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US 6,063,161 AGranted
Flow regulated pressure swing adsorption system
AssigneeSoFinoy Societte Financiere d'Innovation Inc.
InventorsBowie Gordon Keefer, David George Doman
Life of this patent
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Abstract
Pressure swing adsorption (PSA) separation of a gas mixture is performed in an apparatus with a plurality of adsorbent beds. The invention provides rotary multiport distributor valves to control the timing sequence of the PSA cycle steps between the beds, with flow controls cooperating with the rotary distributor valves to control the volume rates of gas flows to and from the adsorbent beds in blowdown, purge, equalization and repressurization steps.
Claims46
Process for separating first and second components of a feed gas mixture, the first component being more readily adsorbed under increase of pressure relative to the second component which is less readily adsorbed under increase of pressure over an adsorbent material, such that a gas mixture of the first and second components contacting the adsorbent material is relatively enriched in the first component at a lower pressure and is relatively enriched in the second component at a higher pressure when the pressure is cycled between the lower and higher pressures at a cyclic frequency of the process defining a cycle period;
- providing for the process a number "N" of substantially similar adsorbent beds of the adsorbent material, with said adsorbent beds having first and second ends;
- and further providing for the process a first rotary distributor valve connected in parallel to the first ends of the adsorbent beds and a second rotary distributor valve connected in parallel to the second ends of the adsorbent beds, with flow controls cooperating with the first and second distributor valves;
- introducing the feed gas mixture at substantially the higher pressure to the first distributor valve;
- and rotating the first and second distributor valves so as to perform in each adsorbent bed the sequentially repeated steps within the cycle period of:
- (A) supplying a flow of the feed gas mixture at the higher pressure through the first distributor valve to the first end of the adsorbent bed during a feed time interval, withdrawing gas enriched in the second component from the second end of the adsorbent bed, and delivering a portion of the gas enriched in the second component as a light product gas,
- (B) withdrawing a flow of gas enriched in the second component as light reflux gas from the second end of the adsorbent bed through the second distributor valve, so as to depressurize the adsorbent bed from the higher pressure toward an equalization pressure less than the higher pressure, while controlling the flow so that the pressure in the bed approaches the equalization pressure within an equalization time interval,
- (C) withdrawing a flow of light reflux gas enriched in the second component from the second end of the adsorbent bed through the second distributor valve, so as to depressurize the adsorbent bed from approximately the equalization pressure to an intermediate pressure less than the equalization pressure and greater than the lower pressure, while controlling the flow so that the pressure in the bed reaches approximately the intermediate pressure within a cocurrent blowdown time interval,
- (D) withdrawing a flow of gas enriched in the first component from the first end of the adsorbent bed through the first distributor valve, so as to depressurize the adsorbent bed from approximately the intermediate pressure to approach the lower pressure, while controlling the flow so that the pressure in the bed approaches the lower pressure within a countercurrent blowdown time interval,
- (E) returning a flow of light reflux gas enriched in the second component from the second distributor valve to the second end of the adsorbent bed at substantially the lower pressure, while withdrawing gas enriched in the first component from the first end of the adsorbent bed and through the first distributor valve over a purge time interval, said flow of gas enriched in the second component from the second distributor valve being withdrawn from another of the adsorbent beds which is undergoing cocurrent blowdown step (C) of the process,
- (F) returning a flow of light reflux gas enriched in the second component from the second distributor valve to the bed, so as to repressurize the adsorbent bed from approximately the lower pressure to approach the equalization pressure, while controlling the flow so that the pressure in the bed approaches the equalization pressure within an equalization time interval, said flow of gas enriched in the second component from the second distributor valve being withdrawn from another of the adsorbent beds which is undergoing equalization step (B) of the process,
- (G) admitting gas to the adsorbent bed, so as to further repressurize the adsorbent bed from the equalization pressure toward the higher pressure, while controlling the flow so that the pressure in the bed approaches the higher pressure within a repressurization time interval,
- (H) cyclically repeating steps (A) to (G).
