WO1994020799A1

WO1994020799A1 - Space heater

Info

Publication number: WO1994020799A1
Application number: PCT/US1994/002444
Authority: WO
Inventors: Delbert F. Carver
Original assignee: Lb White Company Inc; L B White Co Inc
Current assignee: Lb White Company Inc; L B White Co Inc
Priority date: 1993-03-09
Filing date: 1994-03-08
Publication date: 1994-09-15
Anticipated expiration: 1995-09-09
Also published as: CA2097888A1

Abstract

A compact high efficiency space heater (14) is provided. The space heater (14) includes an exterior shroud (22), electrical (34) and gas (36) control assemblies, a burner (80), plenum (40) and a blower assembly (56). Efficient combustion is achieved by a burner (80) and gas inlet orifice (68) combination which produces a turbulent flow and mix of gas and combustion air in the burner (80). The plenum (40) includes a baffle (52, 54) arrangement, along with ventilating air inlet (48), to insure that the heated output is cooled to a selected level.

Description

SPACE HEATER

Technical Field The present invention relates to furnaces or space heaters. In particular, it relates to a gas burning space heater having features for promoting efficient combustion and controlling the temperature of the output whereby the space heater may be used safely in livestock and poultry barns.

Background of the Invention U.S. Patent 4,773,848 (to Jalbert and Carver, the latter inventor being the inventory of the present invention) discloses a furnace for use in the relatively hostile environment of livestock and/or poultry barns. These environments are hostile in the sense that they contain active animals, animal byproducts, bedding, feed, chemical disinfectant and treatment agents, and large amounts of suspended paniculate matter. The furnace disclosed in the '848 patent has a sealed gas control valve to shield the valve from the environment.

Breeding and incubation areas or rooms of livestock and poultry barns are where heat is particularly needed. Such areas are often small, confined spaces, this limited space imposes at least three further constraints on space heaters. First, the heater unit must be located a substantial distance from any combustible surfaces or the output temperature must be lowered from the combustion temperature, about 850°- 1 ,000° F, to an acceptable level to avoid fire danger. Second, because space heaters generally are not vented to the exterior of the space in which they are being used, high efficiency combustion is necessary to reduce the level of toxic combustion byproducts released into the small area. Third, the overall size of the heater should be minimized to avoid using up valuable space. It would be advantageous to achieve a safe, highly efficient agricultural confinement heater that occupies as little space as possible. U.S. Patent 3,653,371 (to McManus) is directed to providing a furnace with an L-shaped burner to reduce the size of the furnace. According to this patent, a burner mixing tube or duct must have a relatively long axial dimension to promote mixing the gas and air particles prior to combustion; the longer the tube, the more complete the mixing and combustion. The burner disclosed in the '371 patent purportedly enables a smaller furnace, yet meets the mixing tube length requirement by bending the tube into two generally perpendicular planes. The disclosed burner also enables a 180° direction change in the gas flow, purported to provide a stable even flame across the entire length of the burner and a distribution and diffusion of air and fuel gas that provides core complete combustion. The heater disclosed in the above-noted '848 patent includes a burner with long tube or neck, generally following the mixing tube length teachings of the McManus patent, and therefore is not as compact as possible.

Other methods of reducing size and increasing furnace efficiency are known. For example, dampers may be provided in the flu or the air-to-fuel ratio may be precisely controlled. U.S. Patent 3,280,744 discloses an orifice plate of preselected cross section and draft limiting features to control the air-to-fuel ratio and, thus, promote efficiency.

The space heater of the present invention is small, yet provides high efficiency combustion. Broadly, this is accomplished by using a combustion burner with an inverted (what would normally be thought of as the base of the cone is at the top of the burner), generally flattened frusto-conical shape and a gas supply nozzle having openings or ports designed to direct that gas against the wall of the burner thereby providing turbulence and thoroughly mixing the gas and combustion air before igniting it.

