KR20190096958A - Natural gas liquefaction system with integrated-gear turbo-compressor - Google Patents

Abstract

According to one aspect of the disclosure, a natural gas liquefaction system 100 is provided. The system includes an integrated-gear turbo-compressor 150 having a plurality of compressor stages; A prime mover 160 for driving the compressor; This is a pre-cooling loop adapted to circulate the first refrigerant, wherein the at least one first compressor stage 151 of the plurality of compressor stages is adapted to pressurize the first refrigerant. ; A cooling loop adapted to circulate the second refrigerant therethrough, wherein one or more second compressor stages 155 of the plurality of compressor stages are adapted to pressurize the second refrigerant; A first heat exchanger device 170 for transferring heat from natural gas and / or from the second refrigerant to the first refrigerant; And a second heat exchanger device 180 for transferring heat from natural gas to the second refrigerant. Further aspects relate to compressor arrangements for natural gas liquefaction systems. Still further embodiments relate to a method of liquefying natural gas.

Description

Natural gas liquefaction system with integrated-gear turbo-compressor

The present disclosure relates to systems and methods for liquefying natural gas. More specifically, the present disclosure relates to a compressor arrangement comprising an integrated-gear turbo-compressor as well as a system for liquefying natural gas with an integrated-gear turbo-compressor. The present disclosure also relates to a method of liquefying natural gas with an integrated-gear turbo-compressor.

Natural gas is becoming an increasingly important source of energy. In order to enable cost-effective transport of natural gas from the source to the place of use, it is advantageous to reduce the volume of gas. Cryogenic liquefaction, which is more convenient, cheaper and safer to store and transport, has become a routine process for converting natural gas into liquid. By maintaining the gas cooled and liquefied to a temperature lower than the liquefaction temperature at ambient pressure, transportation of the liquefied natural gas (LNG) by pipeline or ship is made possible at ambient pressure.

In order to store and transport natural gas in the liquid state, the natural gas is preferably cooled to approximately -150 to -170 ° C, with the gas having a vapor pressure of approximately atmospheric pressure.

For liquefaction of natural gas providing a step of sequentially passing natural gas at elevated pressure through a plurality of cooling stages where the gas is continuously cooled to a lower temperature by a sequential refrigeration cycle until a liquefaction temperature is achieved. Several processes and systems are known.

Before passing natural gas through the cooling step, the natural gas is typically pretreated to disrupt processing, damage machinery or remove unwanted impurities from the final product. Impurities include acid gases, sulfur compounds, carbon dioxide, mercaptans, water and mercury. The pretreated gas from which impurities are removed is typically cooled by a refrigerant stream to separate heavier hydrocarbons. The remaining gas consists mainly of methane and generally contains less than 0.1% higher molecular weight hydrocarbons such as propane or heavier hydrocarbons. Cleaned and purified natural gas is cooled to the final temperature in the cryogenic section. The LNG obtained can be stored and transported at near atmospheric pressure.

Cryogenic liquefaction is generally carried out by means of a multi-cycle process, ie a process using two or more refrigeration cycles. Each cycle may use different refrigerants, depending on the type of process, or alternatively the same refrigerant may be used in two or more cycles. In a typical cryogenic liquefaction system, for example in the so-called APCI process, natural gas is first cooled by the first refrigerant circulating in the pre-cooling loop and then by the second refrigerant circulating in the cooling loop.

In the pre-cooling loop, the circulating first refrigerant can be compressed, condensed and expanded to subsequently remove heat from the natural gas. In the cooling loop, the circulating second refrigerant can be compressed and cooled to subsequently remove heat from the natural gas. However, driving two cooling loops (pre-cooling loop and cooling loop) is energy-intensive, cost-intensive and space-consuming.

Therefore, it would be beneficial to design and provide a method and system for liquefying natural gas that provides better energy efficiency and consumes less space.

In light of the above, natural gas liquefaction systems, compressor arrangements as well as methods for liquefying natural gas are provided.

According to one aspect of the disclosure, a natural gas liquefaction system is provided. The system comprises: an integrated-gear turbo-compressor having a plurality of compressor stages; A prime mover for driving said compressor; A pre-cooling loop adapted to circulate the first refrigerant, wherein the at least one first compressor stage of the plurality of compressor stages is adapted to pressurize the first refrigerant; A cooling loop adapted to circulate a second refrigerant therethrough, wherein one or more second compressor stages of the plurality of compressor stages are adapted to pressurize the second refrigerant; A first heat exchanger device for transferring heat from natural gas and / or from a second refrigerant to the first refrigerant; And a second heat exchanger device for transferring heat from natural gas to the second refrigerant.

An integrated-gear turbo-compressor according to an embodiment described herein comprises at least one force transmission mechanism, in particular a gear, connected between two or more compressor stages of a plurality of compressor stages.

According to yet another aspect, a compressor arrangement for compressing a plurality of refrigerants is provided. The compressor array comprises: an integrated-gear turbo-compressor having a plurality of compressor stages; A first cooling loop adapted to circulate the first refrigerant, wherein the at least one first compressor stage of the plurality of compressor stages is adapted to pressurize the first refrigerant; And a second cooling loop adapted to circulate the second refrigerant therethrough, wherein the at least one second compressor stage of the plurality of compressor stages is adapted to pressurize the second refrigerant.

According to another aspect, a method of liquefying natural gas is provided. The method comprises the steps of: providing an integrated-gear turbo-compressor having a plurality of compressor stages; Driving the compressor as a prime mover; Circulating a first refrigerant through at least one first compressor stage of the plurality of compressor stages; Circulating a second refrigerant through at least one second compressor stage of the plurality of compressor stages; Cooling at least one of the natural gas and the second refrigerant by heat exchanging for the first refrigerant; And cooling the natural gas by heat exchanging for the second refrigerant.

Further aspects, advantages, and features of the disclosure will be apparent from the dependent claims, the description, and the accompanying drawings.

In such a way that the above-cited features of the present disclosure can be understood in detail, a more specific description of the disclosure briefly summarized above can be made with reference to the embodiments. The accompanying drawings relate to embodiments of the present disclosure and are described below. Some embodiments are depicted in the drawings and are described in detail in the description that follows.
1 is a schematic of an exemplary APCI process for liquefying natural gas;
2 is a schematic diagram of a natural gas liquefaction system according to an embodiment described herein;
3 is a schematic diagram of a natural gas liquefaction system according to a further embodiment described herein;
4 is an enlarged schematic diagram of a compressor arrangement for a natural gas liquefaction system in accordance with an embodiment described herein;
5 is a schematic diagram of a natural gas liquefaction system according to a further embodiment described herein; And
6 is a flow diagram illustrating a method of liquefying natural gas in accordance with an embodiment described herein.

