PSA Separation of Nitrogen from Natural Gas

A pressure swing adsorption (PSA) process for generating methane-enriched product gas from nitrogen-contaminated natural gas, which comprises the steps of:

• Step 1:
• Feed=“FD”=feeding an adsorber A with pressurized nitrogen-contaminated natural gas, while the gas that is enriched in the less-strongly adsorbed components flows from adsorber A and is collected in a first receiver vessel as a first product gas;
• Step 2:
• Pressure Equalization 1 (Effluent)=“PE1(E)”=simultaneous to commencement of the Feed step (FD) in adsorber A, allowing the pressurized gas in an adsorber B (enriched in the less-strongly adsorbed components) to depressurize co-currently into an adsorber E, reducing the pressure in said adsorber B by allowing it to equalize with that in adsorber E;
• Step 3:
• Pressure Equalization 2 (Effluent)=“PE2(E)”=while the Feed step (FD) is proceeding in adsorber A, immediately after the “PE1(E)” is complete in adsorber B, allowing the pressurized gas still in said adsorber B (which is also enriched in the less-strongly adsorbed components) to depressurize co-currently into adsorber D, further reducing the pressure in adsorber B by allowing it to equalize with that in said adsorber D;
• Step 4:
• Hold 1=“H1”=a null step for adsorber B, as there is no flow into or out of adsorber B. This step commences upon the conclusion of Step 3.
• Step 5:
• Pressure Equalization 3 (Effluent)=“PE3(E)”=while the Feed step (FD) is proceeding in adsorber A, after the “H1” step is complete in adsorber B, allowing the pressurized gas still in adsorber B (which is also enriched in the less-strongly adsorbed components) to depressurize co-currently into an adsorber C, further reducing the pressure in adsorber B by allowing it to equalize with that in adsorber C;
• Step 6:
• Blowdown=“BD”=simultaneous to commencement of the Feed step (FD) in adsorber A, counter-currently releasing from adsorber C some of the gas that is enriched in the more-strongly adsorbed components yielding a second product gas, which flows into the second receiver vessel for its collection, the pressure in this step varying from the final pressure attained in “PE3(E)” to about atmospheric pressure;
• Step 7:
• Evacuation=“EV”=while the Feed step (FD) is proceeding in adsorber A, counter-currently releasing from adsorber C some of the remaining gas that is enriched in the more-strongly adsorbed components yielding a third product gas, which is withdrawn from adsorber C via a vacuum pump and from there into the second receiver vessel for its collection, the pressure in this step varying from the final pressure attained in “BD” to about the limiting lowest pressure;
• Step 8:
• Purge=“PU”=purging adsorber C with a portion of the first product gas, comprising less-strongly adsorbed components;
• Step 9:
• Pressure Equalization 3 (Influent)=“PE3(I)”=while the Feed step (FD) is proceeding in adsorber A, and simultaneous with the counterpart Pressure Equalization (Effluent) “PE3(E)” step, occurring in adsorber B, allowing the pressurized gas still from adsorber B (which is enriched in the less-strongly adsorbed components) to repressurize counter-currently adsorber C, increasing the pressure in adsorber C by allowing it to equalize with that in adsorber B;
• Step 10:
• Hold 2=“H2”=simultaneous to commencement of the Feed step (FD) in adsorber A, a null step begins in adsorber D, as there is no flow into or out of adsorber D;
• Step 11:
• Pressure Equalization 2 (Influent)=“PE2(I)”=while the Feed step (FD) is proceeding in adsorber A, at the conclusion of the Hold 2 (“H2”) step in adsorber D, and simultaneous with the counterpart Pressure Equalization (Effluent) “PE2(E)” step occurring in adsorber B, allowing the pressurized gas still from adsorber B (which is enriched in the less-strongly adsorbed components) to repressurize counter-currently adsorber D, increasing the pressure in adsorber D by allowing it to equalize with that in adsorber B;
• Step 12:
• Hold 3=“H3”=simultaneous to conclusion of the Pressure Equalization 2 (Influent)=“PE2(I)” step in adsorber D, a null step begins in adsorber D, as there is no flow into or out of adsorber D;
• Step 13:
• Pressure Equalization 1 (Influent)=“PE1(I)”=simultaneous to commencement of the Feed step (FD) in adsorber A, and simultaneous with the counterpart Pressure Equalization (Effluent) “PE1(E)” step occurring in adsorber B, allowing the pressurized gas still from adsorber B (which is enriched in the less-strongly adsorbed components) to repressurize counter-currently in an adsorber E, increasing the pressure in adsorber E by allowing it to equalize with that in adsorber B;
• Step 14:
• Hold 4=“H4”=simultaneous to conclusion of the Pressure Equalization 1 (Influent)=“PE1(I)” step in adsorber E, a null step begins in adsorber E, as there is no flow into or out of adsorber E;
• and
• Step 15:
• Repressurize with Product=“RP”=pressurizing adsorber E by admitting a portion of the first product gas, which is enriched in the less-strongly adsorbed components. wherein adsorbers A, B, and C each are at least partially filled with solid adsorbent.

