KR101617177B1 - Method and apparatus for cooling and liquefying a hydrocarbon stream - Google Patents

Abstract

A method for driving two or more refrigerant compressors in a hydrocarbon cooling process. In such a hydrocarbon cooling process, the hydrocarbon feed stream 10 may be passed over some evaporated refrigerant stream. At least some evaporated refrigerant streams (35a, 37b) are compressed through refrigerant compressors (34, 36). One or more gas turbines 54 are driven to provide power 56 and hot gases. The hot gas 57 is passed through at least one steam heat exchanger 58 to provide steam power which is used to drive one or more steam turbines 82 such that at least one of the refrigerant compressors 34 . The power is used to drive at least one of the refrigerant compressors 36 (76).

Description

METHOD AND APPARATUS FOR COOLING AND LIQUEFYING A HYDROCARBON STREAM FIELD OF THE INVENTION [0001]

The present invention relates to a method for cooling and liquefying a hydrocarbon stream carried out in a floating vessel or off-shore platform and a floating vessel or off-shore platform comprising an apparatus for cooling and liquefying a hydrocarbon stream .

Typical hydrocarbon streams that are cooled and / or liquefied include natural gas or consist essentially of natural gas.

Various methods of liquefying a natural gas stream to obtain liquefied natural gas (LNG) are known. Liquefaction of the natural gas stream is desirable for a number of reasons. In one example, natural gas can be stored and transported over a distance as liquid rather than gas form, because it takes up a smaller volume and does not need to be stored at high pressure.

US 4,041,721 discloses a vessel with natural gas liquefaction capability. Which is formed from a plurality of self-contained liquefaction assemblies each disposed within a separate liquefaction compartment. The liquefaction assembly includes a compressor-driver assembly in which the gas turbine is in immediate proximity to the compressor. Thus, a gas turbine forms an ignition source near a hydrocarbon inventory, such as, for example, refrigerant.

The present invention seeks to eliminate or at least reduce the number of gas turbines near an important hydrocarbon inventory.

The invention relates to a method for cooling and liquefying a hydrocarbon stream in a floating vessel or on a floating platform,

(a) passing a hydrocarbon feed stream over two or more refrigerant streams to provide a cooled and liquefied hydrocarbon stream and at least a portion of two or more evaporated refrigerant streams;

(b) compressing at least one of the at least one evaporated refrigerant stream through at least one first refrigerant compressor;

(c) compressing at least one of the at least one evaporated refrigerant stream through at least one second refrigerant compressor;

(d) driving at least one gas turbine to provide (i) power and (ii) hot gas;

(e) passing the hot gas (ii) of step (d) through one or more steam heat exchangers to provide steam power;

(f) using the power to drive at least one of the second refrigerant compressors; And

(g) driving at least one of the first refrigerant compressors using the steam power to drive one or more steam turbines,

The method is carried out in a floating vessel or on a marine platform comprising one or more storage tanks for liquefied hydrocarbons and / or refrigerant components, wherein the one or more gas turbines are installed in or on the floating vessel or on the offshore platform, A method of cooling and liquefying a hydrocarbon stream that is driven in a turbine-assembly region located away from a refrigerant compressor and away from one or more storage tanks.

The invention also relates to a floating vessel or marine platform comprising an apparatus for cooling and liquefying a hydrocarbon stream on or in a floating vessel,

At least two cooling processes for passing a hydrocarbon feed stream over two or more refrigerant streams to provide a cooled and liquefied hydrocarbon stream and at least two at least partially vaporized refrigerant streams;

At least one first refrigerant compressor for compressing at least one of at least some evaporated refrigerant streams;

At least one second refrigerant compressor for compressing at least one of the at least some evaporated refrigerant streams;

(I) power for driving at least one of the second refrigerant compressors, and (ii) at least one gas turbine for providing a hot gas;

At least one steam heat exchanger for providing steam power from the hot gas;

At least one steam turbine driven by steam power to drive at least one of the first refrigerant compressors;

One or more storage tanks for liquefied hydrocarbons and / or refrigerant components,

The at least one gas turbine is located within a turbine-assembly region located away from the first and second refrigerant compressors and from the at least one storage tank.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following, embodiments of the present invention will be described by way of example only and with reference to the accompanying non-limitative drawings.

1 is a first configuration diagram of a hydrocarbon cooling process according to an embodiment of the present invention.
2 is an enhanced schematic diagram of a hydrocarbon cooling process.
Figure 3 is a more detailed schematic diagram illustrating various embodiments of the present invention provided with Figures 1 and 2;
Fig. 4 is a schematic floating bar showing another embodiment of the present invention. Fig.

For purposes of this description, a single reference numeral will be assigned to the line as well as the stream carried in the line. Like reference numerals refer to like parts.

1 is a general schematic diagram (1) for a hydrocarbon cooling process, generally involving cooling a hydrocarbon stream such as natural gas.

