Flue waste incineration

Optimized modern dry scrubbing systems for incinerator gas cleaning are much more effective (and expensive) than their counterparts used so far for utility boiler flue gas cleaning. Brinckman and Maresca [ASME Med. Waste Symp. (1992)] describe the use of dry hydrated lime or sodium bicarbonate injection followed by membrane filtration as preferred treatment technology for control of acid gas and particulate matter emissions from modular medical waste incinerators, which have especially high dioxin emissions. 

Particle size distribution relating to gas cleaning is well understood in the industry. This section deals with general rules of thumb. Certain important issues not included in this section are flue gas desulfurization, flue gas denitrification, hazardous waste gas cleaning, waste incineration gas cleaning, and removal of CO2 from flue gas. All these topics have special requirements, which must be considered separately in the design process. 

Mowrer 1,1 Nordin (1987) Characterization of halogenated organic acids in flue gases from municipal waste incinerators. Chemosphere 16 1181-1192. 

Laijava K, Laitinen T, Vahhnan T, Artmann S, Siemens V, Broekaert JAC, Klockow D. 1992. Measurements and control of mercury species in flue gases from liquid waste incineration. Int J Anal Chem 149 73-85. 

Inhibition technology also has been used recently by two other groups. Urea as an aqueous solution added to the fuel has been found to be very effective as an inhibitor of PCDD/F in a pilot and technical plant. Furthermore, other A -compounds and A-compounds, such as sulfur dioxide, ammonia, dimethyla-mine, and methyl mercaptan sprayed as gaseous inhibitors in the flue gas, seem to be a promising technique for preventing the formation of PCDD/F in waste incineration. 

The flue gas from municipal waste incinerator boilers contains SO2, and HCl. To remove these harmful components simultaneously by dry process, electron beam treatment method was investigated. The pilot-scale test was conducted in Matsudo, Japan, in 1992 with a flue gas of 1000 m /hr [34]. Recently, dioxins, namely, poly-chlorinated-di-benzo-paradioxins (PCDDs) and poly-chrorinated-di-benzo-furan (PCDFs), from incinerators have become a very serious problem because of their high toxicity. Pilot-scale tests to decompose dioxins by electron beam irradiation were conducted in Karlsruhe, Germany [35], and in Takahama, Japan [36], using almost the same capacity of flue gas, 1000 m /hr. Very promising results were obtained with decomposing more than 90% of dioxins. 

Zimmerman, R., Heger, H.J., Kettrup, H.J., Boesl, U. (1997) A mobile resonance-enhanced multiphoton ionization time-of-flight mass spectrometry device for online analysis of aromatic pollutants in waste incinerator flue gases first results. Rapid Commun. Mass Spectrom. 11 1095-1102. 

Llobet, J.M., Schuhmacher, M. and Domingo, J.L. (2002) Spatial distribution and temporal variation of metals in the vicinity of a municipal solid waste incinerator after a modernization of the flue gas cleaning systems of the facility. Science of the Total Environment, 284(1-3), 205-14. 

Shih and Lin (2003) investigated the solidification/stabilization of arsenic-rich flyash from an abandoned copper smelter in northern Taiwan. The flyashes (2-40 % total arsenic, mostly as As(III)) were collected from three flue gas discharge tunnels. Extremely high cement dosages (cement/waste mass ratio of greater than 6) were required to stabilize the wastes so that they would pass the US TCLP for arsenic (<5 mg L 1 Appendix E). (The TCLP is often used in research outside of the United States.) Cement dosages could be reduced and the mixtures would still pass the TCLP for both arsenic and lead if municipal waste incinerator flyash was added. Lime alone was able to stabilize arsenic and pass the TCLP however, the leachates exceeded the TCLP lead standard of 5mgL 1. The immobilization of arsenic in lime may be due to the formation of sparsely water-soluble calcium arsenites and arsenates, such as CaHAsC>3 //1LO or Ca3(AsC>4)2 H20, where n > 0 (Shih and Lin, 2003, 692). 

Lurgi Energie und Umwelt GmbH, International Symposium Separation and Treatment of Pollutants from Waste Incineration Flue Gases, Frankfurt, September 1993. 

