EP2405176B1 - Method and device for providing electrical and thermal energy, in particular in a harbour - Google Patents

Description

The invention relates to a method for the provision of electrical and thermal energy, in particular in a port facility, wherein liquefied natural gas (LNG) is stored in a vessel-fillable LNG terminal, from which the resulting boil-off gas is withdrawn and in an internal combustion engine is burned to generate heat and electricity, wherein the heat is passed to heat consumers and the electrical energy is fed or stored in the network and liquid natural gas is evaporated from the LNG terminal and is supplied to a gas supply network, and to a device for carrying out this procedure.

Methods and devices for use and in particular for the conversion of different forms of energy into electrical energy have become known in different embodiments. Especially in hydropower plants and in particular in methods and devices for the use of wind energy, solar energy or tidal energy is often observed that the respective dependent on external conditions generation of electrical energy can not be easily reconciled with the respective needs. Thus, for example, the energy production of solar systems depends on sunlight, with a first peak of energy consumption usually occurs when suddenly after sunset electrical lighting fixtures are turned on.

For the purpose of equalization or smoothing of the electrical output power of such powered with regenerative energy energy converter has already been proposed to store the energy required in times of lower demand accordingly. Although electrical energy can be stored in principle in accumulators. However, the investment required for such storage of electrical energy and the space required make such efforts economically unreasonable. The consideration of location-related weather conditions by a Blade angle adjustment of the rotor blades of a wind turbine is not suitable to make sensible use of the maximum amount of electrical energy that can be generated. Rather, by such measures on the production of electrical energy in times of lower demand waived, although the existing wind energy would favor such production. In order to be able to better compensate for fluctuations between power generation and energy consumption, it is known in principle to use storage media, wherein as mechanical storage, for example, flywheel energy storage come into consideration. Superconducting magnetic energy storage devices, battery storage systems and hydrogen-based chemical energy storage devices have also been proposed.

Liquefied natural gas (LNG) is liquefied natural gas by cooling to -164 to -161 ° C (109 K to 112 K). Liquid natural gas is about 1 / 600th of the volume of natural gas in gaseous form.

Liquid natural gas has great advantages, especially for transport and storage purposes. The natural gas loses its characteristic of the line boundness by such a cooling and can thus be transported on the road, the rail and on the water. So far, this type of transport played only a minor role, since in particular for the complicated liquefaction about 10 to 25 percent of the energy content of the gas are needed. If the distances to be bridged between the source of natural gas and the consumer are less than 2,000 kilometers, transport via the natural gas pipeline or as compressed natural gas (CNG) is more economical.

The standard transport route is secured via pipelines from the natural gas production facility to a purpose-built LNG terminal in a port. In the LNG terminal, the previously gaseous natural gas is liquefied to liquid natural gas. These systems are extremely cost and energy intensive. Then the liquid natural gas is pumped onto special ships, They drive to another LNG terminal and transport the liquid natural gas back to shore using the ship's own cargo pumps. The ever-expanding ships are also referred to as 2G tankers. The onward transport usually takes place after a conversion into the gaseous state by pipelines to the remote gas companies, predominantly to a hub.

In 2004, about five percent of natural gas transports were carried out worldwide in the form of liquefied natural gas. Due to the currently high gas prices and the expected further increases in the course of price maintenance of crude oil, however, this transport option for natural gas is becoming increasingly important. Currently, more than 25 percent of the natural gas transported worldwide is transported as liquid natural gas with an upward trend.

Despite the isolation of the LNG tankers, the slow heating of the tanks leads to the evaporation of a part of the charge, the so-called "boil-off". So that the pressure in the tank does not assume inadmissibly high values, the vaporized gas must be able to escape. Instead of a blow-off, this gas is used for generating steam and finally for propulsion and power generation. For this reason, LNG tankers are predominantly designed as turbine ships for heavy oil and / or natural gas operation. Excess production of boil-off gas causes overproduction of steam in the auxiliary or main condenser to be condensed into seawater, so that in no normal marine operation, methane (as the main natural gas constituent) must be vented to the atmosphere. Exceeding these capacitance limits of the capacitors, the boil-off gas is blown into the atmosphere through a mast or reliquefied with in-vessel condensers to maintain tank pressure within the allowable range.

