RU2754482C2 - Supplemented plant for production of liquefied natural gas and its operation method - Google Patents

Abstract

FIELD: gas industry.

SUBSTANCE: invention relates to plant (1) for the production of liquefied natural gas. Plant (1) contains two or more parallel processing and liquefaction lines (A, B), each of which contains cooling stage (14) designed to receive stream (13) of purified natural gas from gas processing stage (12), unit (16) of gas condensate liquid extraction for extracting liquids from natural gas (161), thereby generating stream (162) of light natural gas. Plant (1) for the production of liquefied natural gas contains additional liquefaction line (C) containing additional cooling stage (214) designed to receive additional flow of raw materials for generating additional liquefied natural gas. Additional flow of raw materials (210) contains two or more side flows taken from light natural gas taken from corresponding streams (163) of light natural gas from one or several parallel processing and liquefaction lines (A, B).

EFFECT: increased efficiency of liquefaction.

11 cl, 1 dwg

Description

Technology area

The present invention is directed to a liquefied natural gas (LNG) plant comprising a plurality of processing and liquefaction lines. The invention further relates to a method for retrofitting and / or operating such a plant for the production of liquefied natural gas.

State of the art

Natural gas can be liquefied for storage and transportation purposes because it takes up less volume in its liquid state than in its gaseous state. Typically, natural gas is treated prior to liquefaction to remove contaminants (such as H ₂ O, CO ₂ , H ₂ S, etc.) and heavy hydrocarbon molecules that can freeze during the liquefaction process.

Liquefaction of natural gas is an energy-intensive process. Therefore, the development and operation of plants for the production of liquefied natural gas in the most efficient way is an area of constant focus.

WO2006 / 120127 describes an LNG plant comprising a single liquefaction line for supplying LNG in liquid or "pseudo-liquid" form. LNG in liquid or "pseudo-liquid" form is sent to a separation unit to feed purified LNG and a nitrogen-rich stream.

WO201576975 describes a method for retrofitting a full-scale LNG plant in order to increase the productivity of an LNG plant and a method for operating such a retrofit plant. A small LNG plant with a capacity of less than 2 million tonnes per year can be integrated with the main LNG plant with a capacity of at least 4 million tonnes per year, so that the final flare gas and vapor produced from the main LNG plant, can be liquefied with a small natural gas liquefaction plant providing additional LNG. According to WO201576975, the performance of an integrated system can be improved by increasing the temperature of the gas stream leaving the main cryogenic heat exchanger of the main LNG plant and having a temperature of 5 ° C to 30 ° C over the design temperature.

WO2006009646 relates to hydrocarbon fluid processing plants, methods of designing hydrocarbon fluid processing plants, methods of operating hydrocarbon fluid processing plants, and methods of producing hydrocarbon fluids using hydrocarbon fluid processing plants. More specifically, some embodiments of the invention relate to plants for liquefying natural gas, methods of designing plants for liquefying natural gas, methods of operating plants for liquefying natural gas, and methods of producing LNG using plants for liquefying natural gas. One embodiment of the invention includes a hydrocarbon fluid processing unit comprising a plurality of types of process unit modules, the plurality of types of process unit modules comprising at least a first type of process unit module comprising one or more first process unit modules and a second type of process unit module, comprising two or more integrated modules of the second process unit, in which at least one of the modules of the first process unit and at least one of the modules of the second process unit have dimensions corresponding to their essentially maximum processing efficiency.

The essence of the invention

The aim of the invention is to provide a more efficient LNG plant.

In one aspect, the present invention is directed to a natural gas liquefaction plant for producing liquefied natural gas from a contaminated natural gas feed stream, a liquefied natural gas plant comprising two or more parallel gas processing and liquefaction lines located in process sections of a parallel contaminated feed stream. natural gas, each of which contains:

- inlet for receiving a portion of the feed stream of contaminated natural gas,

- a gas treatment stage to remove contaminants from the corresponding part of the contaminated natural gas feed stream, resulting in a purified natural gas stream,

- a cooling stage designed to receive a purified natural gas stream from a gas processing stage to cool at least a portion of a purified natural gas stream, the cooling stage comprising a gas condensate liquid recovery unit for extracting liquids from natural gas, thereby generating a light natural gas stream that at least partially further cooled in the cooling stage in order to at least partially liquefy, and

- outlet for the release of liquefied natural gas,

moreover, the installation for the production of liquefied natural gas contains at least one additional liquefaction line, and the additional liquefaction plant contains:

- inlet for receiving additional feed stream,

- an additional cooling stage designed to receive an additional feed stream for cooling an additional feed stream, resulting in the formation of additional liquefied natural gas, and

- outlet for withdrawing additional liquefied natural gas,

wherein the additional feed stream contains two or more side streams taken from respective light natural gas streams from two or more parallel processing and liquefaction lines.

A liquefied natural gas plant as defined above also contains liquefied natural gas plants containing more than one additional liquefaction line.

A natural gas liquids recovery unit for natural gas liquids recovery can operate with any suitable natural gas stream in the cooling step. According to an embodiment of the invention, the cooling stage comprises a first cooling unit for generating a pre-cooled purified natural gas stream and a second cooling unit configured to generate an additional cooled stream. An installation for the extraction of natural gas liquids for the extraction of liquids from natural gas can be performed on a pre-cooled purified natural gas stream.

The inlet of the additional liquefaction line is directly or indirectly fluidly coupled to pipelines in the respective treatment and liquefaction lines, which, in use, convey the respective streams of light natural gas. In addition, the inlet of the additional liquefaction line is directly or indirectly fluidly coupled to conduits in the respective treatment and liquefaction lines carrying any additional streams to be included by the additional feed stream.

The additional feed stream may contain additional streams, including one or more natural gas by-streams taken downstream of the inlet of the respective processing and liquefaction lines, such as a final flash gas stream, a flash gas stream (taken from one or more storage tanks LNG), purified natural gas stream. The gas treatment stage may comprise one or more gas treatment units (as explained in more detail below). The additional feed stream may further comprise one or more side streams taken from intermediate partially purified natural gas streams from respective gas treatment plants.

In addition, or alternatively, the additional feed stream may contain additional streams obtained from a fractionation unit for receiving and fractionating natural gas liquids obtained from a gas condensate liquids recovery unit. The additional stream may in particular be at least a portion of one or more methane-rich streams generated by respective fractionation units and / or at least a portion of one or more ethane-rich streams generated by respective fractionation units.

Depending on the composition of the additional feed stream, the additional liquefaction line may contain some gas treatment units and may include a gas condensate liquid recovery unit.

