Compact power plant

Abstract

A power plant for energy production from a liquid gas product stored in a cryogenic storage tank, and comprises a container housing and an inlet to receive the gas product from the tank via a line. An evaporation unit converts the liquid gas product to a gaseous phase. The plant comprises an aggregate for the combustion of the gaseous phase to provide an electrical current to an external consumer. A circuit brings the liquid and/or gaseous phase to the motor via the evaporation unit. A regulating unit regulates the pressure and/or temperature. The liquid gas product is supplied to the motor in the gaseous phase by passive liquid and gas transport. A cooling circuit transfers heat from the motor to a heat exchanger in the evaporation unit.

Claims

1. A system for energy production from a liquid gas product, the system comprising: a cryogenic storage tank including an LNG container for storing the liquid gas product; and a power plant, the power plant comprising: a housing comprising an ISO intermodal freight container configured for loading onto a standard freight vehicle; a fuel inlet, provided in or on the housing, to receive the liquid gas product via a line connected to the cryogenic storage tank; an evaporation unit, provided in or on the housing, for converting the liquid gas product to a gaseous phase; an aggregate, provided in the housing, comprising a motor for combustion of the gaseous phase and an electrical generator coupled to the motor such that the electrical generator can be driven by the motor; a line circuit to bring the liquid gas product and/or the gaseous phase from the fuel inlet to the motor via the evaporation unit; a current output to supply an electrical current generated by the electrical generator to a power consumer; a cooling circuit to, in operation, withdraw heat from the motor, where the evaporation unit comprises a heat exchanger to transfer the heat from the motor in the cooling circuit to the liquid gas product to evaporate the liquid gas product; wherein the evaporation unit comprises an ambient heat exchanger provided parallel to the heat exchanger; and a regulating unit, wherein the regulating unit is adapted to regulate a pressure and temperature in the line circuit using at least one valve in the line circuit, such that the pressure of the gaseous phase supplied to the motor is regulated in a predetermined range and such that the temperature of the gaseous phase supplied to the motor amounts to at least 5° C., wherein the regulating unit comprises a passive flow control device to control or influence a flow rate of the liquid gas product to regulate a supply of the liquid gas product, solely driven by the liquid gas product being forced into the evaporation unit via the fuel inlet and the line circuit by an overpressure in the cryogenic storage tank, to the motor in the gaseous phase by passive liquid and gas transport of the liquid gas product and the gaseous phase; wherein the cryogenic storage tank is independently movable from the power plant.

2. The system according to claim 1, wherein the regulating unit is adapted to regulate a temperature of a cooling fluid in the cooling circuit such that said temperature lies in a range of 40° C. to 50° C. before the heat transfer to the liquid gas product in the evaporation unit.

3. The system according to claim 1, wherein the liquid gas product comprises liquefied natural gas.

4. The system according to claim 1, wherein the fuel inlet is adapted to receive the liquid gas product at the overpressure of at least 1.0 barg.

5. The system according to claim 1, wherein the aggregate is adapted to supply an electrical power in a range of 250 kW to 5 MW.

6. The system according to claim 1, further comprising a coupling to connect an external heating circuit and/or an external cooling circuit to the power plant, wherein either the cooling circuit is adapted to transfer the heat to the external heating circuit or wherein the evaporation unit comprises a further heat exchanger to cool a cooling medium in the external cooling circuit by heat transfer from the cooling medium to the liquid gas product, or a combination thereof.

7. The system according to claim 1, comprising a connection to couple a gas distribution network to the line circuit as alternative gas source.

8. The system according to claim 1, wherein the regulating unit regulates the temperature of the gaseous phase such that the temperature at least amounts to 10° C. when supplied to the motor, and wherein the regulating unit regulates the temperature of the gaseous phase such that the temperature amounts to a maximum of 50° C.

9. The system according to claim 1, further comprising a buffer tank coupled to the line circuit.

10. The system according to claim 1, further comprising an electronic control device for processing signals of sensors, for driving actuators and/or for driving the aggregate.

