Oxygen lancing methods for industrial processes

摘要

Oxygen is often used in industrial combustion processes to improve emissions, reduce fuel cost and/or increase production. As opposed to simply enriching combustion air with oxygen, oxygen lancing is utilized when targeting the oxygen to a specific part of the combustion process is beneficial.This work compares 2 methods of lancing oxygen into a process, the first comprising a sonic velocity jet of ambient temperature ("cold") oxygen and the second an oxygen jet heated to temperatures exceeding 1500 degrees C ("hot oxygen"). The hot oxygen jet is accelerated to a velocity 2-4 times higher than is possible with comparable cold oxygen jets. Simple jet theory is used in conjunction with detailed kinetic simulations to investigate differences in lance reactivity and effectiveness. A range of conditions is investigated, including oxygen preheat temperature, ambient gas conditions and turndown capability. In all cases, hot oxygen lancing provides better mixing capability than cold oxygen lances. In addition, the increased reactivity of hot oxygen proves more effective than cold oxygen when reacting with ambient gases.A real world comparison of cold and hot oxygen lancing into a cement kiln for CO emission reduction is also presented. In practice, a non-optimized hot oxygen lance reduces CO emissions from the flue gas by more than 25% over a fully optimized cold oxygen lance.