Ceramic gas fired hearth burner

Abstract

A ceramic hearth burner comprising a cast ceramic main body arranged to be situated within a fire place. The main body has a first chamber and a second chamber. A combustion air regulator is arranged to regulate the amount of air into the first chamber and an outlet is arranged for controlling the flow of fuel into the second chamber. An ignition plate encloses the second chamber which has a plurality of holes for releasing the fuel therein into an ignition area. At least one portal is arranged to channel the combustion air from the first chamber into the ignition area. The regulator is actuated by differential pressure in the ignition area and in the outside air, the pressure in the ignition area being varied by the amount of fuel being ignited.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to burner plate for a gas fired burner.

BACKGROUND

[0002] Companies that produce gas fired fireplaces and stoves strive to create the most realistic looking flame and burn pattern within their products. The goal is to emulate the look of a real wood burning fire while complying with emission limitations as specified by certification requirements. Manufacturers have 2 common choices in determining the construction of the gas burner.

[0003] A first choice may be tube burners which are constructed from steel tubing formed into a particular shape with burner ports cut along the length of the tube. Gas is fed into one area of the tube, called venturi or mixing tube. The gas stream pulls along with it a certain amount of air called primary air which is required for proper combustion. Secondary air which is required to complete the combustion process flows easily around the outside of the tube and towards the flame. These tube burners generally function well and are considered an economical burner setup. The limitation of the tube burners is that port arrangements can only follow the precise curvature or shape of the tube. In creating a realistic burn set-up this can be a very limiting option.

[0004] Another choice may be pan burners which are constructed mainly of steel resembling a thin rectangular shape with burner ports situated randomly around the top surface of the plenum. Gas is fed into the plenum through mixing a tube or venturi along with primary air. Artificial logs are then set on top of the burner with the burner ports arranged around the logs to create the effect of a real wood fire. Pan burners perform well but present a number of design constraints. Secondary air must be distributed to all burn areas. This is essential for clean burning or complete combustion. The larger the burner area the more difficult it is to feed combustion air to all burn areas. In difficult areas passageways must be made through the burner to allow combustion air to pass direction to the areas of combustion. This complicates the manufacturing process as these burners are fabricated from sheet steel and must be sealed either by pressing or welding all joining surfaces. A complex pan set-up will require many separate components and assembly will be more difficult. Welding is expensive and can present quality issues and warping. Pressing tools are expensive and make design alteration far more expensive and time consuming. Another design limitation is burner surface temperatures, which if excessive, limit the live expectancy of the burner. These burner set-ups are considered “top end” designs, which suit more expensive after market or retail units.

[0005] Manufacturers of gas appliances usually like to quote their appliances efficiency rating which places a further premium on operation efficiency. Efficiency of a gas appliance is specified as a percentage, calculated from the BTU input and final BTU output. This is a calculation of how much of the fuels potential heat value has actually been realised during the continued operation of the appliance. The calculation is a mathematical formula that takes into consideration the by-products of combustion and the exhaust stack temperature. In order to achieve a good efficiency, you have to have a minimum vent temperature combined with a good combustion. Good mechanical efficiency can be accomplished by a series of heat exchangers, which can absorb the temperature of the combustion gasses as they pass through. this heat is then distributed by a fan or even natural convection throughout the environment in which the appliance operates. Combustion efficiency is accomplished by reducing the emissions being exhausted by the unit. The more complete the fuel is combusted in the unit the lower the levels of by products will be within the flue gasses. The objective is to allow for complete combustion without using excessive combustion air. Excessive amounts of unused oxygen within the flue gas will lower the units overall combustion efficiency. In summary, mechanical efficiency through the use of heat exchangers can be expensive. These fabricated components are time consuming to manufacture. Combustion efficiency is accomplished through a precise burner set-up, which allows for thorough combustion with an efficient use of all combustion air. A good burner design will accomplish this without significant added cost of manufacture.

[0006] Efficiency ratings are taken while the units in a steady state operation. This rating is usually taken while the unit operates at its maximum output with a minimum vent configurations. These ratings do not take into consideration the units performance while operating at any other output setting or vent configuration. Most units today have an adjustable manifold input of 50% to 100% or commonly known as a 50% turn down. In actual fact, these units are most commonly used at some turn down state as the high heat setting provides more heat than is required by the home owner within the room they are installed. Experience, has proven that units that have an efficiency rating of 75% at the highest heat setting can have an operating efficiency of as low as 40% on the lowest heat setting. Direct vent units often require the use of restrictors to maintain efficiency, typically units installed in the field do not maintain there labelled efficiency as the unit is not correctly tuned (typically 15%-20% less). This is simply because the design aspects of the unit are static and are not self-adjusting depending on the operational conditions. The newest standards, which take into account practical operating situations, will state most units operation efficiency in more realistic terms.

SUMMARY

[0007] An advantage of the present invention is a design which allows the burner to occupy a large area of the fire box since secondary air does not have to be fed around the outside of the burner.

[0008] Another advantage of the present invention is the design is not susceptible to heat related deformation or deterioration.

[0009] The present invention operates at a good standard of efficiency without having to utilise expensive mechanical heat exchangers.

[0010] The present invention provides an arrangement with eases passing of integrity tests due to a much reduced volume below the burn surface.

[0011] The present invention will reduce quality concerns, as it does not require welding as a means of assembly or sealing.

[0012] The combustion air regulator will allow for sustained efficiencies through out the operating range and will automatically adjust for vent configurations without the need for additional restrictors.

[0013] The design of the present invention is cosmetically pleasing as it is not a welded assembly of components.

