Rotary kiln monitoring

Rotary kilns: continuous production in extreme conditions

A cement rotary kiln is one of the largest and most complex machines in industry. Shell diameter is 4–6 m, length 50–200 m, mass 500–2000 tonnes. Internal temperature reaches 1450°C; external shell temperature 200–350°C.

Clinker kilns run 24/7; planned shutdowns occur 2–4 times per year. An unplanned stop costs $50,000–200,000 per day in lost production plus emergency repair.

Critical monitoring points

Support rollers and bearings

The kiln rests on 2–5 pairs of support rollers. Each pair carries 200–1000 tonnes. Bearings run under constant load, vibration from unbalanced masses and elevated temperature.

Signs of support roller bearing wear:

• Ultrasonic level rise of 6–8 dB — warning
• Bearing temperature above limit — alarm
• Uneven ultrasonic signal — race scoring

SDT340 with high-temperature probes enables checks in service. Critical points are surveyed weekly.

Girth gear and main drive

The kiln is driven through a girth gear on the shell. Mesh with the pinion creates impact loads every revolution.

SDT340 monitors:

• Girth gear tooth condition (pitting, scuffing)
• Gearbox bearings
• Backlash (via ultrasonic level changes)

Bands and flutter

Bands are steel rings on the shell that roll on support rollers. Band flutter (periodic sliding due to thermal expansion mismatch) is detected by SDT340 from its characteristic ultrasonic pattern.

Lubrication with LUBExpert

Support rollers and bearings need systematic greasing. On a large kiln with four supports there are eight bearing stations plus girth gear mesh.

LUBExpert shortens service time and ensures the right grease quantity per point — critical at high temperature where grease viscosity matters.

Artesis EMCM for kiln drives

Artesis EMCM continuously analyzes main drive motor current. Load changes reflect:

• Refractory condition
• Clinker buildup (imbalance)
• Gearbox and mesh defects
• Kiln axis drift from uneven thermal expansion

Results in cement production

Cement plants with SDT + Artesis programs report:

• Avoided emergency kiln stops saving $1–3M per year
• 30–40% lower grease consumption on support rollers
• Maintenance intervals extended from 3 to 5 months
• Timely girth gear wear detection and planned replacement