VIBRATION SIGNATURE BASED CONDITION MONITORING OF BOWL-ROLLER COAL PULVERIZERS

The overall objective of the work reported in this paper is to minimiz e the cost of power generation in thermal power stations utilizing pul verized coal combustion processes for steam generation. The strategy o f achieving this objective is based on an ''on-condition maintenance ' 'philosophy and vibration based diagnostic signature analysis techniqu es. The coal pulverizers reported on here are 783 RP (roll pressure) a nd 823 RP combustion engineering (CE) bowl-roller coal pulverizers (bo wl mills) installed at the State Energy Commission of Western Australi a (SECWA) power stations. This paper reviews the design philosophy, op erational principles, and system dynamics and establishes the procedur es for identifying the potential malfunction of bowl mills and their a ssociated components. The influence of operating parameters, such as c oal flow, primary air flow, and operating temperature, on mill vibrati on are investigated. The effects of journal spring force variation, su ch as magnitude, uneven spring force, and broken springs, are also stu died. Special attention is also given to the diagnosis of the top radi al bearing problem due to its remoteness from the bowl mill external s tructure. A spectral recovery technique utilizing the in verse frequen cy response function was developed for trend analysis and diagnostic p urposes.