Thermally coupled pressure swing adsorption
OwnerBowie G. Keeferinventor
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Abstract
Pressure swing adsorption separation of a gas mixture is performed in an apparatus with a plurality of adsorbent beds cooperating to exchange energy from an adsorbent bed undergoing a depressurization step to an adsorbent bed undergoing a pressurization step, and with provision for thermal coupling in order to improve process efficiency. Thermal coupling is provided as heating to augment expansion energy recovery, and as a temperature gradient imposed in adsorbent beds to provide the function of a thermal regenerator in a regenerative thermodynamic cycle. The invention provides improved techniques for recovery of expansion energy in pressure swing adsorption, and for direct application of thermal energy to power pressure swing adsorption processes.
Claims43
A process for separating first and second components of a 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 defining a cycle period;
- providing for the process a plurality of adsorbent beds of the adsorbent material with a number "N" of substantially similar adsorbent beds, and said adsorbent beds having first and second ends;
- and the process including in each adsorbent bed the cyclically repeated steps at the cyclic frequency and in some sequence of:
- (A) introducing the gas mixture to the adsorbent bed,
- (B) generating cyclic pressure changes in the adsorbent bed, in a pressurization step increasing the working pressure of the adsorbent bed, and in a depressurization step decreasing the working pressure of the adsorbent bed, thus changing the working pressure of the adsorbent bed between the lower and higher pressures,
- (C) generating cyclically reversing flow of the gas mixture in the adsorbent bed, while establishing a relative phase between the reversing flow and the said pressure changes in the adsorbent bed,
- (D) generating gas flow in the adsorbent bed directed toward the first end of the adsorbent bed when the pressure is approximately the lower pressure, so that a first product gas enriched in the first component flows from the first end of the adsorbent bed at substantially the lower pressure,
- (E) generating gas flow in the adsorbent bed directed toward the second end of the adsorbent bed when the pressure is approximately the higher pressure, so that a second product gas enriched in the second component flows from the second end of the adsorbent bed at substantially the higher pressure,
- and the process is further characterized by:
- (F) recovering energy from a depressurization step of the adsorbent bed to assist performing the pressurization step of another of the adsorbent beds,
- (G) collecting as second product reflux gas a portion of the second product gas which has flowed from the second ends of the "N" adsorbent beds in above step (E) for each of the adsorbent beds, providing heat to the second product reflux gas at substantially the higher pressure, expanding the second product reflux from the higher to the lower pressure, and admitting the second product reflux gas to the second end of an adsorbent bed during step (D) for that adsorbent bed,
- (H) recovering mechanical energy from expanding the second product reflux gas in above step (G), and
- (I) maintaining the first end of the adsorbent bed at substantially a first temperature, and maintaining the second end of the adsorbent bed at substantially a second temperature.
Apparatus for separating first and second components of a 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, the apparatus including:
- (a) a plurality of "N" substantially similar adsorbent beds of the adsorbent material, each adsorbent bed having a first end and a second end,
- (b) means to generate cyclic pressure changes in each adsorbent bed at a cyclic frequency, in a pressurization step increasing the working pressure of the adsorbent bed, and in a depressurization step decreasing the working pressure of the adsorbent bed, so as to change the working pressure of the adsorbent bed between the lower and higher pressures,
- (c) means to generate a cyclically reversing flow of the gas mixture in each adsorbing bed at the cyclic frequency, cooperating with the means to generate cyclic pressure changes so as to establish a relative phase between the reversing flow and the pressure changes in each adsorbent bed,
- (d) means to generate gas flow in each adsorbent bed directed toward the first end of the adsorbent bed when the pressure is approximately the lower pressure, and means to generate gas flow in each adsorbent bed directed toward the second end of the adsorbent bed when the pressure is approximately the higher pressure,
- (e) feed supply means to introduce the gas mixture to each of the said adsorbent beds,
- (f) first product valve means to remove a first product gas enriched in the first component from the first end of each adsorbent bed, and second product valve means to deliver a second product gas enriched in the second component from the second end of each adsorbent bed,
- (g) first inlet valve means to admit gas to the first end of each adsorbent bed at substantially the higher pressure, and second inlet valve means to admit gas to the second end of each adsorbent bed at substantially the lower pressure,
- and the apparatus is further characterized by:
- (h) work energy exchange means to recover energy from a depressurization step of an adsorbent bed to assist performing the pressurization step of another of the adsorbent beds,
- (i) means to provide heat to a second product reflux gas at substantially the higher pressure, the second product reflux gas being a portion of the second product gas delivered from the second product valve means,
- (j) expander means to expand the second product reflux gas which has been heated by the heater means, from substantially the higher to the lower pressure,
- (k) compressor means cooperating with the first ends of the adsorbent beds, and cooperating with the work energy exchange means and the expander means to establish a pressure ratio between the higher and lower pressures,
- (l) means to recover mechanical power from the expander means to assist driving the compressor means, and
- (m) means to establish the first end of the bed at substantially a first temperature, and to establish the second end of the bed at substantially a second temperature.