Reference will now be made in detail to various implementations of the disclosure, one or more examples of which are illustrated in the drawings. Each example is provided for illustrative purposes and is not meant to be limiting. For example, a feature illustrated or described as part of one embodiment may be used with or in conjunction with any other embodiment to create further embodiments. This disclosure is intended to cover such modifications and variations.

Within the description of the following figures, like reference numerals refer to corresponding or similar components. In general, only differences relating to the individual embodiments are described. Unless otherwise stated, descriptions of parts or aspects in one embodiment also apply to corresponding parts or aspects in another embodiment.

1 shows a schematic diagram of a typical natural gas liquefaction system using a so-called APCI process. The process shown uses two refrigeration cycles. The pre-cooling cycle 12 uses the first refrigerant and the cooling cycle 2 uses the second refrigerant.

The system, indicated as 1 overall, comprises a cooling cycle 2 comprising a line formed by a gas turbine 3 driving a compressor train. The compressor train comprises a first compressor 5 and a second compressor 7 in series to compress the second refrigerant. The inter-stage cooler 9 may be provided to cool the second refrigerant delivered by the first compressor 5 to reduce the temperature and volume of the second refrigerant before entering the second compressor 7. The compressed second refrigerant delivered by the second compressor 7 can be condensed with respect to air or water in the second condenser 11. The second refrigerant is cooled and partially liquefied by heat exchange with respect to the first refrigerant circulating in the pre-cooling cycle 12.

The pre-cooling cycle 12 comprises a line comprising a gas turbine 13 which drives the compressor 15. The compressed first refrigerant delivered by the compressor 15 is condensed with respect to water or air in the first condenser 17. The condensed first refrigerant is used to pre-cool the natural gas to −40 ° C. and to cool and partially liquefy the second refrigerant. The pre-cooling of the natural gas and the partial liquefaction of the second refrigerant are carried out in a multi-pressure process, for example the four pressure process in the example shown in FIG. 1.

The stream of first refrigerant condensed from the first condenser 17 comprises a first set of four series arranged auxiliary heat exchangers for cooling and partially liquefying the second refrigerant, and 4 for pre-cooling the natural gas. To a second set of two series-arranged pre-cooled heat exchangers. The first portion of the compressed first refrigerant flowing from the first condenser 17 is passed through a pipe 19 to the first set of heat exchangers and in the sequentially arranged expanders 21, 23, 25 and 27. Inflate to four different, slowly decreasing pressure levels. A portion of the expanded first refrigerant, downstream from each expander, is converted to each heat exchanger 29, 31, 33, and 35.

The compressed second refrigerant delivered from the second condenser 11 can flow towards the main cryogenic heat exchanger 38 in the pipe 37. Pipe 37 passes sequentially through heat exchangers 29, 31, 33 and 35 such that the second refrigerant is slowly cooled and partially liquefied with respect to the expanded first refrigerant.

The second fraction of the first refrigerant condensed from the first condenser 17 is transferred to the second pipe 39 and expanded in four serially arranged expanders 41, 43, 45, and 47. A portion of the expanded first refrigerant at each expander is diverted towards the corresponding pre-cooling heat exchangers 49, 51, 53 and 55, respectively. Main natural gas line 61 flows sequentially through the pre-cooling heat exchangers 49, 51, 53 and 55 such that natural gas is pre-cooled before entering the main cryogenic heat exchanger 38. The heated first refrigerant exiting the pre-cooling heat exchangers 49, 51, 53, and 55 is collected together with the first refrigerant exiting the heat exchangers 29, 31, 33, and 35, and into the compressor 15. It is fed back to recover four evaporated streams of the first refrigerant and re-compress the vapor.

The system shown in FIG. 1 has at least one compressor driven by a gas turbine 13 for compressing a first refrigerant and at least one further compressor driven by a gas turbine 3 for compressing a second refrigerant. Include. Thus, the energy-efficiency of the system shown in FIG. 1 is limited and the two gas turbines 3, 13 take up a significant amount of space.

A natural gas liquefaction system 100 according to the embodiments described herein is schematically illustrated in FIG. 2.

The natural gas liquefaction system 100 is an integrated-gear turbo-compressor 150 having a plurality of compressor stages configured to be driven by a prime mover 160, in particular by a single prime mover such as an internal combustion engine or an electric motor (also simply a compressor ( 150). In other words, each compressor stage of the plurality of compressor stages of compressor 150 may be driven directly or indirectly by prime mover 160. A plurality of compressors 150 such that the transmission mechanism 301, in particular the gears of the compressor comprising one or more gear wheels, and / or other transmission units, such as pinions, pulleys, cogs, etc., drive the plurality of compressor stages in rotation. Can be connected between the compressor stages. Drive force may be provided by prime mover 160, for example via a main drive shaft connected to an integrated-gear turbo compressor.

By providing a compressor with integrated gears, the speed, torque and / or direction of the rotational force provided by the prime mover can be varied as appropriate. For example, the rotational speed and / or torque of the impellers of the plurality of compressor stages can be adjusted individually as appropriate. In some embodiments, the transmission mechanism can include a gear train or transmission. The impeller of the compressor stage can be mounted on each axis, which can be driven in rotation by one of the transmission elements of the gear. For example, the gear may include at least one gear wheel capable of rotationally driving one or more axes. The pinion can be mounted on each axis that can engage at least one gear wheel. In addition, one or two impellers of the plurality of compressor stages may be mounted on each axis.

In an integrated-gear compressor, at least one or more transmission units such as one or more gearwheels are connected between at least some of the plurality of compressor stages such that each impeller of the compressor stage can be rotated at different rotational speeds. When a gear or another force transmission mechanism is connected between at least some compressor stages, the compressor stage may be provided on different axes, which may be adapted to rotate at different rotational speeds. For example, the impeller of the one or more first compressor stages may be rotated at a different rotational speed than the impeller of the one or more second compressor stages.

For example, in some embodiments, one or more force transmission elements such as one or more central gearwheels may be provided to drive one or more first compressor stages and one or more second compressor stages at different rotational speeds. . The one or more first compressor stages may be provided on a different axis than the one or more second compressor stages.

In some embodiments, which can be combined with other embodiments described herein, the force transmission element, such as one or more center gearwheels, can be configured to drive two or more first compressor stages at different rotational speeds. . In some embodiments, which can be combined with other embodiments described herein, the force transmission element, such as one or more center gearwheels, can be configured to drive two or more second compressor stages at different rotational speeds. . In some implementations, the integrated-gear compressor can include a plurality of force transmission elements such as a plurality of central gearwheels to drive each stage of the plurality of compressor stages at a desired rotational speed.

