KR20220047785A - Methods for recovering refrigeration energy through liquefaction or power generation of gas streams - Google Patents

Abstract

The present invention relates to a method for recovering refrigeration energy from a cold stream (F) in a system, the system comprising: a storage tank (203), at least one generator (G), and to flow a fluid such that it is arranged in heat exchange relationship at least one heat exchange device comprising a plurality of passageways configured, the method comprising: in a first mode of operation, for at least one first hot stream (C1 ), a first working fluid in at least one first passageway vaporizing at least a portion of (W1); expanding a first working fluid (W1) originating from step a) of the first passageway (1) in a first expansion component cooperating with the first generator to produce electrical energy; condensing at least a portion of the expanded first working fluid (W1) against at least the first cold stream (F); increasing the pressure of the first working fluid (W1); and reintroducing the first working fluid W1 into the first passage. According to the present invention, the second mode of operation comprises the steps of introducing a feed stream (200); condensing at least a portion of the feed stream (200) against a cold stream (F) to produce an at least partially liquefied feed stream (201); and filling the storage tank (203) with the at least partially liquefied feed stream (201).

Description

Methods for recovering refrigeration energy through liquefaction or power generation of gas streams

The present invention relates to a process for recovering refrigeration energy from a cold stream for generating electrical energy from at least one Rankine cycle or for liquefying a feed stream. If the cryogenic stream is a cryogenic liquid stream, such as liquefied natural gas, the stream can be regasified for distribution to a distribution network while upgrading its refrigeration content.

Natural gas from fields remote from the point of consumption is typically liquefied before being stored on board specially tailored vessels, methane tankers, for transport over long distances. The reason is that natural gas in liquid form occupies a smaller volume for a given mass and does not need to be stored at high pressure.

Before being fed to the distribution network, the liquefied natural gas (LNG) has to be regasified (or ie reevaporated) to a pressure of about 10 to 90 bar, depending on the grid. This flash-evaporation is carried out at the LNG terminal, usually at ambient temperature, by exchanging heat with seawater (possibly seawater heated with natural gas). In this case, the refrigeration output of liquefied natural gas is not upgraded at all.

Various methods exist for generating electricity from a frigori of liquefied natural gas and upgrading its energy output.

One known method is based on the direct expansion of natural gas. Liquefied natural gas is pumped to a pressure exceeding the pressure of the distribution network, vaporized by heat exchange with a hot source such as seawater, and then expanded to grid pressure in an expansion turbine associated with a generator.

Another method is based on a thermodynamic cycle using an intermediate fluid or a working fluid. Among these methods is the Rankine cycle, in which a working fluid is vaporized under pressure against a hot source such as seawater in a first heat exchanger and then expanded in a turbine connected to a generator. The expanded working fluid is then condensed in a second exchanger with respect to the LNG used as the cold source of the cycle. This results in a low pressure liquid working fluid, which is pumped back into the first exchanger at high pressure, thereby terminating the cycle.

Such Rankine cycles are disclosed inter alia in CN-A-105545390, US-A-2016109180, CN-A-105865149 and EP-A-2278210.

The Rankine cycle can function using water as the working fluid for applications such as geothermal heat recovery, but by using an organic fluid that evaporates at a lower temperature, a cold source can be used at a lower temperature. In this case, it is referred to as the organic Rankine cycle (ORC).

Typically, ORC cycles are industrialized using LNG as a cold source and seawater as a hot source. This cycle enables regasification of the LNG stream while generating electricity with an energy output of about 20 kWh per tonne of vaporized LNG (ie 0.015 kWh/Nm ³ ).

In addition, demand for electricity is not constant, and electricity production methods must exhibit increasing flexibility. This is explained in particular by the difficulty of storing electricity. Therefore, in order to prevent the generation of tension on the electric grid, which is reflected by large fluctuations in electricity prices, it is necessary to constantly balance the supply and demand.

SUMMARY OF THE INVENTION It is an object of the present invention to solve, in whole or in part, the above-mentioned problems, in particular by proposing a refrigeration energy recovery process which provides increased flexibility to be able to adapt to fluctuations in electricity demand.

Accordingly, a solution according to the present invention is a process for recovering refrigeration energy from a cold stream in a system, the system comprising a storage tank, at least one generator, and a plurality of channels configured to flow a fluid into a heat exchange relationship. at least one heat exchange device, the process comprising: in a first mode of operation,

a) introducing a first working fluid having a first high pressure into at least one first channel and for at least one first hot stream flowing in at least one second channel in heat exchange relationship with said at least one first channel vaporizing at least a portion of the first working fluid;

b) delivering the first working fluid obtained in step a) from the first channel to expand it to a first low pressure lower than the first high pressure in a first expandable member cooperating with the first generator to generate electrical energy; ;

c) introducing the expanded first working fluid in step b) into the at least one third channel, the at least one fourth channel being in heat exchange relationship with the at least one third channel for at least a cold flow of the first working fluid condensing at least a portion;

d) transferring the first working fluid at least partially condensed in step c) from the third channel, raising the pressure of the first working fluid to the first pressure and re-introducing it into the first channel; The process, in a second mode of operation,

e) introducing a feed stream into at least one tenth channel in heat exchange relationship with the at least fourth channel;

f) at the outlet of the tenth channel, condensing at least a portion of the feed stream against a cold stream to produce an at least partially liquefied feed stream; and

g) filling the storage tank with the feed stream produced in step f). Optionally, the present invention may include one or more of the following features:

- The process is

h) introducing the feed stream obtained from step f) into a supercooler;

i) passing a feed stream from a supercooler to expand in a third expandable member to form a gas phase and a liquid phase of the feed stream;

j) introducing the gaseous phase and the liquid phase into a storage tank;

k) extracting at least a portion of the gas phase from the storage tank and introducing it into the subcooler to cool the feed stream flowing in the subcooler by heat exchange with the gas phase;

l) compressing the gas phase in a compression device to form a compressed gas phase and introducing the compressed gas phase into the feed stream prior to introduction into the tenth channel;

- the cold stream exiting the fourth channel enters at least one eighth channel, the process comprising: in a first mode of operation;

m) introducing a second working fluid having a second high pressure into at least one fifth channel, said second for at least one second hot stream flowing in at least one sixth channel in heat exchange relationship with at least the fifth channel vaporizing at least a portion of the working fluid;

n) delivering a second working fluid at least partially vaporized in step m) from the fifth channel, expanding it to a second low pressure in a second expandable member cooperating with a second generator to produce electrical energy, Lp2 is lower than Hp2, step;

o) introducing the second working fluid expanded in step n) into at least one seventh channel in heat exchange relationship with at least the eighth channel and condensing at least a portion of the second working fluid against a cold stream flowing in the eighth channel making;

p) delivering the at least partially condensed second working fluid in step g) from the seventh channel to raise the pressure of the second working fluid to a second high pressure, and wherein the second at least partially condensed second working fluid in step g) the further step of re-introducing the working fluid into the fifth channel;

The process comprises, in a second mode of operation,

q) before step f), introducing a feed stream into at least one eleventh channel in heat exchange relationship with the eighth channel;

r) cooling the feed stream against a cold stream and introducing the cooled feed stream into the tenth channel to obtain a cooled feed stream at the outlet of the eleventh channel, with at least some possible condensation an additional step of the step;

- the cold stream exiting the fourth channel enters at least one eighth channel, the process comprising: in a first mode of operation,

s) introducing a second working fluid having a second high pressure into the at least one fifth channel and against at least one second hot stream flowing in the at least one sixth channel 6 in heat exchange relationship with the at least fifth channel vaporizing at least a portion of the second working fluid;

t) delivering a second working fluid at least partially vaporized in step s) from the fifth channel, expanding it to a second low pressure in a second expandable member cooperating with a second generator to produce electrical energy, Lp2 is lower than Hp2, step;

u) introducing a second working fluid expanded in step t) into a second channel and condensing at least a portion of the second working fluid against at least a cold stream flowing in the eighth channel;

v) conveying from a second channel the at least partially condensed second working fluid in step u) to raise the pressure of the second working fluid to a second high pressure, wherein the second at least partially condensed second working fluid in step u) the further step of re-introducing the working fluid into the fifth channel;

the first hot stream flowing in step a) is formed at least in part by the second working fluid flowing in step u) in the channel,

The process comprises, in a second mode of operation,

w) before step f), introducing a feed stream into at least one eleventh channel in heat exchange relationship with the at least eighth channel;

x) cooling the feed stream against a cold stream to obtain a cooled feed stream at the outlet of the eleventh channel, with at least some possible condensation, and introducing the cooled feed stream into the tenth channel. an additional step of the step;

