ES2414029T3 - Method for gasification of a liquid hydrocarbon stream and an apparatus for it - Google Patents

Abstract

A method for the gasification of a liquid stream (5) of hydrocarbons to provide a stream (55) of hydrocarbon gas and energy, comprising at least the steps of: (a) pressurizing a liquid stream (5) of hydrocarbons at a pressure feed to provide a stream (15) of pressurized liquid hydrocarbons at a cold recovery pressure; (b) subjecting the pressurized liquid hydrocarbon stream (15) to heat exchange against one or more steam recycling streams (115) to provide a stream (35) of heated liquid hydrocarbons and one or more liquefied recycling streams (125) ; (c) pass one or more liquefied recycling streams (125), after pressurization if necessary, either or both of the liquid stream (5) of hydrocarbons and the stream (15) of liquefied pressurized hydrocarbons; (d) pressurize one or more parts of the heated liquid hydrocarbon stream (35) to provide one or more streams (45) of pressurized heated liquid hydrocarbons, at least one of which is at a minimum or higher pipeline pressure; (e) vaporize one or more of the streams (45) of pressurized heated liquid hydrocarbons, at least one of which is at the minimum or highest pipe pressure, against one or more sources of heat (345) to provide one or more more hydrocarbon gas streams (55), at least one of which is at the lowest or highest pipe pressure; (f) dynamically expand at least a portion (55, 55a, 55e) of at least one or more hydrocarbon gas streams (55) to provide energy and one or more streams (115) of expanded hydrocarbons, where at least a portion of said one or more streams of expanded gaseous hydrocarbons forms at least a part of one or more steam recycling streams (115).

Description

Method for gasification of a liquid hydrocarbon stream and an apparatus for it

The present invention provides a method for the gasification of a liquid stream of hydrocarbons, such as a stream of liquefied natural gas (LNG), to provide a gaseous stream of hydrocarbons, such as a stream of natural gas and energy, and an apparatus for it. The apparatus and method are particularly suitable for use in a LNG regasification facility.

Normally, LNG is mainly liquefied methane that contains varying amounts of ethane, propane and butanes with trace amounts of pentanes and heavier hydrocarbon components. Normally, LNG contains a low content of aromatic hydrocarbons and non-aromatic hydrocarbons such as H2O, N2, CO2, H2S and other sulfur compounds, because these compounds have been removed, at least partially, before liquefying the gas stream natural, which is subsequently stored and transported in liquid form.

It is desirable to liquefy natural gas for a number of reasons. As an example, natural gas can be stored and transported long distances in liquid form more easily than in gaseous form, because it occupies a smaller volume. It may not be necessary to store it at high pressures. Said liquefied natural gas may be stored at atmospheric pressure if it is maintained at cryogenic temperature, such as at -160 ° C or less. Alternatively, the liquefied natural gas can be stored at temperatures above -160 ° C if it is pressurized above atmospheric pressure.

In order to regasify the LNG stream, it is normally pressurized and vaporized. If desired, a selected amount of one or more additional components, for example nitrogen, can be added to obtain natural gas having a desired gas quality, for example a desired calorific value (ie, energy content when the gas is burned natural), according to gas specifications or consumer requirements. In addition, the calorific value of natural gas can be adjusted to remove or add a desired amount of heavier hydrocarbons from natural gas.

A LNG regasification terminal pressurizes and vaporizes LNG so that pressurized natural gas can be injected into a gas network at room temperature. Although different types of heat exchangers are available to vaporize LNG, a common option is the use of an ambient heat source such as seawater. However, the vaporization of LNG against an ambient heat source represents a loss of energy. For example, for every 1 MTPA (million metric tons per year) of vaporized LNG, a thermal flow of between 20 and 30 MW is lost. This could be used for a number of practical purposes, such as power generation. It would be desirable if this unused thermal flux could be used to generate electricity, making the regasification facility self-sufficient in terms of its energy requirements, so that the entry of energy from an external power grid or combustion was not necessary. of hydrocarbon fuels. A terminal that does not require the direct or indirect combustion of hydrocarbon fuels for its operation will be neutral in terms of carbon dioxide.

WO 2007/011921 discloses a method for generating energy in an LNG regasification facility using LNG. In the disclosed method, natural gas is used as a working fluid where at least a part of the vaporized natural gas is expanded in a turbine to produce energy and expanded vaporized natural gas. The expanded vaporized natural gas is subsequently condensed using cold from the liquefied natural gas, and subsequently combined with liquefied natural gas. Next, the combined condensed and liquefied natural gas is vaporized to produce the vaporized natural gas.

The method of WO 2007/011921 heats the portion of the vaporized natural gas used in the expansion stage to a temperature of 232 ° C (450 ° F) before expansion in the turbine. Although it is said that the disclosed method is capable of generating 5 MW, this cannot be achieved using an ambient heat source, and an additional energy input is required. In order to heat the vaporized natural gas to temperatures of 232 ° C, a heat source such as combustion gas from a gas turbine, a waste heat recovery unit and / or a heated heater is required. All of the aforementioned sources of heat are based, for example, on the combustion of a hydrocarbon fuel and, thus, carbon dioxide emissions occur.

A problem with this known gasification method is that the combustion of hydrocarbons and associated carbon dioxide emissions is required in order to produce enough energy to meet the needs of the regasification facility.

The present invention seeks to address this problem by providing a method for regasifying a liquid hydrocarbon stream that is self-sufficient in terms of energy consumption in the steady state operation and is neutral in terms of carbon dioxide.

In particular, the method and apparatus of the present invention can generate sufficient energy from the gasification process to operate an LNG import terminal where LNG is converted into natural gas for consumption. It is not necessary for said import terminal to produce carbon dioxide emissions that normally come from the generation of electricity necessary to operate the terminal and can be neutral in terms of carbon dioxide emissions, as a result of the generation of energy from the LNG gasification.

It is desirable to minimize carbon dioxide emissions from the facility, and more preferably to eliminate such emissions completely to provide a "zero carbon dioxide emission" regasification method. Such installation would be autonomous in terms of its energy requirements and generate carbon credits as a result of its generation of carbon dioxide-free energy.

In a first aspect, the present invention provides a method for the gasification of a liquid hydrocarbon stream to provide a gaseous stream of hydrocarbons and energy, the method comprising at least the steps of:

(to)

 pressurize a liquid hydrocarbon stream at a feed pressure to provide a pressurized liquid hydrocarbon stream at a cold recovery pressure;

(b)

 subjecting the pressurized liquid hydrocarbon stream to heat exchange against one or more steam recycling streams to provide a heated liquid hydrocarbon stream and one or more liquefied recycle streams;

(C)

pass one or more liquefied recycling streams, after pressurization if necessary, to one or both of the liquid hydrocarbon stream and the pressurized liquefied hydrocarbon stream;

(d)

 pressurize one or more parts of the heated liquid hydrocarbon stream to provide one or more pressurized heated liquid hydrocarbon streams, at least one of which is at a minimum or higher pipeline pressure;

(and)

 vaporize one or more of the pressurized heated liquid hydrocarbon streams, at least one of which is at the minimum or higher pipe pressure, against one or more sources of heat to provide one or more hydrocarbon gas streams, at least one of which is at the minimum or highest pipe pressure;

(F)

 dynamically expanding at least a part of at least one or more hydrocarbon gas streams to provide energy and one or more expanded gas hydrocarbon streams, where at least a portion of said one or more expanded gas hydrocarbon streams forms at least a portion of one or more steam recycling streams.

