Patent Publication Number: US-6210123-B1

Title: Jet pumping device

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a jet pumping device whose efficiency is improved in relation to known jet pumps. 
     The continuous jet pump works according to the principle of injection of a working fluid through a calibrated restriction (nozzle) leading to a high-velocity jet along the axis of a mixing neck. The jet carries along and mixes with the fluid to be pumped according to the momentum exchange principle. The velocity at the mixer outlet is converted to pressure in a divergent channel that follows the mixing neck. 
     The present invention improves pumping efficiencies by acting on the circulation of the pumped fluid and/or of the working fluid. 
     This type of pump can be used notably in petroleum effluent production, whether in surface installations or in bottomhole installations. 
     The advantages afforded by improved-efficiency jet pumps can be: 
     no or very few parts in motion, 
     all fluid types can be pumped (liquids, gases, viscous liquids or liquids containing solids) from a liquid working fluid (water, oil, . . . ), 
     their size is relatively compact and compatible with the dimensions of an oil well or of a delivery pipe. 
     SUMMARY OF THE INVENTION 
     The present invention thus relates to a fluid jet pumping device comprising an injection nozzle intended for injection of a working fluid, placed in a line comprising, from upstream to downstream, a substantially cylindrical barrel, a convergent neck, a mixing channel and a diffuser, said nozzle is placed at the end of a nozzle holder on the longitudinal axis of said line, the pumped fluid circulates in the annular space contained between the barrel and the outside of the nozzle and of the nozzle holder, the orifice of the nozzle has the longitudinal axis as the axis of symmetry. According to the invention, the device consists of one of the following combinations: 
     a) the nozzle holder comprises, in its inner channel, means for rotating the working fluid stream in the nozzle and means for rotating the nozzle around the longitudinal axis, said rotation means being independent of the energy of the working fluid or of the pumped fluid, the nozzle rotating in the opposite direction to the direction of rotation of the working fluid stream; 
     b) the nozzle holder comprises, on the outside, means for rotating the pumped fluid stream, such as blades inclined in relation to the longitudinal axis; 
     c) the nozzle holder comprises, on the outside, means for rotating the pumped fluid stream, such as blades inclined in relation to the longitudinal axis and, in its inner channel, means for rotating the working fluid stream in the nozzle. 
     In a first variant concerning combinations b) and c), the nozzle of the device can be static. 
     In a second variant concerning combinations b) and c), the nozzle can comprise external rotation means independent of the energy of the working fluid or of the pumped fluid. 
     In the previous variant, the nozzle can rotate in the opposite direction to the direction of rotation of the working fluid stream. 
     In the device according to the invention, the means for rotating the pumped fluid stream can consist of a series of blades evenly distributed on the outside of the nozzle holder and inclined in relation to the longitudinal axis at an angle ranging between 10 and 50 degrees. 
     The direction of rotation of the pumped fluid stream can be identical to the direction of rotation of the assembly consisting of the nozzle and of the nozzle holder. 
     The means for rotating the working fluid stream can consist of a flat strip whose width is substantially equal to the inside diameter of the nozzle holder channel, said strip being helical in said channel so as to form two helical channels. The helix pitch is possibly variable, in particular decreasing in the vicinity of the nozzle. 
     The means for rotating the working fluid stream can consist of a stationary turbine in the nozzle channel. 
     The invention relates to an application of the device for pumping an effluent from the bottom of a well to the ground surface. The invention can also be used for surface pumping of a petroleum effluent. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of the invention will be clear from reading the description hereafter of non limitative examples, with reference to the accompanying drawings wherein: 
     FIG. 1 shows a cross-section of a conventional jet pump, 
     FIG. 2 diagrammatically shows the pumping device comprising means for rotating the working fluid injection nozzle, 
     FIGS. 3 a  and  3   b  show a cross-section of a nozzle equipped with means for rotating the working fluid stream, 
     FIG. 4 shows a cross-section of a nozzle equipped, on its outer surface, with means for rotating the pumped fluid, 
     FIGS. 5 show a nozzle including the previous two variants. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 is a cross-sectional view of a jet pumping device according to the prior art. Such a device comprises a nozzle for injecting a working fluid such as water or oil. The inner shape of nozzle  1  is such that working fluid delivery channel  2  has a decreasing section, so that the fluid has a high velocity at the nozzle outlet. The direction of the working fluid jet thus created is substantially parallel to the axis of the nozzle. The fluid to be displaced by the pump circulates in annular space  3  between the outside of the nozzle and walls  4  of the pump barrel. Walls  4  converge at  5 , substantially in the vicinity of the nozzle outlet, and form a neck. From the neck, a line  6 , substantially cylindrical or very slightly conical, constitutes the working fluid and pumped fluid mixing zone. A divergent line  7  that follows the mixing line creates the pressure energy allowing displacement of the two mixed fluids. 
     The energy efficiency of a jet pump can be evaluated by calculating: 
     the dimensionless compression ratio N: 
     
       
           N= (Pref-Pasp)/(Pmot-Pref) 
       
     
     the dimensionless flow rate M: 
     
