Furnaces – Refuse incinerator – Refuse suspended in or supported by a fluid medium
Patent
1985-08-22
1987-03-03
Favors, Edward G.
Furnaces
Refuse incinerator
Refuse suspended in or supported by a fluid medium
110263, 110347, 431170, F23G 500, F23G 700
Patent
active
046466614
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an industrial furnace for the combustion of solid, liquid, pasty, or gaseous fuel, with the furnace having a fuel inlet, and gas and ash outlet means. The present invention also relates to a method of producing a combustible fuel, which is rich in energy and low in noxious material, by treating household refuse, and/or industrial refuse which is similar to household refuse, with size-reduction, screening, and withdrawal apparatus, including magnet screens, for the selective recovering of various refuse constituents, especially paper.
DESCRIPTION OF THE ART
With regard to the industrial furnace as the subject matter of the present invention, the most economical and environmentally-favorable solution of the various furnace systems in the state of the art has proven to be the fluidized bed furnace, which is especially used for the combustion of complicated refuse, and fulfills in particular the environmental requirements to the extent that significantly lower quantities of noxious materials are emitted than with conventional furnaces.
With fluidized bed furnaces, the combustion air is conveyed through a combustion chamber bottom which is equipped with air nozzles. Located on this bottom is a layer comprised of fine-grained inert material. The layer is swirled by the air stream which is conveyed through from below, whereby for the initiation of the combustion process the layer is heated to the ignition temperature of the respective fuel. For this purpose, a starter burner operated with oil or gas is generally used.
Immersion heating surfaces are frequently placed in the fluidized bed, and assume the task of cooling the fluidized bed to the desired combustion temperature.
After the ignition temperature has been achieved, the respective fuel is introduced into the fluidized bed. During combustion of the respective fuel, the granule size is continuously being reduced, so that the individual fuel particles become lighter, until the remaining ash particles are picked up by the rising gas stream and are carried off.
However, the heretofore known fluidized bed furnace has critical drawbacks. On the one hand, due to the circulating fine sand, nearly all of the inner surfaces of the respective combustion chamber have erosion problems due to the so-called "sandblast effect". Considerable wear occurs especially on the immersion heating surfaces and on the lining of the combustion chamber, as a result of which the likelihood of repair for the overall combustion unit is negatively impacted. Furthermore, the degree of combustion of the respective fuel is frequently insufficient, so that considerable effort must be undertaken with regard to cleaning the flue gas. Since in addition to the use of generally conventional fuels, fuel produced from household refuse and/or industrial refuse which is similar to household refuse is also supposed to be used in such furnaces utilizing fluidized beds, there exists the further problem of making available combustible fuel which is rich in energy and low in noxious materials, and is produced from such refuse. Methods for preparing household refuse and/or industrial refuse which is similar to household refuse are known, for example, from U.S. Pat. No. 4,187,775 and German Offenlegungsschrift No. 30 37 714.
With regard to the production of fuel from refuse, German Pat. No. 31 28 560 discloses a method for treating the combustible fraction of size-reduced household refuse for producing so-called fuel pellets in a briquette press; this fraction has been freed of dense-medium material, and to the extent possible has been dried to a residual moisture content of 8 to 10%. In this manner, it is possible, without adding binders, to produce briquettes which have a relatively high heating value, and are stable during transport and storage.
However, for the following reasons the production of pellets will be of secondary importance for future furnace concepts: mechanical expenditure and energy requirements for the compacting of the pellets in
REFERENCES:
patent: 3939782 (1976-02-01), Albrecht
patent: 4258005 (1981-03-01), Ito et al.
patent: 4505230 (1985-03-01), Caplin
patent: 4546709 (1985-10-01), Astrom
Flender Hans F.
Roos Johann
Favors Edward G.
Roos Udo
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