However, in accordance with an embodiment of the invention, at least 30 mol% of the additional feed stream is formed from the respective light natural gas streams generated by the NGL recovery units. In accordance with a preferred embodiment of the invention, at least 50 mol% or at least 75 mol% of the additional feed stream, for example 100 mol%, is generated from respective light natural gas streams generated by NGLs. The additional feed stream can only be generated from the corresponding light natural gas streams. The light natural gas stream generated by the NGL recovery unit is clean, lean and at a relatively high pressure, therefore does not require any additional gas processing units and does not require or requires relatively little compression. The more additional feed stream is generated by the corresponding light natural gas streams, the less compression and processing of gas is required relative to the additional liquefaction line.

The additional liquefaction line preferably does not contain an installation for the recovery of gas condensate liquids as an additional feed stream at least partially and preferably at least 30 mol.%, At least 50 mol.% Or at least 75 mol.% Already passed through the block for the extraction of gas condensate liquids. In accordance with an embodiment of the invention, the additional liquefaction line comprises only a relatively small unit for the recovery of gas condensate liquids. The additional liquefaction line requires a relatively small gas treatment stage with only a subset of gas treatment units from the treatment and liquefaction line, and preferably does not include a gas treatment stage since the additional feed stream has already been purified. Thus, an additional liquefaction line requires less hardware and is relatively cheap in both capital and operating costs.

By combining flows from two or more parallel processing and liquefaction lines, an additional liquefaction cycle can gain significant size to benefit from economies of scale.

Corresponding light natural gas streams from one or more parallel processing and liquefaction lines may be referred to as C _1- rich streams or C ₂ ⁺ -depleted streams. Corresponding light natural gas streams may, for example, be obtained from the vapor phase of a reflux vessel in a wash column, in which case the light natural gas streams may have temperatures ranging from minus 40 ° C to minus 50 ° C, for example, minus 45 ° C. and at pressures in the range 40-55 bar abs. Side streams taken from the light natural gas stream to be contained in the additional feed stream can be directed directly to the additional liquefaction line, i. E. without recompression.

Light natural gas streams can also be heat-integrated with a first or pre-cooling unit to recover at least a portion of the cold present in these streams before receiving a side stream. In such an embodiment of the invention, the side streams taken from LNG streams after cold recovery may have a temperature in the range of + 10 ° C to + 20 ° C, for example, + 15 ° C, at a pressure in the range of 40-55 bar abs. ...

Preferably, the respective light natural gas streams are integrated into the heat with a pre-cooling step, especially when a collection and compression unit is provided (the collection and compression unit will be explained in more detail below).

Side streams taken from the respective light natural gas streams have a relatively high pressure associated with the pressure of the contaminated natural gas feed stream and / or the purified natural gas stream (30-100 bar), which can be fed to the additional liquefaction line without recompression or only with moderate recompression. In some embodiments, the pressure of the additional feed stream is selected to be higher (e.g., 10 bar or 20 bar higher) than the pressure of the contaminated natural gas feed stream to facilitate efficient cooling and liquefaction, and higher pressures can be obtained at relatively low cost. considering the relatively high pressure of at least some of the streams making up the additional feed stream.

In another aspect, a method is provided for retrofitting an existing LNG plant to increase the potential for liquefied natural gas production, wherein the existing LNG plant comprises two or more parallel lines for processing and liquefying LNG from a polluted natural gas feed stream. gas, in which two or more parallel processing and liquefaction lines are arranged in parallel to treat portions of the contaminated natural gas feed stream, and each of them is configured to:

- receiving a portion of the stream of contaminated natural gas,

- removing pollutants from an appropriate portion of the contaminated natural gas feed stream, thereby creating a purified natural gas stream,

- cooling at least a portion of the purified natural gas stream and recovering natural gas liquids, thereby generating a light natural gas stream, which is at least partially further cooled in a cooling stage,

moreover, the conversion method includes:

- providing an additional liquefaction line, and the additional liquefaction line contains an additional cooling stage designed to receive and liquefy an additional feed stream to obtain additional liquefied natural gas,

- fluid communication of an additional liquefaction line with two or more light natural gas streams of two or more processing and liquefaction lines to obtain side streams of two or more light natural gas streams to be added by an additional feed stream, thereby creating an upgraded liquefaction plant natural gas.

The method may further include fluid connection of an additional liquefaction line to one or more additional streams (as described above), including side streams taken downstream of the inlet of the treatment and liquefaction line, such as from a final flash stream, a vaporized gas stream (taken from one or more LNG storage tanks, a purified natural gas stream, intermediate partially purified natural gas streams from respective gas treatment plants and by-streams obtained from a fractionation unit designed to receive and fractionate produced natural gas liquids from a NGL recovery unit (eg, side streams from one or more methane-rich streams and / or one or more ethane-rich streams).

The additional liquefaction line can be as described above. The additional liquefaction line may preferably not contain a NGL recovery unit, since the additional feed stream has already passed through the NGL recovery unit. The additional liquefaction line may also not contain a gas treatment stage, since the additional feed stream has already been purified.

The method may further include eliminating problems with an existing LNG plant, for example, by replacing or servicing parts of an existing LNG plant, particularly upstream of where liquids are extracted from natural gas. Removing bottlenecks means improving the design capacity of an existing LNG plant by increasing the design capacity of the most limiting part of the LNG plant.

The retrofit method is especially useful in situations where the power of the warm ends, i.e. the pretreatment unit (described in more detail below), the gas treatment stage, the NGL recovery unit, have been designed for a richer and more polluted gas than it actually is, resulting in to the appearance of a spare ullage at the warm ends of the treatment and liquefaction lines, while the cold end, that is, equipment downstream of the gas condensate liquids recovery unit, is already operating at its design capacity or close to it.

In addition, this method is especially useful when existing processing and liquefaction lines are limited by the available gas turbine output, limiting the available refrigeration capacity.

In accordance with a further aspect, there is provided a method of operating a (modified) plant for producing liquefied natural gas as described above, the method comprising

- operation of two or more parallel processing and liquefaction lines, while the operation of two or more parallel processing and liquefaction lines provides for the reception of the corresponding parts of the feed streams of contaminated natural gas by two or more parallel processing and liquefaction lines at the feed pressure, and

- operation of an additional liquefaction line, and the operation of the additional liquefaction line includes the supply of an additional feed stream containing two or more streams of light natural gas taken from two or more parallel processing and liquefaction lines (A, B), and the additional feed stream is provided at additional pressure supply pressure which is at least 10 bar higher than the supply pressure.

As above, the additional feed stream may contain one or more additional streams, including side streams removed downstream of the inlet of the treatment and liquefaction line, such as from a final flash stream, a vaporized gas stream (taken from one or more reservoirs for LNG storage), purified natural gas stream, intermediate partially purified natural gas streams between respective gas treatment plants and by-streams obtained from the fractionation unit intended for receiving and fractionation of natural gas liquids obtained from the NGL recovery unit (for example, one or more streams enriched in methane and / or one or more streams enriched in ethane).

