Reversing blower adsorption utilizing coasting
A driving system for a reversing blower adsorption based air separation unit is configured to not only drive the reversing blower cyclically in a forward and in a reverse direction, but also to allow the reversing blower to coast during a portion of its operating cycle. While coasting, a pressure differential across the blower acts alone to switch the reversing blower between a forward and a reverse direction of operation. Less power is thus required. When coasting, the blower can also be configured to output power such as the drive motor functioning as an electric generator or by having a mechanical power input be driven by the blower for power generation and/or energy storage. Such a system beneficially utilizes the energy associated with the pressure differential across the blower for energy harvesting and to further accelerate cycle times for the reversing blower adsorption based air separation unit.
1. A method for operation of a reversing blower adsorption based air separation system, including the steps of:
operating a reversing blower inline with an adsorption bed and an O 2 output on a side of the adsorption bed opposite the reversing blower, to separate O 2 from air entering the reversing blower;
said operating step including a feed forward step with air driven through the reversing blower through the adsorption bed where N 2 is adsorbed and on to the O 2 output;
said operating step including a recovery reverse step with gas driven from the adsorption bed through the reversing blower by reverse operation of the reversing blower for removal of N 2 from an adsorption media in the adsorption bed;
said feed forward step and said recovery reverse step driven by gaseous flow through the reversing blower in opposite directions;
the reversing blower coupled to a drive motor which causes the blower to rotate in a forward drive direction and a reverse drive direction;
allowing the blower to coast between at least one period of forward drive and at least one period of reverse drive following the period of forward drive; and
wherein said allowing the blower to coast step includes allowing the blower to coast both as the blower slows down to a stop and continues coasting as the blower begins rotation in a direction opposite blower rotation before coming to a stop.
2. The method of claim 1 wherein said allowing step includes allowing the blower to coast between both the period of forward drive followed by the period of reverse drive and between a period of reverse drive followed by a period of forward drive.
3. The method of claim 1 wherein said recovery reverse step includes drawing a vacuum on the adsorption bed to remove nitrogen from the adsorption media within the adsorption bed.
4. The method of claim 1 including the further step of drawing power from the blower during at least a portion of said allowing step by placing a load on the blower coupled to an energy storage.
5. The method of claim 1 including the further step of controlling the drive motor to cause the drive motor to switch between driving the blower in a feedforward direction, driving the blower in a recovery reverse direction, and not driving the blower, responsive to control inputs from a controller.
6. A reversing blower adsorption air separation unit, comprising in combination:
an adsorption bed downstream from a reversing blower, and an oxygen output downstream from said adsorption bed;
the reversing blower coupled to a drive motor which drives the blower in both a forward rotating and a reverse rotating direction, said forward rotating direction driving air through said reversing blower and then through said adsorption bed, and said reverse rotating direction driving gas from said adsorption bed and then through said reversing blower;
a controller coupled to the motor, the controller switching the motor between a forward drive mode, a reverse drive mode and an off mode with said motor not driving said blower either forward or reverse; and
wherein a mechanical power input is selectively coupleable to the blower to put a load on the blower and draw mechanical power from the blower to an energy storage.
7. The system of claim 6 wherein said motor is coupled to a battery and operates as a generator driven by said blower to store electric energy within said battery during at least a portion of a period that said motor is in said off mode with said motor not driving said blower.