Patent GB-515699-A (GB)
Abstract: 515,699. Boiler &c. cleaners. BABCOCK & WILCOX, Ltd. June 9, 1938, No. 17131. Convention date, July 19, 1937. [Class 99 (ii)] A boiler or other fluid - heater cleaner operating with cleaning fluid under pressure and comprising a blower element adapted to be projected into and retracted from its cleaning position is actuated for retraction from a source of power other than the supply of cleaning fluid, and means, influenced by the cleaning fluid are adapted in the event of failure of the supply of' or a substantial drop in the pressure of the cleaning fluid during the projection of the blower, automatically to effect the connection to the source of power and thereby return the blower to its retracted position. The source of power may also effect the projection of the blower. An aperture 31, Fig. 3, in the wall of a boiler houses a casing 32 to which is bolted a casing 38 housing the blower and connected at its outer end to a housing 41 containing reduction 'gear which operates the blower, the housing 41 being connected to a further casing 40 secured at its outer end to a header . 44. Rigid with the header 44 is an inner tube 62 threaded externally to engage a nut member 61 rotatable thereon and rigidly secured to an octagonal tube 50 extending through the casings 40, 38 and mounted in a ball bearing 51 in the latter. At its outer end, the tube 50 carries, through a ball bearing 58, a second non-rotatable tube 56 threaded on its exterior to receive the threaded end 55 of a second octagonal tube 47 supported at its inner end through a packing 48 by.the tube 50 and carrying the cleaning nozzle 46. Rotation of the tube 50 traverses the tube along the threaded tube 62 and causes the tube 47 to advance along the outer threaded tube 56 carried by the tube 50. To rotate the tube 50 it is slidably secured in a sleeve 66 having an octagonal bore and the sleeve is rigid with a gear wheel 69 meshing with a pinion 70 coupled to a driving shaft 73, the sleeve 66 and gears 69, 70 being mounted in the housing 41. Cleaning fluid is supplied through the header 44 to a pair of telescopic tubes 108, 107 within the tube 62, the pressure of the fluid being thus isolated from the mechanism of the blower. Some fluid however escapes through ports 111 in the inner end of the tube 107 to flow outwards between the tubes 47 and 62, through a port 112 in the latter, and back between the tubes 62 and 50 to cool the mechanism and then to be discharged along the tube 47 to cool its inner end, drainage conduits 119, 116 being provided. The shaft 73 is driven by a motor 65, Fig. 2, controlled by a system including a press-button starting switch 86 an emergency stopping switch 165, a switch 166 for reversing the motor in emergency to retract the blower, and a reversing switch 81 for automatically retracting the blower after it has been projected into the boiler. To actuate the switch 81, the shaft 73 operates a traverse mechanism comprising a long pinion 87, Fig. 12, driving a pinion 88 fixed to a threaded shaft 90 carrying an internally threaded pinion 89 slightly smaller than the pinion 88 and meshing with the long pinion 87. A collar 91 rigid with pinion 89 is engaged by an arm rigid with a shaft 93 to reciprocate that shaft and-an arm 96 thereon engages with lost motion a parallel shaft 95 on which a contact bar 84, Fig. 21, of the reversing switch 81 is mounted, the bar, at the ends of the traverse movement being knocked across to bridge either the " forward " contacts 83, or, the " retracting " ones 82. The traverse mechanism carries an indicator needle 103. Normally, the contact bar 84 is pressed to the " retracting " position by a spring 153, Fig. 10, on a shaft 154 parallel to the shaft 95, the spring engaging an arm 156 on that shaft, but when cleaning fluid is introduced to the blower, a portion is led along a pipe 163, Fig. 2, to a piston 160, Fig. 10, the rod 162 of which then engages an extension 154C of the shaft 154 to displace the shaft and move the spring 153 away from the arm 156. Reduction or failure of the cleaning fluid pressure allows the spring to return the contact bar 84 to the "retracting" position. The shaft 93 of the traverse mechanism also controls the feed of the cleaning fluid to the blower. The fluid passes to the header 44 through a stop cock 126, Fig. 2, and control valve 131, the latter comprising a valve member 133, Fig. 12, urged towards a seat 132 by a spring 138 in opposition to the pressure of the fluid, this pressure, however, normally being multiplied by fluid leaking through a bye-pass 139 to a space behind a piston 136 on the valve member 133. When the blower is retracted, the end of the shaft 93 engages the stem 151 of a slide valve 144 and holds the valve closed against the action of a spring 148 but as the blower is projected inwards, the shaft 93 moves away from the stem 151 and the spring opens the valve 144 establishing communication between the space behind the piston 136 and a drain pipe 142 through a pipe 141 ; this relieves the pressure behind the piston 136 and permits the main fluid flow to lift the valve member 133. In a modification the threaded tubes 56, 62 are rotated and the telescopic tubes 47, 50 have only linear movement.