JP7018946B2 - Closed gas cycle in cryogenic applications or cooling fluids - Google Patents

Description

The present invention finds applications in the energy field, especially for reducing energy consumption required for liquefied gas regasification terminals.

Techniques for regasifying liquefied natural gas (LNG) are known.

Liquefied natural gas is a mixture of natural gas primarily containing methane and, to a lesser extent, ethane, propane, isobutane, n-butane, pentane, and other light hydrocarbons such as nitrogen, at room temperature. The gas state found is converted to a liquid state at about -160 ° C and its transport is possible.

The liquefaction plant is located near the natural gas production site, while the regasification plant (or "regasification terminal") is located near the user.

Most plants (about 85%) are located on land and the rest (about 15%) are on the platform or offshore.

Each regasification terminal shall be equipped with several regasification lines to meet the load or requirements of liquefied natural gas, and for flexibility or technical requirements (eg, to maintain the line). Is common.

Regasification techniques typically include liquefied natural gas stored at atmospheric pressure in a tank at a temperature of -160 ° C, with gas compression steps up to about 70-80 bar and vaporization and overheating up to about 3 ° C. Including the steps of.

The thermal power required for regasification of 139 t / h is about 27 MWt (megawatt) and the power is about 2.25 MW (megawatt) (4.85 MW when considering other auxiliary loads of the plant, 4). The maximum electrical load of the plant on one regasification line is 19.4 MW).

Of these, the most used are the Open Rack Vaporizer (ORV) technology, which is used individually or in combination with each other in about 70% of regasification terminals, and the Underwater Combustion Vaporizer (SCV). Is.

Open rack vaporizer (ORV)
This technique provides that natural gas in a liquid state (about 70-80 bar and a temperature of 160 ° C.) is allowed to flow upward from the bottom in a side-contacting aluminum tube to form a panel. Vaporization occurs progressively as the fluid progresses.

The heat medium is seawater, and by flowing downward from the upper part on the outer surface of the pipe, the heat required for vaporization is provided by the temperature difference.

In particular, heat exchange is optimized by the design of the tube outline and surface roughness, which performs a uniform distribution of thin seawater membranes on the panel.

Underwater Combustion Vaporizer (SCV)
Such techniques utilize desalinated water heated by an underwater flame burner as a heat medium. In particular, the fuel gas (FG) is burned in the combustion section, and the generated evaporative air passes through the coil of the perforated pipe from which the bubbles of the combustion gas come out, heating the water bath and also the heat of condensation. introduce.

Liquefied natural gas (LNG) is vaporized in another coil of stainless steel pipe submerged in the same desalting and heated water bath.

The same water bath is kept in circulation to ensure a uniform temperature distribution.

On the other hand, the discharged evaporative air is discharged by the vent stack of the SCV.

Italian Patent No. 10427993 (Snaprogetti S.p.A.) describes a method for the simultaneous generation of electrical energy by a nitrogen closed gas cycle (Brayton) that recovers heat from the regasification of LNG and the emissions of gas turbines. Is explained.

However, such methods are limited in use because they generate a larger amount of electrical energy than the requirements of the regasification terminal. A calculated yield of 55% yields 33 MW, which is 10 times what is needed.

Moreover, it can only be used to utilize gas turbines to recover heat from exhaust gases. It also requires a compression ratio equal to 10, and therefore requires the use of fairly complex machines, compressors, and multi-stage turbines, which operate at high temperatures (400-700 ° C) and also use expensive materials. do.

Other drawbacks and limitations are represented by the fact that the ratio of thermal load to electrical load is strongly imbalanced with respect to the thermal moiety. Therefore, in order to cover the thermal load and the electric load at the same time, most of the heat recovered from the gas turbine is released by the closed gas cycle, and the inefficient closed gas cycle is executed. In addition, in situations where the flow rate of LNG is low, some of the turbine emissions into the atmosphere is due to choke the turbine load, with additional efficiency loss or still loss of efficiency in the system. Need to be released.

With particular reference to underwater combustion vaporizers (SCVs), such techniques mean fuel gas consumption equal to about 1.5% of the gas produced, lowering the pH of baths that require treatment with caustic soda. Determine the amount of CO ₂ produced at about 50,000 tons / year to produce carbon dioxide and regasify 139 tons / hour.

Instead, for open rack vaporizers, such techniques can partially cause freezing of seawater in the outer part of the tube, especially in sections where LNG is colder. In addition, i) it may be used in the geographic area and / or in the season when the seawater temperature is at least 5-9 ° C, represented primarily by the subtropical zone, ii) seawater corrodes the zinc coating on the tube. Must be pre-treated to eliminate or reduce the content of possible heavy metals, iii) This must overcome a level of geographic difference equal to the development of the height of the ORV, seawater pump. Means electrical energy consumption to operate, which entails an additional consumption of 1.2 MW per regasification line compared to SCV technology (total plant power equals 24.2 MW), iv) Finally, This technique is very complex and is available in a limited number of suppliers and sizes.

Therefore, in general, conventional techniques do not allow the plant to generate the required electrical energy, resulting in a large loss of energy in the form of a cooling unit.

The authors of the present invention have surprisingly found that it is possible to introduce a closed gas cycle into a conventional regasification line.

The first object is to illustrate a regasification line for liquefied natural gas (LNG).

Another object of the present invention is to illustrate a method for generating thermal energy and electrical energy.

A further object is to describe a regasification terminal equipped with a regasification plant for liquefied natural gas (LNG).

