Flow control valve with erosion protection

A choke for a flow control valve, the choke comprising:

• a housing having a first orifice and a second orifice each extending through the housing, the first orifice being axially spaced from the second orifice;
• a choke sleeve disposed within the housing, the choke sleeve having:
• an opening extending through the choke sleeve and aligned with the first orifice of the housing;
• and
• a plurality of choking orifices extending through the choke sleeve and spaced axially from the opening, wherein each choking orifice of the plurality of choking orifices is radially aligned with the second orifice of the housing;
• a piston disposed within the choke sleeve, the piston including a main body and a retainer coupled to an end of the main body, and the piston slidable relative to the choke sleeve to selectively cover and uncover one or more of the plurality of choking orifices of the choke sleeve and the opening of the choke sleeve, wherein:
• in response to the piston being moved to uncover select choking orifices, fluid is permitted to flow from outside the housing, through the second orifice of the housing, and through the select choking orifices;
• in response to the piston being moved to further uncover the opening of the choke sleeve, fluid is permitted to flow from outside the housing through the first orifice and the opening of the choke sleeve;
• and
• in a given position of the piston, fluid communication is established via the one or more of the plurality of choking orifices;
• a flow restriction ring positioned at least partially annularly between the piston and the choke sleeve and configured to prevent or restrict fluid flow through a leakage gap formed annularly between the choke sleeve and the piston, wherein the flow restriction ring is disposed about the retainer;
• and
• a gap radially between the flow restriction ring and an outer surface of the piston when the flow restriction ring is in a free state, wherein as the piston moves toward a closed position in use and the flow restriction ring moves adjacent to or in contact with a choke seal, the flow restriction ring collapses into the gap and reduces in diameter.

A method of operating a flow control valve, the flow control valve comprising a housing having a first orifice and a second orifice each extending through the housing, the first orifice being axially spaced from the second orifice, a choke sleeve disposed within the housing, the choke sleeve having an opening extending through the choke sleeve and aligned with the first orifice of the housing and a plurality of choking orifices extending through the choke sleeve and spaced axially from the opening, wherein each choking orifice of the plurality of choking orifices is radially aligned with the second orifice of the housing, and a piston disposed within the choke sleeve, the piston slidable relative to the choke sleeve, and an internal surface of the piston at least partially defining a flow passage through the flow control valve, the method comprising:

• sliding the piston relative to the choke sleeve to selectively uncover one or more select choking orifices of the plurality of choking orifices of the choke sleeve, thereby permitting fluid communication between an outside of the housing and the flow passage through the second orifice of the housing and the select choking orifices;
• inhibiting leakage flow through a leakage gap formed annularly between the choke sleeve and the piston, wherein inhibiting leakage flow through the leakage gap includes slowing a flow rate of the leakage flow by passing the leakage flow through narrow flow passages formed between the piston and a flow restriction ring disposed about the piston and in contact with the choke sleeve;
• and collapsing the flow restriction ring to reduce a diameter of the flow restriction ring as the piston slides toward a closed position.