Thermal conduit coupling for heat storage apparatus

1,159,136. Pipe joints. COMSTOCK & WESCOTT Inc. 10 Jan., 1967 [7 Nov., 1966], No. 1355/67. Heading F2G. [Also in Division F4] In heat exchange apparatus, wherein a steel pipe 4 carrying water to be heated extends through a steel container 1 containing a heatstorage material of low thermal conductivity 3, such as sodium hydroxide, the pipe is sealingly secured to the wall of the container by a tubular sleeve 5, which surrounds and is spaced from the pipe, and, which is welded at its opposite ends 7 and 8 to the container wall and pipe respectively. As shown, the sleeve extends outside of the container and the annular space between the sleeve and pipe is filled by the low thermal conductivity, heat storage material which acts as an insulator. In a modification, Fig. 2 (not shown), the sleeve extends into the container, the annular space between sleeve and pipe then being filled by atmospheric air or by insulating material such as the insulant 2 around the container. The connecting sleeve arrangement is said to reduce stresses due to thermal expansion and contraction to acceptable levels. The ratio of the length of the sleeve to the diameter of the conduit is more than 1 : 1, and preferably in the range 4 : 1 to 10 : 1. The ratio of the sleeve mean diameter to the sleeve wall thickness should be in the range 7 : 1 to 12 : 1, preferably 9À5 : 1.