U.S. Patents 2,524,047 (to Frese et al.) and 3,850,373 (to Grolitsch) disclose that it is known to direct a stream of material against a deflecting surface to accomplish an objective. However, the Frese et al. patent is directed to an improved fire extinguishing apparatus wherein a deflecting surface is used to direct a fire extinguishing material into a blanket for covering a large area. The

Grolitsch patent is directed to providing a device for atomizing. There is no teaching in either patent that such devices might be used to mix combustible gas and air to provide more efficient combustion in furnaces.

It would be advantageous if a safe, highly efficient agricultural confinement heater that occupies as little space as possible were available. Summary of the Invention

The present invention provides for a compact yet highly efficient agricultural confinement space heater. The space heater comprises an exterior shroud, electrical and combustion gas control assemblies, a burner, a plenum or burn chamber and a blower assembly. Highly efficient combustion is achieved by the burner of the present invention in combination with the gas orifice, the plenum of the space heater includes a baffle arrangement, along with air inlets, to insure that the heated output of the heater is adequately cooled to a predetermined level.

More specifically, a preferred embodiment of the burner for the heater of the present invention is generally frusto-conically shaped having a combustion air intake opening at its base and an output exhaust slit at its upper end. Oriented generally vertically in the heater, the burner is flattened, having a height greater than its width, and does not include a long gas and air mixing tube. A gas delivery orifice fitting is mounted adjacent the base opening and includes at least two ports, at least one of which is angularly related relative to the wall of the burner whereby the combustible gas introduced into the burner from the ports is directed against the wall of the burner rather than straight into and linearly up in the direction of the uppermost discharge slit. This combination produces a turbulent flow of gas and combustion air rather than a laminar flow thereby creating a homogeneous mixture of gas and air and increasing the efficiency of the combustion occurring in the burner.

Another feature of the present invention is a burn chamber or plenum having an integral baffle structure whereby the flow pathway of the heated air through the plenum is lengthened to reduce the temperature from approximately 800-1000° F at the burner discharge slit to about 350° F at the heated air outlet of the heater. Additionally, the plenum includes at least one, but preferably two, ventilating cool ambient air inlets along the pathway to further cool the heated air before it is discharged into the environment.

An object of the present invention is to provide a space heater for agricultural confinement areas typically found in livestock or poultry breeding barns, for temporary heating at construction sites, or for garages.

Another object of the present invention is to provide a compact space heater having a burner and gas delivery orifice for delivering fuel to the burner, the burner and orifice combination producing highly efficient combustion, and having a plenum or after-burn chamber for providing a hot air flow path which cools the hot air from the combustion temperature to a predetermined standard level safe for both livestock and the structure housing the space heater.

Yet another object is to provide a space heater operable on natural, butane or propane gas at various pressures and flow rates, at various altitudes or atmospheric pressures and to produce a selected output temperature. Still another object of the present invention is to provide a space heater having a burner, a plenum burn chamber and a blower assembly wherein the blower assembly induces the flow of combustion air into the heater, enhances the turbulent mixture of combustion gas and combustion air within the burner, and rapidly moves the heated air through the plenum. Other objects, features and advantages of the present invention will become more apparent and understood with reference to the following specification and to the appended drawings and claims.

Brief Description of the Drawings Fig. 1 is a perspective view of the heater of the present invention; Fig. 2 is a front elevational view of the heater with parts cut away to reveal the heated air flow path through the heater;

Fig. 3 is a sectional view thereof taken along line 3-3 in fig. 2; Fig. 4 is a right side elevational view of the burner of the heater of the present invention; Fig. 5 is a front elevational view of the burner;

Fig. 6 is a top plan view of the burner, depicting an alternative exhaust slit in phantom; Fig. 7 is a elevational view of the gas orifice fitting of the present invention;

Fig. 8 is a top plan view of the orifice; Fig. 9 is a sectional view taken along line 9-9 in Fig. 8; Fig. 10 is a top plan view of an alternate embodiment of the orifice having additional gas emitting ports; and

Fig. 11 is an elevational view of the orifice depicted in Fig. 10.

Detailed Description of the Preferred Embodiment Referring to the drawings, a direct gas-fired circulating space heater 14 for use in agricultural buildings includes a heater body 15, electrical and fuel control assemblies 16, and a burner assembly 18.

