| 摘要 |
730,917. Filters. BLACK-CLAWSON CO. March 20, 1953 [March 20, 1952], No. 7750/53. Class 46. A rotary suction drum filter of the type including a cylindrical casing 21, a cylindrical strainer 22 spaced from its outer surface, a circumferential row of longitudinally-extending cells 11, an outlet 11a in the casing leading from each cell 11, and rearwardly-bent discharge ducts 12 connecting the outlets with the interior of the drum has means such as pipe 13, connecting each cell with the rear portion of its discharge duct, for admitting air into the cells during their upward movement so that no "trap" is formed in the discharge ducts 12 before a sufficient quantity of liquid is present in them for maintaining vacuum in the cells until the outlet ends of the ducts 12 have moved below the inner liquid level. A cell 11b is shown near its lowermost position in Fig. 1, in which position, as a result of the dimensions chosen for the cell, it is not completely filled, and the outlet 11a is not covered with liquid. After moving to the position of Fig. 2 (not shown), the outlet 11a is completely closed by liquid, but air entering the cell through the pipe 13b permits more liquid to flow from the cell into the discharge duct 12b, this state of affairs continuing until the pipe 13b has reached the position of Fig. 3 in which the liquid in duct 12b closes the pipe opening. Liquid continues to pass through the strainer 22 into the cell 11b and thence into the duct 12b where it is supported by the continuously-increasing vacuum in the cell due to the expansion of the air trapped within the cell. Instead of a pipe 13 each discharge duct 12 may be provided with a hollow bead 14, Fig. 5, preferably set at such an angle (as shown) as to guide the discharging liquid to the filtrate outlet and thus keep the interior liquid level low. The interior liquid level may be kept substantially constant (so as to control the capacity of the apparatus) by providing for varying the drum speed such as by a variable speed drive 25 governed by the interior liquid level. |
