Furnaces – Refuse incinerator – Refuse suspended in or supported by a fluid medium
Patent
1997-01-29
1999-09-21
Lazarus, Ira S.
Furnaces
Refuse incinerator
Refuse suspended in or supported by a fluid medium
110204, 110210, 110214, 110216, 110251, 110255, 431170, 16510416, F23G 500, F23B 500, F23B 502, F23J 300
Patent
active
059540010
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the heat treatment of waste. By heat treatment is meant not only the destruction of the waste but also deriving economic benefit through recovery of the greater part of its energy content.
BACKGROUND OF THE INVENTION
One way to treat waste is to carry out heat treatment on it to convert it into an inert material of reduced volume compared to its original volume, during which treatment, the waste gives up a great part of its energy content in the form of heat energy exchanged with an energy recovery unit, for example.
DESCRIPTION OF RELATED ART
A problem that is frequently encountered in the treatment of waste is the necessity to sort it beforehand, to separate the combustible materials from the other materials and to break the latter waste down into very small fragments to facilitate the treatment. The prior art grid type devices cannot always treat any type of waste, and in particular they offer only a limited possibility of treating sludge from settling tanks of waste water purification installations.
One major problem encountered in the treatment of waste is the presence in the waste of substances which release chlorine when decomposed by heat, the chlorine very quickly causing corrosion damage of the heat exchanger tubes of the energy recovery unit heaters.
SUMMARY OF THE PRESENT INVENTION
One aim of the present invention is to define a reactor able to receive all types of waste, including settling tank sludge, requiring no preliminary sorting and requiring only coarse chopping of the waste.
Another aim of the present invention is to define a reactor in which the heat exchange area, for example the area of heat exchange with the heat exchanger tubes of the superheaters of an energy recovery unit, is free of chlorine.
These aims are achieved in a fluidized bed reactor derived from that described in U.S. Pat. Nos. 5,508,007 and 5,316,736, and its continuation U.S. Pat. No. 5,453,251 and hereby incorporated by way of reference into the present application.
The invention consists in a fluidized bed reactor for heat treatment of waste and heat exchange between recirculating solids and a heat exchanger unit, such as a steam generator and/or a superheater, the reactor being of the type including an axial recirculating fluidized bed and at least first and second lateral dense fluidized beds respectively along a first wall and a second wall of the jacket of the reactor, characterized in that the waste is fed via at least one point on said first wall above the first lateral dense fluidized bed, the reactor further comprising at least one duct for extracting non-fluidizable heavy elements at the base of the first fluidized bed.
The heat exchange is preferably effected in the second lateral dense fluidized bed.
The duct for extracting the heavy elements has an inclined part extending an inclined hearth of the first lateral dense fluidized bed, and air blower nozzles directing a variable direction flow being flush with the surface of said hearth.
The extraction duct is provided with adjustable air injector means for varying the flowrate of the solids in the duct.
The base of the second dense fluidized bed is connected by at least one extractor duct to the base of the recirculating fluidized bed.
The extractor duct is provided with adjustable air injector means for varying the flowrate of the solids in the duct.
The recirculating fluidized bed and the first dense lateral fluidized bed are fluidized by a mixture of primary air and recycled smoke.
The second dense lateral fluidized bed is fluidized by a mixture of air and dechlorinated recycled smoke.
Tertiary air is fed through each of the reactor walls by variable flowrate injector means at a height above that of the points at which the waste is introduced.
At least the tertiary air injected into the wall at which is located the heat exchange dense fluidized bed is mixed with recycled and dechlorinated smoke.
The base of the reactor includes means for extracting inert material.
The duct for extracting non-fluidizable heavy e
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patent: 5316736 (1994-05-01), Vidal et al.
patent: 5325823 (1994-07-01), Garcia-Mallol
patent: 5453251 (1995-09-01), Vidal et al.
patent: 5505907 (1996-04-01), Hiltunen et al.
patent: 5508007 (1996-04-01), Vidal et al.
Ciric Ljiljana V.
GEC Alsthom Stein Industrie
Lazarus Ira S.
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