Since for an additional liquefaction line that does not provide for NGL extraction, there are no pressure limitations to be taken into account associated with NGL extraction. Thus, the additional feed pressure can be selected higher than the feed pressure to facilitate efficient cooling and liquefaction. The additional feed pressure can even be 20 bar higher than the feed pressure. The additional feed pressure can be higher than 50 bar abs. or may even be higher than 60 bar abs. (bar abs. = absolute bar).

Brief description of graphic materials

The figures illustrate one or more implementations in accordance with the present invention by way of example only and not by way of limitation. In the figures, like reference numbers refer to the same or similar elements. In addition, a single item number will be used to denote a pipeline or line and the flow carried along that line.

FIG. 1 schematically illustrates an embodiment of the invention.

Detailed description of the essence of the invention

The following examples of certain aspects of certain embodiments of the invention are provided to facilitate a better understanding of the present invention. These examples are in no way to be construed as limiting or defining the scope of the invention.

A plant for the production of liquefied natural gas is provided, containing a plurality of liquefaction lines, of which at least one line, called an additional liquefaction line, liquefies the gas streams received from other lines (called processing and liquefaction lines). An additional liquefaction line is preferably added to the existing plant as a retrofit.

In existing plant designs, that is, plants that do not contain an additional liquefaction line as described herein, fuel is typically obtained from gas streams obtained from the processing and liquefaction lines, such as portions of the final flashing gas and the top of the purification column used to recover gas condensate. liquids that are relatively dry and clean.

A liquefied natural gas plant is currently envisaged, in which the fuel is mainly obtained from the natural gas feed stream upstream of the refrigeration and gas treatment units. The aforementioned relatively lean and clean gas streams are now fed to the additional liquefaction line as an additional feed stream.

It is recognized that the treatment required for fuel gas, i.e. for fuel gas supplied to gas turbines, boilers, furnaces of the LNG plant) is less stringent than the requirements for LNG. For example, for a fuel gas, CO ₂ removal is less stringent, heavy hydrocarbon removal is less stringent, H ₂ S removal is less stringent, water removal is less stringent, and mercury removal is less stringent. Processing requirements to make the contaminated natural gas feed stream usable for fuel may include some hydrate control (i.e. preheat, dew point), pressure control, and possibly superheat control, but overall less hardware is required. than gas processing according to LNG specifications.

Therefore, it is recognized that relatively clean and lean gas streams can be liquefied more efficiently to produce additional LNG than those used as a fuel stream.

An additional liquefaction line can advantageously be added to existing LNG plants containing two or more processing and liquefaction lines, particularly in situations where there is excess capacity available upstream in the NGL and upstream.

In accordance with document WO201576975, the temperature of the main cryogenic heat exchanger is raised to ensure sufficient production of the final flash gas and flash gas for feeding to the small LNG plant. This approach is disadvantageous as it depends on the additional power available in the main cryogenic heat exchanger. In addition, temperature changes can move operating parameters outside the original window of the main cryogenic heat exchanger design, resulting in less efficient operation. In accordance with current embodiments of the invention, it is not necessary to change the temperature of the main cryogenic heat exchanger.

Embodiments of the invention presented herein allow an LNG plant, including an additional liquefaction line, to be operated without the need for an increase in temperature.

Instead of raising the temperature of the main cryogenic heat exchanger, or more generally for the cold end of the line, various measures are proposed to provide a sufficiently large additional feed stream to benefit from economies of scale. One of these measures is to remove the fuel gas from a different location in the installation, i.e. from a position upstream of the second refrigeration unit (see detailed description below, also known as the main cryogenic heat exchanger), which allows the use of cleaner and leaner gas from the treatment lines. and liquefaction to an additional liquefaction line.

With reference to FIG. 1, an installation for the production of liquefied natural gas (1) is provided for the production of liquefied natural feed gas from a feed stream of contaminated natural gas (10). The contaminated natural gas feed stream 10 may come from a pretreatment unit 2 that is configured to receive one or more natural gas streams 30 from a source or well and discharge the contaminated natural gas feed stream 10 having a well-defined constant pressure, flow rate and composition. Therefore, the pretreatment unit 2 can be equipped with a sludge catcher, pressure control devices, stabilizers and metering equipment. The sludge trap and stabilizer are designed to remove heavy liquids (condensates).

The plant for the production of liquefied natural gas contains two or more parallel processing and liquefaction lines A, B. In accordance with an embodiment of the invention, the plant for the production of liquefied natural gas 1 contains three or more parallel processing and liquefaction lines, for example, four or six parallel processing lines and liquefaction. The term "parallel" is used to mean that lines are arranged in parallel to process portions of a contaminated natural gas feed stream. However, there can be integration between the parallel processing and liquefaction lines A, B, for example, due to the presence of common refrigerant circuits, common functionality of auxiliary services, common means of refrigerant preparation.

The respective treatment and liquefaction lines A, B comprise an inlet 11 for receiving a portion of the feed stream 10 ', 10' 'of the contaminated natural gas feed. The inlet 11 may be in fluid communication with the pre-treatment unit 2 described above.

The respective treatment and liquefaction lines A, B may further comprise a gas treatment stage 12. The gas treatment stage is configured to receive the corresponding part 10 ', 10' 'of the contaminated natural gas stream 10 and remove certain contaminants therefrom. The gas treatment stage 12 may comprise one or more of the following gas treatment units:

- an acid gas removal unit (AGRU) for removing acid components, CO ₂ and / or H ₂ S, an acid gas removal unit containing separation equipment such as an absorption column, a regeneration column including reboilers, condensers and other heat exchangers, wherein the absorption tower and the regeneration tower contain internals such as trays or packings (structured / arbitrary),

- a dehydration unit for removing H ₂ O, and

- mercury removal unit for mercury removal.

The Acid Gas Removal Unit (AGRU) can also remove aromatics (co-absorption) to help achieve benzene / aromatics liquefaction specifications.

Gas treatment stages 12 comprise an outlet for discharging a purified natural gas stream 13. Gas treatment stages 12 may also comprise one or more outlets for respective polluted gas streams 36. Corresponding treatment and liquefaction lines A, B comprise a cooling stage 14 in fluid communication with the outlet of the gas treatment stage 12 for receiving a stream 13 of purified natural gas.

Cooling stage 14 is equipped to cool and optionally liquefy at least a portion of the resulting purified natural gas stream 13. Refrigeration stage 14 can include any suitable refrigeration process, such as a Single Mixed Refrigerant (SMR) process, a Double Mixed Refrigerant (DMR) process, a cascade process, a C3MR process, LiquefinTM process ^; and expansion-based cooling processes. It will be understood that any suitable cooling process can be applied. Parallel processing and liquefaction lines A, B do not necessarily have the same refrigeration process.