In the document KR20090072042 is described a method for providing electrical and thermal energy, wherein liquefied natural gas is stored in an LNG tank from which the resulting boil-off gas is withdrawn and burned in an internal combustion engine to generate heat and electricity.

The document US-A-4,995,234 describes a process in which liquefied natural gas is evaporated from an LNG terminal and fed to a gas supply network. The withdrawn from the LNG terminal liquid natural gas is first compressed and then fed to an evaporator and then expanded via a turbine to feed pressure of the gas supply network, the cold obtained from the evaporation and relaxation is supplied to cold consumers.

The invention now aims to provide a method and a device, with which a maximum of available liquefaction energy and caloric energy from the (liquid) Natural gas can be recovered, so that overall a more economical device or a more economical process is created.

To solve this problem, the inventive method is carried out such that the liquid natural gas is compressed after evaporation and is then expanded via a turbine to feed pressure of the gas supply network, the recovered cold from the evaporation and relaxation is supplied to cold consumers and the relaxing of the Gas via the turbine obtained electrical energy is fed or stored in the network. Since port facilities always require refrigeration, especially for refrigerated warehouses for storing food or freshly caught fish, the cold obtained by these process steps can be used simply and economically. So far, the cold produced by regasification has always been seen as a waste product in this environment and simply released into the atmosphere. By using this energy, the economics of the process can be increased. The fact that the gas is compressed after regasification via the feed pressure of a gas supply network, the gas must not be pressed by large pumps in the gas supply network, but can be expanded by a turbine, so here additional electrical and thermal energy is released, which will continue to be used can.

For regasification and compression of the natural gas, a cyclic, piston-less process is preferably used, as described, for example, in US Pat W02007 / 128023 is described. For this purpose, the procedure is preferably such that the liquid natural gas is spent for vaporizing and compressing in a dosing and a metered amount is fed to an evaporator, whereupon the dosing is again filled with liquid gas and the pressure in the last used evaporator for squeezing the liquid Gas is used from the dosing into another evaporator, wherein each cyclically Vaporizers different from each other are charged from the dosing and the pressure in the dosing and, if necessary, in each case to be filled evaporator is reduced before a renewed introduction of a metered amount of the liquefied gas and the gas is then expanded via a turbine to feed pressure of a gas network. As a result, no expensive and wear-prone pumps are necessary, so that the process causes less costs during operation.

In order to be able to provide more cold, preference is given to using a biogas plant with connected cryogenic gas purification and liquefaction for recycling organic waste, the biogas produced being burned in an internal combustion engine generating heat and electricity, the heat being passed on to heat consumers and the electrical energy is stored and the cold used in the biogas plant is recovered and the cold is supplied to refrigeration consumers. In such biogas plants in particular CO _{2 is produced} as starting material for dry ice, which is also easy to transport within the port facility for cooling purposes. Such a method is, for example, in the Austrian patent application AT508249 shown and described.

In order to meet the great demand for electric power in the port facility, the method is preferably carried out such that in addition a renewable energy power plant, such as tidal power plant, wind power plant, hydropower plant, etc. is used to provide additional electrical energy.

In order to store the electrical energy of the individual producers, it is preferable to liquefy a gas in a device which is coupled to an electrical energy generating device, that the liquefied gas is preferably stored without pressure and that the liquefied gas can be used as needed, preferably with the aid of a refrigeration cycle of a refrigeration consumer, regasified and the energy released is converted into electrical energy and either fed into the grid or made available to electrical consumers. A particularly efficient method based on this principle is in the Austrian patent AT506779 described.

The liquid natural gas is stored in the LNG terminal preferably in an atmospheric tank. The fact that the tank is only isolated, but not actively cooled, falls through the heat input through the insulation at any time uniform boil-off gas, which is burned in the internal combustion engine, with 33% of the energy is converted into electrical energy on average and 67% in caloric heat. This electrical energy can be used immediately to supply the needs of the port facility, or also be kept in stock in the form of the liquefied gas for times of increased demand. Should a total of more electrical energy be generated than is consumed, this energy can also be sold by feeding it into the electricity network to energy providers. However, liquid natural gas may also be taken from the atmospheric tank, if necessary, and transported on the road, rail or water.