In another aspect, the present invention provides an apparatus for the gasification of a liquid hydrocarbon stream to provide a gaseous stream of hydrocarbons and energy, said apparatus comprising at least:

-

a liquid hydrocarbon stream pump to pressurize a liquid hydrocarbon stream at a feed pressure to provide a liquefied and pressurized hydrocarbon stream at a cold recovery pressure;

-

a hydrocarbon stream heat exchanger for thermally exchanging the liquid and pressurized hydrocarbon stream against one or more steam recycling streams to provide a heated liquid hydrocarbon stream and one or more liquefied recycling streams;

-

a heated hydrocarbon stream pump to pressurize one or more parts of the liquid and heated hydrocarbon stream to provide one or more pressurized heated liquid hydrocarbon streams, at least one of which is at a minimum or higher pipeline pressure;

-

a source of heat to vaporize one or more of the pressurized heated liquid hydrocarbon streams, at least one of which is at a minimum or higher pipe pressure, to provide one or more hydrocarbon gas streams;

-

a recycling turbine to dynamically expand at least a part of at least one or more of the hydrocarbon gas streams to drive an axis and provide one or more expanded gas hydrocarbon streams, at least a part of which forms at least a part of one or more steam recycling streams; Y

-

one or more hydrocarbon stream mixing devices for introducing one or more liquefied recycling streams, or a stream thereof, into the liquid hydrocarbon stream or the liquefied and pressurized hydrocarbon stream.

A major advantage of the present invention is that the method and the apparatus operate at two levels of pressure. An initial pressurization step (a) is carried out to increase the pressure of the liquid hydrocarbon stream from a feed pressure to provide a liquid and pressurized hydrocarbon stream at a cold recovery pressure.

Cold recovery pressure is the pressure used to carry out the heat exchange of the liquid and pressurized hydrocarbon stream against the steam recycling stream. This heat exchange heats the liquid hydrocarbon stream and liquefies the steam recycling stream.

Subsequently, a second pressurization of the liquid and heated hydrocarbon stream is carried out in step (d) to bring the pressure of at least a part of this stream to a minimum or higher pipe pressure. The minimum pipe pressure can be the pressure of the natural gas network to which the vaporized natural gas must be supplied.

The second pressurization stage (d) allows the heat exchange of stage (b) to be carried out at any desired pressure ("cold recovery") above the feed pressure. This allows the use of an optimal cold recovery pressure of LNG in the heat exchange. In particular, the specific heat capacity of LNG decreases with pressure, so that LNG at low pressures can provide additional cooling capacity compared to an identical composition at a higher pressure. Therefore, it is desirable to carry out the heat exchange of step (b) at a cold recovery pressure that is less than the minimum pipe pressure, in order to provide optimum cooling to one or more of the streams Steam recycling stage (b).

It has been found that cold recovery pressures of less than 60 bar are particularly advantageous. Such pressures can be significantly lower than the minimum pipe pressure, which can be in excess of 60 bar, and commonly up to 85 bar in some countries. The fact of carrying out the step (b) of heat exchange at a pressure lower than the pipe pressure is also advantageous since the heat exchanger can be designed to operate at said lower pressures, reducing CAPEX. Preferably, the cold recovery pressure is less than the critical pressure of the pressurized hydrocarbon stream in order to retain the latent heat capacity of the hydrocarbon for heat exchange. As used herein, the term "critical pressure" is the pressure of the pressurized hydrocarbon stream (or any other appropriate stream) at which the phase boundary between the gaseous and liquid states ceases to exist.

On the contrary, the disclosure of WO 2007/011921 requires the pumping of LNG at the pipeline pressure before the heat exchange against the expanded vaporized natural gas (steam recycling stream). This means that the heat exchange of LNG to liquefy the expanded vaporized natural gas must be carried out at the export pressure of the natural gas (minimum pipe pressure). This does not provide any flexibility of the LNG pressure during the heat exchange stage with the expanded vaporized natural gas, avoiding the optimization of the efficiency of the heat exchange stage.

In addition, step (c) of the present invention adds the liquefied recycle stream to the liquid hydrocarbon stream or the liquid and pressurized hydrocarbon stream. This combination of liquefied streams occurs upstream of the heat exchange stage (b), so that the cold energy provided can be used to liquefy the steam recycling stream in order to further liquefy the natural gas vapor.

In contrast, the disclosure of WO 2007/011921 shows that the expanded and condensed vaporized natural gas is combined with the LNG downstream of the heat exchange stage, so that the cooling operation of the vaporized natural gas is not used expanded condensed in the condensation of the expanded vaporized natural gas stream, which leads to less efficient use of cold LNG energy.

The dynamic expansion of at least a part of at least one or more of the hydrocarbon gas streams of step (f) is used to generate energy. It is preferable that the hydrocarbon gas stream expands to a pressure between 10 and 30 bar in a turbine.

Preferably, the energy produced is generated in the form of electrical energy. The generation of electric power is advantageous because any excess electricity not necessary to operate the gasification facility can be exported to other processing units or to an external electricity network, such as the public electricity network. If the energy is generated in the form of mechanical energy, a transmission system may be necessary to operate the pumps used in the installation.

The heat sources used herein, including any of the hydrocarbon streams generated in the gasification method that are used as heat sources, preferably have a temperature higher than the temperature of the stream to be heated. Preferably, the heat source has a temperature greater than -40 ° C, more preferably greater than -30 ° C, even more preferably within the range of 0 to 30 ° C. In a preferred embodiment, the upper temperature limit of the heat source is substantially room temperature. One or more heat sources may be, for example, one or both of the environmental heat sources such as ambient air or ambient water, and any hydrocarbon stream generated in the gasification method. However, it is possible to integrate the heat source with that of the combined power plant.

Embodiments of the present invention will now be described by way of example and with reference to the non-limiting accompanying drawings in which:

Figure 1 is a diagram of a method and an apparatus for gasifying a liquid hydrocarbon stream according to a first embodiment; Figure 2a is a diagram of a method and an apparatus for gasifying a liquid hydrocarbon stream according to a second embodiment; Figure 2b is a diagram of a method and an apparatus for gasifying a liquid hydrocarbon stream according to a third embodiment; Figure 3 is a diagram of a method and an apparatus for gasifying a liquid hydrocarbon stream according to a fourth embodiment; and Figure 4 is a schematic diagram of a method and an apparatus for gasifying a liquid hydrocarbon stream according to a fifth embodiment.

For the purpose of this description, an individual reference number will be assigned to a pipeline as well as to a stream carried by that pipeline. The same reference numbers used in different Figures represent identical streams and pipes.

As mentioned above, it is often desirable to liquefy hydrocarbon compositions, such as natural gas since it can be stored more conveniently and can be transported long distances in liquid form more simply than in gaseous form. Subsequently, the liquefied natural gas can be regasified in the desired destination and a gas network can be passed under pressure.