By way of example, in FIG. 1 schematically illustrates a refrigeration process including a first refrigeration unit 15, for example, using a first refrigerant, and a second refrigeration unit 17, using a second refrigerant. The first refrigerant can be the first mixed refrigerant and the second refrigerant can be the second mixed refrigerant (DMR process). Alternatively, the first refrigerant can be a single component refrigerant (usually propane) and the second refrigerant can be a second mixed refrigerant (SMR process).

Depending on the cooling process and operating parameters, the cooling stage 14 cools and liquefies at least a portion of the purified natural gas stream 13 or cools at least a portion of the purified natural gas stream 13, while the phase transition to liquid occurs downstream, for example, in the final flash gas installation (described below).

The first cooling unit 15 is configured to generate a pre-cooled purified natural gas stream 151. The second cooling unit 17 is configured to generate an additional cooled stream 171 (at operating temperature). The additional cooled stream can be substantially liquid (ie, more than 99 mol% liquid) at the pressure at the outlet of the second cooling unit 17 ("Main Cryogenic Heat Exchanger" (MCHE)). In the treatment and liquefaction line (s) A, containing the final flash gas unit 18 (as will be described in more detail below), the conditions of the additional chilled stream 171 'are selected so as to obtain a liquefied natural gas stream 184 and a final flash gas stream 182 by depressurizing and separation of liquid and vapor phases (this process is described in more detail below). In the treatment and liquefaction line (s) B (line not containing the final flash gas installation), the conditions of the additional chilled stream 171 "are selected to produce a liquefied natural gas stream 186. The liquefied natural gas stream 186 is substantially liquid. Here, the vapor phase can be separated from the liquefied natural gas stream 186 in the LNG storage tank 100. This vapor is commonly referred to as boil-off gas (BOG). This process is commonly referred to as the flash gas reservoir. The additional chilled stream 171 '' may be a subcooled liquid prior to the pressure drop and typically may contain, for example, about 1-3 mol% steam after the pressure drop. This steam will be separated, for example, in an LNG storage tank 100.

It will be understood that there are many variations, which are typically the amount of steam generated and the location where the steam is generated (in the LNG storage tank 100 or in the final flash gas unit 18).

Although the blocks are schematically illustrated as separate blocks, it should be understood that the first and second cooling blocks 15, 17 can be combined. For example, a second (mixed) refrigerant may be passed through the first chiller 15 to pre-cool with the first (mixed) refrigerant.

In accordance with embodiments of the invention, refrigeration stage 14 comprises an extraction unit 16 (also known as a NGL recovery unit) for recovering natural gas liquids 161 from a purified natural gas stream 13. Natural Gas Liquids (NGL) are hydrocarbon molecules having two or more carbon atoms (C ₂ ⁺ molecules) such as ethane, propane, etc.

In accordance with an embodiment of the invention, schematically illustrated in FIG. 1, the gas condensate liquids recovery unit 16 is located between the first and second cooling units 15, 17. Therefore, the gas condensate liquids recovery unit 16 is configured to receive a precooled stream of purified natural gas 151 from the first cooling unit 15. However, other schemes are also possible, for example, in depending on the cooling process and gas composition.

The gas condensate liquid recovery unit 16 can be a wash column or any other suitable separator, including a flash tank. A suitable NGL recovery unit 16 depends on the liquid content of the feed gas. For example, pipeline gas usually contains few NGLs, while associated gas usually contains large amounts of NGLs.

The NGL recovery unit 16 produces a natural gas liquid stream 161, which may also be referred to as a C ₂ ⁺ rich stream 161. The term enriched C ₂ ^{+ is} used to indicate that the stream is enriched in C ₂ ⁺ molecules compared to the stream obtained by the NGL recovery unit 16, in this embodiment the stream is a pre-cooled purified natural gas stream 151.

The liquefied natural gas stream 161 may be passed to a fractionation unit containing a fractionation column or a series of fractionation columns (demethanizer, deethanizer, depropanizer, etc.) to further separate natural gas components in liquid stream 161. The fractionation unit used may generate a stream, methane-rich and ethane-rich stream. The methane-rich stream is enriched in methane compared to the LNG stream 161. The ethane-rich stream is enriched in ethane compared to the LNG stream 161.

Some components may be kept separately for separate sale or to replenish the refrigerant; other components can be fed back to refrigeration stage 14, such as methane, which was supplied with the liquefied natural gas stream 161.

In accordance with an embodiment of the invention, the additional feed stream may comprise an additional stream containing at least a portion of one or more methane-rich streams generated by respective fractionation units of the respective treatment and liquefaction lines (A, B).

In accordance with an embodiment of the invention, the additional feed stream may comprise an additional stream comprising at least a portion of one or more ethane-rich streams generated by respective fractionation units of the respective treatment and liquefaction lines (A, B).

Advantageously, the methane-rich streams and the ethane-rich streams are at significant pressures, typically in the range 20-30 bar abs, e.g. 25 bar abs, therefore relatively little compression is required to feed the additional liquefaction line C.

The NGL recovery unit 16 further releases a light natural gas stream 162, in fact a stream received by the NGL recovery unit 16, without the LNG stream 161, wherein the light natural gas stream 162 must be at least partially cooled by the second refrigeration unit 17 and at least is partially liquefied to produce liquefied natural gas 181. Light natural gas stream 162 may also be referred to as C ₁ rich stream 162.

The term "enriched in C _{1" is} used to indicate that the stream is enriched in C ₁ molecules (methane) compared to the stream obtained by the NGL recovery unit 16, in this embodiment the stream is a pre-cooled purified natural gas stream 151.

Corresponding processing and liquefaction lines A, B contain an outlet 181 for the release of liquefied natural gas. According to an embodiment of the invention, schematically illustrated in FIG. 1, LNG streams 181 discharged through outlets 181 are collected in LNG storage tank 100. However, it should be understood that more than one LNG storage tank 100 may be present, and not all lines are necessarily connected to all LNG storage tanks 100.

LNG plant 1 contains an additional liquefaction line C.

Additional liquefaction line C can be added as a retrofit to an existing LNG plant 1 or can be part of an original LNG plant design. In particular, the retrofit can be useful in situations where there is excess capacity at the warm end, that is, in the NGL recovery unit 16 and upstream of it, which can, for example, occur when the composition of the feed gas changes, for example with less CO ₂ content or as a result of (partial) replacement of equipment for the separation of the acid gas removal unit (as described above) and / or retrofitting / expansion of other equipment of the acid gas removal unit, such as heat exchangers, providing higher throughput in the gas treatment stage 12 It is understood that the replacement of equipment for the separation of the acid gas removal unit, in particular the replacement of the internals of the absorption tower and / or the replacement / expansion of smaller equipment, is a relatively cost effective way of increasing the productivity of the gas treatment stage 12 when the acid gas removal unit is the limiting part of the o gas processing 12.

