Load following single bed reversing blower adsorption air separation system
An exemplary single bed reversing blower adsorption based air separation unit is configured to follow the O 2 load placed thereon by adjusting flow rates therethrough and power consumption. At least one and preferably multiple pressure sensors sense O 2 pressure within an O 2 storage region downstream of an adsorber vessel. These sensed pressures are utilized to generate control signals controlling flow rates at locations upstream of the compressor, such as at a reversible blower and an output compressor. Control loops for the blower and the compressor are independent of each other and have different time constants. Effective following of the O 2 load is thus achieved without driving the air separation unit into operational conditions outside of design and also maintaining optimal power consumption for the O 2 produced, such that efficiency is maintained over a large turndown ratio.
1. An air separation method with load sensing and load following, including the steps of:
sensing at least one pressure within a single adsorption bed air separation system having an air inlet upstream from a reversing blower and an O 2 storage downstream from the adsorption bed;
said sensing step detecting pressure magnitude at a first location downstream from the reversing blower;
altering a flow rate through the reversing blower responsive to the pressure of said sensing step;
wherein said sensing step includes the step of increasing a flow rate through the reversing blower when the pressure of said sensing step is below a set point and decreasing a flow rate through the reversing blower when the pressure of said sensing step is above the set point;
wherein a compressor is located within the O 2 storage downstream of the adsorption bed;
altering a flow rate through the compressor responsive to a second pressure at a second location, the second location downstream from the compressor; and
wherein said altering a flow rate through the reversing blower step and said altering a flow rate through the compressor step each occur multiple times separated by passage of at least two time intervals.
2. The method of claim 1 wherein a time interval for said altering a flow rate through the reversing blower step and a time interval for said altering a flow rate through the compressor step are different from each other.
3. The method of claim 2 wherein the time interval for control of the reversing blower is longer than the time interval for control of the compressor.
4. The method of claim 2 wherein the time interval for control of the reversing blower is approximately every minute and the time interval for control of the compressor is approximately every second.
5. The method of claim 2 wherein the time interval for control of the reversing blower is at least twice as long as the time interval for control of the compressor.
6. The method of claim 1 wherein said altering a flow rate through the reversing blower step and said altering a flow rate through the compressor step include the steps of driving the reversing blower and the compressor with separate variable frequency drives and controlling a rotational speed of the variable frequency drives responsive to the pressure at the first location and the pressure at the second location.
7. An air separation method with load sensing and load following, including the steps of:
sensing at least one pressure within a single adsorption bed air separation system having an air inlet upstream from a reversing blower and an O 2 storage downstream from the adsorption bed;
said sensing step detecting pressure magnitude at a first location downstream from the reversing blower;
altering a flow rate through the reversing blower responsive to the pressure of said sensing step;
increasing a flow rate through the reversing blower when pressure of said sensing step is below a set point;
decreasing a flow rate through the reversing blower when the pressure of said sensing step is above the set point;
wherein a compressor is located within the O 2 storage downstream of the adsorption bed;
further sensing a second pressure at a second location downstream from the first location and downstream from the compressor; and
altering a flow rate through the compressor responsive to the second pressure at the second location.
8. The load following air separation method of claim 7 wherein said altering a flow rate through the reversing blower step and said altering a flow rate through the compressor step each occur multiple times separated by passage of at least two time intervals.
9. The load following air separation method of claim 8 wherein time intervals for said altering a flow rate through the reversing blower step and for said altering a flow rate through the compressor step are different from each other.
10. The load following air separation method of claim 9 wherein the time interval for control of the reversing blower is longer than the time interval for control of the compressor.
11. The load following air separation method of claim 10 wherein the time interval for control of the reversing blower is approximately every minute and the time interval for control of the compressor is approximately every second.
12. The load following air separation method of claim 10 wherein the time interval for control of the reversing blower is at least twice as long as for control of the compressor.
13. The load following air separation method of claim 7 wherein said altering a flow rate through the reversing blower step and said altering a flow rate through the compressor step include the steps of driving the reversing blower and the compressor with separate variable frequency drives and controlling a rotational speed of the variable frequency drives responsive to the pressure at the first location and the pressure at the second location.
14. An air separation system with load sensing and load following, comprising in combination:
an air inlet upstream from a reversing blower and an O 2 storage downstream from an adsorption bed, said adsorption bed downstream from said reversing blower;
a pressure sensor downstream from said reversing blower sensing a first pressure magnitude at a first location downstream from said reversing blower;
a controller coupled to said first pressure sensor and altering a flow rate through the reversing blower responsive to the first pressure;
said controller having a set point, said controller increasing a flow rate through said reversing blower when the first pressure is below the set point, and decreasing a flow rate through said reversing blower when the first pressure is above the set point; and
a second pressure sensor at a second location downstream from said first pressure sensor, said second pressure sensor coupled to a controller of O 2 supply from said O 2 storage.
15. The system of claim 14 wherein a compressor is located downstream of said adsorption bed, said second pressure sensor located downstream from said compressor.
16. The system of claim 15 wherein said second pressure sensor is coupled to a controller that is coupled to said compressor to alter a flow rate through said compressor responsive to the second pressure sensed by said second pressure sensor.
17. The system of claim 16 wherein said controller of said reversing blower and said controller of said compressor each control flow rates, but at different time intervals, said reversing blower controller having a larger time interval than said compressor controller.
18. The system of claim 17 wherein the time interval for control of the reversing blower is approximately every minute and the time interval for control of the compressor is approximately every second.
19. The system of claim 17 wherein the time interval for control of said reversing blower is at least double the time interval for control of said compressor.
20. The system of claim 14 wherein said compressor is driven by a first variable frequency drive and said reversing blower is driven by a second variable frequency drive, each of said variable frequency drive is controlling a rotational speed of said variable frequency drives responsive to the pressure sensed by said first pressure sensor and the pressure sensed by said second pressure sensor.