Incineration continued

ADVANTAGES AND DISADVANTAGES OF POSSIBLE ALTERATIONS TO BASELINE INCINERATION (continued)... 

Misleading also is the idea that vinyl should be harmed from incinerators because it contains heavy-metal additives. This is an evolving issue. Most vinyl products do not contain heavy metals and vinyl is a small fraction in feed to incinerators. Reformulation to replace heavy metals is in progress but some use is likely to continue. Banning vinyl from incinerators does not eliminate this problem. Rather, regulations should specify that incinerator residues (ash) be disposed of appropriately. 

In water-wall incinerators. The internal walls of the combustion chamber are lined with boiler tubes that are arranged vertically and welded together in continuous sections. When water walls are employed in place of refrac toiy materials, they are not only useful for the recovery of steam but also extremely effective in controlling furnace temperature without introducing excess air however, they are subject to corrosion by the hydrochloric acid produced from the burning of some plastic compounds and the molten ash containing salts (chlorides and sulfates) that attach to the tubes. 

In catalytic incineration, there are limitations concerning the effluent streams to be treated. Waste gases with organic compound contents higher than 20% of LET (lower explosion limit) are not suitable, as the heat content released in the oxidation process increases the catalyst bed temperature above 650 °C. This is normally the maximum permissible temperature to which a catalyst bed can be continuously exposed. The problem is solved by dilution-, this method increases the furnace volume and hence the investment and operation costs. Concentrations between 2% and 20% of LET are optimal, The catalytic incinerator is not recommended without prefiltration for waste gases containing particulate matter or liquids which cannot be vaporized. The waste gas must not contain catalyst poisons, such as phosphorus, arsenic, antimony, lead, zinc, mercury, tin, sulfur, or iron oxide.(see Table 1.3.111... 

This subject effects designers since many products have the requirement by regulations or otherwise to use recycled plastics. Different methods are used to recycle materials to provide plastics with a continuing life. Method used is influenced by factors such as costs, quantity involved, weight involved, size and shape, complexity of mixed types of plastics, extended of contamination such as metallic particles, continued availability of material, etc. (Recognize that they can also be used as energy sources through incineration that can be combined with production of electricity and/or hot water for example). 

Complete dissolution of plutonium residues, especially high temperature calcined plutonium dioxide contained in residues such as incinerator ash, continues to cause problems, despite continued research since the Manhattan Project (9). Methods to improve the Rocky Flats system include the use of additives (e.g., cerium) and electrochemistry, other solvents (HCl-SnCl2) as well as high-temperature fusion methods (10). High pressure dissolution, HF preleaching, fluorination, and other methods are being investigated. 

Improvements in the monitoring and operation of incinerators could minimize the accidental release of hazardons efflnents. In particular, fast-acting, continuous, on-line monitors are needed to detect excursions in operating conditions that could lead to toxic emissions. 

Catalytic incineration has been appHed in the abatement of chlorinated VOC emissions in the pharmaceutical industry. The major compounds in the emission mixture are dichloromethane, perchloroethylene, dimethylformamide, oxitol, and toluene. The incinerator operates normally at 400-500 °C, but when emissions contain perchloroethylene the temperature is increased up to 500-600 °C. The emission mixture also contains water, which pushes the selectivity further toward HCl formation instead of formation of CI2. After oxidation, the product gases are washed with NaOH scrubbers. The purification level of over 99% can be achieved with the incinerator, the activity of which has been shown to be very stable after one year of continuous operation [69-71]. 

It is estimated that approximately 15,290 m3 (20,000 yd3) of contaminated soil would need to be excavated and treated. The incinerator would be operated continuously (24 h/d, 365 d/yr), although... 

Continued contamination is curtailed by soil fixation and Incineration migration of contaminated groundwater is curtailed by pump-and-treat... 

Environmental impacts Continued impact from existing conditions Would be some migration of contaminant pluma as part of attenuation process Vapor extraction may affect air quality and odors although it will meet emission standards would be aquifer drawdown during groundwater extraction See Alternative 3 fixation may also affect air quality and produce odors Incineration may affect air quality by producing odors, although if will meet emission standards... 

The specific equipment used for each step depends on the incinerator type and the physical and chemical characteristics of the wastes the incinerator is designed to bum. Wastes are fed into the incinerator in batches or in a continuous stream. Liquid wastes are often pumped and atomized into fine droplets that bum more easily. Solid wastes may be fed into the incinerator in bulk or in containers using a conveyer, a gravity system, or a ram feeder.8... 

Another way to ensure continued satisfactory operation is to retest the incinerator periodically. This would be appropriate if the CERCLA incinerator operates at the site for an extended period of time, or there are other indications that it may not be operating properly. 

Trial bums, with appropriate stack sampling and analysis, and subsequent continuous emissions monitoring are conducted to demonstrate that the incinerator performs as specified. 

Incinerators in existence on May 19, 1980, were allowed to continue burning hazardous waste if the units complied with the Part 265, Subpart O,4 interim status standards. On November 8,1989,... 

A RCRA permit for a hazardous waste incinerator sets operating conditions that specify allowable ranges for, and requires continuous monitoring of, certain critical parameters. Operation within these parameters ensures that combustion is performed in the most protective manner and the performance standards are achieved. These parameters, or operating conditions, include16... 

In addition, the trial bum process for interim status incinerators is different from that discussed previously in this chapter. As interim status units were already in operation on the effective date of the regulations, the facility would submit their trial bum plan for approval without ceasing operation. Once this plan is approved, the facility would conduct the trial bum test (or submit data in lieu of the trial bum) and continue operating under interim status until the final permit is issued. 

As U.S. EPA continues to revise the regulatory program for incinerators in order to adequately protect human health and the environment, the omnibus permitting authority, site-specific risk assessments, and public participation issues have received greater attention. The following discusses both issues in greater detail. 

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