摘要:
A natural gas liquefaction train (100, 100a-100n) includes a nitrogen cooling loop. A controller (208a-208n, 300) is provided for controlling one or more controlled variables by adjusting one or more manipulated variables. The one or more manipulated variables may include a nitrogen flow associated with the nitrogen cooling loop in the natural gas liquefaction train. The controller could adjust the nitrogen flow by adjusting operation of a compressor (178) associated with the nitrogen cooling loop. The one or more controlled variables may include a rundown temperature of liquefied natural gas exiting the nitrogen loop and/or a calorific or heating value of the liquefied natural gas exiting the nitrogen loop. A second controller (206a-206n) could control other aspects of the natural gas liquefaction train, such as by controlling a mass flow rate of a feed gas in the natural gas liquefaction train.
摘要:
A method for liquefying a stream rich in hydrocarbons, in particular, a natural gas stream is disclosed, wherein the liquefying of the stream rich in hydrocarbons is carried out in a cascade comprising three refrigeration circuits and the first refrigeration circuit carries out the precooling, the second refrigerant circuit carries out the liquefying and the third refrigerant circuit carries out the supercooling of the stream rich in hydrocarbons. According to the invention, the refrigerant in the refrigerant circuit for the precooling (E1) of the stream rich in hydrocarbons contains (a - a"") C 3 H 8 , C 3 H 6 , C 2 H 6 or C 2 H 4 in a concentration fo at least 95 Vol. % and the temperature difference between the boiling point and the dew point of the refrigerant is less than 5 °C.
摘要:
Method and apparatus for liquefying a hydrocarbon stream such as natural gas from a feed stream. The method comprises at least the steps of : (a) providing the feed stream (10); (b) first cooling the feed stream (10) against a first cooling refrigerant being cycled in a first cooling refrigerant circuit (100), thereby obtaining a cooled gas stream (20), wherein the first cooling refrigerant comprises > 90 mol% propane; (c) second cooling the cooled gas stream (20) obtained in step (b) into a liquid against a first mixed refrigerant being cycled in a first mixed refrigerant circuit (200), wherein said second cooling is in two or more heat exchangers (42, 44), at least two of which are operating at different pressures, thereby obtaining a liquefied stream (60); and (d) sub-cooling the liquefied stream (60) obtained in step (c) against a second mixed refrigerant or against a nitrogen refrigerant being cycled in a sub-cooling refrigerant circuit (300), thereby obtaining a sub-cooled hydrocarbon stream (70).
摘要:
Contemplated plants include a NGL recovery portion and a LNG liquefaction portion, wherein the NGL recovery portion provides a low-temperature and high-pressure overhead product directly to the LNG liquefaction portion. Feed gas cooling and condensation are most preferably performed using refrigeration cycles that employ refrigerants other than the demethanizer/absorber overhead product. Thus, cold demethanizer/absorber overhead product is compressed with the turbo-expansion and delivered to a liquefaction portion at significantly lower temperature and higher pressure without net compression energy expenditure.
摘要:
A semi-closed loop system for producing liquefied natural gas (LNG) that combines certain advantages of closed-loop systems with certain advantages of open-loop systems to provide a more efficient and effective hybrid system. In the semi-closed loop system, the final methane refrigeration cycle provides significant cooling of the natural gas stream via indirect heat transfer, as opposed to expansion-type cooling. A minor portion of the LNG product from the methane refrigeration cycle is used as make-up refrigerant in the methane refrigeration cycle. A pressurized portion of the refrigerant from the methane refrigeration cycle is employed as fuel gas. Excess refrigerant from the methane refrigeration cycle can be recombined with the processed natural gas stream, rather than flared.
摘要:
A gas (1) is liquefied by cooling successively through at least two temperature ranges by vaporization of respective refrigerants (117, 213 & 315) with the vaporizing refrigerant providing the coldest temperature range further vaporizing (317) at temperatures above the highest temperature of that range. The partially vaporized refrigerant (316) that provided the coldest temperature range preferably is further vaporized (317) against a compressed return vapor (328) in a recirculating refrigeration system.
摘要:
The LNG plant comprises a compression train (100) and a further compression train (200), and may advantageously implement for example 3-cycles pure-refrigerants liquefaction technologies or multiple-cycles pure-refrigerant and mixed-refrigerant liquefaction technologies. The compression train (100) comprises a first and a second set of axial compression stages (321, 322, 323), one main inlet (301), one main outlet (302), one auxiliary inlet (303) and/or one auxiliary outlet, wherein a fluid entering the compressor (130) through the auxiliary inlet (303) is redirected from a substantially radial direction to a substantially axial direction and/or a fluid exiting the compressor (130) through the auxiliary outlet is redirected from a substantially axial direction to a substantially radial direction. The further compression train (200) comprises a first set of impellers (411, 412) being centrifugal and unshrouded and a second set of impellers (421, 422, 423) being centrifugal and shrouded.
摘要:
The invention relates to a method which includes passing the feedstream (12) into a first heat exchanger (16) to perform a heat exchange with a stream (60) of gaseous coolant produced in a first refrigeration cycle (26) including a first dynamic turbo-expander (34). The method includes passing a precooled feedstream (18) into a second heat exchanger (20) to perform a heat exchange with a second stream (62) of gaseous coolant produced in a second refrigeration cycle (28) including a second dynamic turbo-expander (42). The method includes passing a stream of liquefied natural gas (22) into a third heat exchanger to perform a heat exchange with a third stream (64) of coolant produced in a third refrigeration cycle (30) including a third dynamic turbo-expander (52), distinct from the first turbo-expander (34) and from the second turbo-expander (42).
摘要:
A system and method for cooling and liquefying a gas in a heat exchanger that includes compressing and cooling a mixed refiigerant using first and last compression and cooling cycles so that high pressure liquid and vapor streams are formed, The high pressure liquid and vapor streams are cooled in the heat exchanger and then expanded so that a primary refrigeration stream is provided in the heat exchanger. The mixed refrigerant is cooled and equilibrated between the first and last compression and cooling cycles so that a pre-cool liquid stream is formed and subcooled in the heat exchanger. The stream is then expanded and passed through the heat exchanger as a pre-cool refrigeration stream. A stream of gas is passed through the heat exchanger in countercurrent heat exchange with the primary refrigeration stream and the pre-cool refrigeration stream so that the gas is cooled.
摘要:
Method of driving two or more refrigerant compressors in a hydrocarbon cooling process. In such a hydrocarbon cooling process a hydrocarbon feed stream (10) may be passed against partly evaporating refrigerant streams. The at least partly evaporated refrigerant streams (35a, 37a) are compressed through refrigerant compressors (34, 36). One or more gas turbines (54) are driven to provide electrical power (56) and hot gas. The hot gas (57) is passed through one or more steam heat exchangers (58) to provide steam power, which is used to drive one or more steam turbines (82) to drive at least one of the refrigerant compressors (34). The electrical power is used to drive (76) at least another one of the refrigerant compressors (36).