WO2000079181A1

WO2000079181A1 - Improved burners and process of making

Info

Publication number: WO2000079181A1
Application number: PCT/US2000/017172
Authority: WO
Inventors: Daniel Preston
Original assignee: Daniel Preston
Priority date: 1999-06-22
Filing date: 2000-06-22
Publication date: 2000-12-28
Also published as: AU5758000A; WO2000079181A9

Abstract

Burners (10) and the process of making burners by laminating two or more layers (13, 14, 16, 18) of material having precise, and possibly complex, etched patterns (17) thereon to provide surface mix burners, pre-mix burners and pre-mix burner inserts with optimal combustion, homogeneous flame and a wide range of possible flame geometry, characteristics, densities, profiles and temperature control in a simple cost effective manner. Use of silicon wafer or metal alloy with a protective coating or an aluminium oxide forming alloy minimizes contamination of a workpiece and improves the lifetime of the burner (10, 22, 23) or burner inserts (16).

Description

IMPROVED BURNERS AND PROCESS OF MAKING

FIELD OF THE INVENTION

The invention relates to gas burners and the process of making burners for use in a variety of commercial and industrial applications.

BACKGROUND OF THE INVENTION

Commercial and industrial gas burners of varying sizes are used in a wide range of industries such as fiber optics, quartz, plastics, textiles, glass, metal, food, etc. Burners are generally constructed from brass, stainless steel or nickel chromium alloys. Different applications require different flame geometry, heat, temperature, etc. The temperature and heat output of a flame depends mainly on the type and amount, respectively, of fuel and oxidant being used. The type and configuration of flame, such as the size, length and shape, depends mainly on the construction of the burner and the fuel- oxidant mixture and flow.

There are two common classes of gas burners, surface mix and pre-mix. Surface mix burners isolate the fuel gas and oxidant such as air, oxygen, nitrous oxide, etc. until each flow through separate outlets of the burner. The fuel gas and oxidant mix on the exterior and above the surface of the burner, where they combust .

Most prior art surface mix burners isolate the fuel and oxidant by having a two concentric coaxial tubes construction.

Fuel gas is expelled from the inner coaxial tube and the oxidant from the outer concentric coaxial tube such that the fuel gas flow is surrounded by the oxidant flow and combustion occurs upon dispersion above the surface of the burner. U.S. Patent No. 5,112,219 to Scott Hiemstra ('219 patent) departs from the two concentric coaxial tubes construction of prior art surface mix burners by introducing a third concentric coaxial tube. The ^Λ219 patent discloses a surface triple mix burner having three concentric coaxial openings wherein the inner and outer coaxial tubes are provided with oxygen and the third middle coaxial tube is provided with hydrogen.

In comparison with other prior art surface mix burners having concentric coaxial outlets, U.S. Patent No. 4,477,244 to Nis et al. ('244 patent) discloses a surface mix burner wherein streams of fuel gas and oxygen from two separate set of orifices are radially directed to and mixed at a common point for combustion. In pre-mix burners, fuel gas and oxidant are mixed prior to exiting the burner for combustion. Flame control in pre-mix burners can be accomplished by altering the flow and ratio of fuel and oxidant. U.S. Patent No. 3,843,057 to Lorine Geiszler et al. ('056 patent) discloses a circular pre-mix burner having stacked layers of comb plates with fixed uniform outlets that provide symmetrical circular heating. Increased heat output can be achieved by increasing the fuel and oxidant input to the burners. Increasing the fuel and oxidant input in turn increases their exiting velocity. For pre-mix burners, if the velocity of the fuel-oxidant mix exiting the burner exceeds the propagation speed of the flame, the flame may lift away from the outlet of the burner. To prevent the flame from lifting off, pilot lights with a gas source having a lower velocity is maintained near the exiting port of the burner to ensure that the flame stays near the exiting port.

