Cryogenic pump and inlet header

Abstract

A header and a pump end for a cryogenic pump are provided for efficient liquid pumping operation. The header directs supplied liquid into a sump and gas into a freeboard. The liquid in the header can be distributed along the header and decanted over a weir to the sump, the liquid being drawn from the sump and up through the vessel to the pump end. Gas in the freeboard is collected for venting or return to the liquid source. Pump head plunger stroke can be lengthened and operated at slower stroke rates using a large cross-sectional area intake and discharge valves. Plunger seals, supported as a seal pack in a sleeve, are field installable over the plunger. A plunger to drive shim arrangement permits filed adjustment of the stroke.

1 . An intake header for a cryogenic pump having one or more pump heads comprising:
 a generally horizontally extending vessel having a liquid sump and a gas freeboard;   a liquid intake to the vessel and connected to a source of cryogenic liquid;   a gas outlet connected to the freeboard for venting gas ; and   one or more conduits, each conduit forming a suction corresponding to the one or more pump heads, each suction extending from the sump to a respective pump head for delivery of liquid in the sump to the pump head.   
     
     
         2 . The header of  claim 1  wherein two or more of the one or more suctions are spaced horizontally along the vessel for corresponding to the one or more pump heads 
     
     
         3 . The header of  claim 1  wherein each suction extends upwardly from the sump, through the liquid in the sump, through the gas in the freeboard and through an upper wall of the vessel for connection to the pump head. 
     
     
         4 . The header of  claim 1  further comprising a gas header along the upper wall of the vessel and in fluid communication with the freeboard for collecting gas therefrom. 
     
     
         5 . The header of  claim 1  wherein the vessel is cylindrical and having a horizontal axis, the liquid inlet being located at one end of the vessel at about the axis thereof. 
     
     
         6 . The header of  claim 1  further comprising a generally horizontally extending baffle in the sump. 
     
     
         7 . The header of  claim 6  wherein the baffle is a tray dividing the sump into an upper liquid-receiving portion above and a lower desaturated liquid portion therebelow, the tray having a weir for spilling liquid from the upper portion to the lower portion. 
     
     
         8 . The header of  claim 1  further comprising a distributor extending along the vessel for receiving liquid from the intake and having a plurality of openings for distributing the liquid along the horizontal extent of the vessel. 
     
     
         9 . The header of  claim 1  further comprising
 a generally horizontally extending tray dividing the sump into an upper liquid-receiving portion above and a lower desaturated liquid portion therebelow, the tray having a weir for spilling liquid from the upper portion to the lower portion; 
 a distributor extending along the vessel for receiving liquid from the intake and having a plurality of openings for distributing the liquid along the horizontal extent of the vessel, the distributor extending along the tray in the upper portion, the opening being located within the liquid in the upper portion. 
 
     
     
         10 . A pump head for a cryogenic pump having a cylinder, a cylinder head, and a plunger axially slidable in the cylinder for forming a chamber of variable axial extent between the cylinder head and the plunger, comprising:
 a liquid inlet to the chamber;   a discharge outlet through the cylinder head and having a discharge valve; and   an intake valve comprising
 a plurality of inlet passages spaced circumferentially-spaced about the cylinder head and situate between the liquid inlet and a periphery of the chamber, and 
 a ring-plate movable axially relative to the cylinder head between an open position away from the cylinder head for receiving liquid through the inlet passages to the chamber and a closed position engaged sealingly against the cylinder head to close the inlet passages. 
   
     
     
         11 . The pump head of  claim 10  wherein the cylinder head further comprises a cylindrical body having an annular valve seat formed thereabout for sealingly engaging the ring-plate in the closed position, the inlet passages formed about the valve seat. 
     
     
         12 . The pump head of  claim 10  wherein the cylinder head further comprises an annular inlet port about an outer circumference of the cylinder head, the annular inlet port in fluid communication with the liquid intake for distributing liquid about the cylinder head to the inlet passages. 
     
     
         13 . The pump head of  claim 10  further comprising a spring for biasing the ring-plate to the closed position. 
     
     
         14 . The pump head of  claim 10  wherein the cylinder head has a generally concave face, the plunger having a complementary protruding convex piston end face. 
     
     
         15 . The pump head of  claim 10  wherein the pump's cylinder comprises a cylindrical sleeve supported within a pump housing, the cylindrical sleeve and cylinder head retained axially within the pump housing. 
     
