Maintenance and Inspection - Blower
September 8, 2003

Introduction Maintenance and Inspection Schedule Impeller Washing Lubrication System Shutdowns Electric Motor Problems

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Introduction

The manufacturer’s maintenance procedures and recommendations should be reviewed and strictly adhered to in order to ensure the proper operation of the equipment.   The following is provided as a general guideline only.

Maintenance and Inspection Schedule

Shift	Check and record vibration and temperature readings.
Daily	Check oil level in reservoir. Check pressure drop across the oil filter.  Switch to spare filter and replace dirty filter.
Weekly	Check condition of oil.  Ensure that there is no water in the oil.
Monthly	Measure and record machine noise levels Check oil filter and clean or replace as required. Check gear box oil seals for leaks. Clean gear box vent filter.
Shutdown	Every year, the following should be done during the shutdown: Completely drain oil from the system.  Purify and centrifuge the oil.  Examine all oil-bearing components Inspect gear teeth of the gear box. Check for misalignment of the gear box housing. Every two (2) years, the following should be done during the shutdown: Inspect gaps and bearing clearances Inspect alignment. Perform a thorough inspection of the machine including, impeller, bearings, shaft seals, coupling, etc. Perform a major overhaul of the gear box.

Impeller Washing

During normal operation deposits may form on the impeller and in the area between the back of the impeller and the scroll housing.  These deposits may lead to high vibrations in the compressor leading to a blower and plant shutdown.   This problem generally occurs as a result of poor mist elimination at the top of the drying tower.

When an imbalance occurs due to deposits forming on the impeller, the blower must be shutdown and the impeller and casing washed to remove the deposits.

Shutdowns

There may be times when the blower is not operated for extended periods of time such as during the annual plant shutdown.  To prevent damage to the blower the following actions must be taken:

• To prevent corrosion to the bearings, the lubrication system should be flushed with oil once a week for 30 minutes.  This can be done by switching on the electric motor driven auxiliary lube oil pump.
• Cooling water lines should be protected from freezing when ambient temperatures are low.
• The inlet guide vanes should be actuated over its entire range.

Lubrication System

The manufacturer’s recommended oil must be used for the compressor.  Under no circumstances may anti-foaming additives (molybdenum disulphide and/or high pressure additives) be added later.  The use of lubrication oils other than the manufacturer’s recommended oil may void any warranties on the machine.

All attempts must be made to avoid getting dust, dirt, scale, fibres, etc. in to the lubrication oil and system.  Use lint-free cloths for cleaning.

Any new lube oil piping must be pickled prior to installation to ensure the insides are free of scale and dirt.

Any new oil added to the system to make-up for losses must be of the same quality used in the machine.  Oil must never be added directly to the reservoir but must be poured through a fine-mesh screen.  Records should be kept of the oil type, manufacturer, quantity added, filling dates, etc.

Electric Motor

Maintenance of the electric motor will depend on the duty that the motor has been subjected to including the ambient temperature, stopping and starting frequency, atmospheric air quality, etc.  Maintenance on the motor will include such activities as:

• Measurement of insulation resistance to determine the quality of the insulation.
• Cleaning of the motor interior to remove dust, dirt, oil, etc.
• Cleaning and replacement of air filters (if equipped)
• Inspection of bearings

Problems

Impeller Corrosion/Erosion Corrosion or erosion of a blower impeller can occur when there is excessive carry over of acid mist/droplets from the outlet of a drying tower due to poor mist eliminator performance or acid distribution problems.  Deposits may form on the blades resulting in high vibrations and reduced bearing life.  Impellers should be inspected during each plant turnaround and more often if excessive vibrations are observed. Washing the impeller on a regular basis will remove the buildup of solids that lead to high vibrations but the cause of the deposits should be fixed to prevent further buildup. The performance and condition of the drying tower mist eliminators should be monitored.  The easiest way to monitor their performance is to do regular stick tests at the exit of the tower.