Press Start Up

January 19, 2011

When customers request a suggestions for starting up a new screw press, we refer them to the Owners Manual. The key elements are as follows:

Check that there is compressed air for the discharge cone and that there is oil in the gearbox.

Find out where the manual disconnect, stop button, or breaker is located. If there is an emergency of any sort it is important to know where to shut off the press.

Give quick safety instructions: keep hands out of the inlet hopper, and keep hands away from where they might get pinched by the cone. The rest is obvious and normal.

Bump the press to make sure the direction of rotation is correct and that there is no severe rubbing. The direction of rotation is this: if you are sitting on the gearbox looking towards the discharge cone, the screw should be turning counter-clockwise.

Make sure the press liquor drain is hooked up and that there is a way for the press cake to be removed from the area of the press.

Make sure that the lubrication equipment is in place. The most critical item is having lubrication for the cone bushing(s).

Make sure the cone runs in and out. If it is jerky without the press in operation, get the screw turning and make sure that the in-out motion smoothes out.

When ready to get going, set the cone air pressure very low, say one bar. Turn on the press. If practical, start feeding material into the press with the cone in the open (withdrawn) position. Assuming it does not jam and no funny noises or vibration are evident, ease the cone shut once some material is seen coming out of the cake discharge.

Monitor the motor amps while doing this. If the amps spike, the press is jamming. When this happens, stop feeding material into the press and leave the press running with the cone open. If the jamming is bad enough to trip out the motor, run the press in reverse to try and loosen the jammed material. Then switch back to forward in an effort to clear the press.

Assuming that there are no problems, expect the cone (shortly after it is shut) to gradually come open. Some cake should start coming out. At that point, increase the air pressure on the cone. Monitor the motor amps while doing this, backing off the feed or air pressure if the motor seems to be overloading.

Likely it is best to start out at full line frequency, either 60 or 50 Hertz. Once relatively stable operation is achieved, try changing the drive frequency. Generally think of lowering the Hertz in order to get dryer cake.

Check the level in the inlet hopper. Set the feed to the press to be such that the incoming material barely or partly covers the screw in the inlet hopper.

Look out for vibration or shuddering in the press. That would indicate that it may be getting close to jamming or tripping out.

Issue 229