It is a figure which shows the regasification line by this invention. It is a diagram showing a plant with more regasification lines that illustrates the concept of energy bypass. It is a figure which shows the regasification line by the alternative embodiment of this invention. It is a figure which shows the regasification line by another alternative embodiment of this invention. It is a figure which shows the alternative structure of a part of the regasification line of this invention. It is a figure which shows another alternative structure of a part of the regasification line of this invention. It is a figure which shows another alternative structure of a part of the regasification line of this invention. It is a figure which shows the regasification line by the further embodiment of this invention. It is a figure which shows the regasification line by the further embodiment of this invention.

Although the present invention has specifically described the regasification of liquefied natural gas (LNG), the regasification lines, regasification terminals and regasification methods described below may be at low temperatures (less than about 0 ° C.) or. It can also be applied to the regasification or vaporization of other liquefied fluids stored at extremely low temperatures (less than −45 ° C.).

In the following description, the term "liquefied gas" is intended primarily to mean a fluid of liquid constituents.

The present invention regasses or vaporizes, or hydrogenates, a liquefied gas selected from the group comprising, for example, air, nitrogen, hydrocarbon compounds such as alkanes such as propane and butane, or alkenes such as ethylene and propylene. Similar applications will be found for regasification or vaporization.

For the sake of brevity, natural gas is referred to in this description and drawings.

According to an object of the present invention, a regasification line for liquefied natural gas (LNG) is described.

The term "regasification line" is intended to mean a plant portion equipped with structures, equipment, machinery and systems for the regasification of liquefied natural gas (LNG).

Such structures, equipment, machines, and systems are specifically derived from tanks where LNG is stored and ends at the inlet point of the regasified LNG within the distribution network of the gas itself.

More specifically, in the tank, liquefied natural gas (LNG) is stored at atmospheric pressure at a temperature of about −160 ° C.

In particular, the liquefied gas tank can be located in a location or structure other than the regasification plant, which may be, for example, onshore or offshore or on a floater.

The circuit element is the bath in the underwater combustion vaporization (SCV) section.

Prior to entering the vaporization bath, the LNG can be subjected to a precompression step to a pressure of about 70-80 bar.

The compression is driven by a low pressure pump (about 400 kW) and a high pressure pump (about 1300 kW) operating in series (PMP1 in FIG. 4).

In FIG. 1, CMP1 represents a boil-off gas compressor (BOG).

In a preferred embodiment, at the bath inlet of the SCV section, the liquefied gas may be in a supercritical state. For example, in the case of liquefied natural gas, this can be a pressure of about 70-80 bar and a temperature of about -155 ° C.

In the SCV bath, the liquefied natural gas is vaporized and superheated to a temperature of up to about 3 ° C.

Once regasified, natural gas can be introduced into the natural gas distribution network.

According to the first object of the present invention, the regasification line (base circuit) of liquefied natural gas is modified to integrate the liquefied natural gas (LNG) bypass circuit.

In particular, the integration between the two circuits is at the lead-in coupling of liquefied natural gas from the base circuit and at the re-introduction coupling of regasified liquefied natural gas in the base circuit towards the distribution network.

Preferably, the draw-in connection is downstream of the cryogenic pump and upstream of the vaporization bath (SCV).

Therefore, for the purposes of the present invention, the following will be described:
-Existing regasification line (modification) modified to integrate the natural gas regasification bypass circuit, and-for example, a regasification line consisting of a bypass circuit, which is the main line for building a new plant. ..

Liquefied Natural Gas (LNG) Bypass Circuit A portion of the LNG flow (101) as output from the storage tank is optionally withdrawn from the LNG base circuit after a precompression step and heated in the heat exchanger (HE1). And the vaporization step.

In particular, such heating is operated up to a temperature of about 3 ° C.

The natural gas stream (102) thus vaporized is introduced into the natural gas network at a pressure of about 70 bar and 3 ° C.

According to one aspect of the present invention, a portion (103) of LNG as an output from the exchanger HE1 is sent to a boiler (natural gas-fired boiler).

Considering the initial LNG flow rate of about 139 t / h, the amount intended for the boiler circuit is about 1-2 t / h.

According to a first object of the invention, the liquefied natural gas (LNG) circuit with the base circuit and bypass circuit described above is modified by introducing (or integrating with) a closed gas cycle.

Closed Gas Cycle According to the present invention, a closed gas cycle operates with a fluid, preferably a monatomic gas, called a working fluid.

In an even more preferred embodiment, the gas is selected from the group comprising argon, nitrogen, helium, and air.

For the purposes of the present invention, such a working fluid is argon (Ar).

The working fluid 1 at a temperature of about 70 ° C. and a pressure of about 20 bar is subjected to compression steps up to about 42 bar via the compressor K1 to a compression ratio of about 2 (more accurately 2.09). ..

In a closed gas cycle, the determinant is the compression ratio, but the design of the turbomachine (the size decreases due to the decrease in volume flow as the pressure increases) and the thickness of the tube increases as the pressure increases. In the equipment, the minimum and maximum pressures (connected to each other by compression ratio) are optimized.

The flow 2 thus obtained is heated to a maximum of about 4 ° C. in the heat exchanger (HE3 in FIG. 1).

This step involves heat exchange equal to about 12 MWt.

For the purposes of the present invention, the heat exchange step in the third heat exchanger HE3 is optional.

