Reivindicaciones
1. A receiver (1, 43, 44, 54) with longitudinal mirrors for a solar power plant, based on a balanced expansion and pressure collector or receptacle (24) receiving the radiation from an array of slightly concave mirrors (7) parallel to one another, having a markedly longitudinal geometry, i.e., being much longer than it is wide, which can rotate about their longitudinal axis of symmetry (14), which in turn is the axis serving as support in bearings, which are placed on the pillars (9) which, every certain length interval, are buried in the ground and rigidly support the mentioned bearings, therefore the securing shaft, which furthermore is a rotating shaft (14), is always fixed in that straight line position, each mirror (7) being orientated for reflecting radiation (6) towards at least one longitudinal solar receiver (1,43,44, 54), the longitudinal axis of symmetry thereof located at a height H above the height of the axis of the mirror (5) closest to the receiver (1, 43, 44, 54) as a result of columns or pillars (8) supporting it, with an active face (2) where it receives radiation (6) reflected by the mirrors (7); said receiver having a longitudinal geometry and its greatest length parallel to the longitudinal axes (14) of the mirrors (7), and having a certain angle of inclination transverse to the horizontal, there being a final mirror (32) furthest from the receiver (1, 43, 44, 54), two fields of mirrors (7) being able to be assembled symmetrically with respect to two parallel receivers (1, 43, 44, 54) with active faces (2) arranged opposite one another, each face pointing to a field, particularly in assemblies in which the longitudinal axes follow the local meridian, and being assembled both to the north and to the south of the receiver (1, 43, 44, 54) in cases in which the longitudinal axes (14) of the mirrors (7) are parallel to the local astronomical latitude, in which assemblies there can also be two parallel receivers (1, 43, 44, 54) with active faces (2) arranged opposite one another, each face pointing to a field, and in which the positions and angles are expressed in a coordinate system in the working plane used, which is always normal to the longitudinal assembly axes, which are parallel to one another; and the y-axis of the coordinate system in the working plane being the vertical line (10) passing through the central or mid-point (3) of the segment representing the active face (2) of the receiver (1, 43, 44, 54) in the working plane, and the x-axis (11) being the horizontal line passing through the central point (34) of the segment which, in the working plane, represents the mirror (5) closest to the receiver (1, 43, 44, 54), with a transverse width of the active surface or face (2) of the receiver selected from a value in the order of 1% of the·straight line distance between the central point (35) of the furthest mirror (32) of the field and the central point (3) of the active surface (2) of the receiver (1, 43, 44, 54); selecting the angle of vision of the central point (3) of the receiver (1, 43, 44, 54) from the central point (35) of the furthest mirror (32) in a range of values between 10° and 80°, with an optimal value of 45°, measured on the horizontal of the location;and the inclination of the active face (2) of the receiver (1, 43, 44, 54) being determined in that the segment marking said surface in the working plane is perpendicular to the bisector of the field, said bisector being that of the angle formed with the lines going, respectively, from the central point (3) of the active face (2) of the receiver (1, 43, 44, 54) to the central point (34) of the mirror (5) closest to the receiver, and to the central point (35) of the furthest mirror (32); a group of controllable pumps and valves being arranged which are external to the receiver itself but essential for the operation of the invention to force the heat transfer fluid to follow the required movements through the hydraulic circuits of the receiver; the solar radiation (6) reflected by the different mirrors (7) finally striking a receiver (1, 43, 44, 54) inside of which there are arranged longitudinal tubes (19) through which a heat transfer fluid feeding a thermal application circulates; the active face (2) of the receiver (1, 43, 44, 54) being the actual outer surface of the tubes (19) where the radiation (6) strikes, or the active face (2), where the radiation (6) strikes, being thermally connected with the surface of the tubes (19), which are grouped in at least three separate bundles, transversally, there being a central bundle (20) of longitudinal tubes, and at least two adjacent bundles (21) and (22), one on each side of the central bundle (20), these bundles being able to go in the same receptacle (24) or in adjacent receptacles, but in any case without mixing their heat transfer fluid streams when passing through the receiver (1, 43, 44, 54), the central bundle (20) and adjacent bundles (21) and (22) having longitudinal thermal insulation (23) between one another separating them; and the percentage distribution of the total active surface (2) of the receiver (1, 43, 44, 54) between the central bundle of tubes (20) and the adjacent bundles (21) and (22) being a value selected from the central bundle (20) occupying 99% of the active surface, and the adjacent bundles (21) and (22) occupying the rest; and the central bundle occupying 20%, the adjacent bundles (21) and (22) occupying the rest; giving 50% of the active surface occupied by the central bundle (20) as a distribution reference value and the adjacent bundles (21) and (22) each occupying 25% of the total active surface (2) of the receiver (1, 43, 44, 54) on either side, characterised in that the bundles of longitudinal tubes (19) of the receiver (1, 43, 44, 54) are arranged obliquely to one another, the entire angle through which the radiation arrives being covered by the active surface of the tubes as a result of the covering provided by the bundles, there even being a small area in which a shadow of the end of one bundle is cast on the contiguous bundle, with an extension no greater than half the radius of the tube in the shadow, without there being physical contact between the ends of both bundles, and thermal insulation parts further preventing the passage of convection currents being able to be interposed between them without physical contact with both at the same time if there is filling gas in the receptacle (24) of the receiver. 2. The receiver with longitudinal mirrors for a solar power plant according to the preceding claim, characterised in that in assemblies with two symmetrical receivers (43) and (44) with faces opposite one another, the fluid is received from the pipelines (45) supplying it, relatively cold, from the thermal application and is circulated through the adjacent bundles (46) of the first face, which is the one receiving less radiation intensity; and after that first passage they pass to the adjacent bundles (49) of the other receiver (44) by means of an outer connection (48), through which bundles they circulate, thus ending the pre-heating phase in which values of the peripheral areas (38), (39) of the radiation sent by the field of mirrors (7) and striking the active face (2) of the receiver are harnessed; the fluid from the adjacent bundles (49) of the second receiver (44) then entering into the central bundle (47) of the first receiver (43) through an outer connection (50), where levels of concentrated radiation are higher (37) in intensity, this being measured in watts per unit of surface area, making the fluid acquire higher temperatures as it passes through said bundle, and this greater heating is completed when the fluid passes through the central bundle (52) of the second receiver (44), which it reaches from the central bundle (47) of the first receiver (43), through another outer connection (51), and from which it exits through the outer duct (53) to go to the thermal application.
