Rotary-kiln incinerator

Thermal Treatment Melhods Advanced Liquid Injection Incineration Cyclm Cyclone Incinerator Rotary Kilns... 

Modular Incineration Rotary Kiln System Consertherm Rotary Kiln Oxidizer Fast Rotary Reactor Incineration Syslem Fluidized Bed Incineration Circulating Bed Combustion Multisolid Fluidized Bed Combustion The Infrared Incineration Systems Shirco s Infrared Incineration System Electric Reactors Advanced Electric Reactor... 

Multiple-chamber incinerators, rotary kilns, and multiple-hearth furnaces are most widely used in industrial waste disposal. 

Fig. 6 is a sketch of a rotary kiln incinerator, illustrating many of the essential phenomena associated with incineration. Rotary kilns are versatile incinerators because of their ability to treat solid, liquid, and gaseous wastes. Solid and liquid wastes are destroyed primarily through establishment of diffusion flames, i.e., flames that surround solid waste particles or droplets or form a flame sheet adjacent to surfaces. 

Fig. 6 Schematic of a versatile waste incinerator. Rotary kiln furnaces are preferred because of their applicability to treat different types of wastes, including solid wastes.

Current disposal methods include liquid injection incineration, rotary kiln incineration, fluidized bed incineration, and air stripping (HSDB 1995), however, data on the efficiency of these methods are lacking. This information will be useful in identifying the media of concern for human exposure and populations at risk of adverse health effects from exposure to carbon disulfide. 

A wide variety of special-purpose incinerators (qv) with accompanying gas scmbbers and soHd particle collectors have been developed and installed in various demilitarisation faciUties. These include flashing furnaces that remove all vestiges of explosive from metal parts to assure safety in handling deactivation furnaces, to render safe small arms and nonlethal chemical munitions fluidized-bed incinerators that bum slurries of ground up propellants or explosives in oil and rotary kilns to destroy explosive and contaminated waste and bulk explosive. 

Rotary Kiln Incinerators. The rotary kiln has been used to incinerate a large variety of Hquid and soHd industrial wastes. Any Hquid capable of being atomized by steam or air can be incinerated, as well as heavy tars, sludges, pallets, and filter cakes. This abiUty to accept diverse feeds is the outstanding feature of the rotary kiln and, therefore, this type of incinerator is often selected by the chemical and waste treatment industries. 

A more simplified description is a unit that combusts materials in the presence of oxygen at temperatures normally ranging from 800 to 1650°C. A typical configuration of an incinerator is shown in Figure 9. Typical types of incineration units that are discussed herein are catalytic oxidation, fluidized beds, hquid injection, multiple hearth furnaces, and rotary kiln. Thermal desorption is also discussed. However, an overview of the main factors affecting incinerator performance is presented first, below. 

Sohd wastes are treated in a soHd waste disposal area to reduce thein volume and or toxicity prior to final disposal in a secured landfill. Combustible wastes can be incinerated in a slagging rotary kiln to reduce volume and toxicity. 

Mass-fired incinerators, with and without heat recovery, for unprocessed wastes rotary kilns for hazardous/containerized and bulk solid/sludge waste... 

Rotary kilns (discussed under the incineration of solids)... 

USATHAMA) completed a trial burn of explosive, contaminated soil in a rotary kiln (Noland, 1984). Soil contaminated from red and pink water lagoons was successfully burned. A transportable rotary kiln yrstem was set up. The technology by Therm-All, Inc., had been used in industry for destruction of solid wastes. The normal screw feed system was not used, due to fear of a soil explosion during the extruded plug feed process. Therefore, the soil was placed in combustible buckets and individually fed by a ram into the incinerator. The feed rate was 300 to 400 Ib/hr and the operational temperature was 1200° to 1600°F in the kiln and 1600° to 2000°F in the secondary chamber. 

Rotary kilns, as described previously, can be used to incinerate materials which can be excavated and fed into the kiln. Vitrification is a process which can be used without removing the soil and is described below. 

Solid wastes arc disposed of by two basic methods. The first is by some type of dumping or landfill procedure the second is by incinerating (burning) the waste. This section focuses on incinerators, namely the rotary kiln, liquid injection, fuidized-bed, and multiple-hearth dc ices, which are the four types... 

The key to efficient destruction of liquid hazardous wastes lies in minimizing unevaporated droplets and unrcacted vapors. Just as for the rotary kiln, temperature, residence time, and turbulence may be optimized to increase destruction efficiencies. Typical combustion chamber residence time and temperature ranges arc 0.5-2 s and 1300-3000°F. Liquid injection incinerators vary in dimensions and have feed rates up to 1500 gal/h of organic wastes and 4000 gal/h of aqueous waste. 

Studies of the incineration of liquid and solid wastes must determine the rates at which hazardous compounds are released into the vapor phase or are transformed in the condensed phase, particularly when the hazardous materials make up a small fraction of the liquid burned. We must be particularly concerned with understanding the effects of the major composition and property variations that might be encountered in waste incinerator operations—for example, fluctuations in heating value and water content, as well as phase separations. Evidence of the importance of variations in waste properties on incinerator performance has been demonstrated by the observation of major smges in emissions from rotary-kiln incinerators as a consequence of the rapid release of volatiles during the feeding of unstable materials into the incinerator. 

