System having foam busting nozzle and sub-surface mixing nozzle

Abstract

A surface foam diffuser and digester tank system prevents and/or suppresses the formation of foam during digestion. The system includes a first nozzle disposed above a top surface of the at least partially liquid contents, a splash plate positioned adjacent to the first nozzle outlet, and a second nozzle disposed below the top surface of the at least partially liquid contents for suppressing foaming in the large processing tanks. The system nozzles each have an inlet for receiving pressurized liquid and an outlet for ejecting a liquid stream into the tank, the depth of the second nozzle and the direction of the liquid stream there from being such that rotation of the top surface is facilitated. The spray of the first nozzle, as dispersed by the splash plate, reduces foam on at least a portion of the top surface, with the rotation of the top surface bringing each portion of the top surface to eventually fall within the reducing spray.

What is claimed is: 
     
         1 . A tiered nozzle system for suppressing foam on a top surface of fluid material substantially filling a large digester tank, the system comprising:
 a first nozzle positioned to remain above the top surface of the fluid material when the digester tank is substantially filled, the nozzle having an inlet for receiving pressurized liquid and an outlet for discharging a liquid stream into the digester tank;   a splash plate positioned below the outlet of the first nozzle such that the splash plate contacts a discharging liquid stream at an angle of inclination relative to the stream direction to thereby deflect at least a portion of the stream upward and disperse the liquid stream over a greater portion of the top surface than the liquid stream would otherwise cover without a splash plate; and   a second nozzle disposed below the top surface of the at least partially liquid contents, the second nozzle having an inlet for receiving pressurized liquid and an outlet for discharging a liquid stream directly into the fluid material, the position of the second nozzle and the direction of the discharged liquid stream being such that rotation of the top surface is facilitated.   
     
     
         2 . The system of  claim 1 , wherein the first and second nozzle are connected at their respective inlets. 
     
     
         3 . The system of  claim 1 , wherein the first nozzle and the second nozzle are secured to and positioned proximate an inner periphery of the digester tank. 
     
     
         4 . The system of  claim 3 , wherein the outlet of the first nozzle is directed toward the center of the digester tank. 
     
     
         5 . The system of  claim 1 , wherein the splash plate disperses the liquid stream over at least 20% of the top surface. 
     
     
         6 . The system of  claim 1 , wherein the second nozzle is disposed at a depth of no more than 30% of the digester tank contents below the top surface. 
     
     
         7 . The system of  claim 6 , wherein the second nozzle is disposed at a depth of no more than 20% of the digester tank contents below the top surface. 
     
     
         8 . The system of  claim 6 , wherein the second nozzle is disposed at a depth of no more than 10% of the digester tank contents below the top surface. 
     
     
         9 . The system of  claim 2 , wherein the first and second nozzles are positioned such that the direction of the liquid stream from the first nozzle is offset from the direction of the liquid stream from the second nozzle. 
     
     
         10 . A digester tank system comprising:
 a digester tank containing material having at least a partially liquid composition prone to foaming as a result of gas byproducts from biological digestion;   a discharge line connected to the bottom of the digester tank;   a pump having an inlet connected to the discharge line;   a feed line connected to a outlet of the pump;   a first nozzle disposed above a top surface of the at least partially liquid material, the nozzle having an inlet for receiving pressurized liquid from the feed line and an outlet for ejecting a liquid stream in a direction toward one of either a center or a side of the digester tank;   a splash plate positioned adjacent to the first nozzle outlet contacting the liquid stream at an angle of inclination relative to the stream direction to thereby disperse the liquid stream over a greater portion of the top surface; and   a second nozzle disposed below the top surface of the at least partially liquid contents, the nozzle having an inlet for receiving pressurized liquid from the feed line and an outlet for ejecting a liquid stream into the digester tank, the depth of the nozzle and the direction of the liquid stream being such that rotation of the top surface is facilitated.   
     
     
         11 . The system of  claim 10 , wherein the digester tank is a waste-water treatment tank comprising one of either an aerobic digester or an anaerobic digester. 
     
     
         12 . The system of  claim 10 , wherein the inlet of the first nozzle and inlet of the second nozzle are aligned and connected. 
     
     
         13 . The system of  claim 10 , wherein the first nozzle and the second nozzle are positioned proximate an inner periphery of the digester tank. 
     
     
         14 . The system of  claim 10 , wherein the outlet of the first nozzle is directed toward the center of the digester tank. 
     
     
         15 . The system of  claim 10 , wherein the second nozzle is disposed no more than one foot below the top surface. 
     
     
         16 . The system of  claim 10 , further comprising a plurality of mixing nozzles positioned proximate a bottom surface of the tank. 
     
     
         17 . The system of  claim 16 , wherein outlets of the mixing nozzles are aimed such that a discharging stream creates a liquid flow pattern in the digester tank contents. 
     
     
         18 . The system of  claim 10 , wherein the first and second nozzles are positioned such that the direction of the liquid stream from the outlet of the first nozzle is offset from the direction of the liquid stream from the outlet of the second nozzle. 
     
     
         19 . The system of  claim 10 , wherein the second nozzle is disposed at a depth of no more than 30% of the tank contents below the top surface. 
     
     
         20 . The system of  claim 19 , wherein the second nozzle is disposed at a depth of no more than 20% of the tank contents below the top surface. 
     
     
         21 . The system of  claim 19 , wherein the second nozzle is disposed at a depth of no more than 10% of the tank contents below the top surface.