6 replies to this topic

[farid.k]

Is there any guide for the choose of the compressor driver?
Operation request tu use steam turbine driven as it is more stable compared to motor driven. I prefer to use motor as easier and no need steam supply. They said, steam turbine more stable means rarely trip compared to motor driven. For me, if the trip is the issue, adjusting the related transmitter or sensor setting point will eliminate the trip problem am i right?
Seeking your opinion..

[Zauberberg]

Perhaps the local power supply reliability is fairly low - this could cause frequent trips of an electric motor (e.g. due to voltage dip or complete power loss). Check with Ops what do they exactly refer to when saying "less stable" operation of electric motor.

 

Driver selection is an optimized decision between the life cycle cost and the required availability of the machine. If there is excess steam on site, or if power availability is low, one would normally think of employing steam turbine as driver. Electric motors require less maintenance, they have higher reliability (excluding availability of external power supply), and depending on size they could be an option with less Capex. But again, site conditions need to be factored in when choosing the driver - and we don't know anything about those.

[farid.k]

Perhaps the local power supply reliability is fairly low - this could cause frequent trips of an electric motor (e.g. due to voltage dip or complete power loss). Check with Ops what do they exactly refer to when saying "less stable" operation of electric motor.

 

Driver selection is an optimized decision between the life cycle cost and the required availability of the machine. If there is excess steam on site, or if power availability is low, one would normally think of employing steam turbine as driver. Electric motors require less maintenance, they have higher reliability (excluding availability of external power supply), and depending on size they could be an option with less Capex. But again, site conditions need to be factored in when choosing the driver - and we don't know anything about those.

thanks zauberberg for detail explainantion.

i try to dig the answer for the cause of the motor trip and will let you know

[farid.k]

 

Perhaps the local power supply reliability is fairly low - this could cause frequent trips of an electric motor (e.g. due to voltage dip or complete power loss). Check with Ops what do they exactly refer to when saying "less stable" operation of electric motor.

 

Driver selection is an optimized decision between the life cycle cost and the required availability of the machine. If there is excess steam on site, or if power availability is low, one would normally think of employing steam turbine as driver. Electric motors require less maintenance, they have higher reliability (excluding availability of external power supply), and depending on size they could be an option with less Capex. But again, site conditions need to be factored in when choosing the driver - and we don't know anything about those.

thanks zauberberg for detail explainantion.

i try to dig the answer for the cause of the motor trip and will let you know

 

Dear Zauberberg

 

I did asked operation regarding to the cause of the motor trip. They said that, motor always trip due to the surging. That’s why they want to go for the steam turbine.

 

But for me, no matter the driver, surging will happened isn’t? Seems like the reason that they give is not valid isn’t?

[Zauberberg]

It may or it may not happen - it depends on the controls and available compressor protection systems. I don't know what causes the existing compressors to move into surge conditions. Maybe the steam-driven compressor operates always and the motor-driven compressor(s) kick in at a preset condition (e.g. IA header pressure drops to certain value), and they keep pumping air into the network till they enter into surge conditions, without any mechanism to protect them from surging (except shutdown). This is one scenario I could imagine. It all depends on how the machines and the controls are configured - this is all I can say at the moment.

 

Basically you are correct by saying that there is no difference between motor and steam turbine driver with regards to exposure of the compressor to surge conditions - with all things being equal between the two examples. Without proper controls, both of them can enter into surging.

 

I would also look for support from recognized experts in compressed air systems such as Atlas Copco, once I have collected and verified all the details of the problem. Consulting the manufacturers of the existing machines and discuss compressor controls and other issues should also be on your task list. Discussing the problem with Instrument & Controls engineer as well.

[Virginia]

 Hello Farid, 

 

The type of driver selection depends upon the Compressor inlet flow and compressor speed. For higher flows steam turbine is preferred. 

 

Regards

[farid.k]

 Hello Farid, 

 

The type of driver selection depends upon the Compressor inlet flow and compressor speed. For higher flows steam turbine is preferred. 

 

Regards

any figure number for what flowrate suit to steam turbine, and what flowrate suit to motor?

based on my reading, it will be based on plant capability and reliability.