11. A method for energy production from the system of claim 1, the method comprising: providing the power plant to a site by transporting the ISO intermodal freight container to the site; providing the cryogenic storage tank filled with the liquid gas product to the site by transporting the LNG container to the site; connecting the cryogenic storage tank to the fuel inlet of the power plant with the line; evaporating, in the evaporation unit, the liquid gas product that, by the overpressure in the cryogenic storage tank, is forced into the evaporation unit via the fuel inlet and the line circuit, such that the gaseous phase of the liquid gas product is formed; burning the gaseous phase to drive the motor; generating an electrical current by the electrical generator coupled to the motor, and supplying the electrical current via the current output to an external power consumer, wherein the pressure and temperature in the line circuit is regulated in the predetermined range such that the temperature of the gaseous phase amounts to at least 5° C., wherein the liquid gas product in the gaseous phase is supplied to the motor.

12. The system according to claim 10, the electronic control device further comprising a battery to provide a power supply to the electronic control device of the power plant when the aggregate does not supply electrical power.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows a schematic representation of an exemplary power plant according to embodiments of the present invention.

(2) FIG. 2 represents a build-up of a power plant and a removable cryogenic gas storage tank according to embodiments of the present invention in two individually transportable units.

(3) FIG. 3 shows an exemplary diagram of a power plant according to embodiments of the present invention.

(4) FIG. 4 illustrates essential and/or optional characteristics of a method according to embodiments of the present invention.

(5) The drawings are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. Any reference signs in the claims shall not be construed as limiting the scope. In the different drawings, the same reference signs refer to the same or analogous elements.

DETAILED DESCRIPTION OF EMBODIMENTS

(6) The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims.

(7) Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

(8) Similarly it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

(9) Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

(10) Furthermore, the terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

(11) Moreover, the terms top, bottom, above, front and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

(12) It is to be noticed that the term “comprising”, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression “a device comprising means A and B” should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

(13) In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

(14) In a first aspect, the present invention provides a power plant for energy production from a liquid gas product stored in a removable cryogenic storage tank. The power plant comprises a housing in the form of a container that is suitable for transporting the power plant integrally as a transport unit. The power plant comprises a gas inlet, provided in or on the housing, to receive the liquid gas product via a line connected to the removable cryogenic storage tank. The power plant comprises an evaporation unit, in or on the housing, for converting the liquid gas product to a gaseous phase. The power plant comprises an aggregate, provided in the housing. The aggregate comprises a motor for the combustion of the gaseous phase and an electrical generator coupled to the motor such that the electrical generator can be driven by the motor. The power plant comprises a line circuit to bring the liquid gas product and/or the gaseous phase of the gas inlet to the motor via the evaporation unit. The power plant comprises a current output to supply an electrical current generated by the electrical generator to an external power consumer. The power plant also comprises a regulating unit. The regulating unit is adapted to regulate, e.g. control, the pressure and/or temperature in the line circuit using at least one valve in the line circuit, such that the pressure of the gaseous phase supplied to the motor is regulated, e.g. controlled, in a predetermined range and the temperature of the gaseous phase amounts to at least 5° C. The gas inlet, the line circuit, the evaporation unit and the regulating unit are adapted to supply the liquid gas product, when this forced into the evaporation unit via the gas inlet and the line circuit by an overpressure in the cryogenic storage tank, to the motor in the gaseous phase by passive liquid and gas transport of the liquid gas product and the gaseous phase, for example without active liquid transport of the liquid gas product and without active gas transport of the gaseous phase.

(15) FIG. 1 shows a schematic representation of a power plant 1 according to embodiments of the present invention for energy production from a liquid gas product stored in a removable cryogenic storage tank 2.

(16) The liquid gas product may comprise liquefied natural gas, stored in the removable cryogenic storage tank. The cryogenic storage tank 2 may, for example, comprise an ISO LNG container, for example such as schematically illustrated in FIG. 2. Removable cryogenic storage tanks are known in the art. For example, U.S. Pat. No. 6,047,747 discloses a container for the distribution of liquefied natural gas under pressure over land using a freight vehicle. Embodiments according to the present invention may, without being restricted hereto, comprise the movable cryogenic storage tank.

(17) Said power plant 1 comprises a housing 4 in the form of a container that is suitable for transporting the power plant integrally as a transport unit. The container can be an intermodal freight container of a standard size, such as an ISO container, for example a standard 20 ft container, 30 ft container or 40 ft container. More particularly, said housing 4 may be adapted for loading onto a standard freight vehicle.

