Backwash apparatus for multi element filter unit

A multielement filter unit including a backwash apparatus, comprising:

• a filter casing;
• process liquid inlet and backwash liquid outlet means at one end of said casing;
• process liquid outlet and backwash liquid inlet means at the other end of said casing;
• a plurality of filter tubes spaced within said filter casing and having one end adjacent said one end of said filter casing and the other end thereof adjacent said other end of said filter casing;
• flange means engaging said filter tubes adjacent said other ends thereof and dividing said filter casing into first and second chambers respectively communicating with said first and other ends of said filter tubes, said other ends of said filter tubes opening through said flange means into said second chamber, said filter tubes being closely spaced from each other, the distance between adjacent filter tubes being not more than about the filter tube radius, said filter tubes lying parallel to each other, three adjacent filter tubes being grouped in mutually close spaced relation to form a compact cluster closely surrounding a narrow open zone therebetween;
• means designed for minimizing installation and operating expense factors in a compact liquid filter in a compact liquid filter unit having plural filter tubes closely spaced within a single compact casing, for providing improved backwash cleaning and for substantially reducing the tendency toward solids buildup over multiple filtration-backwash cycles, including:
• means for removing collected solids from said open zone by flow of backwash liquid from one said filter tube outward through said open zone around the exterior of the adjacent filter tubes, said removing means including stopper units coaxially aligned with the open ends of the filter tubes, said stopper units being normally spaced from said filter tubes in the filtration mode of the filter unit and in parts of the backwash mode thereof, said stopper units including three selectively actuable to close the opposed ends of first and second ones of said three adjacent filter tubes against flow therethrough leaving the third filter tube open to backwash flow thereinto, wherein successive pairs of said poppet units close the opposed ends of their respective filter tubes, such that each of said three adjacent filter tubes is backwashed in sequence while the other two of said adjacent three are closed against liquid flow therethrough.

A multielement filter unit including a backwash apparatus, comprising:

• a filter casing;
• means for flowing process liquid in one direction through the casing and alternately flowing backwash liquid in the opposite direction through said casing;
• a cluster of filter tubes close spaced from each other and located within said filter casing and closely surrounding a narrow open space therebetween, said filer tubes each having one end open to expel filtered process liquid and alternately receive backwash liquid;
• flange means engaging said filter tubes adjacent their open ends and dividing said filter casing into first and second chambers with said open ends of said filter tubes opening through said flange means into said second chamber;
• means designed for minimizing installation and operating expense factors in a compact liquid filter in a compact liquid filter unit having plural filter tubes closely spaced within a single compact casing, for providing improved backwash cleaning and for substantially reducing the tendency toward solids buildup over multiple filtration-backwash cycles, including:
• (a) a cluster of closure means having first positions opposed to and spaced during filtration from said open end of said filter tube for allowing unimpeded filtration flow through said filter tubes and each having a second position closing the opposed filter tube to block all flow therethrough;
• (b) means actuable in the backwash mode of the apparatus for causing said closure means to close the opposed open ends of all but one of said filter tubes of said cluster while leaving the end of said one filter tube open by leaving the corresponding closure means spaced therefrom, said filter tubes of said cluster being sequentially backwashed one at a time, wherein each filter tube has its one end open for at least a part of the backwashing time while the one ends of other filter tubes are closed;
• (c) backwashing means for flowing backwash liquid through the open end of one filter tube and out from said tube through said space along the outside of the other filter tubes of said cluster to dislodge caked solids on said others, while preventing filtration flow of liquid through said other filter tubes to reduce sticking of solids to said other filter tubes due to suction.