Subsequently, the heated stream (3 in FIG. 1) is heated in the heat exchanger (HE2 in FIG. 1) or optionally further heated to obtain a stream 4 at about 120 ° C.

This step involves heat exchange equal to about 18 MWt.

In the next step, the working fluid flow 4 expands up to about 21 bar in the turbine T2 fitted to the generator G1 and the compressor K1 and is cooled to about 40 ° C. (flow 5 in FIG. 1). It provides a net power of about 2.25 MW.

Finally, within the exchanger HE1, the working fluid of the closed gas cycle transfers heat output to the LNG for cooling of about 27 MWt.

In a preferred embodiment of the present invention, the working fluid flow rate of the closed gas cycle circulating in the circuit is about 137.8 t / h.

For the purposes of the present invention, heat exchange occurs in the heat exchanger HE1, which causes the working fluid of the closed gas cycle to transfer the heat output to the liquefied natural gas (LNG), thus regassing the liquefied natural gas. ..

In such a step, heat exchange corresponding to about 27 MWt occurs.

According to an alternative aspect of the invention shown in FIG. 5A (where C = compressor, R1 = first reducer, T1 = turbine, R2 = second reducer, and G = generator). And the closed gas cycle compressor can be fitted directly on the same shaft. Moreover, they may or may not have the same rotational speed, and they can transfer mechanical energy to one and the same generator.

In another embodiment shown in FIG. 5B (where C = compressor, R1 = first reducer, T1 = turbine, T2 = second turbine, R2 = second reducer, and G = generator). The working fluid can expand in two turbines in series: T1 which operates at high pressure to match the compressor and T2 which operates at low pressure to match the generator.

In another alternative embodiment shown in FIG. 6, the compressor K1 is electrically operated and the turbine T2 is fitted only to the generator.

In another alternative not shown, a heat exchanger (recoverer) is inserted into the output of the turbine and the working fluid after expansion in the turbine is from the heat exchanger HE3 before receiving heat from the exchanger HE2. Transfers heat to the output of the working fluid.

According to a further aspect of the invention, the working fluid circuit may be further integrated with additional circuits.

In particular, such circuits can include:
-Boiler circuit,
-Circuit for recovering heat from "fuel cell",
-Seawater circuit,
-A circuit for recovering the heat of compression from the BOG compressor.

According to a preferred embodiment of the invention, integration is possible in any one or more of those cycles listed above.

Water having a temperature of about 30 ° C. is supplied to the boiler circuit or the first high temperature circuit circuit (201 in FIG. 1).

The water stream 202 reaches the boiler at a pressure of about 3.82 bar and is circulated by the circulation pump of the boiler PMP3 of FIG. The stream 203 of water heated to about 140 ° C. in the boiler is cooled in the heat exchanger (HE2), which is cooled to about 30 ° C. (201).

According to a preferred embodiment of the invention, the boiler circuit is integrated with the closed gas cycle in the exchanger HE2, in which the boiler circuit water becomes the working fluid of the closed gas cycle whose heat output has been raised to about 120 ° C. Communicate and cool.

Such steps specifically include heat exchange equivalent to about 18 MWt.

In an alternative aspect of the invention, the boiler may be replaced by an equivalent heat source.

According to an alternative aspect of the invention, the superheated water boiler circuit may be replaced by a diathermy oil circuit.

The choice of one or the other method may be made based on the need.

In one aspect of the invention shown in FIG. 8, the boiler circuit operates with an intermediate fluid represented by the exhaust evaporative air (203 in FIG. 8) of the boiler itself to which air is supplied.

In particular, in the heat exchanger HE2, heat exchange occurs together with the evaporative air output from the boiler to generate the evaporative air sent to the stack 201.

The working fluid output from the exchanger HE2 is heated in the boiler, and the flow 4 is subsequently sent to the turbine T2.

In such a configuration, heat exchange is caused by radiation in the boiler and convection in the exchanger HE2 (the point of integration with the working fluid cycle).

In the embodiments described above, the preferred working fluid is nitrogen.

In an alternative aspect of the invention, the boiler as a heat source is a fuel cell and its exhaust fluid can transfer heat.

The feed fluid of the fuel cell can be hydrogen, ethanol, methane.

The seawater circuit or the second low temperature circuit seawater is drawn out at the seawater outlet at a temperature of about 9 ° C. (301 in FIG. 1).

It is subsequently pumped to a pressure of up to about 2 bar (302 in FIG. 1) using the pump PMP2 and then cooled to about 4 ° C. in a third heat exchanger (HE3).

This cooling step in HE3 involves the transfer of thermal energy of approximately 12 MWt.

Under these conditions, the water stream (303) can be released into the sea.

Optionally, prior to introduction into the circulatory system, seawater is filtered to retain substances and organic materials such as algae, mollusks, and inorganic materials such as sand or particulate matter.

According to a preferred embodiment of the invention, the integration with the closed gas cycle occurs in the third heat exchanger HE3, where seawater transfers heat to the working fluid of the closed gas cycle.

Such steps specifically include heat exchange corresponding to about 12 MWt.

It will be found that the heat exchange step in the third heat exchanger (HE3) corresponds to the step described above for heating the working fluid of the closed gas cycle.

By integrating the closed gas cycle with the seawater circuit, it becomes possible to utilize the second heat source at low temperature and reduce the consumption of regasified natural gas.

In this description, when referring to "seawater", this is not only the pumped seawater, the one that is properly treated to remove sediments, but more generally rivers, canals, wells, lakes, etc. It also means to refer to fresh water obtained from natural basins or artificial basins of.

