Very low NPSH cryogenic pump and mobile LNG station

An inclined or vertical reciprocating pump for pumping low NPSH cryogenic liquids to about medium or high pressures, the pump comprising:

• cylinder means,
• piston means reciprocally movable within said cylinder means,
• liquid outlet valve means mounted in a closure attached to the discharge end of said cylinder means,
• combination valve means for liquid inlet and vapor outlet into and out of said cylinder means,
• piston rod means reciprocally movable generally along the axis of said cylinder means in a direction toward said outlet valve means and in a reciprocal direction causing a compression stroke and then an intake stroke by said piston means to which said rod means is linked, said rod means and said piston means loosely connected so that they form said combination valve means,
• said cylinder means, said outlet valve means and said closure, said combination valve means and said the compression face of said reciprocally moving piston means defining a pumping chamber,
• said cylinder means, said rod means, said combination valve means, and the intake face of said reciprocally moving piston defining part of an annular intake chamber in which said combination valve means is in the lower portion,
• conduit or conduits having one end in communication with said intake chamber or extensions thereof and the other end in communication with said compression chamber, said conduit or conduits located generally above said compression chamber and are open or closed as determined by the action of said combination valve means,
• drive means attached to the upper end of said rod means for providing a reciprocating motion causing said intake stroke and said compression stroke by said piston means,
• pressure seal means located between said cylinder means and said piston means so as to reduce leakage between said compression chamber and said intake chamber during said compression stroke,
• said combination valve means operatively associated with said rod means and said piston means in a lost motion type arrangement, whereby said combination valve means is mechanically caused to open during said intake stroke and to close during said compression stroke,
• said combination valve means and said intake chamber located above said compression chamber so that when said combination valve means is open, either said liquid can flow downwardly from said intake chamber into said compression chamber or said vapor can flow upwardly from said compression chamber into said intake chamber as influenced by gravity, or the enlargement of said compression chamber and the contraction of said intake chamber or other reasons and,
• said outlet valve means being a check valve type responsive to the flow therethrough of said liquid caused by said compression stroke or by the lack of flow caused by said intake stroke,
• the improvement comprising:
• (a) said piston means consisting of a first piston means and a second piston means,
• (b) said movable combination valve means consisting of a first combination valve means and a second combination valve means,
• (c) said first combination valve means operatively associated with said piston rod means and said first piston means, in a lost motion type arrangement, whereby said first combination valve means is mechanically caused to open during said intake stroke and to close during said compression stroke,
• (d) said second combination valve means operatively associated with said first piston means and said second piston means, in a lost motion type arrangement, whereby said second combination valve means are mechanically caused to open during said intake stroke and to close during said compression stroke and
• (e) said conduit or conduits consisting of a first conduit and a second conduit;
• whereby once both said combination valve means are open, said liquid can flow into said compression chamber without said flow being impeded by the flow of vapor caused by the displacement of said vapor by said entering liquid, as well as vapor created from other reasons, both said first and said second combination valve means alternately opening and closing said first conduit and said second conduit to flow, said first inlet valve means closing said first conduit to flow when said rod means moves in said compression stroke in a direction towards and contacts said first piston means, said second combination valve means closing said third conduit to flow as said rod means and said first piston means continues said compression stroke, causing said first piston means to contact said second piston means, said first and second piston means each having said conduit therethrough generally co-axial with said cylinder.

The method of causing a reciprocating pump to fill its pumping chamber with a cryogenic liquid from a source of said liquid under very low NPSH conditions comprising the steps of:

• (a) mounting said pump in a vertical or inclined position,
• (b) mechanically opening a first and a second intake valve,
• (c) providing an upwardly inclined path or conduit through said opened first intake valve preferentially arranged for cryogenic vapor to exit said pumping chamber and said pump and return to said source,
• (d) providing a downwardly inclined path or conduit preferentially arranged for said liquid to leave said source and enter said pump at a lower elevation than said upwardly inclined path and to enter said pumping chamber through said mechanically opened second intake valve,
• whereby said pump both empties said pumping chamber of said vapor and fills said pumping chamber with said liquid to be pumped by utilizing the effects of gravity.

The method of utilizing for a vehicle a first liquid, a cryogenic fuel used both as as a power source for an engine and as a source of refrigeration, and a second liquid, an expendable cryogen used as a source of refrigeration, comprising the steps of:

• (a) mounting on said vehicle a first tank for storing said first liquid and a second tank for storing said second liquid, said vehicle containing both said engine capable of utilizing the vapor phase of said first liquid as said fuel and a cooling system using said second liquid as an expendable cryogen as refrigeration source for cooling a portion of said vehicle,
• (b) providing a system to pressurize said first liquid,
• (c) connecting the outlet of said first tank and said pressurizing system to a vaporizing system, containing a phase change material, for warming said first liquid and cooling said phase change material,
• (d) operating said engine and supplying the now pressurized, warmed and vaporized first liquid as said fuel to said engine,
• (e) connecting said phase change material to said vehicle's said cooling system,
• (f) connecting said second tank to said cooling system,
• (g) operating said cooling system so as to provide cooling to said vehicle, utilizing both the cooling available from said second liquid and the cooling available from said phase change material,
• whereby the pressurized vapor phase of said first liquid is supplied to said vehicle's engine, and cooling resulting from said first liquid's warming and vaporization is subsequently utilized for cooling of said vehicle,
• and whereby the cooling resulting from said first liquid's vaporization and warming is decoupled timewise from that cooling's use in cooling of said vehicle,
• and whereby the amount of said second liquid required for cooling of said vehicle is reduced by the amount of cooling obtained from said first liquid's vaporization and warming.