       
         M=Qasp/Qmot 
       
     
     with: 
     Pref=mixture delivery pressure at the pump outlet 
     Pasp=pumped fluid pressure at the pump inlet 
     Pmot=working fluid injection pressure in the vicinity of the nozzle 
     Qasp=flow rate of the pumped fluid 
     Qmot=flow rate of the working fluid. 
     The energy efficiency η, below 1, is equal to MN for single-phase flows or flows very close to single-phase flows. 
     In order to compare the performances of the different realisation variants of the invention, calculation of η will be used as a basis. 
     FIG. 2 describes the testing means and the realisation principle of a pump according to the invention in the case of the different variants where nozzle  1  and its nozzle holder are driven in rotation by external means. 
     Reference numbers  1 ,  4 ,  6  and  7  respectively refer, as in FIG. 1, to a nozzle, a neck, a mixer and a diffuser. Line  8  supplies the nozzle with working fluid. This delivery line is stationary in relation to the pumping device. The nozzle is fastened to a nozzle holder  9  that rotates freely in relation to barrel  10  of the pump. An assembly  11  consisting of roller bearings and of rotating seals allows the assembly consisting of nozzle  1  and nozzle holder  9  to be driven in rotation by means of a pulley  12 , a belt  13  and motive means  14 , an electric motor for example. A rotating seal  15  connects rotating nozzle holder  9  to stationary delivery line  8 . All these mechanical constituents are well-known to the man skilled in the art and are therefore not described in detail here. 
     Line  16  is connected to the source of fluid to be pumped, line  17  is the line delivering the mixture of pumped fluid and working fluid. 
     Such a device allows to rotate the nozzle around the longitudinal axis of the jet pump system, in either direction. 
     FIGS. 3 a  and  3   b  show the variant wherein the nozzle comprises internally, i.e. in working fluid channel  2 , close to the end of nozzle  1 , means for rotating the working fluid stream so that the jet at the nozzle outlet is always moving mainly with an axial displacement, but combined with a rotating component around the longitudinal axis. The jet thus has the same form as in the prior art, but it rotates around axis  20 . These rotation means can be achieved in multiple ways. For example, a flat strip  21  splitting channel  2  in two can be placed over a length of some centimeters (about 10 cm), said strip being helically deformed so as to form two helical channels opening into the nozzle outlet upstream. The helix possibly has a variable pitch, in particular decreasing on the side close to the nozzle orifice. It is also possible to helically deform a cross-shaped section whose width corresponds to the inside diameter of the nozzle so as to create four helical channels. Other solutions can be used, for example, according to FIG. 3 b , blades  22  inclined in relation to longitudinal axis  20  and fastened to a central core  23  so as to form a stationary turbine that will force the working fluid to rotate around the longitudinal axis. 
     This variant is of interest for improving the energy efficiency only if the nozzle is rotated by an external motive means independent of the working fluid energy, i.e. included in a system according to FIG.  2 . The direction of rotation of the nozzle or of the nozzle holder depends on the direction of rotation of the working fluid jet. Therefore, if the helix of the inner channels of the nozzle or the blades of the turbine are substantially left-hand helices, right-hand rotation is required, or if the helices are right-hand helices, left-hand rotation of the nozzle is required. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Prior art: Conventional jet pump: stationary nozzle and axial jet 
               
            
           
           
               
               
               
            
               
                   
                 M 
                 Efficiency η 
               
               
                   
                   
               
               
                   
                 0.903 
                 0.173 
               
               
                   
                 0.804 
                 0.227 
               
               
                   
                 0.705 
                 0.235 
               
               
                   
                 0.603 
                 0.234 
               
               
                   
                 0.501 
                 0.241 
               
               
                   
                 0.400 
                 0.234 
               
               
                   
                 0.299 
                 0.216 
               
               
                   
                 0.200 
                 0.180 
               
               
                   
                   
               
            
           
         
       
     
     These values are used as reference values for comparison of the variants according to the invention. 
     The dimensions of the reference jet pump are: 
     nozzle and nozzle holder inside diameter=30 mm 
     nozzle and nozzle holder outside diameter=45 mm 
     nozzle orifice diameter=between 6 and 8 mm (6.7 mm for example) 
     pump barrel inside diameter=66 mm 
     mixer neck diameter=about 12 mm 
     mixer length=about 35 mm 
     diffuser angle=about 3° 
     distance between the nozzle orifice and the neck inlet=about 10 mm. 
     Table 2 hereafter shows the results obtained for the device according to FIG. 3 (left-hand helical channels), the nozzle being driven at the rotating speed V (rpm) (right-hand rotation). 
     
