Biomass pellet fuel heating device, system and method

Abstract

There is provided a pelletized-biomass combustion device comprising: (a) an elongate upright combustion capsule; (b) a grate element disposed within and bisecting the combustion capsule, (i) the grate element having a first side and a second side and (ii) the grate element open to fluid communication between the first side and the second side; (c) a first combustion air inlet facing the first side of the grate; (d) a second combustion air inlet facing the second side of the grate; (e) a fuel-feed inlet; and (f) a flue-gas exhaust outlet. The combustion capsule can be formed of two mated components such as a chamber housing mated with a burn pot member, or instead it can be formed as a single unit such as the chamber housing bisected by the grate. In any event, the grate element has two sides, and there are two combustion air inlets, each facing opposite sides of the grate. The combustion device is preferably an induced-draft system wherein the exhaust fan is positioned at the distal end of the stove pipe.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to biomass pellet fuel heating devices, some of which are at times called pellet burners, pellet burning stoves or pellet stoves, and related systems and methods.[0002]Pellet fuel heating devices are used in the USA and other countries. These heating devices, which include without limitation stoves, boilers and furnaces, burn pelletized wood and / or biomass fuels to produce heat. In comparison to natural-form wood burning devices, pellet burners generally have lower emission levels and higher combustion efficiencies. Pelletized fuel is also cleaner and easier to handle than natural-form wood, and is often derived from agricultural and industrial waste materials, including the waste of the timber industry.[0003]The efficiencies and environmentally-friendly features of current pellet fuel heating devices drive their rising popularity, but drawbacks and inefficiencies remain.[0004]The combustion of pellet fuels still produce...

AI Technical Summary

Benefits of technology

[0011]The present invention provides a pellet fuel heating device and system and method in which pellet fuel is combusted in a close mode, that is, in a constricted burn chamber, whereby thermal efficiency is dramatically increased while particulate emissions are substantially reduced.

[0012]The present invention also provides a pellet fuel heating device and system and method in which pellet fuel is combusted in a stoke mode, that is, in a dynamic environment, under stimulation or agitation force, whereby collection of pellets in heaps is avoided, leading to more complete combustion and reduction of particulate emissions.

[0013]The present invention in some embodiments also provides a pellet fuel heating device and system and method in which pellet fuel drops unhindered and unimpeded through a vertical feed conduit into the burn chamber, whereby the formation of a pellet continuum is precluded and the risk of burnback is eliminated. In some embodiments, a vertical pellet feed tube is coincident with an upper combustion feed tube whereby the pellet fuel is carried with a fast-flowing combustion air stream as it drops into the burn chamber.

[0014]The present invention also provides a pellet fuel heating device and system and method with an induced air draft system positioned at the stovepipe's external distal end, whereby the need for any forced-air blower within the core pellet stove is eliminated, together with the irritating sound of a fan operating within the core pellet stove and the risk of contamination of the interior environment presented by pushing flue gases into a stovepipe.

Problems solved by technology

The efficiencies and environmentally-friendly features of current pellet fuel heating devices drive their rising popularity, but drawbacks and inefficiencies remain.

Particulate matter is a primary component of smog and atmospheric pollution, and therefore its generation and release into the atmosphere is an environmental negative.

All of the current pellet delivery methods present a significant burnback risk.

Burnback is a serious and dangerous phenomenon in which the pellets within the hopper are ignited.

Burnback can occur when there is a sufficient trail of fuel between the combustion chamber and the hopper to bridge the two areas.

Such a fuel continuum can occur when the delivery pathway between the hopper and the combustion chamber is clogged with fuel, or fuel build-up.

Some current pellet fuel heating devices use just a natural draft system for exhausting flue gases, normally with poor results.

Ash and particulate build-up inside such small-diameter stovepipes quickly leads to draft reduction, which in turn brings about poor combustion and reduced thermal output.

Current forced-draft blower systems increase the air transfer, augmenting the combustion process in the burn chamber, but have significant drawbacks.

One drawback is the sound of the exhaust fans of these draft blower systems.

They are typically sufficiently noisy to be an irritant in residential and workplace settings.

Another drawback of current forced-draft blowers is the risk of contamination of the interior environment presented by pushing flue gases into a stovepipe.

Even a minor escape of flue gas from a stove pipe into a building's interior environment poses a dangerous health hazard.

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