In an alternative embodiment of the invention, ambient air can be used as a low temperature heat source instead of seawater, for example using air heating techniques.

In such a configuration, an exchanger coil can be provided that allows ambient air to pass naturally or by forced circulation, where the working fluid inside the coil is heated and the air outside the coil is cooled.

Structural changes to the circuit in this context are within the skill of skill in the art.

BOG Cycle According to a further aspect of the invention shown in FIG. 7, the seawater circuit can be replaced or added to the BOG circuit.

For such purposes, in particular, a hot water stream 301 is sent to the heat exchanger HE3, where heat exchange occurs with the working fluid.

The flow output 101 from the heat exchanger HE3303 is sent to the heat exchanger HE5 for a heat exchanger with the BOG output from the BOG compressor.

According to a further aspect of the invention (not shown), the heat exchanger between the compressed BOG and the working fluid occurs directly in the heat exchanger HE3.

According to a further aspect of the invention (not shown), BOG compression may be performed in more steps, under this condition, at the output of each compression, heat is generated in more exchangers such as HE3 or a single exchanger. Can be transmitted within (many heat exchanges within a single body).

Electronic Circuits With respect to electrical requirements, the system of the present invention requires approximately 2.25 MW to energetically make the regasification line energetically independent and covers 1/4 of the electrical load of the entire regasification terminal. Requires 4.85 MW.

In particular, the system of the present invention provides all the electrical requirements of 1/4 of the electrical load of the regasification line (2.25 MW) or the entire regasification terminal, low pressure and high pressure cryogenic pumps (PMP1). It is supplied to a boil-off gas compressor (CMP1), and a pump (PMP2) and a boiler circulation pump (PMP3) for pumping seawater.

Accordingly, according to the above description, the present invention describes a regasification line for liquefied natural gas (LNG) comprising:
-Working with the vaporization section of the liquefied natural gas (LNG), and-working fluid, a first heat exchanger (HE1), a compressor, a second exchanger (HE2), a third exchanger (HE3). , And a section of the closed gas cycle, further comprising a turbine for generating electrical energy by said working fluid of the closed gas cycle.

More specifically, the heat of the working fluid of the closed gas cycle is transferred to the liquefied natural gas (LNG) in the first heat exchanger (HE1).

For the purposes of the present invention, the working fluid of a closed gas cycle is selected from the group comprising air, nitrogen, helium and argon.

According to the present invention, the closed gas cycle operates with a fluid preferably composed of monatomic gas.

Preferably, the working fluid of the closed gas cycle is argon.

According to a preferred embodiment of the invention, the described regasification line comprises two heat exchangers (HE1 and HE2, respectively).

In one aspect of the invention, the second exchanger (HE2) is part of a circuit that works with the first intermediate fluid.

Within the second exchanger (HE2), in particular, heat exchange is performed between the first intermediate fluid and the working fluid in a closed gas cycle to which heat is transferred.

In a preferred embodiment of the invention, within the second exchanger (HE2), the first intermediate fluid consists of an endothermic engine, gas turbine or internal combustion engine exhaust evaporative air or process recovery (high temperature source).

According to a further aspect, the regasification line of the present invention comprises a third heat exchanger (HE3).

Such a third exchanger (HE3) is, in particular, part of a circuit that works with a second intermediate fluid.

In particular, in the third heat exchanger (HE3), heat exchange is performed between the second intermediate fluid and the working fluid of the closed gas cycle to which heat is transferred.

For the purposes of the present invention, the working fluid circuit may be integrated with a first intermediate fluid circuit, a second intermediate fluid circuit, or both circuits.

In any case, according to the preferred embodiment of the present invention, the circuit operating with the first intermediate fluid and the circuit operating with the second intermediate fluid are at a low temperature of, for example, a temperature lower than 180 ° C, preferably a temperature lower than 120 ° C. It is a circuit that uses a heat source.

Further, according to a preferred embodiment of the present invention, the circuit operating with the first intermediate fluid and the circuit operating with the second intermediate fluid have a temperature higher than, for example, 180 ° C, preferably higher than 300 ° C, and even more preferably. It is a circuit that utilizes heat sources of high temperature and low temperature higher than 400 ° C.

For the purposes of the present invention, the term "cold heat source" is intended to mean, for example, ambient air, seawater, solar heating, process heat recovery and / or low temperature machinery.

For the purposes of the present invention, the term "high temperature heat source" means, for example, solar heating, waste heat of thermal power cycle, gas turbine or internal combustion engine waste, process heat recovery and / or high temperature machinery. It is intended.

According to a preferred embodiment of the invention, the first intermediate fluid is heated / superheated water or diathermy oil, each circuit being a boiler circuit.

Therefore, cooling of the superheated boiler water or diathermy oil and heating of the working fluid of the closed gas cycle are carried out in the second exchanger (HE2).

According to a particular embodiment, cooling of the boiler water and heating of the working fluid of the closed gas cycle output from the third heat exchanger (HE3) are carried out in the second heat exchanger (HE2) ( 4 and 1).

However, according to an alternative embodiment, in the second heat exchanger, the boiler water is cooled and the first heat exchanger is used to regas the liquefied natural gas (LNG) with the working fluid (HE2). The working fluid of the closed gas cycle output from (HE1) is heated (FIG. 3).

According to a preferred embodiment of the present invention, the second intermediate fluid is seawater, and each circuit is a seawater circuit.

