VALVE ACTIVATION IN COMPRESSED-GAS ENERGY STORAGE AND RECOVERY SYSTEMS
In various embodiments, valve efficiency and reliability are enhanced via use of hydraulic or magnetic valve actuation, valves configured for increased actuation speed, and/or valves controlled to reduce collision forces during actuation.
1 . An energy storage and recovery system comprising:
a cylinder assembly (i) for, therewithin, at least one of compression of gas to store energy or expansion of gas to recover energy and (ii) having an interior compartment;
a valve for at least one of admitting fluid into the interior compartment or exhausting fluid from the interior compartment through a gated port, the valve comprising a valve member for occluding the gated port; and
for actuating the valve, an actuation mechanism comprising (i) an actuation cylinder having a lateral surface and first and second opposing end surfaces, (ii) a piston disposed within and dividing the actuation cylinder into first and second chambers, a difference in fluid pressure between the two chambers actuating the valve, (iii) within the first chamber, a first occludable orifice defined by the lateral surface and configured to be at least partially occluded by the piston during movement of the piston within the actuation cylinder, (iv) within the first chamber, a first fixed orifice configured to not be occluded by the piston during movement of the piston within the actuation cylinder, (v) within the second chamber, a second occludable orifice defined by the lateral surface and configured to be at least partially occluded by the piston during movement of the piston within the actuation cylinder, and (vi) within the second chamber, a second fixed orifice configured to not be occluded by the piston during movement of the piston within the actuation cylinder.
2 . The system of claim 1 , wherein the first fixed orifice is defined by the first end surface of the actuation cylinder and the second fixed orifice is defined by the second end surface of the actuation cylinder.
3 . The system of claim 1 , wherein the first occludable orifice is configured to be completely occluded by the piston when the piston is disposed proximate the first end surface.
4 . The system of claim 1 , wherein the second occludable orifice is configured to be completely occluded by the piston when the piston is disposed proximate the second end surface.
5 . The system of claim 1 , wherein a lateral dimension of at least a portion of the first occludable orifice varies as a function of distance from the first end surface.
6 . The system of claim 1 , wherein (i) a lateral dimension of a first portion of the first occludable orifice does not vary as a function of distance from the first end surface and (ii) a lateral dimension of a second portion of the first occludable orifice varies as a function of distance from the first end surface.
7 . The system of claim 1 , wherein a lateral boundary of at least a portion of the first occludable orifice has a shape defined by a function y(x)=C(V max 2 −2Ax) 1/2 , where C is a constant, V max is a velocity of the piston in the actuation cylinder when the first occludable orifice is not occluded, and A is a magnitude of deceleration of the piston in the actuation cylinder when the first occludable orifice is partially occluded.
8 . The system of claim 1 , further comprising a high-pressure fluid source selectively connectable to (i) both the first occludable orifice and the first fixed orifice or (ii) both the second occludable orifice and the second fixed orifice.
9 . The system of claim 8 , further comprising:
disposed within a connection between the high-pressure fluid source and the first fixed orifice, a first check valve configured to enable substantially unrestricted flow of fluid to the first fixed orifice when the first occludable orifice is at least partially occluded by the piston; and
disposed within a connection between the high-pressure fluid source and the second fixed orifice, a second check valve configured to enable substantially unrestricted flow of fluid to the second fixed orifice when the second occludable orifice is at least partially occluded by the piston.
10 . The system of claim 8 , further comprising a low-pressure fluid reservoir selectively connectable to (i) both the first occludable orifice and the first fixed orifice or (ii) both the second occludable orifice and the second fixed orifice.
11 . The system of claim 10 , further comprising a valve having different settings for connecting (i) the first occludable orifice and the first fixed orifice to the high-pressure fluid source, and the second occludable orifice and the second fixed orifice to the low-pressure fluid reservoir, (ii) the first occludable orifice and the first fixed orifice to the low-pressure fluid reservoir, and the second occludable orifice and the second fixed orifice to the high-pressure fluid source, or (iii) the first occludable orifice and the first fixed orifice to the second occludable orifice and the second fixed orifice.
12 . The system of claim 1 , further comprising a stem to which the valve member and the piston are mechanically connected.
