upper entrance of described dethanizer by one the 6th choke valve and the 4th pipeline in described ice chest, the gaseous phase outlet of described dethanizer connects fuel gas for station, the liquid-phase outlet of described dethanizer connects the upper entrance of a debutanizing tower by one the 4th choke valve, the gaseous phase outlet of described debutanizing tower connects a condenser, the exit end of described condenser connects back described debutanizing tower, the other end is connected a liquefied petroleum gas storage tank by the 5th pipeline in described ice chest with one the 7th choke valve, the liquid-phase outlet of described debutanizing tower connects one second cooler successively, one the 5th choke valve and a gas reducing liquid storage tank.
2. a kind of heavy hydrocarbon recovery system for LNG-FPSO as claimed in claim 1, it is characterized in that: the liquid-phase outlet of described dethanizer first connects one first reboiler, described 4th choke valve is connected again by the liquid-phase outlet of described first reboiler, first gaseous phase outlet of described first reboiler connects back described dethanizer, and described first reboiler second gaseous phase outlet connects follow-up liquefaction unit.
3. a kind of heavy hydrocarbon recovery system for LNG-FPSO as claimed in claim 1, it is characterized in that: the liquid-phase outlet of described debutanizing tower first connects one second reboiler, described second cooler is connected again by the liquid-phase outlet of described second reboiler, first gaseous phase outlet of described second reboiler connects back described debutanizing tower, and described second reboiler second gaseous phase outlet connects follow-up liquefaction unit.
4. a kind of heavy hydrocarbon recovery system for LNG-FPSO as claimed in claim 2, it is characterized in that: the liquid-phase outlet of described debutanizing tower first connects one second reboiler, described second cooler is connected again by the liquid-phase outlet of described second reboiler, first gaseous phase outlet of described second reboiler connects back described debutanizing tower, and described second reboiler second gaseous phase outlet connects follow-up liquefaction unit.
5. a kind of heavy hydrocarbon recovery system for LNG-FPSO as claimed in claim 1 or 2 or 3 or 4, is characterized in that: described ice chest adopts plate-fin heat exchanger, and described Natural gas expander adopts turbo-expander.
6. adopt a recovery process for the heavy hydrocarbon recovery system for LNG-FPSO as described in any one of Claims 1 to 5, it comprises the following steps:
1) in chilldown system, gas-liquid two-phase cold-producing medium is after low pressure separator is separated, gas phase enters the first blender after the first compressor boost, the second compressor is mixed into the gas phase be separated from MP separator, the second blender is entered after the second compressor boost, the 3rd compressor is mixed into the gas phase be separated from high-pressure separator, the first cooler is entered after the 3rd compressor boost, liquid phase is become after the first cooler cooling, the cold-producing medium becoming gas-liquid two-phase through first throttle valve decrease temperature and pressure enters high-pressure separator, after high-pressure separator carries out gas-liquid separation, gas phase enters the second blender, liquid phase enters the first current divider, a part of liquid phase through the first current divider shunting enters high-pressure separator through there being the first pipeline in ice chest after providing cold, be first order refrigeration,
2) MP separator is entered after another part liquid phase of the first current divider shunting becomes gas-liquid two-phase via second throttle decrease temperature and pressure, after MP separator carries out gas-liquid separation, gas phase enters the first blender, liquid phase enters the second current divider, through second current divider shunting a part of liquid phase via ice chest in the second pipeline cold is provided after enter MP separator, be the second level refrigeration;
3) low pressure separator is entered after another part liquid phase of the second current divider shunting becomes gas-liquid two-phase via the 3rd choke valve decrease temperature and pressure, after low pressure separator carries out gas-liquid separation, gas phase enters the first compressor, liquid phase enters low pressure separator after the 3rd pipeline provides cold in ice chest, is third level refrigeration;
4) in heavy hydrocarbon piece-rate system, natural gas via enters ice chest by the 6th pipeline of ice chest, becomes gas-liquid two-phase enter gas-liquid separator through ice chest precooling cooling;
5) liquid phase gone out through gas-liquid separator separates enters the 4th pipeline in ice chest after the 6th choke valve carries out decrease temperature and pressure, and enter the upper entrance of dethanizer after cooling, the gas phase through gas-liquid separator separates enters Natural gas expander;
6) gas-liquid two-phase formed after Natural gas expander decrease temperature and pressure enters dethanizer, the natural gas obtaining de-heavy hydrocarbon at the gaseous phase outlet of dethanizer enters follow-up liquefaction unit, the liquid phase of the bottom of dethanizer generates gas-liquid two-phase after the first reboiler heats again, part gas phase is back to dethanizer through the first gaseous phase outlet of the first reboiler, another part gas phase enters follow-up liquefaction unit through the second gaseous phase outlet of the first reboiler, and liquid phase enters debutanizing tower after the 4th choke valve decrease temperature and pressure;
7) debutanization process is carried out at a part of liquid-phase reflux of gas phase after condenser condenses of debutanizing tower to dethanizer, another part liquid phase enters after in ice chest, the 5th pipeline cools, after the 7th choke valve step-down, enter storage tank store, the liquid phase of debutanizing tower bottom heats generation gas-liquid two-phase again through the second reboiler, part gas phase is back to debutanizing tower through the first gaseous phase outlet of the second reboiler and again carries out debutanization process, another part gas phase enters follow-up liquefaction unit through the second gaseous phase outlet of the second reboiler, liquid phase stream cools through the second cooler, enter gas reducing liquid storage tank after 5th choke valve step-down to store.
7. a kind of heavy hydrocarbon recovery process for LNG-FPSO as claimed in claim 6, is characterized in that: cold-producing medium adopts propane.
8. a kind of heavy hydrocarbon recovery process for LNG-FPSO as claimed in claim 7, is characterized in that: all adopt seawater as cooling media in described first and second coolers.
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