The method and apparatus disclosed herein include a method and / or apparatus for driving two or more refrigerant compressors in a hydrocarbon cooling process. In particular, the method comprises, at least,

- driving at least one gas turbine to provide (i) power and (ii) hot gas;

Passing the hot gas through at least one steam heat exchanger to provide steam power;

- using said power to drive at least one of the refrigerant compressors; And

- driving at least one other refrigerant compressor of the refrigerant compressor using said steam power to drive one or more steam turbines.

These steps may be performed as part of a method of cooling and liquefying the hydrocarbon stream in an on-shore plant or in a floating floating vessel or platform. However, when carried out in a floating vessel or on a floating platform comprising one or more storage tanks and / or refrigerant components for liquefied hydrocarbons, according to the present method, advantageously, on or in a floating vessel or on a floating platform, 1 and the second refrigerant compressor and at least one gas turbine in a turbine-assembly region located remotely from the at least one storage tank.

This makes the process significantly safer because the gas turbine can be located just outside the hydrocarbon inventory present in the compressor and storage tanks, such as LNG and refrigerant.

An optional advantage of the present invention is that the space required for the process can be saved.

Moreover, the embodiments disclosed herein are an improved method and apparatus for cooling a hydrocarbon stream, such as natural gas, which shows a method and apparatus with great flexibility in power requirements.

US 6,691, 531 B1 discloses a natural gas liquefaction system using two first and second gas turbines (reference numerals 700 and 702 in FIG. 1 of that document) for powering first and second propane and ethylene compressors Lt; / RTI > The hot exhaust gases from the gas turbine are directed to indirect heat exchanger 802 and the water / steam stream flowing in conduit 804 is directed to first and second steam turbines 704 and 706, which power the methane compressor. do. This system still has two gas turbines in close proximity to a large number of propane and ethylene compressors, despite the use of hot exhaust gases from the gas turbine, and has inherent safety risks that the present invention seeks to avoid.

Gas turbines are well known in the art and include aeroderivative-type turbines. Such gas turbines generally include an air compression system and are supplied with one or more of light hydrocarbon gases, typically methane, ethane, propane, etc., as fuel.

Steam heat exchangers for providing steam power from hot gases produced by gas turbines are also well known in the art. The steam heat exchanger is capable of recovering thermal energy of the hot gas and includes any kind or type of steam creator such as a waste heat recovery unit.

The two or more refrigerant streams of step (a) of the process of the present invention may be in separate refrigerant circuits or may be individual fractions or portions of a single refrigerant circuit as described in WO 96/33379 Al.

The first and second refrigerant compressors may be in separate refrigerant circuits or in the same refrigerant circuit, such as the single refrigerant circuit mentioned above. If the first and second refrigerant compressors are in the same circuit, at least some of the at least some evaporated streams may pass through at least one of the same refrigerant compressors.

The present invention can include two or more cooling processes, wherein each process has one or more steps, portions, and the like. For example, each cooling process may include one to five heat exchangers, such as two or three heat exchangers. Each heat exchanger may have an associated refrigerant compressor. Optionally, each cooling process optionally includes at least one refrigerant stream and at least one refrigerant compressor as part of the same or separate refrigerant circuits.

In one embodiment of the present invention, the hydrocarbon cooling process comprises two or three cooling processes. The first cooling step is preferably to lower the temperature of the hydrocarbon feed stream below 0 ° C, typically -20 ° C to -70 ° C. Such a first cooling process is sometimes referred to as a " pre-cooling " process.

The second cooling process is preferably separated from the first cooling process. That is, while the refrigerant in the second refrigerant stream may pass through all the heat exchangers in the one or more heat exchangers in the first cooling process, preferably in the first cooling process, the second cooling process is performed in the second And one or more heat exchangers using a refrigerant. Such a second cooling process is sometimes referred to as a 'main cooling' process.

Preferably, at least one of the refrigerant compressors of the second process is a cryogenic refrigerant compressor, and the compressor is more preferably driven by the power provided by the gas turbine (s).

Preferably, at least one of the refrigerant compressors of the first process is a pre-cooled refrigerant compressor, which is connected to the steam turbine (s) (which is powered by the steam power provided by the hot gas from the gas turbine (s) It is more preferable to drive it. If there are two or more first refrigerant compressors, it is preferred that all of the first refrigerant compressors are pre-cooled refrigerant compressors. Preferably, all the refrigerant compressors of the first process are pre-cooled refrigerant compressors.

Thus, in order to provide a cooled and liquefied hydrocarbon stream and at least a portion of at least a portion of the evaporated refrigerant stream, the passage of the hydrocarbon feed stream to the two or more refrigerant streams in step (a) 1 cooling process, wherein the hydrocarbon feed stream is pre-cooled to at least one first refrigerant stream to produce a cooled hydrocarbon stream and a vapor stream by the steam turbine (s) At least a portion of the evaporated first refrigerant stream being compressed using the first refrigerant compressor (s) being driven, wherein the temperature of the cooled hydrocarbon stream is lowered relative to the at least one second refrigerant stream The liquefied hydrocarbon stream, and at least one at least partially evaporated second refrigerant compressed by the second refrigerant compressor driven by power It provides every stream.