- the first working fluid and the second working fluid are organic fluids, the first working fluid and the second working fluid comprising a first hydrocarbon mixture and a second hydrocarbon mixture respectively, the first and second hydrocarbon mixtures preferably is, optionally with addition of at least one additional component selected from nitrogen, argon, helium, carbon dioxide, and neon, at least two hydrocarbons selected from methane, ethane, propane, butane, ethylene, propylene, butene, and isobutane Each includes

- the first working fluid and the second working fluid are organic fluids, the first working fluid and the second working fluid are pure substances consisting of the first hydrocarbon and the second hydrocarbon, respectively;

- the feed stream is formed mostly, preferably completely or almost completely, of an air gas, preferably nitrogen, oxygen or argon,

- the cryogenic stream is a stream of liquefied hydrocarbons, such as liquefied natural gas, or a stream of a cryogenic liquid selected from a stream of liquid nitrogen, a stream of liquid oxygen, a stream of liquid hydrogen;

- the first hot stream, the second hot stream, and/or the third stream are formed of seawater, preferably seawater that is introduced at a temperature exactly above 0°C, preferably between 10°C and 30°C, the seawater optionally through a pre-heating step,

- the process is optionally carried out according to the first mode of operation or the second mode of operation,

- the selection of the first or second mode of operation is made according to the value of at least one parameter representing the quantity of electricity demanded, preferably, the process comprises: electrical energy consumed via the electricity supply network and/or by industrial installations and and/or at least one step of determining at least one value of the instantaneous power, wherein the process is performed in a first mode of operation if the value is above a predetermined threshold value, or in a second mode of operation if the value is below a predetermined threshold value. It is performed in 2 operating modes,

- in the second mode of operation, the flow rate of at least one of the first hot flow, the second hot flow, the first working fluid, and/or the second working fluid is reduced or stopped;

- the process is carried out simultaneously in a first mode of operation and in a second mode of operation so as to simultaneously produce electrical energy and an at least partially liquefied feed flow, said process comprising at least a first working fluid and/or a second working fluid (W2) comprising at least one step of adjusting the operation by a change in the flow rate,

- the feed stream obtained from step f) has a pressure of at least 5 bar, preferably at least 20 bar, more preferably at least 30 bar,

- the cold stream exiting the eighth channel enters into at least one ninth channel to be heated therein with respect to the second hot stream, the second working fluid, and/or the third hot stream, the feed stream comprising: before its introduction into the 11th channel into at least one thirteenth channel in heat exchange relationship with at least the ninth channel,

- the cold flow and the feed flow flow in counter-currentwise,

- the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth and/or thirteenth channel comprises at least one brazing plate ( forming part of a brazed plate heat exchanger, the exchanger comprising a stack of a plurality of parallel plates spaced apart to define a plurality of channels in a plurality of series therebetween;

- the feed stream is introduced in gaseous form into the tenth channel, the eleventh channel, and/or the thirteenth channel, preferably -200°C to -130°C, preferably -170°C to -130°C, more preferably Preferably, it is discharged in a completely condensed state from the tenth channel at a temperature of -160°C to -140°C.

According to another aspect, the present invention relates to a facility for recovering refrigeration energy from a cold stream in a system, the system comprising a storage tank, at least one generator, and a plurality of channels configured to flow a fluid into a heat exchange relationship. At least one heat exchange device comprising:

- at least one first channel configured to flow a first working fluid;

- at least one second channel configured to flow a first hot stream, wherein the second channel, in a first mode of operation, allows a first working fluid introduced into the first channel to flow at least partially with respect to the first hot stream at least one second channel in heat exchange relationship with the first channel to vaporize;

- a first expandable member disposed downstream of said first channel and configured to reduce a pressure of a first working fluid exiting said first channel from a first high pressure to a first low pressure;

- a generator connected to the first expandable member;

- at least one third channel arranged downstream of the first expandable member and configured to flow a first working fluid expanded by the first expandable member;

- at least one fourth channel configured to flow a cold stream, said fourth channel being at least partially relative to the cold stream in which, in a first mode of operation, a first working fluid introduced into the third channel is at least partially vaporized at least one fourth channel in heat exchange relationship with the third channel to be condensed into

- a first pressure-elevating member disposed downstream of said third channel and configured to increase a pressure of a first working fluid discharged from said third channel from a first low pressure to a first high pressure, said installation comprising: Is,

- at least one tenth channel configured to flow a feed stream, said channel heat exchange with the channel such that, in a second mode of operation, the feed stream introduced into the tenth channel is at least partially condensed with respect to the cold stream at least one tenth channel in a relationship; and

- further comprising a storage tank fluidly connected to the tenth channel.

Preferably, the equipment comprises:

- at least one fifth channel configured to flow a second working fluid;

- at least one sixth channel configured to flow a second hot stream, wherein in the first mode of operation, a second working fluid introduced into the fifth channel is at least partially with respect to the second hot stream at least one sixth channel in heat exchange relationship with the fifth channel for vaporization;

- a second expandable member disposed downstream of said first channel and configured to reduce a pressure of a second working fluid exiting said fifth channel from a second high pressure to a second low pressure;

- a second generator connected to the second expandable member;

- at least one second channel arranged downstream of the second expandable member and configured to flow a second working fluid expanded by the second expandable member;

- at least one eighth channel configured to flow a cold stream, said eighth channel being at least partially with respect to the cold stream in which, in a first mode of operation, a second working fluid introduced into the second channel is at least partially vaporized at least one eighth channel in heat exchange relationship with the second channel to be condensed into

- a second pressure-increasing member disposed downstream of said second channel and configured to increase a pressure of a second working fluid discharged from said second channel from a second low pressure to a second high pressure;

- at least one eleventh channel configured to flow a feed stream, said eleventh channel, in a second mode of operation, against the cold flow before the feed stream entering the tenth channel enters the tenth channel and at least one eleventh channel in heat exchange relationship with the eighth channel to be cooled and optionally at least partially condensed.

In addition, the present invention, the equipment according to the present invention; A system configured as a production unit, such as a cryogenic distillation air separation unit, suitable for generating a feed stream at at least one outlet of the production unit, wherein the at least one outlet is the facility is movably connected to

The term “natural gas” refers to any composition comprising hydrocarbons, including at least methane. This includes “raw” compositions (prior to any treatment or scrubbing) and includes, but is not limited to, sulfur, carbon dioxide, water, mercury, and certain heavy and aromatic hydrocarbons. Also included is any composition that has been partially, substantially, or completely treated for reduction and/or removal of any of the above compounds.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be better understood by the following description, which is given by way of example and not purely by way of limitation, and made with reference to the accompanying drawings, in which:
1 schematically shows a process for recovering refrigeration energy according to an embodiment of the present invention.
2 schematically shows a process for recovering refrigeration energy according to another embodiment of the present invention.
3 schematically shows a process for recovering refrigeration energy according to another embodiment of the present invention.
4 schematically shows a process for recovering refrigeration energy according to another embodiment of the present invention.
5 schematically shows a process for recovering refrigeration energy according to another embodiment of the present invention.
6 shows an exchange diagram obtained with a process according to an embodiment of the present invention.

The process according to the invention is carried out in particular by means of at least one heat exchange device, the at least one heat exchange device comprising channels suitable for flowing a plurality of fluids and enabling direct or indirect heat exchange between the fluids, It can be any device.

In the embodiments detailed below, the various fluids of the process flow in one or more brazed heat exchangers of plate and fin type, preferably made of aluminum. This exchanger improves the energy performance of the liquefaction process described above, since it allows to operate with small temperature differentials and with reduced pressure losses. In addition, the plate changer offers the advantage of achieving a very convenient device that provides a large exchange surface with a limited volume.

These exchangers contain stacks of plates that extend in two dimensions, length and width, thus constituting a stack of multiple series channels, some of which regulate the circulation of a thermogenic fluid (in this case, the working fluid of the cycle). and others are intended for circulation of a refrigerant fluid (in this case a cryogenic liquid such as liquefied natural gas to be vaporized).

Heat exchange structures, such as heat exchange waves or fins, are generally arranged in the channels of the exchanger. This structure includes fins extending between the exchanger plates to increase the heat exchange surface of the exchanger.

However, other types of exchangers may be used, such as plate exchangers, shell and tube exchangers, or plate exchangers or plate and fin exchangers built into the core of the kettle assembly, i.e. the shell in which the refrigerant fluid is vaporized. should be noted. If the exchanger is a tube exchanger, the channel may be defined by the space around and between the tubes.

1 schematically shows a process for recovering cold air from a low-temperature hydrocarbon stream (F). In particular, the cold stream F may be natural gas.