     
         16 . The pump head of  claim 15  wherein the pump housing has the liquid inlet formed therethrough, the annular Inlet port of the cylinder head being axially aligned with the fluid intake for receiving liquid from the liquid inlet. 
     
     
         17 . The pump head of  claim 10  wherein the pump's cylinder comprises a cylindrical sleeve supported within a pump housing, the cylindrical sleeve and cylinder head retained axially within the pump housing, further comprising a valve assembly, the valve assembly comprising the intake and discharge valves. 
     
     
         18 . The pump head of  claim 17  wherein the valve assembly is supported in the pump housing, aligned axially with the plunger, comprising:
 the cylinder head, having a cylindrical body co-axially aligned with the plunger and having an annular valve seat formed thereabout, 
 the ring-plate located in the chamber between the plunger and the cylinder head and movable axially towards the annular valve seat in the closed position for blocking the inlet passages and directing liquid to the discharge valve and axially away for the intake of fluid into the chamber, 
 the discharge valve comprising a plunger arranged within the discharge outlet through the cylinder head and forming an annular passage thereabout, the plunger supported in the discharge outlet and slidable between open and closed positions; and 
 a retaining nut to axially retain the valve assembly within the pump housing. 
 
     
     
         19 . The pump head of  claim 17  wherein the valve assembly further comprises:
 a discharge cover between the retaining nut and the cylinder head, the discharge cover comprising an annular plate having a plurality of circumferentially spaced discharge passages formed therein and in fluid communication with the annular passage of the discharge valve. 
 
     
     
         20 . The pump head of  claim 19  wherein the discharge cover further comprises a boss for slidably supporting the plunger in the discharge outlet. 
     
     
         21 . The pump head of  claim 10  wherein the plunger has a piston end operable in the chamber and a tail end adapted for connection to a drive, the tail end, the plunger supported for reciprocation in a pump housing further comprising:
 a cylindrical sleeve supported within the pump housing for forming the cylinder and having the piston end slidable therein; and 
 a seal assembly supported within the pump housing, the plunger's tail end sealably slidable therein. 
 
     
     
         22 . The pump head of  claim 21  wherein the plunger has a piston end operable in the chamber and a tail end adapted for connection to a drive, the tail end, the plunger supported for reciprocation in a pump housing further comprising:
 a cylindrical sleeve retained axially within the pump housing for forming the cylinder and having the piston end slidable therein; and 
 a seal assembly retained axially within the pump housing, the plunger's tail end sealably slidable therein. 
 
     
     
         23 . The pump head of  claim 22  wherein the seal assembly comprises:
 a seal pack for slidably sealing the tail end of the plunger; 
 a sleeve replaceably retained axially within the pump housing, the sleeve having a first lip for supporting the seal pack for axial removal from the pump housing; and 
 a packing nut for axially retaining the sleeve and retained seal pack within the pump housing. 
 
     
     
         24 . The pump head of  claim 10  wherein a tail end of the plunger is releaseably connected to a drive, further comprising one or more ring shims between the tail end of the plunger and the drive for adjusting a spacing of the plunger from the cylinder head. 
     
     
         25 . A sealing assembly for cryogenic pump, the pump having a cylinder and a cylinder head supported in a pump housing, and a plunger axially slidable in the cylinder for forming a chamber of variable axial extent between the cylinder head and a piston end of the plunger, the sealing assembly between a tail end of the plunger and the pump housing, the sealing assembly comprising:
 a sleeve replaceably retained axially within the pump housing and having a plunger bore therethrough for receiving the tail end of the plunger, the sleeve having a inboard lip and an open outboard end, the sleeve being axially removable from the pump housing;   an annular seal pack fit through the outboard end into the plunger bore and supported axially at the inboard lip, the seal pack sealing between the seal pack and the sleeve and between the seal pack and the plunger; and   a packing nut for axially releasably retaining the seal pack to the sleeve and the outboard end of the sleeve to the pump housing.   
     
     
         26 . The sealing assembly of  claim 25  wherein the seal pack comprises:
 a first rod seal adjacent the inboard lip; 
 a stack of lip seals; 
 a spacer between the first rod seal and stack of lip seals. 
 
     
     
         27 . The sealing assembly of  claim 26  wherein the first rod seal comprises a ring seal carrier supporting a compressor and a rod seal, the compressor and rod seal having complementary wedges for driving the rod seal radially inwardly and sealably against the plunger. 
     
     
         28 . A cryogenic pump comprising the pump head of  claim 10  and the header of  claim 1 .