Referring to the drawings, Figure 1 shows a method and an apparatus 1 for the gasification of a liquid stream of hydrocarbons. The liquid hydrocarbon stream 5 may comprise a hydrocarbon or mixture of hydrocarbons, such as a stream of liquefied natural gas, or a synthetic hydrocarbon composition, such as that provided by the reaction of a synthesis gas in a Fischer process -Tropsch. Liquefied natural gas can be provided by treating and liquefying natural gas in a manner known in the art.

The liquid hydrocarbon stream 5 is provided at a feed pressure. Conventionally, the liquid hydrocarbon, such as liquefied natural gas, is stored under cryogenic conditions. The liquefied gas can be pressurized at temperatures below 0 ° C or at a temperature of approximately -160 ° C and at or near atmospheric pressure. This storage is discussed in more detail in relation to Figure 2a. The feed pressure of the liquid hydrocarbon stream 5 will depend on the pressure at which the stream is pumped to transport it to the gasification apparatus 1. Preferably, the feed pressure is less than 8 bar, and more preferably within the range of 1 to less than 8 bar.

In step (a), the liquid hydrocarbon stream 5 is passed to the supply pressure to a liquid hydrocarbon pump 10, where it is pressurized to provide a pressurized liquid hydrocarbon stream 15 at a pressure higher than the feed pressure Preferably, the hydrocarbon liquid stream pump 10 is an electric pump. It is intended to increase the pressure of the liquid hydrocarbon stream 5 to a pressure at which the subsequent heat exchange stage has to be carried out - the "cold recovery pressure". Preferably, the cold recovery pressure is within the range of 8 to less than 50 bar, more preferably within the range of 8 to less than 40 bar, even more preferably within the range of 8 to less than 30 bar.

Subsequently, the pressurized liquid hydrocarbon stream 15 is passed to a hydrocarbon stream heat exchanger 30 of step (b), where it is heated against one or more steam recycling streams 115, to provide a liquid stream 35 of hydrocarbons and one or more liquefied recycling streams 125. In the embodiment shown in Figure 1, only a single steam recycling stream 115 and a liquefied recycling stream 125 are shown, although two, three or four or more of each of the streams may be present. When there are two or more steam recycling streams 115, these streams are advantageously provided at different pressures. This embodiment is discussed in more detail in relation to the embodiment of Figure 3.

The hydrocarbon stream heat exchanger 30 may be selected from a cover and tube, a plate and fin and a printed circuit heat exchanger. It is important that the temperature of the liquid and pressurized hydrocarbon stream 15 at the cold recovery pressure does not rise above the bubble point (i.e., the temperature at which the pressurized liquid hydrocarbon stream 15 first produces bubbles vapor) of the composition during heat exchange, in order to ensure that the stream remains liquid, more preferably completely liquid. This is because it is more difficult and less effective to compress a multi-phase vapor / liquid stream than a single phase liquid stream.

The requirement that the pressurized liquid hydrocarbon stream 15 remain liquid in the hydrocarbon stream heat exchanger 30 sets an upper limit on the cooling operation available from the pressurized liquid hydrocarbon stream 15 at a particular recycling pressure in cold. Similarly, it is important that sufficient cooling is provided to steam recycling stream 115

to liquefy, preferably fully liquefy, the steam recycle stream 115, so that a limit is set greater than the amount of steam recycle stream that can be liquefied.

The heated liquid hydrocarbon stream 35 leaves the hydrocarbon stream heat exchanger 30 and one or more parts is passed to a heated hydrocarbon stream pump 40. Preferably, the heated hydrocarbon stream pump 40 is an electric pump. It is preferable that all the liquid and heated hydrocarbon stream 35 be passed to the heated hydrocarbon stream pump 40. The heated hydrocarbon stream pump 40 pressurizes one or more parts of the heated and liquid hydrocarbon stream 35 to provide one or more streams of liquid and heated hydrocarbons, at least one of which is at a minimum or more pipeline pressure. high. Figure 1 shows a stream of pressurized heated liquid hydrocarbons, which will be at or below a minimum pipe pressure.

The part (s) of the heated hydrocarbon stream (s) 45, which is heated and pressurized (s), at the minimum or highest pipe pressure, can be gasified and passed to a gas consumption device. Thus, the "minimum pipe pressure" is the required pipe pressure of the vaporized hydrocarbon consumption device, such as a gas network. This pressurization stage ensures that the part or parts of the pressurized heated liquid hydrocarbon stream 45 which is intended to provide the network gas is / are at a pressure equal to or greater than the pipeline pressure of the gas network. It is significantly more efficient, from the energy point of view, to pressurize a liquid stream to or above the pipeline pressure than to that corresponding to the evaporated gas stream.

One or more of the streams 45 of pressurized heated liquid hydrocarbons, at least one of which is at the minimum or highest pipe pressure, can be passed to one or more of the hydrocarbon stream heaters 50. The hydrocarbon stream heaters 50 are supplied with one or more heat sources 345 to vaporize the heated and pressurized liquid hydrocarbon. Preferably, one or more sources of heat 345 have a temperature less than or equal to room temperature, such as ambient air sources or ambient water, such as a seawater stream. The hydrocarbon stream heaters 50 produce one or more hydrocarbon gas streams, at least one of which will be at the lowest or highest pipe pressure, and a source 355 of cooled heat, such as a cold air stream or cold water, such as seawater. In a preferred embodiment, the hydrocarbon stream heater 50 is an open grid vaporizer (ORV).

In some cases, the upper pressure limit at which the liquid (s) and heated hydrocarbon stream (s) 35 can be pumped is determined by the maximum operating pressure of the current heater 50 of hydrocarbons. Commonly, open-grid vaporizers have a maximum operating pressure of 140 to 150 bar. It is preferable that the pressure of the stream (s) 45 of the heated and pressurized liquid hydrocarbon (s), which is at a minimum or higher pipe pressure, is between the minimum pipe pressure and 140 bar.

In a preferred embodiment, the heated liquid hydrocarbon stream 35 is pressurized to provide the pressurized heated liquid hydrocarbon stream 45 in the form of a supercritical hydrocarbon stream. Under supercritical conditions, the pressurized heated liquid hydrocarbon stream 45 loses its latent heat capacity so that it can be heated more easily.

A device 60 for separating the hydrocarbon gas stream can separate at least one or more hydrocarbon gas streams into two or more parts 55a, 55b. Figure 1 shows the separation of an individual hydrocarbon gas stream 55, which is at or below the minimum pipe temperature, in two parts, a first part 55a and a second part 55b.

The second part, 55b, can be passed to the gaseous hydrocarbon consumption devices. If this is provided above the minimum pipe pressure, then the current pressure can be reduced by means of an appropriate expansion device. The embodiment of Figure 2a provides an example of said pressure reduction using a turbine to generate additional energy.

The first part, 55a, is passed to a recycling turbine 110, where it is dynamically expanded to provide one or more streams 115 expanded hydrocarbon gases. Figure 1 shows a stream 115 of expanded and individual gaseous hydrocarbon.

