A new method of reducing NOx emissions from Heat Treatment Furnaces

摘要

A new method of reducing NOx emissions from heat treatment furnaces has been developed using a fuel modification technique that involves mixing non-combusting media, typically flue gases, with the fuel, prior to combustion. This method has previously been applied, successfully, in process burners in the refining and petrochemical industries as well as in boiler burners. The method is very versatile and can be adapted to many other combustion processes. The advantages of the new method are that, significant NOx reduction can be achieved with existing burners without modifications in many cases, and with modifications to only the inlet gas nozzle in others. Heat transfer performance is not adversely affected and in some cases more uniform temperature distributions are achievable because of reduced peak flame temperatures. No moving parts are used and no additional fan capacity or high temperature fan/impeller is required. The fuel modification method was applied to a full scale Radiant Tube Burner with a simulated furnace environment, and evaluation tests were carried out in the John Zink Company's combustion test facility. Various quantities of flue gas addition at various heat releases and air temperatures were studied. Reduction in NOx emissions, distribution of tube metal temperature and flame stability were observed. This paper will discuss the theory, experiments, observations and the conclusions derived regarding application of fuel modification to Radiant Tube Burners.