13 . The system of claim 1 , wherein the cylinder assembly is configured to compress gas from an initial pressure to a final pressure, and further comprising a control system configured to:
pre-expand gas in the cylinder assembly to approximately the initial pressure;
following the pre-expansion, admit gas at the initial pressure into the cylinder assembly, the pre-expansion reducing coupling loss during the admission of gas;
compress the gas in the cylinder assembly to the final pressure;
complete a compression cycle by exhausting only a portion of the compressed gas out of the cylinder assembly; and
repeat the foregoing steps at least once, thereby performing at least one additional compression cycle,
wherein at least one of the gas admission or the gas exhaustion occurs through the gated port of the valve.
14 . The system of claim 1 , wherein the cylinder assembly is configured to expand gas from an initial pressure to a final pressure, and further comprising a control system configured to:
pre-compress gas in the cylinder assembly to approximately the initial pressure;
following the pre-compression, admit compressed gas at the initial pressure into the cylinder assembly, the pre-compression reducing coupling loss during the admission of compressed gas;
expand the gas in the cylinder assembly to the final pressure;
complete an expansion cycle by exhausting only a portion of the expanded gas out of the cylinder assembly; and
repeat the foregoing steps at least once, thereby performing at least one additional expansion cycle,
wherein at least one of the gas admission or the gas exhaustion occurs through the gated port of the valve.
15 . The system of claim 1 , further comprising:
a high-side component, selectively fluidly connected to the cylinder assembly, for at least one of (i) supplying gas to the cylinder assembly for expansion therein or (ii) accepting gas from the cylinder assembly after compression therein;
a low-side component, selectively fluidly connected to the cylinder assembly, for at least one of (i) supplying gas to the cylinder assembly for compression therein or (ii) accepting gas from the cylinder assembly after expansion therein; and
a control system for operating the cylinder assembly to perform at least one of (i) a pre-compression of gas therewithin prior to admission therein of gas for expansion, thereby reducing coupling loss between the cylinder assembly and the high-side component, or (ii) a pre-expansion of gas therewithin prior to admission therein of gas for compression, thereby reducing coupling loss between the cylinder assembly and the low-side component.
16 . The system of claim 15 , further comprising a sensor for sensing at least one of a temperature, a pressure, or a position of a boundary mechanism within the cylinder assembly to generate control information, the control system being responsive to the control information.
17 . The system of claim 16 , wherein the control system is configured to operate the cylinder assembly, during at least one of (i) pre-compression of gas therewithin or (ii) expansion of gas therewithin, based at least in part on control information generated during at least one of (i) a previous gas expansion within the cylinder assembly or (ii) a previous pre-compression of gas within the cylinder assembly.
18 . The system of claim 16 , wherein the control system is configured to operate the cylinder assembly, during at least one of (i) pre-expansion of gas therewithin or (ii) compression of gas therewithin, based at least in part on control information generated during at least one of (i) a previous gas compression within the cylinder assembly or (ii) a previous pre-expansion of gas within the cylinder assembly.
19 . The system of claim 15 , wherein the high-side component comprises a compressed-gas storage reservoir.
20 . The system of claim 15 , wherein the high-side component comprises a second cylinder assembly for at least one of compressing gas or expanding gas within a pressure range higher than a pressure range of operation of the cylinder assembly.
21 . The system of claim 15 , further comprising a second cylinder assembly for at least one of compressing gas or expanding gas within a pressure range higher than a pressure range of operation of the cylinder assembly, wherein the high-side component comprises a mid-pressure vessel for containing gas at a pressure within both of or between pressure ranges of operation of the cylinder assembly and the second cylinder assembly.
22 . The system of claim 15 , wherein the low-side component comprises a vent to atmosphere.
23 . The system of claim 15 , wherein the low-side component comprises a second cylinder assembly for at least one of compressing gas or expanding gas within a pressure range lower than a pressure range of operation of the cylinder assembly.
24 . The system of claim 15 , further comprising a second cylinder assembly for at least one of compressing gas or expanding gas within a pressure range lower than a pressure range of operation of the cylinder assembly, wherein the low-side component comprises a mid-pressure vessel for containing gas at a pressure within both of or between pressure ranges of operation of the cylinder assembly and the second cylinder assembly.