Apparatus for separating first and second components of a 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 process cyclic frequency, the apparatus including:
- (a) a plurality of "N" substantially similar adsorbent beds of the adsorbent material, each adsorbent bed having a first end and a second end,
- (b) means to generate cyclic pressure changes in each adsorbent bed at a cyclic frequency, in a pressurization step increasing the working pressure of the adsorbent bed, and in a depressurization step decreasing the working pressure of the adsorbent bed, so as to change the working pressure of the adsorbent bed between the lower and higher pressures,
- (c) means to generate cyclically reversing flow of the gas mixture in each adsorbent bed at the cyclic frequency, cooperating with the means to generate cyclic pressure changes so as to establish a relative phase between the reversing flow and the pressure changes in each adsorbent bed,
- (d) means to generate gas flow in each adsorbent bed directed toward the first end of the adsorbent bed when the pressure is approximately the lower pressure, and means to generate gas flow in each adsorbent bed directed toward the second end of the adsorbent bed when the pressure is approximately the higher pressure,
- (e) feed supply means to introduce the gas mixture to each of the said adsorbent beds,
- (f) first product valve means to remove a first product gas enriched in the first component from the first end of each adsorbent bed, and second product valve means to deliver a second product gas enriched in the second component from the second end of each adsorbent bed,
- (g) first inlet valve means to admit gas to the first end of each adsorbent bed at substantially the higher pressure, and second inlet valve means to admit gas to the second end of each adsorbent bed at substantially the lower pressure,
- and the apparatus is further characterized by:
- (h) an intermediate pressure manifold with pressure modulation valve means to accept gas in turn from each adsorbent bed during a depressurization step of that adsorbent bed and to supply that gas to another adsorbent bed during a pressurization step of that adsorbent bed, thus exchanging gas between the adsorbent beds, and
- (i) pressure modulation pump means for the intermediate pressure manifold to cyclically vary the pressure of the intermediate pressure manifold within the intermediate pressure interval, so that the pressure in the intermediate pressure manifold is decreasing when the intermediate pressure manifold is accepting gas from an adsorbent bed during a depressurization step for that adsorbent bed, and the pressure in the intermediate pressure manifold is increasing when the intermediate pressure manifold is supplying gas to an adsorbent bed during a pressurization step for that adsorbent bed, so as to recover energy from a depressurization step of an adsorbent bed over an intermediate pressure interval between the higher and lower pressures to assist performing a pressurization step over an intermediate pressure interval for another of the adsorbent beds.
Apparatus for separating first and second components of a 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 process cyclic frequency, the apparatus including:
- (a) a plurality of "N" substantially similar adsorbent beds of the adsorbent material, each adsorbent bed having a first end and a second end,
- (b) means to generate cyclic pressure changes in each adsorbent bed at a cyclic frequency, in a pressurization step increasing the working pressure of the adsorbent bed, and in a depressurization step decreasing the working pressure of the adsorbent bed, so as to change the working pressure of the adsorbent bed between the lower and higher pressures,
- (c) means to generate cyclically reversing flow of the gas mixture in each adsorbent bed at the cyclic frequency, cooperating with the means to generate cyclic pressure changes so as to establish a relative phase between the reversing flow and the pressure changes in each adsorbent bed,
- (d) means to generate gas flow in each adsorbent bed directed toward the first end of the adsorbent bed when the pressure is approximately the lower pressure, and means to generate gas flow in each adsorbent bed directed toward the second end of the adsorbent bed when the pressure is approximately the higher pressure,
- (e) feed supply means to introduce the gas mixture to each of the said adsorbent beds,
- (f) means to remove a first product gas enriched in the first component from the first end of each adsorbent bed, and means to deliver a second product gas enriched in the second component from the second end of each adsorbent bed,
- (g) first inlet valve means to admit gas to the first end of each adsorbent bed at substantially the higher pressure, and second inlet valve means to admit gas to the second end of each adsorbent bed at substantially the lower pressure,
- and the apparatus further includes:
- (h) means to recover energy from a depressurization step of the adsorbent bed over an intermediate pressure interval between the higher and lower pressures to assist performing a pressurization step over substantially the same pressure interval of another of the adsorbent beds,
- (i) an intermediate pressure manifold with valve means to accept gas in turn from each adsorbent bed during a depressurization step of that adsorbent bed and to supply that gas to another adsorbent bed during a pressurization step of that adsorbent bed, thus exchanging gas between the adsorbent beds, and
- (j) flow modulation means to modulate the flow in the adsorbent bed during pressurization and depressurization steps.