(18) FIG. 2 shows an exemplary implementation of a power plant 1 according to embodiments of the present invention. The aggregate 3 and the evaporation unit 7 may be installed within the housing. For example, substantially all components of the power plant 1 may be installed within the housing. The housing may comprise a metal frame to form a beam-shaped housing. The sides of said beam-shaped housing may be partly closed, for example by plates and/or grids. Preferably the bottom and/or the lateral sides are partly open in order to suck air from the environment. Preferably the top and/or the lateral sides are partly open in order to be able to discharge residual heat in the form of hot air and/or to discharge combustion gases.

(19) It is an advantage of embodiments according to the present invention that a power plant can be installed at a site without requiring assembly, for example by only making simple connections to the power plant, which in ready-to-use state can be supplied using a freight vehicle. For example, one or more gas distribution circuits can connect the ready-to-start power plant to the movable cryogenic storage tank and one or more current connections can connect the ready-to-start power plant to one or more electrical power consumers. Optionally, one or more heating circuits and/or cooling circuits can be connected to the ready-to-start power plant. For example, the power plant, having a rated power of, for example, 1 MW, can be installed in a limited time, for example in three hour or less.

(20) It is an advantage of embodiments of the present invention that a power plant can be easily maintained and repaired, with restricted duration of an interruption of the energy supply, for example by replacing the power plant with a substantially identical power plant, while the power plant to be repaired or serviced is removed to a maintenance centre. It is a further advantage that several identical power plants can be simply installed in parallel, for example to increase a power supplied in a straightforward manner depending on an evolving energy requirement and/or to provide redundancy in the energy supply.

(21) A power plant according to embodiments of the present invention may comprise an access security, for example a mechanical security, such as a mechanical lock, and/or an electronic security, such as a monitoring system. The power plant may comprise an alarm system to report unauthorised access, for example physical and/or virtual access, to the power plant, for example using an electronic alarm signal, a visual alarm signal and/or an auditive alarm signal. The alarm system may comprise an emergency stop system to switch the power plant off upon detected unauthorised access.

(22) In a power plant according to embodiments of the present invention, the housing may comprise a self-lifting device to hoist the housing autonomously off and/or onto a freight vehicle. The self-lifting device can form an integral part of the housing.

(23) The self-lifting device can, for example, comprise a plurality of folding and/or extendable support elements to the support housing above the ground. The support elements may comprise lifting jack elements to jack the housing up and down. The support elements can be manually driven and/or be driven by the power plant, for example by the motor, the generator and/or a battery of the power plant.

(24) The power plant 1 comprises a gas inlet 5, installed in or on the housing, to receive the liquid gas product via a line 6 connected to the removable cryogenic storage tank 2. Preferably the gas inlet 5 may be adapted to receive the liquid gas product at an overpressure, for example an overpressure in the range of 1.0 barg to 3 barg. The gas inlet may comprise a regulating valve to regulate the pressure of the incoming liquid gas product. The cryogenic storage tank may be adapted to store the liquid gas product under the slightly increased pressure, or may comprise at least one regulating valve to regulate the pressure of the liquid gas product at an output coupling in a suitable pressure range. It is an advantage that, by providing a slight overpressure, the power plant can be passively supplied with the gas product, and thus need not comprise active transport means such as pumps. It is an advantage of such a passive gas supply that, upon start-up of the power plant, only limited power is required to initiate the energy production.

(25) The power plant comprises an evaporation unit 7 for converting the liquid gas product to a gaseous phase.

(26) The power plant comprises an aggregate 3, provided in the housing, comprising a motor 11 for the combustion of the gaseous phase and an electrical generator 12 coupled to the motor such that the electrical generator can be driven by the motor.

(27) In embodiments according to the present invention, the aggregate 3 may be adapted for supplying electrical power in the range of 250 kW to 5 MW, such as, preferably, in the range of 500 kW to 2 MW.

(28) The power plant may comprise a cooling circuit 10 to withdraw heat, in operation, from the motor. The cooling circuit may comprise a suitable cooling fluid, such as water.

