Pumping unit for delivery of liquid medium from a vessel

Abstract

A pumping unit for delivering a liquid medium from a low pressure vessel such that the delivered medium has sufficiently high pressure, by providing the liquid medium in the form of separated pulses.

1 . A pumping unit for delivering a liquid medium from a vessel in the form of separated pulses; said pumping unit comprising:
 a conduit, which is at least partially contained within said vessel, wherein a proximal end of said conduit is situated in a vicinity of a bottom of said vessel;   a first check valve installed on a lower section of said conduit;   an electrical heating element for heating a lower portion of said conduit; and   a second check valve installed on an upper section of said conduit;   wherein heating of said heating element causes said liquid medium to form vapors in said conduit, said vapors causing said first check valve to close and causing said second check valve to open; and upon condensation of said vapors, said second check valve closes.   
   
   
       2 . The pumping unit of  claim 1 , wherein said liquid medium comprises a cryogen. 
   
   
       3 . The pumping unit of  claim 2 , wherein said electrical heating element has low thermal inertia. 
   
   
       4 . The pumping unit of  claim 3 , wherein said conduit comprises a layer of an outer thermal insulation for reducing heating of the surrounding liquid medium by said electrical heating element. 
   
   
       5 . The pumping unit of  claim 1 , wherein the condensation occurs in a section of the central feeding conduit situated in immediate vicinity of the bottom of the vessel. 
   
   
       6 . The pumping unit of  claim 1 , wherein electrical heating pulses are applied to the heating element, and duration of the electrical heating pulses is significantly less than a time required for floatation of vapor bubbles generated by said electrical heating pulses to the upper section of the central feeding conduit. 
   
   
       7 . The pumping unit of  claim 1 , wherein said second check valve is of a normally open type and wherein said first check valve is of a normally open type. 
   
   
       8 . The pumping unit of  claim 1 , wherein said second check valve is of the normally closed type and wherein said first check valve is of a normally open type. 
   
   
       9 . The pumping unit of  claim 1 , wherein the electrical heating element is of a resistive type. 
   
   
       10 . The pumping unit of  claim 1 , wherein the electrical heating element is of an inductive type. 
   
   
       11 . The pumping unit of  claim 1 , wherein said separate pulses are under high pressure of at least about 1.5 atmospheres. 
   
   
       12 . A pumping unit for feeding liquid cryogen from a Dewar flask, comprising:
 a central feeding conduit;   seal means for sealing said central feeding conduit to the Dewar flask;   two check valves installed on an upper section and a lower section respectively of said central feeding conduit;   an electrical heating element, situated in immediate contact with or adjacent a section of said central feeding conduit, said section being above and adjacent to said lower check valve;   a power-control unit supplying pulses of electrical current to said electrical heating element; and wherein the liquid cryogen is fed through said central feeding conduit from the Dewar flask.   
   
   
       13 . The pumping unit of  claim 12 , wherein the upper check valve is of a normally closed type. 
   
   
       14 . The pumping unit of  claim 12 , wherein the lower check valve is of a normally open type. 
   
   
       15 . The pumping unit of  claim 12 , wherein the electrical heating element functions as a resistor. 
   
   
       16 . The pumping unit of  claim 12 , wherein the electrical heating element comprises a combination of an inductor and an adjacent section of the central feeding conduit, the adjacent section comprising a ferromagnetic material. 
   
   
       17 . The pumping unit of  claim 12 , further comprising a condensation section of the central feeding conduit, the condensation section including a plurality of outer fins. 
   
   
       18 . The pumping unit of  claim 12 , further comprising a condensation section of the central feeding conduit, the condensation section including a plurality of internal fins. 
   
   
       19 . The pumping unit of  claim 12 , wherein said central feeding conduit further comprises a section constructed as a bellows. 
   
   
       20 . The pumping unit of  claim 12 , further comprising a buffering vessel in fluid communication with an outer section of the central feeding conduit, said buffering vessel comprising a safety valve and a pressure gauge. 
   
   
       21 . The pumping unit of  claim 20 , wherein said buffering vessel further comprises a heater for evaporating the cryogen provided from said Dewar flask. 
   
   
       22 . The pumping unit of  claim 21 , wherein said buffering vessel further comprises an outlet connection and a shut-off valve. 
   
   
       23 . The pumping unit of  claim 21 , wherein the buffering vessel is equipped with a safety valve and a pressure gauge. 
   
   
       24 . The pumping unit of  claim 12 , wherein the lower section of the central feeding conduit comprises a plurality of branches, each branch being provided with an independent check valve, and an electrical heating unit, the pumping unit further comprising a sensing unit and a power control unit, wherein said sensing unit detects an angle and direction of inclination of said Dewar flask and wherein said power-control unit energizes a selected electrical heating unit according to data communication from said sensing unit, to heat a branch that is immersed with its proximal end into the liquid cryogen in said Dewar flask. 
   
   
       25 . The pumping unit of  claim 23 , further comprising a bellows section incorporated into each branch of the central feeding conduit. 
   
   
       26 . The pumping unit of  claim 12 , wherein the central feeding conduit includes an external vacuum insulation in the form of a vacuum insulated jacket; a proximal edge of said vacuum insulated jacket is sealed with the central feeding conduit above the lower check valve and a distal edge of the jacket is sealed with said central feeding conduit distally to the upper check valve and externally to the Dewar flask. 
   
   
       27 . The pumping unit of  claim 25 , wherein said jacket further comprises an internal threading, such that an internal diameter of said jacket is fitted to an outer diameter of the central feeding conduit. 
   
   
       28 . The pumping unit of  claim 27 , wherein outer sections of said vacuum insulated jacket and said central feeding conduit comprise a flexible bellows.