Apparatus for separating first and second components of a 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 process cyclic frequency, the apparatus including:
- (a) a plurality of "N" substantially similar adsorbent beds of the adsorbent material, each adsorbent bed having a first end and a second end,
- (b) means to generate cyclic pressure changes in each adsorbent bed at a cyclic frequency, in a pressurization step increasing the working pressure of the adsorbent bed, and in a depressurization step decreasing the working pressure of the adsorbent bed, so as to change the working pressure of the adsorbent bed between the lower and higher pressures,
- (c) means to generate cyclically reversing flow of the gas mixture in each adsorbent bed at the cyclic frequency, cooperating with the means to generate cyclic pressure changes so as to establish a relative phase between the reversing flow and the pressure changes in each adsorbent bed,
- (d) means to generate gas flow in each adsorbent bed directed toward the first end of the adsorbent bed when the pressure is approximately the lower pressure, and means to generate gas flow in each adsorbent bed directed toward the second end of the adsorbent bed when the pressure is approximately the higher pressure,
- (e) feed supply means to introduce the gas mixture to each of the said adsorbent beds,
- (f) means to remove a first product gas enriched in the first component from the first end of each adsorbent bed, and means to deliver a second product gas enriched in the second component from the second end of each adsorbent bed,
- (g) first inlet valve means to admit gas to the first end of each adsorbent bed at substantially the higher pressure, and second inlet valve means to admit gas to the second end of each adsorbent bed at substantially the lower pressure,
- further characterized in that the means to generate gas flow in each adsorbent bed directed toward the first end of the adsorbent bed when the pressure is approximately the lower pressure, and the means to generate gas flow in each adsorbent bed directed toward the second end of the adsorbent bed when the pressure is approximately the higher pressure, include an expander and a compressor which are mechanically coupled as a compressor/expander combination.
Apparatus for generating energy by mixing of first and second gas components, 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, the apparatus including:
- (a) a plurality of "N" substantially similar adsorbent beds of the adsorbent material, each adsorbent bed having a first end and a second end,
- (b) means to generate cyclic pressure changes in each adsorbent bed at a cyclic frequency, in a pressurization step increasing the working pressure of the adsorbent bed, and in a depressurization step decreasing the working pressure of the adsorbent bed, so as to change the working pressure of the adsorbent bed between the lower and higher pressures,
- (c) means to generate cyclically reversing flow of the gas mixture in each adsorbent bed at the cyclic frequency, cooperating with the means to generate cyclic pressure changes so as to establish a relative phase between the reversing flow and the pressure changes in each adsorbent bed,
- (d) means to generate gas flow in each adsorbent bed directed toward the first end of the adsorbent bed when the pressure is approximately the lower pressure, and means to generate gas flow in each adsorbent bed directed toward the second end of the adsorbent bed when the pressure is approximately the higher pressure,
- (e) a second inlet valve means to admit a first feed stream containing the first component to adjacent the second end of the adsorbent beds at the lower pressure,
- (f) a first inlet valve means to admit a second feed stream containing the second component to adjacent the first end of the adsorbent beds at the higher pressure,
- (g) exhaust valve means deliver a gas mixture of the first and second components from adjacent the first end of the adsorbent beds at the lower pressure,
- (h) work energy exchange means to recover energy from a depressurization step of an adsorbent bed to assist performing the pressurization step of another of the adsorbent beds,
- (i) expander means to expand gas flowing from the second end of the adsorbent beds from substantially the higher to the lower pressure, and means to return that gas to the second ends of the adsorbent beds,
- (j) compressor means compressing the second feed stream to the higher pressure, and
- (k) means to recover mechanical power from the expander means to assist driving the compressor means, and to provide useful energy.
Dependencies are inferred from the claim text.