摘要:
A method, system and compositions for refrigerating and liquefying a feed gas at high ambient temperatures using a multi-staged air-cooled liquefier is provided. The method includes cooling the feed gas in at least a first stage using a first refrigerant composition and a second stage using a second refrigerant composition to liquefy the feed gas, expanding the feed gas and passing the feed gas through a phase separator to obtain the liquefied feed gas and vapor phase components separately. The system includes a compressor, a condenser, a throttle, and a heat exchanger for each stage. The first stage and second stage are coupled at a first heat exchanger (HX-3) and a second heat exchanger (HX-6). The system results in an improved production capacity of at least 40% over a system lacking the second heat exchanger (HX-6).
摘要:
Processes and systems are provided for recovering a liquefied natural gas (LNG) stream from a hydrocarbon-containing feed gas stream using dual closed- loop mixed refrigerant cycles. In particular, the processes and systems described herein can be used to efficiently and effectively liquefy methane from a hydrocarbon-containing feed gas stream by utilizing a first refrigeration system and a second refrigeration system in fluid communication with a turboexpander and separator.
摘要:
The invention relates to a process for liquefying natural gas, in which the natural gas is cooled, condensed and subcooled by indirect heat exchange with two refrigerant mixtures circulating in the circuits (I) and (II). A first refrigerant mixture is compressed, cooled and at least partially condensed by heat exchange in C1 with an external fluid. The first refrigerant mixture is then subcooled by heat exchange in C2 before being partially or completely expanded so as to cool the natural gas and a second refrigerant mixture by heat exchange. The second refrigerant mixture is compressed, cooled and at least partially condensed by heat exchange in C3 with an external fluid before being cooled in the first circuit (I) by heat exchange with the first refrigerant mixture so as to be subsequently expanded and to allow the natural gas to be cooled, by heat exchange, until it is liquefied. The first and second refrigerant mixtures comprise at least ethylene.
摘要:
A fluid is cooled and liquefied in an apparatus with a heat exchanger (5) having a shell side (78) within its walls (85) and a plurality of flow passages extending through the shell side (78). The plurality of flow passages comprises two or more primary groups (40a, 40b) of one or more primary flow passages, each said primary group for carrying a part of the fluid stream through the heat exchanger (5) and to indirectly cool said part against a refrigerant in the shell side (78) of the heat exchanger (5) to provide a liquefied fluid stream (50, 70). A primary inlet header (6,6') connects the two or more primary groups (40a, 40b) of primary flow passages to a source of the fluid (10), and arranged to split the fluid stream between the two or more primary groups (40a, 40b) of primary flow passages. Means (25a, 25b) are provided for selectively blocking at least one of the two or more primary groups (40a, 40b) of primary flow passages whilst allowing the fluid stream to flow through the remaining unblocked primary groups of primary flow passages.
摘要:
Nitrogen is removed from a cryogenic hydrocarbon composition. A least a first portion of the cryogenic hydrocarbon composition is fed to a nitrogen stripper column. The nitrogen stripper column operates at a stripping pressure. A stripping vapour is passed into the nitrogen stripper column, comprising at least a stripping portion of a compressed process vapour that has been produced from the nitrogen-stripped liquid which has been depressurized after drawing it from the nitrogen stripper column. Reflux is generated involving partially condensing overhead vapour of the nitrogen stripper column by passing heat from the overhead vapour to an auxiliary refrigerant stream at a cooling duty. An off gas consisting of a, non-condensed, vapour fraction from the overhead vapour is discharged. The cooling duty is adjusted to regulate a heating value of the vapour fraction being discharged.
摘要:
Nitrogen is removed from a cryogenic hydrocarbon composition. A least a first portion of the cryogenic hydrocarbon composition is fed to a nitrogen stripper column as a first nitrogen stripper feed stream. A nitrogen-stripped liquid is drawn from the nitrogen stripper column. A liquid hydrocarbon product stream and a process vapour are produced comprising at least a step of depressurizing the nitrogen-stripped liquid to a flash pressure. The process vapour is compressed, and selectively split into a stripping portion and a non-stripping portion. A stripping vapour stream comprising at least the stripping portion is passed into the nitrogen stripper column. A vapour fraction is discharged as off gas, comprising a discharge fraction of overhead vapour from the nitrogen stripper column and comprising at least the bypass portion from the non-stripping portion of the compressed vapour, which bypasses a stripping section positioned in the nitrogen stripper column.
摘要:
A hydrocarbon stream (3) is cooled by passing the hydrocarbon stream through at least one heat exchanger (1, 2) by a method, which comprises the steps of: (a) compressing a refrigerant (32, 15) in a compressor unit to yield compressed refrigerant (30,10); (b) expanding (46, 13) the compressed refrigerant (47, 14), to yield cold refrigerant; (c) passing the hydrocarbon stream (3) against the cold refrigerant in the heat exchanger (1, 2) designed for a maximum inlet flow of the refrigerant, to yield a cooled hydrocarbon stream (4, 7) and at least partly evaporated refrigerant; (d) recovering the cold hydrocarbon stream (8, 9); and (e) recycling (32, 15) at least part of the at least partly evaporated refrigerant to the compressor unit, wherein the compressor unit comprises at least two compressors (36, 38, 40, 17, 21, 23) that all operate simultaneously in parallel and wherein the compressor unit has a design capacity in excess of the maximum inlet flow of refrigerant to the heat exchanger. The invention also provides an apparatus for this method.
摘要:
The natural gas liquefaction process according to the present invention uses a single refrigeration cycle adopting a mixed refrigerant, and therefore has a simple structure and a compact system which is easy to operate. After the mixed refrigerant is divided into two refrigerant parts, the two refrigerant parts are not mixed with each other but go through condensation (cooling), expansion, heat exchange, and compression stages individually, and thus, optimal temperature and pressure conditions are applied to each of the divided refrigerant parts to increase efficiency of the liquefaction process.
摘要:
The invention relates to a liquefaction method that comprises fractioning the natural gas with ethane recycling in order to enhance propane recovery and to increase the critical pressure of the gas to be liquefied. The natural gas is partially liquefied by cooling in E1, than separated in the fractioning column (2) into a methane-rich flow and flow rich in hydrocarbons heavier than methane. The methane-rich flow is partially liquefied in (3), and the condensates separated in the tank (4) are recycled to the head of the column (2) via the duct (7). The gaseous fraction from the tank (4) is liquefied in the exchanger (E2) in order to produce liquefied natural gas. The flow rich in hydrocarbons heavier than methane is separated in the de-ethaniser into an ethane-enriched fraction and heavier hydrocarbons. According to the invention, the ethane-enriched fraction is at least partially liquefied, and a portion of the liquefied ethane is recycled into the separation tank (4) or the reflux line (7).
摘要:
Method and apparatus for producing a cooled hydrocarbon stream (60). The method employs cooling, at at least two consecutive pressure levels, a first stream and a first mixed refrigerant stream, using portions of the first mixed refrigerant from the first mixed refrigerant stream in first and second heat exchangers (125, 145); first and second expansion devices (135, 165); and a first compressor (105) to provide the first mixed refrigerant stream. The cooling process is controlled using an advanced process controller based on model predictive control to determine simultaneously control actions for a set of manipulated variables in order to optimise at least one of a set of parameters whilst controlling at least one of a set of controlled variables. The set of manipulated variables comprises: the composition of the mixed first refrigerant, the setting of the first expansion device (135), and the setting of the second expansion device (165).