Most industrial processes produce waste. Some of it is hazardous and presents dangers to public health and environment, if not managed properly.
Most notably, hazardous waste is associated with production of gasolines, cosmetics, detergents, pharmaceuticals, paints & cleaning products, garden pesticides, cell phones, TVs, computers and even light bulbs.
Waste can be liquid, solid, contained gas or sludge. Then too there are the “by-products” of production processes and the discarded commercial products themselves, like cleaning fluids or pesticides.
Corporate America, mid-sized companies and even the small facilities and workshops in recent years have reduced or recycle process wastes. Despite their best efforts, more than 200 million tons of hazardous waste are generated each year.
In years past, hazardous waste was consigned to regular landfills, resulting in incidences of materials seeping into the ground and nearby water sources.
Today hazardous waste is often destroyed in an incinerator. Incineration not only reduces the amount of hazardous waste, but may also generate energy through the process gases released.
In the U.S., modern hazardous waste incineration already is a widespread and common technology.
Hazardous waste destruction in incinerators has been determined by the U.S. Environmental Protection Agency (EPA) to be the “best demonstrated available technology” (BDAT) for most organic hazardous waste because the incineration process safely and effectively destroys the hazardous constituents in waste. When done right, incineration eliminates the toxic constituents in hazardous waste and reduces waste volume.
Hazardous waste combustors or incinerators are regulated under the Clean Air Act and the Resource Conservation and Recovery Act. The Clean Air Act mandates reductions in emissions of some of the most hazardous air pollutants.
Incineration converts waste into ash, flue gas and heat. Ash is produced by the waste’s inorganic substances and may be solid lumps or particulates carried by the flue gas. Flue gases can be dispersed into the atmosphere only after being cleaned of gaseous and particulate pollutants. In some instances, the heat generated by the incineration process can be used to generate electric power.
Incinerators reduce the solid mass of the original waste by 80 to 85 percent and volume by 95 to 96 percent. While incineration does not completely eliminate the need for landfilling, it does reduce the volume of waste necessary for disposal. Incineration has especially strong benefits for the treatment of specific types of waste, such as clinical wastes and hazardous wastes where pathogens and toxins can be destroyed by extremely high temperatures.
A typical hazardous waste incinerator consists of a rotary kiln, an afterburner and a means to control air pollution. Both solid and liquid wastes are introduced into the rotary kiln, in which the temperature is usually higher than 1,800 degrees F. This extremely high temperature is maintained through the use of the heat content of liquid wastes or the introduction of supplemental fuels, such as natural gas, into the chamber.
A Vulcan Hazardous Waste Incinerator, for example, is a 12’ diameter x 20’ long rotary drum incinerator. The refractory-lined rotary drum is capable of operating at up to 2,600 degrees F.
The kiln rotates slowly to ensure that the solid wastes are exposed on all sides to the heating elements. A large fan draws air into the system to increase combustion efficiency.
The ram feeder can be automatically or manually cycled through a refractory lined charging into the combustion chamber. The primary combustion chamber consists of the rotary drum and a 20 MMBtu burner which is controlled based on sensing input placed in the ductwork between the primary and secondary combustion chambers. Ash from the primary combustion unit is discharged through a refractory lined valve placed in the discharge bridging.
Final propitious outcomes
The vapor from the primary combustion chamber is pulled through refractory lined ductwork to a secondary combustion chamber, where the vapor is oxidized at temperatures up to 2,600 F for at least two seconds. The vapor from the secondary combustion chamber is pulled through a pre-cooler, where the temperature is reduced to approximately 1,400 F.
From the pre-cooler, the vapor is pulled through a plume eliminator, which also acts as a heat exchanger. In the plume eliminator, fine dust particulates are removed, and the vapor is cooled to approximately 700 F. Vapor from the plume eliminator is pulled through an after-cooler where it is further quenched, prior to entering a Venturi scrubber and absorption tower, used in controlling air pollution.
Incinerating hazardous waste decreases the load placed on landfills and prevents potentially dangerous materials within the waste from leaching out and polluting the surrounding environment. Through incineration, hazardous wastes can be safely and efficiently discarded.