Final Report: Low-Cost Feedback Pollutant Control for Small Industrial BoilersEPA Contract Number: EPD05040
Title: Low-Cost Feedback Pollutant Control for Small Industrial Boilers
Investigators: Silver, Joel A.
Small Business: Southwest Sciences Inc.
EPA Contact: Manager, SBIR Program
Project Period: March 1, 2005 through August 31, 2005
Project Amount: $70,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2005) RFA Text | Recipients Lists
Research Category: SBIR - Air Pollution , Air Quality and Air Toxics , Small Business Innovation Research (SBIR)
Boilers, furnaces, and process heaters account for more than three-quarters of the total energy consumed by U.S. manufacturing industries. Small industrial boilers are an important class of pollution sources, particularly for generation of particulates and carbon monoxide (CO). Performance targets for boilers require emission reductions coupled with improving performance with lower life-cycle costs. Recently, the U.S. Environmental Protection Agency signed the National Emission Standards for Hazardous Air Pollutants for industrial, commercial, and institutional boilers and process heaters. Among other requirements, it sets out CO, hydrogen chloride, metal, and particulate matter (PM) emissions requirements for small oil- and coal-fired boilers. Among the items of highest priority to achieve these restrictions is the need for simple feedback control sensors to monitor these combustion flames and to adjust the control inputs in real time to continuously maintain optimized performance.
In this Phase I research project, Southwest Sciences, Inc., studied the development of a low-cost sensor for feedback control systems that can be used with individual burners. This microelectromechanical systems (MEMS) mirror nondispersive infrared (NDIR) sensor uses miniaturized light sources and detectors with broadband gas-correlation optical absorption to make measurements of CO that will be used to regulate combustion fuel-air ratios. Retrofit or new placement of these sensors on each burner will increase the efficiency (providing cost savings) and more effectively meet regulatory regulations for minimizing pollutant emissions. Expected benefits of this approach would include reduction of PM, nitrous monoxide, and CO while improving boiler operating efficiency.
A MEMS-mirror-based NDIR gas sensor, designed for monitoring CO at better than 10-ppm levels in cooled post-combustion gases, was designed and built. This breadboard version was tested using calibrated flows of CO, as well as post-combustion gases sampled from a diffusion burner flame. The compact IR source worked well and the flame sampling was successful. Due to excessive optical losses in this Phase I sensor, desired detection sensitivity levels were not achieved. Nevertheless, the limiting factors were identified, and given the better resources of a Phase II project, Southwest Sciences believes that this approach should permit the development of a much smaller, compact, and lower-power NDIR gas correlation filter sensor for use with a variety of gases.
This project demonstrated the potential for developing a smaller, simpler NDIR CO sensor. Southwest Sciences believes that the major factors to be addressed have been identified and could be successfully incorporated into a Phase II prototype. This sensor could be used for virtually any simple IR-absorbing gas, so that multi-gas versions also could be developed. The key to successful commercial introduction is to lower the cost of components, via innovative designs and through the advantages of manufacturing in volume. Southwest Sciences believes that these challenges can be successfully addressed.