Referring particularly to Fig. 1 , the space heater 14 in accordance with the present invention includes an exterior heat-shielding casing shroud 22 with detachable end panels 24, 26. The shroud 22 is connected to a heater base plate 30 and supports a hot air discharge assembly 32 and an electrical power supply junction box 34. A sealed gas valve box 36 is also supported by the base 30 and shroud 22. The shroud 22 is removable from the base 30 for servicing, and the end panels 24, 26 are removable from the shroud. The end panels 24, 26 may be provided with plurality of apertures 38 creating a grill effect, and at least one of the end panels, panel 24, does not entirely occupy or close the end of the heater

14, thereby leaving an air inlet and access opening into the heater.

The outer shroud 22 of the heater body 15 provides an outer heat shield skin and may be formed of appropriate gauge stainless steel, galvanized or aluminized steel, or other appropriate materials. Referring to Figs. 2 and 3, the shroud 22 provides an interior cavity for containing a combustion bum chamber or plenum 40. The plenum 40 preferably is formed from 20-gauge stainless steel, although other appropriate gauges and material may be used as well. The plenum 40 may be fabricated as a stand alone, walled unit and mounted to the bottom base 30 in an appropriate fashion, or it may be formed integrally with the base 30, as an extension thereof. The plenum 40 is spaced inwardly from the outer shroud 22 to provide an air space 42 for insulation purposes and air flow and heat exchange purposes. At one end the plenum 40 includes ambient combustion air inlet opening 44, and at the other end has a heated air output opening 46. the plenum 40 also includes an auxiliary ventilating or cooling opening 48 in the rear wall .and a second such opening 50 in the bottom wall. A first integral baffle deflector plate 52 is fixed in the plenum 40 generally perpendicular to the air flow from the inlet 44 toward the output opening 46 (the flow is depicted by a plurality of arrows in

Figs. 2 and 3). A second larger baffle deflector plate 54 is also in the plenum 40 and is generally perpendicular to the first baffle plate 52.

A blower assembly 56 is mounted on the base 30 at the end of the plenum 40 opposite the intake 44. The blower assembly 56 is generally contiguous with the end wall of the plenum 40 carrying the outlet opening 46. The assembly 56 includes a blower motor 58, a blower housing 60 and a "squirrel cage" impeller or blower 62 mounted in the housing 60 and operatively connected to the motor 58. The blower assembly 56 generates a negative pressure inside the plenum 40 and creates the heated combustion air flow depicted by the arrows in Figs. 2 and 3. It should be appreciated that the deflector baffle plates 52, 54 contribute to the cooling of the heated combustion gases by providing a labyrinth or convoluted flow path. Additional cooling of the hot combustion gases is provided by the ventilating air drops or openings 48, 50 in the walls of the plenum 40.

Referring back to Fig. 1 , the burner assembly 18 of the heater 14 of the present invention includes gas lines 64 connected between a commercially available gas control valve 66 (depicted in phantom) and a single hexagonal burner orifice fitting 68 mounted adjacent the base 30.

Referring to Figs. 7-11 , the burner orifice 68 includes a body 70 having a generally central bore or cavity 72. One end 74 of the orifice body 70 is threaded to accept a gas line 64, as usual. Adjacent the opposite closed end 76, the orifice body 70 is provided with individual drilled gas ports 78. The ports 78 are drilled at a specific angle relative to the orifice longitudinal axis (i.e., 70°, as shown at angle B in Fig. 7).