As illustrated in the 219, ^Λ244 and '05^ patents, conventional surface mix and pre-mix burners are constructed from numerous complicated parts, each construction for a specific application. Prior art burners are manufactured with machine tooling that are time consuming and costly and are limited both in the design possibilities and ultimate complexities. Furthermore, conventional burners are typically made of metal alloys, such as brass, stainless steel and nickel chromium alloys, which erode and can contaminate sensitive workpiece. When heated to a high temperature, stainless steel and nickel chromium alloys react with oxygen to form chromium oxide, a scale that does not adhere well to the base alloy. The chromium oxide flakes off the burner surface, contaminates the flame stream and can deposit and melt into the workpiece. Continuous use of such a burner at high temperature results in constant erosion. Thus, limiting the lifetime of the burner.

Therefore, there is a need for burners that are constructed in a simple and cost effective process that produces higher precision and more -sophisticatedly complex designs 'for burners having greatly improved efficiency, lifetime, flame geometry, flame characteristics, flame densities, flame profiles, etc. that would normally be impossible with a prior art process.

SUMMARY OF THE INVENTION

The invention provides a burner and the process of making burners in a simple and cost effective manner that allows precise, complex and infinite design possibilities for burners having improved efficiency, lifetime, flame geometry, flame characteristics, flame densities, flame profiles, etc.

The present invention, in particular, relates to burners and the process of making surface mix burners, pre-mix burners and pre-mix burner inserts by laminating two or more layers of material having etched patterns thereon to allow highly complicated and sophisticated custom designs of specific burners to create specific flame geometry, flame characteristics, flame densities, flame profiles and increased efficiency in a simple, cost effective manner. Furthermore, the burner of the present invention allows low-cost, rapid prototyping and manufacturing of custom designs.

A process of making a gas burner having at least two sheets of material, each sheet of material having a defined perimeter and at least one inlet and one corresponding outlet comprising the steps of: etching at least one sheet of material with a predefined pattern for conveyance of gas; etching at least one common opening within each of said predefined pattern defining said inlet on each respective sheet of material; providing at least one of said pattern to breach said perimeter of said corresponding sheet of material at least at one point for defining said outlet; and stacking said sheets of material such that each common opening is in alignment.

The burner of the present invention comprises at least first and second sheets of material stacked together, having at least one inlet and a corresponding outlet. The first sheet of material having a first etched depression pattern for conveyance of gas. The first depression pattern breach the perimeter of the first sheet of material at least at one point defining a first outlet. At least a first opening on the first sheet of material defining a first inlet. The first opening is within the first depression pattern such that gas entering the first inlet exits at the corresponding first outlet.

Additional sheets of material having different' depression patterns defining corresponding exclusive inlets and outlets may be provided to accommodate different gases or gases with different pressures and flows to be mixed at the burner outlets or for complicated manifolding of the gases. Stacking multiple sheets of material having the same or different depression patterns increases the number of outlets and the size of the burner. Different etched depression patterns when stacked together can produce outlets having different configurations, such as square, rectangular, circular, semi-circular or any other shapes. Additional sheets of material, each having an etched depression or etched through pattern that does not breach the perimeter of the sheet of material, may be added to form a heat exchanger using gas or water. Such etched depression or etched through pattern encompasses at least two openings defining an inlet and an outlet for the cooling agent. Alternatively, the pattern can breach the perimeter of the sheet of material to provide one or more side inlet and/or outlet.

A process of making a gas burner insert having at least two sheets of material, said burner having at least one pilot light comprising the steps of: etching at least two of said sheets of material with predefined pattern of one or more openings for passage of gas; providing at least one of said opening on each of said etched pattern with a predetermined size; impeding the gas flow on at least one of said sheet of material directed to said pilot light; stacking said sheets of material such that said predetermined sized opening on each of said etched pattern overlap to allow continuous gas flow and isolating said continuous gas flow from said pilot light gas flow.

