Furnaces – Including fluid fuel burner – Powdered solid fuel
Patent
1995-07-27
1997-10-28
Bennett, Henry A.
Furnaces
Including fluid fuel burner
Powdered solid fuel
110264, 110265, 110104B, 431187, F23C 110
Patent
active
056808224
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a burner for solid fuel, e.g. in the form of pellets, and is intended for mounting on a boiler furnace, the forward portion of the burner being insertable through an opening in the furnace casing such as to extend into the combustion zone of the furnace.
2. Description of the Related Art
During recent years the use of different alternatives to oil firing has become more and more usual, especially for heating dwellings. In such cases, wood chips or other solid fuel have come into use, a suitable arrangement being adopted to feed the fuel to the combustion zone in the furnace. In order to avoid a costly and laborious installation, new types of burner have been developed for these alternative fuels, and these burners can complement an existing oil burner, or be mounted on the furnace in its stead.
A problem with the new varieties of burners is obtaining a regulated, continuous and disturbance-free feed of the solid fuel to the combustion zone of the furnace, without unnecessary breakdown in operation, as well as complete combustion of the fuel.
SUMMARY OF THE INVENTION
The object of the present invention is to achieve a burner of the kind mentioned above, where the mentioned problems have been eliminated, while at the same time it is simple in construction and cheap to produce. The distinguishing features of the invention are disclosed in the accompanying claims.
Due to the inventive burner there is now obtained very reliable, disturbance-free and continuous feeding of the solid fuel towards the combustion zone in the furnace. Since there is a very effective mixture of primary combustion air and fuel, the air being blown towards the combustion zone, and since this is in combination with slow rotation of the burner ignition chamber, very effective combustion is obtained for the furnace. Secondary air is fed to the forward part of the ignition chamber, and in this way the temperature inside the chamber can be controlled by balancing the primary air with the secondary air, while rotation of the chamber prevents ash from collecting in it. So as to further eliminate any build-up of ash in the chamber, it may be provided with a plurality of helically formed ridges or fins extending towards its opening. The use of a separate feed means that freely deposits the fuel at the inlet of a feed screw included in the burner ensures that back-firing is prevented, which could occur should there be operational stoppages or disturbances.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail, with the aid of some embodiment examples, and with reference to the accompanying drawings, where:
FIG. 1 is a schematic cross-section in elevation of a solid fuel burner in accordance with the invention, where it is mounted on a boiler furnace.
FIG. 2 illustrates an alternative embodiment example of the forward part of the feed screw implemented as a cone, with holes for the passage of primary air.
FIG. 3 illustrates an alternative embodiment of an ignition chamber, and
FIG. 4 is a schematic cross-section in elevation of another alternative embodiment of the inventive burner.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1 there is illustrated a preferred embodiment of a solid fuel burner 2, preferably for pellets. The burner is mounted instead of an oil burning unit on a boiler furnace 1. The forward portion 3 of the burner 2 is inserted in an opening 4 in the casing 5 and extends into the combustion zone 6 of the furnace 1. To advantage, the fuel may be pellets, which may comprise timber waste such as bark, sawdust and the like.
The burner 2 includes a tubular body 7, through which extends a feed screw 8 for feeding the fuel through the body. The free end 9 of the screw 8 terminates in the forward portion 3 of the burner 2, and the opposite, closed end 10 of the screw 8 is rotatably carried by a bearing 11. Rotation of the screw 8 is enabled via a drive means 12 by a motor situated in a housing 13 fix
REFERENCES:
patent: 1726870 (1929-09-01), Trent
patent: 1769197 (1930-07-01), Wetmore
patent: 1945850 (1934-02-01), Filmer
patent: 2932712 (1960-04-01), Levin
patent: 4096808 (1978-06-01), Trickel
patent: 4803836 (1989-02-01), Blanton et al.
patent: 5010831 (1991-04-01), Halfhide
patent: 5517929 (1996-05-01), Repnik et al.
Bennett Henry A.
Tinker Susanne C.
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