Continuously and automatically functioning device for the drainage of sludge, especially of sewage sludge

A continuously and automatically operating arrangement for draining sewage sludge treated with a flocculent, comprising:

• a screw conveyor having a driven screw with a shaft and a helix;
• a screen wall surrounding said driven screw;
• said screw conveyor having a first cylindrical wall enclosing a substantially large cross-sectional area and a first part of said screen, said first part of said screen having substantially large screen openings;
• a conical wall connected to said first cylindrical wall and having a cross-sectional area that decreases in direction of flow through said screw conveyor;
• a pressure section connected to said conical wall, the helix in said pressure section having a decreasing lead and the shaft having a constant diameter at an entrance side of said pressure section;
• a conically-shaped member on said shaft in an end zone of said pressure section;
• said screen forming a screened enclosure surrounding said driven screw within said screw conveyor;
• said conically-shaped member being mounted on a portion of said shaft that is free of helical surfaces for producing compacting of sludge free of thrust thereon in a final region of said pressure section;
• said conical wall being a closed wall;
• said screw conveyor having an inclined position;
• additional pressure sections arranged in consecutive sequence in the direction of flow, said shaft having increased diameters in sequence in said pressure sections;
• additional conically-shaped members on said shaft in said additional sections and having increased outside diameters in sequence which a helix free;
• said screen having openings of reduced width in said pressure sections in the direction of flow, screen openings adjacent said cylindrical wall having a width of substantially 1-0.5 mm, screen openings adjacent said conical wall having a width of substantially 0.25 mm, screen openings in said additional pressure sections having further decreased widths between 0.25 and 0.1 mm;
• means for rinsing and cleaning said screen with filtration water;
• an outside wall enclosing said screen;
• means for heating sludge to be drained;
• a first flocculation reactor connected to said screw conveyor for carrying out a pre-thickening operation and having a substantially fine screen for pre-drainage of sludge;
• a second flocculation reactor located between said first flocculation reactor and said screw conveyor and having a screen with substantially large openings for carrying out a post-thickening operation.

A continuously and automatically operating arrangement for draining sewage sludge treated with a flocculent, comprising:

• a screw conveyor having a driven screw with a shaft and a helix;
• a screen wall surrounding said driven screw;
• said screw conveyor having a first cylindrical wall enclosing a substantially large cross-sectional area and a first part of said screen, said first part of said screen having substantially large screen openings;
• a conical wall connected to said first cylindrical wall and having a cross-sectional area that decreases in direction of flow through said screw conveyor;
• a pressure section connected to said conical wall, the helix in said pressure section having a decreasing lead and the shaft having a constant diameter at an entrance side of said pressure section;
• a conically-shaped member on said shaft in an end zone of said pressure section;
• said screen forming a screened enclosure surrounding said driven screw within said screw conveyor;
• said conically-shape member being mounted on a portion of said shaft that is free of helical surfaces for producing compacting of sludge free of thrust thereon in a final region of said pressure section, said sludge being rearranged and mixed by said portion of said shaft that is free of a helical surface so that different areas of sludge come into contact with said screen;
• said screw conveyor has additional pressure sections arranged consecutively in sequence in the flow direction, said shaft having increased diameters in said additional pressure sections;
• said additional pressure sections having additional conically-shaped members on said shaft with correspondingly increased outside diameters that are helix-free.