Hi All,
With reference to a gas turbine driven compressor train designed to API, for some reason a turbine has been choosen with much higher available power than max required by compressors. Typically 25 MW are available at gas turbine output power at site conditions while the compressors require only around 15 MW max. There is a gearbox between Gas turbine and compressors. Apart from the Gas turbine issues in running on low load, my question concerns the design of train elements.
Normally the sizing of the couplings and gearbox obey to API671 and 613 last editions respectively. That is to say Gas turbine rated power should be considered for the sizing of the couplings and gearbox with the applicable Service factors as given by the above mentionned codes.
In an attempt to reduce the size the couplings and gearbox, the first thing that has been done was to investigate the max compressor absorbed power in the worse process scenario that could hypothetically envizaged. The second thing was to opt for power limitation of the Gas Turbine (by mean of software control) and then squeeze the size of the couplings and the gearbox.
Here are my concerns:
- Is it a sound engineering practice to design the train elements according to the max. compression power (of course considering to include some service factor) ? What if there is a process upset that was not expected ? How this would pass third party certification step ?
- In the option of Gas turbine power limitation by mean of control devices (software based), is this practice safe and in line with API requirements ?
Thanks if you can share your experience
Regards
With reference to a gas turbine driven compressor train designed to API, for some reason a turbine has been choosen with much higher available power than max required by compressors. Typically 25 MW are available at gas turbine output power at site conditions while the compressors require only around 15 MW max. There is a gearbox between Gas turbine and compressors. Apart from the Gas turbine issues in running on low load, my question concerns the design of train elements.
Normally the sizing of the couplings and gearbox obey to API671 and 613 last editions respectively. That is to say Gas turbine rated power should be considered for the sizing of the couplings and gearbox with the applicable Service factors as given by the above mentionned codes.
In an attempt to reduce the size the couplings and gearbox, the first thing that has been done was to investigate the max compressor absorbed power in the worse process scenario that could hypothetically envizaged. The second thing was to opt for power limitation of the Gas Turbine (by mean of software control) and then squeeze the size of the couplings and the gearbox.
Here are my concerns:
- Is it a sound engineering practice to design the train elements according to the max. compression power (of course considering to include some service factor) ? What if there is a process upset that was not expected ? How this would pass third party certification step ?
- In the option of Gas turbine power limitation by mean of control devices (software based), is this practice safe and in line with API requirements ?
Thanks if you can share your experience
Regards
