Fluidized bed incinerators

The tests were conducted with the knowledge of the importance of post-combustion, low-temperature reactions, and represented an advance on the 1987 GCP study. The results of the trials on cement kilns, lightweight aggregate kilns, hazardous waste incinerators, liquid injection incinerators, fluidized bed incinerators, fixed hearth incinerators and hazardous waste boilers were summarized as follows 6... 

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. 

Based on the type of thermal destruction process selected, there are several different commercial designs and configurations of the reactor that have been utilized for a particular application. Some of the most commonly used technologies include rotary kilns, starved air incinerators, fluidized beds, mass-bum incinerators, electrically heated reactors, microwave reactors, plasma, and other high-temperature thermal destruction systems. Recent advances include gasification and very high temperature steam reforming. 

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. 

T. C. Ho and co-workers, "Metal Capture During Fluidized Bed Incineration of Wastes Contaminated with Lead Chloride," presented at the... 

F/uidi ed-BedIncinerator. Fluidized-bed incinerators are employed in the paper and petroleum (qv) industries, in the processing of nuclear wastes, and the disposal of sewage sludge. These are quite versatile and can be used for disposal of soflds, Hquids, and gaseous combustible wastes. 

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. 

Incineration can be accompHshed ia multiple-hearth furnaces, ia which the sludge passes vertically through a series of hearths. In a fluidized-bed sludge, particles are fed iato a bed of sand fluidized by upwardly moving air. 

Technology Description Fluidized bed incinerators utilize a very turbulent bed of inert granular material (usually sand) to improve the transfer of heat to the waste streams to be incinerated. Air is blown through the granular bed materials until they are "suspended" and able to move and mix in a manner similar to a fluid, i.e., they are "fluidized".In this manner, the heated bed particles come in intimate contact with the wastes being burned. The process requires that the waste be fed into multiple injection ports for successful treatment. Advantages... 

Residuals Produced Fluidized bed incineration produces no separate ash as such, but solids are carried over in the gas stream and will require removal. Residuals from the air pollution control devices may require additional treatment prior to disposal. 

Corrective Action Application Fluidized bed incineration has been used to incinerate municipal wastewater treatment plant sludge, oil refinery waste, some pharmaceutical wastes, and some chemical wastes including phenolic waste, and methyl methacrylate. Heat recovery is piossible. 

Corrective Action Application Circulating fluidized bed incinerators are ready for full-scale testing under the EPA SITE Program. A unit is now in the RCRA permitting process. 

Fluidized-bed process incinerators have been used mostly in the petroleum and paper industries, and for processing nuclear wastes, spent cook liquor, wood chips, and sewage sludge disposal. Wastes in any physical state can be applied to a fluidized-bed process incinerator. Au.xiliary equipment includes a fuel burner system, an air supply system, and feed systems for liquid and solid wastes. The two basic bed design modes, bubbling bed and circulating bed, are distinguished by the e.xtent to which solids are entrained from the bed into the gas stream. 

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 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. 

The multiple-hearth incinerator (Fig. 16-6) can accept sludges containing between 60 and 75% water. The operating costs run between 0.50 and 5.00 per ton of dry solids, with total costs between 8 and 14 per ton. Design information is given in reference 62. When the sludges contain more water, fluidized-bed incinerators are sometimes used. Their operating costs run between 11 and 21 per ton of dry solids and capital costs are 15/ton.6 See reference 63 for more details. All incinerators must have the proper air-pollution abatement devices attached. 

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. 

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). 

Fluidized-bed gas-phase reactor, in Spherizone technology, 20 543-544 Fluidized-bed incinerators, 13 176-177 Fluidized-bed process technology, butane-based, 15 502-504... 

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