Hazardous or toxic waste destruction or containment – Containment – Solidification – vitrification – or cementation
Patent
1998-01-12
2000-10-17
Dunn, Tom
Hazardous or toxic waste destruction or containment
Containment
Solidification, vitrification, or cementation
110234, 110243, 110244, 110245, 110255, 422139, 422141, 422142, 422143, 422145, 422146, 423DIG18, 588208, 588213, 588214, 588215, 588216, 588217, 588226, 588900, A62D 300, B01J 818, B09B 300, F23B 700, F23G 500, F27B 1500, F27B 1508, F27B 1514
Patent
active
061334995
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention concerns a superheated steam generator which employs incinerating municipal garbage or industrial waste, and produces superheated steam with the heat energy from such an incineration. The superheated steam produced by this apparatus might, for example, be used for an electric power plant. The heat energy of the incineration can also be used to melt the ash resulting from incineration so that it can be used again as a resource.
TECHNICAL BACKGROUND
In the prior art, apparatuses to incinerate waste such as municipal garbage have frequently employed fluidized beds. Such apparatuses blow air or the exhaust gas from incineration into the fluidized bed medium, which may be sand, from below a dispersion plate (e.g., a perforated plate) in the furnace onto which the sand is supplied. The material is heated and thereby fluidized. Waste such as municipal garbage is fed into the fluidized bed formed in this way and combusted.
The gases generated by this incineration are exhausted through a discharge line and enter a boiler. In the boiler, steam is produced through thermal contact with heated water.
The steam is used as the drive source for a turbine in an electrical plant.
Organic compounds such as vinyl chloride plastics are a component of waste material such as municipal garbage. The combustible portion contains approximately 0.2-0.5% Cl. When combusted, chlorides contained in the vinyl chloride plastics mixed in with waste material such as municipal garbage are converted to HCl. (Normally, the HCl content of the exhaust gas from the incineration of garbage is in the range of 500-1,000 ppm.) This HCl acts on the tubes in the boiler used to produce steam which is placed at the exit of the incinerator and corrodes them. At temperatures above 350.degree. C., as the surface temperature of the tubes increases, the corrosion becomes extremely serious.
It was thus necessary in prior art incinerators to keep the temperature of the tube surfaces below 350.degree. C. This limited the temperature of the steam which could be produced to approximately 300.degree. C. As a result, the generating efficiency of prior art garbage incinerators was below 15%. In contrast, fuels such as heavy oil or LNG (liquified natural gas) are virtually free of chlorine compounds. Boiler tubes in plants which burn these fuels can withstand temperatures of 500-600.degree. C., yielding an efficiency of 40%. Because of their poor efficiency, there has been a strong demand for the improvement of waste incinerators.
DISCLOSURE OF THE INVENTION
This invention was developed in consideration of these technical problems. The object of this invention is to provide a method and an apparatus to efficiently produce superheated steam at high temperatures and under high pressure without the corrosion of the boiler tubes caused by chlorine compounds.
Another object of this invention to provide a method and an apparatus to produce superheated steam which can efficiently reduce the chlorine and produce superheated steam at high temperatures without using an expensive, high-quality substance for the boiler tubes.
Another object of this invention is to provide a method and an apparatus to produce superheated steam which could efficiently combust char and pyrolyze it in apparatuses for those purposes, and which can efficiently reduce the chlorine and produce superheated steam at high temperatures.
Yet another object of this invention is to provide a method and an apparatus to produce superheated steam which can efficiently combust mixtures containing char.
Yet another object of this invention is to provide a method and an apparatus to produce superheated steam which can efficiently pyrolyze char in a char pyrolyzing device, prevent tars from adhering to the pipes, prevent coking, and reduce the quantity of dioxins and NOx released, while efficiently reducing the chlorine and producing superheated steam at high temperatures.
Yet another object of this invention is to provide a method and an apparatus to produce superheated steam whi
REFERENCES:
patent: 5327726 (1994-07-01), Damna et al.
Robert H. Perry and Cecil H. Chilton. Chemical Engineers' Handbook. Fifth Edition McGraw Hill Book Company. p. 20-77, 1973.
Horizoe Hirotoshi
Kaihara Yuji
Kawami Yoshimasa
Sato Jun
Shimizu Yoshihito
Dunn Tom
Medina Maribel
Mitsubishi Heavy Industries Ltd.
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