Receiver pipe

Abstract

A receiver tube ( 1 ) for a solar trough collector which focuses the solar radiation incident thereon towards a focal line includes an absorber tube ( 2 ) which in the mounted condition of the receiver tube ( 1 ) extends on the focal line of the trough collector and which is in the form of part of a flow path for a heat carrier medium, and a gas-tightly closed casing tube, in the internal space ( 8 ) of which the absorber tube extends, wherein the flow path for the heat carrier medium is passed outwardly through the wall of the casing tube in the end regions thereof. It is provided that the casing tube includes at least two case portions ( 4, 5 ) which in the mounted condition extend in the direction of the focal line and are gas-tightly connected together along generatrices, the first case portion ( 4 ) comprises a material which is transmissive for the solar radiation, the second case portion ( 5 ) comprises a fracture-resistant material, and the flow path for the heat carrier medium is passed outwardly through a part of the wall of the casing tube, that is not formed by the first case portion.

1 . A receiver tube ( 1 ) for a solar trough collector which focuses the solar radiation incident thereon towards a focal line, wherein the receiver tube ( 1 ) comprises:
 an absorber tube ( 2 ) which in the mounted condition of the receiver tube ( 1 ) extends on the focal line of the trough collector and which is in the form of part of a flow path for a heat carrier medium, and   a gas-tightly closed casing tube, in the internal space ( 8 ) of which the absorber tube ( 2 ) extends, wherein the flow path for the heat carrier medium is passed outwardly through the wall of the casing tube in the end regions thereof,   
       wherein
 the casing tube includes at least two case portions ( 4 ,  5 ) which in the mounted condition of the receiver tube ( 1 ) extend in the direction of the focal line and are gas-tightly connected together along generatrices, 
 the first case portion ( 4 ) which in the mounted condition is towards the trough collector comprises a material which is transmissive for the solar radiation, 
 the second case portion ( 5 ) comprises a fracture-resistant material, and 
 the flow path for the heat carrier medium is passed outwardly through a part of the wall of the casing tube, that is not formed by the first case portion ( 4 ). 
 
     
     
         2 . A receiver tube as set forth in  claim 1  wherein the two case portions ( 4 ,  5 ) extend over the entire length of the receiver tube ( 1 ). 
     
     
         3 . A receiver tube as set forth in  claim 2  wherein the second case portion ( 5 ) is so shaped that it reflects at least parts of the solar radiation incident on its inside onto the absorber tube ( 2 ). 
     
     
         4 . A receiver tube as set forth in  claim 3  wherein the second case portion ( 5 ) on its inside towards the absorber tube ( 2 ) has structures ( 33 ) which differ from a smooth surface and which reflect solar radiation incident thereon in such a way that it is deflected towards the absorber tube ( 2 ). 
     
     
         5 . A receiver tube as set forth  claim 4  wherein the structures ( 33 ) differing from a smooth surface are raised structures ( 33 ) which are directed radially towards the absorber tube ( 2 ) and which are formed by fins which extend in the longitudinal direction of the receiver tube ( 1 ) and which are so mounted at the inside wall of the case portion ( 5 ) that they project in the radial direction towards the absorber tube ( 2 ). 
     
     
         6 . A receiver tube as set forth in  claim 1  wherein at each of its two axial ends the casing tube is closed by an end wall ( 6 ,  7 ) extending substantially perpendicularly to the axis of the receiver tube ( 1 ). 
     
     
         7 . A receiver tube as set forth in  claim 6  wherein the end walls ( 6 ,  7 ) comprise the same material as the second case portion ( 5 ). 
     
     
         8 . A receiver tube as set forth in  claim 1  wherein it includes two thermally insulatedly mounted through-flow pipe connections ( 12 ,  13 ;  17 ,  18 ) for passing the flow path for the heat carrier medium through the wall of the casing tube. 
     
     
         9 . A receiver tube as set forth in  claim 8  wherein the through-flow pipe connections ( 12 ,  13 ) extend through the end walls ( 6 ,  7 ) coaxially with respect to the absorber tube ( 2 ) and are respectively connected to the absorber tube ( 2 ) by a compensating element ( 15 ,  16 ) providing for compensation of different changes in length of the casing tube and the absorber tube ( 2 ). 
     
     
         10 . A receiver tube as set forth in  claim 8  wherein the through-flow pipe connections ( 17 ,  18 ) extend through the second case portion ( 5 ) of the casing tube transversely relative to the longitudinal extent of the absorber tube ( 2 ) and are connected to the axially extending part of the absorber tube ( 2 ) by pipe bends ( 23 ,  24 ) so bent that they provide for compensation of different changes in length of the casing tube and the absorber tube ( 2 ). 
     
     
         11 . A receiver tube as set forth in  claim 1  wherein it includes a valve arrangement ( 30 ,  31 ) which extends