The recycling turbine 110 converts the useful work released by the dynamic expansion of the first part, 55a of the hydrocarbon gas stream 55 into kinetic energy to rotate the shaft 112 of the electric generator 120. The electric generator can provide electric power to satisfy the needs of the gasification facility. In an alternative embodiment not shown in Figure 1, two or more hydrocarbon gas streams 55 may be provided by means of one or more hydrocarbon stream heaters. A first hydrocarbon gas stream, which is at or above the pipeline pressure, can be passed to a gas network, while a second hydrocarbon gas stream can be passed to the recycling turbine for dynamic expansion

Returning to the embodiment of Figure 1, one or more gas streams 115 of expanded hydrocarbons produced by means of the recycling turbine 110 can be provided at one or more expansion pressures. One or more expansion pressures should be less than the suction pressure of one or more gaseous streams of hydrocarbons passed to the turbine.

The energy that can be generated from the recycling turbine 110 depends, among several factors, on the pressure ratio of the turbine, that is, the ratio of the pressure of the expanded gas hydrocarbon stream 115 with respect to the pressure of part 55a of one or more gaseous streams of hydrocarbons sent to the recycling turbine 110. The gas expansion is more efficient at pressures lower than the supercritical range, so that suction pressures within the range of 60 to 80 bar are preferred .

One or more streams 115 of expanded gaseous hydrocarbons are passed to the hydrocarbon stream heat exchanger 30 in the form of at least a part of one or more steam recycling streams. Preferably, one or more of the steam recycling streams 115 are provided entirely from one or more streams of expanded gaseous hydrocarbons, such that the vapor recycle stream and the expanded gaseous hydrocarbon stream are one and the same . One or more of the steam recycling streams 115 are liquefied in the hydrocarbon stream heat exchanger 30 versus the pressurized liquid hydrocarbon stream 15 to provide a liquefied recycle stream 125. Figure 1 shows the liquefying of an individual steam recycling stream 115 to give an individual liquefied recycling stream 125.

If the liquefied recycling stream 125 produced by means of the hydrocarbon stream heat exchanger 30 is at the supply pressure of the hydrocarbon liquid stream 5, then it can be passed directly to the hydrocarbon liquid stream 5. Said embodiment is discussed in relation to Figure 2a below.

Alternatively, if the pressures of one or more of the liquefied recycle streams 125 are above the feed pressure of the liquid recycle stream 5, then they can be passed to the suction of a

or more of the recycle stream pumps 130. Preferably, one or more of the recycle current pumps 130 are electric pumps. One or more of the recycle pumps 130 pressurize one or more of the liquefied recycle streams 125 to provide one or more pressurized recycled streams 135 pressurized to the cold recovery pressure. Preferably, one or more of the liquefied recycle streams 125 are completely liquefied streams, because the recycle stream pump 130 can operate most effectively with a single phase liquid stream. Instead of using multiple recycle stream pumps 130, when there is more than one liquefied recycle stream 125, a multistage recycle stream pump 130 may be more cost effective. In the embodiment shown in Figure 1, an individual liquefied recycle stream 125 is passed to an individual recycle stream pump 130.

Subsequently, pressurized liquefied recycling streams 135 can be combined with pressurized liquid hydrocarbon stream 15, by means of one or more hydrocarbon stream mixing devices 20, to provide a pressurized liquid hydrocarbon stream 15a, which is a stream combined, and hydrocarbon stream heat exchanger 30 is passed.

In order to maximize the energy that can be generated by means of the electric generator 120, the part 55a of one or more hydrocarbon gas streams 55 that is passed to the recycling turbine 110 should be maximized. Subsequently, a or more of the hydrocarbon gas streams 115 produced by the recycling turbine 110, so that they can be recycled. The part of one or more of the gaseous hydrocarbon streams 55 that can be recycled depends on the cooling operation available in the heat exchanger 30 of the hydrocarbon stream from the pressurized liquid hydrocarbon stream 15 and the energy needed to cooling and liquefying the steam recycling stream 115 in the hydrocarbon stream heat exchanger 30.

The cooling operation of the pressurized liquid hydrocarbon stream 15 depends on the change in temperature of the stream, that is, the extent to which it is heated in the hydrocarbon stream heat exchanger 30, as well as the specific heat capacity of the current.

Taking a stream of liquefied natural gas as an example of a stream of pressurized liquefied hydrocarbon, the specific heat capacity increases as the pressure of the stream decreases. As the specific heat capacity increases, the cooling capacity of the liquefied natural gas stream will also increase. For example, the cooling capacity of liquefied natural gas at 10 bar is approximately 1.75% more than the cooling capacity at 75 bar. This provides a significant effect in terms of the cooling operation of this current. Thus, for this reason lower cold recovery pressures are preferred.

The change in temperature of the pressurized liquid hydrocarbon stream 15 of the heat exchanger will depend on the temperature of the heated liquid hydrocarbon stream 35. This temperature is related to the working pressure of the heat exchanger 30. Thus, the higher the temperature at which the pressurized liquid hydrocarbon stream 15 is heated in the hydrocarbon stream heat exchanger 30, the higher the Cold recovery pressure is required. However, as mentioned above, the higher the pressure, the lower the specific heat capacity of the pressurized liquid hydrocarbon stream 15, and thus the lower the cooling capacity. Therefore, the choice of cold recovery pressure is a balance between the specific heat capacity of the liquid hydrocarbon and the temperature rise of the liquid hydrocarbon in the heat exchanger 30.

Another limitation of the cooling operation provided by the pressurized liquefied hydrocarbon stream 15 is that this stream should remain in the liquid phase in order to allow efficient pressurization in the heated hydrocarbon stream pump 40.

The energy required to cool and liquefy the steam recycle stream 115 is a function of the specific heat capacity of the steam recycle stream, the reduction of the temperature of the stream in the hydrocarbon stream heat exchanger 30, the enthalpy of liquefying the steam recycling stream at the discharge pressure of the recycling turbine 110 and the energy of any subcooling.

Thus, it is possible to determine the maximum proportion of one or more hydrocarbon gas streams 55 that can be expanded and liquefied, allowing recycling upstream of the hydrocarbon stream heat exchanger 30.

Within the border represented by the maximum part of one or more 55 gaseous hydrocarbon streams that can be reflicted in a final way, there are a number of factors that can be considered with a view to maximizing energy generation.

The extent to which one or more hydrocarbon gas streams 55 can be expanded through the recycling turbine 110 and re-located in the hydrocarbon stream heat exchanger 30 depends on the degree of expansion that is carried out in the turbine of Recycling 110. The greater the expansion, the lower the pressure of the steam recycling stream 115 that passes to the hydrocarbon stream heat exchanger 30. The lower the pressure of the steam recycling stream 115, the lower the temperature at which the hydrocarbon stream heat exchanger 30 will be liquefied.

However, the capacity of the liquid hydrocarbon stream 15 to liquefy the steam recycling stream 115 depends primarily on the pressure difference.

A ratio of the cold recovery pressure to the pressure of the steam recycling stream 115 within the range of 2 to 3 is advantageous, since it provides a net cooling curve for the steam recycling stream 115.

For example, when the liquid hydrocarbon is LNG, the cold recovery pressure is 20 bar, and the pressure of the steam recycling stream 115 is 7 bar, the separation ratio, that is, the extent to which The liquid hydrocarbon can be recycled after vaporization can be approximately 27%, that is, 27% by weight of one or more of the gaseous streams of hydrocarbons can be passed to the recycling turbine 110 for production of energy and subsequently it can be relieved in the hydrocarbon stream heat exchanger 30 and can be returned upstream of the heat exchanger. In this case, approximately one third of the flow can be expanded.