The inventive device for providing electrical and thermal energy in a port facility, wherein the liquid natural gas is stored in an LNG terminal in an atmospheric tank, which is followed by an internal combustion engine for burning the boil-off gas and the internal combustion engine, an energy storage for electrical energy is connected, wherein the internal combustion engine is connected via a heat conductor with heat consumers and the atmospheric tank is followed by an evaporator for evaporating the liquid natural gas, wherein the evaporator is followed by a turbine for generating electricity, according to the invention further developed such that the evaporation or expansion cooling can be transported via heat conductors to refrigeration consumers.

Characterized in that preferably at least two evaporators downstream of the atmospheric tank with the interposition of a dosing, the above-mentioned method for cyclic, piston-less compression can be performed, which is characterized in particular by its efficiency and robustness.

Characterized in that the internal combustion engine is preceded by a biogas plant with cryogenic gas purification and gas liquefaction for recycling organic waste, wherein the biogas produced is supplied via lines of the internal combustion engine for generating heat and electricity, wherein the heat is forwarded via heat conductors to heat consumers and stored the electrical energy is and the obtained in the biogas plant refrigeration cold consumers supplied, more cold, which is usually obtained in the biogas plant as dry ice and therefore easy to transport, can be obtained for cooling purposes.

There may be other power plants serve to meet the electrical needs of the port facility, which is preferably provided that in addition a power plant for renewable energy, such as tidal power plant, wind power plant, hydroelectric power station, etc. upstream of the energy storage to provide the electrical energy.

For storing the electrical energy, the device is preferably further developed in such a way that a gas liquefying device coupled to an electrical energy device empties a storage tank for storing the liquefied gas, a regasification device connected to the storage tank for regasifying the liquefied gas, an expansion machine, in particular a turbine of the regasified gas and one of the expansion engine having driven electric generator, wherein the electric power supplied by the generator is provided to electrical consumers.

The invention will be explained in more detail below an embodiment schematically illustrated in the drawing. In this shows Fig.1 a device for storing energy in an embodiment that requires a pump, Fig.2 a device for storing energy in an embodiment in which the gas is compressed without a piston and cyclically without the use of a pump, Figure 3 a pH diagram of the working medium and Figure 4 a schematic harbor facility.

In the drawing, 1 denotes a wind generator, wherein the electrical energy generated by the generator can be fed via the electrical line 2 into the network. As soon as the demand for electrical energy, which is fed via the line 2 into the network, below the energy generated in each case, 3 of an air liquefaction 4 can be supplied via an electrical line, the liquefied air enters a cryogenic tank 5. For regasification, the liquefied air stored without pressure is supplied via a line 6 to an evaporator 7, wherein the volume increase during the evaporation of a corresponding compressed gas via line 8 is supplied to a buffer 9 to equalize the pressure and is passed through a turbine 10, which with a generator 11 is coupled. The electrical energy generated in the generator 11 can in turn be fed via the line 12 into the network, if in addition and possibly the production of the wind power plant 1 exceeding demand indicators are determined, so that in addition to the fed via the line 2 in the network current over the Line 12 power can be fed into the grid. In a separator 13, the liquid gas components are separated and the liquid phase returned to the tank and the gas phase to the condenser. For this purpose and for the purpose of pressing liquid gas into the evaporator, a pump 14 is necessary.

In Fig. 2 an embodiment is shown in which no pump 14 is necessary. The remaining reference numerals have been retained. Here, the liquid gas enters a dosing 15, which subsequently alternately fed the two downstream evaporators 7 and 7 '. In the evaporators 7, 7 ', the air is superheated to 70 bar and is supercritical at temperatures which are far below the ambient temperature. The respective temperatures are on a pH diagram to the right of the critical point. Based on this state is subsequently relaxed to 40 bar via the turbine 10, which is coupled to the generator 11, so that via the line 12 power can be released into the power grid. By relaxation, the temperature drops, for better use of this energy, the exhaust air flow through the evaporator 7, 7 'is passed, which serves as a cooler. The cooling takes place with liquid air, which is caused by the throttling process in the separator 13 and the air liquefaction plant 4. Due to the pressure difference, the gas flows after the turbine 10 into the respective other evaporator 7 ', 7, wherein the supercritical air is further cooled and a state point is reached to the left of the critical point on the pH diagram.