The pre-mix burner insert of the present invention comprises at least first and second sheets of material stacked together, each sheet of material having respective first and second etched patterns to form one or more openings for passage of gas. A portion of the gas passes the second etched pattern of the second sheet of material exits the openings of the first sheet of material with a substantial decreased gas velocity for the pilot light gas source. The first pierced through pattern overlies at least a portion of the second pierced through pattern such that a portion of the gas exits at a lesser pressure drop and at a higher exiting velocity. The first pierced through pattern further isolates gas having a substantial decreased velocity from gas having a higher exiting velocity.

In a through leak embodiment of the pre-mix burner insert, gas velocity is impeded for the pilot light gas source by a second sheet of material having a pierced through pattern of minute holes that are substantially smaller than the remaining ports on the second sheet of material for gas exiting at a higher velocity. The minute holes constrict the gas flow. The first sheet of material has a pierced through pattern with corresponding pilot and port openings that match up with and isolate each minute holes and ports, respectively.

In another through leak embodiment, the second sheet of material has a partial depression pattern for conveyance of low velocity gas from a separate source and ports for gas exiting at a higher velocity. The first sheet of material has a pierced though pattern with corresponding openings and ports that match up with and isolate the low velocity gas and high velocity gas exiting the ports, respectively.

In a side leak embodiment of the pre-mix burner insert, gas velocity is impeded by allowing the gas to leak sideways through minute crevices. The crevices are formed by having a first sheet of material having etched through port and pilot openings over the second sheet of material having openings slightly larger than each port opening of the first sheet of material such that each openings overlap a small portion of the pilot openings of the first sheet of material. A third sheet of material having a pierced through pattern of port openings identical in size to the port openings of the first sheet of material forces the gas to travel a bending path and through the crevices sideways.

The surface mix and pre-mix burners and pre-mix burner inserts of the present invention may be made of laminated etched metal alloys, ceramic, quartz, glass, silicon wafers or other crystalline or amorphous element wafers. For sensitive applications such as fiber optic and semiconductor manufacturing, contamination of the flame stream is particularly important. Metal ion contamination in fiber optics and semiconductors can detrimentally interfere with their performances. To prevent contamination of the flame stream in sensitive applications, the burner of the present invention may be made of laminated etched silicon wafers. Although silicon is not a material that can be machined with any of the prior art methods to form a burner, the etching process of the present invention allow the making of a silicon based burner. As the workpiece in a fiber optic or semiconductor application is silicon based, it cannot be contaminated with a burner made of silicon wafer, which is typically pure single crystalline silicon up to ten decimal places in purity, i.e. 99.9999999999%. For non silicon based applications, the burner of the present invention can be made of metal alloys containing aluminum that form aluminum oxide upon oxidation, such as iron chromium aluminum, iron chromium aluminum yttrium or nickel chromium aluminum. At oxidizing temperature, these aluminum oxide forming alloys form a ceramic skin that adheres to the base alloy better than chromium oxide scale formed on conventional burners made of stainless steel and nickel chromium alloys.

Alternatively, metal alloys used in conventional burners that oxidize can be used for the burner of the present invention, or further improved on by first coating the metal with a protective layer by a plasma or chemical vapor deposition process to prevent carbonization, oxidation and erosion. Such a protective layer can be aluminum titanium nitride, zirconium nitride or silicon dioxide. Similar to the burner made of silicon wafers, a silicon dioxide coating is suitable for use with silicon based applications.

The etching process allows complicated etched patterns be produced on sheets of material in a precise, less time consuming and more cost effective manner than conventional machine tooling and methods of burner fabrication. Furthermore, the etching process allows low cost tooling and the ability to rapidly prototype and manufacture custom designed burners. Laminating sheets of material having various etched patterns thereon results in an unlimited variation of burners having precise, dense and complicated gas inlet and outlet designs for different applications and allows complicated manifolding for micro porting multiple combustion gases, oxidants and shielding gases.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the invention are delineated in detail in the following description. For clarification purposes, the hatching and cross-hatching patterns in Figures 2, 3, 5, 6, 11, 12, 13, 15, 16 and 24 represent partially etched through depressions and etched through openings, respectively, and are not cross-sectional views. In the drawings: Figure 1 is perspective view of a burner of the present invention having three inlets and nine sets of outlets.