However, it should be appreciated that it may happen that the method disclosed herein does not have an individual optimum point. There is an interval for the expansion of the first recycled part 55a of one or more hydrocarbon gas streams between 5 and 45 bar, with a separation ratio for the part of the recycled stream 55a of between 15% (at 5 bar) and 65% (at 45 bar). The optimization will depend on the composition of the liquid hydrocarbon stream, its temperature, as well as other factors such as the temperature approach inside the heat exchanger of the hydrocarbon stream between the liquid hydrocarbon stream and the recycle stream of steam.

Thus, for example, a regasification plant with a design of 5 million metric tons per year (MTPA) (that is, the production of the second part 55b of one or more streams 55 gaseous hydrocarbons), would be more profitable provide a steam recycling stream 115 that has expanded in a low pressure range and provided with a small flow rate, to the recycle stream, in order to minimize the size of the hydrocarbon stream heat exchanger 30 and the recycling turbine 110, with corresponding CAPEX savings.

Figure 2a shows additional embodiments of the method and apparatus disclosed herein. In one of said embodiments, the liquid hydrocarbon stream 5 is provided from a tank of

storage 400, by pumping a liquid hydrocarbon feed stream 405 with a feed pump 410, such as a submerged pump. Preferably, the feed pump 410 is an electric pump. Feed pump 410 provides a stream 415 of pumped liquid hydrocarbons, which can be passed through a feed valve 420, to provide a liquid stream of hydrocarbons at a feed pressure.

Normally, the liquid hydrocarbon is stored in a tank 400 under cryogenic conditions. For example, when the liquid hydrocarbon is liquefied natural gas, it can be stored at temperatures of less than -150 ° C in a thermally insulated tank. During storage under such cryogenic conditions, the liquid hydrocarbon may be at atmospheric pressure or at a pressure close to it, such as about 1 bar.

Temperature variations during storage can result in the vaporization of part of the liquefied hydrocarbon in the form of hydrocarbon gas vapor, also called evaporation gas. Said hydrocarbon gas vapor can be extracted from the top of the storage tank 400 or from an area near it, in the form of a stream 455 of evaporation gas and can be passed to the suction side of a compressor 460 of evaporation gas. The evaporation gas compressor 460 can be mechanically operated by means of an evaporation gas compressor actuator 470, such as an electric actuator powered by electricity generated by means of the electric generator 120 of recycle current.

The evaporation gas compressor 460 compresses the stream 455 of evaporation gas to provide a stream 465 of compressed evaporation gas. The heat of compression can be subsequently removed from the stream 465 of compressed evaporation gas, and this can be condensed in an evaporator gas condenser 480. The evaporation gas condenser 480 provides a stream 485 of liquefied evaporation gas, which can be returned to the storage tank 400. The stream 465 of compressed evaporation gas can be condensed against a liquefied stream of hydrocarbons (not shown), for example a liquefied hydrocarbon stream extracted from tank 400.

With respect to the gasification formation shown in Figure 2a, this differs from that of Figure 1 in that an optional additional heater 70 is provided to heat the gas stream 55 of hydrocarbons against a heat source to provide a gas stream 55c of hydrocarbons (heated) before passing it to the gas separation device 60 of gaseous hydrocarbons. Preferably, the heat source has a temperature less than or equal to room temperature, such as an ambient air source or ambient water, such as a seawater stream or a hydrocarbon stream produced in the gasification process. The optional heater 70 is advantageous if the gas stream 55 of hydrocarbons is produced at a temperature too low for one part, 55e, which has to be passed to the gas consumption devices. For example, if the gas stream of hydrocarbons is provided at 0 ° C or below 0 ° C, additional heating may be required to prevent condensation of water vapor on the associated pipe.

A hydrocarbon gas stream separation device 60 provides a first portion 55d of the hydrocarbon gas stream (heated) 55c for dynamic expansion and power generation of the recycling turbine 110.

The embodiment of Figure 2a shows another optional aspect of the method and apparatus where a second part 55e of the gaseous stream of hydrocarbons (heated) is passed to the suction of a pipe turbine

80. Pipe turbine 80 dynamically expands the second part 55e of the hydrocarbon gas stream 55c (heated) to provide an expanded gas hydrocarbon stream 85. The useful work extracted from the second part 55e of the current 55c is used to mechanically drive an electric pipeline generator 82 by means of a shaft 81 to produce electrical energy.

If required, the expanded gas hydrocarbon stream 85 can be passed to an additional heater 87, where it can be heated to, for example, 10-15 ° C in order to compensate for any cooling resulting from the expansion in the turbine 80 of hydrocarbon stream. Additional heater 87 provides a stream 95 of gaseous hydrocarbon pipe that can be passed to the hydrocarbon gas consumption devices. The additional heater 87 may be provided with a heat source, such as an ambient heat source, which has a temperature less than or equal to room temperature. The heat source may be one or more of an ambient air source, an environmental water source such as a seawater stream, and a hydrocarbon stream produced in the gasification process.

The optional hydrocarbon stream turbine 80 is advantageous when the heated liquid hydrocarbon stream 35 is pumped to a pressure above the pipeline pressure by means of the heated hydrocarbon stream pump 40. In such a situation, the second part 55e of the hydrocarbon gas stream 55c (heated) would be provided at a pressure above the pipeline pressure, and thus would require a pressure reduction before being passed into the gas network . In this way, the pressure reduction of the second part 55e of the current 55c can be used to generate additional energy. The heated liquid hydrocarbon stream 35 can be pumped to a pressure above the pipe pressure in order to provide a particular suction pressure for the recycle turbine 110, which is fed with the first part 55c of the gas stream 55c of hydrocarbons (heated).

Figure 2b provides alternative embodiments of the method and apparatus 1 disclosed herein in which additional heaters 90, 140 are provided to heat the first and second portions 55a, 55b of the hydrocarbon gas stream 55. Preferably, additional heaters 90, 140 are provided with heat sources having a temperature less than or equal to room temperature.

In contrast to the embodiment of Figure 2a, in which an additional individual heater 70 is provided to heat the hydrocarbon gas stream 55 upstream of the hydrocarbon gas separation device 60, additional heaters 90, 140 are provided in each one of the currents of part 55a, 55b so that the temperature of each current can be adjusted individually. It will be apparent to the skilled person that, as required, only one or more of these optional heaters 90, 140 may be present.

Thus, the first part 55a of the hydrocarbon gas stream 55 can be heated by means of the additional heater 140 which preferably has a heat source having a temperature less than or equal to the ambient temperature, to provide a first part 55f ( heated) of a gas stream 55 of hydrocarbons to the recycling turbine 110. This can be advantageous in controlling the suction temperature of the stream that is intended to expand in the recycling turbine 110 in order to maintain an efficient operation.

Similarly, the second part 55b of the hydrocarbon gas stream 55 can be heated in an optional heater 90 to provide a stream 55a of gas hydrocarbon pipe. The optional additional heater 90 is advantageous if the second part 55b of the hydrocarbon gas stream 55 is too cold to be passed to the gas network, and it must be heated before distribution.