Figs. 10 and 11 depict another embodiment of the burner orifice fitting 68'. The second embodiment 68' is substantially similar to the embodiment 68 depicted in Fig. 78, but includes more gas ports 78', four are depicted. In this fitting embodiment 68', two ports 78' are drilled at angle C, preferably 70°, and the two ports 78' closest to the threaded inlet end 74 are drilled at 90°. the use of either the two port orifice fitting 68 or the four port orifice fitting 68' relates to the type and pressure or input rate of the gas fuel being used. The orifice fittings 68, 68' are preferably formed of brass but other suitable material may be used as well. Referring to Figs. 4-6, the burner assembly 18 includes a burner 80. the burner's position relative to the heater 14 is represented in at least Fig. 2. The burner 80 includes mounting structures 82, 82' for connecting it to the end wall of the plenum 40 with customary fasteners. The burner 80 has an inlet end 84 and an output or combustion exhaust end 86. The inlet portion 84 is immediately adjacent to the orifice 68 and is substantially open to receive ambient air, drawn inwardly into the plenum 40 by the blower assembly 56. The flow of ambient air is depicted at arrows F in Fig. 2. At its upper outlet end 86, the burner 80 includes a hot combustion air discharge slit 88, best seen in Fig. 6. A second embodiment of the burner 80, wherein the slit 88' is narrower than the slit 88, is depicted in phantom. Between the inlet end 84 and the exhaust end 86, the body

90 of the burner 80 defines the actual burning chamber. The burner is generally frusto-conically shaped, yet flattened near its upper end 86. The burner wall forming the body 90 comprises basically a single continuous surface tapering upwardly and outwardly away from the inlet end 84 in one orientation (see Fig. 5), and tapering inwardly and upwardly in the orientation depicted in Fig. 4.

Referring to Fig. 5, mounting apertures 92 may be provided on the flat sides of the burner 80 for connecting appropriate monitoring or auxiliary equipment to the burner 80.

Additional components and controls such as meters, control switches and sensors, specific electrical components, specific gas conduit components and burner components are commercially available and installed or used in their customary fashion, as disclosed in U.S. Patent 4,773,848, the disclosure of which is incorporated herein by reference. An example of such an additional component is a second high temperature limit switch similar to the type used with the furnace disclosed in the '848 patent.

In use, gas flows in response to thermostat control, and from the orifice 68 through the ports 78 as depicted in figs. 4 and 5. The blower assembly 56 acts to pull ambient air for combustion purposes into the inlet end 84 of the burner 80 and into the plenum 40 in the direction of arrows F depicted in Fig. 2.

One of the objectives of the present invention is advantageously achieved by the orifice fitting 68 and the angled ports 78. This advantage is depicted in Fig. 4 wherein gas being admitted into the burner 80 from the port 78, along with ambient air, is directed against the wall of the burner 80. As suggested by arrows D in Fig. 4, the impact of the gas on the wall redirects the gas and produces a turbulent flow toward upper end of the burner 80. The turbulence is increased as ambient air is drawn inwardly by the blower assembly 56, thereby producing inside the burner 80 a thorough mix of ambient air and gas. The result is very efficient combustion producing exhaust gases with a carbon monoxide level of 6- 12 parts per million (ppm).

With regard to the second embodiment of the orifice fitting 68' depicted in Figs. 10 and 11 , the number of ports 78' in the orifice fitting 68' depends on the type of fuel being used (natural gas, propane gas, or butane gas), the desired heat output (in BTU's) and the atmospheric pressure.

The width or size of the exhaust slit or opening 88 (or 88') at the top of the burner 80 as depicted in Fig. 6 is a variable feature and contributes to the efficiency of the heater 14. The size is selected relative to the desired output, the fuel, and to insure that there is no backdown bu inside the burner 80.

The objective of producing a space heater for use in confined areas is accomplished in the present invention in large part due to the design and features of the plenum 40. Specifically, with reference to Figs. 2 and 3, initiating the blower assembly 56 produces a negative pressure in the plenum 40, drawing ambient air and the heated combustion air into the plenum 40. the flow of heated combustion air is along a convoluted air flow path. The blower assembly 56 also draws additional ventilating or cooling air through the air inlets or air drops 48, 50. these features enable the heated combustion air, at approximately 800-1,000° F at the top of the burner 80, to be cooled to a temperature less than 350° plus ambient temperature at the discharge duct 32. An additional feature that contributes to the safe use of the heater 14 in small areas is that the outer heat shield shroud 22, and particularly the way the plenum 40 is set inside the shroud

22, eliminates "hot spots" on the heater 14.

