Instrument air system and method

1. An instrument air system relating to the reduction of hydrocarbon emissions of a process using a pneumatic process-control subsystem, the instrument air system comprising:

a shaft-driven air compressor configured to generate instrument air by compressing atmospheric air;

a power take off configured to derive drive torque from a driven rotary shaft of the process, the power take off including a concentrically-mounted clamping collar adapted to frictionally engage the driven rotary shaft;

a torque-transfer assembly configured to transfer the drive torque derived by the power take off to the shaft-driven air compressor, the torque-transfer assembly comprising a set of interoperating gears including a ring gear operably coupled to the clamping collar; and

an instrument-air pathway configured to supply the instrument air generated by the shaft-driven air compressor to the pneumatic process-control subsystem.

2. The instrument air system of claim 1 , wherein the instrument-air pathway further comprises an air storage tank configured to store the instrument air generated by the shaft-driven air compressor.

3. The instrument air system of claim 1 , wherein the instrument-air pathway further comprises an instrument-air dryer configured to remove moisture from the instrument air generated by the shaft-driven air compressor.

4. The instrument air system of claim 1 , wherein the interoperating gears of the torque-transfer assembly are adapted to convert an output shaft speed of the driven rotary shaft to an input shaft speed required to operate the shaft-driven air compressor.

5. The instrument air system of claim 1 , further comprising:

a support housing configured to supportively house the power take off and the torque-transfer assembly;

wherein the support housing comprises a rotary-shaft passage adapted to pass the driven rotary shaft through the support housing.

6. The instrument air system of claim 5 , wherein

the support housing comprises an internal gear chamber configured to contain the set of interoperating gears of the torque-transfer assembly; and

the internal gear chamber contains a volume of lubrication fluid adapted to lubricate the interoperating gears during operation.

7. The instrument air system of claim 5 , further comprising a support bracket configured to support the shaft-driven air compressor from the support housing.

8. The instrument air system of claim 5 , further comprising at least one motion restraint to restrain motion of the support housing induced by torque coupling with the driven rotary shaft.

9. The instrument air system of claim 5 , further comprising

at least one shaft bearing adapted to concentrically engage the driven rotary shaft;

wherein the at least one shaft bearing is mounted to the support housing; and

wherein the at least one shaft bearing is configured provide reduced-friction positioning of the support housing relative to the driven rotary shaft.

10. The instrument air system of claim 9 , wherein

the shaft bearing comprises a split bearing assembly having multiple bearing sections adapted to engage the driven rotary shaft while the driven rotary shaft is operably coupled to the process; and

the support housing comprises a first housing section and a second housing section; and

the first housing section and the second housing section define a first line of separation arranged to enable mounting of the support housing around the driven rotary shaft while the driven rotary shaft is operably coupled to the process.

11. The instrument air system of claim 10 , wherein the first housing section comprises a first mating surface extending along the first line of separation; the second housing section comprises a second mating surface extending along the first line of separation; the support housing further comprises a first seal provided between the first mating surface and the second mating surface, the first seal adapted to form a fluid-tight barrier along the first line of separation when the first housing section is joined with the second housing section; and the first mating surface and the second mating surface define a separation plane intersecting the rotary-shaft passage.

12. The instrument air system of claim 11 , wherein:

the first housing section and the second housing section each comprise at least two subsections adapted to divide the first housing section and the second housing section along a second line of separation; and

the support housing further comprises a second seal adapted to form a fluid-tight barrier along the second line of separation when the at least two subsections are joined.

13. The instrument air system of claim 1 , wherein the set of interoperating gears comprise toothed gears.

14. The instrument air system of claim 1 , wherein the instrument-air pathway further comprises at least one pneumatic coupler configured to operably couple the instrument air generated shaft-driven air compressor to the pneumatic process-control subsystem.

15. The instrument air system of claim 1 , further comprising at least one instrument-air pneumatic process-control device adapted to replace at least one existing gas pneumatic process-control device of the pneumatic process-control subsystem.

16. The instrument air system of claim 1 , wherein

the process comprises a petroleum-gas compressor; and

the power take off is configured to engage the driven rotary shaft driving a cooling fan of the petroleum-gas compressor.

17. An instrument air system relating to the reduction of hydrocarbon emissions of a process using a pneumatic process-control subsystem, the instrument air system comprising:

a shaft-driven air compressor configured to generate instrument air by compressing atmospheric air;

a power take off configured to derive drive torque from a driven rotary shaft of the process, the power take off including a concentrically-mounted clamping collar adapted to frictionally engage the driven rotary shaft;

a torque-transfer assembly configured to transfer the drive torque derived by the power take off to the shaft-driven air compressor, the torque-transfer assembly comprising a set of interoperating gears including a ring gear mounted to the clamping collar;

a support housing configured to supportively house the power take off and the torque-transfer assembly;

a support bracket configured to support the shaft-driven air compressor from the support housing;

at least one motion restraint to restrain motion of the support housing induced by torque coupling with the driven rotary shaft;

at least one shaft bearing adapted to concentrically engage the driven rotary shaft;

an air storage tank configured to store a volume of the instrument air generated by the shaft-driven air compressor;

an instrument-air dryer configured to remove moisture from the instrument air generated by the shaft-driven air compressor; and

an instrument-air pathway configured to supply the instrument air generated shaft-driven air compressor to the pneumatic process-control subsystem;

wherein

the support housing comprises an internal gear chamber configured to contain the set of interoperating gears of the torque-transfer assembly;

the set of interoperating gears comprise toothed gears;

the toothed gears are adapted to convert an output shaft speed of the driven rotary shaft to an input shaft speed required to operate the shaft-driven air compressor;

the support housing comprises a rotary-shaft passage adapted to pass the driven rotary shaft through the support housing;

the internal gear chamber contains a volume of lubrication fluid adapted to lubricate the interoperating gears during operation;

the at least one shaft bearing is mounted to the support housing at the rotary-shaft passage;

the at least one shaft bearing is configured provide reduced-friction positioning of the support housing relative to the driven rotary shaft;

the shaft bearing comprises a split bearing assembly having multiple bearing sections engagable on the driven rotary shaft while the driven rotary shaft is operably coupled to the process;

the support housing comprises a first housing section and a second housing section;

a first line of separation between the first housing section and the second housing section is arranged to enable mounting of the support housing around the driven rotary shaft while the driven rotary shaft is operably coupled to the process; and

the power take off is configured to engage the driven rotary shaft driving a cooling fan of a petroleum-gas compressor.

18. The instrument air system of claim 17 , further comprising

a set of instructions; and

wherein the instrument air system is arranged as a kit.