As further depicted in FIG. 2, the natural gas liquefaction system 100 is a pre-cooling loop 110 adapted to circulate a first refrigerant therethrough, wherein the one or more first compressor stages of the plurality of compressor stages. A pre-cooling loop adapted to pressurize said first refrigerant, and a cooling loop 130 adapted to circulate therethrough said second refrigerant, wherein at least one second compressor stage of the plurality of compressor stages ( 155 includes a cooling loop adapted to pressurize the second refrigerant.

Each compressor stage of the plurality of first and second compressor stages may include a gas inlet, a gas outlet, and at least one impeller rotating on each axis. The compressor stage can be an axial or radial compressor stage.

The one or more first compressor stages 151 for pressurizing the first refrigerant may also be driven directly or indirectly by the prime mover 160, for example via a transmission mechanism or gear of the compressor. The one or more second compressor stages 155 for pressurizing the second refrigerant may also be driven directly or indirectly by the prime mover 160, for example via a transmission mechanism or gear of the compressor 150.

According to the embodiments described herein, a single integrated-gear multistage compressor driven by prime mover 160 has two or more cooling loops, for example pre-cooling loop 110 and cooling loop 130. It may be provided to pressurize two or more refrigerants circulating in. In some embodiments, the entire LNG liquefaction system may include a single integrated-gear compressor configured to pressurize two or more refrigerants used to liquefy natural gas.

The first compressor stage and the second compressor stage of the compressor may be housed in a single compressor casing, for example in a compact and space-saving manner. For example, the wall of the compressor housing surrounds the first plural compressor stages, the second plural compressor stages, as well as the transmission elements of the gears of the compressor that connect the drive shafts of the compressor stages with each other.

By using an integrated-gear multistage compressor to pressurize two, three or more refrigerants in the LNG liquefaction system, energy and space can be saved compared to previously used systems including one or more separate compressors. Can be. Since the plurality of compressor stages are strongly connected by the integrated gear of the compressor, adjustment of the rotational speed of the compressor stage may still be possible.

As further shown in FIG. 2, the natural gas liquefaction system 100 is configured to transfer heat from natural gas to a first refrigerant and / or from a second refrigerant to a first refrigerant 170. And a second heat exchanger device 180 for transferring heat from natural gas to the second refrigerant.

In some embodiments, the natural gas is adapted to be sequentially cooled by the first refrigerant and the second refrigerant. The natural gas is one or more first rows of the first heat exchanger device 170 in which the natural gas may be pre-cooled by the first refrigerant, for example below 0 ° C., in particular below -40 ° C. or below. It can be derived through the exchanger. Natural gas may subsequently be led through the second heat exchanger device 180, where the natural gas is cooled by the second refrigerant. The second heat exchanger device 180 may be the primary cryogenic heat exchanger of the system configured to cool the natural gas below the liquefaction temperature.

In the schematic diagram of FIG. 2, the second heat exchanger device 180 is a device that removes heat from natural gas flowing through the main natural gas line 61 and transfers heat to a second refrigerant flowing through the cooling loop 130. It is depicted in a simplified way.

The first refrigerant circulating in the pre-cooling loop 110 may be used to pre-cool the natural gas at the location of the main natural gas line 61 upstream from the second heat exchanger device 180. Alternatively or in addition, the first refrigerant may be used to cool the second refrigerant at the location of the cooling loop 130 upstream from the second heat exchanger device 180.

In the embodiment depicted in FIG. 2, the first heat exchanger device 170 includes a heat exchanger configured to pre-cool the natural gas and an additional heat exchanger configured to cool the second refrigerant. The first refrigerant leaving first heat exchanger device 170 may be directed back to compressor 150 to be re-compressed in one or more first compressor stages 151 of the compressor.

In some implementations, the second refrigerant leaving second heat exchanger device 180 can be directed back to compressor 150 to be re-compressed in one or more second compressor stages 155 of the compressor.

In some embodiments that can be combined with other embodiments described herein, the pre-cooling loop 110 includes a first condenser 17 for removing heat from the first refrigerant after compression. The pre-cooling loop may further include at least one expansion element (not shown in FIG. 2) for expanding the first refrigerant upstream from the first heat exchanger device 170.

The cooling loop 130 includes a second condenser 11 for removing heat from the second refrigerant after compression.

In some embodiments that can be combined with other embodiments described herein, the first refrigerant comprises a gas having a molecular weight of at least 35, in particular at least 40, more particularly propane.

In some embodiments that may be combined with other embodiments described herein, the second refrigerant is a mixed refrigerant, which may include a mixture comprising at least one of nitrogen, methane, ethane, and propane.

In some embodiments that can be combined with other embodiments described herein, at least one compressor stage of the plurality of compressor stages is provided with a movable inlet guide vane for autonomously regulating the flow into the at least one compressor stage. do. For example, each of the one or more first compressor stages 151 may be provided with respective movable inlet guide vanes.

As schematically depicted in FIG. 2, a single prime mover may be provided to drive each of the one or more first and second compressor stages. In some implementations, prime mover 160 may be or include a gas turbine and / or a motor, such as an electric motor or an internal combustion engine. One or more gear box elements of the integrated-gear turbo compressor may be connected between the prime mover, one or more first compressor stages and / or one or more second compressor stages. For example, at least some of the impellers of the one or more first compressor stages may rotate at different rotational speeds and may be provided on a different rotation axis than at least some of the impellers of the one or more second compressor stages.

A natural gas liquefaction system 200 according to the embodiments described herein is schematically illustrated in FIG. 3. The basic configuration of the natural gas liquefaction system 200 is similar to the system shown in FIG.

Natural gas liquefaction system 200 includes an integrated-gear turbo-compressor 150 having a plurality of compressor stages configured to be driven by prime mover 160, in particular by a single prime mover such as a gas turbine or another internal combustion engine. . In other words, each compressor stage of the plurality of compressor stages of compressor 150 may be driven directly or indirectly by prime mover 160. For example, a plurality of compressors of the compressor 150 such that the transmission mechanism, in particular the gears of the compressor having a plurality of gear wheels, and / or other transmission units, such as pinions, or pulleys, drive the plurality of compressor stages at a suitable rotational speed. It may be connected between the stage and the prime mover 160.

In some implementations, the compressor 150 includes a plurality of first compressor stages 151 configured to compress the first refrigerant circulating in the pre-cooling loop 110. For example, four first compressor stages may be provided. In other embodiments, different numbers of first compressor stages may be provided, for example two, three, or more than four first compressor stages.

The plurality of first compressor stages 151 may be arranged sequentially in a pre-cooling loop. For example, a first refrigerant entering the compressor 150 in an initial first compressor stage may be transferred to the other first compressor stage (s) arranged by the initial first compressor stage and downstream from the initial first compressor stage. Subsequently pressurized. The pressure of the first refrigerant may be increased in each of the first compressor stages 151 arranged sequentially.