In this embodiment, a single Rankine cycle is performed by the first exchanger E1 and the second exchanger E2.

Preferably, the exchangers E1 and E2 each comprise a stack of a plurality of plates (not shown) arranged parallel to one another and spaced apart in a so-called stacking direction orthogonal to the plates. Thus, a plurality of channels are obtained for the process fluid to be brought into heat exchange relationship through the plate. A channel is formed between two adjacent plates. Preferably, the spacing between two successive plates is small compared to the length and width of each successive plate, so that each channel of the exchanger has a flat parallelepiped shape. Channels intended for circulation of the same fluid form a series of channels. Each exchanger includes a plurality of series of channels configured to flow various process fluids parallel to an overall flow direction z, one series of channels adjacent to some or all of the other series of channels and and/or alternately, wholly or partially.

The sealing of the channels along the edge of the plate is ensured by means of lateral and longitudinal sealing rods which are generally fixed on the plate. The lateral seal rod does not completely close the channel, but leaves inlet and outlet openings for the inlet and outlet of fluid. These inlet and outlet openings are joined by a generally semi-tubular shaped manifold to ensure uniform distribution and return of the fluid through all channels in the same series.

In the following text, reference will be made to one or at least one channel, it is understood that the channel may form part of a series of multiple channels for flowing the same fluid.

It is understood that these structural features are applicable in whole or in part to other exchanges described in this patent application.

The first exchanger E1 acts as a vaporizer in the Rankine cycle. As can be seen in FIG. 1 , the first working fluid W1 flows through the at least one first channel 1 from the inlet 1a to the outlet 1b . A first hot stream enters the first exchanger from the inlet 21 to the outlet 22 . The first working fluid W1 is at least partially vaporized by heat exchange with the first hot stream C1 .

The vaporized first working fluid W1, after being discharged from the first exchanger E1, is expanded in a first expansion member (preferably a turbine) connected to the generator G, wherein the generator G expands Converts the kinetic energy generated by the fluid into electrical energy.

The first working fluid W1, after its expansion, flows into the second heat exchanger E2 from the inlet 31 of the at least one third channel 3 to the outlet 32 .

The first working fluid W1 resulting from the expansion in the first member may possibly be in a two-phase state, and may be introduced through or without separation of liquid and gaseous phases upstream of the second exchanger E2. It should be noted that there is

The first working fluid W1 is brought into heat exchange relationship with the cold stream F flowing in the at least one fourth channel 4 of the second exchanger E2 from the inlet 41 to the outlet 42 . The first working fluid W1 is condensed by heating the cold stream F, and after pressurization by a pressure-increasing member such as a pump, is discharged in liquid form through the outlet 32 and subsequently into the first exchanger E1 By redistributing it in a negative way, it ends the Rankine cycle.

Preferably, the cold stream F, in liquid form, preferably completely liquid, enters through the inlet 41 of the second exchanger E2 and through the outlet 42 , at least partially and preferably It is discharged in a completely vaporized state.

The terms “hot flow” or “cold flow” refer to a flow formed by one or more fluids that provides a source of heat or cold air by heat exchange with another fluid.

According to the invention, the aforementioned Rankine cycle is carried out in a first mode of operation, wherein the process according to the invention ensures a recovery of the refrigeration output of the cold stream F for generating electricity.

Furthermore, according to the invention, the process has a second mode of operation, in which the refrigeration output of the cold stream F is recovered, not for generating electricity but for liquefying the feed stream.

In this second mode of operation, the feed stream 200 passes through at least one tenth channel 10 of the second exchanger E2 in heat exchange relationship with at least a fourth channel 4 through which the cold stream F flows. ) is introduced into At least a portion of the feed stream 200 is condensed with respect to the cold stream F, resulting in an at least partially liquefied, preferably fully liquefied, feed stream 201 at the outlet of the channel 10 . Preferably, the cold stream F is in a flow direction opposite to that of the feed stream 200 in the first mode of operation and/or in the second exchanger E2 condensed working fluid W1 in the second mode of operation. ) in the opposite flow direction. The cold stream F can be completely or partially vaporized in the channel 4 by heat exchange with respect to the working fluid W1 , ie with the working fluid W1 .

The feed stream 201 thus obtained is transferred to a storage tank 203 . Accordingly, the at least partially liquefied stream 201 can be stored at a storage pressure of preferably 1 to 10 bar, preferably 1 to 5 bar, and at a cryogenic temperature of approximately the equilibrium temperature of the fluid at the storage pressure. there is.

It is noted that the feed stream 201 can optionally be expanded in the third expandable member 202 to form a gaseous and liquid phase of the feed stream 201 . When storage in tank 203 is carried out at atmospheric pressure, or at least relatively low compared to the pressure of the liquefaction mesh, which may be up to 20 bar or even up to 40 bar, the at least partially liquefied feed stream 201 Such expansion is carried out. The reason is that liquefaction of the feed stream 200 is more efficient in the exchanger when operating at such high pressures.

The process of the present invention allows for the efficient recovery of the precycle of the cold stream F with increased flexibility (since the precycle can be used to generate electricity or to liquefy the feed stream), and the The choice is made according to the demand at the time. When the cold stream is a cryogenic liquid, especially natural gas, the process enables regasification of the cold stream while upgrading its refrigeration output. Switching from one operating mode to another is relatively simple and does not require any change of industrial equipment. In addition, liquefaction of the feed stream makes it possible to accumulate a stockpile of fluid in liquid form at reduced cost to ensure continuity of gas supply, for example in the event of a manufacturing plant shutdown.

It should be noted that FIG. 1 optionally shows a configuration in which the feed stream 201 obtained from the channel 10 flows through the subcooler 205 before being expanded and introduced into the storage tank 203 . The term "supercooler" refers to any heat exchange device configured to produce at its outlet a liquid at a temperature below its equilibrium temperature at an operating pressure.

The feed stream 201 at the outlet of the subcooler 205 expands in the third expandable member 202 to form a gaseous and liquid phase that flows together into the storage tank 203 (a “flash” phenomenon). ). The gas stream 204 resulting from the flash is withdrawn at the top of the storage tank 203 , preferably in the opposite flow direction, to further divert the feed stream 201 by heat exchange in the subcooler 205 . To cool, it flows into the supercooler 205 . This configuration provides the advantage of upgrading the pre-ring of gas stream 204 that is generally lost by being discharged from the reservoir. After exiting the subcooler 205 , the gas stream 204 is compressed to form a compressed gas stream 206 that can be recycled into the feed stream 200 before entering the tenth channel 10 . may be compressed on the device.

It is also conceivable for the at least partially liquefied feed stream 201 to be introduced directly into the tank 203 .

Preferably, the process according to the invention is operated alternately between the first and second modes of operation. The selection between the first and the second mode is made according to the determination of at least one parameter indicative of the amount of electricity demanded. The process may be performed in a first mode of operation if the parameter is above a predetermined threshold or may be performed in a second mode of operation if the parameter is below a predetermined threshold.

Preferably, in the second mode of operation, at least one heat exchange channel among the first hot stream C1 , the second hot stream C2 , the first working fluid W1 , and/or the second working fluid W2 . The flow through is stopped.

In particular, the process can be performed in advance via the electricity supply network or industrial installation, for example from direct measurements of the physical parameters of the installation (eg electricity supply voltage, intensity of the delivered current, etc.), or from the consumption history of the installation. at least one step of determining at least one value of instantaneous power and/or electrical energy that can be determined or measured. Similarly, in the case of an electric grid, the consumption can be determined immediately or from a data history, for example according to a time period or time of year.

The process is performed in a first operating mode if the value is above a predetermined threshold or in a second operating mode if the value is below a predetermined threshold. This makes it possible to deal with the consumption peaks of the plant and thus to reduce the tension on the electric grid.

Therefore, it is possible to more efficiently respond to the fluctuations in the energy demand, and at the same time to prevent overproduction in relation to the actual electricity consumption of users of the electricity supply chain, it is possible to continue upgrading the cold flow refrigeration energy by another use Do.

Alternatively or additionally, the process may include determining at least one other value of instantaneous power and/or electrical energy generated by the separate power generation device. The process is carried out in a first mode of operation when the value is below another predetermined threshold or in a second mode of operation when the value is above another predetermined threshold. Thus, by choosing to use a pre-ring of a cold stream to liquefy the feed stream, especially when excess energy is generated by the power generation device, intermittent, as is often the case, for example, in solar or wind power generation. It is possible to adjust with the development of phosphorus.

