In order to remain competitive in the global market, energy intensive combustion processes must reduce costs. Air-natural gas combustion is used in many of these processes including heating and melting of glass and metals. These applications are summarized with respect to natural gas consumption and energy efficiency. Oxygen enrichment can increase furnace productivity and reduce operating costs through improved energy efficiency. Commercial air-natural gas burners were shown to be generally limited to 30% enrichment. Since the maximum benefits of oxygen enrichment (high flame temperature and NOx minimization) are achieved with 100% oxygen, a simple retrofit technology was developed to convert air-natural gas burners to fire oxy-fuel. The technology was tested in a ladle preheating process and a glass melting furnace where increased production and fuel savings were observed. In the glass furnace, burner survivability was improved through water cooling. NOx emissions from heating and melting processes have become a significant environmental issue. A computer-based mathematical model was developed to predict the effect of burner firing conditions on NOx levels. The model currently predicts values higher than experimentally observed, but the trend is correct. The data show that conversion of a furnace to 100% oxygen-natural gas can dramatically reduce NOx emissionsmore » to well within existing regulations. « less