Ejector Device for Forming a Pressurized Mixture of Liquid and Gas, and Use Therefore

Abstract

Ejector device for forming a pressurized mixture of liquid and gas, comprising a suction chamber and a diffuser. The suction chamber comprises an injection nozzle for producing a jet of liquid flowing in a longitudinal direction, a gas inlet for admitting into the suction chamber a gas to be driven by the liquid jet, and an outlet opening for discharging the liquid jet and the driven gas from the suction chamber. The diffuser is connected to the outlet opening of the suction chamber and has, in the longitudinal direction, a transversal section that increases from the outlet opening, the diffuser being situated immediately after the outlet opening of the suction chamber.

1 . An ejector device for forming a pressurized mixture of liquid and gas, comprising a suction chamber and a diffuser, wherein the suction chamber comprises:
 an injection nozzle for producing a jet of liquid flowing in a longitudinal direction (X);   a gas inlet for admitting into the suction chamber a gas to be driven by the liquid jet; and   an outlet opening for discharging the liquid jet and the driven gas from the suction chamber;   
       wherein the diffuser is connected to the outlet opening of the suction chamber and has, in the longitudinal direction, a transversal section that increases from said outlet opening, the diffuser with increasing section being situated immediately after the outlet opening of the suction chamber, and wherein the diffuser comprises at least one first conical portion that has a first angle of between 0.1 and 7 degrees. 
     
     
         2 . An ejector device according to  claim 1 , wherein the first angle is between 1.5 and 4 degrees. 
     
     
         3 . An ejector device according to  claim 1 , wherein the diffuser also comprises a second conical portion continually in the extension of the first portion in the longitudinal direction, said first portion having a second angle greater than the first angle. 
     
     
         4 . An ejector device according to  claim 3 , wherein the second angle is between 5 and 15 degrees, and preferably of the order of 7 degrees. 
     
     
         5 . An ejector device according to  claim 1 , wherein the diffuser also comprises a second portion continually in the extension of the first portion in the longitudinal direction, said second portion having a convex profile shape. 
     
     
         6 . An ejector device according to  claim 5 , wherein the convex second portion has an angle that progressively increases in the longitudinal direction from the first angle to an angle less than 15 degrees, and preferably of the order of 10 degrees. 
     
     
         7 . An ejector device according to  claim 1 , wherein the diffuser is substantially coaxial to the injection nozzle and to the outlet opening of the suction chamber. 
     
     
         8 . An ejector device according to  claim 1 , wherein:
 the outlet opening has a neck surface S c  perpendicular to the longitudinal direction,   the injection nozzle has a nozzle surface S 2  inside the nozzle and perpendicular to the longitudinal direction, and   a geometrical ratio R is the ratio between the nozzle surface S 2  and the neck surface S c , said geometrical ratio R being between 0.5 and 0.9.   
     
     
         9 . An ejector device according to  claim 1 , wherein:
 the injection nozzle has one end in the longitudinal direction,   the outlet opening has a circular section with a neck diameter D c , and   the end is situated a retraction distance x 2  from the outlet opening, said retraction distance x 2  being between one and five times the neck diameter D c .   
     
     
         10 . An ejector device according to  claim 1 , wherein the suction chamber comprises walls in the longitudinal direction extending radially in said suction chamber, so that the gas flows in the suction chamber with a flow with little turbulence, without rotation and with substantially uniform axial speed distribution. 
     
     
         11 . An ejector device according to  claim 1 , wherein the injection nozzle comprises liquid channelling means suitable for obtaining, in the nozzle after such channelling means, a flow of the liquid with little turbulence, without rotation and with substantially uniform axial speed distribution. 
     
     
         12 . An ejector device according to  claim 11 , wherein the liquid channelling means in the nozzle are chosen from:
 a device that has walls extending in the longitudinal direction, and   a device that has walls extending in the longitudinal direction, said walls having a honeycomb shape, and   a device comprising a wall in a direction that is substantially perpendicular to the longitudinal direction and comprising holes for distributing the liquid flow in a substantially uniform manner in the transversal section of the nozzle.   
     
     
         13 . Use of an ejector device according to  claim 1 , wherein:
 the following are measured: a gas suction pressure p 1  at the gas inlet, a liquid feed pressure p 2  feeding the injection nozzle, a discharge pressure p 3  of the gas and liquid mixture downstream of the diffuser, and   at least one of said pressures is set so that a compression parameter defined by the following formula:   
       
         
           
             
               
                 Ψ 
                 = 
                 
                   
                     
                       p 
                       3 
                     
                     - 
                     
                       p 
                       1 
                     
                   
                   
                     
                       p 
                       2 
                     
                     - 
                     
                       p 
                       1 
                     
                   
                 
               
               , 
             
           
         
       
       is between 0.4 and 0.6. 
     
     
         14 . Use of an ejector device according to  claim 1 , wherein:
 the following are measured: a gas suction pressure p 1  at the gas inlet, a liquid feed pressure p 2  feeding the injection nozzle, a discharge pressure p 3  of the gas and liquid mixture downstream of the diffuser, and   said liquid feed pressure p 2  is set to plus or minus twenty percent of an optimal pressure p 2,opt , such that:
     p   2,opt =2 ·p   3   −p   1 .