This application of an electric drive compressor for a second cooling process and a vapor-driven compressor for a first cooling process, even when applied to offshore floating vessels or platforms, as well as to coastal plants, Since the steam needs to be started before the process and the auxiliary steam generating means (e.g., multiple boilers) is used to provide steam more easily before the gas turbine is fully started to generate power, the second compressor is driven by steam Facilitates a more efficient and effective start of the process as compared to a process in which the first compressor is driven by power.

In one embodiment of the invention, there is a drive force to one or more refrigerant compressors, particularly when there is at least one shrink or shutdown of the gas turbine or steam turbine for exceptional or high demand or maintenance or other purposes In order to provide steam power or power, or one or more other providers of both, may be provided. With such additional feeds, the hydrocarbon cooling process can be operated continuously for as long as possible.

The present invention may be used as a stand-alone process or as part of a larger process or plant such as one or more pretreatment processes, post-liquefaction processes, and / or storage of a liquefied hydrocarbon stream requiring one or more storage tanks, It is particularly suitable when there is a limitation in the space available for the hydrocarbon cooling process.

Thus, the present invention is particularly suitable for being located in a floating vessel, a coast platform or a caisson. The floating vessel may generally be any movable or permanently anchored vessel with at least a hull, and is typically in the form of a ship, such as a tanker.

Such a floating vessel may have any dimensions, but is typically aspile. The dimensions of the floating vessel are not limited at sea, but their dimensions may be limited by the building and maintenance facilities of the floating vessel. Thus, in one embodiment of the present invention, the floating vessel or platform is less than 600 m in length, preferably less than 550 m in length, for example less than 500 m, so that it can be accommodated in conventional boat- m, typically 85 m.

The offshore platform may also be mobile, but generally can be positioned more permanently than the floating vessel. The offshore platform may also be floating and may also have any suitable dimensions.

In another embodiment of the present invention, the cooling method and / or the hydrocarbon cooling process is either a liquefaction process or a liquefaction process that provides a liquefied hydrocarbon stream such as liquefied natural gas. Preferably, the liquefied hydrocarbon stream is stored in one or more storage tanks, which may be located on or in any of the floating vessels or platforms.

Preferably, the or each gas turbine is located at least 50 m, preferably at least 100 m from the first and second refrigerant compressors. By placing the gas turbine (s) used in the present invention at least 50 m, preferably at least 100 m, from the refrigerant compressor, any undesirable action or situation relating to the gas turbine (s) Equipment, or apparatus having generally hydrocarbon content, such as an accumulator, a vessel, a store, and the like.

In particular, it is desirable to maintain a distance between the gas turbine (s) and the refrigerant compressor when it is necessary to be located closer together than in the typical case where no space limitations exist, such as in a floating vessel or on an offshore platform. A safety driver for the layout of a floating LNG plant is being discussed in a paper of the same name submitted to the 2003 AIChE Spring National Meeting: LNG & Gas Transportation Sessions.

The present invention preferably provides a nominal capacity (or nameplate) of liquefied hydrocarbon streams of 1 to 10 million tonnes per annum (MTPA) per year. The term "rated capacity" is defined as the number of days of plant operation per year multiplied by the daily production capacity of the plant. For example, some LNG plants operate for an average of 345 days a year. Preferably, the nominal ability of the hydrocarbon cooling process of the present invention is 3.5 to 7 MTPA.

The hydrocarbon feed stream can be any suitable gas stream that is cooled, preferably liquefied, but is typically a natural gas stream obtained from a natural gas or petroleum reservoir. Alternatively, the natural gas stream may be obtained from other sources including synthetic sources such as the Fischer-Tropsch process.

Typically, the natural gas stream consists essentially of methane. Preferably, the hydrocarbon feed stream comprises at least 50 mole percent methane, more preferably at least 80 mole percent methane.

Depending on the source, the natural gas may contain varying amounts of hydrocarbons heavier than methane, such as ethane, propane, butane and pentane, as well as some aromatic hydrocarbons. The composition varies depending on the type and position of the gas. In general, hydrocarbons heavier than methane need to be removed from natural gas for a variety of reasons, such as having difficult freezing or liquefying temperatures that can clog components of a methane liquefaction plant. C _2-4 hydrocarbons can be used as sources of natural gas liquids.

In addition, the natural gas stream may include non-hydrocarbons such as H ₂ O, N ₂ , CO ₂ , Hg, H ₂ S and other sulfur compounds.

If desired, the hydrocarbon feed stream comprising natural gas may be pretreated prior to use, either as part of a hydrocarbon cooling process or separately. This pretreatment may include other steps such as reduction and / or elimination of non-hydrocarbons such as CO ₂ and H ₂ S, or premature cooling, pre-pressurizing. Since these steps are well known to those skilled in the art, their mechanism is not discussed further herein.

