Tubular filter element to sterilise milk, wine, fruit juice etc. - has reduced flow channel so that increased velocity cleans membrane

摘要

Appts. comprises a tubular filter element made up of a macroporous, cylindrical support sleeve contg. a liner of microporous membrane. The pores of the membrane are 0.1-0.2 microns and those of the support sleeve 1-10 microns. Liq. is pumped through the element passage under controllable back pressure. Filtrate is collected from the exterior of the sleeve while unfiltered liq. is recycled to the pump. A coaxial core is now fitted in the elements passage so that liq. has to pass through a narrow, annular channel between the membrane and the core. The core is pref. ringed with regular corrugations so that the cross-section of the flow channel fluctuates cyclically through the length of the element. Supply of liq. to and discharge from the flow channel is pref. via coaxial pipe stubs which support the core and extend through passage end caps. Filtrate is then drawn from a shell which encases the support sleeve. By reducing the cross-section available for flow through the passage to a narrow annular channel, the velocity of liq. flow across the membrane surface is considerably increased. This reduces the rate of deposition on the membrane and means that filtration periods can be extended before cleaning is necessary. A corrugated core improves the scrubbing action.