Medical Waste Incinerator Process Optimization

Richard A. Hovan
Medical waste incinerators (MWIs) differ from the majority of incinerators about which most regulators and engineers are knowledgeable. Unlike its "big brother," the municipal waste combustor (MWC), the MWI requires a continuous augmented fuel supply to maintain complete combustion and destruction of the primary fuel-medical waste feed.

Typically, natural gas or fuel oil is continuously fed to the combustor chamber where total material and pollutant destruction takes place. The use of fuel has a "cost to operate" that can be minimized by optimizing burner efficiency, thus reducing fuel consumption and emissions output.

The combustion chamber of an incinerator combines the primary air, fuel, and waste. The fuel is introduced through a burner nozzle and is designed to produce a flame front over the full range of operating conditions. Complete incineration is a function of oxygen and temperature levels. However, the higher the temperature and the greater the excess oxygen, the less efficient the MWI will operate. Although reducing excess oxygen improves efficiency, as oxygen decreases, CO starts to form. Excess levels of CO can result in inefficient operation and increased emissions. Operating the unit by minimizing excess O2 while maintaining the CO between 75 to 300 ppm will optimize the efficiency of the burner.

Monitoring O2 and CO as a process application for burner/boiler control has been widely accepted in the utility and industrial markets and has played a strong role in optimizing burner/boiler efficiency. The use of a CO monitor can ensure against emission levels being too high and maximize the efficiency of the burner operation.

Richard A. Hovan is the senior marketing and sales manager of Land Combustion, 125425-B Pearl Buck Road, Bristol, PA 19007