In another optional embodiment shown in Figure 2b, the liquefied recycle stream 125, produced by liquefying the steam recycle stream 115 versus the pressurized liquid hydrocarbon stream 15, is passed directly to the liquid stream 5 hydrocarbons through a hydrocarbon stream mixing device 20a to provide a liquid hydrocarbon stream 5a (combined). This formation can be used when the recycle turbine 110 provides an expanded gas hydrocarbon stream 115 (steam recycle stream) at the feed pressure of the liquid hydrocarbon stream 5.

In this case, there is no requirement for a recycle stream pump to pressurize the liquefied recycle stream 125 to the cold recovery pressure, so that it can be combined with the stream 15 of pressurized liquefied hydrocarbons.

Although the energy requirements of the liquid hydrocarbon pump 10 would have to be increased to handle the liquefied (combined) hydrocarbon stream 5a, which comprises both the liquefied hydrocarbon stream 5 and the liquefied recycling stream 125, savings of CAPEX because no recycle current pump is required.

Figure 2c provides an alternative embodiment of the method and apparatus 1 disclosed herein in which, instead of a part, the entire gas stream of hydrocarbons is passed to the recycle turbine 110a for power generation.

In said embodiment, the recycling turbine 110 may be a multi-stage turbine. Said multistage recycling turbine 110 can provide two discharge streams, a first stream 115a of expanded gaseous hydrocarbons and a second stream 115b of expanded gaseous hydrocarbons. The first expanded recycle stream 115a may be an intermediate pressure stream that can be used to provide the gaseous hydrocarbon to be exported. In order to avoid subsequent repressurization of the first expanded recycle stream 115a, it should be provided at a pressure equal to or above, preferably equal, the pipe pressure. The second stream 115b of expanded gaseous hydrocarbons can be an intermediate pressure stream that can be used as a steam recycling stream.

If the first expanded gas hydrocarbon stream 115a is at the pipe pressure, an additional pressure reduction is not required. The first stream 115a of expanded gaseous hydrocarbons can be passed to an additional heater 87b, where it can be heated, for example, to 10-15 ° C, in order to raise the gas temperature to an appropriate temperature for export. The additional heater 87b may be provided with a heat source having a temperature less than or equal to the ambient temperature. Additional heater 87b provides a stream 95b of gaseous hydrocarbon pipe that can be passed to the hydrocarbon gas consumption devices. If the first expanded gas hydrocarbon stream 115a is at a pressure above the pipe pressure, it can be further expanded in a hydrocarbon stream turbine (not shown) in order to generate additional energy and reduce the pressure of this stream up to the pipe pressure for export. This embodiment is less preferred because, in this way, two turbines are required.

More preferred is the use of an individual turbine which would be a multi-stage recycling turbine 110a, which would provide the first expanded gas hydrocarbon stream 115a at the pipeline pressure, as well as the second expanded gas hydrocarbon stream 115b which has to be used. as steam recycling stream. The use of an individual turbine in the formation shown in Figure 2c provides CAPEX savings.

The second expanded gaseous hydrocarbon stream 115b can be passed to the hydrocarbon stream heat exchanger 30 for the liquefied versus the liquid hydrocarbon stream 15, as described in the embodiment of Figure 1.

Figure 3 shows a further embodiment of the method and apparatus 1 disclosed herein, where multiple steam recycling streams 115, operating at different pressures, are liquefied in the hydrocarbon stream heat exchanger 30. The provision of two or more steam recycling streams 115 at different pressures is advantageous because it allows an improved thermal transfer in the heat exchanger 30. In particular, the cooling curves of multiple steam recycling streams 115 can be used. to provide a better adaptation of the heating curve of the pressurized (combined) liquid hydrocarbon stream 15a.

In an example of this formation, the liquid hydrocarbon stream 5 can be a stream of liquefied natural gas, provided at a feed pressure of, for example, 1 bar, and pressurized to a cold recovery pressure of, for example, 30 bar by means of a pump 10 of natural gas liquid stream. Subsequently, the pressurized LNG stream 15 is combined with a liquefied recycle stream 125 at a mixing temperature of, for example, -146 ° C by means of a natural gas stream mixing device 20 to provide the LNG stream 15a pressurized (combined) with a mass flow of, for example, 50 kg / s. The pressurized (combined) LNG stream 15a is passed to the natural gas stream heat exchanger 30, which can be a condenser.

The condenser 30 heats the pressurized (combined) LNG stream 15a to provide a heated LNG stream 35 at a temperature of, for example, -95 ° C. The heated LNG stream 35 is passed to a heated LNG pump 40, where it is pressurized to a pressure of, for example, 75 bar to provide a pressurized heated LNG stream 45. The pressurized heated LNG stream 45 can be vaporized in a LNG stream device 50 with a heat source, for example up to a temperature within the range of 10-15 ° C to provide a gas stream 55 of natural gas. Preferably, the heat source has a temperature less than or equal to room temperature, and is more preferably an ambient heat source. For example, preferably the LNG current heater 50 is an open grid vaporizer.

The gas stream 55 of natural gas can have a mass flow of, for example, 50 kg / s, and is passed to a device 60 for separating the gas stream of natural gas. The 55 gas stream of natural gas is divided into two parts. A first part, 55a, is passed to a recycling turbine 110, for example at a mass flow of 19 kg / s. A second part 55b can be passed to a gas network. The second stream will be at the pipe pressure of 75 bar, if the pressurized heated LNG stream 45 is pumped up to this pressure.

The first part 55a of the gas stream 55 of natural gas is dynamically expanded in the recycling turbine 110 from the pipe pressure, for example 75 bar. The recycling turbine 110b may be a multi-stage recycling turbine. Said multi-stage recycling turbine 110b can provide two discharge streams, a first stream 115c of expanded natural gas, for example with a pressure of 25 bar and a mass flow of 7 kg / s, and a second stream 115d of natural gas expanded soda, for example with a pressure of 10 bar and a mass flow of 12 kg / s. Subsequently, both the first and second streams 115a, 115b of gaseous natural gas expanded to a condenser 30 for liquefaction can be passed in front of the liquid LNG stream 15.

The first stream 115c of expanded gaseous natural gas can be liquefied in the condenser 30, for example at 115 ° C, to provide a first stream 125c liquefied for recycling. The second stream 115d of expanded gaseous natural gas can be liquefied in a condenser 30, for example at -130 ° C, to provide a second stream liquefied 125d of recycle gas. The first stream 115c of expanded gaseous natural gas will liquefy more easily in the condenser 30 than the second stream 115d, because the first stream is at a higher pressure. Therefore, the first expanded current 115c will have a better heat transfer of heat exchanger temperature and will avoid a minimum internal temperature approach too low for exchanger 30.

The first and second streams 125c, 125d liquefied from recycling can be passed to a pump 130 of multistage recycling stream in which they are pressurized, for example up to 31 bar, to provide a stream 135 of pressurized liquefied recycling, for example with a mass flow of 19 kg / s. Subsequently, the pressurized liquefied recycle stream 135 can be mixed with the pressurized LNG stream 15 by means of a natural gas stream mixing device 20.

