Flow rate controller for high flow rates and high pressure drops

A pressure-independent flow rate controller assembly, comprising:

• a flow inlet and a flow outlet through which fluid flows, wherein fluid pressure at the flow inlet is an inlet pressure (P1) and the fluid pressure at the flow outlet is an outlet pressure (P3);
• an interior chamber with first and second chamber portions and a balance channel adjacent to the second chamber portion;
• an intermediate passageway interconnecting the flow outlet to the first chamber portion;
• a spring-biased piston slideably disposed in the interior chamber and having first and second piston portions axially spaced apart from each other by an intermediate space therebetween, wherein fluid is blocked from moving relative to the piston between the first chamber portion and the intermediate space and from moving relative to the piston between the intermediate space and the second chamber portion, and wherein the pressure of the fluid in the intermediate space being substantially at the outlet pressure (P3);
• a first throttling assembly having a first throttling seat with a throttling channel that receives fluid substantially at the inlet pressure (P1), the throttling channel configured to direct fluid toward the first chamber portion, and the first throttling assembly having a first throttling member coupled to the first chamber portion and to the piston, the first throttling member having an end portion shaped to mate with the throttling seat, the end portion having a first area against which fluid at the inlet pressure (P1) acts, the first throttling member being movable relative to the throttling seat to allow the fluid to flow into the first chamber portion, wherein fluid in the first chamber portion and in the intermediate passageway is at an intermediate pressure (P2) less than the inlet pressure (P1) and greater than the outlet pressure (P3), and wherein the intermediate passageway is in fluid communication with the second chamber portion and fluid in the second chamber portion is at the intermediate pressure (P2);
• a balance member coupled to the piston and having a fluid-acting surface with an area substantially equal to the first area of the end portion of the first throttling member, wherein fluid at the inlet pressure (P1) acts on the fluid acting surface to balance the fluid pressure acting on the end portion of the first throttling member;
• an adjustable restriction assembly configured to allow the fluid from the intermediate passageway to flow at a selected constant flow rate toward the flow outlet at the outlet pressure (P3), wherein the selected constant flow rate is independent of a pressure differential between the outlet pressure (P3) and the inlet pressure (P1);
• and
• a second throttling assembly configured to receive the flow of fluid from the adjustable restriction assembly, the second throttling assembly having second throttling member coupled to a spring biased piston and having a second throttling seat configured to receive the flow of fluid from the adjustable restriction assembly in an under-then-over trim configuration.

A constant rate flow rate controller, comprising:

• a flow inlet and a flow outlet through which fluid flows, wherein fluid pressure at the flow inlet is an inlet pressure (P1) and the fluid pressure at the flow outlet is an outlet pressure (P3);
• an interior chamber with first and second chamber portions and a balance channel adjacent to the second chamber portion, the first and second chamber portions being separated by an annular intermediate space containing fluid at the outlet pressure (P3), the first and second chamber portions containing a portion of the fluid at an intermediate pressure (P2), wherein the intermediate pressure (P2) is less than the inlet pressure (P1) and greater than the outlet pressure (P3), wherein fluid is blocked from moving past the first piston portion between the first chamber portion and the annular intermediate space, and wherein fluid is blocked from moving between the annular intermediate space and the second chamber portion;
• a piston slideably disposed in the interior chamber and having first and second piston portions axially spaced apart from each other, the piston having an internal area containing fluid at the intermediate pressure (P2);
• an annular piston biasing member in the annular intermediate space and having an outer diameter (D1) and an inner diameter (D2), and the piston biasing member defines an annular area between D1 and D2, the annular piston biasing member balancing the annular areas between D1 and D2 against the forces of the intermediate pressure (P2) acting on the piston and the opposing forces of the outlet pressure (P3) in the internal area acting against the piston;
• a throttling seat that receives the fluid from the flow inlet substantially at the inlet pressure (P1), and the throttling seat directs fluid to the first chamber portion;
• a throttling member moveably disposed in the first chamber portion and connected to the piston, the throttling member having an end portion shaped to mate with a portion of the throttling seat, the end portion having a first area against which the fluid acts substantially at the inlet pressure (P1), the throttling member being movable relative to the throttling seat, the throttling member allows the fluid to flow into the first chamber portion at the intermediate pressure (P2);
• a balance member coupled to the piston and having a portion adjacent to the balance channel and having an fluid-acting surface with an area substantially equal to the first area of the end portion of the throttling member, the balance channel containing a portion of the fluid at the inlet pressure (P1) that acts on the fluid acting surface and balances opposing the fluid pressure at the inlet pressure (P1) acting on the end portion of the throttling member;
• and
• an adjustable restriction assembly configured to allow the fluid from the interior chamber to flow at a selected constant flow rate toward the outlet at the outlet pressure (P3), wherein the selected constant flow rate is independent of a pressure differential between the outlet pressure (P3) and the inlet pressure (P1) because of the pressure balance across the area bounded by D1-D2.

A flow rate controller, comprising:

• a flow inlet and a flow outlet through which fluid flows, wherein fluid pressure at the flow inlet is an inlet pressure (P1) and the fluid pressure at the flow outlet is an outlet pressure (P3);
• an interior chamber with first and second chamber portions and a balance channel adjacent to the second chamber portion;
• a spring-biased piston slideably disposed in the interior chamber and having first and second piston portions axially spaced apart from each other by an intermediate space therebetween, wherein fluid is blocked from moving relative to the piston between the first chamber portion and an intermediate space from moving relative to the piston between the intermediate space and the second chamber portion, and wherein the pressure of the fluid in the intermediate space being substantially at the outlet pressure (P3);
• a first throttling assembly having a first throttling seat with a throttling channel that receives fluid substantially at the inlet pressure (P1), the throttling channel configured to direct fluid toward the first chamber portion, and the first throttling assembly having a first throttling member coupled to the first chamber portion and to the piston, the first throttling member having an end portion shaped to mate with the throttling seat, the end portion having a first area against which fluid at the inlet pressure (P1) acts, the first throttling member being movable relative to the throttling seat to allow the fluid to flow into the first chamber portion, wherein fluid in the first chamber portion and in the intermediate passageway is at an intermediate pressure (P2) less than the inlet pressure (P1) and greater than the outlet pressure (P3), and wherein the intermediate passageway is in fluid communication with the second chamber portion and fluid in the second chamber portion is at the intermediate pressure (P2);
• a balance member coupled to the piston and having a fluid-acting surface with an area substantially equal to the first area of the end portion of the first throttling member, wherein fluid at the inlet pressure (P1) acts on the fluid acting surface to balance the fluid pressure acting on the end portion of the first throttling member;
• and
• an adjustable restriction assembly configured to allow the fluid from the interior chamber to flow at a selected constant flow rate toward the flow outlet at the outlet pressure (P3), wherein the selected constant flow rate is independent of a pressure differential between the outlet pressure (P3) and the inlet pressure (P1).