Solar collector having a multi-tube receiver, thermosolar plants that use said collector and method for operating said plants

Abstract

The invention relates to a solar collector having a multi-tube receiver, to thermosolar plants that use said collector and to a method for operating said plants, where the multi-tube receivers have a primary reflector ( 5 ) formed by two continuous symmetrical parametric curves, a secondary reconcentrator ( 6 ) and a receiver ( 1 ) that includes several connected tubes ( 7 ) with a circular cross-section, the center of gravity of the collector being located very close to the axis of rotation of the collector itself, and the concentration ratio C/Cmax being greater than 0.63, having 100% collection efficiency and having a maximum of two reflections of solar rays ( 8 ). The thermosolar plants that use said multi-tube receivers combine same with cylindrical or trough collectors with a tubular receiver and can be used for the direct generation of steam (with a saturation and overheating zone) or the indirect generation of steam (with the collectors connected in series).

1 . A solar collector with multi-tube receiver wherein it is of the parametric type and has a primary reflector formed by two continuous symmetrical parametric curves, a secondary reconcentrator and a receiver through which the heat carrying fluid circulates, the primary reflector and the secondary reconcentrator being optically designed by following the “The Simultaneous Multiple Surface (SMS)” method created by Miñano, Benitez, et al. and whereby the receiver comprises several metal tubes having a circular cross-section, placed next to one other and parallel and joined to each other, all supported on the same horizontal plane on an insulating thermal base. 
     
     
         2 . A solar collector with multi-tube receiver according to  claim 1 , wherein two sections inclined at the extremities, formed by several parallel tubes, are added to the horizontal plane of the multi-tube receiver, the sections inclined at the extremities having the same inclination in relation to the horizontal plane. 
     
     
         3 . A solar collector with multi-tube receiver according to  claim 1 , wherein two sections inclined at the extremities, which have the same inclination in relation to the horizontal plane, are added to the horizontal plane of the multi-tube receiver, the sections inclined at the extremities being formed by only one tube,  this single tube being located in contact with the farthest tube of the horizontal section; the rest of the inclined plane being formed by a free flap, without tubes. 
     
     
         4 . A solar collector with multi-tube receiver according to  claim 1 , wherein two sections inclined at the extremities, which have the same inclination in relation to the horizontal plane, are added to the horizontal plane of the multi-tube receiver, the sections inclined at the extremities being formed by just one tube located in the middle of each inclined section; the rest of the inclined plane, at both sides of the tube, being formed by two free flaps, without tubes. 
     
     
         5 . A solar collector with multi-tube receiver according to  claim 1 , further comprising inclined transparent covers beginning from the insulating base, which minimize convective losses. 
     
     
         6 . A solar collector with multi-tube receiver according to  claim 1 , wherein the tubes are joined together by welding. 
     
     
         7 . A solar collector with multi-tube receiver according to  claim 6 , further comprising a small flap between the tubes. 
     
     
         8 . A solar collector with multi-tube receiver according to  claim 1 , wherein the tubes are joined together by means of clamps. 
     
     
         9 . A thermosolar plant having solar collectors with multi-tube receivers, according to  claim 1 , whose fluid and working temperature range do not produce a change of state, wherein it is designed following a circuit with several collectors connected in series and combines parametric solar collectors with multi-tube receiver with a series of parabolic trough or parametric collectors with vacuum tubular receiver. 
     
     
         10 . A thermosolar plant having solar collectors with multi-tubular receivers according to  claim 9 , whose fluid and working temperature range do not produce a change of state, wherein the fluid circulating is CO 2 . 
     
     
         11 . A thermosolar plant having solar collectors with multi-tube receivers, according to  claim 1 , for direct steam generation, wherein the plant is designed by dividing the solar field into two parts: one area of the solar field is used for the generation of saturated steam with parametric collectors having multi-tube receiver and the other area of the solar field is used for the generation of superheated steam with parabolic trough collectors with tubular receivers or parametric collectors with vacuum tubular receivers. 
     
     
         12 . A thermosolar plant having solar collectors with multi-tube receivers according to  claim 11 , whose fluid and working temperature range produce a change of state, wherein the fluid circulating is water. 
     
     
         13 . An operating method of the thermosolar plant, described in  claim 9 , wherein fluid at a low temperature is introduced into the first parametric collector with multi-tube receiver and is heated by passing from one collector to the next until it reaches a temperature above 300° C.; after reaching said temperature, the fluid begins to circulate through a series of parabolic trough or parametric collectors with vacuum tubular receiver, a fluid at a temperature above 500° C. being obtained at the outlet of these collectors. 
     
     
         14 . An operating method of the thermosolar plant described in  claim 11 , wherein the collectors working at the saturating field at low temperatures are supplied by the supply water of the circuit at low temperatures and as it circulates through the collectors, the water is heated and passes from one collector to the other, until it reaches the steam saturation temperature of about 300° C. before the saturated steam is sent to the collectors in the overheating field and at the outlet of these collectors, superheated steam at a temperature of above 500° C., is obtained, this steam being sent directly to a turbine for the production of electricity.