Thus, the term "feed stream" includes compositions prior to any treatment, including washing, dehydration and / or scrubbing, as well as one or more compounds or substances including sulfur, sulfur compounds, carbon dioxide, water and C ₂₊ hydrocarbons But is not limited to) the composition of the present invention. The term " partially < / RTI >

Preferably, the hydrocarbon feed stream used in the present invention undergoes at least the minimum pretreatment required to substantially liquefy the hydrocarbon stream. Such a demand for liquefying natural gas is known in the art.

Any pretreatment may be performed near, next to, or farther away from the method of the present invention. Farther away therefrom includes coastal / maritime separation or two different marine locations.

Each refrigerant stream utilized in the present invention may be formed from a single component such as propane or nitrogen or from a mixture of two or more components selected from the group including nitrogen, methane, ethane, ethylene, propane, propylene, butane, And may be a mixed refrigerant to be formed.

Other processes, zones, or steps of any portion of the hydrocarbon cooling process may include the same or different types of refrigerant in a manner known to those skilled in the art, and therefore the present invention is not thereby limited.

In one embodiment of the present invention, at least one of the first refrigerant and the second refrigerant is a mixed refrigerant. It is preferred that both the first and second refrigerants are optionally mixed refrigerants comprising different mixture ratios and / or compositions.

The term "refrigerant compressor" includes any unit, device or mechanism that can increase the pressure of the refrigerant stream. This includes a refrigerant compressor with a single compression process or step, or a refrigerant compressor with multi-stage compression or stages, more specifically a multi-stage refrigerant compressor in a single casing or shell. The evaporated refrigerant stream to be compressed can be provided to the refrigerant compressor at different pressures. Some processes or steps of the hydrocarbon cooling process may include two or more refrigerant compressors in parallel, in series, or both. The present invention is not particularly limited by the type or arrangement or layout of refrigerant compressors or refrigerant compressors in any refrigerant circuit.

It may also be desirable to include a hydrocarbon feed stream prior to any pretreatment or any major cooling step or both. Compressors other than refrigerant compressors are commonly used as part of one or more of the above-described pretreatment processes or steps.

Thus, the present invention extends to the use of power or steam power or power and steam power derived from one or more gas turbines, especially when such other compressors are part of a hydrocarbon cooling process, to drive one or more other compressors. The hydrocarbon cooling process may extend to any treatment of the gas stream that is cooled prior to passing the hydrocarbon stream through at least one of the refrigerant streams. This includes reduction and / or elimination of non-hydrocarbons as described above, especially including an acid gas removal unit. But also includes reduction and / or elimination of hydrocarbons heavier than methane prior to any major cooling step or step.

And, one or more compressors other than the refrigerant compressor can be used to compress boil-off gas from, for example, a storage tank, to compress any end flash gas from an end-flash vessel, Or for any other post-cooling compression or recompression of the same gas, at one or more stages using a cooled hydrocarbon stream.

Thus, one or more of such other compressors may include any gas or combination of gases that is not limited to a methane-rich gas. Such gases include nitrogen, carbon dioxide, and the like.

In one embodiment of the invention, the steam power is used for more than one, preferably more than 50%, and optionally all of such other compressors. In a cooling and / or liquefaction process or plant, such other compressors generally have a variety of compressor sizes, thus having various power-requirements, and the steam power has the advantage that it is effective regardless of the size or power-requirements of the compressor.

1, a hydrocarbon feed stream 10 passes through a first cooling process 12 using a first refrigerant stream 35 circulated in a first refrigerant circuit 35 to produce a cooled hydrocarbon It can be seen that stream 20 is obtained.

1, the first refrigerant stream 35 is preferably a mixture of any suitable components or components including two or more such as nitrogen, methane, ethane, ethylene, propane, propylene, butane, .

The first cooling process 12 may include one or more parallel, series, or both heat exchangers through which the hydrocarbon feed stream 10 passes.

Preferably, the first cooling step 12 is carried out in such a way that the feed stream 10 is preferably cooled to a temperature below 0 ° C, for example from -20 ° C to -70 ° C, Is cooled to -20 ° C to -45 ° C or -40 ° C to -70 ° C.

The first refrigerant stream 35a, which has been at least partially (normally completely) evaporated, is supplied from the first cooling process 12 to the first refrigerant compressor 34, at least one first ambient cooler cooler 42a, such as a water and / or air cooler, and at least one first expansion valve 44a.

The cooled hydrocarbon stream 20 from the first cooling process 12 is then passed through a second refrigerant stream 37 circulating in the second refrigerant circuit 37 and preferably a second refrigerant stream 37 using a mixed refrigerant, And is sent to step (14).

There may be various arrangements for the cooled hydrocarbon stream 20 and the second refrigerant circuit 37 in the second cooling process 14. Such arrangements are known in the art. Such an arrangement may optionally include one or more steps in one vessel, such as the main cryogenic heat exchanger, and optionally at another pressure level.

The second cooling process 14 may lower the temperature of the cooled hydrocarbon stream 20 to provide a liquefied hydrocarbon stream 30, such as LNG, at a temperature of about -130 ° C or less.