According to the present invention, the regasification line comprises a vaporization section of liquefied natural gas of the submersible combustion vaporizer (SCV) type.

According to a particularly preferred embodiment of the present invention, a closed gas cycle turbine may have an output from a second heat exchanger (HE2) or a third heat exchanger (HE3) to generate electrical energy. The working fluid of the closed gas cycle heated at the output from the second heat exchanger (HE2) is supplied.

In one aspect of the invention, the boiler of the boiler circuit is output from a first heat exchanger (HE1) in which heat exchange between the closed gas cycle working fluid and liquefied natural gas (LNG) is mounted. Part of the regasified natural gas will be supplied.

For the purposes of the present invention, the regasification line of liquefied natural gas (LNG) is connected to an electrical energy supply, if available, or to an external network for power generation units such as gas turbines or internal combustion engines. Including further.

According to an alternative embodiment of the invention, the regasification line for liquefied natural gas is modified to further include a heat pump (HP in FIG. 3).

More specifically, such an embodiment specifies that the circuit of the first intermediate fluid is preferably a boiler circuit.

For heat pumps (HP), this preferably comprises:
-A cooling fluid circuit comprising a pump for circulating the cooling fluid at an option, and-a first and second heat exchanger of the heat pump.

In particular, the cooling fluid circuit is preferably operated by a fluid selected from the group comprising, for example, water-glycol and other cooling fluids such as fluids R134a, R32, R143a, R125 and the like.

According to a preferred embodiment of the invention, the cooling fluid operates as follows:
-The first heat exchange in the first heat exchanger of the pump, represented by the evaporator of the heat pump (VPC of FIGS. 3 and 4). As a result, the cooling fluid acquires heat from the first intermediate fluid (HPF1) of the heat pump.
-The second heat exchange in the second heat exchanger of the pump, represented by the condenser of the heat pump (CPC in FIGS. 3 and 4). As a result, the cooling fluid transfers heat from the second intermediate fluid (HPF2) of the heat pump.

For the purposes of the present invention, the first intermediate fluid (HPF1) is represented by seawater (or fresh water as defined above), which is extracted at a temperature of about 9 ° C. and is self-sufficient in the gasification line. It is cooled to about 4 ° C. in the evaporator of the heat pump (VPC) by heat exchange corresponding to about 4.4 MWt considering the rate and 9.8 MWt by one of the electric load of the regasification terminal. To.

Optionally, prior to the use of the heat pump, seawater is subjected to a filtration step to retain substances and organic materials such as algae, mollusks, and inorganic materials such as sand or particulate matter.

In an alternative aspect of the invention, the first intermediate fluid (HPF1) of the heat pump can be represented by ambient air.

For the purposes of the present invention, the second intermediate fluid (HPF2) is hot water, which is 5.1 MWt, in the condenser of the heat pump (CPC), taking into account the self-sufficiency of the regasification line. And heat exchange corresponding to 11.4 MWt by 1/4 of the electric load of the regasification terminal is heated from about 18 ° C to about 23 ° C.

According to a particularly preferred embodiment of the invention, the circuit of the second intermediate fluid (HPF2) is integrated into the liquefied natural gas (LNG) regasification bypass circuit.

In particular, such integration is implemented by a heat exchanger (HE4 in FIG. 3) in which the second intermediate fluid (HPF2) transfers heat to the liquefied natural gas.

According to a preferred embodiment, the liquefied natural gas flow object for heat exchange with the second intermediate fluid (HPF2) is the LNG output from the first heat exchanger (HE1), at least partially regasified. Has been done.

Further, a portion of the regasified liquefied natural gas discharged from the heat exchanger (HE4) may be used to supply the boiler of the boiler circuit.

According to an even more preferred embodiment of the present invention, a portion of the electric power generated by the turbine of the closed gas cycle is supplied to the heat pump, particularly the compressor (CPC) of the heat pump.

According to a second object of the present invention, a method for generating thermal energy and electrical energy is described.

For the purposes of the present invention, such a method also means a method of regasifying a liquefied gas and / or heating (or overheating) the regasified gas.

One such application is, for example, the storage of cold gas.

In particular, such methods include step 1) of operating a closed gas cycle with a working fluid.

Preferably, step 1) includes the following steps:
i) Performing one or more thermal energy acquisition steps with the working fluid of a closed gas cycle,
ii) A step of carrying out an electric energy generation step by the working fluid, and iii) a step of carrying out a thermal energy transfer step from the working fluid to the liquefied fluid of a closed gas cycle.

In one aspect of the invention, such a liquefied fluid is liquefied natural gas (LNG) in a heat exchanger.

For the purposes of the present invention, the working fluid of a closed gas cycle is selected from the group comprising air, nitrogen, helium and argon.

According to the present invention, the closed gas cycle operates with a fluid preferably composed of monatomic gas.

Preferably, the working fluid of the closed gas cycle is argon.

With respect to step ii) for generating electrical energy, this is preferably carried out by a generator (G1) coupled to a closed gas cycle turbine (T2).

Further, such step ii) is performed after step i) to acquire heat and before step iii) to transfer heat energy.

According to a preferred embodiment of the invention, step i) described above for performing one or more heat acquisition steps with a working fluid of a closed gas cycle comprises step A.

According to another aspect of the invention, step i) described above comprises step A'as an alternative to or in addition to step A.

Preferably, one or both of the steps A and A'includes the acquisition of thermal energy from a cold heat source.

