Furnaces – Including means to feed solid fuel – Movable grate
Patent
1988-12-20
1990-02-20
Favors, Edward G.
Furnaces
Including means to feed solid fuel
Movable grate
110291, 110298, 198773, 414156, F23H 708
Patent
active
049016539
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a furnace hearth equipped with a grate designed to support a burning mass of solid fragments, notably urban waste, and comprising, sloping downwardly between a loading area at the upstream end and an ash box at the downstream end, at least one bed made up of a succession of transverse bars with a dorsal surface for supporting the mass and a frontal surface with a lower edge sliding of the dorsal surface of the immediately upstream bar, the bars being attached by a downstream end alternately to a fixed frame of the hearth and a mobile frame that can be reciprocated longitudinally by control means, the hearth further comprising, under the grate, at least one draft chamber equipped with ventilation means for feeding combustion-supporting air to the mass through draft holes provided in the bars and, above the grate, a furnace chamber connected to a fumes extractor flue which extends longitudinally from the loading area to a vertical wall referred to as the altar wall, the hearth being extended by a sprung roof from the altar wall to the ash box.
The type of grate fitted to these hearths, in which the surfaces of the elements exposed to the thrust of the burning mass fragments face upstream to oppose rapid descent of the combustible solids and to cause mixing or poking of the mass, has been extensively described in the state of the art since patent U.S. Pat. No. 2,250,067 filed in 1938. Since then improvements have been made, directed notably to the arrangement of draft holes which pass through the bar elements to supply combustion-supporting air to the burning mass from draft chambers situated beneath the grate.
Arrangements have been proposed for improving the poking action by providing at least some of the bar elements with projections where their dorsal and front surfaces meet and for improving the cooling of the bars by the draft of combustion-supporting air.
Patent document FR-A-No. 2 574 160 describes a furnace hearth which comprises bar elements provided with faceted transverse projections at the junction of the front surface and the dorsal surface and on the latter surface, with draft holes provided in a rear facet of the projections so as to face downstream and to direct jets of air from below the grate into the mass of combustible solids in a direction at approximately 15.degree. above the horizontal.
This patent document further describes means for maintaining the adjoining bar elements in alignment.
Problems with adjusting the combustion cycle arise from the use of combustible materials comprising solid fragments of varying quality, such as urban waste, sometimes with relatively high concentrations of incombustible components that will form clinker and ash.
What is more, most solid combustible materials exhibit two combustion modes in succession, the first of which is a carbonization mode in which volatile components which burn are released to produce long flames and a brasier mode, virtually without flames, in which combustion continues on the solid components of the combustible material (the "live coals").
The optimum combustion conditions differ according to the combustion mode. During carbonization the bed of combustible material may be relatively thick and the head loss of the combustion-supporting air through the bed remains moderate, the passages between combustible fragments being of relatively large cross-section and the formation of flames encouraging the draft of combustion-supporting air. In brasier mode however, the ash and clinker produce significant head losses in the combustion-supporting air and it is advantageous if the beds are less thick. Also, heat is transferred from the ignited parts to the remaining combustible parts mostly by radiation and to some degree by convection of fumes, and this transfer is compromized by the presence of the ash and clinker.
If, as is common practise, the combustion conditions are adjusted to achieve a compromise between optimizing the carbonization mode combustion and optimizing the brasier mode combustion, approximating th
REFERENCES:
patent: 2250067 (1941-07-01), Martin
patent: 3413938 (1968-12-01), Dvirka
patent: 4320710 (1982-03-01), Steiner et al.
Brown Charles A.
Brown Charles E.
Favors Edward G.
T.I.R.U. - Traitement Industriel des Residus Urbains
LandOfFree
Hearth for a furnace, notably a furnace for urban waste, includi does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hearth for a furnace, notably a furnace for urban waste, includi, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hearth for a furnace, notably a furnace for urban waste, includi will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1608576