In the simplified form shown in Figure 1, in the second refrigerant circuit 37, the evaporated second refrigerant outlet stream 37a, in preparation for reuse, comprises at least one second refrigerant compressor 36, 2 ambient cooler 42b, such as a water and / or air cooler, and at least one second expansion valve 44b. Alternatively, the second refrigerant refrigerant stream 37 is at least partially cooled by passing through a first cooling process 12 as shown in FIG.

FIG. 1 shows a method of driving the first and second refrigerant compressors 34, 36.

In Figure 1, there is at least one gas turbine 54 positioned separately from the hydrocarbon cooling process. One or more gas turbines 54 provide power through the first generator 56 in a manner known in the art. Moreover, hot gases from one or more gas turbines 54 pass through one or more steam heat exchangers 58 via fuel line 57 to recover heat therefrom in a manner known in the art. Water is provided to the steam heat exchanger 58 via the water line 59 to provide a low temperature flue gas 61 and a vapor stream 72 which is supplied in one or more vapors And has steam power for driving the turbine.

1, the electric power from the first generator 56 is transmitted through the power line 74 to power the first electric motor 76 driving the second refrigerant compressor 36 .

The steam power of the steam line 72 is transferred to the first steam turbine 82 and used to drive the first refrigerant compressor 34 directly. To this end, the steam turbine 82 is coupled to the refrigerant compressor 34 mechanically, e.g. via a shaft 85.

One advantage of the present invention is that by driving the first refrigerant compressor (s) using power and the second refrigerant compressor (s) by a steam turbine utilizing steam power from the hot gas from the gas turbine (s) Flexibility in the delivery of power requirements for refrigerant compressors is increased.

Another advantage of the present invention is that by avoiding relying on the use of all power powered equipment, space is saved to some extent so that a process or plant using the present invention can be deployed or designed more space- .

Another advantage of the present invention is that it increases safety and reduces risk factors in a process or plant using the present invention in a limited space or place, e.g., at sea.

The steam turbine 82 may be of any suitable type. For example, it may be a back pressure steam turbine that generally produces a low pressure steam stream that may be utilized in a plant or around the plant to meet a heat requirement in or around the process.

However, alternatively, a condensing steam turbine may be employed. For example, by employing hot oil instead of low pressure steam, at least some of the thermal requirements of the plant can be met. One advantage of using a condensing steam turbine is that the specific power generation in the condensing steam turbine is relatively high. Generally it can be double the backpressure steam turbine. Thus, less steam is required to provide the same output of mechanical and / or electrical power. This is particularly advantageous when there is a lack of fresh water, such as in offshore and / or floating process plants where steam is generated from seawater treated, for example, by desalination plants. Thus, by means of a condensing steam turbine, smaller desalination plants are allowed, thereby saving space and capital expenditure.

Also, by reusing at least a portion of the water and / or water generated from the steam discharged from the steam turbine 82 after driving the steam turbine 82, the need for water to produce steam can be reduced.

Figure 2 shows an enhanced schematic (2) for a hydrocarbon cooling process that generally involves cooling a hydrocarbon stream such as natural gas.

As part of the hydrocarbon cooling process and prior to any major cooling of the stream being treated, the initial hydrocarbon stream comprising natural gas is pretreated to include at least some of the heavy hydrocarbons and non-acidic gases (including but not limited to acidic gases) Hydrocarbon impurities such as carbon dioxide, water, mercury, sulfur and sulfur compounds can be separated.

For example, Figure 2 shows that the initial hydrocarbon stream 5 fed by the pipeline from a well or well-head in a manner known in the art is first subjected to entrainment in the unit 6, Through a feed compressor 13 and then through a reduction and / or elimination of impurities through an acidic gas removal unit (AGRU) 11 to provide a stream 90 of reduced impurities. Other streams, such as CO ₂ , from AGRU 11 may be conveyed along line 115 and compressed by second compressor 32 to provide, for example, a compressed CO ₂ stream 120.

The stream of reduced impurities 90 is then subjected to NGL-extraction through one or more separators, typically one or more NGL sorters 26, to provide a methane-rich feed stream 100. In addition, the methane-enriched stream 100 may be compressed through another compressor 28 if it is desirable or necessary to subsequently increase the pressure of the hydrocarbon feed stream 10 for the cooling process. Any residual methane recovered from the NGL stream (s) may be conveyed along line 110 and directed to another second compressor 33 for reintroduction into the main cooling process as part of the feed stream 10 Lt; / RTI >

The hydrocarbon feed stream 10 so formed is passed through a first cooling cycle 12 using the first refrigerant stream 35 circulated in the first refrigerant circuit 35 as described above. Fig. 2 shows an example of the use of two first refrigerant compressors 34a and 34b in the first refrigerant circuit 35. Fig. In order to simplify Fig. 2, other components of the first refrigerant circuit 35 are not shown.

In one embodiment of the present invention, each heat exchanger of the first cooling process 12 comprises a different first refrigerant pressure. The expanded refrigerant from each pressure process may be compressed in one or more first refrigerant compressors, e.g., using different refrigerant compressors for different refrigerant inlet pressures.

