Method for making a bundle of helical tubes and apparatus for separating impurities from a polluted liquid

A method for making a bundle of helical tubes from flexible tubing, each tube having a common length and cross sectional dimensions, a common helical axis and each tube having an open top end lying on a top plane and a common bottom end lying on a common bottom plane and each helical tube having a common slope, tan B, said method comprising:

• a) cutting said flexible tubing to provide tubes having said commonly length;
• b) attaching said top end of a first one of said tubes to a standpipe at a first location;
• c) wrapping said first tube around said standpipe to form a first helical tube;
• d) attaching said bottom end of said helical tube to said standpipe at a second location;
• e) using a guide means to adjust the shape of said first helical tube to have said slope along its said entire length;
• and
• f) laying additional ones of said tubes around said standpipe and securing said tubes in position to form said bundle of tubes, with said top and bottom ends lying in common top and bottom planes respectively.

A method for making a molding surface wherein a location, P, on said surface, having polar coordinates:

• r, the radial coordinate;
• .phi., the azimuthal coordinate;
• and z, the rectangular coordinate orthogonal to r and .phi.;
• is given by:
• z=.phi.r(tan B)
• and wherein tan B is a parameter defining the slope of said molding surface, said method comprising:
• a) providing a rectangular sheet having a first and second edge wherein the ratio of the length of said first edge of said sheet divided into the length of said second edge of said sheet is tan B;
• b) cutting said sheet along a diagonal to form first and second sheets that are right triangles;
• c) bending each said sheet to form a cylinder about an axis, said cylinder having a base which is a circle with a center and whose perimeter is said first edge and having an edge whose slope with respect to said base is tan B;
• d) cutting a plurality of strings, each having two ends;
• e) attaching one end of each said strings to said center;
• f) attaching the other ends to said sloped edge thereby forming a tent of strings wherein each string is tangent to said surface defined by:
• z=.phi.r tan B;
• g) forming a sculpture bounded by said base, said bent sheet and said tent of strings to provide a negative surface of said molding surface;
• h) placing said second bent sheet onto said first bent sheet with said sloped edges coincident thereby forming a form for casting;
• i) casting a permanent molding material against said negative surface and permitting said casting to harden;
• and
• j) removing said sculpture.

A clarifying apparatus for separating impurities from a polluted liquid comprising in operative combination:

• a) a tank having a generally cylindrical upper section for housing a settling tube bundle, and a lower conical section having a sludge outlet port therein;
• b) a settling tube bundle assembly having a central standpipe forming a reaction zone surrounded by a plurality of settling tubes secured thereto;
• c) each of said settling tubes having a common length, a common cross-sectional dimension, a top and a bottom end, and each formed into a continuous helix having a common slope;
• d) said settling tube bundle supporting said standpipe generally axially centrally of said tank in said upper cylindrical section and providing a quiescent settling zone below the bottom end of said tubes;
• e) means for supporting said tank with said standpipe in a generally vertical orientation;
• f) means for introduction of said polluted liquid into the top end of said standpipe into said reaction zone;
• g) a circumferential weir disposed radially outward of said tube bundle and including an outlet therefrom for removal of clarified liquid.