In some embodiments that can be combined with other embodiments described herein, the compressor 150 can include a plurality of second compressor stages 155 configured to pressurize a second refrigerant circulating in the cooling loop 130. Can be. For example, two, three, four or more second compressor stages 155 may be provided. The second compressor stage 155 may be arranged sequentially in the cooling loop. In other words, the second refrigerant entering the compressor 150 in the initial second compressor stage is transferred to the further second compressor stage (s) arranged by the initial second compressor stage and downstream from the initial second compressor stage. Subsequently pressurized. The pressure of the second refrigerant may be increased by each of the second compressor stages 155 arranged sequentially. The impellers of the two or more second compressor stages may be mounted on different axes and in some embodiments may be rotated at different rotational speeds.

For example, compressor 150 may include four first compressor stages to compress the first refrigerant and three (or alternatively four) second compressor stages to compress the second refrigerant. .

In some implementations, pre-cooling loop 110 can be configured to split a first refrigerant into a plurality of precooling streams directed to each of the plurality of first compressor stages 151. The number of precooling streams may correspond to the number of first compressor stages. Each precooling stream is passed from the associated first compressor stage to the compressor by the associated first compressor stage and, if any, further recompressed by additional first compressor stage (s) arranged downstream thereof. It can flow in.

In some embodiments, the plurality of first expansion elements 241, 243, 245, 247 can be arranged sequentially in the pre-cooling loop 110 and configured to expand the first refrigerant at a plurality of decreasing pressure levels. Can be. The plurality of first heat exchangers 249, 251, 253, 255 of the first heat exchanger device 270 are expanded through at least one of the plurality of first expansion elements 241, 243, 245, 247. It may be provided to receive each precooled stream of one refrigerant and transfer heat from the natural gas to the first refrigerant.

A plurality of return paths 261, configured to return the precooled stream of first refrigerant from each of the plurality of first compressor stages 151 from a plurality of first heat exchangers 249, 251, 253, 255. 263, 265, 267 may be provided.

According to some embodiments, which can be combined with other embodiments described herein, at least one first auxiliary expansion element can be arranged in the precooling loop. In addition, at least one first auxiliary heat exchanger may be provided for receiving at least a portion of the first refrigerant expanded through at least one first auxiliary expansion element and transferring heat from the second refrigerant to the first refrigerant. .

According to some embodiments, which can be combined with other embodiments described herein, the system includes a plurality of systems arranged in sequence in the pre-cooling loop 110 and configured to expand the first refrigerant at a plurality of decreasing pressure levels. It may comprise a first secondary expansion element (221, 223, 225, 227). The plurality of first auxiliary heat exchangers 229, 231, 233, 235 of the first heat exchanger device 270 is expanded through at least one of the plurality of first auxiliary expansion elements 221, 223, 225, 227. It may be provided to receive each portion of the first refrigerant and to transfer heat from the second refrigerant to the first refrigerant.

A plurality of return paths 261, 263, 265, 267 are provided from the plurality of first auxiliary heat exchangers 229, 231, 233, 235 and / or from the first heat exchangers 249, 251, 253, 255. Each of the first compressor stages 151 may be configured to return the portion of the first refrigerant.

During operation of the natural gas liquefaction system 200, a stream of compressed first refrigerant may be transferred from the first compressor stage that is the most downstream of the plurality of first compressor stages 151 to the first condenser 17. The flow of the first refrigerant delivered through the first condenser 17 can, for example, be cooled against water or air and can be condensed.

In some embodiments, the condensed first refrigerant is circulated in the pre-cooling loop 110 to pre-cool the natural gas in the plurality of first heat exchangers 249, 251, 253, 255, and / or the plurality of The second refrigerant circulating in the cooling loop 130 in the first auxiliary heat exchanger 229, 231, 233, 235 is cooled and optionally partially liquefied.

In some embodiments, pre-cooling loop 110 may be divided into a plurality of n pressure levels, for example four pressure levels. The number n of pressure levels may correspond to the number n of first compressor stages of the compressor 150 configured for compressing the first refrigerant. The flow of the first refrigerant delivered through the first condenser 17 can be sequentially expanded at n progressively decreasing pressure levels and divided into n partial flows. Each partial flow of the first refrigerant may be returned to the side flow from the corresponding one inlet of the plurality of first compressor stages 151 to the compressor 150.

The first delivery line 217 can deliver the first portion of the condensed first refrigerant stream to the plurality of first expansion elements 241, 243, 245, 247. The second delivery line 218 branched from the first delivery line 217 may deliver a second portion of the condensed first refrigerant flow to the plurality of first auxiliary expansion elements 221, 223, 225, 227.

The first portion of the first refrigerant condensed from the first condenser 17 may be sequentially expanded in the plurality of first expansion elements 241, 243, 245, 247 at n different, slowly decreasing pressure levels. A portion of the flow of partially expanded first refrigerant, downstream from each first expansion element, may be converted to each of the plurality of first heat exchangers 249, 251, 253, 255. The remaining portion of the partially expanded first refrigerant may be caused to flow through the next first expansion element or the like. The remaining first refrigerant flowing through the most downstream of the plurality of first expansion elements 241, 243, 245, 247 is the most of the plurality of first heat exchangers 249, 251, 253, 255. May be passed to 255 downstream.

In each of the plurality of first heat exchangers 249, 251, 253, 255, the first refrigerant can exchange heat for natural gas flowing in the main natural gas line 61, thus pre-loading the natural gas. Cool and optionally partially liquefy.

The second portion of the condensed first refrigerant expanded in at least one of the plurality of first auxiliary expansion elements 221, 223, 225, 227 corresponds to one of the plurality of first auxiliary heat exchangers 229, 231, 233, 235. Can be turned towards doing. The portion of the first refrigerant conveyed by each of the plurality of first auxiliary expansion elements 221, 223, 225, 227 and not caused to flow through each first auxiliary heat exchanger is the plurality of first auxiliary expansion elements. And subsequent to 221, 223, 225, 227. The downstream of the plurality of first auxiliary heat exchangers 229, 231, 233, 235 is the downstream of the plurality of first auxiliary expansion elements 221, 223, 225, 227 ( The remaining fraction of the first refrigerant expanded at 227. In each of the first auxiliary heat exchangers, the first refrigerant exchanges heat for the second refrigerant circulating in the cooling loop 130, and thus the first of the plurality of first auxiliary heat exchangers 229, 231, 233, 235. In terms of delivery 235 downstream, the second refrigerant is cooled and optionally at least partially liquefied.

