Preheater-kiln lime calcining systems

Three Metso 18-plunger polygon preheater-kiln systems in Taiyuan, China Proven experience Metso has supplied more than 210 lime calcining systems, over 115 of them as preheater/rotary kiln systems. The worldwide total annual production capacity from Metso-supplied systems exceeds 30 million metric tons per year. The Metso experience encompasses complete plant design including limestone crushing and screening, calcining (of both high calcium and dolomitic limestones), kiln firing, emissions, product handling and storage, and lime hydration. Metso’s worldwide experience and expertise allows for...

Metso lime kiln system features Preheaters The KVS preheater system includes an integral “live” stone storage bin. Stone flows by gravity from the bin to the preheater modules through vertical chutes, (which also provide an air seal between the process and ambient). Kiln exhaust gases enter the preheater at 1010–1095 °C. As these hot process gases pass through the preheater, heat is transferred to the bed of material within. This causes the release of 25–35% of the CO2 from the limestone within the preheater. The partially calcined material is discharged from the preheater by controlled, sequential...

The riding ring of a rotary kiln being re-surfaced in the field Specialized services Coolers Metso’s lime calcining technology includes the KVS/Niems high efficiency contact cooler. With heat recovery efficiencies in excess of 90%, this direct contact, counter-flow heat exchanger provides both extensive cooling of the lime product, and significant preheating of secondary combustion air for the kiln firing system. The kiln burner, the primary heat source for the process, is mounted in the firing hood, which is installed directly above the cooler. The firing hood and cooler are designed to be complementary...

PLC-based control Typical screen graphics for a preheater-kiln lime calcining system Metso designs and supplies its own PLC-based, computerapplied process control system. At the heart of the system is a Programmable Logic Controller (or PLC), which carries out the monitoring and interlocking functions of the control system. Using control programming installed by Metso engineers, the PLC constantly compares actual operating data to pre-established setpoints for “normal” operation, and makes corrective changes to the process as needed to achieve the desired operating conditions. Access to the process...

Metso Minerals Industries, Inc., 350 Railroad Street, Danville, PA 17821, USA, tel +1 570 275 3050, fax +1 570 275 6789, www.metso.com