It is also conceivable to simultaneously operate the process in the first and second modes. In this case, a portion of the precycle of the cold stream is recovered to generate electrical energy and another portion of the precycle of the cold stream is used to liquefy the feed stream. The first and second modes are adjusted to produce more liquefied feed flow and less electrical energy when electricity demand decreases, and vice versa when electricity demand increases.

One mode of adjustment may be to vary the flow rate of at least the first working fluid W1 and/or the second working fluid W2 through their respective channels. By reducing the flow rate of the working fluid(s), less precycles must be withdrawn from the cold stream to condense the working fluid, thereby increasing the freecycles available for liquefying the feed stream 200 . Thus, more liquid feed flow and less electricity are generated. The opposite is caused by increasing the flow rate of the working fluid(s), thus continuing to produce a reduced amount of liquid flow while at the same time being desirable for power generation when so required by demand. Preferably, the process according to the invention acts to produce only electrical energy, or to produce both electrical energy and liquid feed flow of substantially reduced output. Thus, in order to carry out the second mode of operation, from 2% to 50%, preferably at least 5% and/or at most 20%, in the fluid flow rate for the first fluid W1 and/or the second fluid W2, More preferably it is possible to apply a reduction of 5% to 15%. Preferably, in a combined two cycle operation, the reduction in flow rate applied to the first fluid is greater than the reduction applied to the second fluid.

Preferably, the process according to the invention is capable of performing, in a first mode of operation, a combination of multiple Rankine cycles, in order to increase the energy yield of the process.

2 shows a combination of a first and a second Rankine cycle according to a first implementation variant. The process according to the invention, irrespective of whether it is a first variant or a second variant described below, for two rankine cycles, more than two rankine cycles combined according to the same principles as those described below It is understood that it may include cycles.

According to the description of the single cycle given above, the first Rankine cycle is performed by the first exchanger E1 and the second exchanger E2.

The second Rankine cycle preferably uses a second working fluid (W2) of a different composition than that of the first working fluid (W1). The second working fluid W2 flows into the third exchanger E3 through the inlet 51 through the outlet 52 and flows in at least one fifth channel 5, which has an inlet 61 and an outlet port ( 62) at least partially vaporized by heat exchange with the second hot stream C2 flowing in the at least one sixth channel 6 between them.

The second working fluid W2 expands according to the same principle as in the first cycle, possibly in a two-phase state and possibly with a phase separation prior to entry, the inlet 71 of the at least one seventh channel 7 . ) into the fourth heat exchanger E4 through the outlet 72 , which is condensed by heating the low-temperature stream F flowing in the at least one eighth channel 8 . The fourth exchanger E4 forms the condenser of the second cycle. The second working fluid W2 obtained from the outlet 72 in liquid form is pumped and re-introduced through the inlet 51 of the fifth channel 5, thereby terminating the second cycle.

It is noted that the cold stream F may be fully or partially vaporized and/or heated in the first Rankine cycle (channel 4 ) by heat exchange with the first fluid W1 . The cold stream F may be fully or partially vaporized in the second Rankine cycle (channel 8) by heat exchange with the second fluid W2.

According to one possibility, the cold stream F is heated only in the at least one fourth channel 4 and is vaporized only in the eighth channel 8 . The cold source of the first cycle is only the sensible heat of the de-subcooling of the cold stream.

According to another possibility, the cold stream is partially vaporized in the fourth channel 4 . The cold source of the first cycle is a portion of the latent heat of vaporization of the cold stream and the thermal sensation of the de-subcooling of the cold stream.

According to another possibility, the cold stream F is vaporized only in the at least one fourth channel 4 (ie it leaves the fourth channel 4 in a fully vaporized state). The cold source of the first cycle is all latent heat of vaporization of the cold stream and of the de-subcooling of the cold stream, possibly together with the thermal sensation of the heating of the vaporized cold stream.

Also, the cold stream F may be partially vaporized in the fourth channel 4 and partially vaporized in the eighth channel 8 .

In the context of the present invention, the first working fluid W1 discharged from the third channel 3 in a condensed state is reintroduced into the second exchanger E2 before being reintroduced into the first exchanger E1 and in it Note that it is possible to cycle. This configuration is preferred if the first working fluid W1 is not a pure substance, but a mixture of several constituents (which further increases the temperature at which the first working fluid W1 exits the second exchanger E2 ) Because it provides a boosting advantage). According to the same principle, the second working fluid W2 discharged from the channel 7 in a condensed state may be re-introduced into the fourth exchanger E4 before being re-introduced into the third exchanger E3. Figure 3 shows this type of configuration.

This principle of further passage to the condensate exchanger(s) is applicable to other embodiments described in this patent application (see, eg, FIG. 4 , channels 14 , 15 ).

Alternatively, it may be devised to introduce the first and second working fluids W1 , W2 directly into the first and third exchangers respectively, without further passage into the second and fourth exchangers.

In the first mode of operation, the cold stream F is continuously supplied to the first and second Rankine cycles, which are gradually vaporized and heated with respect to the second and first working fluids W2 and W1. Thus, F can possibly be thus in a two-phase state. The first Rankine cycle and the second Rankine cycle make it possible to generate electricity.

In the second mode of operation, the cold stream F is fed continuously to the second exchanger E2 and the fourth exchanger E4 , which are gradually vaporized and heated relative to the feed stream 200 . The feed stream 200 is continuously fed to a fourth exchanger E4 and a second exchanger E2, which are gradually cooled and condensed.

This arrangement ensures a more efficient recovery of cold air over the entire temperature gradient between the inlet temperature of the cold stream F of the fourth channel 4 and the temperature of the cold stream F of the outlet of the eighth channel 8 . while allowing the low-temperature stream to be regasified. Specifically, the recovery of the precycles from the cold stream is carried out separately through portions of the channels 4 and 8 having different temperature levels. It is then possible to optimally adjust the characteristics of the respective first and second working fluids so that they have high and low pressure levels selected for each of the two cycles and a boiling temperature suitable for these temperature levels. This provides a very wide degree of freedom for increasing the energy yield of the process by adjusting the temperature, pressure and/or composition of the working fluid, in particular according to the characteristics of the cold stream F to be heated (in particular its pressure, temperature, composition, etc.) provides

Preferably, the cold stream F exiting at 82 from the eighth channel 8 enters at least one ninth channel 9 of the fifth exchanger E5, whereby the third in the first mode of operation is Continue its heating to the hot stream C3 or to the feed stream 200 in the second mode of operation therein. This is desirable if the temperature achieved at the outlet 82 of the exchanger E4 is too low to be compatible with the material from which the pipes of the natural gas distribution network are formed. In this case, the feed stream enters the at least one thirteenth channel 13 upstream of its entry into the channel 11 , thereby cooling the feed stream 200 even more effectively in the second mode of operation. make it possible

Preferably, at a temperature between 0° C. and 30° C., feed stream 200 enters the process (ie the exchanger through which stream 200 first passes (depending on the configuration employed, E2, E5, E4, E3). may be)). Preferably, the feed stream 200 is introduced into the process entirely in gaseous form.

Preferably, the feed stream 200 is formed mostly, preferably completely or almost completely, of an air gas, preferably nitrogen, oxygen or argon.

The term "air gas" means a gas that forms part of the composition of air, such as argon, carbon dioxide, helium, nitrogen and oxygen.

In particular, the plant carrying out the process according to the invention is flowably connected to said plant (in particular the channels 10 , 11 and/or 13 depending on the embodiment contemplated), preferably via at least one pipe. It may be incorporated into a system comprising at least one device (eg an air separation unit (ASU)) for generating the feed stream, preferably by cryogenic distillation. Thus, in a second mode of operation, the plant can be used to liquefy the feed stream obtained from the generating device prior to storage. In addition, the equipment for performing the process according to the present invention may be movably connected to the air-gas distribution network.

Depending on the configuration adopted, the cold stream F recovered from the outlet 82 or 92 is fed to at least one pipe of the fluid distribution network 100 (in particular a network for distribution of hydrocarbons such as natural gas). do.

Preferably, the inlets and outlets of the condensing channels 3 , 7 are arranged such that the first and second working fluids W1 , W2 condense in opposite flow directions with respect to the cold flow F . Preferably, the hot streams C1 , C2 of the cycles flow in opposite flow directions with respect to the working fluid vaporized in each cycle. Preferably, the third stream C3 flows in the opposite flow direction, possibly with respect to the cold stream F flowing in the channel 9 . It should be noted that by continuously flowing in the third exchanger, the first exchanger, and possibly the fifth exchanger, the same hot stream can form C1, C2 or even C3.

This fluid flow direction makes it possible to maximize the outlet temperature of the working fluids W1 and W2 and thus maximize the power delivered by the turbine during expansion.