The heated first refrigerant from the plurality of first heat exchangers 249, 251, 253, 255 may be collected with the heated first refrigerant from the first auxiliary heat exchangers 229, 231, 233, 235, respectively. Can be fed back to the integrated-gear turbo-compressor 150 at the inlet of the first compressor stage.

In some embodiments, the heated first refrigerant from one of the plurality of first auxiliary heat exchangers 229, 231, 233, 235 is a corresponding one of the plurality of first heat exchangers 249, 251, 253, 255. At approximately the same pressure as the heated first refrigerant from. The first refrigerant collected at the corresponding pressure level may be delivered at the inlet of the corresponding stage of the plurality of first compressor stages of the compressor 150. The plurality of side streams of the first refrigerant are thus returned at a gradually decreasing pressure level at the inlets of the first compressor stage 151 arranged sequentially.

In some embodiments, the plurality of return paths 261, 263, 265, 267 are from a plurality of first heat exchangers 249, 251, 253, 255 and / or a plurality of first auxiliary heat exchangers 229, 231, 233, 235 may be configured to deliver a side stream of expanded and spent first refrigerant to corresponding stages of the plurality of first compressor stages 151.

In some embodiments that can be combined with other embodiments described herein, the second refrigerant circulating in the cooling loop 130 may be arranged in a plurality of second compressor stages 155 sequentially in the cooling loop 130. Can be compressed by. The plurality of second compressor stages 155 is part of the same integrated-gear compressor as the plurality of first compressor stages 151.

In some embodiments, the integrated-gear compressor can include at least one multistage compressor unit, for example a multistage centrifugal compressor unit, having two or more compressor stages arranged sequentially on a single axis.

The prime mover 160 for driving the compressor may comprise an internal combustion engine or an electric motor. The prime mover 160 may be a gas turbine, for example an air induction gas turbine.

In some implementations, at least one first internal cooler can be arranged between at least two sequentially arranged first compressor stages of the plurality of first compressor stages 151. In some implementations, at least one second internal cooler can be arranged between at least two sequentially arranged second compressor stages of the plurality of second compressor stages 155. The internal cooler may be configured to reduce the temperature and volume of each refrigerant delivered by each compressor stage prior to introduction to a subsequent compressor stage or before leaving the compressor.

The second refrigerant delivered by being the most downstream of the plurality of second compressor stages 155 may be condensed by the second condenser 11. The second condenser 11 may be an air condenser of a water condenser, where the second refrigerant may be condensed by exchanging heat for air or water. The condensed second refrigerant may subsequently be delivered by a delivery line through a plurality of first auxiliary heat exchangers 229, 231, 233, 235, where the second refrigerant is a pre-cooling loop ( Cooling and optionally liquefying may be accomplished by exchanging heat for the first refrigerant circulating in 110.

The cooled second refrigerant delivered from the plurality of first auxiliary heat exchangers may be directed towards a second heat exchanger device 180 which may be the primary cryogenic heat exchanger, where the second refrigerant is from pre-cooled natural gas. Further heat can be removed to achieve the liquefaction process. The heated second refrigerant may be returned via return line 269 to one of the plurality of second compressor stages 155 of compressor 150.

In FIG. 3, a plurality of compressor stages of the integrated-gear turbo-compressor 150 are only depicted in a schematic manner. Compressor 150 of an exemplary embodiment is illustrated in more detail in FIG. 4.

4 is an enlarged schematic diagram of a compressor arrangement having an integrated-gear turbo-compressor 150 in accordance with an embodiment described herein. Compressor 150 may include a plurality of compressor stages that may be driven by prime mover 160 and directly or indirectly by prime mover 160. The plurality of compressor stages include one or more first compressor stage 151 for compressing the first refrigerant circulating in the pre-cooling loop 110 and one for compressing the second refrigerant circulating in the cooling loop 130. The above second compressor stage 155 is included. Details of the pre-cooling loop 110 and the cooling loop 130 are described above in connection with FIGS. 2 and 3 and are not repeated here.

The compressor 150 may be arranged in the compressor housing 330 and may include a transmission mechanism 301, for example an integrated gear, which may be configured to be driven by the prime mover 160. The compressor 150 may further include at least one first shaft 303 configured to be driven in rotation by the transfer mechanism 301 and configured to drive at least one of the plurality of first compressor stages 151. Can be. In other words, the impeller of the at least one first compressor stage may be mounted on at least one first axis 303 as for rotating with the first axis. In addition, compressor 150 may include at least one second shaft 305 configured to be driven in rotation by the transfer mechanism 301 and configured to drive at least one of the plurality of second compressor stages 155. Can be. There, the impeller of the at least one second compressor stage can be mounted on at least one second shaft 305 as to rotate with the second shaft.

In some implementations, the at least one first shaft 303 can drive two first compressor stages, eg, two subsequent first compressor stages of the plurality of first compressor stages. Alternatively or in addition, the at least one second shaft 305 can drive two second compressor stages of the plurality of second compressor stages, for example two subsequent second compressor stages.

In some embodiments, at least one first shaft 303 may be provided with a pinion that engages with the gear wheel of the transmission mechanism 301, and / or the at least one second shaft 305 may have a transmission mechanism 301. An additional pinion can be provided which engages with the gear wheel. For example, in some implementations, the transmission mechanism 301 is configured to drive the first gear wheel 307 and the at least one second shaft 305 configured to drive at least one first axis 303. It may comprise a second gear wheel 308 configured.

Alternatively, in the embodiment schematically depicted in FIG. 5, for example, the transfer mechanism 301 drives at least one first axis 303 and drives at least one second axis 305. It may comprise one central gear wheel 307 configured. For example, a single male gear may be provided configured to drive (eg, directly) each of the first and second compressor stages.

In other words, a first pinion having a first diameter may be connected to at least one first axis 303 and / or a second pinion having a second diameter may be connected to at least one second axis 305. . The center gear wheel 307 of the gear may directly engage the first and second pinions for driving the at least one first axis and the at least one second axis in rotation. In the embodiment depicted in FIG. 5, the center gear wheel 307 is directly in contact with respective pinions connected to two or more first axes 303 and two or more second axes 305. To interlock. For example, a (single) center gear wheel can directly drive the axes of three, four or more first compressor stages and three, four or more second compressor stages.

The first diameter of the first pinion may correspond to the second diameter of the second pinion. Thus, the first axis and the second axis can rotate at a corresponding rotational speed. Alternatively, the first diameter and the second diameter can be different. Thus, the rotational speeds of the first and second axes can be adjusted differently as appropriate. For example, the rotational speeds of the first and second compressor stages can be adapted to the characteristics of each refrigerant derived through it.

