Finding the missing link
In 2015 Çimsa Çimento’s Mersin plant, Turkey, suffered an increasing number of cyclone blockages, causing severe interruptions to the facility’s grey cement Line 1. After unsuccessful attempts to find the reason for the blockages, a kiln inlet process gas measurement system from sick was installed to provide the missing link between the sulphur content in the kiln process gases and unwanted production downtime. By Felix Bartknecht, SICK AG, Germany, and Sezin Arıkan, Çimsa Çimento Mersin, Turkey.
Figure 1: SCP3000 high-temperature gas extraction probe
Çimsa Çimento’s Line 1 at Mersin produces 1.25Mta of grey cement and uses a four-stage double-string cyclone preheater in combination with an 82.5m-long and 5.25m-diameter rotary kiln. Like most cement plants in Turkey, the Mersin works uses petcoke as its main fuel for the production of grey Portland cement. With a sulphur content of up to seven per cent, petcoke can cause severe clogging, build-ups and ring formation in the combustion and heat transfer zones of the process (ie rotary kiln, riser duct and cyclones). This obstructive process is affected by different variables such as the concentrations of alkali, sulphur and chlorine compounds. These volatile elements can be released from fuels as well as raw materials in heat transfer zones and tend to condense at colder spots of the pyroprocess. To avoid build-ups the raw meal’s sulphur-alkali ratio, temperature profile and local hot spots in the kiln have to be regularly controlled. Additionally, completeness of combustion, raw material surface porosity as well as retention time of the hot meal and process gases are checked continuously.