The heater 14 of the present invention includes several models based on desired heat output (in BTU's). For all models of the present invention, commercially available components, some of which (e.g., the burner) may be specifically designed, include:

Burner Single piece cast iron

Combination Control Robertshaw model 7200ERB-3 or

Honeywell model VR8300 Air Proving Switch Micro-Switch (Honeywell) model V3L-3287-D8 Transformer Basler Electric, Class II, 120-24V

High Limit Switch Therm-o-disc model L350F

Fan Motors General Electric model 5KCP39EG-L418S

General Electric model 5KSP29FG-7321S Pilot Assembly Robertshaw model HS780

Electronic Ignitors Carbo model 0206FC007 Norton model 271

Electrical & Gas Control Enclosures Freeman Chemical Corp., polyurethane plastic with foam seals

Data and specifications of one selected model of the heater 14 areas follows:

Model 60 Natural Gas Propane Gas

Max. Input Rating (Btu/hr) 60,000 60,000

Min. Input Rating (Btu/hr) 28,000 32,000 Manifold Pres. - High (in.wc/kPa) 5.6/1.39 11.0/2.74

Manifold Pres. - Low (in.wc/kPa) 1.5/.37 3.3/.82

Port Size (DMS) (4) #50 (2) #56 (2) #57

Max. Inlet Pres. (in.wc/kPa) 7.5/1.87 14.5/3.61

Min. Inlet Pres. (in.wc/kPa) 5.5/1.37 11.8/2.93

It should be appreciated that the heater 14 may be adapted to be used with various fuels, atmospheric pressures and fuel flow pressures (e.g., by changing the number and size of the ports, by changing the horsepower of the blower motor, etc.). The preceding table is intended to be exemplary. The space heater 14 of the present invention might take different forms within the scope of the invention. The outer configuration of the heater 14 may be changed; various peripheral items such as additional sensors or warning indicators for blower malfunction, overheating or appliance malfunction may be provided; a timed post-bum purge feature may in incorporated with the blower assembly 56; the material for forming the heater body 15, the plenum 40 and the burner 80 may be selected from appropriate materials; mounting features such as apertures in the top of the shroud 22 may be provided to hang or otherwise mount the heater 14; and various indicia or instructions for the mounting, operation and safety may be provided on the exterior surfaces of the heater 14.

It will be seen that a cost effective, safe and efficient method of heating areas is provided by the space heater of the present invention. The invention may be easily installed in existing buildings or it may be used in new construction. The present invention may be embodied in other specific forms without departing from the central attributes thereof. Therefore, it is desired that the described embodiments be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than to the foregoing description to indicate the scope of the invention.

Claims

What is claimed is: 1. A space heater comprising: a combustion burner having a wall, a base with an inlet for ambient air to enter said burner and an exhaust slit opposite said base; a nozzle means for introducing a combustible fluid into said combustion burner, said nozzle means being mounted adjacent to said inlet and having at least one port for directing said combustible fluid against said wall to turbulently mix said combustible material and ambient air; and means for igniting said mix, thereby producing heated combustion air.

2. The space heater according to claim 1 and shroud containing a blower housing and a chamber defining a heated combustion air flow pathway extending generally from said inlet to a heated combustion air exit, said chamber including baffle means for lengthening said pathway.

3. The space heater according to claim 2, and an opening along said pathway between said inlet and said exit for admitting ventilation air into said heated combustion air flowing in said pathway.

4. The space heater according to claim 3, and blower means for pulling ambient and ventilation air into said openings, for moving said heated combustion air along said pathway, and for blowing said heated combustion air from said space heater.

5. A burner assembly for use in a gas fired heater, said burner assembly comprising: a burner having a base with an inlet opening, a tope with an exhaust slit and a substantially continuous burner wall extending between said inlet and said slit, said burner being generally frusto-conically shaped; and orifice means for introducing gas into said burner, said orifice means being adjacent to said inlet opening and having at least one port means for directing a flow of said gas toward said wall.

6. The burner assembly according to claim 5, wherein said heater comprises a plenum containing baffle means for creating a convoluted air flow path through said plenum, said plenum having at least one ventilating air inlet along said flow path.