2 and those that follow illustrate a configuration in which the Rankine cycle is performed in an exchanger that forms physically distinct entities from one another (ie, each forming at least one distinct stack of channels and plates).

In the context of the present invention, it is also possible to arrange some of the fluid channels in the same stack. This can be devised in particular for exchangers of the brazed plate type, making it possible to reduce the manufacturing cost and complexity of equipment performing multiple combined Rankine cycles.

Thus, possibly together with the fifth exchange E5 , the first exchange E1 , the third exchange E3 may form the same common exchange and/or the second exchange E2 . and the fourth exchange E4 may form another common exchange.

In the case of a shared exchanger, when one series of channels and another series of channels are considered, through which the fluid flows continuously, each channel in the series forms an extension of the corresponding channel in the other series, thus: One identical channel of the exchanger E is formed between two identical plates. Accordingly, taking into account E1 and E3 forming the same exchanger, the second series of channels 2 and the sixth series of channels 6 are formed between the same plates of the exchanger E and are arranged successively with each other. . Channel 2 and channel 6 thus form one and the same channel of the exchanger E defined between two identical plates of the exchanger E, the hot stream C2 flowing from the inlet 61 to the outlet (22) flows.

When considering one series of channels and another series of channels through which different fluids flow, these channels are superimposed in the same stack, in a contiguous or non-adjacent manner.

4 and 5 show combinations of first and second Rankine cycles according to a second embodiment variant.

In the first operating mode of this variant, the second working fluid W2 with the second high pressure Hp2 flows into the at least one fifth channel 5 of the third exchanger E3, and the at least one second working fluid W2 6 It is at least partially vaporized for the at least one second hot stream C2 flowing in the channel 6 . The second working fluid W2 discharged from the channel 5 is expanded to a second low pressure Lp2 in the second expandable member which cooperates with the second generator to generate electrical energy.

The thus expanded second working fluid W2 flows into the second channel 2 , possibly in a two-phase state, and thus the first working fluid W1 flowing in the first channel 1 . form at least in part the hot flow of the first cycle for vaporizing the

The second working fluid W2 is condensed against at least the cold stream F flowing in the eighth channel 8 . After being discharged from the channel 2 , the pressure of the second working fluid W2 is raised to the second high pressure Hp2 , and the second working fluid W2 is reintroduced into the channel 5 .

The use of the second working fluid as the first hot stream of the first cycle allows for recovery in the second cycle of the precycle of vaporization occurring in the first cold cycle, during which liquefaction occurs in the second cycle. let there be Thus, the amount of energy recovered is greater than in an arrangement where these pre-rings are not upgraded, as the hot stream is simply cooled.

Also, in a series of arrangements as described with reference to FIG. 2 or FIG. 3 , the first cycle acts between the cold temperature of the cold stream and the temperature of the hot stream of the cycle. On the other hand, in a cascade arrangement in which a second working fluid is used as the first hot stream of the first cycle, as described with reference to FIG. 4 or FIG. 5 , the first cycle is performed with the cold temperature of the cold stream and It acts between the cold temperatures of the second cycle (which are lower than the temperatures of the hot streams). This provides the advantage of keeping the expansion rate technically acceptable and suitable for the turbine.

In the second mode of operation, the feed stream 200 is introduced into at least one eleventh channel 11 in heat exchange relationship with at least an eighth channel 8 before its entry into the tenth channel. Feed stream 200 is cooled with respect to cold stream F, optionally with at least partial condensation. Thus, a cooled feed stream 200 is obtained at the outlet of the eleventh channel 11 and subsequently introduced into the tenth channel 10 .

Optionally, feed stream 200 may optionally be introduced into at least one thirteenth channel 13 upstream of its entry into channel 11 , which in a second mode of operation, feed stream ( 200) allows for much more efficient cooling.

Note that the cold stream F may be fully or partially vaporized and/or heated in the second Rankine cycle (channel 4 ) by heat exchange with the second fluid W2 . The cold stream F may be fully or partially vaporized and/or heated in the first Rankine cycle by heat exchange with the first fluid W1 (channel 8 ).

Figure 4 shows the combination of cycles in which the condensed working fluid is re-entered into the condenser section before being re-introduced into the vaporizer section, and Figure 5 shows the combination in which the condensed working fluid is directly re-entered into the vaporizer section.

It is also possible to apply this combination of cycles without further passage of the condensed working fluid(s) through the condensing exchanger, as shown in FIG. 5 .

The same generator (not shown) connected to both the first expandable member of the first cycle and the second expandable member of the second cycle may be used, depending on the particular embodiment applicable to the first or second variant. Accordingly, the first generator and the second generator are merged. This saves the generator and simplifies the installation. This arrangement is possible, since the two power generation cycles have a largely simultaneous mode of operation.

In the context of the present invention, the cold stream F may be a stream of liquefied hydrocarbons, such as liquefied natural gas, or may be a stream of a cryogenic liquid, such as a liquid nitrogen stream, a liquid oxygen stream, or a liquid hydrogen stream.

Preferably, the inlet temperature of the cold stream F into the fourth channel 4 is less than -100°C.

Preferably, the cold stream F is from a stream of hydrocarbons (especially natural gas) comprising, preferably in mole fraction, at least 60% (preferably at least 80%) methane (CH ₄ ) is formed Optionally, natural gas, preferably in a content of 0 to 10% (mol %), is ethane (C ₂ H ₆ ), propane (C ₃ H ₈ ), butane (nC ₄ H ₁₀ ) or isobutane (iC) ₄ H ₁₀ ), or nitrogen. By means of the process of the present invention, the necessary regasification is performed prior to injecting the natural gas into the distribution network, while simultaneously upgrading the pre-ring of the liquefied natural gas.

Preferably, a cold stream of a different nature can be fed into the process according to the invention to be regasified before use. In particular, cryogenic liquids such as liquid oxygen, liquid nitrogen or liquid hydrogen may be used. According to the vaporization of this liquid, it is possible to ensure the continuity of the gas supply in case the manufacturing plant is shut down, and it is possible to save some of the energy consumed to form the liquid accumulator. Since the vaporization temperature of these constituents is much lower than that of natural gas, it may be desirable to perform a process combining three or more Rankine cycles, according to one of the preceding descriptions.

The cold stream to be regasified may be a cryogenic liquid at a cryogenic temperature (ie, a temperature that may be less than -170°C or even less than -200°C). In this case, the implementation of three or more cycles would be desirable.

Preferably, and when the fluid to be vaporized is LNG, the first working fluid W1 and the second working fluid W2 are organic fluids (ie a fluid comprising one or more organic components). The Rankine cycle of the process according to the present invention can also be devised which is not an organic cycle.

With the cryogenic liquid to be vaporized having a constituent having a boiling point lower than the boiling point of LNG, the working fluid of the cycle operating at the lowest temperature is hydrogen, nitrogen, argon, in addition to or in place of all or part of the organic compounds. , one or more components such as helium or neon. Thus, it is possible to devise an action through a working fluid free of organic components.

According to a first possibility, pure substances of different properties can be used to form the first fluid W1 and/or the second fluid W2 . In particular, ethylene may be used as the first working fluid W1 and ethane may be used as the second working fluid W2. This choice is explained by the good mechanical strength of the expansion turbine components and the brazed aluminum exchanger and the physical properties of these components with a saturated vapor pressure for the range of temperatures covered by the vaporization of LNG compatible with them. Therefore, by using these components in the ORC cycle, a simple and efficient system can be designed.

In the context of the present invention, working fluids of different compositions are preferentially used in the various Rankine cycles, but it is still possible to use working fluids of the same composition, in which case an appropriate adjustment of the working pressures of these fluids is made. This is possible for a relatively small temperature difference between the cold and hot streams of the cycle, for example, if the second cold stream is a very high pressure liquefied gas and the first hot stream is seawater at a sufficiently low temperature.

According to another possibility, a mixed working fluid comprising a hydrocarbon mixture, preferably each comprising at least two hydrocarbons selected from methane, ethylene (C ₂ H ₄ ), propane, ethane, butane, isobutane, or butene Mixed working fluids comprising hydrocarbon mixtures may be used. Optionally, the first working fluid W1 and the second working fluid W2 may include, in addition to or in place of the organic component, at least one additional component selected from hydrogen, nitrogen, argon, helium, and neon. and this is particularly the case if the cryogenic liquid to be vaporized has a boiling point lower than that of methane.

The use of a mixed working fluid makes it possible to reduce the energy loss associated with the irreversibility of heat exchange between the cold fluid and the hot fluid by reducing the temperature difference between the working fluid and the cold stream at each point along the length of the exchanger. The composition of each fluid, pressure before and after expansion, and/or temperature can be adjusted to ensure the best possible energy recovery.