In addition, retrofitting can be beneficial if the existing LNG plant was originally redesigned.

It is noted that the additional liquefaction line C preferably does not provide for gas treatment, i. E. does not contain an acid gas removal unit, a dehydration unit, a mercury removal unit and a joint absorption unit, and an additional liquefaction line, in addition, it does not provide for the recovery of gas condensate liquids.

According to an embodiment of the invention, the additional liquefaction line C contains fewer gas treatment units than lines A, B. for treatment and liquefaction. For example, in the case where the treatment and liquefaction lines A, B contain four gas treatment units, for example, an acid gas removal unit (AGRU), a dehydration unit, a mercury removal unit and a co-absorption unit, while the additional liquefaction unit contains no more than its subsets (three or less gas purification units).

The additional liquefaction line contains an additional refrigeration stage 214 to receive and liquefy additional feed stream 210, thereby generating additional liquefied natural gas. Additional refrigeration stage C can reuse any suitable refrigeration process, such as the examples presented above, and can be the same or different from the refrigeration processes included in the treatment and liquefaction lines A and B.

In accordance with the embodiment illustrated in FIG. 1, the additional liquefaction line C contains a refrigeration stage similar to the above-described processing and liquefaction lines A, B, that is, contains a first refrigeration unit 215 for generating pre-cooling of the natural gas stream 2151, and the second refrigeration unit 217 is configured to generate additional refrigerated flow 2171. The second cooling unit 217 is configured to directly receive the pre-cooled purified natural gas stream 2151 from the first cooling unit 215.

The additional liquefaction line C optionally comprises an end flash unit 218 that is configured to receive additional cooled stream 2171 and discharge the flash gas stream 282 and the liquid natural gas stream 284 through outlet 281.

The additional liquefaction line C receives an additional feed stream 210, which contains at least two side streams 163 taken from the respective light natural gas streams 162 withdrawn by NGLs 16 from one or more parallel processing and liquefaction lines (A, B). At least two side streams 163 are substantially gaseous. Depending on the pressure of the at least two side streams 163, side streams 163 may pass through a collection and compression unit 202, described in more detail below. The second refrigeration unit 217 can directly receive the pre-cooled purified natural gas stream 2151 from the first refrigeration unit 215, since NGLs 161 have already been removed from the additional feed stream 210 by NGLs recovery units 16 of the respective treatment and liquefaction lines A, B.

The additional liquefaction line C can be a stand-alone line, that is, it is separate from the lines A, B for processing and liquefaction. However, an additional liquefaction line C can also be integrated with one or more treatment and liquefaction lines A, B, for example by sharing refrigerant pickup, ancillary services, etc.

In accordance with an embodiment of the invention, one or more parallel processing and liquefaction lines (A) comprise an end evaporation unit 18 configured to receive and vaporize gas from at least a portion of the additional cooled stream 171 to generate an end flash gas stream 182 and a liquefied natural gas stream 184. The final flare gas stream 182 is substantially gaseous. The liquefied natural gas stream 184 is substantially liquid. The additional feed stream 210 may further comprise at least a portion of one or more flash gas streams 182 generated by respective flash gas end modules 18 by one or more parallel processing and liquefaction lines (A).

The final evaporator block 18 may be located downstream of the refrigeration stage 14 and is configured to receive (a portion of) the additional refrigerated stream 171.

FIG. 1 illustrates one line with an end flash gas block 18 and one line without an end flash gas block 18, but it should be understood that any number of parallel processing and liquefaction units available may contain an end flash unit 18, but also may not include any unit or include all blocks.

In addition to the exclusive use of side streams 163 taken from the respective light natural gas streams 162 from the NGL recovery unit 16, a final flashing gas 182 may additionally be used. Any suitable portion of the final flashing gas stream 182 in the range of 0% or more may be used in use. up to 100%. A portion of the final flash stream 182 not supplied to the additional liquefaction line C may be used as fuel or may be burned.

In accordance with an embodiment of the invention, all of the flash gas streams 182 of one or more treatment and liquefaction lines A containing the final flash gas block 18 contain an additional feed stream. In accordance with an embodiment of the invention, all flash gas streams 182 of all treatment and liquefaction lines A containing the final flash gas block 18 constitute an additional feed stream.

Since the flash gas streams 182 are already relatively clean and lean, the additional liquefaction line C does not require (all) gas treatment stages or NGL recovery.

In accordance with an embodiment of the invention, the flash gas streams 182 first pass through the respective cooling stages of the treatment and liquefaction lines A, where they are produced for cold reduction purposes, before being (partially) transferred to an additional liquefaction line C.

The various streams to be added by the additional feed stream 210 may not all be at the same pressure and may (not all) be at the correct pressure. This is in particular the case where the additional feed stream 210 also contains (a portion of) the flash gas streams 182, since the flash gas streams are typically at relatively low pressures, such as close to ambient pressure.

In accordance with an embodiment of the invention, the plant for the production of liquefied natural gas 1 comprises a collection and compression unit 202 containing a plurality of inlets for receiving respective streams to be added by an additional feed stream 210. The collection and compression unit 202 is configured to pressurize and combine various streams for the formation and release of an additional feed stream.

The collection and compression unit 202 may comprise a single or multi-stage compressor 203, optionally with internal and / or additional refrigerant (not shown), to compress the streams to be added by the additional feed stream to a predetermined additional feed pressure. Compressor 203 may have one or more inlets to allow inflow of streams at different pressures.

In a further embodiment, the compressor drive 203 is mechanically or electrically coupled to the drive of one or more refrigerant compressors on line C. The additional liquefaction line C may comprise one or more refrigerant compressors for compressing refrigerant that are part of a refrigeration circuit, as will be appreciated by one skilled in the art. this area. The combination of compressors with a drive (fewer drives than the number of compressors) allows better matching of the drive (s) power to the compressor (s) power, especially if the drives are gas turbines, thereby benefiting from the savings from using fewer larger drives. occupying the same capacity of an additional liquefaction line.

In a further embodiment of the invention, the additional feed pressure (stream 210) is selected such that the compressor capacity for compressor 203 and the refrigerant compressor capacity for additional cooling stage 214 are selected to match the drive and compressor capacities.

The additional feed pressure can be selected significantly higher than the pressure of the contaminated natural gas feed stream 10 for the processing and liquefaction lines A, B. Since it is preferred that the additional line C does not require the extraction of gas condensate liquids, there is no pressure, limited / taken into account in connection with the extraction of gas condensate liquids. NGL recovery typically occurs at a predetermined pressure, typically in the range of 30-60 bar abs, eg 50 bar abs, depending on the optimum conditions for performing NGL recovery for a particular stream composition. The recovery of gas condensate liquids is preferably carried out at a relatively low pressure, while liquefaction can usually be carried out more efficiently at a relatively higher pressure. These two effects need to be balanced. The lack of recovery of gas condensate liquids in the additional liquefaction line C eliminates this balancing and provides a more optimal pressure for liquefaction.

