Combustion system and method for burning fuel with a variable heating value

摘要

The preferred embodiment of the invention disclosed herein includes apparatus for and steps of separating glass, metal and other generally non-combustible material from refuse to provide a volume of generally combustible refuse, shredding this volume of combustible refuse into relatively small particles, mixing these particles with primary combustion air and conveying the resultant mixture of air and particles into a combustion chamber. The combustion chamber is preheated by auxiliary heating means to a temperature sufficient to cause the mixture to be self-igniting in the combustion chamber. Secondary combustion air is fed to the combustion chamber at spaced-apart points within the chamber for assuring a complete combustion process. This chamber is maintained under a negative pressure by a fan downstream and the combustion gases are thus caused to flow from the combustion chamber to an associated device utilizing the heat energy, for example, a steam boiler, and from the steam boiler, the gases are exhausted through a stack to the atmosphere. Oxygen measuring means is located on the discharge side of the boiler for measuring the amount of excess oxygen discharged to the atmosphere. In response to this measurement, the feed rate of the shredded particles of refuse is adjusted to maintain a substantially constant amount of excess oxygen in the combustion gases whereby the B.T.U. output is controlled.