Furnaces – Including means to feed solid fuel – Movable grate
Patent
1989-08-01
1991-07-23
Bennett, Henry A.
Furnaces
Including means to feed solid fuel
Movable grate
110291, F23H 708
Patent
active
050333968
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a grill arrangement, particularly for stepped pivoting grills, comprising feeding means, possibly drying and firing grills and at least one vertical grill with associated horizontal grill as well as following burnout grill.
Such stepped pivoting grills have proved themselves very well in practice. It is already known (P 28 33 255.0) to provide such stepped pivoting grills, the individual steps of which each consist of a horizontal and a vertical grill, with air-cooled grill bars, the air being introduced for example centrally in the grill bar, distributed to both sides via passages beneath the grill bar upper side and the air being discharged into an air distributing box which is located beneath the horizontal and vertical grill, from whence it enters the combustion chamber via the slots between the grill bars along the flanks of the latter and the masonry.
The intention is now to further develop this extremely advantageous construction so that the combustion performance is increased and intensified and the combustion process optimized and the firing-dependent pollutants, for example NO.sub.x, CO, C.sub.total and the production of hydrocarbon C.sub.n H.sub.m are minimized.
This is surprisingly achieved according to the invention in a grill arrangement of the type mentioned at the beginning by at least one swirling or vortex component step in the stepped pivoting grill.
Preferably, the swirling component steps are so constructed that at least some grill bars have blowout or discharge openings for air. It is favourable for high velocity nozzles to blow out perpendicularly to the horizontal grill plane.
The aforementioned problem is thus completely solved by the step according to the invention, i.e. the combustion performance is considerably increased and intensified, the combustion process optimized and the firing-dependent pollutants such as for example NO.sub.x, CO, C.sub.total and hydrocarbon C.sub.n H.sub.m are minimized.
Via the so-called vortex or swirling components (swirling step in the frame of a stepped grating) absorption agents such as lime may also be added, thereby bonding pollutants.
In addition, a surface area increase of the fuels is obtained by abrasion in the fluidizing zone; the combustion process is thereby favourably influenced. This takes place in particular on addition of centrifuged sewage sludge including dry substances of about 30% to the refuse and burning the refuse and sewage sludge together.
In the region of the pivoting grill elements equipped with so-called swirling or vortex components a quasi fluidized bed is formed through which the fuel must pass along its path.
The transport of the fuel and the transport of the fuel residues and their distribution takes place in the usual manner as employed on any grill system, in particular stepped grill system.
Thus, the good properties of a grill and fluidized bed firing are combined by such a system.
The resulting fluidized bed additionally provides a fuel transport or residue transport. The residues are finally discharged via a deslagging system of known type.
In a further development of the invention the swirling nozzles are to be still better protected, the grill arrangement kept still cleaner and the temperature resistance still further increased as far as possible.
Preferably, for this purpose the grill bars of the horizontal grill arrangement comprise a slag-repellant ceramic covering of high temperature resistance embedding the swirling nozzles. This can also be done at least in the lower portion of the vertical grills.
Preferably, the ceramic covering consists of slag-repellant silicon carbide which for example can be stamped on. The ceramic material itself thus has an additional holding by the swirling nozzles. The arrangement of horizontal grills with distributors and such grills is suitable in particular for special refuse such as hospital or chemistry waste which are partially introduced in bundles with liquid content or become pasty or liquid in the burning off phase. The grill construction here
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patent: 4600098 (1986-07-01), Orren
patent: 4671190 (1987-06-01), Moreau
patent: 4732561 (1988-03-01), Eiring et al.
Bennett Henry A.
Gromada Denise L. F.
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