The cooled hydrocarbon stream 20 from the first cooling process 12 is then supplied to the second refrigerant stream 37 circulated in the second refrigerant circuit 37 as described above and preferably to the second refrigerant stream 37, And is sent to the second cooling process 14 in use. In the second refrigerant circuit 37 the evaporated second refrigerant outlet stream 37a passes, for example, through two second refrigerant compressors 36a and 36b and the second refrigerant stream 37 passes through a first cooling step 12 At least partially.

Optionally in conjunction with other parts of the process and / or apparatus for liquefying the hydrocarbon stream as described above, to provide a hydrocarbon feed stream, a cooled and / or liquefied hydrocarbon stream and / or a liquefied hydrocarbon stream in addition to cooling by the first and second cooling processes, Or additional cooling of the refrigerant stream may be provided by one or more other refrigerants, or a refrigerant cycle.

And, for example, the liquefied stream 30 may provide a selectively subcooled stream 40 via a third cooling process 16 (shown in dashed lines), preferably sub-cooling. Subcooling may be provided by passing the liquefied stream 30 through one or more stages using one or more supercooled heat exchangers. Cooling by the third refrigerant compressed by another refrigerant compressor (38) is preferably supplied to the above or each heat exchanger of subcooling.

In addition, those skilled in the art will readily understand that after liquefaction, liquefied natural gas can be further processed if desired. As an example, the obtained LNG can be depressurized by a Joule-Thomson valve or by a cryogenic turboexpander.

For example, the configuration diagram (2) of FIG. 2 shows that a selectively subcooled stream 40 is delivered into a final gas / liquid separator, such as an end flash vessel 18, to provide a methane-rich liquid bottom stream 50 (Which may be delivered to the gas stream 22) and an overhead gas stream 60 are provided. In addition, any boil-off gas 70 from the storage tank 22 may be added to the end flash vessel 18. The overhead gas stream 60 may be compressed by another compressor 24 in a manner known in the art to produce a stream 80 for use as a fuel stream, a product stream, and the like.

2 is a schematic block diagram of a refrigerant compressor according to the first embodiment of the present invention in which not only the first refrigerant compressors 34a and 34b and the second refrigerant compressors 36a and 36b but also other refrigerant compressors such as a subcool refrigerant compressor 38, Non-refrigerant compressors, such as the compressors 13, 24, 28, 32, 33 discussed above.

The present invention extends to include any other compressor involving, associated with, or associated with any related process including a method of cooling a hydrocarbon stream, a hydrocarbon cooling process, or a pretreatment and post-liquefaction process (not discussed herein) do.

Fig. 3 shows details of a method for driving the refrigerant compressors 34 and 36 of the configuration diagrams (1 and 2) shown in Figs. 1 and 2, as well as another embodiment of the present invention.

In Figure 3, there is at least one gas turbine 54 located within the turbine-assembly region 52, and the turbine-assembly region is preferably separated from the hydrocarbon cooling process as shown in Figures 1 and 2 have. In turbine assembly region 52, one or more gas turbines 54 may be provided with air from an air inlet 53. The air is first compressed and mixed with a fuel, such as methane or other light hydrocarbon gases, and then ignited.

One or more gas turbines 54 provide power through the first generator 56 in a manner known in the art. Moreover, the hot gases from the one or more gas turbines 54 can flow through the flue line 57 (which may optionally be enriched with additional fuel gas by the fuel line 57a) To the steam heat exchanger (58). Water, typically high pressure water, is provided through the water line 59 into the steam heat exchanger 58 to provide a low temperature flue gas 61 and a typically high pressure steam stream 72, Has steam power to drive one or more steam turbines in a manner known in the art.

In the arrangement shown in Figure 3, the power from the generator 56 is supplied to the at least one electric motor via the power line 74 to drive at least one refrigerant compressor. For example, Figure 3 shows a line 74 extending to a first electric motor 76 driving a second refrigerant compressor 36, such as one or both of the second refrigerant compressors 36a, 36b shown in Figure 2 . The power at line 74 may be used to power one or more other electric motors, for example pumps, fans and other electrical services, in a remote or self-sufficient location or environment, such as a floating vessel or an offshore platform, Lt; RTI ID = 0.0 > 78 < / RTI >

The steam power of the steam line 72 is transferred to at least the first steam turbine 82 used to drive at least the first refrigerant compressor 34 such as the two first refrigerant compressors 34a and 34b shown in Figure 2 do. A portion of the steam power of the steam line 72 is supplied to the second steam turbine 84 to drive one or more other compressors such as one or more compressors 13, 24, 28, 32, 33, To at least one other steam turbine as shown in FIG. A portion of the steam power of the steam line 72 may also be used to drive the second generator 88 to provide power that can be supplied to the power line 74 by way of line 89, 3 < / RTI > steam turbine (86).

The second generator 88 is an example of another supply of power in the present invention.

3 also shows a separate boiler 62 that can provide steam for additional steam power combined with the steam power of line 72 using fuel gas from fuel line 64 .