The relatively high pressure in the NGLs of the A, B treatment and liquefaction lines minimizes the need to (re) compress two or more side streams (163) taken from the respective light natural gas streams (162) that will be contained in the additional feed stream. ...

In accordance with an embodiment of the invention, the additional feed pressure of the additional feed stream 210 may be more than 10 bar higher than the feed pressure of the contaminated natural gas feed stream 10, more preferably even more than 20 bar higher. Higher additional feed pressure contributes to more efficient cooling and liquefaction of the additional feed stream.

One or more compressors may be suitable for compressing streams that must be added by an additional feed stream to a pressure that is 10 bar or even more than 20 bar higher than the supply pressure at which the contaminated natural gas feed stream (10, 10 ', 10``) is adopted by parallel processing and liquefaction lines (A, B).

In embodiments in which the supplemental feed stream 210 contains at least a portion of one or more flash gas streams 182, the supplemental feed stream 210 may be relatively nitrogen rich.

In accordance with an embodiment of the invention, a plant for the production of liquefied natural gas comprises a nitrogen removal stage (not shown), the nitrogen removal stage being configured to receive one or more streams, which should consist of an additional feed stream, and release one or more streams depleted nitrogen.

A nitrogen removal stage (also called a nitrogen removal unit) may be included in an additional liquefaction line C, may be contained in a collection and compression unit 202, or may be integrated between the final flash gas unit 18 and upstream of the collection and compression unit 202 / additional line liquefaction C. In the latter embodiment of the invention, there is preferably a single nitrogen removal stage for treating all of the flash gas end streams to be added to the additional feed stream 210. The nitrogen removal stage comprises an outlet for discharging one or more nitrogen-depleted streams, wherein the outlet is in fluid communication with the collection and compression unit 202.

However, the use of an additional liquefaction system, as described, may be particularly suitable in situations where the contaminated natural gas stream 10 has a low nitrogen content, which eliminates the need for a nitrogen removal stage as an additional treatment step, i. E. remove the requirement for the nitrogen removal stage to contain an additional liquefaction line C or be located upstream.

In accordance with an embodiment of the invention, the natural gas feed stream 10 preferably has a nitrogen content of less than 1.0 mol% or less than 0.5 mol%.

In particular, the nitrogen content in a portion of the contaminated natural gas feed stream 10 'supplied to the treatment and liquefaction line A containing the final evaporation unit 18 is preferably less than 0.5 mol%, while the nitrogen content in a portion of the contaminated natural gas feed stream natural gas 10 ″ supplied to the treatment and liquefaction line B, not containing the final evaporator unit 18, is preferably less than 1.0 mol%.

FIG. 1 further illustrates a fuel block 300. Fuel block 300 is illustrated schematically and includes a fuel inlet 301 to receive a fuel stream comprising a by-stream 32 from a contaminated natural gas feed stream 10. Fuel block 300 is configured to burn a fuel stream to generate energy (electricity ) for supplying power or energy (heat) to the LNG plant 1, including in particular gas turbine drives for refrigerant compressors, gas turbine generators for power generation, fuel for heat transfer furnace / steam boilers, pilot flares and for supplying fuel in case of heat demand, in particular in the gas treatment stage 12 when heat may be required. FIG. 1 illustrates portions of a liquefied natural gas plant requiring power from a fuel unit 300, schematically indicated by electricity consumers 302.

The fuel stream contains at least a portion 32 of the contaminated natural gas feed stream 10. Preferably, at least 50% of the fuel stream is formed by a side fuel stream 32 from the contaminated natural gas feed stream 10, a portion 34 of the final flash gas stream 182 and / or a portion of the stream purified natural gas 13.

In accordance with an embodiment of the invention, a method is proposed for retrofitting a plant for the production of liquefied natural gas, including at least two or more first liquefaction lines A, B located in parallel with an additional liquefaction line C. After the completion of the modernization, the plant for liquefying natural gas 1 can operate at a rate for the contaminated natural gas feed stream 10 that is withdrawn by pretreatment unit 2, which can be increased relative to the flow rate for the contaminated natural gas feed stream 10 prior to upgrading (i.e., without additional line C).

Preferably, the side fuel stream is taken from the polluted natural gas stream 10. However, in situations where the polluted natural gas feed contains relatively large amounts of H ₂ S, the side fuel stream is preferably taken from the purified natural gas stream 13.

In accordance with an embodiment, the plant for the production of liquefied natural gas comprises at least four or more parallel processing and liquefaction lines (A, B).

Each of the processing and liquefaction lines preferably has a capacity of at least 2 million tons per year, preferably at least 3 million tons per year (MMTG: million metric tons of LNG per year). Thus, an additional liquefaction line (C) can have a capacity of at least 2 million tonnes per year to benefit from large scale economies.

In addition, in the case where an additional liquefaction line is added to an existing natural gas liquefaction plant having at least four or more, for example six, parallel processing and liquefaction lines with the aforementioned capacity, a sufficiently large additional feed stream can be generated without the need for modification. operating parameters of existing parallel processing and liquefaction lines.

In accordance with an embodiment of the invention, a method is proposed for retrofitting an existing liquefied natural gas plant to increase its liquefied natural gas production capacity. The resulting LNG plant can be called a modified LNG plant.

An existing plant for the production of liquefied natural gas (1) may contain two or more parallel processing and liquefaction lines (A, B), as described above, which are configured to:

- take a portion of the contaminated natural gas feed stream (10 ', 10' '),

- remove contaminants from the corresponding part of the contaminated natural gas feed stream (10 ', 10' '), thereby generating a stream of purified natural gas (13),

- to cool at least part of the stream of purified natural gas (13) and to extract liquid natural gas (161) from the stream of purified natural gas (13), as a result of which a stream of light natural gas (162) is formed, which at least partially will be an additional stage cooling (14).

The retrofitting method includes:

- providing an additional liquefaction line (C), and the additional liquefaction line contains an additional cooling stage designed to receive and liquefy the additional feed stream (210), thereby generating additional liquefied natural gas. The additional liquefaction line may be as described above, that is, it may not include the recovery of gas condensate liquids and / or gas treatment.

The retrofitting method includes:

- fluid coupling of an additional liquefaction line (C) with two or more of the light natural gas streams (162) two or more of the processing and liquefaction lines (A, B) to obtain side streams (163) from two or more light natural gas streams gas must be added to an additional feed stream (210).

If an existing LNG plant contains one or more parallel processing and liquefaction lines (A) containing an end evaporation unit (18), as described above, the retrofit method may include:

- linking by fluid an additional liquefaction line (C) with one or more of the final streams of flash gas (182) to receive at least a portion thereof, which is to be added by the additional feed stream (210).