A pressure swing adsorption (PSA) process for generating methane-enriched product gas from nitrogen-contaminated natural gas, which comprises the steps of:

• Step 1:
• Feed=“FD”=feeding an adsorber A with Feed gas comprising pressurized nitrogen-contaminated natural gas, while the gas that is enriched in the less-strongly adsorbed components flows from adsorber A and is collected in a first receiver vessel as a first product gas;
• Step 2:
• Pressure Equalization 1 (Effluent)=“PE1(E)”=simultaneous to commencement of the Feed step (FD) in adsorber A, allowing the pressurized gas in an adsorber B (enriched in the less-strongly adsorbed components) to depressurize co-currently into an adsorber E, reducing the pressure in adsorber B by allowing it to equalize with that in adsorber E;
• Step 3:
• Pressure Equalization 2 (Effluent)=“PE2(E)”=while the Feed step (FD) is proceeding in adsorber A, immediately after the “PE1(E)” is complete in adsorber B, allowing the pressurized gas still in adsorber B (which is also enriched in the less-strongly adsorbed components) to depressurize co-currently into an adsorber D, further reducing the pressure in adsorber B by allowing it to equalize with that in adsorber D;
• Step 4:
• Pressure Equalization 3 (Effluent)=“PE3(E)”=while the Feed step (FD) is proceeding in adsorber A, after the “PE2(E)” is complete in adsorber B, allowing the pressurized gas still in adsorber B (which is also enriched in the less-strongly adsorbed components) to depressurize co-currently into an adsorber C, further reducing the pressure in adsorber B by allowing it to equalize with that in adsorber C;
• Step 5:
• Blowdown=“BD”=simultaneous to commencement of the Feed step (FD) in adsorber A, counter-currently releasing from adsorber C some of the gas that is enriched in the more-strongly adsorbed components yielding a second product gas, which flows into the second receiver vessel for its collection, the pressure in this step varying from the final pressure attained in “PE3(E)” to about atmospheric pressure;
• Step 6:
• Evacuation=“EV”=while the Feed step (FD) is proceeding in adsorber A, counter-currently releasing from adsorber C some of the remaining gas that is enriched in the more-strongly adsorbed components yielding a third product gas, which is withdrawn from adsorber C via a vacuum pump and from there into the second receiver vessel for its collection, the pressure in this step varying from the final pressure attained in “BD” to about the limiting lowest pressure;
• Step 7:
• Purge=“PU”=purging adsorber C with a portion of the first product gas, consisting of less-strongly adsorbed components;
• Step 8:
• Pressure Equalization 3 (Influent)=“PE3(I)”=while the Feed step (FD) is proceeding in adsorber A, and simultaneous with the counterpart Pressure Equalization (Effluent) “PE3(E)” step, occurring in adsorber B, allowing the pressurized gas still from adsorber B (which is enriched in the less-strongly adsorbed components) to repressurize counter-currently adsorber C, increasing the pressure in adsorber C by allowing it to equalize with that in adsorber B;
• Step 9:
• Hold 1=“H1”=simultaneous to commencement of the Feed step (FD) in adsorber A, a null step begins in adsorber D, as there is no flow into or out of adsorber D;
• Step 10:
• Pressure Equalization 2 (Influent)=“PE2(I)”=while the Feed step (FD) is proceeding in adsorber A, at the conclusion of the Hold 1 (“H1”) step in adsorber D, and simultaneous with the counterpart Pressure Equalization (Effluent) “PE2(E)” step occurring in adsorber B, allowing the pressurized gas still from adsorber B (which is enriched in the less-strongly adsorbed components) to repressurize counter-currently adsorber D, increasing the pressure in adsorber D by allowing it to equalize with that in adsorber B;
• Step 11:
• Hold 2=“H2”=simultaneous to conclusion of the Pressure Equalization 2 (Influent)=“PE2(I)” step in adsorber D, a null step begins in adsorber D, as there is no flow into or out of adsorber D;
• Step 12:
• Pressure Equalization 1 (Influent)=“PE1(I)”=simultaneous to commencement of the Feed step (FD) in adsorber A, and simultaneous with the counterpart Pressure Equalization (Effluent) “PE1(E)” step occurring in adsorber B, allowing the pressurized gas from adsorber B (which is enriched in the less-strongly adsorbed components) to repressurize counter-currently adsorber E, increasing the pressure in adsorber E by allowing it to equalize with that in adsorber B;
• Step 13:
• Hold 3=“H3”=simultaneous to conclusion of the Pressure Equalization 1 (Influent)=“PE1(I)” step in adsorber E, a null step begins in adsorber E, as there is no flow into or out of adsorber E;
• and
• Step 14:
• Repressurize (with Product)=“RP”=pressurizing adsorber E by admitting a portion of the first product gas, which is enriched in the less-strongly adsorbed components.