In alternative implementations, two or more male gears may be provided to drive the plurality of compressor stages. For example, the first male gear can drive one or more first compressor stages, and the second male gear can drive one or more second compressor stages.

In some implementations, it is recognized that at least one first axis and / or at least one second axis can drive two compressor stages that can be arranged on opposite ends of each axis. In Figures 3 and 5, the two compressor stages provided on a single shaft are schematically illustrated by two oppositely oriented arrow heads connected by connecting lines showing a common axis. For example, the first impeller of one compressor stage may be mounted on the first part of the common axis and the second impeller of the further compressor stage may be mounted on the second part of the common axis.

Referring again to FIGS. 3 and 4, in some embodiments that can be combined with other embodiments described herein, the first gear wheel 307 can drive a plurality of first compressor stages 151 and The second gear wheel 308 may drive the plurality of second compressor stages 155. The gear wheels may each be toothed wheels driven in rotation directly or indirectly by prime mover 160. The first and second shafts may each include pinions mounted thereon and engaging respective toothed wheels. The first and second shafts and the impeller (s) mounted on the shafts can thus rotate at different rotational speeds.

The diameter of the second gear wheel 308 may be smaller than the diameter of the first gear wheel 307. When the first gear wheel 307 is directly engaged with the second gear wheel 308, the second gear wheel 308 can rotate at a higher rotational speed than the first gear wheel 307. Thus, the at least one second shaft 305 driven by the two gear wheels 308 can be rotated at a higher rotational speed than the at least one first shaft 303 driven by the first gear wheel 307. Can be. Thus, the impeller (s) of the first compressor stage (s) mounted on the at least one first shaft 303 are impellers of the second compressor stage (s) mounted on the at least one second shaft 305. Can be rotated at a higher rotational speed.

In some implementations that can be combined with other embodiments described herein, the compressor can include two or more first shafts that drive the plurality of first compressor stages 151, where the two or The further first shaft can be driven by the first gear wheel 307. The at least one first shaft may be configured to drive two sequentially arranged first compressor stages. Alternatively or in addition, the at least one first shaft may be configured to drive a single first compressor stage. In the latter case, the impeller of the single first compressor stage may be mounted on the first axis.

In some implementations that can be combined with other embodiments described herein, the compressor can include two or more second shafts that drive a plurality of second compressor stages 155, wherein the two or The further second shaft can be driven by the second gear wheel 308. The at least one second shaft may be configured to drive two sequentially arranged second compressor stages. Alternatively or in addition, the at least one second shaft may be configured to drive a single of the plurality of second compressor stages.

Each compressor stage of the plurality of compressor stages may include a gas inlet, a gas outlet, and at least one impeller mounted on each axis. Each impeller may be a radial impeller having an axial inlet and a radial outlet. The fluid processed through the impeller may be collected in each vortex chamber of the compressor stage. The impellers can be paired, where a pair of impellers (eg belonging to two subsequent compressor stages) can be mounted on a common axis of rotation.

In some embodiments, the plurality of first compressor stages 151 are pressures in which the pressurized first refrigerant is in the range of 10 bar to 40 bar absolute, in particular 20 bar to 30 bar absolute, more specifically 22 bar to 24 bar absolute. And may compress the first refrigerant to be delivered from the first compressor stage 312 which is the most downstream of the plurality of first compressor stages 151. The pressure of the first refrigerant at the inlet of the first compressor stage 315 most upstream may be between 1 bar absolute and 2 bar absolute in some embodiments.

Alternatively or additionally, the plurality of first compressor stages 151 may comprise a first compressor that is the most downstream of the plurality of first compressor stages 151 at a temperature in which the pressurized first refrigerant ranges from 60 ° C. to 100 ° C. Can be configured to compress the first refrigerant to be delivered from the stage 312, in particular the temperature ranges from 75 ° C. to 85 ° C. For example, an inter-cooling stage may not be provided between two first compressor stages.

In some embodiments, the at least one first shaft 303 on which the one or more impellers of the one or more first compressor stages 151 are mounted may range from 3.000 rpm (rpm) to 7.000 rpm, in particular from about 4.000 rpm to about It can be configured to rotate at a rotation speed of 5.500 rpm. In some embodiments, two or more first axes may be provided in which the impellers of all first compressor stages are mounted thereon. Each first axis may be configured to rotate at a rotational speed of 3000 rpm to about 7000 rpm. The axis of the first compressor stage most upstream may rotate at a lower speed than the axis of the first compressor stage most downstream.

The plurality of first compressor stages 151 may deliver the first refrigerant compressed at a flow rate ranging from about 10,000 actual m³ / h to about 70,000 actual m³ / h.

The plurality of first compressor stages 151 may absorb power in the range of about 10 MW to about 40 MW, in particular in the range of about 25 MW to about 35 MW. Alternatively or in addition, the plurality of second compressor stages 155 may absorb power in the range of about 10 MW to about 40 MW, in particular in the range of about 25 MW to about 35 MW. Thus, in some embodiments, prime mover 160 may provide power in the range of 20 kW to 80 kWMW, in particular 50 kW to 70 kW.

In some embodiments, the plurality of second compressor stages 155 may include one of the plurality of second compressor stages 155 at a pressure in which the pressurized second refrigerant is in the range of 50 bar to 100 bar absolute, in particular 55 bar to 65 bar absolute. And may compress the second refrigerant to be delivered from the second compressor stage 316 which is downstream. The pressure of the second refrigerant at the inlet of the second compressor stage 319 most upstream may be below 10 kPa absolute pressure in some embodiments.

In some embodiments, the plurality of second compressor stages 155 is the most down of the plurality of second compressor stages 155 at temperatures in which the pressurized second refrigerant ranges from 60 ° C. to 120 ° C., in particular from 80 ° C. to 100 ° C. And may compress the second refrigerant to be delivered from the second compressor stage 316, which is a stream. For example, one, two or more inter-cooling stages 320 may be provided between at least two subsequent second compressor stages. Thus, the outlet temperature of the second refrigerant can be reduced.

The at least one second shaft 305 on which the impeller (s) of the one or more second compressor stages are mounted may be configured to rotate at a rotational speed of 7.000 rpm to 20.000 rpm, in particular 8.000 rpm to about 15.000 rpm. . In some implementations, two or more second shafts may be provided to drive the impellers of all second compressor stages 155. The axis of the second upstream compressor stage 319 is lower than the axis of the second downstream compressor stage 316 (eg, speed between 14.000 rpm and 16.000 rpm) (eg 9.000 rpm to 11.000 rpm). Can be rotated).