Thus, the present invention provides the use of steam power or power or one or more other feeders of both to aid one or more gas turbines 54. [

In addition, the use of additional steam power from one or more individual boilers, such as the boiler 62 of FIG. 3, can also be used to reduce the amount of steam in the hydrocarbon cooling process < RTI ID = 0.0 > .

The present invention provides flexibility in the use of both the power and steam power in the hydrocarbon cooling process and optionally in other comprehensive or separate parts of the treatment of the initial hydrocarbon stream and / or the liquefied product stream. In this way, the size, design and inter-use of the various gas turbines, steam turbines and generators can be utilized in the most effective manner to provide the requirements of the hydrocarbon cooling process and the additional process, step or process . The present invention is not limited by which source of power drives which refrigerant compressor or compressors.

Other compressors, such as those shown in FIG. 2, can be easily powered by balancing the power requirements of one or more gas turbines 54 with the requirements of a larger refrigerant compressor. Typically, it is desirable to utilize as much or as much of the steam power provided from the heat therefrom in order to make the most of energy from one or more gas turbines 54 (otherwise the energy is discarded).

In this way, the invention is particularly suitable when such flexibility is required in a space-constrained plant or process, such as in a floating vessel or coastal platform. For example, the floating LNG vessel has a limited space for the hydrocarbon cooling process and has a much more limited space if additional processing such as impurities and / or heavy hydrocarbon generation and removal processes is present. It is known in the art that a very careful design is required in a limited space situation and the present invention is directed to providing a remote control of at least one gas turbine 54 with increased flexibility in the use of power available from at least one gas turbine, Provides increased safety by location.

Figure 4 shows an example of a floating vessel 7 in which there is a liquefaction plant 2a including at least a first cooling process 12 and a second cooling process 14 as described above. One or more gas turbines are located in the turbine-assembly region 52 away from the liquefaction process, preferably at least 50 m or preferably at least 100 m apart. The hydrocarbon feed stream 10 is cooled by the first and second cooling stages 12 and 14 to provide a liquefied hydrocarbon stream 50 that is delivered into the storage tank 22 . Another tank 23 for storing other components such as propane is provided in the floating vessel 7 for storage of the components required in the storage or liquefaction process of the product stream, such as LPG, such as components for the refrigerant of the refrigerant process . It is also desirable to have a distance between the turbine-assembly region 52 and such one or more storage tanks 22, 23.

The arrangement shown in Fig. 4 shows another advantage of the present invention. The present invention relates to a power generation (generally one or more gas turbines) for a hydrocarbon cooling process in which the main use of power, typically a refrigerant compressor, is located near or beside the generally required use, By separating as far as possible from units or hydrocarbons, such as propane, which are known to have a greater risk factor than other units or hydrocarbons, preferably within design constraints, thereby increasing safety and reducing risk factors. This is especially the case when space constraints or restrictions exist, such as in an offshore platform or floating vessel.

US 7,114,351 B2 describes a system for liquefying natural gas using all powered equipment. According to this document, the system and method are effective for generating sufficient power for operation of the liquefaction process.

However, the use of electric power for all operations of the liquefaction process requires a very large number of associated transformers, switchgear and other electrical units and devices, all of which require a very large space. Thus, the systems and methods of US 7,114,351 are not suitable for space-constrained processes and operations. Moreover, the system of US 7,114,351 is limited to the use of only powered equipment and there is no flexibility in the use of other powered equipment.

Table 1 shows relative comparison data for three different systems for powering the hydrocarbon cooling process as shown in FIG. The data in Table 1 is based on driving the refrigerant compressors of the same number, type and arrangement to cool the same Heating Value for the hydrocarbon feed gas and for the production of the same amount of LNG by each system. The value is a relative value with the hybrid system set to "100%".

The "electricity" system is based on the use of all equipment that is powered to cool the feed gas, as described in US 7,114,351 B2. The "all steam" system is based on the use of all steam powered equipment. "Hybrid" systems are based on the present invention employing both power and steam power to drive other refrigerant compressors.

Electrical equipment space% Fuel gas% carbon dioxide % hybrid 100 100 100 Electricity 130 91 91 All steam 60 133 133

The first column of Table 1 provides a relative comparison of the space required to locate all the electrical equipment needed for the three systems. As expected, while the electrical system requires the most space, all steam systems require the least space because no generator, transformer, etc. are required.

The second column provides a relative comparison of the amount of fuel gas required to drive the gas turbine (s) to run the three systems. It can be seen that the fuel gas required for the electrical system is the least, while the fuel gas required to provide the same amount of LNG using all the steam systems is one-third greater than for the hybrid system of the present invention.

In the third column of Table 1, when the same amount of LNG is produced, the amount of carbon dioxide produced by each system can be determined. Thus, electrical systems produce the least amount of carbon dioxide while all steam systems produce the greatest amount of carbon dioxide.

The data in Table 2 show that the present invention provides an adequate balance between space requirements, fuel gas requirements and generated carbon dioxide requirements. These factors can be used to account for the balance between the CAPEX and / or OPEX for the hydrocarbon cooling process, particularly the natural gas liquefaction plant, and the efficiency of such a process and / or plant, especially in a limited space.

