Furnaces – With exhaust gas treatment means
Patent
1997-01-30
1998-05-05
Lazarus, Ira S.
Furnaces
With exhaust gas treatment means
110216, 110204, 110210, F23J 1500
Patent
active
057461414
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process of waste incineration with acid gases and particulate removal upstream the thermal recovery section for production of electric and/or mechanical energy, and moreover it relates to an incinerator used for this process.
BACKGROUND ART
It is known that the flue gases resulting from the present waste disposal processes involving thermal treatment are characterized by high values of acid and particulate content.
In detail, the content of hydrochloric acid in the gas phase and of chlorides in the particulate is high in municipal solid wastes (MSW), in hospital solid wastes incineration and in special waste incineration, according to the chlorine content of the material subjected to thermal treatment.
This implies, in the current incineration processes with heat recovery from flue gases before their discharge to the atmosphere, serious design and operating difficulties for the plants due to corrosion, especially with regard to the boiler's metallic heat transfer surfaces and to the different structural and connecting parts. As a result, in the above mentioned plants the investment cost rises, if special materials are used, or, on the other hand, an increase in operating costs ensues, due to frequent shut down operations and repair of the damaged parts, or, more usually, both situations occur.
Furthermore, the above mentioned corrosion phenomena occur more rapidly the higher the temperature of the metallic heat transfer surfaces.
The steam produced by heat recovery can be expanded in a turboalternator device, and the efficiency of the operation increases with steam temperature and pressure. In practice, in order to reduce corrosion phenomena, it is necessary to limit the superheating temperature of the steam to rather low values (usually between 320.degree. and 380.degree. C.), whereas in high efficiency thermal power plants, operated with conventional fuels, the superheating temperature of the steam is usually in the range between 450.degree. C. and 540.degree. C.
Therefore a compromise solution is usually adopted taking into account the opposite requirements of corrosion phenomena reduction and of turboalternator efficiency increase. This compromise limits the performance and service availability of the incinerators operating nowadays.
Another aspect to be considered is that concerning the environmental effects due to waste incineration plants. The discharge of flue gases from incineration plants is subjected to rules (indicated by European Community directions or imposed by national or local Authorities) which set the maximum allowable content of pollutants or micro-pollutants. In Table 1 the limits in force nowadays for some of them are shown:
TABLE 1 ______________________________________
EEC ITALY (*)
______________________________________
PCDDs + PCDFs
______________________________________
(*) (existing plants)
Among these substances, dangerous micropollutants, such as organic chlorinated substances, like dioxins and furans (PCDDs and PCDFs) are produced by the synthesis "de novo" according to Stieglitz and Vogg, (Chemosphere Vol. 16 N. 8/9 1987) in the cooling of flue gases generated by waste incineration. This synthesis can occur on the heat exchange surfaces of the boiler starting from soot or from other constituents of flying ashes and from HCl or others chlorine compounds.
In order to comply with these restrictive rules whose purpose is the environmental protection, according to some known incineration processes the reduction of acid gases is accomplished by the reaction of the flue gases with an alkaline reagent, by means of the well known dry, semi-dry or wet processes, downstream the flue gases cooling section. These process cannot avoid the high temperature corrosion phenomena on the boiler heat transfer surfaces. As an example the paper of K. T. Fellows and M. J. Pilat (J. Air Waste Manage. Assoc.; Vol. 40 No. 6, 1990) deals with the use of sodium bicarbonate at low temperature, near 200.degree. C., in order to absorb hy
REFERENCES:
patent: 3722433 (1973-03-01), Kramer
patent: 4091747 (1978-05-01), Chase
patent: 4284015 (1981-08-01), Dickinson
patent: 4355601 (1982-10-01), Hattiangadi
patent: 4376373 (1983-03-01), Weber et al.
patent: 4590868 (1986-05-01), Ishihara
patent: 4620492 (1986-11-01), Vogg et al.
patent: 4860670 (1989-08-01), Jorgensen
patent: 4958578 (1990-09-01), Houser
patent: 5241916 (1993-09-01), Martin
patent: 5345884 (1994-09-01), Vandycke et al.
patent: 5425316 (1995-06-01), Malone
patent: 5553555 (1996-09-01), Gosselin, Jr. et al.
patent: 5632211 (1997-05-01), Okuno et al.
Lacquaniti Luigi
Liuzzo Giuseppe
Palitto Marcello
Verdone Nicola
Consorzio Obbligatorio Nazionale Per Il Riciclaggio Dei Contenit
Lam Nhat-Hang H.
Lazarus Ira S.
LandOfFree
High temperature acid gases and particulate removal in waste inc does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with High temperature acid gases and particulate removal in waste inc, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High temperature acid gases and particulate removal in waste inc will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-45513