Apparatus and method for supercritical fluid extraction

A pumping system for pumping and pressurizing a fluid used in supercritical fluid extraction comprising:

• means connected to said pumping system for supercritical fluid extraction;
• a rotating cam means having a cam with displacement slopes and a cooperating cam follower which varies the volume within a pumping chamber whereby said pumping chamber has within it liquid under pressure;
• said pumping chamber including an inlet valve and an outlet valve;
• said rotating cam having a repressurization surface, a delivery surface, a transition surface, a depressurization surface and a refill surface positioned to be traversed by the said cam follower in that order;
• said depressurization surface having an initial displacement slope substantially equal to, but of the opposite sign of, the displacement slope of the final part of the delivery surface;
• said transition surface being rounded sufficiently to allow closing of the said outlet valve without damage and to keep Hertzian contact forces between the cam and cam follower low enough to prevent deformation;
• said depressurization surface being shaped to produce a continuously increasing linear velocity of the cam follower with respect to the cam rotation speed until the cam follower reaches the said refill surface, at which time the velocity the cam follower moves with a more constant linear velocity with respect to the cam rotation speed as it runs along the refill surface, whereby the fluid is pressurized by a maximum pressure by the pumping system and transferred to a heating means that converts said pressurized fluid to supercritical fluid.