Those skilled in the art will appreciate that the invention can be practiced in many different ways without departing from the scope of the appended claims.

Claims (18)

A method for cooling and liquefying a hydrocarbon stream in a floating vessel or on a floating platform,
(a) passing a hydrocarbon feed stream over two or more refrigerant streams to provide a cooled and liquefied hydrocarbon stream and at least a portion of two or more evaporated refrigerant streams;
(b) compressing at least one of at least a portion of the evaporated refrigerant stream through the at least one first refrigerant compressor;
(c) compressing at least one of the at least some evaporated refrigerant streams through the at least one second refrigerant compressor;
(d) driving at least one gas turbine to provide (i) power and (ii) hot gas;
(e) passing the hot gas (ii) of step (d) through one or more steam heat exchangers to provide steam power;
(f) using the power to drive at least one of the second refrigerant compressors; And
(g) driving at least one of the first refrigerant compressors using the steam power to drive one or more steam turbines,
The method is carried out in a floating vessel or a marine platform comprising one or more storage tanks for liquefied hydrocarbons and / or refrigerant components, wherein the one or more gas turbines are installed in or on the floating vessel or on the offshore platform, A method for cooling and liquefying a hydrocarbon stream in a turbine-assembly region located at least 50 m away from a refrigerant compressor and from one or more storage tanks. The method of claim 1, wherein at least one of the second refrigerant compressors is a cryogenic refrigerant compressor. The method of claim 1, wherein at least one of the first refrigerant compressors is a pre-cooled refrigerant compressor. The method of claim 1, wherein the method further comprises one or more other treatment steps of either the hydrocarbon feed stream prior to step (a), or the cooled hydrocarbon stream of step (a), or both streams, Wherein at least one other compressor is included, wherein either power or steam power or both power and steam power drives at least one of the other compressors. 5. The method of claim 4, wherein at least one of the other compressors is to compress at least one stream other than at least a portion of the evaporated refrigerant stream of step (b) and step (c). 6. The method of any one of claims 1 to 5, further comprising one or more other feeders of steam power or power. delete 6. The process according to any one of claims 1 to 5, wherein the liquefied hydrocarbon stream has a nominal capacity of 1-10 MTPA. 6. The method of any one of claims 1 to 5, wherein the cooling stream comprises at least a first cooling process and a second cooling process, wherein the refrigerant stream for the first and second cooling processes is a mixed refrigerant, Liquefaction method. 6. The method of any one of claims 1 to 5, wherein at least one of the at least one steam turbine is a condensing steam turbine. 6. A method according to any one of claims 1 to 5, wherein the floating vessel or marine platform has a length of less than 600 m and a width of 100 m. 6. The method according to any one of claims 1 to 5, wherein the step (a) comprises a first cooling step and a second cooling step separate from the first cooling step, wherein in the first cooling step, the hydrocarbon The feed stream is pre-cooled to at least one first refrigerant stream to provide a cooled hydrocarbon stream and at least one at least partially vaporized first refrigerant stream compressed in step (b), wherein in the second cooling step, Wherein the temperature of the stream of hydrocarbons is lowered relative to the at least one second refrigerant stream to provide a liquefied hydrocarbon stream and at least one at least partially vaporized second refrigerant stream to be compressed in step (c) . 6. A process according to any one of claims 1 to 5, wherein the hydrocarbon stream comprises or essentially consists of natural gas. A floating vessel or offshore platform comprising an apparatus for cooling and liquefying a hydrocarbon stream on or in a floating vessel,
At least two cooling processes for passing a hydrocarbon feed stream over two or more refrigerant streams to provide a cooled and liquefied hydrocarbon stream and at least two at least partially vaporized refrigerant streams;
At least one first refrigerant compressor for compressing at least one of at least some evaporated refrigerant streams;
At least one second refrigerant compressor for compressing at least one of the at least some evaporated refrigerant streams;
(I) power for driving at least one of the second refrigerant compressors, and (ii) at least one gas turbine for providing a hot gas;
At least one steam heat exchanger for providing steam power from the hot gas;
At least one steam turbine driven by steam power to drive at least one of the first refrigerant compressors;
One or more storage tanks for liquefied hydrocarbons and / or refrigerant components,
Wherein the at least one gas turbine is located within a turbine-assembly region located at least 50 m away from the first and second refrigerant compressors and from one or more storage tanks.
delete 6. A gas turbine according to any one of the preceding claims, wherein the at least one gas turbine is located at least 100 m away from the first and second refrigerant compressors on and / or within the floating vessel or on the offshore platform, ≪ / RTI > in a turbine-assembly region. 6. The process according to any one of claims 1 to 5, wherein the liquefied hydrocarbon stream has a nominal capacity of 3.5 to 7 MTPA. 15. The floating vessel or marine platform of claim 14, wherein the at least one gas turbine is located within a turbine-assembly region located at least 100 m away from the first and second refrigerant compressors and from one or more storage tanks.

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