When the working fluids are mixed, ie mixtures, they exit the liquid exchanger(s) cryogenically, in which case they are heated to maximize their outlet temperature to the high temperature limit and thus during their expansion in the turbine. In order to maximize the generation of electricity, it is desirable to reintroduce the condensed fluid into the exchanger(s) in question.

In particular, the proportion of the mole fractions (%) of the components of the first hydrocarbon mixture may be (mol%) as follows:

Methane: 20% to 60%, preferably 30% to 50%

Propane: 0 to 20%, preferably 0 to 10%

Ethylene: 20% to 70%, preferably 30% to 60%

The proportion of mole fractions (%) of the components of the second hydrocarbon mixture may be:

Methane: 0 to 20%, preferably 0 to 10%

Propane: 20% to 60%, preferably 30% to 50%

Ethylene: 20% to 60%, preferably 30% to 50%

Isobutane: 0 to 20%, preferably 0 to 10%

Preferably, the first hot stream (C1), the second hot stream (C2), and/or the third hot stream (C3) are introduced into the exchanger, preferably above 0 °C, preferably between 10 °C and 30 °C. At the inlet temperature of, seawater is formed.

Preferably, the low-temperature stream F is a hydrocarbon stream that is introduced in a completely liquefied state into the inlet 41 at a temperature of -140°C to -170°C.

If the cold stream F is formed of a liquid of another nature, such as liquid oxygen, nitrogen or hydrogen, the temperature of the fluid at the inlet 41 is preferably approximately its equilibrium temperature at the storage pressure.

Preferably, the cold stream F, for entering the distribution network 100 at this temperature, is at a temperature of -85° C. to -105° C. at the outlet 42 and -10° C. to -20° C. at the outlet 82 . C, and/or a temperature of 5 to 50 C at the outlet 92 . Preferably, the cold stream F is discharged in a fully vaporized state, as the case may be, via an outlet 42 , 82 or 92 .

Preferably, the cold stream has a pressure of 10 to 100 bar over the channel through which it flows.

Preferably, in the context of the present invention, the feed stream 200 has a temperature of from -170° C. to -140° C. at the outlet of the fourth channel 4 , from -110° C. to the outlet of the eighth channel 8 . a temperature of −80° C., and/or a temperature of −20° C. to −10° C. at the outlet of the ninth channel 9 .

Preferably, the first working fluid W1 has a first temperature T1 after being condensed in the third channel 3 . The second working fluid W2 , after being condensed in the seventh channel 7 , has a second temperature T2 , T2 being higher than T1 .

Preferably, T2 is -60°C to -30°C, and T1 is -110°C to -70°C. According to another possibility, T2 is between -110°C and -80°C and T1 is between -160°C and -120°C.

Preferably, the first working fluid W1 is discharged in a vaporized state from the at least one first channel 1 at a temperature of 0°C to -30°C, and the second working fluid W2 is 5 It is discharged in a vaporized state from the fifth channel 5 at a temperature of ℃ to 25 ℃.

Preferably, the first working fluid W1 and the second working fluid W2 are respectively at first and second “low pressures” Lp1, Lp2 in the third channel 3 and the seventh channel 7, respectively. It is discharged and flows into the first channel 1 and the fifth channel 5 at first and second "high pressures" Hp1 and Hp2, respectively.

Preferably, the first and/or second high pressures (Hp1, Hp2) are 10 to 40 bar and/or the first and/or second low pressures (Lp1, Lp2) are 1 to 5 bar. More preferably, the first high pressure Hp1 is higher/higher than the first low pressure Lp1 by a multiplication factor of 2.5 to 15, and the second high pressure Hp2 is the second high pressure Hp2 by a multiplication factor of 2.5 to 15. higher than the low pressure (Lp2). According to these values and pressure ratios, the process can be adjusted to the enthalpy curve of the fluid, and the equilibrium temperature can be optimally adjusted. The higher the working pressure, the greater the amount of energy recovered. A multiplication factor of at least 2.5 allows recovery of a sufficiently useful amount of energy. In practice, the pressure is limited by the capacity of the expandable member.

Needless to say, some or all of the features described above for the first and second working fluids are applicable where a single working fluid is used, for example in FIG. 1 .

To demonstrate the effect of the present invention, the energy yield obtained with a single Rankine cycle (Simulation No. 1), and the energy yield obtained with a combination of Rankine cycles according to an embodiment of the present invention (Simulation No. 2, No. 3 and No. 4) Simulations were performed to calculate

The cold stream was natural gas comprising 90.5% methane, 7.3% ethane, 1.5% propane, 0.2% butane, 0.3% isobutane, and 0.2% nitrogen (mol %).

Simulation number 1:

The switch configuration used is according to FIG. 1 . The only working fluid was propane. The pressure of the working fluid W1 was 7.5 bar at the inlet of the gasification exchanger and 1.5 bar at the outlet 32 of the condensing exchanger. The hot stream was seawater at a temperature of 23° C. and a pressure of 5 bar at the inlet of the gasification exchanger.

Simulation number 2:

The switch configuration used is according to FIG. 2 . The working fluid was pure substance. The first working fluid W1 was ethylene. The second working fluid was ethane. The pressure of the first working fluid W1 was 32 bar at the inlet 1a and 2 bar at the outlet 32 . The pressure of the second working fluid W2 was 27 bar at the inlet 51 and 5.8 bar at the outlet 72 . The natural gas pressure was 90 bar at the inlet 41 and 89 bar at the outlet 92 . The hot stream C1, C2, C3 was seawater at the inlet and outlet of channels 2, 6 and 12 at a pressure of 5 bar. Table 1 shows the calculated fluid temperatures at the inlet or outlet of the different channels.

[Table 1]

Simulation number 3:

The exchange configuration used is according to FIG. 3 . The first working fluid (W1) was a hydrocarbon mixture comprising 53% ethylene, 41% methane, and 6% propane (mol%). The second working fluid (W2) was a hydrocarbon mixture comprising 46% ethylene, 38% propane, 8% methane, and 8% isobutane (mol %). The pressure of the first working fluid W1 was 31.0 bar at the inlet 23 and 1.8 bar at the outlet 32 . The pressure of the second working fluid W2 was 12.4 bar at the inlet 43 and 4.6 bar at the outlet 72 . The natural gas pressure was 90 bar at the inlet 41 and 89.5 bar at the outlet 82 . The hot stream C1, C2, C3 was seawater at the inlet and outlet of channels 2, 6 and 12 at a pressure of 5 bar. Table 2 shows the calculated fluid temperatures at the inlet or outlet of the different channels.

[Table 2]

Simulation number 4:

The switch configuration used is according to FIG. 5 . The working fluid was a pure substance. The first working fluid W1 was ethylene. The second working fluid was ethane. The pressure of the first working fluid W1 was 8.1 bar at the inlet 1a and 2.1 bar at the outlet 32 . The pressure of the second working fluid W2 was 27 bar at the inlet 51 and 5.8 bar at the outlet 22 . The natural gas pressure was 90 bar at the inlet 41 and 89 bar at the outlet 92 . The hot stream C2 was seawater at a pressure of 5 bar at the inlet and outlet of the channel 6 . Table 3 shows the calculated fluid temperatures at the inlet or outlet of the different channels.

[Table 3]

Simulation number 5:

The switch configuration used is according to FIG. 4 . The first working fluid (W1) was a hydrocarbon mixture comprising 55.4% ethylene, 41% methane, and 3.6% propane (mol %). The second working fluid was a hydrocarbon mixture comprising 46% ethylene, 38% propane, 8% methane, and 8% isobutane. The pressure of the first working fluid W1 was 16.7 bar at the inlet 141 and 1.7 bar at the outlet 32 . The pressure of the second working fluid W2 was 12 bar at the inlet 151 and 4.2 bar at the outlet 22 . The natural gas pressure was 90 bar at the inlet 41 and 89.5 bar at the outlet 82 . The hot stream C1 was seawater at a pressure of 5 bar at the inlet and outlet of the channel 2 . Table 4 shows the calculated fluid temperatures at the inlet or outlet of the different channels.

[Table 4]

In simulation number 1, the energy yield obtained with the first process mode of operation was 0.016 kWh/Nm ³ .

In simulation No. 2, the energy yield obtained with the first operating mode of the first cycle was 0.0114 kWh/Nm ³ , and the energy yield of the second Rankine cycle was 0.0049 kWh/Nm ³ (i.e., about 2 compared to simulation No. 1). % of the total process yield of 0.01634 kWh/Nm ³ ).

