ICAL, located in São José da Lapa city in Minas Gerais state, Brazil, and one of most important lime factory of South America, has one of most advanced world technology in grit, natural lime and hydrated lime with high calcium concentration. Lime is a caustic infusible white substance that consists of calcium and oxygen, and is obtained by heating limestone until it crumbles to powder, and it is used in making cement and fertilizer. The company decided to install a modern automation system for its lime production.
There are four main industrial ovens heating the limestone, three vertical and one horizontal style. Pressure, temperature and flow combustible gas of them, are performed by Smar PA devices. Each oven is controlled by a S7-400 PLC and one S7-300 PLC controls the energy management, lime unloading and also the oven calcareous rock providing as well as the lime for the storage silos. Smar has supplied more than 100 field devices for a PROFIBUS PA compliant process automation solution for lime production at ICAL. Pressure and temperature transmitters, as well as positioners and “Current to Profibus PA”- converters from smar are responsible for the process automation involved in the lime stone heating.
All communication between remote I/O and the CPUs is done via optical fiber and the DP side works at 1.5Mbits/sec. The PA devices are are integrated into PROFIBUS DP system using link devices, segment couplers DP/PA and masters from Siemens. All system is integrated into STEP7 from Siemens. All PA devices, were performed from the control room using PDM engineering tool, which allows the users remotely make the PA devices configuration, calibration and the monitoring across the entire fieldbus network.
System interoperability and all benefits were confirmed and the plant is in operation since beginning of year 2001. During 2003, one more industrial oven was implemented using PROFIBUS Technology. The customer is totally satisfied with the system and now is taking advantages of this open protocol.