| 摘要 |
<PICT:0711034/III/1> <PICT:0711034/III/2> An apparatus for catalysis, absorption, ion-exchange, filtration, drying or other chemical reaction comprises a channel having inlet and outlet connections for fluid flow through the channel and a bed of particulate material in the channel between the inlet and outlet connections retained by the field of an electromagnet. The particles may be disposed in the channel in layers of increasing particle size in the direction of flow through the channel and one or more non-magnetic constituents (e.g. filter aids) may be supported by or included with the mass. A slurry of ferromagnetic particulate material, e.g. ferrosilicon or magnetic stainless steel, in a viscous liquid such as glycerine, is fed through a duct 9, Fig. 1, and down a non-magnetic channel 1 spanned by an electromagnet 4 which is being energized, a splitter box 12 being positioned so that a compartment 14 is opposite an outlet duct 11 to collect any discharge. The ferromagnetic material is held in the magnetic field above a supporting grille 2 to form a filter bed 10. The bed may be constructed in layers by feeding a sequence of slurries containing progressively smaller particles. When formed the bed is washed with water fed in through the duct 9 after which the splitter box 12 is moved across to the position shown. Liquid to be filtered is then forced up a pipe 22 from a tank 17 by passing compressed air through a pipe 21 into the tank 17, which has been filled through a pipe 18. Filtrate passes into the compartment 13. The filtration operation is stopped by closing the compressed air cock 20, and the bed 10 together with any filter cake is discharged by reversing and switching off the electromagnet current, the splitter box 12 being first moved across to the opposite position. Should the current to the electromagnet coils be switched off during filtration a valve 24, normally held closed by the field due to a coil 26 in series with the magnet coils, opens to release the air pressure above the liquid in the tank 17, thus stopping flow of liquid up the pipe 22. The movement of the splitter box 12 may also be controlled automatically by the magnet current so that a bed collapsing on failure of the current will be discharged into the appropriate compartment. The grille 2 may consist of a non-magnetic stainless steel ring 27, Fig. 2 resting on lugs 3, Fig. 1. and combined with cross-members 28 of similar material having soft iron inserted members 29 for controlling the distribution of magnetic field across the channel. The apertures 30 are square in plan, and have sloping side-walls 31 to aid in discharge of the filter bed. The grille may be dispensed with. |