In simulation number 3, the energy yield of the first Rankine cycle was 0.016 kWh/Nm ³ , and the energy yield of the second Rankine cycle was 0.011 kWh/Nm ³ (i.e., representing a gain of about 68% compared to simulation number 1, a total yield of 0.027 kWh/Nm ³ ).

In simulation number 4, the energy yield of the first Rankine cycle was 0.0045 kWh/Nm ³ , and the energy yield of the second Rankine cycle was 0.0134 kWh/Nm ³ (i.e., representing a gain of about 12% compared to simulation number 1, total yield of 0.0179 kWh/Nm ³ ). In simulation number 5, the energy yield of the first Rankine cycle was 0.012 kWh/Nm ³ , and the energy yield of the second Rankine cycle was 0.021 kWh/Nm ³ (i.e., representing a gain of about 106% compared to simulation number 1, total yield of 0.033 kWh/Nm ³ ).

In each case, the process was simulated in both modes of operation. For example, consider a process according to simulation number 5. In the first mode of operation, the flow rate of the first working fluid was 1055 Nm ³ /h and the flow rate of the second working fluid was 3617 Nm ³ /h.

In the second operating mode, the flow rate of the first working fluid was 927 Nm ³ /h (ie a 12% decrease (relative difference) compared to the first operating mode) and the flow rate of the second working fluid was 3400 Nm ³ /h (ie 6% reduction (relative difference) compared to the first mode of operation). A feed stream 200 formed of nitrogen was introduced into the E3 exchanger. It had a temperature of about 20° C. and a pressure of about 35 bar at the inlet of the second exchanger E2.

A liquefied feed stream 201 was obtained at the outlet of the second exchanger, said stream 201 having a temperature of about -150° C. and a pressure of about 34.5 bar.

At a flow rate of about 3000 Nm ³ /h of LNG, with a storage temperature of -170° C. and a storage pressure of 10 bar after pre-flash expansion, it was possible to store about 175 Nm ³ /h of nitrogen in the tank 203 . . In addition, this generation of liquid nitrogen was accompanied by the generation of electricity of about 0.029 kWh/Nm ³ LNG (ie a reduction of 0.004 kWh/Nm ³ of generated electrical energy compared to simulation number 5 in the first mode of operation alone). .

It should be noted that the use of mixed first and second working fluids greatly increases the performance of the process by improving the exchange diagram between the liquefied natural gas and the working fluid.

By way of example, FIG. 6 shows on the one hand a combination of cycles through a pure working fluid according to simulation number 4 (in (a)) and on the other hand a combination of cycles through a mixed working fluid according to simulation number 5 A comparison of the heat exchange-temperature (ΔH-T) exchange diagram or enthalpy curve, obtained with (b), is shown. The plots shown are obtained for a flow rate of treated LNG of 3000 Nm ³ /h (ie about 1/100 scale of an industrial unit). Curves A, B, C, D show, for each of the two simulated configurations, all heat generating fluids that are cooled and/or condensed in the process, including first and second working fluids (curves B and D), and For all refrigerant fluids heated and/or vaporized in the process and natural gas, including LNG (curves A and C), the release of heat exchanged as a function of temperature is shown respectively. 6b) it can be seen that by using a working fluid composed of a mixture of constituents, which accounts for the greater efficiency of this cycle, the mean temperature difference is greatly reduced.

Needless to say, the present invention is not limited to the specific embodiments described and illustrated in this patent application. In addition, other modifications or embodiments within the scope of those skilled in the art can be devised without departing from the scope of the present invention. For example, other configurations of injection and extraction of fluids from the exchanger(s), other directions of flow of fluids, other types of fluids, and the like may be devised.

Claims (21)

