Page 368 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Steam Turbines and Turboexpanders 347

8. From 3,500 rpm, raise the speed by increments of 1 ,OOO rpm up to
running speed going rapidly through the criticals.
If running smoothly, and a sudden severe jump in vibration occurs,
immediately drop the speed to 2,000 rpm or less for about 112 hour.
The carbon ring seals were grabbing the shaft. After a 1/2 hour cool
down, return the turbine to operating speed.
9. Run at normal maximum running speed for one hour prior to check-
ing the overspeed trip and coupling up.
This procedure has produced consistently positive results with a
variety of machines, some of which were considered to be charac-
teristically bad performers. The key to a successful and long life
carbon ring break-in is patience and the continuous presence of an
operator through the entire procedure to handle any contingency.

Operation of Large Steam lhrbfnes

Finally, if we adhere to the interface concept of large steam turbine
maintenance and operation we must not forget to establish proper operat-
ing procedures. Here again, each plant will more often than not base
its procedures on the manufacturer’s general operating instructions. Typ-
ically these written procedures contain:

General description of the turbine train.
Emergency equipment and procedures.
Initial startup.
Normal startup.
Emergency shutdown.
Major components, care and feeding.

The following are a manufacturer’s instructions for the operation of a
special purpose condensing turbine. *

General. This procedure is recommended for starting and putting the tur-
bine in operation. It is obvious that any such instructions can cover only
the normal case and it will be recognized that under unusual circum-
stances, variations from this program will have to be adopted and the
procedure to be followed will necessarily be determined by the bzst judg-
ment of the operating engineers.
Before starting the turbine, clean off any dirt which may have accumu-
lated during the installation or turnaround work and be sure that dirt has

* Courtesy Wsthghouse Canada Ltd., Hamilton, Ontario, Canada.