Implementation of emerging technologies for NOx reductions

Abstract

Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.

The U. S. manufacturing sector uses more energy for steam generation than for any other single purpose. In 2002, steam accounted for 31% of total U. S. manufacturing energy consumption. This high-energy demand in part reflects the reliance on an aging U. S. industrial boiler population employing designs that conceptually vary little from those used at the end of the 19th century. As such, new developments are limited and have offered only incremental gains in operational efficiency. The U. S. manufacturing sector utilizes more than 33,000 boilers with capacities greater than 10 million Btu/hr. Of these, more than 80% were purchased prior to 1978, with the largest share purchased in the 1960’s. However, an important window of opportunity to reduce steam generation energy use will open to U. S. manufacturers as they begin to replace their aging stock of existing industrial boilers nearing retirement. Researchers are working to develop new, breakthrough steam generation technologies that could potentially save U. S. industry billions of dollars per year in operating costs and substantially lower associated environmental impacts. By utilizing a unique boiler geometry incorporating a twostage fire tube design and heat recovery system that are both compact and highly efficient (>94% HHV efficiency), First Generation Super Boilers will offer up to 25% increases in steam generation efficiency and occupy substantially reduced footprints relative to their conventional counterparts. Efficiency gains alone could result in total U. S. manufacturing energy cost savings of approximately $6 billion per year. Reduced footprints also enable new opportunities for boiler modularization. In addition, the First Generation Super Boilers will integrate several novel technologies to achieve extraordinarily low emissions NO<5 ppmv, aiding in compliance with the stringent emissions regulations. During the past three decades, several research efforts have been directed to find solutions for NOx reductions. The major NOx emission sources are from vehicles and industrial boilers. Power plant smokestacks are a significant source of dangerous pollutants, including nitrogen oxides (NOx), sulfur dioxide (SO2), and sooty particles that cause unhealthy ozone and particulate pollution in communities across the nations. Industrial boilers account for 25% of NOx that is emitted worldwide. National emission of NOx over past few years has increased by about 20% whereas all other pollutants have decreased since the implementation of Clean Air Act of 1970 which is a United States Federal law that requires the Environmental Protection Agency (EPA) to develop and enforce regulations to protect the general public from exposure to airborne pollutants that are known to be hazardous to human health. The Industrial Technologies Program (ITP) of the U. S. Department of Energy (DOE) has developed several energy efficient programs such as Best Practices Tools and Energy Efficient Technologies including NOx and Energy Assessment Tools, which help manufacturers to implement, assess and analyze NOx emissions, and energy efficiency improvements. With the help of these tools we can compare how various technology applications and efficiency measures affect overall costs and reduction of NOx and also select the best method for reducing NOx in a system. In this paper, an application of NOx and Energy assessment tools to a natural gas boiler is discussed. NOx reduction analysis using current generation low NOx burner, Next generation ultra NOx burner, and Selective catalytic reduction is performed and results are compared. The details of the application to NxEAT and its advantages like reduction of NOx emissions in the environment are discussed.