Patent GB-781699-A (GB)
Title: Installations for cleaning, during operation, gas-swept heating surfaces in heat exchange apparatus
IPC: F28G1/16
Filed: 1956-05-30
Abstract: 781,699. Cleaning heat-exchangers. AKTIEBOLAGET, A. EKSTROMS MASKINAFFAR. May 30, 1956 [Nov. 24, 1955], No. 16785/56. Class 99(2). In an installation for cleaning the gasswept heating-surfaces 29 in a heat-exchange apparatus 10 while the latter is in operation and by the use of cleaning elements such as steel pellets which after the distribution thereof over the surfaces 29 are collected in a pocket 11 prior to being recycled to the top of the apparatus for performing a further cleaning cycle, there is provided a vertical or almost vertical and straight conveying conduit 17 extending above the upper level of the apparatus and a feed unit comprising a vertical or almost vertical tube 26 connected to the lower end of the conduit and constituting an inlet for a gaseous pellet-conveying fluid, and a feed pipe 25 opening into and between the ends of the tube 26. There is means for delivering the pellets into the pipe 25 after passage through the apparatus, a pipe 19 connecting the conduit 17 to the top of the apparatus, and a fan 23 for inducing a gaseous flow in the conduit to convey the pellets to the top of the apparatus. As shown, below the pocket 11 is a hopper 12 which is agitated by vibrator means 13 to release the pellets into a shoot 14 opening into a collector 15. The latter communicates with a funnel 16 disposed at the upper end of the inclined or horizontal pipe 25 opening into the tube 26 which is of venturi form and due to the restricted area of the tube in the region of the pipe 25 and the consequent increase in velocity of the gaseous flow the pellets are sucked from the pipe by the air flow induced therein and prevented from dropping downwardly in the tube 26. The flue gases flowing into the apparatus enter a flue 30 and pass through a baffle member 32 into a laterally disposed flue 31. At the top of the conduit is a widened portion 17a provided with a cover 18 of wear-resistant material preferably softer than that of the pellets or provided on the underside thereof with a coating of rubber ; because of the portion 17a the pellets are decelerated due to a reduction in velocity of the gaseous conveying fluid and so the cover 18 is subjected to less violent shocks than would otherwise occur. The pipe 19 which has a replaceable lining of wear-resistant material, delivers the pellets into a separator 20 from which the pellets are released at a desired rate through a control valve 24 and into a conduit 27 below which is a member 28 that scatters the pellets in different directions. The fluid passes through a tube 21 to a collecting receptacle 22a adapted to catch and retain pellets which bypass the separator 20 ; the receptacle is connected by a conduit to the suction fan 23 which is driven by an electric motor 34. In modifications, (a) the pellets are delivered by belt conveyers from the hopper 12 to the collector 15, (b) there is a feed-screw within the pipe 25, (c) a blower fan disposed at the lower end of the tube 26 replaces the suction fan 23, there being a trap device in or adjacent the pipe 25 to prevent pellets being forced back along that pipe, and (d) the top of the conduit 17 is connected to the separator 20 by a bend. Specifications 750,666 and 753,851 are referred to.