Preferably, step A'includes the acquisition of thermal energy from a hot heat source.

As described above, for the purposes of the present invention, the term "cold heat source" is used, for example, ambient air, seawater, cold solar heating, waste heat of the cold heat output cycle, process heat recovery and / or cold machinery. Is intended to mean.

It is understood that the cold source operates at temperatures below about 180 ° C, preferably less than about 120 ° C.

For the purposes of the present invention, the term "hot heat source" refers to, for example, high temperature solar heating, high temperature heat output cycle exhaust heat, gas turbine or internal combustion engine exhaust, process heat recovery and / or high temperature machinery. Intended to mean.

It is understood that the hot source operates at temperatures above 180 ° C, preferably above 300 ° C, and even more preferably above 400 ° C.

In a particularly preferred embodiment of the present invention, step A of acquiring thermal energy from seawater is carried out.

In an alternative embodiment, step A is performed as an alternative to, or in addition to, the acquisition of thermal energy from hot water heated by the BOG after being compressed in the BOG compressor.

In another particularly preferred embodiment of the invention, step A'is carried out by obtaining thermal energy from superheated water, from the diathermy oil of the boiler circuit, or from the evaporative air produced by the boiler.

As described above, step iii) involves transferring heat energy to the liquefied natural gas, which is thus regasified.

Such regasification is carried out specifically in the heat exchanger (HE1), and the working fluid of the closed gas cycle activates the transfer of thermal energy.

In a particular aspect of the invention, the boiler in step A'contains some of the liquefied natural gas regasified in the heat exchanger (HE1) by heat transfer actuated by the working fluid of the closed gas cycle. Be supplied.

The method described above is preferably operated within a regasification line of liquefied natural gas (LNG) modified according to the invention as described above.

According to an alternative embodiment of the invention, the method comprises the following additional steps:
2) Step to operate the heat pump (HP) by the following steps:
a) A step of implementing a first heat exchange between a cooling fluid and a first intermediate fluid (HPF1), wherein the intermediate fluid (HPF1) transfers heat energy to the cooling fluid.
b) A step of activating a second heat exchange between the cooling fluid and the second intermediate fluid (HPF2), wherein the cooling fluid transfers heat energy to the second intermediate fluid (HPF2). , And 3) the step of activating heat exchange between the second intermediate fluid (HPF2) and the liquefied natural gas (LNG).

With reference to step 3), it is preferably operated on a liquefied natural gas stream that is at least partially regasified in the first heat exchanger (HE1).

According to a particularly preferred embodiment of the method of the present invention, the heat pump operated in step 2) is subjected to the electric energy generated in step ii) , particularly the electric energy generated by the generator G1 connected to the turbine T2. Is supplied.

In particular, a pump for circulating the cooling fluid is supplied.

For further purposes, a regasification terminal with one or more regasification lines of liquefied natural gas (LNG) is described.

In particular, each regasification line is the line described above according to the present invention.

The regasification terminal is meant as a plant and usually has a common structure represented by:
-Liquefied natural gas storage tank,
-Compression section with cryogenic pump: Normally this is a low pressure pump (consumes about 400 kW) and a high pressure pump (consumes about 1300 kW) -Boil-off gas compressor (BOG compressor),.
-Connecting to an electrical energy supply, if available, or an external network for a power generation unit such as a gas turbine or internal combustion engine,
-Vaporization section of liquefied gas, eg, by underwater combustion vaporization technology or open rack vaporizer with its air supply circuit and relative compressor.
-At least one with one or more conventional regasification lines and the bypass configuration described above to meet different requirements and allow for good plant flexibility.

In one aspect of the invention, the terminal comprises 2, 3, 4, 5, or 6 lines, preferably 4 lines.

Different regasification lines operate in parallel.

Therefore, such a structure makes it possible to adapt the technique proposed by the present invention to an existing plant (modification).

For the purposes of the present invention, new embodiments of the regasification terminal can include one or more regasification lines with the bypass configuration described above, eg, an SCV type "conventional" vaporization section. Does not include.

For the technical requirements of the plant, it cannot be ruled out that some elements of a single circuit are common to more regasification lines.

In particular, by arranging an independent closed gas cycle for each line, it is possible to change the heat exchange efficiency in each line, which enables a wide range of working flexibility.

Therefore, the possibility of realizing a plant with different regasification lines has the obvious advantage in terms of flexibility, in each regasification line the method of the invention in an independent manner, not simultaneously or simultaneously. It will be possible to operate.

From the above description, one of ordinary skill in the art can understand a number of advantages provided by the present invention.

First of all, the energy advantage is important, achieving 11% and as much as 37% in configurations that provide the use of seawater and heat pumps.

The method described covers the electrical requirements of the gasification line and uses a compression ratio of 2-3, thus limiting the number of stages of the compressor and turbine while working in a low temperature boiler at about 120-180 ° C. It should not be underestimated to be possible.

In addition, when the regasification load is reduced, the flow rate of the circulating working fluid in the closed gas cycle can be regulated by an outer tank operating at an intermediate pressure between pulling in and out of the compressor. Therefore, the closed gas cycle can be adjusted without reducing the efficiency of the system.

The techniques described also allow the closed gas cycle to operate in an energy bypass configuration no matter how it is disconnected due to technical or maintenance issues.

This energy bypass configuration regulates the electrical and thermal loads of the plant without stopping production, utilizes electrical energy from external networks for regasification, or works with the modular system described. It makes it possible to draw energy from other lines under the condition of excessive electrical production (electrical surplus) and avoid the use of external networks.

