GB457891A - Improvements in and relating to digesters and valves therefor - Google Patents

Abstract

457,891. Digesters. SPENCER, E., 8, Clive Street, and MITCHELL, F. S., Chartered Bank Buildings, both in Calcutta, India. July 15, 1935, No. 20171. [Class 64 (i)] [See also Group XXIX] In a digester of the Sinclair type having a perforated inner bottom 4, an upper valve casing 7 in the form of a dome or a cone or with conical projections above this bottom has discharge openings 8 for digested pulp, and a lower cylindrical valve casing 9 between the inner bottom and a discharge opening 16 for pulp in the bottom of the digester has openings 10 for liquor circulation ; a rotatable valve 12 with a cylindrical extension 14 apertured at 13, 15 in the valve casings opens one set of openings and closes the other. The conical parts of the upper casing and valve have small holes 43 allowing circulation of water when the lower valve is open and the upper valve is closed for pulp. The inner parts 12, 14 of the valves are first lowered and then rotated by a central shaft 24, a stop 40 limiting the motion. The shaft 24 has a collar 31, is threaded at 29 and has a lower washer 35 limiting the distance of lowering of the valve before rotation, which is prevented during lowering by a stop 40 engaging a vertical groove 41 in the valve. The liquid is circulated through external tubes by a force pump or through internal vomit pipes 18 under which air steam or water is injected. Valves 19 may close the tops of vomit pipes so that pulp to be discharged may be stirred by the jets or floated off the inner bottom 4 when the lower openings 10 are closed. The inner bottom 4 may be constructed with ridges according to Specification 458,863.