Technical specification Metso pebble lime cooler operation The Metso Pebble Lime Cooler, based largely on a previous L. H. Niems design, is a proven, efficient piece of heat transfer equipment. Its primary purpose, along with that of its associated discharge feeders, is to cool the material discharging from the rotary kiln to a temperature that can be tolerated by the product take-away belt conveyor, all the while maintaining the material discharge rate required for the desired rate of lime production. To accomplish this several PLC-based, “closed loop” (or automatic) controls are employed. In order to maintain an even and continuous transfer of heat within the cooler, two basic conditions must exist: a fairly constant packed bed of material in the cooler and a fairly constant flow of cooling air throughout the bed. To maintain an optimum bed of material within the cooler an automatic level control is used. A microwave (or “radar”) type of level sensing device is installed near the top of the cooler to sense the relative height of the material bed. (See Figure 1, below.) The height of the bed is typically set to be controlled within a high-low range of about 6 inches. Rotary Kiln Level Sensor © Metso Corporation, TS Metso pebble lime cooler 15-01-en Firing Hood Cooler is directly below, beneath concrete floor, out of view. Figure 1. Typical cooler level sensor installation For more information, contact your local Metso representative. www.metso.com Metso Minerals Industries Inc. 350 Railroad Street, Danville, PA 17821-2046, USA, Phone: +1 570 275 3050, Fax: +1 570 275 6789Specifications in this document are subject to change without notice. Product names in this publication are all trademarks of Metso Corporation.

Firing Hood Cooler Level Sensor mounted this side out of view Oversize Material Discharge Cooler © Metso Corporation, TS Metso pebble lime cooler 15-01-en Cooler Discharge Feeders (4) Figure 2. Typical firing hood / Cooler assembly For more information, contact your local Metso representative. www.metso.com Metso Minerals Industries Inc. 350 Railroad Street, Danville, PA 17821-2046, USA, Phone: +1 570 275 3050, Fax: +1 570 275 6789Specifications in this document are subject to change without notice. Product names in this publication are all trademarks of Metso Corporation. Technical specification...

With the above two control loops functioning, a ”coarse” control of heat transfer is maintained. The ”fine” control is maintained through an additional closed loop control in the programming. © Metso Corporation, TS Metso pebble lime cooler 15-01-en Two thermocouple type temperature sensors are installed in each of the four cooler discharge spouts. The temperatures obtained by each pair of thermocouples are averaged and reported as the material discharge temperature for each spout. In a perfect world the temperature of the material discharging from each of the four cooler discharge points would...

© Metso Corporation, TS Metso pebble lime cooler 15-01-en To summarize the function of the cooler discharge feeders… They cycle ”on” and ”off” as a group to control the level of material within the cooler and in turn, the desired rate of production. They speed up or slow down, individually, to maintain the desired discharge temperature at each discharge point, when they are ”on”. The ”primary” control over cooler operation is the level control. Control of the temperatures at the four material discharge points is considered the ”secondary” control. The more often the production rate of the calcining...