A parallelly-connected five adsorber, pressure swing adsorption (PSA) process for separating a gas mixture into a first gas product enriched in a first less strongly adsorbed gas component, and a second gas product enriched in a second more strongly adsorbed gas component, wherein each of said adsorbers is at least partially filled with solid adsorbent, which comprises the steps of:

• synchronizing the steps, such that the five parallel adsorbers, A, B, C, D, and E, operate the same and in a coordinated fashion, such that each of the five parallel adsorbers is out-of-phase from the other adsorbers by 2π/5, characterized in that:
• Adsorber A undergoes Feed (“FD”), with simultaneous production of the first product gas in the same elapsed time as:
• Adsorber B sequentially undergoes Pressure Equalization 1 (Effluent)=“PE1(E)”+Pressure Equalization 2 (Effluent)=“PE2(E)”+Pressure Equalization 3 (Effluent)=“PE3(E)” while
• Adsorber C sequentially undergoes Blowdown=“BD”+Evacuation=“EV”+Purge=“PU”+Pressure Equalization 3 (Influent)=“PE3(I)” while
• Adsorber D sequentially undergoes Pressure Equalization 2 (Influent)=“PE2(I)” while
• Adsorber E sequentially undergoes Pressure Equalization 1 (Influent)=“PE1(I)”+Repressurize with Product=“RP”;
• wherein synchronization of the steps requires that:
• Pressure Equalization 1 (Influent)=“PE1(I)” coincides with Pressure Equalization 1 (Effluent)=“PE1(E)”;
• Pressure Equalization 2 (Influent)=“PE2(I)” coincides with Pressure Equalization 2 (Effluent)=“PE2(E)”;
• and
• Pressure Equalization 3 (Influent)=“PE3(I)” coincides with Pressure Equalization 3 (Effluent)=“PE3(E)”;
• provided that the elapsed time of the Feed Step in adsorber A coincides with the sequence of steps:
• Blowdown=“BD”+Evacuation=“EV”+Purge=“PU”+Pressure Equalization 3 (Influent)=“PE3(I)” in adsorber C;
• provided further that adsorbers B, D, and E are not so limited when Hold Steps are inserted between one or more of adsorbers B, D, and E.