       
         
           
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 M 
                 Efficiency η 
                 V (rpm) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 0.6030 
                 0.2731 
                 0 
               
               
                 0.6263 
                 0.2810 
                 94 
               
               
                 0.6453 
                 0.2904 
                 188 
               
               
                 0.6346 
                 0.3142 
                 282 
               
               
                 0.6540 
                 0.3116 
                 376 
               
               
                 0.6638 
                 0.3160 
                 470 
               
               
                 0.6618 
                 0.3012 
                 564 
               
               
                   
               
            
           
         
       
     
     In relation to the configuration of the prior art, it can be noted that the efficiency increases from 0.273 (zero rotation) to 0.316 (500 rpm rotation) for values of M ranging between 0.60 and 0.66. A 0.082 gain is obtained in relation to the reference values. The efficiency gain reaches a maximum value for a rotation ranging between 280 and 500 rpm. 
     FIG. 4 is a perspective sectional view of another variant of the invention that consists in arranging blades  24  on the outer surface of nozzle  1  or of nozzle holder  9  so as to rotate the pumped fluid stream. FIG. 4 shows a series of blades  24  evenly arranged on the outer surface of the nozzle or of the nozzle holder, near to the neck, but before the convergent part of the nozzle. The blades can be inclined in relation to the longitudinal axis at an angle ranging between 10 and 50 degrees. The blades can consist of right-hand or left-hand helical strips. If the nozzle is stationary in relation to the pump barrel. the blades can be fastened to either barrel  4  or nozzle holder  9 , or to both. 
     In a variant, the nozzle is rotated. The nozzle thus equipped with outer blades must rotate in the same direction as the blades helix, i.e. right-hand blades for right-hand rotation. 
     The test results given in Tables 3 and 4 were obtained respectively with a stationary nozzle and a nozzle rotating at a speed of 500 rpm. 
     The blades consist of helical vanes of length L and of a height corresponding to annular space  3  between nozzle holder  9  and barrel  4 . 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Outer blades, without nozzle rotation 
               
            
           
           
               
               
               
            
               
                   
                 M 
                 Efficiency η 
               
               
                   
                   
               
               
                   
                 0.9470 
                 0.1816 
               
               
                   
                 0.8112 
                 0.2802 
               
               
                   
                 0.7047 
                 0.2881 
               
               
                   
                 0.6071 
                 0.2833 
               
               
                   
                 0.5052 
                 0.2675 
               
               
                   
                 0.4012 
                 0.2475 
               
               
                   
                 0.2998 
                 0.2134 
               
               
                   
                   
               
            
           
         
       
     
     The efficiency is of the order of 0.265 for M ranging between 0.5 and 0.8. The gain is 0.047 when M is 0.6 in relation to the reference values. 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Outer blades, with nozzle rotation (500 rpm) 
               
            
           
           
               
               
               
            
               
                   
                 M 
                 Efficiency η 
               
               
                   
                   
               
               
                   
                 0.8460 
                 0.1535 
               
               
                   
                 0.7996 
                 0.3105 
               
               
                   
                 0.7035 
                 0.3107 
               
               
                   
                 0.6071 
                 0.2900 
               
               
                   
                 0.6016 
                 0.2920 
               
               
                   
                 0.4000 
                 0.2521 
               
               
                   
                 0.3036 
                 0.2181 
               
               
                   
                   
               
            
           
         
       
     
     The maximum efficiency is 0.31 when M is 0.8, and 0.29 when M ranges between 0.5 and 0.8. The maximum gain is 0.09 in relation to the reference values when M is 0.8. 
     FIGS. 5 a  and  5   b  show the variant according to the invention wherein the nozzle is internally equipped with helical channels (FIG. 5 a ) or with a stationary turbine  22 , and with outer blades  24 . Nozzle holder  9  can be equipped with the external rotation means according to FIG.  2 . Rotation is a right-hand rotation the inner channels or turbine  22  form a left-hand helix, and outer blades  24  a right-hand helix. 
     The results are given in Tables 5 and 6 for an assembly according to FIG. 5, with a stationary nozzle and a nozzle rotating at 500 rpm respectively. 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 M 
                 Efficiency η 
               
               
                   
                   
               
             
            
               
                   
                 0.8460 
                 0.1535 
               
               
                   
                 0.7996 
                 0.3105 
               
               
                   
                 0.7035 
                 0.3107 
               
               
                   
                 0.6071 
                 0.2900 
               
               
                   
                 0.6016 
                 0.2920 
               
               
                   
                 0.4000 
                 0.2521 
               
               
                   
                 0.3036 
                 0.2181 
               
               
                   
                 0.8479 
                 0.1472 
               
               
                   
                 0.7837 
                 0.3251 
               
               
                   
                 0.7084 
                 0.3169 
               
               
                   
                 0.6035 
                 0.3085 
               
               
                   
                 0.5047 
                 0.2933 
               
               
                   
                 0.3866 
                 0.2497 
               
               
                   
                   
               
            
           
         
       
     
     The maximum efficiency is 0.325 when M is 0.78 and 0.30 when M ranges between 0.4 and 0.78. The maximum gain is 0.098 in relation to the reference values when M is 0.8. 
     It can therefore be observed that rotation of the nozzle through external driving means independent of the working fluid or pumped fluid energy improves the efficiency of jet pumps. Surprisingly, rotation of the pumped fluid and/or of the working fluid also noticeably improves the efficiency of this type of pump.