Device, plant and method with high level of energy efficiency for storing and use of thermal energy of solar origin

Abstract

A device for storing and releasing heat energy for an electrical power production plant is described. The device has: at least one bed of fluidisable particles, arranged at least partly at receiving surfaces for such radiation; means for feeding a fluidisation gas for the fluidisation of said particles; and heat exchange elements flown through, in use, by an operating fluid and arranged at or in proximity of said bed of fluidisable particles.

1 . A device for storing and releasing heat energy adapted to receive a concentrated solar radiation, the device comprising:
 at least one bed of fluidisable particles, arranged at least partly at receiving surfaces for said solar radiation;   feeding means for feeding a fluidisation gas for fluidisation of said fluidisable particles; and   heat exchange elements flown through, in use, by an operating fluid and arranged at or in proximity of said at least one bed of fluidisable particles,   wherein an overall arrangement is such that, in use, portions of said at least one bed of fluidisable particles are adapted to be selectively moved by the fluidisation gas for storing heat energy received from solar radiation in a heat storing step and for releasing stored heat energy to said heat exchange elements in a heat releasing step, and   wherein the overall arrangement is such to allow an independent activation of the heat storing step and of the heat releasing step.   
     
     
         2 . The device according to  claim 1 , wherein said at least one bed of fluidisable particles comprises:
 a first storing portion, adapted to store heat energy received from concentrated solar radiation and arranged at the receiving surfaces for the solar radiation; and   a second releasing portion, arranged adjacently to said first storing portion and adapted to release heat energy stored by the first storing portion to said heat exchange elements,   
       wherein said first storing portion and said second releasing portion are adapted to carry out, respectively, said heat storing step and said heat releasing step by a respective fluidisation. 
     
     
         3 . The device according to  claim 2 , wherein said first storing portion and said second releasing portion of said at least one bed of fluidisable particles are received within a common containment casing. 
     
     
         4 . The device according to  claim 1 , wherein said heat exchange elements are arranged so as to be in contact with at least part of said at least one bed of fluidisable particles and/or so as to be lapped against, in use, by at least part of said at least one bed when fluidised by said fluidisation gas. 
     
     
         5 . The device according to  claim 1 , wherein said heat exchange elements are tube bundles. 
     
     
         6 . The device according to  claim 1 , further comprising:
 feeding means and combustion means for a safe combustion of a combustible gas within said at least one bed of fluidisable particles or part thereof.   
     
     
         7 . The device according to  claim 6 , wherein said feeding means comprises a compartmentalization adapted to allow a selective and/or differentiated fluidisation of one or more parts of said at least one bed of fluidisation particles by the fluidisation gas and/or a selective and/or differentiated fluidisation of said first storing portion and said second releasing portion of said at least one bed of fluidisation particles or of parts of the latter. 
     
     
         8 . The device according to  claim 1 , wherein said independent activation of the storing and releasing steps is obtained by a separation of circuits of the operating fluid and of the fluidisation gas. 
     
     
         9 . The device according to  claim 1 , further comprising a gas/gas, preferably air/air, heat exchanger wherein the overall arrangement is such that, in use, in said heat exchanger a first cold gas which is the fluidisation gas to be employed for the fluidisation of said at least one bed of fluidisable particles or of said first storing portion and/or said second releasing portion thereof and a second hot gas which is the fluidisation gas outlet from said at least one bed of fluidisable particles or from said first storing portion and/or said second releasing portion thereof are fed. 
     
     
         10 . The device according to  claim 9 , said devices being arranged on a tower structure housing therein said gas/gas heat exchanger. 
     
     
         11 . The device according to  claim 1 , wherein the fluidisation gas is air. 
     
     
         12 . The device according to  claim 1 , further comprising circulation means for a forced circulation of the fluidisation gas. 
     
     
         13 . The device according to  claim 1 , further comprising means adapted to selectively vary a velocity of the fluidisation gas. 
     
     
         14 . The device according to  claim 1 , further comprising dedusting means for dedusting the fluidisation gas, the dedusting means arranged downstream of a fluidisation zone of said at least one bed of fluidisable particles. 
     
     
         15 . A plant for producing steam or heat for industrial uses, comprising one or more of the devices according to  claim 1 . 
     
     
         16 . The plant according to  claim 15 , wherein the plant is an electrical power production plant. 
     
     
         17 . A method for producing steam or heat for industrial uses from a concentrated solar radiation, providing employ of a bed of fluidisable particles adapted to store heat energy of solar origin and selectively movable by a fluidisation gas, which method comprises:
 storing heat energy, in a storing step received from the concentrated solar radiation by moving of a first portion of said bed of fluidisable particles; and   releasing heat energy, in a releasing step stored in said storing step to heat exchange elements flown through by an operating fluid,   wherein in said storing and releasing steps, heat can be independently activated from each other.   
     
     
         18 . The method according to  claim 17 , wherein said independent activation of the storing and releasing steps is attained by a thermal separation of circuits of the operating fluid and of the fluidisation gas. 
     
     
         19 . The method according to  claim 17 , further comprising:
 providing a step of gas/gas, preferably air/air, heat exchange between a first cold gas which is the fluidisation gas to be employed for the fluidisation of portions of said bed of fluidisation particles and a second hot gas which is the fluidisation gas outlet from said portions of said bed of fluidisation particles.   
     
     
         20 . The method according to  claim 17 , wherein said fluidisation gas is air. 
     
     
         21 . The method according to  claim 17 , wherein a selective variation of a velocity of the fluidisation gas is provided. 
     
     
         22 . The method according to  claim 17 , wherein the method is used for producing electrical power. 
     
     
         23 . The method according to  claim 17 , further comprising providing a combustion of gaseous fossil fuel within said bed of fluidisable particles or parts thereof.