EnerWaste International Corp.’s oxydizing system (BOS) is a pyrolysis-based system that decreases emissions and increases affordability. The process is a two-stage system in which the primary stage is batch fed once daily. Capacity is based on the physical size of the primary chamber and on the number of these chambers. Each chamber can be sized from one to over 35 tons of waste each. A common afterburner can be designed to accommodate two or more primary chambers and to allow for future expansion.
A relatively cool and “quiet” sub-stoichiometric (less than theoretical air requirement) environment is maintained in the large waste chambers. The waste burns slowly downward from top to bottom without turbulence or visible flame.
Since the system utilizes a quiet oxidation and not a hot, open flame it doesn’t break down metals, glass or other inorganics. While the solid wastes are being oxidized and converted to gas a “lazy” gas stream flows into the high temperature afterburner for complete destruction.
At the end of a cycle, the waste is normally reduced by more than 95 per cent with only glass and metals remaining (intact and sterilized) that are easy to separate from the ash after oxidation. The BOS has also demonstrated its ability to successfully strip copper or aluminum wire for recycling.
The highly localized combustion temperatures of old controlled air systems produce ash with awkward clinkers and three to five per cent unburned organic material. The BOS system has no clinker and a burnout of almost 100 per cent, which leaves an extremely clean, white-colored ash containing almost no hazardous organics. The bottom ash that remains in the chamber has passed the U.S. EPA’s Toxic Content Leaching Procedure (TCLP) test.
Except for start-up and shutdown, the heat value from the waste burned is normally sufficient to maintain operating temperatures. In contrast to the old controlled air systems, there aren’t complex feeders and ash removal systems. This simplicity and lack of moving mechanisms greatly minimize maintenance.
The system requires only one operator and on a part-time basis. The system can be loaded daily and it takes approximately one hour — the rest of the time it runs unattended on automated computer control.
By contrast, the old controlled air incinerators required constant attention (24 hours a day) and loading (every 15 to 30 minutes). Even with “automatic” hydraulic loading and ash removal, constant tending is required. At least three full-time operators are required for controlled air systems.
Heat recovery options can be employed as well — including steam, hot water, hot air, or electricity — and can be added to the system at any time.
The BOS accepts full size, fully loaded pallets and bailed waste — even couches and large construction waste that can be loaded by forklift. A standard chamber is long enough to load debris over 10 feet in length without manual size reduction. By contrast, a controlled air incinerator can accept only pieces no larger than the hydraulic feeder hopper.
Emissions are kept exceptionally low, an important improvement over old incinerators. Since the BOS is loaded only once per day, there are no disruptions of the process during operation. The burning bed is not agitated two or three times every hour as it is with other systems that create emission upsets. The slow and low temperature environment minimizes particulate, heavy metals and many noxious gasses.
The low temperature environment also results in the elimination of slagging glass (which reduces refractory and system maintenance) greatly reduces scrubbing costs or total elimination of downstream emission control equipment.
Tom Dutcher is president of EnerWaste International Corp. based in Vancouver, British Columbia and Bellingham, Washington.