The metering container 15 is thereby via the line 16 in the separator 13 to tank pressure, which is at 1-2 bar, relaxed, the liquid phase to the tank and the gas phase is supplied to the condenser again. This time, no pump 14 is necessary, since the gas phase is sucked in by the air liquefaction plant 4. This is the prerequisite for a further filling of the dosing. Likewise, the supercritical air after cooling via the turbine from the evaporator 7, 7 ', throttled via the separator 13. The resulting gas is passed into the air liquefaction plant 4 and the resulting lack in the liquid phase is from the cryogenic tank 5, in which liquefied gas is in stock, which tank is fed by the air liquefaction plant refilled. From the separator 13 can be filled with liquid gas via the line 17 and the dosing again.

Because the air expanded via the turbine is returned to the evaporators 7, 7 'as cooling, the greatest temperature difference prevails there.

Fig. 3 shows a pH diagram of the working gas. In the evaporator 7, 7 ', the gas is superheated to 100 bar and is supercritical right of the critical point 18 at the point 19, wherein the temperature is far below the ambient temperature. In the next step, the gas is expanded via the turbine 13 to 40 bar and reaches the point 20 with simultaneous loss of temperature. The gas is then further cooled by means of liquid air, which originated from the throttling process, and the expanded air through the turbine until a point 21 is reached to the left of the critical point on the pH diagram. During the throttling process in the separator 13, the gas pressure drops to the point 22. When the liquid gas is returned, the temperature of the gas falls, at which point it is at point 23 in the pH diagram, and is then returned to the dosing tank 15.

The re-liquefaction is therefore possible in principle twice in the process. Once in the area of the superheated steam, from point 20 to point 21 in the pH diagram, wherein the temperature difference is very small, but the heat exchange surfaces are very large. Re-liquefaction is possible a second time after cooling with liquid product in the supercritical range. It tries to get as far as possible to the left side of the critical point (point 21), starting from the point 21 in Fig. 3 can be throttled to a pressure close to ambient pressure (item 22). This inevitably eliminates the largest portion of the liquid phase and it creates the smallest proportion of gas. This second throttling makes this process particularly economical.

In the same way, the liquid natural gas is cyclically and piston-less evaporated, compressed and expanded by a turbine in a gas supply network, in which case also the relaxation cold can be utilized in the port facility.

In Figure 4 is an atmospheric tank designated 23, wherein a line 24 is indicated, with which the liquid natural gas can be sucked from transport ships. Via the line 25, the liquid natural gas can be loaded on further means of locomotion. Due to the heat input via the insulation of the atmospheric tank 23, boil-off gas falls in the tank 23, which gas is supplied via a line 26 to an internal combustion engine 27. The resulting heat in the internal combustion engine 27 is passed via a line 28 to heat consumers. The power generated in the internal combustion engine 27 is passed via a line 29 to a transformer 30 and fed from there either into a power grid 31 and sold or used to meet the needs of the port facility. Otherwise, the power may be supplied via a line 32 to the air liquefaction plant 4 to store the energy for times of greater demand. The energy released in the regasification can be returned to the transformer 30 via a line 33.

The liquid natural gas is removed from the tank 23 via a line 34 and subjected to the above-described method of cyclic, piston-less compression, the device required for this is designated 35. The evaporative cooling is supplied via the line 36 to the cold consumers. 37 designates a turbine via which the compressed gas is expanded, wherein here on the one hand the expansion cooling is supplied via a line 38 to the refrigerants consumers and the power generated via the line 39 either the transformer 30 is supplied or the air liquefaction 4. With 43 refers to the line through which the natural gas is fed into the gas network.

With 40 is a biogas plant for the recovery of organic waste called, in this as the final product, for example. Biomethane and CO _{2 is obtained} in the form of dry ice. The biomethane is supplied via the line 41 of the internal combustion engine 27 for combustion. About the line or the path 42, the cold or dry ice is supplied to the cold consumers.