The retrofit method can include:

- providing a collection and compression unit (202) containing a plurality of inlets for receiving corresponding streams to be added by an additional feed stream from two or more parallel processing and liquefaction lines (A, B), a collection and compression unit containing one or more compressors to compress the streams to be added by the additional feed stream to a predetermined additional feed pressure and to combine the streams to be added by the additional feed stream to form an additional feed stream, a collection and compression unit (202) further comprising an outlet for the release of the additional feed flow (210),

- fluid bonding of the respective inputs of the collection and compression unit (202) with two or more parallel processing and liquefaction lines (A, B) and the outlet of the collection and compression unit (202) fluidly connected to an additional liquefaction line (C).

The respective inlets of the collection and compression unit are in fluid communication with those streams of parallel processing and liquefaction lines from which gas is withdrawn for addition to the additional feed stream 210.

In accordance with an embodiment of the invention, an existing LNG plant comprises a fuel block (300), the fuel block (300) being configured to receive and burn a fuel stream, thereby generating energy and / or heat to provide a LNG plant. gas (1) with the production of energy and / or heat,

the retrofitting method includes

- fluid bonding of the fuel unit (300) for receiving a side stream (10) of contaminated natural gas or a stream (13) of purified natural gas.

An existing LNG plant may include a liquid fuel connection between the fuel block and associated parallel processing and liquefaction lines, such as between the fuel block and the end streams of flash gas (182), to provide fuel to the fuel block. The retrofitting method may include disconnecting this fuel connection. The retrofit method may also include leaving the existing fuel connection in place, but in use, the flow rate through the existing fuel connection will be significantly reduced compared to the prior retrofit, typically reduced by more than 50%.

As described above, the gas treatment and liquefaction line may comprise a first cooling unit 15 and a second cooling unit 17, a second cooling unit generating an additional cooled stream 171 at an operating temperature, the operating temperature of the processing and liquefaction lines A, B being substantially the same before and after retrofitting. ... The term "substantially equal" is used herein to mean that operating temperatures differ by less than 4 ° C, preferably by less than 2 ° C.

After the upgraded LNG plant has been installed, the upgraded LNG plant can be operated with the method of operation including:

- receiving appropriate portions of natural gas feed streams (10 ', 10' ') at a feed pressure and

- increasing the pressure in the additional feed stream to the additional supply pressure, which must be at least 10 bar higher than the supply pressure,

- supply of an additional feed stream to an additional liquefaction line (C).

In accordance with an embodiment of the invention, the additional feed pressure of the additional feed stream 210 may be 10 bar higher than the feed pressure of the contaminated natural gas feed stream 10, more preferably even more than 20 bar higher. Higher additional feed pressure contributes to more efficient cooling and liquefaction of the additional feed stream.

The present disclosure is not limited to the embodiments of the invention as described above and the appended claims. Many modifications are possible, and features of respective embodiments of the invention may be combined.

Additional embodiments of the invention

In accordance with another embodiment of the invention, there is provided a liquefied natural gas plant (1) for producing liquefied natural gas from a contaminated natural gas feed stream (10), a liquefied natural gas plant (1) comprising one or more parallel processing lines, and liquefaction (A, B), characterized in that the corresponding processing and liquefaction lines (A, B) include:

- inlet (11) for receiving part of the feed stream of contaminated natural gas (10 ', 10' '),

- a gas treatment stage (12) for removing impurities from the corresponding part of the feed stream of contaminated natural gas (10 ', 10' '), resulting in the formation of a stream of purified natural gas (13),

- a cooling stage (14), designed to receive a stream of purified natural gas (13) from a gas treatment stage (12) for cooling at least part of a stream of purified natural gas (13), and the cooling stage (14) contains a device (16) for recovering liquefied natural gas to extract liquids from natural gas (161), thereby generating a light natural gas stream (162) which is at least partially further cooled in a refrigeration stage (14) to at least partially liquefy and

- outlet (181) for the production of liquefied natural gas,

moreover, the plant for liquefied natural gas (1) contains an additional liquefaction line (C), and the additional liquefaction chain contains:

- inlet (211) for receiving additional feed stream (210),

- an additional cooling stage (214), designed to receive an additional feed stream to cool the additional feed stream (210), resulting in the formation of additional liquefied natural gas, and

- release (281) for the release of additional liquefied natural gas (284),

wherein the additional feed stream (210) contains one or more side streams (163) taken from respective light natural gas streams (162) of one or more parallel processing and liquefaction lines (A, B).

According to a further embodiment of the invention, a method is provided for retrofitting an existing liquefied natural gas plant to increase production capacity for liquefied natural gas, wherein the existing liquefied natural gas plant (1) comprises one or more parallel processing and liquefaction lines (A, B ) for the production of liquefied natural gas from the feed stream of contaminated natural gas (10), and one or more parallel processing and liquefaction lines (A, B) are located so that:

- take a portion of the contaminated natural gas feed stream (10 ', 10' '),

- remove contaminants from the corresponding part of the contaminated natural gas feed stream (10 ', 10' '), thereby generating a stream of purified natural gas (13),

- to cool at least a part of the purified natural gas stream (13) and the recovery of natural gas liquids (161), thereby generating a light natural gas stream (162), which is at least partially further cooled in the cooling stage (14),

moreover, the conversion method includes:

- provision of an additional liquefaction line (C), where the additional liquefaction line contains an additional cooling stage designed to receive and liquefy an additional feed stream (210) to generate additional liquefied natural gas,

- fluid coupling of an additional liquefaction line (C) with one or more light natural gas streams (162) of one or more processing and liquefaction lines (A, B) to obtain side streams (163) of one or more light natural gas streams, which must be added to the additional feed stream (210), thereby forming a modernized LNG plant.

In accordance with a further embodiment of the invention, there is provided a method for operating a modified plant for the production of liquefied natural gas (1) in accordance with the foregoing or provided in accordance with the method or upgrade presented above, the method comprising:

- operation of one or more parallel processing and liquefaction lines (A, B), whereby the operation of one or more parallel processing and liquefaction lines (A, B) provides for the reception of the corresponding parts of the feed streams of contaminated natural gas (10 ', 10' ') of one or several parallel processing and liquefaction lines (A, B) at supply pressure and

- operation of an additional liquefaction line (C), and the operation of an additional liquefaction line (C) includes the supply of an additional feed stream containing one or more streams of light natural gas (163) taken from one or more parallel processing and liquefaction lines (A, B) wherein the additional feed stream is supplied at an additional feed pressure that is at least 10 bar higher than the feed pressure.

It is recognized that an additional liquefaction line can also be added to one processing and liquefaction line. The additional feed stream may contain any combination of the above disclosed streams taken from (single) processing and liquefaction lines, such as a final flash gas production line.