(29) In embodiments according to the present invention, the power plant can also be adapted to provide heat via a heating circuit, such as a hot water circuit or a steam circuit. In embodiments according to the present invention, the power plant can also be adapted to provide cooling via a cooling circuit. For example, the power plant may comprise a coupling to connect an external heating and/or cooling circuit to the power plant. For example, said cooling circuit 10, or another cooling circuit that also withdraws heat from the motor and/or an outlet of the motor, may be adapted to transfer heat to the external heating circuit. For example, said evaporation unit 7 may comprise a heat exchanger to cool a cooling medium in the external cooling circuit by heat transfer from this cooling medium to the liquid gas product.

(30) Said evaporation unit 7 may comprise a heat exchanger to transfer heat from said cooling circuit 10 to the liquid gas product to evaporate the liquid gas product.

(31) The power plant comprises a line circuit 9 to bring the liquid gas product and/or the gaseous phase of the gas inlet to the motor via the evaporation unit. For example, in operation, the line circuit can transport the liquid gas product in substantially liquid phase from the gas inlet to the evaporation unit and transport it in substantially gaseous phase from the evaporation unit to the motor. Preferably the line circuit 9 does not comprise active transport means, such as pumps.

(32) In embodiments according to the present invention, the power plant can also comprise a connection for a gas distribution network to serve as alternative gas source for the liquid gas product in the movable cryogenic storage tank. For example, the power plant may comprise a gas distribution network coupling to receive the gas product directly in gaseous phase. For example, this gas distribution network coupling may be connected to said line circuit 9 between the evaporation unit 7 and the motor 11.

(33) The power plant comprises a current output 8 to supply an electrical current generated by the electrical generator 12 to an external power consumer.

(34) In embodiments according to the present invention, the power plant may be adapted to serve as an emergency power supply, for example to ensure a continuous power supply upon a disruption of a power supply via a power distribution network.

(35) In embodiments according to the present invention, the power plant may be adapted to supply an electrical current outside the net (‘off-grid’), for example to ensure a power supply without requiring a connection to a power distribution network.

(36) In embodiments according to the present invention, the power plant may be adapted to be switched in a hybrid energy network, for example in combination with a photovoltaic system and/or wind energy plant.

(37) The power plant further comprises a regulating or regulation unit 15. Said regulating unit is adapted to regulate the pressure and/or temperature in the line circuit using at least one valve in said line circuit 9, such that the pressure of the gaseous phase supplied to the motor is regulated in a predetermined range and the temperature of the gaseous phase amounts to at least 5° C. Preferably said regulating unit can regulate the temperature of the gaseous phase such that this amounts to at least 10° C. when supplied to the motor. Said regulating unit can regulate the temperature of the gaseous phase such that this amounts to a maximum of, for example, 50° C. The predetermined range can, for example, comprise a range of 10 to 1000 mbar, preferably a range of 20 mbar to 200 mbar, preferably a range of 25 mbar to 100 mbar.

(38) The regulating unit can further be adapted to regulate the temperature of the cooling fluid in said cooling circuit 10, e.g. water in the water circuit, such that this temperature lies in the range from 35° C. to 60° C., for example, preferably lying in the range of 40° C. to 50° C., for example such that this temperature is approximately 45° C., before the heat transfer to the liquid gas product in the evaporation unit. By controlling the cooling fluid (e.g. water) temperature to a low temperature, for example approximately 45° C., the temperature of the gaseous phase can be easily controlled within a suitable range for use by the motor. The line circuit 9 thus does not require complex means to regulate the pressure and temperature of the gas.

(39) The regulating unit may comprise passive control mechanisms, such as mechanical control valves. Said control device may also comprise active control mechanisms, such as a processing unit, sensors, such as pressure and/or temperature sensors, and/or electrically driven valves.

(40) For example, the regulating unit may comprise a pressure regulator DR. When no gas is taken off by the motor, the pressure in the line circuit up to the closed pressure regulator DR can increase until this is substantially equal to the tank pressure as supplied to the entrance of said gas inlet 5. The excess gas or pressure can thus be forced back into the tank. When the motor takes off gas, the pressure decreases and liquid gas product can be forced into the system again, dependent on the pressure difference and thus also directly dependent on the consumption. A higher consumption causes a large pressure difference and thus a faster supply. Such a passive open system has the advantage that ventilating excess production of gas in gaseous phase from the liquid gas product can be avoided.

