Challenges in Screw Design

Challenges in Twin Screws Design

Why performance Twin Screw Compressor will drop over a period of time. and by overhauling will not improve it's performance (efficiency)? 

Note: 

The clearances; 

Between the male and female rotors. 

The clearances; 

Between the rotors and the Housing (Compressor case). 

The Clearances are seal by using it's compressor oil (coolant), therefore, it is very IMPORTANT to use the right quality of coolant. 

At this moment in time, We in Malaysia, have many challenges to repair the sealing strips, and to make the clearances between the screws, as well as screw and the housing (Compressor Case) clearance back to original position. 

Why we need to overhaul? 

Here are some reasons. 

"Blow Hole" 

Back pressure leakage that happens to ALL SCREW Compressors called the " BLOW HOLE" 

We name it as Blowhole; the compressed air leakage back to the inlet (Suction), from high pressure side at far end. 

Due to the pressure difference between the two extreme end. 

The "Blow Hole" will get Bigger over time, cause by the wear and tear of the bearings. As such, Overhaul and replacement of Air-End bearings are unavoidable. 

RESULTS from "Blow Hole": 

* Air-End will get hotter and the compressor trip 

* Free Air Delivery will be lesser & lesser 

* Oil & Air leaking all over 

The Higher discharge pressure will cause a thrust force between screw rotors and end plate, and is transmitted or pick up by the bearings.

Thermal Expansion:

Due to huge temperature difference between inlet side and discharge side.

In this case:

Inlet temperature = 70 degree F,

Discharge temperature = 200 degree F