9 more elements
Apparatus for separating first and second components of a feed gas mixture, the first component being more readily adsorbed under increase of pressure relative to the second component which is less readily adsorbed under increase of pressure over an adsorbent material, such that a gas mixture of the first and second components contacting the adsorbent material is relatively enriched in the first component at a lower pressure and is relatively enriched in the second component at a higher pressure when the pressure is cycled between the lower and higher pressures at a cyclic frequency of the process defining a cycle period, the apparatus including
- (a) a number "N" of substantially similar adsorbent beds of the adsorbent material, with said adsorbent beds having first and second ends defining a flow path through the adsorbent material;
- (b) light product delivery means to deliver a light product flow of gas enriched in the second component from the second ends of the adsorbent beds;
- (c) a first rotary distributor valve connected in parallel to the first ends of the adsorbent beds;
- the first distributor valve having a stator and a rotor rotatable about an axis;
- the stator and rotor comprising a pair of relatively rotating valve elements, the valve elements being engaged in fluid sealing sliding contact in a valve surface, the valve surface being a surface of revolution coaxial to the axis, each of the valve elements having a plurality of ports to the valve surface and in sequential sliding registration with the ports in the valve surface of the other valve element through the relative rotation of the valve elements;
- one of the valve elements being a first bed port element having N first bed ports each communicating to the first end of one of the N adsorbent beds;
- and the other valve element being a first function port element having a plurality of first function ports including a feed port, a countercurrent blowdown port and a purge exhaust port;
- with the bed ports spaced apart by equal angular separation between adjacent ports;
- and with the first function ports and first bed ports at the same radial and axial position on the valve surface so that each first function port is opened in sequence to each of the N first bed ports by relative rotation of the valve elements;
- (d) a second rotary distributor valve connected in parallel to the second ends of the adsorbent beds and cooperating with the first distributor valve;
- the second distributor valve having a stator and a rotor rotatable about an axis;
- the stator and rotor comprising a pair of relatively rotating valve elements, the valve elements being engaged in fluid sealing sliding contact in a valve surface, the valve surface being a surface of revolution coaxial to the axis, each of the valve elements having a plurality of ports to the valve surface and in sequential sliding registration with the ports in the valve surface of the other valve element through the relative rotation of the valve elements;
- one of the valve elements being a second bed port element having N second bed ports each communicating to the second end of one of the N adsorbent beds;
- and the other valve element being a second function port element having a plurality of second function ports including a plurality of light reflux withdrawal ports and light reflux return ports, with each light reflux return port communicating through the second function element to a light reflux withdrawal port;
- with the bed ports spaced apart by equal angular separation between adjacent ports;
- and with the function ports and bed ports at the same radial and axial position on the valve surface so that each function port is opened in sequence to each of the N bed ports by relative rotation of the valve elements;
- (e) drive means to establish rotation of the rotors, and hence relative rotation of the bed port elements and the function port elements of the first and second distributor valves, with a phase relation between the rotation of the rotors and angular spacing of the function ports of the first and second distributor valves so as to establish for each adsorbent bed communicating to corresponding first and second bed ports the following sequential and cyclically repeated steps at a cycle frequency for those bed ports:
- (i) the first bed port is open to the feed port, while light product gas is delivered by the light product delivery means,
- (ii) the second bed port is open to a light reflux withdrawal port,
- (iii) the first bed port is open to the countercurrent blowdown port,
- (iv) the first bed port is open to the purge exhaust port, while the second bed port is open to a light reflux return port;
- (f) countercurrent blowdown flow control means cooperating with the first distributor valve;
- (g) light reflux flow control means cooperating with the second distributor valve;
- (h) feed supply means to introduce the feed gas mixture to the feed port of the first distributor valve at substantially the higher pressure;
- and
- (i) exhaust means to remove gas enriched in the first component from the purge exhaust port of the first distributor valve.
23 more elements
Dependencies are inferred from the claim text.