This energy bypass configuration provides electrical energy to the plant during maintenance and / or mismanagement of conventional regasification lines, thus allowing it to operate at part of the LNG flow rate.

In addition, process parameters make it possible to use structurally simple and readily available equipment that requires, among other things, conventional metallurgy. Therefore, as a whole, it leads to a reduction in the manufacturing cost of the plant.

The working fluid of the closed gas cycle used for the purposes of the present invention is a monatomic gas.

The use of monatomic gas allows the use of simpler turbomachinery compared to those with polyatomic gas, where a simpler machine means a machine with few variable meridian profiles.

In particular, in addition to the advantages of monatomic gas, the use of argon also allows the possibility of utilizing the positive effects of the actual gas near the saturation curve. That is, the compression effect is less than that of a complete gas. Another advantage of argon is that it has a high molecular weight (40 kg / kmol), which has a low enthalpy shift and a low rotational speed due to the possibility that they bind directly to the generator, so there are few steps. And makes it possible to make turbomachines with a small amount of mechanical stress.

It should also be remembered that argon is chemically inert, nonflammable, and ultimately widely available at low cost.

In addition, the use of argon facilitates the design of turbomachinery based on preliminary calculations and its sizing.

This method completely closes the electrical balance of the regasification line, which is part of the power of the entire plant or the entire regasification plant.

On the other hand, for certain technologies, there is no heat output consumption like SCV, the efficiency of the cycle associated with regassing is achieved, and the power for regassing and compared to the total heat inlet of the cycle. In terms of total heat output, it is close to 1, and fuel gas consumption is reduced with an advantage of over 40% (fuel gas savings-FGS = gas cycle consumption-SCV consumption / SCV consumption) and finally. It results in a 40% reduction in CO ₂ emissions.

Compared to open rack vaporizers, the invention presents the present invention even under conditions that would interfere with the use of ORVs, for example, at seawater temperatures below 5 ° C., and even when low LNG flow sizes are not available. , Allows the use of seawater. In addition, it is not necessary to chemically treat the seawater and pump it to overcome the level difference due to the height of the panel, the source of the equipment used is widely available and easy to find. be.

Embodiments that provide the use of ambient air in the heat exchanger HE3 by air heating technology improve the efficiency of the turbine by blowing air cooled by the transfer of heat to the closed gas cycle onto the turbine itself, thus And make it possible to avoid power downgrades.

These advantages are especially important when the ambient temperature is already high (warm countries), even if the gas turbine covers part of the electrical load (eg plant-based load) and is not integrated with the closed gas cycle. Found.

Embodiments that include the use of BOG circuits have the particular advantage of performing BOG precooling prior to entering the BOG recondensator.

In addition, this allows the working fluid to be further heated without the use of fuel.

Also, in the case of polyphase compression, it is also possible to gradually introduce the heat available after each BOG compression step into the closed gas cycle, thus gradually obtaining very efficient heating.

Embodiments of the invention, including the use of heat pumps, provide additional advantages.

First, for closed gas cycles integrated with heat pumps, the benefits of up to 35% (fuel gas savings (FGS) = (gas cycle consumption-SCV consumption) / SCV consumption) Along with this, a reduction in fuel gas consumption can be obtained with respect to SCV technology.

In addition, heat pumps are efficient and represent the heat output transferred to regasify LNG and the (power) output consumed to transfer energy from seawater to the regasified LNG. Coefficient of Performance (COP) -Has a maximum of 15.

In addition, the heat pump acts between a seawater temperature of 3 ° C to 12 ° C (and above) and an outlet temperature from the heat exchanger HE4 at a maximum of 10 ° C. This makes it possible to achieve a very high COP for the heat pump (in such a configuration, the heat pump acts as a chiller).

Undoubtedly, the installation of the heat pump is flexible and it can be placed near the sea or near the regasification plant. As a result of such flexibility, it offers the possibility of optimizing route seawater pipes according to the specificity of the application.

One of ordinary skill in the art can more easily understand how the techniques described above can be applied not only to the construction of new regasification lines or plants, but also to the modification (modification) of existing plants.

The regasification terminal described by the present invention needs to adapt the plant flow to the needs of regasified or stored LNG, in contrast to the needs to adapt the plant operation to any reduction in LNG flow. With obvious management flexibility, it makes it possible to meet some needs, such as the needs of technical requirements associated with routine and special maintenance of one or more lines.

Note that in addition to those described above, the invention is applicable to base loads and small plant tubes.

Although the present invention has specifically described the regasification of liquefied natural gas (LNG), the regasification lines, regasification terminals, and regasification methods described herein are low temperature (about 0 ° C.). Note that it is similarly applicable to the regasification or vaporization of other liquefied fluids stored at less than) or very cold (less than -45 ° C).

For example, the present invention relates to other liquefied gases such as air, nitrogen, hydrocarbon compounds such as alkanes such as propane and butane, or alkenes such as ethylene and propylene, or liquefied natural gas (LNG), hydrogen. It will also find application in regasification or vaporization.

Further, the present invention may be applied using a liquid or solid cryogenic storage as a cold well rather than a regasified fluid (nitrogen, hydrogen and other gases described above).

On the other hand, in another application, it can be used to form gaseous cryogenic reservoirs, liquids or solids.