Chevalier, J., Rousseaux, P., Benoit, V, and Benadda, B., Environmental assessment of flue gas cleaning processes of municipal solid waste incinerators by means of the life cycle assessment approach, Chem. Eng. Sci, 58, 10 (May) 2053-2064, 2003. 

Mercury is one of a number of toxic heavy metals that occur in trace amounts in fossil fuels, particularly coal, and are also present in waste materials. During the combustion of fuels or wastes in power plants and utility boilers, these metals can be released to the atmosphere unless remedial action is taken. Emissions from municipal waste incinerators can substantially add to the environmental audit of heavy metals, since domestic and industrial waste often contains many sources of heavy metals. Mercury vapor is particularly difficult to capture from combustion gas streams due to its volatility. Some processes under study for the removal of mercury from flue gas streams are based upon the injection of finely ground activated carbon. The efficiency of mercury sorption depends upon the mercury speciation and the gas temperature. The capture of elemental mercury can be enhanced by impregnating the activated carbon with sulfur, with the formation of less volatile mercuric sulfide [37] this technique has been applied to the removal of mercury from natural gas streams. One of the principal difficulties in removing Hg from flue gas streams is that the extent of adsorption is very low at the temperatures typically encountered, and it is often impractical to consider cooling these large volumes of gas. 

Orconlent in fiue gas. The first part of this research has been carried out with Cl-VOCs in air (21 vol % O2 content) but the catalysts here tested would be used in flue gas downstream from waste incinerators, which usually have 02-contents (regulated by laws) of 7-11 vol%. To know the influence of the 02-content in the flue gas, some oxidation tests were carried out with the same catalyst(s) but with the Cl-VOC diluted in air and in a simulated flue gas containing 10.7 vol % O2 only. 

It is well known that in the stack or exit gas of waste incineration plants there is not only one VOC or Cl-VOC but a mixture of them. Some preliminary tests were made introducii a second hydrocarbon mixed with TCE. Heptane and toluene were selected as key aliphatic and aromatic hydrocarbons. The activity of the catalyst was exp. determined with and without these hydrocarbons as well as with and without steam in the flue gas. 

Narvaez I., Corella J., Aznar M. P. (1993) New Processes for Flue Gas Cleaning in Solid Waste Incinerators . Ingenieria Quimica (Madrid), 221-229. Furrer J, Dropsch H., Stohi J. (1998) "Catalyst Development for the Destruction of Volatile Organic Conqiounds in the Flue Gas of Municipal Waste Incinerators". In Proceed, of 1T3 Conference held in Salt Lake City, UT, USA, 337-340. (Ed. by Univ. of California at Irvine). 

Shiraishi Y., Kawabata H., Chichibu S., Furuta S. (1995) Total Flue Gas Treatment System of Municipal Solid Waste Incineration Plant . Kobelco Techn. Review, no. 18,46-49. 

Poisoning of De NO SCR Calalyst by Flue Gases from a Waste Incineration Plant... 

POISONING OF DE-NOx SCR CATALYST BY FLUE GASES FROM A WASTE INCINERATION PLANT... 

So far, most of the attention has been paid to reducing the NOx emissions from flue gases emanating from burners and boilers which use coal, oil and natural gas as fuel. Municipal waste incinerators are usually located within the big city areas and as such, special measures are expected to be taken in order to reduce their various emissions. 

Up to now a lot of attention has been paid to improving the performance of SCR catalysts with respect to making them more resistant to the poisonous compounds present in the flue gases, mainly SOx and As, which are results of burning with coal, oil and gas (ref. 5 and 6). At the same time relatively little information has been presented on the poisoning effect of flue gases from municipal waste incinerators, on the SCR-type de-NOx catalysts. 

The aim of this paper is to study the effect of the emissions from burning wastes, I.e, from municipal waste incinerators, on the SCR-type catalyst, specially when the catalyst is placed at the tail-end of the process, i.e. after the de-SOx unit. By choosing the tail-end position, most of the emissions harmful to the de-NOx catalyst, are absorbed either by the dust separator or during the de-SOx stage. Nevertheless about SO ppm SOx still present in flue gases. It is well known that at temperatures of below 250 C the ammonia sulphates are formed where SOx is present in the flue gases. 

Ageing of the de-NOw catalyst in the stream of flue gases from a municipal waste incinerator... 

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