Discussion on changing technology of large slewing bearing of bucket turbine

Bucket turbine is the main equipment of the coal conveying system, and the  operation status of bucket turbine directly affects the load of the  unit.Large slewing bearing is an important part of bucket turbine rotary  mechanism. After the slewing bearing is damaged, how to replace it safely  and with high quality in a short time is the main purpose of this paper.  This paper analyses the cause of damage of large slewing bearing and  introduces emphatically the technology of "jacking method" to replace large  slewing bearing of bucket turbine. This method is used to replace the big  bearing of DQL1200/1600-30 type bucket turbine of shentou NO.2 power plant.  The practice proves that this method is successful. The construction period  is only 6 days and the cost is 100,000 yuan. More than 1 year of operation  after replacement, stable rotation, good meshing of big and small gears,  normal operation and rated output.

The reasons for turbine large slewing bearing damage are as follows:
(1) Big bearing has been in service for 12 years, with a long cycle.  Defects were exposed as early as 2001 when it was overhauled.



(2) The track foundation of the bucket turbine used to be a reservoir,  which was a soft foundation. The uneven subsidence occurred during years of  operation. The bearing was in an inclined state when working, and it was  subjected to additional forces and accelerated wear.

(3) Aging of bearing vulcanized rubber seal and dust entering into the  inner part of the bearing;

(4) Overload when taking coal.

When the direction of the reclaimer's bracket to walking track is 90  degrees, upper slewing platform and the lower fixed platform of jack-up  exactly in the same vertical line, but consider the is the first time to  replace the large bearing, in order to ensure safety, and big bearing  horizontal access to leave enough space for the future, the same thickness  of steel plate, the lower part of the original jack-up 0.4 m respectively  extends outward. In this way, the extension part does not need to be  removed after the gun repair, so that the bearing can be checked later  using the jack lift replacement process.

Keep the cantilever perpendicular to the track, lift the cantilever, and  move the cantilever to the preset position. At this time, the cantilever  front of the bucket falls on the preset coal pile (proper sleeper is placed  between the coal pile and the cantilever), making the cantilever be built  up by the coal pile. At this point, the counterweight wire rope relaxes but  cannot leave the pulley groove. Special note: the tightness of the steel  wire rope shall ensure that when the upper rotary platform is jacked up to  180 mm, the steel wire rope is still slightly slack, and the weight of the  cantilever head still falls on the coal pile to maintain the balance and  stability of the rotary platform.