(41) FIG. 3 shows a schematical flow chart of a power plant 1 corresponding to embodiments of the present invention. Said evaporation unit 7 withdraws heat from the cooling circuit 10 to evaporate the liquid gas product in said line circuit 9. In addition, the evaporation unit 7 can also comprise an ambient heat exchanger 17 to evaporate the liquid gas product by exposure to an ambient temperature, for example by heat exchange with the ambient air. This ambient heat exchanger 17 can be installed parallel to a primary heat exchanger to evaporate the liquid gas product using heat withdrawn from said cooling circuit 10. It is an advantage that in a start-up phase of the power plant, where the motor has not yet reached its operating temperature and/or is not yet started up, for example upon an insufficient pressure of the gaseous phase in said line circuit 9, the ambient heat exchanger 17 can evaporate the liquid gas product passively until a sufficient pressure and temperature of the gaseous phase in said line circuit 9 is built up to start the motor. After the motor has warmed up, the primary heat exchanger can substantially take over the evaporation process, so that a sufficient supply rate can be achieved.

(42) Said power plant 1 may comprise a buffer tank 19 coupled to said line circuit 9. It is an advantage of such a buffer tank 19 that a reserve of the gaseous phase can be stored to accommodate variations in the delivered power and/or to build up a reserve of the gaseous phase, for example by evaporation using the ambient heat exchanger 17, for example such that this reserve is sufficient to start the motor and to allow it to reach its operating temperature.

(43) The power plant 1 may comprise a battery 21, for example to provide a continuous power supply to a control device of the power plant, for example upon the start-up of the power plant. The control device can, for example, comprise a processing unit for processing signals of sensors, for driving actuators, such as control valves, and/or for driving the aggregate. The control device can also be connected to said cryogenic storage tank 2, for example to control the temperature and pressure of the stored liquid gas product.

(44) In a power plant according to embodiments of the present invention, the electronic control device may comprise a communication module to monitor and/or control the power plant via a communication connection, such as a digital communication network and/or a radio signal.

(45) In a second aspect, the present invention relates to a method for energy production from a liquid gas product stored in a movable cryogenic storage tank. The method comprises supplying the power plant according to embodiments of the first aspect of the present invention to a site by integrally transporting the power plant as a transport unit to the site. The method comprises supplying a movable cryogenic storage tank filled with the liquid gas product to the site. The method comprises connecting the movable cryogenic storage tank using a line to the gas inlet of the power plant. The method comprises evaporating, in the evaporation unit, the liquid gas product that is forced into the evaporation unit by an overpressure in the cryogenic storage tank via the gas inlet and the line circuit, such that a gaseous phase of the liquid gas product is formed by evaporation. The method comprises the combustion of the gaseous phase to drive the motor of the power plant, and the generation of an electrical current by the electrical generator coupled to the motor. The method comprises supplying the electrical current via the current output of the power plant to an external power consumer.

(46) The pressure and/or temperature in the line circuit can be regulated in a predetermined range such that the temperature of the gaseous phase amounts to at least 5° C. The liquid gas product in the gaseous phase is here supplied to the motor by passive liquid and gas transport of the liquid gas product and the gaseous phase.

(47) The method may also comprise the withdrawal of heat from the motor by a cooling circuit, and may comprise the transmission of heat from the cooling circuit to the liquid gas product to evaporate the liquid gas product in the evaporation unit,

(48) FIG. 4 shows a conceptual representation of a method according to embodiments of the present invention.

(49) The method may comprise, additionally to the supply 101 of the movable cryogenic storage tank 2 filled with the liquid gas product to the site, the supply 102 of a gaseous gas product under pressure via a gas distribution network.

(50) The method may also comprise the connection 103 of the power plant to a photovoltaic system and/or a wind power station.

(51) The method comprises the supply 104 of the electrical current via the current output of the power plant to an external power consumer.

(52) In addition, the method may comprise the supply 105 of heat and/or cooling, the supply 105 comprising, e.g., an external heating circuit and/or an external cooling circuit.

(53) The foregoing description details certain embodiments of the invention. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the invention may be practiced in many ways. It should be noted that the use of particular terminology when describing certain features or aspects of the invention should not be taken to imply that the terminology is being re-defined herein to be restricted to include any specific characteristics of the features or aspects of the invention with which that terminology is connected.