Energy Efficient Microwave Hybrid Processing of Lime for Cement, Steel, and Glass Industries

Abstract

that a production size MAT rotary calciner was not feasible, and a different approach was adapted. The concept of a microwave post heat section located in the upper portion of the cooler was devised and well received by the industrial lime company and an industry expert. Commercialization of this technology will require 1) continued pilot scale calcining demonstrations, 2) involvement of lime kiln companies, and 3) involvement of an industrial microwave equipment provider. Ceralink identified two builders of lime kilns whom could be approached to partner with for continued technology and equipment development. Eventually, Ceralink would plan to license and transfer the technology to the kiln builders once the technical aspects are finalized. The lime company could then implement the MAT post heating sections in new builds and pursue retrofit of existing lime kilns in order to improve efficiency. Retrofits would likely be attractive to lime manufacturers, as the purchase of a new lime kiln is on the order of a $30 million dollar investment, where as a MAT retrofit might be on the order of $1 million. Ceralink would receive a royalty from the kiln builder. Current scale-up designs indicate that four 100kW microwave generators (915 MHz frequency) will be required to provide sufficient energy to a chute measuring 6ft in diameter and 4 ft. long to finish calcining the limestone before the limestone is cooled. This is scale for a production size rotary calciner with 600 ton/day output. Ceralink has identified a microwave equipment supplier who could supply the required microwave equipment and engineering work to assist with design and integration.

Microwave vs conventional porcelain firing: Macroscopic properties

“…3,5,14,15 Among various studies, developed mainly in the last three decades, the main attributes of microwave firing are shorter processing times, lower firing temperatures, higher energy efficiency, and lower emissions of harmful gases to the atmosphere. 2,3,16,17 Higher limestone decomposition rates and a 34% processing time reduction were achieved with Microwave Assist Technology (MAT), 18,19 lowering the energy consumption by 36%. A 15-m industrial tunnel kiln prototype that uses MAT technology is presented in Ref.…”

“…Concerning the product quality, microwave firing usually leads to products with similar or even better quality than those conventionally fired 3,5,14,15 . Among various studies, developed mainly in the last three decades, the main attributes of microwave firing are shorter processing times, lower firing temperatures, higher energy efficiency, and lower emissions of harmful gases to the atmosphere 2,3,16,17 . Higher limestone decomposition rates and a 34% processing time reduction were achieved with Microwave Assist Technology (MAT), 18,19 lowering the energy consumption by 36%.…”