A process for recovering refrigeration energy from a cold stream (F) in a system, comprising:
The system comprises a storage tank (203), at least one generator (G), and at least one heat exchange device comprising a plurality of channels configured to flow a fluid into a heat exchange relationship;
The process, in a first mode of operation,
a) at least one second channel that introduces a first working fluid W1 having a first high pressure Hp1 into the at least one first channel 1 and is in heat exchange relationship with the at least one first channel 1 . vaporizing at least a portion of the first working fluid (W1) with respect to the at least one first hot stream (C1) flowing in (2);
b) in a first expandable member cooperating with a first generator to deliver the first working fluid W1 obtained in step a) from the first channel 1 to generate electrical energy, a first low pressure Lp1 ), wherein Lp1 is less than Hp1;
c) at least one fourth channel (4) introducing the first working fluid (W1) expanded in step b) into at least one third channel (3) and in heat exchange relationship with at least the third channel (3) condensing at least a portion of the first working fluid (W1) with respect to at least the cold stream (F) flowing in the
d) passing the first working fluid W1 at least partially condensed in step c) from the third channel 3 , the pressure of the first working fluid W1 up to the first high pressure Hp1 raising and re-introducing into the first channel (1),
The process, in a second mode of operation,
e) introducing a feed stream (200) into at least one tenth channel (10) in heat exchange relationship with said fourth channel (4);
f) at the outlet of the tenth channel (10), condensing at least a portion of the feed stream (200) with respect to the cold stream (F) to produce an at least partially liquefied feed stream (201). step; and
g) filling the storage tank (203) with the feed stream (201) produced in step f).
A process for recovering refrigeration energy from the cold stream (F) in the system. The method of claim 1,
h) introducing the feed stream (201) obtained from step f) into a supercooler (205);
i) passing the feed stream (201) from the subcooler (205) and expanding it in a third expandable member (202) to form a gaseous phase (204) and a liquid phase of the feed stream (201); ;
j) introducing the gaseous phase (204) and the liquid phase into the storage tank (203);
k) extracting at least a portion of the gas phase (204) from the storage tank (203) to cool the feed stream (201) flowing in the subcooler (205) by heat exchange with the gas phase (204); flowing into the supercooler (205);
l) compressing the gaseous phase 204 in a compression device to form a compressed gaseous phase 206 , and prior to introducing it into the tenth channel 10 , the compressed gaseous phase 206 into the feed stream 200 . ), characterized in that it further comprises the step of introducing. 3. The method of claim 1 or 2,
The cold stream (F) discharged from the fourth channel (4) is introduced into at least one eighth channel (8),
The process, in the first mode of operation,
m) at least one sixth channel (6) for introducing a second working fluid (W2) having a second high pressure (Hp2) into the at least one fifth channel (5) and in heat exchange relation with at least the fifth channel (5) ) vaporizing at least a portion of the second working fluid (W2) with respect to the at least one second hot stream (C2) flowing in;
n) in a second expandable member cooperating with a second generator to deliver said second working fluid (W2) at least partially vaporized in step m) from said fifth channel (5) to produce electrical energy, a second expanding to a low pressure (Lp2), wherein Lp2 is lower than Hp2;
o) introducing the second working fluid W2 expanded in step n) into at least one seventh channel 7 in heat exchange relationship with the eighth channel 8 , and flowing in the eighth channel 8 . condensing at least a portion of the second working fluid (W2) with respect to the low temperature stream (F);
p) passing the second working fluid W2 at least partially condensed in step g) from the seventh channel 7 , thereby reducing the pressure of the second working fluid W2 to the second high pressure Hp2 raising and re-introducing the second working fluid (W2) into the fifth channel (5);
The process, in the second mode of operation,
q) before step f), introducing the feed stream (200) into at least one eleventh channel (11) in heat exchange relationship with the eighth channel (8);
r) cooling the feed stream 200 with respect to the cold stream F so as to obtain a cooled feed stream 200 at the outlet of the eleventh channel 11, with possible condensation of at least a portion; , introducing the cooled feed stream (200) into the tenth channel (10). 3. The method of claim 1 or 2,
The cold stream (F) discharged from the fourth channel (4) is introduced into at least one eighth channel (8),
The process, in the first mode of operation,
s) at least one sixth channel (6) for introducing a second working fluid (W2) having a second high pressure (Hp2) into the at least one fifth channel (5) and in heat exchange relationship with at least the fifth channel (5) ) vaporizing at least a portion of the second working fluid (W2) with respect to the at least one second hot stream (C2) flowing in;
t) in a second expandable member cooperating with a second generator to deliver said second working fluid (W2) at least partially vaporized in step s) from said fifth channel (5) to produce electrical energy, a second expanding to a low pressure (Lp2), wherein Lp2 is lower than Hp2;
u) introducing the second working fluid W2 expanded in step t) into the second channel 2 , and at least for the cold stream F flowing in the eighth channel 8 , the second condensing at least a portion of the working fluid (W2);
v) delivering the second working fluid W2 that is at least partially condensed in step u) from the second channel 2 to increase the pressure of the second working fluid W2 to a maximum of the second high pressure Hp2 and re-introducing the second working fluid (W2) into the fifth channel (5),
the first hot stream (C1) flowing in step a) is formed at least in part by the second working fluid (W2) flowing in step u) in the second channel (2),
The process, in the second mode of operation,
w) before step f), introducing said feed stream (200) into at least one eleventh channel (11) in heat exchange relationship with said eighth channel (8);
x) cooling the feed stream 200 with respect to the cold stream F to obtain a cooled feed stream 200 at the outlet of the eleventh channel 11, with at least some possible condensation and introducing the cooled feed stream (200) into the tenth channel (10). 5. The method according to any one of claims 1 to 4,
the first working fluid (W1) and/or the second working fluid (W2) is an organic fluid,
the first working fluid (W1) and/or the second working fluid (W2) comprises a first hydrocarbon mixture and a second hydrocarbon mixture, respectively,
The first and second hydrocarbon mixtures are preferably methane, ethane, propane, butane, ethylene, propylene, butene, optionally with the addition of at least one additional component selected from nitrogen, argon, helium, carbon dioxide, and neon. and at least two hydrocarbons selected from isobutane. 5. The method according to any one of claims 1 to 4,
the first working fluid (W1) and/or the second working fluid (W2) is an organic fluid,
Process, characterized in that the first working fluid (W1) and/or the second working fluid (W2) are pure substances consisting respectively of a first hydrocarbon and a second hydrocarbon. 7. The method according to any one of claims 1 to 6,
Process, characterized in that the feed stream (200) is formed mostly, preferably completely or almost completely, of an air gas, preferably nitrogen, oxygen or argon. 8. The method according to any one of claims 1 to 7,
The process according to claim 1 , wherein the cold stream (F) is a stream of liquefied hydrocarbons, such as liquefied natural gas, or a stream of a cryogenic liquid selected from a stream of liquid nitrogen, a stream of liquid oxygen, a stream of liquid hydrogen. 9. The method according to any one of claims 1 to 8,
The first hot stream (C1), the second hot stream (C2), and/or the third stream (C3) is of seawater, preferably, exactly above 0 °C, preferably between 10 °C and 30 °C. It is formed by seawater flowing into the temperature,
Process, characterized in that the seawater is optionally subjected to a preheating step. 10. The method according to any one of claims 1 to 9,
The process, characterized in that the process is carried out selectively according to the first mode of operation or the second mode of operation. 11. The method of claim 10,
the selection of the first or second operating mode is carried out according to the value of at least one parameter indicating the amount of electricity demand;
Preferably, the process comprises at least one step of determining at least one value of electrical energy and/or instantaneous power consumed via an electrical supply network and/or by an industrial plant,
wherein the process is carried out in the first mode of operation if the value is greater than or equal to a predetermined threshold or is carried out in the second mode of operation if the value is less than the predetermined threshold. 12. The method according to any one of claims 1 to 11,
In the second mode of operation, the flow rate of at least one of the first hot stream C1 , the second hot stream C2 , the first working fluid W1 , and/or the second working fluid W2 . is reduced or even stopped. 10. The method according to any one of claims 1 to 9,
the process is performed simultaneously in the first mode of operation and the second mode of operation to simultaneously produce electrical energy and an at least partially liquefied feed stream (201);
The process, characterized in that it comprises at least one step of adjusting the operation by at least a change in the flow rates of the first working fluid (W1) and/or the second working fluid (W2). 14. The method according to any one of claims 1 to 13,
Process, characterized in that the feed stream (201) obtained from step f) has a pressure of at least 5 bar, preferably at least 20 bar, more preferably at least 30 bar. 15. The method according to any one of claims 1 to 14,
The cold stream F exiting the eighth channel 8 is directed therein with respect to the second hot stream C2, the second working fluid W2, and/or the third hot stream C3. to be heated, introduced into at least one ninth channel (9),
characterized in that the feed stream (200) enters at least a thirteenth channel (13) in heat exchange relationship with at least the ninth channel (9) before its introduction into the eleventh channel (11). fair. 16. The method according to any one of claims 1 to 15,
The process, characterized in that the cold stream (F) and the feed stream (200) flow in opposite flow directions. 17. The method according to any one of claims 1 to 16,
The first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth and/or thirteenth channels are at least one of the brazing plate type. forming part of the heat exchanger of
wherein said exchanger comprises a stack of a plurality of parallel plates spaced apart to define a plurality of series of a plurality of channels therebetween. 18. The method according to any one of claims 1 to 17,
The feed stream 200 is introduced in gaseous form into the tenth channel 10 , the eleventh channel 11 , and/or the thirteenth channel 13 , preferably at -200°C to -130 ℃, preferably -170 ℃ to -130 ℃, more preferably at a temperature of -160 ℃ to -140 ℃, characterized in that discharged from the tenth channel 10 in a completely condensed state, fair. A facility for recovering refrigeration energy from a cold stream (F) in a system, comprising:
The system comprises a storage tank (203), at least one generator, and at least one heat exchange device comprising a plurality of channels configured to flow a fluid into a heat exchange relationship;
The equipment is
- at least one first channel (1) configured to flow a first working fluid (W1);
- at least one second channel (2) configured to flow a first hot stream (C1), said second channel (2) having, in a first mode of operation, said second channel (2) introduced into said first channel (1) at least one second channel (2) in heat exchange relationship with said first channel (1) such that a first working fluid (W1) is at least partially vaporized with respect to said first hot stream (C1);
- Reduces the pressure of the first working fluid W1 disposed downstream of the first channel 1 and discharged from the first channel 1 from the first high pressure Hp1 to the first low pressure Lp1 a first expandable member configured to
- a generator connected to said first expandable member;
- at least one third channel (3) arranged downstream of said first expandable member and configured to flow said first working fluid (W1) expanded by said first expandable member;
- at least one fourth channel (4) configured to flow a cold stream (F), said fourth channel (4) having, in said first mode of operation, said third channel (3) introduced into said third channel (3) 1 at least one fourth channel (4) in heat exchange relationship with the third channel (3), such that the working fluid (W1) is at least partially condensed with respect to the at least partially vaporized cold stream (F);
- the pressure of the first working fluid W1 disposed downstream of the third channel 3 and discharged from the third channel 3 from the first low pressure Lp1 to the first high pressure Hp1 a first pressure-raising member configured to increase to
- at least one tenth channel (10) configured to flow a feed stream (200), said channel (10), in a second mode of operation, said feed stream introduced into said tenth channel (10) at least one tenth channel (10) in heat exchange relationship with said channel (4) such that (200) is at least partially condensed with respect to said cold stream (F); and
- characterized in that it further comprises a storage tank (203) movably connected to the tenth channel (10),
Equipment for recovering refrigeration energy from the cold stream (F) in the system. 20. The method of claim 19,
- at least one fifth channel (5) configured to flow a second working fluid (W2);
- at least one sixth channel (6) configured to flow a second hot stream (C2), said sixth channel (6) having, in said first mode of operation, introduced into said fifth channel (5) at least one sixth channel (6) in heat exchange relationship with said fifth channel (5) such that said second working fluid (W2) is at least partially vaporized with respect to said second hot stream (C2);
- Decrease the pressure of the second working fluid W2 disposed downstream of the first channel 1 and discharged from the fifth channel 5 from the second high pressure Hp2 to the second low pressure Lp2 a second expandable member configured to
- a second generator connected to said second expandable member;
- at least one second channel (2) arranged downstream of said second expandable member and configured to flow said second working fluid (W2) expanded by said second expandable member;
- at least one eighth channel (8) configured to flow the cold stream (F), said eighth channel (8), in said first mode of operation, said channel (8) introduced into said second channel (2) at least one eighth channel (8) in heat exchange relationship with said second channel (2) such that a second working fluid (W2) is at least partially condensed with respect to said cold stream (F) being at least partially vaporized;
- the pressure of the second working fluid W2 disposed downstream of the second channel 2 and discharged from the second channel 2 from the second low pressure Lp2 to the second high pressure Hp2 a second pressure-raising member configured to increase to ;
- at least one eleventh channel (11) configured to flow the feed stream (200), said eleventh channel (11) being, in a second mode of operation, introduced into said tenth channel (10) in heat exchange relationship with the eighth channel (8) such that the feed stream (200) is cooled with respect to the cold stream (F) before entering the tenth channel (10) and optionally at least partially condensed; Equipment, characterized in that it further comprises at least one eleventh channel (11). As a system,
The system is
the installation according to claim 19 or 20;
A production device, formed by a production device, such as a cryogenic distillation air separation device, suitable for producing a feed stream ( 200 ) at at least one outlet of the production device;
wherein the at least one outlet is flowably connected to the facility;
system.

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