Claims (11)

1. A method for providing electrical and thermal energy, in particular in a harbour installation, wherein liquefied natural gas (LNG) is stored in an LNG terminal that can be filled from ships and from which the forming boil-off gas is withdrawn and burned in an internal combustion engine while generating heat and power, the heat being conveyed to heat consumers and the electrical energy being fed into the mains grid or stored and liquid natural gas from the LNG terminal being evaporated and supplied to a gas supply network, characterized in that the liquid natural gas, after evaporation, is compressed without using a pump and subsequently expanded to the feed-in pressure of the gas supply network via a turbine (10, 37), wherein the cold recovered from evaporation and expansion is supplied to cold consumers and the electrical energy recovered during the expansion of the gas via the turbine (10, 37) is fed into the mains grid or stored.
2. A method according to claim 1, characterized in that the liquid natural gas is passed into a metering vessel (15) for evaporation and compression and a metered amount is supplied to an evaporator, whereupon the metering vessel (15) is refilled with liquid gas and the pressure in the most recently used evaporator (7, 7') is used for pressing the liquid gas out of the metering vessel (15) into a further evaporator (7, 7'), wherein cyclically different evaporators (7, 7') are respectively charged from the metering vessel (15), and the pressure in the metering vessel (15) and, if required, in the respective evaporator (7, 7') to be filled is relieved prior to newly introducing a metered amount of the liquefied gas.
3. A method according to claim 1 or 2, characterized in that a biogas plant (40) with connected cryogenic gas purification and liquefaction is used for processing organic waste, wherein the produced biogas is burned in an internal combustion engine (27) while generating heat and power, the heat being conveyed to heat consumers and the electrical energy being stored, and the cold used in the biogas plant (40) being recovered and supplied to cold consumers.
4. A method according to claim 1, 2 or 3, characterized in that a power plant for renewable energies, such as a tidal power plant, a wind turbine generator system, a hydropower station etc., is additionally used to provide additional electrical energy.
5. A method according to any one of claims 1 to 4, characterized in that a gas is liquefied in a device that is coupled to an electrical energy generating device, that the liquefied gas is preferably stored unpressurized, and that the liquefied gas, if required, is regasified, preferably by using a refrigeration cycle of a cold consumer, and the redundant energy is converted into electrical energy to be either fed into the mains grid or made available to electric consumers.
6. A method according to any one of claims 1 to 5, characterized in that the liquid natural gas is stored in an atmospheric tank (23) in the LNG terminal.
7. A device for providing electrical and thermal energy in a harbour installation, wherein liquid natural gas is stored in an LNG terminal in an atmospheric tank consecutively to which an internal combustion engine for burning the boil-off gas is arranged, and an energy storage for electrical energy is arranged consecutively to the internal combustion engine, wherein the internal combustion engine is connected to heat consumers via a heat conductor, and an evaporator for evaporating the liquid natural gas and a device for cyclically compressing the evaporated natural gas in a piston-free manner is arranged consecutively to the atmospheric tank, wherein a turbine for generating power is consecutively arranged to the evaporator, and the evaporation and/or expansion cold can be transported to cold consumers via heat conductors.
8. A device according to claim 7, characterized in that at least two evaporators (7, 7') are arranged consecutively to the atmospheric tank (23) via an interposed metering vessel (15).
9. A device according to claim 7 or 8, characterized in that the internal combustion engine is preceded by a biogas plant (40) with cryogenic gas purification and gas liquefaction for processing organic waste, wherein the produced biogas, via lines, is supplied to the internal combustion engine (27) for generating heat and power, wherein the heat is conveyed to heat consumers via heat conductors and the electrical energy is stored and the cold recovered in the biogas plant (40) is supplied to cold consumers.
10. A device according to claim 7, 8 or 9, characterized in that a power plant for renewable energies, such as a tidal power plant, a wind turbine generator system, a hydropower station etc., precedes the energy storage to provide electrical energy.
11. A device according to claims 7 to 10, characterized in that a gas liquefaction device coupled to an electrical energy generating device comprises a storage vessel for storing the liquefied gas, a regasification plant connected to the storage container for regasifying the liquefied gas, an expansion machine, in particular turbine (10, 37), for expanding the regasified gas, and an electrical generator driven by the
    expansion machine, wherein the electrical energy supplied by the generator is made available to electric consumers.

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