An Integrated Cullet/Batch Preheater System for Oxygen-Fuel Fired Glass Furnaces

The general principles, performance, and economics of cullet/batch preheating, using an advanced raining-bed preheater technology developed by Tecogen during a GRI sponsored development program, is described. The raining bed heat exchanger technology provides high heat transfer effectiveness in a compact unit. Batch and cullet, falling freely through the heat exchanger, increase in temperature as they come in direct contact with rising hot combustion gases. The raining bed concept provides important advantages over other preheating methods. Among the advantages are counter-current heat exchange, short residence time, no stored material capacity in the heat exchanger, small footprint, and ease of retrofit onto existing furnaces. Of primary importance is the lack of an inventory of culletlbatch material within the heat exchanger. Material falls freely through the system eliminating the possibility of plugging. The performance of the separately fired pilot unit is attractive, with demonstrated 1000°F batch/cullet provided with a 1300°F inlet temperature. One to four year payback periods are projected for the four furnace systems evaluated.