4 shows an exemplary embodiment in which a plurality of first compressor stages 151 comprises a total of four subsequently arranged first compressor stages. The upstream pair of first compressor stages is driven by a rotational axis, and the downstream pair of first compressor stages is driven by an additional rotational axis, where both rotational axes are driven by the first gear wheel 307. In other words, the impellers of the upstream pair of first compressor stages are mounted on a common axis of rotation, and the impellers of downstream pairs of the first compressor stage are mounted on a further common axis of rotation. Alternatively, only upstream pairs of the first compressor stage may be driven by a common axis of rotation, while the two downstream first compressor stages may each be driven by separate axis of rotation, or vice versa. Can be.

In the exemplary embodiment of FIG. 4, the plurality of second compressor stages 155 includes a total of four subsequently arranged second compressor stages. The upstream pair of second compressor stages is driven by a rotational axis, and the downstream pair of second compressor stages is driven by an additional rotational axis, where both rotational axes are driven by a second gear wheel 308. In other words, the impeller of the upstream pair of the second compressor stage is mounted on a common axis of rotation, and the impeller of the downstream pair of the second compressor stage is mounted on a further common axis of rotation. Alternatively, only three subsequently arranged second compressor stages can be provided wherein the upstream pair of second compressor stages can be driven by a common axis of rotation, and the downstream second compressor stage is a separate It can be driven by the axis of rotation, or vice versa.

Other possible arrangements and number of first and second compressor stages on each axis of rotation driven in rotation by the transmission mechanism or gears of the compressor will be apparent to the skilled person.

According to a further aspect, a compressor arrangement for compressing a plurality of refrigerants is provided. The compressor arrangement includes an integrated-gear turbo-compressor 150 having a plurality of compressor stages that may have some or all of the features of the compressor described above.

The compressor arrangement may comprise a first cooling line, for example a first cooling line that is part of a pre-cooling loop, adapted to flow therethrough, wherein at least one first compressor of the plurality of compressor stages. The stage is adapted to pressurize the first refrigerant flowing through the first cooling line. The compressor arrangement may comprise a second cooling line, for example a second cooling line that is part of a cooling loop adapted to flow therethrough, wherein the one or more second compressor stages of the plurality of compressor stages are It is adapted to pressurize the second refrigerant flowing through the second cooling line.

The compressor arrangement can be used in natural gas liquefaction systems according to any of the embodiments described above.

The compressor arrangement may include a transmission mechanism or gear having some or all of the features of the embodiments described above. In addition, all compressor stages may be included in a single housing in some embodiments.

According to a further aspect described herein, a method of liquefying natural gas is provided. The flow diagram of the method according to the embodiments described herein is schematically depicted in FIG. 6.

In box 710, an integrated-gear turbo compressor having a plurality of compressor stages is provided. In box 720, the compressor is driven by the prime mover. In box 730, the first refrigerant is circulated through one or more first compressor stages of the plurality of compressor stages, and the second refrigerant is circulated through one or more second compressor stages of the plurality of compressor stages. In box 740, at least one of the natural gas and the second refrigerant is cooled by heat exchange for the first refrigerant. In box 750, the natural gas is cooled by heat exchange for a second refrigerant.

In some embodiments, the compressed first refrigerant and / or the compressed second refrigerant can be condensed. The condensed first refrigerant may be expanded, for example, in a plurality of sequentially arranged first expansion elements.

In some embodiments, the first refrigerant can be divided into a plurality of partial flows.

In some embodiments, at least a portion of the first refrigerant may be sequentially compressed by a plurality of first compressor stages, for example three, four or more first compressor stages, and / or a second refrigerant Can be sequentially compressed by a plurality of second compressor stages, for example three, four or more second compressor stages.

A movable inlet guide vane may be provided at the inlet of at least one of the plurality of first compressor stages. The movable inlet guide vanes can be individually controlled to regulate the partial flow at the suction side of the plurality of first compressor stages, in particular as a function of the flow conditions of the partial flow.

In some embodiments, the method can further include: expanding the first refrigerant through the plurality of sequentially arranged first expansion elements at a plurality of decreasing pressure levels; Circulating a portion of the expanded first refrigerant from the first expansion element through the plurality of first heat exchangers to remove heat from the natural gas; And returning a portion of the expanded first refrigerant from the plurality of first heat exchangers to each of the one or more first compressor stages.

In some embodiments, the method can further include: expanding the first refrigerant through the plurality of sequentially arranged first auxiliary expansion elements at a plurality of decreasing pressure levels; Circulating a portion of the expanded first refrigerant through the plurality of first auxiliary heat exchangers to remove heat from the second refrigerant; And returning a portion of the first refrigerant from the plurality of first auxiliary heat exchangers to each of the one or more first compressor stages.

The prime mover may drive a transmission mechanism of the compressor, for example an internal gear, wherein the transmission mechanism may drive at least one first axis and at least one second axis in rotation.

At least one first axis may be driven in rotation at a rotational speed of 3.000 rpm or more and 7.000 rpm or less by the transfer mechanism. The impellers of one or two first compressor stages may be mounted on at least one first axis and may rotate at a rotational speed of at least one axis.

At least one second shaft may be driven in rotation at a rotational speed of 8.000 rpm or more and 15.000 rpm or less by the transfer mechanism and may drive at least one of the second compressor stages. In other words, the impeller of the at least one second compressor stage may be mounted on at least one second shaft.

In some embodiments, the first refrigerant may be sequentially circulated through three, four or more first compressor stages of the compressor and discharge in the range of absolute pressure 10 barbar to 40 barbar, in particular absolute bar 20 bar to 30 bar. Can be compressed to pressure.

In some embodiments, the second refrigerant can be sequentially circulated through three, four or more second compressor stages of the compressor and discharge in the range of 40 bar to 100 bar absolute, in particular 50 bar to 80 bar absolute. Can be compressed to pressure.

The use of an integrated-gear turbo-compressor to compress two or more different refrigerants circulating in two or more cooling loops can result in improved efficiency and thus reduced power consumption of the natural gas liquefaction system and This can additionally result in significant cost savings when compared to systems with two or more separate compressors and compressor drive units. In addition, the gears of the compressor can be adjusted so that each compressor stage can rotate at an appropriate rotational speed. The use of a single compressor unit in a natural gas liquefaction system is an advantage in terms of cost, footprint and flexibility.

The number of first and second compressor stages as well as the details of the internal gears of the compressor (eg the details of the transfer mechanism) may depend on the nature of the refrigerant being compressed. In addition, when three, four or more refrigerants are compressed by an integrated-gear compressor, larger or modified transfer mechanisms may be provided.

While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof, the scope of which is determined by the following claims. .

