The invention relates to a recirculation device for a gas of a process device, said recirculation device comprising a recirculation pump, wherein the recirculation pump is a side channel pump.

A system for delivering pressurized fracking fluid to a well includes a high-pressure pump pumping proppant-free fluid, and a double-piston pressure transfer arrangement for transferring pressure from the proppant-free fluid to a fracking fluid. The pressure transfer arrangement includes first and second cylinder assemblies, each having a piston in sliding engagement within a first hollow cylinder so as to define first and second chambers of the first cylinder and third and fourth chambers of the second cylinder. A piston rod interconnects the pistons. A flow selector alternately directs high-pressure proppant-free fluid to the first chamber and the third chamber so as to act on the pistons, thereby applying pressure to fracking fluid within the second and fourth chambers, respectively, for delivery to the well in alternate power strokes. The faces of the pistons facing the first and third chambers have a smaller effective surface area than the faces towards the second and fourth chambers such that pressure in the fracking fluid remains lower than pressure in the proppant-free fluid.

A system for delivering pressurized fracking fluid to a well includes a high-pressure pump pumping proppant-free fluid, and a double-piston pressure transfer arrangement for transferring pressure from the proppant-free fluid to a fracking fluid. The pressure transfer arrangement includes first and second cylinder assemblies, each having a piston in sliding engagement within a first hollow cylinder so as to define first and second chambers of the first cylinder and third and fourth chambers of the second cylinder. A piston rod interconnects the pistons. A flow selector alternately directs high-pressure proppant-free fluid to the first chamber and the third chamber so as to act on the pistons, thereby applying pressure to fracking fluid within the second and fourth chambers, respectively, for delivery to the well in alternate power strokes. The faces of the pistons facing the first and third chambers have a smaller effective surface area than the faces towards the second and fourth chambers such that pressure in the fracking fluid remains lower than pressure in the proppant-free fluid.

The invention relates to a recirculation device for a gas of a process device, said recirculation device comprising a recirculation pump, wherein the recirculation pump is a side channel pump.

An example apparatus includes a housing including an inlet and an outlet. The example apparatus also includes a rotor defining a bore. The rotor is disposed in the housing. The example apparatus further includes a piston disposed in the bore. A motor is operatively coupled to the rotor to rotate the rotor from a first position to a second position. The bore is to be in fluid communication with the inlet and the outlet when the rotor is in the second position.

An example apparatus includes a housing including an inlet and an outlet. The example apparatus also includes a rotor defining a bore. The rotor is disposed in the housing. The example apparatus further includes a piston disposed in the bore. A motor is operatively coupled to the rotor to rotate the rotor from a first position to a second position. The bore is to be in fluid communication with the inlet and the outlet when the rotor is in the second position.

An apparatus for pumping a fluid from a fluid inlet to a fluid outlet is disclosed. The apparatus comprises: a spool axially movable within a cavity, wherein a first chamber is located at a first axial end of the cavity and a second chamber is located at a second axial end of the cavity, wherein the volume of the first chamber and the second chamber varies depending upon the axial position of the spool within the cavity; a valve movable between a first position and a second position, wherein in the first position the valve is configured to convey fluid from the fluid inlet to the first chamber and from the second chamber to the fluid outlet, and in the second position the valve is configured to convey fluid from the fluid inlet to the second chamber and from the first chamber to the fluid outlet.

An apparatus for pumping a fluid from a fluid inlet to a fluid outlet is disclosed. The apparatus comprises: a spool axially movable within a cavity, wherein a first chamber is located at a first axial end of the cavity and a second chamber is located at a second axial end of the cavity, wherein the volume of the first chamber and the second chamber varies depending upon the axial position of the spool within the cavity; a valve movable between a first position and a second position, wherein in the first position the valve is configured to convey fluid from the fluid inlet to the first chamber and from the second chamber to the fluid outlet, and in the second position the valve is configured to convey fluid from the fluid inlet to the second chamber and from the first chamber to the fluid outlet.

An example apparatus includes a housing including an inlet and an outlet. The example apparatus also includes a rotor defining a bore. The rotor is disposed in the housing. The example apparatus further includes a piston disposed in the bore. A motor is operatively coupled to the rotor to rotate the rotor from a first position to a second position. The bore is to be in fluid communication with the inlet and the outlet when the rotor is in the second position.

An example apparatus includes a housing including an inlet and an outlet. The example apparatus also includes a rotor defining a bore. The rotor is disposed in the housing. The example apparatus further includes a piston disposed in the bore. A motor is operatively coupled to the rotor to rotate the rotor from a first position to a second position. The bore is to be in fluid communication with the inlet and the outlet when the rotor is in the second position.