Multi-stage eductor apparatus

Abstract

A multi-stage eductor apparatus includes a first stage eductor with an inlet, an outlet, and a venturi throat between the inlet and outlet into which a driving fluid is injected to flow from the outlet and create a suction at the inlet for drawing material into the inlet and through the first stage eductor with the driving fluid, and at least a second stage eductor of the same or similar configuration, with the inlet of the second stage eductor connected directly to the outlet from the first stage eductor, thereby increasing the suction at the inlet to the first stage eductor and maintaining the suction at the inlet to the first stage eductor through a wide range of driving fluid flow rates.

1 . A multi-stage eductor apparatus, comprising 
 a first venturi-type eductor stage having a longitudinal axis, a first stage material inlet centered on said longitudinal axis, and a first stage material outlet in coaxial alignment with said first stage material inlet; and    a second venturi-type eductor stage having a longitudinal axis, a second stage material inlet centered on said longitudinal axis, and a second stage material outlet in coaxial alignment with said second stage material inlet, said second stage material inlet connected directly to said first stage material outlet with said longitudinal axes of said first stage eductor and said second stage eductor in coaxial alignment, forming a passageway for the flow of material from said first stage eductor directly into and through said second stage eductor.    
   
   
       2 . The multi-stage eductor apparatus, of  claim 1 , wherein said first stage eductor comprises 
 a hollow first stage body with open first and second ends and a longutidinal axis extending through said first and second open ends, said open first end of said first stage body being a first stage suction inlet for the introduction of flowable material into said first stage body, having an elongate first stage venturi tube with a hollow interior, open first and second ends and a longitudinal axis, connected at said first end to said first stage body in coaxial alignment therewith, said interior of said first stage venturi tube narrowing in cross-sectional dimension from said first end to a venturi throat and increasing in cross-section dimension from said venturi throat toward said second end, having a first stage driving fluid inlet in fluid flow communication with at least one first stage driving fluid nozzle for directing a driving fluid into said interior of said first stage venturi tube adjacent to said first end thereof in the direction of said second end of said first stage venturi tube.    
   
   
       3 . The multi-stage eductor apparatus of  claim 1 , wherein said second stage eductor comprises 
 a hollow second stage body with open first and second ends and a longutidinal axis extending through said first and second open ends, said open first end of said second stage body being a second stage suction inlet for the introduction of flowable material into said second stage body, having an elongate second stage venturi tube with a hollow interior, open first and second ends and a longitudinal axis, connected at said first end to said second stage body in coaxial alignment therewith, said interior of said second stage venturi tube narrowing in cross-sectional dimension from said first end to a venturi throat and increasing in cross-section dimension from said venturi throat toward said second end, having a second stage driving fluid inlet in fluid flow communication with at least one second stage driving fluid nozzle for directing a driving fluid into said interior of said second stage venturi tube adjacent to said first end thereof in the direction of said second end of said second stage venturi tube.    
   
   
       4 . The multi-stage eductor of  claim 1 , further comprising 
 a third venturi-type eductor stage having a longitudinal axis, a third stage material inlet centered on said longitudinal axis, and a third stage material outlet in coaxial alignment with said third stage material inlet, said third stage material inlet connected directly to said second stage material outlet with said longitudinal axes of said first stage eductor, said second stage eductor, and said third stage eductor in coaxial alignment, forming a passageway for the flow of material from said first stage eductor directly into and through said second stage eductor and from said second stage eductor directly into and through said third stage eductor.