Claims (20)

A method for generating thermal and electrical energy within a regasification line of liquefied gas.
The regasification line is
A section of the closed gas cycle that works with the working fluid,
A first heat exchanger (HE1) in which the heat of the working fluid is transferred to the liquefied gas for its regasification.
A turbine (T2) for generating an electric current by the working fluid, and
A second heat exchanger (HE2), which is part of the circuit of the first intermediate fluid that transfers heat to the working fluid, and
A third heat exchanger (HE3), which is part of the circuit of the second intermediate fluid that transfers heat to the working fluid, and
Equipped with
The circuit of the first intermediate fluid is a boiler circuit or a circuit operated by the evaporative air generated by the boiler of the boiler circuit.
The second intermediate fluid is seawater or ambient air.
The method is
1) It is a step to operate a closed gas cycle using a working fluid.
The step to operate is
i) One or more steps of acquiring thermal energy by the working fluid, including the step of acquiring thermal energy from seawater or ambient air (step A).
ii) Steps to generate electrical energy using the working fluid of the closed gas cycle,
iii) A step of operating, including a step of transferring heat energy from the working fluid to the liquefied gas in the first heat exchanger (HE1).
Including, how. According to claim 1 , cooling of the boiler water and heating of the working fluid of the closed gas cycle output from the first heat exchanger (HE1) are carried out in the second heat exchanger (HE2). The method described. The first or second claim, wherein the cooling of the boiler water and the heating of the working fluid of the closed gas cycle output from the third heat exchanger (HE3) are carried out in the second heat exchanger. the method of. In the third heat exchanger (HE3), cooling of seawater and heating of the working fluid of the closed gas cycle output from the first heat exchanger (HE1) cause the liquefied gas to be the working fluid. The method according to any one of claims 1 to 3 , which is carried out for regassing. Claims 1 to 4 , wherein the first intermediate fluid from the second heat exchanger (HE2) is sent into the boiler of the boiler circuit for heat exchange with the evaporative air generated by the boiler. The method described in any one. Any one of claims 1 to 5 , wherein the turbine (T2) of the closed gas cycle is supplied with the working fluid of the closed gas cycle heated, which is output from the second heat exchanger (HE2). The method described in one. The method of claim 5 , wherein the turbine (T2) of the closed gas cycle is supplied with the working fluid of the closed gas cycle heated as an output from the boiler of the boiler circuit. A part of the regasified gas output from the first heat exchanger (HE1) in which the boiler circuit is mounted in which heat exchange between the working fluid of the closed gas cycle and the liquefied gas is carried out. The method according to any one of claims 1 to 7 , comprising a boiler to be supplied. A heat pump (HP) is further provided, and the heat pump is
-Cooling fluid circuit and
-The first heat exchanger (CPC) of the heat pump for heat exchange between the cooling fluid and the first intermediate fluid (HPF1) of the heat pump, and the second intermediate fluid (CPC) of the cooling fluid and the heat pump. The second heat exchanger (VPC) of the heat pump for heat exchange with HPF2) and
-Equipped with another heat exchanger (HE4) for heat exchange between the second intermediate fluid (HPF2) and the liquefied gas.
The method further comprises
2) It is a step to operate the heat pump (HP) by the following steps.
a) A step of implementing a first heat exchange between the cooling fluid and the first intermediate fluid (HPF1) of the heat pump, wherein the first intermediate fluid (HPF1) transfers heat to the cooling fluid. Communicate, steps, and
b) A step of performing a second heat exchange between the cooling fluid and the second intermediate fluid (HPF2) of the heat pump, wherein the cooling fluid heats the second intermediate fluid (HPF2). Including, including, stepping, and actuating,
3) A step of implementing heat exchange between the second intermediate fluid (HPF2) and the liquefied gas, and
The method according to any one of claims 1 to 8 , comprising. The method of claim 9 , wherein the heat pump is supplied with electric power generated by a generator (G1) coupled to the turbine (T2) of the closed gas cycle. The second intermediate fluid circuit is added to the BOG circuit, and the BOG circuit includes a heat exchanger ( HE5 ) that causes heat exchange between the seawater and the BOG circuit, claims 1 to 10 . The method according to any one of. The method according to any one of claims 1 to 11 , wherein step i) comprises the step (step A') of acquiring thermal energy from superheated water or diathermy boiler oil as an alternative or addition to step A. .. The method according to claim 9 , wherein the liquefied gas in step 3) is a partially regasified liquefied gas in the first heat exchanger (HE1). The method according to any one of claims 9 to 13 , comprising a step of supplying the electric energy generated in step ii) to a heat pump (HP). The method according to any one of claims 9 to 14 , wherein a part of the regasified gas according to step iii) is supplied to the boiler. The method according to any one of claims 9 to 15 , wherein the working fluid is selected from the group containing argon, nitrogen, helium, and air. Claims 9-16 , wherein the liquefied gas is selected from the group comprising air, alkanes such as nitrogen, propane and butane, hydrocarbon compounds such as alkenes such as ethylene and propylene, or liquefied natural gas (LNG). The method according to any one of. The method according to any one of claims 9 to 17 , for forming a gaseous, liquid, or solid cryogenic storage. Regasification for liquefied gas comprising one or more regasification lines for liquefied gas operating by the method according to any one of claims 1-18 , wherein the regasification lines are parallel. Terminal. The regasification terminal for liquefied gas according to claim 19 , further comprising an underwater combustion vaporizer (SCV) or an open rack vaporizer type vaporization section.

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