CA1187359A

CA1187359A - Burner for maple sap evaporator

Info

Publication number: CA1187359A
Application number: CA000433919A
Authority: CA
Inventors: Leopold Bosse
Original assignee: LES EVAPORATEURS WATERLOO Inc
Current assignee: 3870073 CANADA Inc
Priority date: 1983-08-04
Filing date: 1983-08-04
Publication date: 1985-05-21

Abstract

ABSTRACT OF THE DISCLOSURE

A wood burner for a maple sap evaporator including a power-operated fan for forcing combustion air through the combustion chamber. A shutter adjusts the air pressure. More uniform heat distribution is obtained under the evaporator vats.

Description

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FIELD OF THE INVENTION
The present invention relates to a wood-burning heater which operates satisfactorily in a maple sap evaporator.
BACKGROUND OF TIIE INVENTION
To produce maple syrup the usual practice is to boil the sap in large vats until the syrup has been reduced by evaporatLng to the desired consistency.
An ever-increasing number of people sre converting their oil-burning systems to wood-burning due to the high cost of energy, but very little technical advance seems to have been made in this art. With the conventional wood-burning aystem, it is hard to get a uniform flow of heat all along the vats and with the use of a flat grille separating the fire pot and ash pit.
A lot of clogging occurs due to the accumulation of ashes, thus restricting the flow of air in the fire pot.
OBJECTS OF THE INVENTION
.... .. _ _ It is the general object of the present invention to use new technology to update the old design of the wood-burning system in a maple sap evaporator.
It is a more specific object of the present invention to provide a wood burner which produces more heat for the same quantity of fuel by the provision of a fan forcing the air in the combustion room to provide a greater quantity of oxygen in the system, thus allowing a better control of the combustion and also permitting a better distribution of the heat along the vatY sur~ace.
Another object is to provide a heat source that will need the minimum oi maintenance, a special grille having been designed to prevent the clogging of the air passages due to the accumulation of ashes; the better circulation of the air due to the new grille also improves the combustion and so the effi-ciency of the burner.

BRIEF DESCRIPTION OF THE DRAWINGS
The -invention will be further described, by way of example, with reference to the accompanyLng drawings, in which

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Figure 1 i8 a side elevation, partlally in section, of the complete burner assembly 8howing i~s ingtalla~ion under a maple sap evaporator:
Figure 2 is a cross-sectional vlew on line 2-2 of Figure 1.
Figure 3 i9 a fragmentary view o Figure 2 showing the construction of the grilles on an enlarged scale; and Figure 4 i9 a perspective view of the burner assembly complete with the air blower.
DETAILED DESCRIPTION OF THE INVENTION
Rbferring to the drawings, ~igure 1 illustrates the invention applied to a conventional maple sap evaporator comprislng an elongated pan la holding a number of vats 1 and located~ over a fire box 2, which may have a length of, say, 20 feet and a flue (not ~ho~n? at the shallow rear end portion of box 2. Wood logs 3 are stoked for combustion through an opening in ~he front end portion 2a of fire box 2 closed by a door 4.
The fire box 2 i9 of substantially the ~ame width and length as the pan la but the front end portion 2a of fire box 2 has a length which i9 only a fraction of the total length of fire box 2.
Thi8 fire box 2 is dQsigned ~o provide- heat along the entire length of the vats 1, but in conventional arrangements, uslng wood logs as fuel, this heat i9 not uniform, resulting in overheating of the vats 1 closest to fire box end portion 20.
~ he heat source al80 comprises an ash pit 6 located under and substantially co extensive with the fire box end po~tion 2a. An undulated grille 7 forms the bottom of fire box end portion 2a and separates the latter from the ash pit 6. The grille 7, the furrows of which are oriented in the longitudinal axis, is reinforced along each crest by a metal plate 8 fixed at each extremity to the edges of grille 7.
The undulated grille 7 comprises a number of holes 9 to allow the passage of the air from the ash plt 6 to the ftre box 2 and the passage of the ashes falling in the ash pit 6. The access to the inside of the ash pit 6 for cleaning is done by means of a number of cleaning doors 10 located on the same side a~ the fire box doors 4.

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The air i9 forced into the a8h pit 6 and fire box 2 by means of a centrifugal fan 11 powered by an electric motor 12. The alr is entering the a~h pit 6 through an opening 13a made in an upright wall 6a of ash pLt 6, said wall 6a extending below and facing the bottom wall 26 of fire box 2. The air i8 carried from the fan 11 to the ash pit 6 by means of cluct 13 of rectangular cross-section. The duct 13 comprises a mechanical shutter 14 to control the alr pressure inslde the flre box 2.
The pressure must be regul~ted 30 i'C is sufficient to provide a uniform flow of heat on the vats 1 under surface but not too high so it 10 creates a pressure differential inside the burner and throw ashes or smoke in the room, especialLy when the doors 4 are opened to put wood 3 in the fire box 2.
The inside walls of the fire box 2 are covered with a refractory material 15 to assure a better heat insulation to improve the efficiency and as a security means a8ainst fire., 11~e ash pit 6 is supported by at least four adju3table legs 16 to assure a perfect fit between the ash pit 6 and the under3ide of fire box end portion 2a.
This invention is advantageous in that it gives a better combustion 20 of a fuel, such as wood, because of the forced air but does not required to seal the fire box 2 and the ash pit 6, since the alr pressure 13 not too high.
Another advantage i8 the undulated grllle 7 that does not get clogged because of air accumulatlon of ashe3 arld 90 allow0 the air 10 to pass through more éfficiently.
It will be understood that other modlfications withln the scope of the appended claims may be rnade in the deslgn and arrangement of the parts without departing from the splrlt of ~he Lnventlon.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED, ARE DEFINED AS FOLLOWS:

1. A maple sap evaporator comprising, in combination, an elongated, rectangular pan holding a series of evaporating vats, an elongated fire box located under and covering the entire width and length of said pan and adapted to communicate with a chimney at one end portion of said fire box, a grille forming the bottom of the opposite end portion of said fire box, said grille extending lengthwise along a small fraction of the total length of said fire box, said fire box progressively decreas-ing in height from said grille to said one end portion, and having a bottom wall which is spaced above a surface supporting said evaporator, an ash pit located under and co-extensive with said grille, access openings for said fire box and said ash pit closable by door for stoking wood logs onto said grille and for ash removal under said grille, respectively, said ash pit having an upright wall extending below and facing said bottom wall of said fire box, a duct having one end communicating with said ash pit through said wall, a power-operated air fan connected to the other end of said duct and an adjustable damper in said duct intermediate said fan and said ash pit to regulate the flow of air forced into said ash pit by said fan, said forced flow of air causing substantially uniform heating, by the burning wood logs resting on said grille, of substantially the entire surface of said pan exposed to said fire box, said grille having a number of undulations which extend longitudinally of said fire box and said undulations having a plurality of holes.