PET reciprocating compressor
PET reciprocating compressor
(OP)
Hi everybody
Does anyone of You have some experiance with capacitity controll of reciprocating compressor by changing speed with frequancy converter?
Is it possible to controll from 1-100%?
Vibration problems?
Thank You for any suggestion!
Davor
Does anyone of You have some experiance with capacitity controll of reciprocating compressor by changing speed with frequancy converter?
Is it possible to controll from 1-100%?
Vibration problems?
Thank You for any suggestion!
Davor





RE: PET reciprocating compressor
To obtain more capacity, valve unloaders are typically used.
RE: PET reciprocating compressor
lmf.at has a PET package that is energy saving oriented 55-100% control.
dcasto, your suspicions on a seperate lube system is correct. I started up a recip with a DC motor that had variable speed capacity control. This type of design (VFD or DC) requires a comprehensive torsional analysis.
RE: PET reciprocating compressor
RE: PET reciprocating compressor
My aplication is 3 stage 40 bars reciprocating compressor driven by 200 kW electric motor with capacity control by load/unload.
When I use this compressor for blowing small format of bottels, motor run more than 70% unloaded.
So I intention is to install VSD for controling RPM of motor to have better compressor effitiancy.
I am electritian so I preffer electrical solution for my aplication if it is possible.
Can You give me some web source where I can find more information about my application
Thank You
RE: PET reciprocating compressor
RE: PET reciprocating compressor
you will need a torque effort curve of the compressor to size the VSD correctly.
I think you will find that the frame size of your new motor will need to be increased to have higher fan capacity for motor cooling, you may also may need to have additional air source for cooling the motor in low rpm's.
RE: PET reciprocating compressor
* Does your compressor never switch off - is it always either loaded or unloaded, but running? If true, this would seem to be one easy inefficiency to eliminate, limited by the number of starts permissible per hour possibly?
* Any change to the running speed will change the mechanical loadings on the compressor - the gas forces will remain similar but the inertial forces will change - can the design permit this? Not only bearings to consider here, I would suggest.
* A new motor, plus inverter drive is liable to be very expensive: plus, how much power is required by the inverter itself? How much saved money/increased efficiency is there likely to be in reality, and what will your payback be? You may find this is none/infinite - you may not.
* You are right to be concerned about vibrations at certain speed ranges. How are you going to find this out before purchasing and installing an expensive VFD system?
* The compressor cylinder valves will most likely be optimised to some degree or other for operation at the speed your compressor runs at currently. Will running at different speeds cause valve inefficiencies to outweigh any potential benefits of VFD?
* There are a multitude of possibilities for mechanical capacity control that would be a lot less capital intensive. Whether any of them would lead to any efficiency improvements for you (in the loosest sense) is a moot point, however.
* My opinion - do not do anything without a buy-in from the compressor manufacturer.
RE: PET reciprocating compressor
RE: PET reciprocating compressor
RE: PET reciprocating compressor
crjones is correct about lubrication. Depending on design, some components depend on slash lubrication.