Claims (18)

An integrated-gear turbo-compressor 150 having a plurality of compressor stages;
A single prime mover (160) for driving the compressor (150);
This is a pre-cooling loop adapted to circulate a first refrigerant, wherein one or more first compressor stages 151 of the plurality of compressor stages are adapted to pressurize the first refrigerant 110. );
A cooling loop adapted to circulate a second refrigerant therethrough, wherein one or more second compressor stages 155 of the plurality of compressor stages are adapted to pressurize the second refrigerant;
A first heat exchanger device (170) for transferring heat from natural gas and / or from said second refrigerant to said first refrigerant; And
A second heat exchanger device 180 for transferring heat from natural gas to the second refrigerant,
Wherein the single prime mover (160) drives each of one or more first compressor stages (151) and second compressor stages (155). The compressor (150) of claim 1, wherein the compressor (150) compresses a plurality of first compressor stages (151), in particular four sequentially arranged first compressor stages, and / or the second refrigerant for compressing the first refrigerant. A plurality of second compressor stages (155), in particular three or four sequentially arranged second compressor stages. The system of claim 1 or 2, wherein the compressor 150 comprises:
A transmission mechanism (301), in particular comprising a gear, configured to be driven in rotation by the prime mover;
At least one first shaft 303 configured to be driven in rotation by the transfer mechanism 301 and configured to drive at least one of the first compressor stages; And
At least one second shaft (305) configured to be driven in rotation by the transfer mechanism (301) and configured to drive at least one of the second compressor stages. 4. The first gear wheel 307 of claim 3, wherein the transmission mechanism 301 is engaged with at least one first pinion connected to at least one first shaft 303 for driving at least one first compressor stage. Including, the system. The method of claim 3 or 4, wherein the first gear wheel 307 is further engaged with at least one second pinion connected to at least one second shaft 305 for driving at least one second compressor stage. system. The method of claim 3, wherein the transmission mechanism 301 comprises a first gear wheel 307 configured to drive at least one first shaft 303, and a first gear wheel configured to drive at least one second shaft 305. 2 gear wheels 308, in particular wherein the diameter of the second gear wheel 308 is smaller than the diameter of the first gear wheel 307 and / or the first gear wheel and the second gear wheel are connected to the gear wheel. Directly interlocked, system. The system of claim 3, wherein at least one of the at least one first axis and the at least one second axis drives two compressor stages arranged on opposite ends of each axis. 8. The compressor of claim 1, wherein the compressor 150 comprises a plurality of first compressor stages 151, and the pre-cooling loop 110 of the plurality of first compressor stages 151. And divide the first refrigerant into a plurality of precooling streams led to respective ones. The system of claim 8 comprising:
A plurality of first expansion elements (241, 243, 245, 247) sequentially arranged in the pre-cooling loop (110) and configured to expand the first refrigerant at a plurality of decreasing pressure levels;
A first row for receiving a respective precooling stream of the first refrigerant expanded through at least one of the plurality of first expansion elements 241, 243, 245, 247 and transferring heat from the natural gas to the first refrigerant A plurality of first heat exchangers 249, 251, 253, 255 of the exchanger devices 170, 270; And
A plurality of return paths 261 configured to return the precooled stream of first refrigerant from each of the plurality of first heat exchangers 249, 251, 253, 255 to each of the plurality of first compressor stages 151. 263, 265, 267). The method of claim 1, wherein at least one first auxiliary expansion element arranged in the pre-cooling loop 110 and a portion of the first refrigerant expanded through the at least one first auxiliary expansion element are received. And at least one first auxiliary heat exchanger of the first heat exchanger device (170, 270) configured to transfer heat from the second refrigerant to the first refrigerant. The system of claim 10, comprising:
A plurality of first auxiliary expansion elements 221, 223, 225, 227 arranged sequentially in the pre-cooling loop 110 and configured to expand the first refrigerant at a plurality of decreasing pressure levels;
A first configured to receive each portion of the first refrigerant expanded through at least one of the plurality of first auxiliary expansion elements 221, 223, 225, 227 and transfer heat from the second refrigerant to the first refrigerant A plurality of first auxiliary heat exchangers 229, 231, 233, 235 of one heat exchanger device 170, 270; And
A plurality of return paths 261, 263 configured to return the portion of the first refrigerant from each of the plurality of first compressor stages 151 from a plurality of first auxiliary heat exchangers 229, 231, 233, 235. , 265, 267). The method of claim 1, wherein the first refrigerant comprises a gas having a molecular weight of at least 40, in particular propane, and / or the second refrigerant is a mixed refrigerant, in particular methane, ethane, propane and / or A system, which is a mixture comprising nitrogen. The system of claim 1, wherein the prime mover comprises an electric motor or an internal combustion engine, in particular a gas turbine. A method of liquefying natural gas, comprising the following steps:
Providing an integrated-gear turbo-compressor 150 having a plurality of compressor stages;
Driving the compressor 150 with a single prime mover 160;
Circulating a first refrigerant through one or more first compressor stages 151 of a plurality of compressor stages, wherein each of the one or more first compressor stages 151 is driven by the single prime mover 160. , step;
Circulating a second refrigerant through one or more second compressor stages 155 of a plurality of compressor stages, wherein each of the one or more second compressor stages 155 is driven by the single prime mover 160. , step;
Cooling at least one of the natural gas and the second refrigerant by heat exchanging the first refrigerant; And
Cooling the natural gas by heat exchanging the second refrigerant. The method of claim 14, further comprising the following steps:
Expanding the first refrigerant through the plurality of sequentially arranged first expansion elements (241, 243, 245, 247) at a plurality of decreasing pressure levels;
Circulating a portion of the first refrigerant from the plurality of sequentially arranged first expansion elements through a plurality of first heat exchangers 249, 251, 253, 255 to remove heat from natural gas; And
Returning a portion of the first refrigerant from a plurality of first heat exchangers to each of the at least one first compressor stage. The method according to claim 14 or 15,
The delivery mechanism 301 of the compressor is driven by prime mover 160,
At least one first shaft 303 is driven in rotation by the transfer mechanism 301 at a rotational speed of 3.000 rpm or more and 7.000 rpm or less and drives at least one of the first compressor stages;
At least one second axis (305) is driven rotationally by the transfer mechanism (301) at a rotational speed of 8.000 rpm or more and 20.000 rpm or less and drives at least one of the second compressor stages. The method of claim 14, wherein the first refrigerant is sequentially circulated through three, four or more first compressor stages and compressed to discharge pressure in the range of 10 kPa to 40 kPa absolute pressure. And / or said second refrigerant is sequentially circulated through three, four or more second compressor stages and compressed to discharge pressure in the range of absolute pressure 50 barbar to 100 barbar. 18. The inlet guide vanes according to any one of claims 14 to 17, having independently movable inlet guide vanes for adjusting partial flow at the suction side of the at least one first compressor stage, in particular as a function of the flow conditions of each partial flow Further comprising the step of controlling.

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