The pressurized LNG stream 15 is provided by the LNG stream 5, which can be extracted from an LNG source such as a storage tank. When the LNG stream 5 has a mass flow of 31 kg / s, the pressurized LNG stream 15 will have a similar mass flow. Thus, the pressurized (combined) LNG stream 15a, comprising the pressurized LNG stream 15 and the pressurized liquefied recycle stream 135 will have the required mass flow of 50 kg / s. Accordingly, this embodiment provides a formation in which 38% by mass (i.e. 19/50 kg / s) of natural gas is recycled to the condenser 30.

The multi-stage recycling turbine 110 can produce 2.5 MW / MTPA of energy when used with the exemplary mass flows, pressures and temperatures provided in the present embodiment. The energy consumption of pumps 10, 40 and 130 is 0.4 MW / MTPA in total, so that a net energy production of 2.1 MW / MTPA is provided. This is above the energy threshold necessary to provide an autonomous gasification terminal and, thus, would not require any external energy, or the use of any fuel to generate additional energy during steady-state operation.

In an alternative embodiment not shown in Figure 3, one or both multi-stage recycling turbines 110 can be replaced and the multi-stage recycling current pump 130 can be replaced by two or more recycling turbines 110b and two or more pumps recycling stream respectively.

Figure 4 provides another embodiment of the method and apparatus 1 disclosed herein. In this formation, a Rankine cycle is incorporated into the regasification process in accordance with the embodiment of Figure 1 to increase the energy generated. It will be apparent that said Rankine cycle can be used with any embodiment disclosed herein.

One or more Rankine 200 circuits may be added to generate additional energy from a stream of pressurized heated liquid hydrocarbons. The pressurized heated liquid hydrocarbon stream 45 is provided by the heated hydrocarbon stream pump 40, in which it has been pressurized to a minimum or higher pipe pressure. In a preferred embodiment, the pressurized heated liquid hydrocarbon stream is heated to a supercritical pressure, for example within the range of 65 to 85 bar.

Prior to the vaporization in one or more LNG current heaters 50, the pressurized heated liquid hydrocarbon stream 45 can be passed to a working fluid heat exchanger 210, where it is heated against a stream of working fluid 245 vaporized expanded in the Rankine 200 circuit, to provide a stream 45a of heated (additional) liquid hydrocarbon and a stream 215 liquefied of working fluid.

Preferably, the working fluid has a condensation temperature between -20 and -50 ° C. In some cases, a refrigerant is useful as a working fluid. Preferred working fluids are selected from one or more of the group comprising: tetrafluoromethane (R14), ethane, pentafluoroethane (R125) and propane.

The cold energy from the stream 45 of pressurized heated liquid hydrocarbons is used to liquefy the working fluid in the stream 245 of expanded vaporized working fluid. The liquified stream 215 of working fluid produced in this way can be subsequently passed to a working fluid pump 220, in which it is pressurized to provide a stream 225 of pressurized liquefied working fluid. Preferably, the liquid stream 215 of working fluid is pumped to a pressure within the range of 5 to 12 bar, more preferably about 6.2 bar. Generally, it is preferred to pump the liquid stream 215 of working fluid to its dew point pressure at room temperature. Subsequently, said liquid stream of working fluid can be vaporized against a heat source at 15 ° C.

Then, the stream 225 of pressurized liquefied working fluid can be passed to a working fluid heater 230, where it is vaporized in front of a heat source. Preferably, the heat source has a temperature less than or equal to room temperature, such as a stream 325 of ambient air or ambient water supply. In an alternative embodiment, the heat source may be a hydrocarbon stream generated as part of the gasification method. Preferably, the working fluid heater 320 is an open grid vaporizer. The working fluid heater 230 provides a stream 235 of vaporized working fluid, and a cooled heat source, such as water, air or a hydrocarbon stream 345a, which is a cooled stream.

Subsequently, the vaporized stream of working fluid 235 can be passed to a working fluid turbine 240, where it is dynamically expanded to provide power and the stream 245 of expanded vaporized working fluid. Energy is produced by mechanical actuation of an electric working fluid generator 250 with the working fluid turbine 240 by means of the axis 242. Preferably, the vaporized stream 23 of working fluid is expanded to a pressure within the range of 1 to 3 bar, more preferably about 1.2 bar.

Ideally, expansion to a minimum pressure in the working fluid turbine would be preferred in order to

Maximize power generation. However, the lower the pressure of the stream 245 of expanded vaporized working fluid, the more difficult it will be to liquefy. On the contrary, the higher the pressure of the stream 245 of expanded vaporized working fluid, the easier it will be to liquefy, so that although less energy is generated in the working fluid turbine 240, a heat exchanger 210 of Working fluid heat smaller and less expensive.

Subsequently, the heated (additional) liquid hydrocarbon stream 45a may be vaporized against a heat source 345a to provide a cooled heat source, such as a stream 355a of water or cooled air, and a gas stream 355 of hydrocarbons. Preferably, the heat source 345a has a temperature less than or equal to room temperature, and can be a stream 345a of hydrocarbons, air or water produced by means of the working fluid heater 230.

Said embodiment is capable of producing 4 MW / MTPA energy. Approximately 2 MW / MTPA can be generated from the recycle turbine 110 and the electric generator 120 of recycle current, similar to the embodiment of Figure 1. Another 2 MW / MTPA can be generated from the turbine 240 of working fluid and electric generator 250 of working fluid. A power generation of 4 MW / MTPA is equivalent to the emission of 12200 tons / year of carbon dioxide produced by generating electricity from the combustion of natural gas in a combined cycle power generation apparatus. This elimination of carbon dioxide emissions represents a significant advantage, with the additional benefit that the additional electricity generated that is not used in the steady-state operation of the gasification facility can be exported to other facilities or to an external electricity grid. .

The person skilled in the art will understand that the present invention can be carried out in several ways without departing from the scope of the appended claims. For example, the energy generated from the embodiment of Figure 4 incorporating a Rankine circuit could be increased through the use of two or more streams 115 of expanded gaseous hydrocarbons at different pressure levels, as described in relation to the embodiment of Figure 3.

Claims (16)

1. A method for the gasification of a liquid stream (5) of hydrocarbons to provide a stream (55) of hydrocarbons and energy gas, comprising at least the steps of:

(to)

 pressurize a liquid stream (5) of hydrocarbons at a feed pressure to provide a stream (15) of pressurized liquid hydrocarbons at a cold recovery pressure;

(b)

 subjecting the stream (15) of pressurized liquid hydrocarbons to heat exchange against one or more steam recycling streams (115) to provide a stream (35) of heated liquid hydrocarbons and one or more liquefied recycling streams (125);

(C)

pass one or more liquefied recycling streams (125), after pressurization if necessary, to one or both of the liquid hydrocarbon stream (5) and the pressurized liquefied hydrocarbon stream (15);

(d)

 pressurize one or more parts of the heated liquid hydrocarbon stream (35) to provide one or more streams (45) of pressurized heated liquid hydrocarbons, at least one of which is at a minimum or higher pipeline pressure;

(and)

 vaporize one or more of the streams (45) of pressurized heated liquid hydrocarbons, at least one of which is at the minimum or highest pipe pressure, against one or more sources of heat

(345) to provide one or more hydrocarbon gas streams (55), at least one of which is at the minimum or highest pipe pressure; (f) dynamically expand at least a part (55, 55a, 55e) of at least one or more hydrocarbon gas streams (55) to provide energy and one or more streams (115) of expanded gas hydrocarbons, where at least a part of said one or more expanded gaseous hydrocarbon streams forms at least a part of one or more steam recycling streams (115).