[0014] Manufacturers can concentrate on aesthetic designs and have burners built to suit their particular application.

[0015] According to the present invention there is provided a ceramic hearth burner comprising:

[0016] a cast ceramic main body arranged to be situated within a fire place;

[0017] a first chamber within the main body;

[0018] a second chamber within the main body;

[0019] a combustion air regulator arranged to regulate the amount of air into the first chamber;

[0020] an outlet for controlling the flow of fuel into the second chamber;

[0021] an ignition plate enclosing the second chamber;

[0022] a plurality of holes in the ignition place for releasing the fuel therein into a ignition area;

[0023] at least one portal arranged to channel the combustion air from the first chamber into the ignition area;

[0024] the regulator being actuated by differential pressure in the ignition area and in the outside air, the pressure in the ignition area being varied by the amount of fuel being ignited.

[0025] Preferably the regulator is a one way swing valve located at an open end of the main body at an air intake of the fireplace.

[0026] Preferably the holes are arranged in a pattern to simulate natural flames.

[0027] Conveniently the first chamber is located directly below the second chamber and the portals extends upwards through the second chamber and into the ignition area.

[0028] Preferably the ignition plate is removable from the main body.

[0029] Preferably the main body is a solid cast industrial ceramic material.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In the accompanying drawings, which illustrate an exemplary embodiment of the present invention:

[0031] FIG. 1 is a isometric view of the present invention.

[0032] FIG. 2 is a top plan view of the present invention.

[0033] FIG. 3 is an exploded isometric view of the present invention.

[0034] FIG. 4 is an isometric bottom view of the present invention.

[0035] FIG. 5 is a vertical cross section of the present invention mounted within a fire place.

DETAILED DESCRIPTION

[0036] Referring to the accompanying drawings, there is illustrated a ceramic gas fired hearth burner 1 arranged to be located within a flue 2 in a fire place 3. The burner is arranged to provide an aesthetically pleasing flame within the fire place as well as providing a highly efficient burning rate, as will be explained in detail.

[0037] The burner has a box 5 which is cast from industrial ceramic material. The box is rectangular in shape having an open bottom 7 and an open rear end 9. The rear end is arranged to regulate the flow of combustion air to the burner. A swing gate valve 11 extends along the length of the rear end at the air intake. The valve is opened and closed with relation to the atmospheric pressure from the air source to the flue pressure within the fire place. The valve hangs from a slot 13 cast into the ceramic burner in which a shaft 15 is located for supporting a valve plate 17. When the valve is open air is allowed to pass into a chamber of the box.

[0038] The box has a top chamber 19 and a lower chamber 21. The combustion air, indicated by arrow 23, is released into the lower chamber by the swing gate valve. The lower chamber has release portals 25 which extend upwards from the lower chamber through the top chamber into an ignition area 27 of the burner.

[0039] The top chamber is located directly above the lower chamber and is arranged to receive ignition gas though a outlet 29. The gas flows into the top chamber. The top chamber is enclosed by a burner plate 31 which has open sections 33 arranged to receive the air portals for releasing the air into the ignition area. The burner plate has a plurality of holes 35 which are selectively stamped into the plate to release the gas therethrough. The gas released through the holes is arranged to be ignited in the ignition area which is mixed with the combustion air such that a flame 37 burns in a selected pattern therein for aesthetic purposes. The selection of holes varies with the particular fire place but it is generally arranged to provide a natural looking burning pattern therein. The burner plate is detachable allowing to removable for various reasons such as maintenance or customisation.

[0040] The burner is intended for use within gas fired hearth products which will include direct vent, vented and vent less fireplaces and stoves. The burner is designed into new and existing units with little modification to various dimension aspects. The features, such as the combustion air regulation and burn pattern have a specific function and distinct commercial value. The burner design using the combustion air regulation limits the air movement through the burner. When the unit is operated at a reduced input or is subject to pressure differentials due to the vent configuration, the regulator automatically reduces the amount of combustion air entering the ignition area. This in effect keeps the ratio of air to fuel at a constant rate no matter which output setting the unit is operating at. This constant relation between fuel and air input will aid to sustain combustion efficiency. The burner can also be actuated by mechanical and/or electronic controls which monitor exhaust gases.

[0041] While one embodiment of the present invention has been described in the foregoing, it is to be understood that other embodiments are possible within the scope of the invention. The invention is to be considered limited solely by the scope of the appended claims.

Claims

1. A ceramic hearth burner comprises:

a cast ceramic main body arranged to be situated within a fire place;

a first chamber within the main body;

a second chamber within the main body;

a combustion air regulator arranged to regulate the amount of air into the first chamber;

an outlet arranged to control the flow of fuel into the second chamber;

an ignition plate arranged to enclose the second chamber;

a plurality of holes in the ignition place arranged to release the fuel within the second chamber into an ignition area;

at least one portal arranged to channel the combustion air from the first chamber into the ignition area;

the regulator being actuated by differential pressure in the ignition area and in the outside air, the pressure in the ignition area being varied by the amount of fuel being ignited.

2. The burner according to claim 1 wherein the regulator is a one way swing valve located at an open end of the main body at an air intake of the fireplace.

3. The burner according to claim 1 wherein the holes are arranged in a pattern to simulate natural flames.

4. The burner according to claim 1 wherein the first chamber is located directly below the second chamber and the portals extends upwards through the second chamber and into the ignition area.

5. The burner according to claim 1 wherein the ignition plate is removable from the main body.

6. The burner according to claim 1 wherein the main body is a solid cast industrial ceramic material.

7. The burner according to claim 5 wherein the ignition plate holes are arranged to provide a natural burning pattern during combustion therethrough.