High frequency pressure swing adsorption
AssigneeQuestor Industries Inc.
InventorBowie G. Keefer
Life of this patent
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Abstract
Pressure swing adsorption separation of a feed gas mixture, to obtain a purified product gas of the less strongly adsorbed fraction of the feed gas mixture, is performed in a plurality of preferably an even number of adsorbent beds, with each adsorbent bed communicating at its product end directly to a variable volume expansion chamber, and at its feed end by directional valves to a feed compressor and an exhaust vacuum pump. For high frequency operation of the pressure swing adsorption cycle, a high surface area layered support is used for the adsorbent. The compressor and vacuum pump pistons may be integrated with the cycle, reciprocating at twice the cycle frequency. Alternative configurations of the layered adsorbent beds are disclosed.
Claims76
Process for separating first and second components of a feed gas mixture, the first component being more readily adsorbed over an adsorbent material under increase of pressure relative to the second component, 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 defining a cycle period, the process comprising the steps of:
- providing for the process of number “N” of substantially similar adsorbent beds of the adsorbent material, with said adsorbent beds having first and second ends;
- providing a variable volume expansion chamber for each adsorbent bed and in communication with the second end of each adsorbent bed;
- and
- performing in each adsorbent bed the sequentially repeated steps within the cycle period of:
- a. supplying a flow of the feed gas mixture to the first end of the adsorbent bed during a feed time interval commencing when the pressure within the adsorbent bed is at a first intermediate pressure between the lower pressure and the higher pressure, pressurizing the adsorbent bed to substantially the higher pressure, and then continuing the flow of feed gas mixture at substantially higher pressure while withdrawing gas enriched in the second component from the second end of the adsorbent bed, and delivering gas enriched in the second component as a light product gas at a light product delivery pressure,
- b. withdrawing a flow of gas enriched in the second component as light reflux gas from the second end of the adsorbent bed into the expansion chamber during a cocurrent blowdown time interval, and expanding the volume of the expansion chamber so as to depressurize the adsorbent bed from the higher pressure toward a second intermediate pressure between the higher pressure and the lower pressure,
- c. withdrawing a flow of gas enriched in the first component from the first end of the adsorbent bed during an exhaust time interval, so as to depressurize the adsorbent bed from the second intermediate pressure to the lower pressure, and then contracting the volume of the expansion chamber so as to supply the light reflux gas from the expansion chamber to the second end of the adsorbent bed to purge the adsorbent bed at substantially the lower pressure while continuing to withdraw gas enriched in the first component as a heavy product gas, and
- d. further contracting the expansion chamber so as to supply the light reflux gas from the expansion chamber to the second end of the adsorbent bed during a light reflux pressurization time interval, to increase the pressure of the adsorbent bed from substantially the lower pressure to the first intermediate pressure.
Apparatus for separating first and second components of a feed gas mixture, the first component being more readily adsorbed over an adsorbent material under increase of pressure relative to the second component, such that a gas mixture of the first and second components contacting the adsorbent material is relatively enriched in the first component at a higher pressure when the pressure is cycled between the lower and higher pressures at a cyclic frequency 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. a feed valve means and an exhaust valve means connected to the first end of each adsorbent bed,
- c. valve actuation means to actuate the feed valve means and the exhaust valve means, so that at any instant one of the feed or exhaust valve means may be open with the other closed or else both of the feed and exhaust valve means are closed,
- d. feed supply means to introduce the feed gas mixture to the feed valve means at a feed pressure,
- e. exhaust means to remove gas enriched in the first component from the exhaust valve means;
- f. 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;
- g. a variable volume expansion chamber communicating with the second end of each adsorbent bed;
- and
- h. expansion chamber cycling means to vary the volume of the expansion chamber between minimum and maximum volumes of the expansion chamber at the cyclic frequency, with the minimum volume being reached at a top dead centre time within the cycle period, and the maximum volume being reached at a bottom dead centre time within the cycle period;
- and the valve actuation means cooperates with the expansion chamber cycling means so that for each adsorbent bed:
- i. the valve actuation means opens the feed valve means when the expansion chamber is approaching its minimum volume, when the pressure in the adsorbent bed is less than the higher pressure keeps the feed valve means open during a feed time interval while the expansion chamber cycling means brings the volume of the expansion chamber past its minimum volume and the pressure in the adsorbent bed has risen to substantially the higher pressure, and closes the feed valve following the top dead centre time by a feed phase lag interval,
- ii. the valve actuation means opens the exhaust valve means when the expansion chamber is approaching its maximum volume, when the pressure in the adsorbent bed is greater than the minimum pressure keeps the exhaust valve means open during an exhaust time interval while the expansion chamber cycling means brings the volume of the expansion chamber past its maximum volume and the pressure in the adsorbent bed has dropped to substantially the lower pressure, and closes the exhaust valve means following the top dead centre time by an exhaust phase lag interval, and
- iii. the valve actuation means keeps both the feed and exhaust valve means closed during a cocurrent blowdown time interval while the pressure in the adsorbent bed is decreasing between the feed and exhaust time intervals, and during a light reflux pressurization time interval while the pressure in the adsorbent bed is increasing between the exhaust and subsequent feed time intervals, with the cycle period being equal to the sum of the feed, cocurrent blowdown, exhaust and light reflux pressurization time intervals.
Apparatus for separating first and second components of a feed gas mixture, the first component being more readily adsorbed over an adsorbent material under increase of pressure relative to the second component, 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 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. a feed valve means and an exhaust valve means connected to the first end of each adsorbent bed,
- c. valve actuation means to actuate the feed valve means and the exhaust valve means, so that at any instant one of the feed or exhaust valve means may be open with the other closed or else both of the feed and exhaust valve means are closed,
- d. feed supply means to introduce the feed gas mixture to the feed valve means at a feed pressure,
- e. exhaust means to remove gas enriched in the first component from the exhaust valve means,
- f. 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,
- g. a light reflux rotary distributor valve connected in parallel to the second ends of the adsorbent beds, the 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 elements, the stator being a bed port element having N bed ports each communicating to the second end of one of the N adsorbent beds, and the rotor being a function port element having a plurality of function ports in pairs connected within the rotor by light reflux channels, with the bed ports spaced apart by equal angular separation between adjacent ports, with the function ports and bed ports at the same radial 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, and with fluid sealing sliding contact between the stator and rotor of the distributor valve;
- and
- h. drive means to establish rotation of the rotor.
Adsorber element for contacting an adsorbent material to a fluid mixture, the adsorber element being formed from layered thin and flexible adsorbent sheets, the sheets being the adsorbent material with a reinforcement material, with spacers between the sheets to establish flow channels in a flow direction tangential to the sheets and between adjacent pairs of sheets, the adsorber elements having first and second ends defining a flow path with a nominal flow direction through the adsorber element, and with the spacers provided as alternatingly first and second spacer patterns, the spacer patterns defining the substantially radial flow direction, and the first and second spacer patterns being oppositely skewed with respect to the nominal flow direction so as to provide multiple oblique crossovers of the spacer patterns, and thus to stabilize the adsorber element against deflections that would degrade the uniformity of the flow channels.
Dependencies are inferred from the claim text.