Furnaces – Refuse incinerator – Refuse suspended in or supported by a fluid medium
Patent
1984-03-22
1985-08-20
Yuen, Henry C.
Furnaces
Refuse incinerator
Refuse suspended in or supported by a fluid medium
122 4D, F22B 102, F23G 500
Patent
active
045357064
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a fluidised bed combustion apparatus and to furnaces and/or incinerators embodying such apparatus. The invention is particularly concerned with the improvement of combustion in such fluidised bed apparatus, particularly combustion of waste material of either high or low calorific value and other high or low grade fuels; either with the object of waste disposal, or for the generation of heat for some useful purpose, or for a combination of those objects.
It has been proposed to provide fluidised bed combustion apparatus in which a fluidised bed of granular material is supported in a housing or a combustion chamber on an air diffuser bed support.
In such an arrangement fuel or waste material to be burned either to raise heat or for disposal purposes, is fed into the fluidised bed to be burned therein. The oxygen for such combustion comes at least in part, and usually entirely, from air fed into the bed from the diffuser support to fluidise the bed. The bed of granular material is usually sand or other refractory material and may comprise in part, or even totally, granular ash residue from previous combustion.
The diffuser in some cases is arranged to slope from one side of the bed to an opposite side, and it has been proposed that the supply of fluidising air to various areas of the diffuser should be selectively controlled to fluidise the bed material to a varying degree above those areas so that circulation of the bed material about a transverse horizontal axis is caused.
It is an object of the present invention to provide an arrangement of such a fluidised bed which gives improved combustion conditions.
Accordingly the present invention provides a fluidised bed combustor in which material may be burned in a combustion zone of a fluidised bed and the material of such fluidised bed may be caused to circulate from the combustion zone across and over an upper region of the bed from one side of the bed, down through a feed zone of the bed, into which feed zone material to be burned may be fed and mixed with the material of the bed, and then through an ash segregation zone of the bed back into the combustion zone of the bed.
Preferably a baffle having vertical extent is provided in the fluidised bed to separate the feed zone from the combustion zone.
Preferably the air diffuser bed support provided in the combustor for the fluidised bed is divided into discrete portions and means is provided for selectively controlling the air flow from those portions into the bed so as to promote such circulation.
Preferably the air diffuser portion below said one of the bed is arranged to fluidise the bed on that one side vigorously so as to provide means for driving such circulation.
Preferably the supply of air to the bed is arranged so that bed material circulates from said ash segregation zone directly through the combustion zone and on to the top of the feed zone.
Preferably means is provided to control the air flow to the combustion zone separately.
Preferably means is provided to control the air flow to the ash segregation zone separately.
Preferably a gap is provided in the air diffuser between the portions associated with the ash segregation zone and the combustion zone to form a trough for the extraction of ash resulting from combustion.
Preferably the bottom of such trough is provided with an air diffuser to fluidise the bed material therein.
Preferably means is provided to control the supply of air to the feed zone separately.
Preferably a baffle is provided above the fluidised bed extending from said one side at least partially across the bed towards said other side.
Preferably a secondary air diffuser is provided in the bed above the ash segregation zone in the fluidised bed extending at least over the ash trough.
Preferably heat exchange means is provided to lie just within the surface of the bed in operation thereof, whereby heat may be extracted from the bed.
Preferably the ash trough is connected to a conduit leading to the bottom of a vertical conduit so that bed material and ash m
REFERENCES:
patent: 3397657 (1968-08-01), Tada
patent: 3745940 (1973-07-01), Hibbert
patent: 4227488 (1980-10-01), Stewart et al.
patent: 4270468 (1981-06-01), Robinson et al.
patent: 4323037 (1982-04-01), Meyer-Kohrweg
patent: 4330502 (1982-05-01), Engstrom
patent: 4335662 (1982-06-01), Jones
patent: 4349969 (1982-09-01), Stewart et al.
patent: 4363292 (1982-12-01), Engstrom
patent: 4377119 (1983-03-01), Noack
Sodic Societe Anonyme
Yuen Henry C.
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