Improved methods for the disposal of methyl parathion are being considered. In 1981, methyl parathion was considered as a potential candidate for rotary kiln incineration and fluidized bed incineration (EPA 198 lb). An accelerated degradation process for methyl parathion, which involved reducing the compound in soil with acid and zinc to its less toxic degradates, was found to be effective (Butler et al. 1981b). No recent information on disposal is available. 

The process is basically a rotary kiln design. Waste is first pretreated and then inserted in the rotary kiln, where it is incinerated with air. The chlorinated hydrocarbons are converted into H2O, CO2 and HCl. After that, in a wet scrubber the HCl is recovered as aqueous HCl. If needs be, natural gas or liquid energy carriers can be added in order to reach the necessary high temperatures in the afterburner. 

Direct incineration is mainly used for organically contaminated soil with sufficient concentration that no or little additional fuel is needed. Incineration of contaminated soil in a rotary kiln would result in virtually complete destruction of TCE and diesel fuel. The organic portion of lead dithiocarbonate... 

The Subpart O standards apply to units that treat or destroy hazardous waste and which meet the definition of an incinerator. An incinerator is any enclosed device that uses controlled flame combustion and does not meet the criteria for classification as a boiler, sludge dryer, carbon regeneration unit, or industrial furnace. Typical incinerators1 2 3 include rotary kilns, liquid injectors, fixed hearth units, and fluidized bed incinerators (Table 23.1). The definition of an incinerator also includes units that meet the definition of an infrared incinerator or plasma arc incinerator. An infrared incinerator is any enclosed device that uses electric-powered resistance as a source of heat and which is not listed as an industrial furnace. A plasma arc incinerator is any enclosed device that uses a high-intensity electrical discharge as a source of heat and which is not listed as an industrial furnace. 

Because acrylonitrile is listed as a hazardous substance, disposal of waste acrylonitrile is controlled by number of federal regulations (see Chapter 7). Rotary kiln, fluidized bed and liquid injection incineration are acceptable methods of acrylonitrile disposal (HSDB 1988). Underground injection is another disposal method. The most recent quantitative information on amount of acrylonitrile disposed in waste sites is for 1987. Emissions were 0.9 metric tons in surface water, 152 metric tons disposed through Publicly Owned Treatment Works (POTW), 92 metric tons disposed of on land 1,912 metric tons by underground injection (TR11988). Because acrylonitrile is relatively volatile and is also readily soluble in water, release to the environment from waste sites is of concern. 

Debatox A rotary kiln system for recycling consumer battery materials developed by Sulzer Chemtech. The system first shreds the batteries and then incinerates them. Carbon, plastics, and paper are burnt. Dioxins are destroyed in an afterburner, and mercury is condensed in a scrubber. The residual solids, containing zinc, manganese, and iron, can be recycled by standard smelters. 

Hexachloroethane and waste containing hexachloroethane are classified as hazardous wastes by EPA. Generators of waste containing this contaminant must conform to EPA regulations for treatment, storage, and disposal (see Chapter 7). Rotary kiln or fluidized bed incineration methods are acceptable disposal methods for these wastes. Underground injection may also be used (HSDB 1995). 

Production, Import/Export, Use, Release, and Disposal. Hexachloroethane is not manufactured for commercial distribution in the United States (Gordon et al. 1991 IARC 1979 Santodonato et al. 1985). However, current production as a by-product and import information are not available. Current uses of this chemical and the amounts consumed by each use, including militaiy uses, were not located. This information would be helpful in assessing potential exposure to workers and the general population. The amount of the chemical disposed of by industrial facilities was reported to EPA (TRI93 1995), but information on quantities of hexachloroethane-containing wastes disposed of by military facilities was not located. Rotary kiln or fluidized bed incineration are acceptable methods for disposal of waste containing hexachloroethane (HSDB 1995). 

Rotary kiln incinerators, 13 175-176 Rotary kilns, 15 52-53, 603, 26 611-612 puffing and loss of flame in, 13 182 in thermal waste treatment, 25 833-834 Rotary lobe pumps, 21 73 Rotary molds, 18 50 Rotary regenerative heat exchanger,... 

The rotary kiln technology is quite common in the incineration business. The conversion technology in this case is in the form of a rotating tube, see Figure 22. 

One incinerator that has been evaluated rather extensively and for which test results have been reported is the liquid chemical waste incinerator facility owned by the Metropolitan Sewer District (MSD) of Greater Cincinnati, Ohio (1 ). The MSD facility uses a rotary kiln and liquid injection cyclone furnace to incinerate a wide variety of liquid industrial chemical wastes. The total design heat release rate is 120 million kJ/h (114 million Btu/h). Tests conducted over a wide temperature range ( 900°C to 1300°C) for six Appendix VIII chemicals (carbon tetrachloride, chloroform, hexachlorobenzene, hexachlorocyclo-pentadiene, and hexachloroethane) have shown DREs equal to or very near 99.99%. 

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