GB461779A - Improved apparatus for supplying compressed air to deep-level mines for power and/or cooling purposes - Google Patents

Abstract

461,779. Pneumatic power transmission. WALKER, W. J. March 9, 1936, No. 7125. [Class 8 (ii)] [Also in Group XIII] In apparatus for supplying compressed air to deep levels in mines for power or for cooling purposes, air delivered from a compressor 11, Fig. 1 at the surface is expanded in a motor 13 or otherwise cooled and then led down a conduit 16 to another expansion motor 19 at the deep level, from which a part may be led off through branch pipe 22 for power or cooling purposes while the remainder is led back to the surface compressor by a conduit 18 in heat exchange with the down-flow conduit. Preferably the conduits are concentric, the colder one being inside the warmer one. The surface expansion motor may assist the compressor motor 14 and a heat - exchanger 23 for the return and the compressed air may be provided at the surface. The air may be circulated repeatedly in a closed cycle and cooling may be effected to such a degree that the air is liquefied at the deep levels. It is stated that by suitable adjustment of the work done in the surface and deep level expansion motors the descending air may acquire a pressure gain due to depth greater than the pressure loss in the ascending column. Fresh air may be admitted through a valved branch 10 to the compressor. In the modification shown in Fig. 2, air compressed in a compressor 26, expanded in a surface motor 27 and led to the deep level motor 31 is returned to an auxiliary compressor 34 and motor 35 at the surface and led down again through a third concentric conduit 33. A valved byepass conduit 38 is provided in front of the auxiliary compressor. In a further modification compressed and expanded air is delivered through a descending innermost conduit for use at the deep level and is cooled by a second stream of air circulating in a compression-expansion cycle in heat exchange with the first.