2.

 The method according to claim 1, wherein all stages of heat exchange and vaporization resulting in an increase in the temperature of any of the hydrocarbon streams (15, 45, 55) are carried out against one or both of a heat source having a temperature less than or substantially equal to room temperature and a hydrocarbon stream (115) generated in the gasification method.

3.

 The method according to claim 1 or 2, wherein between the steps (e) and (f), a gas stream (55) of hydrocarbons is divided into a first part (55a, 55d) of the gas stream (55) of hydrocarbons and a second part (55b, 55e) of the hydrocarbon gas stream (55), and where step (f) of the first part (55a, 55d) of the hydrocarbon gas stream (55) is dynamically expanded to provide one or more first streams of gaseous hydrocarbons expanded in the form of one or more steam recycling streams (115).

Four.

 The method according to claim 3, wherein in step (f) the dynamic expansion provides at least two first streams of gaseous hydrocarbons expanded in the form of two steam recycling streams (115), each of said streams at different pressures , in step (b) the heat exchanger provides two first streams (125) of liquefied hydrocarbons and in the pressurization stage (c) at least two first streams of liquefied recycling are pressurized to provide a stream (135) of pressurized liquefied recycling, which is passed to the stream (15) of pressurized liquid hydrocarbons.

5.

 The method according to claim 4, wherein the dynamic expansion of stage (f) is carried out in a multi-stage recycling turbine (110) and in stage (c) the pressurization is carried out in a pump ( 130) of multistage recycling stream.

6.

 The method according to any one of the preceding claims, further comprising the step of heating the hydrocarbon gas stream (55) against a heat source (70) between stages (e) and (f).

7.

 The method according to any one of claims 3 to 5 further comprising the steps of:

-

 heating the first part (55a) of the hydrocarbon gas stream (55) against a heat source before the dynamic expansion of stage (f); Y

-

 heating the second part (55b) of the hydrocarbon gas stream (55) against a heat source.

8. The method according to one of the preceding claims wherein step (c) comprises one or both of:

(i)

 pass at least one of one or more of the liquefied recycling streams (125) to the liquid hydrocarbon stream (5) if one or more of the liquefied recycling streams (125) are at the supply pressure or

(ii)

 pressurize at least one of one or more of the liquefied recycle streams (125) to provide a pressurized liquefied recycle stream (135) to the cold recovery pressure and pass the

pressurized liquefied recycling stream to the stream (15) of pressurized liquid hydrocarbons, if the pressure of one or more liquefied recycling streams (125) is above the supply pressure. 9. The method according to one of the preceding claims, wherein at least one (55c) of one or more hydrocarbon gas streams (55) is at a pressure greater than the minimum pipe pressure, the method further comprising the steps of :

(g)

 dynamically expand at least a part (55e) of at least one hydrocarbon gas stream (55c) that is at a pressure greater than the minimum pipe pressure in a pipe turbine (80), said pipe turbine mechanically driving a generator ( 82) electrical pipe to provide electrical power and an expanded gas hydrocarbon stream (85) that is at a pressure of at least the minimum pipe pressure; Y

(h)

 heating the expanded gaseous hydrocarbon stream (85) against a heat source to provide a heated gaseous hydrocarbon stream (95);

(i)

 Pass the stream (95) of heated gaseous hydrocarbons to a gas network.

10. The method according to any of the preceding claims further comprising, between steps (d) and (e), the steps of:

-

 heat exchange at least one of one or more streams (45) of pressurized heated liquid hydrocarbons against a stream (245) of expanded vaporized working fluid to provide a stream (215) of liquefied working fluid;

-

 pressurize the stream (215) of liquefied working fluid to provide a stream (225) of pressurized liquefied working fluid;

-

 vaporize the stream (225) of pressurized liquefied working fluid against a heat source (325) to provide a stream (235) of vaporized working fluid; Y

-

 dynamically expand the stream (235) of vaporized working fluid in a working fluid turbine (240), said working fluid turbine (240) mechanically operating an electric working fluid generator (250), to provide electric power and the stream (245) of expanded vaporized working fluid.

eleven.

 The method according to any of the preceding claims wherein the cold recovery pressure is within the range of 10 to less than 60 bar, more preferably 20 to less than 50 bar and / or the minimum pipe pressure is greater than or equal to than 60 bar, more preferably greater than or equal to 70 bar, even more preferably greater than or equal to 75 bar.

12.

 The method according to any of the preceding claims, wherein said one or more heat sources

(345) have a temperature less than or equal to room temperature.

13.

 The method according to any of the preceding claims wherein the liquid hydrocarbon stream (5) is liquefied natural gas and one or more of the hydrocarbon gas streams (55) comprise a stream (55b) of natural gas.

14.

 An apparatus (1) for the gasification of a liquid stream (5) of hydrocarbons to provide a stream

(55) hydrocarbon gas, said apparatus comprising at least:

-

 a liquid hydrocarbon stream pump (10) for pressurizing a liquid hydrocarbon stream (5) at a feed pressure to provide a stream (15) of pressurized liquefied hydrocarbons at a cold recovery pressure;

-

 a hydrocarbon stream heat exchanger (30) to subject the pressurized liquid hydrocarbon stream (15) to heat exchange against one or more steam recycling streams (115) to provide a heated liquid hydrocarbon stream (35) and one or more streams (125) of liquefied recycling;

-

 a heated hydrocarbon pump (40) to pressurize one or more parts of the stream

(35) of heated liquid hydrocarbons to provide one or more streams (45) of pressurized heated liquid hydrocarbons, at least one of which is at a minimum or higher pipe pressure;

-

 a heat source (345) for vaporizing one or more of the streams (45) of pressurized heated liquid hydrocarbons, at least one of which is at a minimum or higher pipe pressure, to provide one or more hydrocarbon gas streams ;

-

 a recycling turbine (110) to dynamically expand at least a part (55, 55a, 55e) of at least one of one or more of the gaseous hydrocarbon streams (55) to drive an axis (112) and provide one or more streams of expanded gaseous hydrocarbons, at least a part of which forms at least a part of one or more steam recycling streams (115); Y

-

 one or more hydrocarbon stream mixing devices (20) for introducing one or more of the liquefied recycling streams (125), or a stream derived therefrom (135), into the stream (5)

liquid hydrocarbon or stream (15) of pressurized liquefied hydrocarbons. 15. The apparatus (1) according to claim 14, further comprising: 5 - a recycle stream pump (130) to pressurize one or more of the liquefied recycle streams (125) to provide a pressurized liquefied recycle stream (135) to the cold recovery pressure; Y where the hydrocarbon stream mixing device (20) introduces the pressurized liquefied recycle stream (135) into the pressurized liquid hydrocarbon stream (15). 16. The apparatus (1) according to claim 14 or 15, wherein the heat source (345) has a temperature less than or substantially equal to the ambient temperature.