Claims (34)

1. Installation (1) for the production of liquefied natural gas for the production of liquefied natural gas from the feed stream (10) contaminated natural gas, and the specified installation (1) for the production of liquefied natural gas contains two or more parallel lines (A, B) processing and liquefaction located in parallel in the technological sections of the feed stream (10) of contaminated natural gas, with each line (A, B) processing and liquefaction contains: - inlet (11) for receiving a part (10 ', 10' ') of the feed stream (10) of contaminated natural gas, - a gas treatment stage (12) for removing contaminants from the corresponding part (10 ', 10' ') of the contaminated natural gas feed stream (10), thereby generating a purified natural gas stream (13), - a cooling stage (14) configured to receive a stream (13) of purified natural gas from a gas treatment stage (12) for cooling at least part of a stream (13) of purified natural gas, and the cooling stage (14) comprises a block (16) recovering gas condensate liquids to recover gas condensate liquids (161), thereby generating a light natural gas stream (162), which is at least partially further cooled in a cooling stage (14) to at least partially liquefy; and - release (181) for the production of liquefied natural gas (184, 186), moreover, the installation (1) for the production of liquefied natural gas contains at least one additional liquefaction line (C), and the specified additional liquefaction line contains: - inlet (211) for receiving additional feed stream (210), an additional cooling stage (214) configured to receive an additional feed stream (210) to cool the additional feed stream (210), thereby generating additional liquefied natural gas (284), and - release (281) for the release of additional liquefied natural gas (284), wherein the additional feed stream (210) contains at least two or more side streams (163) taken from the respective light natural gas streams (162) from two or more parallel processing and liquefaction lines (A, B). 2. Installation (1) for the production of liquefied natural gas according to claim 1, characterized in that one or more parallel lines (A) for processing and streams of light natural gas for generating the final flash stream (182) and liquefied natural gas (181), and the additional feed stream (210) additionally contains at least part of one or more flash streams (182) generated by the respective final flash units (18) ... 3. Installation (1) for the production of liquefied natural gas according to any one of paragraphs. 1 or 2, characterized in that it comprises a collection and compression unit (202) containing a plurality of inlets for receiving respective streams to be included in an additional feed stream (210), the collection and compression unit (202) being configured to create pressure and combining different streams to form and release additional feed stream. 4. Installation (1) for the production of liquefied natural gas according to any one of paragraphs. 1-3, characterized in that it contains a nitrogen removal stage, said nitrogen removal stage being configured to receive one or more streams to be included in the additional feed stream and discharge one or more nitrogen-depleted streams. 5. Installation (1) for the production of liquefied natural gas according to any one of paragraphs. 1-4, characterized in that it comprises a fuel block (300) comprising a fuel inlet (301) for receiving a fuel stream, said fuel stream comprising a side stream from a contaminated natural gas stream (10). 6. Installation (1) for the production of liquefied natural gas according to any one of paragraphs. 1-5, characterized in that it contains at least four or more parallel processing and liquefaction lines (A, B). 7. A method for upgrading an existing LNG plant to increase its LNG production capacity, while the existing LNG plant (1) contains two or more parallel processing and liquefaction lines (A, B) for the production of liquefied natural gas. natural gas from the contaminated natural gas feed stream (10), wherein two or more parallel processing and liquefaction lines (A, B) are arranged in parallel to treat portions (10) of the contaminated natural gas feed stream, and each of them is configured to: - receive part (10 ', 10' ') of the stream (10) of contaminated natural gas, - remove pollutants from the corresponding part (10 ', 10' ') of the stream (10) of polluted natural gas, as a result of which a stream (13) of purified natural gas is formed, - to cool at least a part of the stream (13) of purified natural gas and to carry out the extraction of gas condensate liquids (161), thereby generating a stream (162) of light natural gas, which is at least partially further cooled in the cooling stage (14), moreover, the modernization method includes the stages: - providing an additional liquefaction line (C), said additional liquefaction line comprising an additional cooling stage (214) configured to receive and liquefy an additional feed stream (210) to generate additional liquefied natural gas (284), - linking by fluid an additional liquefaction line (C) with two or more light natural gas streams (162) of two or more processing and liquefaction lines (A, B) to obtain side streams (163) of two or more light natural gas streams, which must be included in the additional feed stream (210), thereby forming a modernized plant for the production of liquefied natural gas. 8. A modernization method according to claim 7, characterized in that the existing plant for the production of liquefied natural gas contains one or more parallel processing and liquefaction lines (A) containing an end evaporation unit (18), and the modernization method includes: - fluid communication of the additional liquefaction line (C) with one or more of the final evaporation streams (182) to receive at least a portion thereof to be included in the additional feed stream (210). 9. The method of modernization according to any one of paragraphs. 7, 8, which includes: - providing a collection and compression unit (202) containing a plurality of inlets for receiving respective streams to be included in the additional feed stream from two or more parallel processing and liquefaction lines (A, B), said collection and compression unit comprising one or several compressors for compressing the streams to be included in the additional feed stream to a predetermined pressure of the additional feed and combining the streams to be included in the additional feed stream to form an additional feed stream, said collection and compression unit (202) additionally contains an outlet for the release of an additional feed stream (210), - fluid coupling of the respective inlets of the collection and compression unit (202) with two or more parallel processing and liquefaction lines (A, B) and fluid coupling of the outlet of the collection and compression unit (202) with an additional liquefaction line (C). 10. The method of modernization according to any one of paragraphs. 7-9, characterized in that the existing installation for the production of liquefied natural gas contains a fuel block (300), and the specified fuel block (300) is configured to receive and burn a fuel stream, thereby generating energy and / or heat to provide the installation ( 1) for the production of liquefied natural gas with energy and / or heat, at the same time, the modernization method includes the stage: fluid bonding of a fuel unit (300) for receiving a side stream of a contaminated natural gas feed stream (10) or a purified natural gas stream (13). 11. The method of operation of the installation (1) for the production of liquefied natural gas according to any one of paragraphs. 1-6 or provided by the method according to any one of claims. 7-10, and the method includes the stages at which: - carry out the operation of two or more parallel lines (A, B) of treatment and liquefaction, whereby the operation of two or more parallel lines (A, B) of treatment and liquefaction provides for the receipt of the corresponding parts (10 ', 10' ') of the feed stream (10) contaminated natural gas by two or more parallel lines (A, B) for processing and liquefying at feed pressure and parallel processing of said portions (10 ', 10' ') of the contaminated natural gas feed stream (10), and - operate an additional liquefaction line (C), while the operation of the additional liquefaction line (C) provides for the provision of an additional feed stream (210) containing at least two or more streams (163) of light natural gas taken from two or more parallel lines (A, B) for processing and liquefaction, and the additional feed stream (210) is provided at a pressure of the additional feed that is at least 10 bar higher than the specified feed pressure.

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