Figure 2 is a front elevational view of an outer layer. Figure 3 is a front elevational view of an inner layer having a first etched depression pattern.

Figure 4 is a top plan view of Figure 3 illustrating the depression pattern.

Figure 5 is a front elevational view of an inner layer having a second etched depression pattern. Figure 6 is a front elevational view of an inner layer having a third etched depression pattern.

Figure 7 is a front elevational view of Figure 1 illustrating the stacked inner layers of Figures 3, 5 and 6.

Figure 8 is a front elevational view of an inner heat- exchanging layer for conveying cooling agents.

Figure 9 is a cross sectional view of Figure 8 taken along line 9-9.

Figure 10 is a front elevational view of a burner having an inner heat-exchanging layer and stacked inner layers having depression patterns similar to Figure 3, 5 and 6.

Figure 11 is a front elevational view of an inner layer having a fourth etched depression pattern.

Figure 12 is a front elevational view of an inner layer having a fifth etched depression pattern. figure 13 is a front elevational view of an inner layer having a sixth etched depression pattern.

Figure 14 is a front elevational view of Figure 1 illustrating the stacked inner layers of Figures 11, 12 and 13. Figure 15 is a front elevational view of an inner layer having a seventh etched depression pattern.

Figure 16 is a front elevational view of an inner layer having an eighth etched depression pattern.

Figure 17 is a top plan view of an internal ring burner of the present invention having annular laminations of respective depression patterns similar to Figures 3, 5 and 6 arrayed along the inner circumference. For clarity, some details may have been omitted.

Figure 18 is a top plan view of another internal ring burner of the present invention having 24 outlets arrayed along the inner circumference, each outlet directed to the center of the burner. For clarity, some details may have been omitted.

Figure 19 is a top plan view of another internal ring burner of the present invention having 24 outlets arrayed along the inner circumference, each outlet directed tangentially to a fixed diameter circle. For clarity, some details may have been omitted. Figure 20 is a top plan view of a leak through pre-mix burner insert of the present invention. Figure 21 is a top plan view of a layer having a second pierced through etched pattern having large port openings and small pinholes for use with the leak through pre-mix burner insert of Figure 20. Figure 22 is a top plan view of a layer having a first pierced through etched pattern having port and pilot openings.

Figure 23 is a cross-sectional view taken along line 23-23 in Figure 20.

Figure 24 is a top plan view of a layer having a third partially etched depression pattern for conveyance of slow velocity gas.

Figure 25 is a top plan view of a side leak pre-mix burner insert of the present invention.

Figure 26 is a top plan view of layer of having a fourth pierced through etched pattern having port openings for use with the side leak pre-mix burner insert of Figure 25.

Figure 27 is a top plan view of a layer having a fifth pierced through etched pattern having openings larger than port openings of Figure 22 for use with the side leak pre-mix burner insert of Figure 25.

Figure 28 is a cross-sectional view taken along line 28-28 in Figure 25. figure 29 is a top plan view of a leak through pre-mix burner insert of the present invention having a heat exchanger for conveying cooling agents.

It will be appreciated that, for purposes of illustration, these figures are not necessarily drawn to scale.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the drawings, wherein the same reference number indicates the same element throughout, there is shown in Figure 1 a perspective view of a burner 10 of the present invention.

As shown in Figure 1, burner 10 comprises of thirteen layers of material having three gas inlets Hi ...11₃ and nine sets of gas outlet orifices 12χ ... 12₉. The thirteen layers are shown to be stacked and held together by six threaded rods 13 passing through openings 15 on each layer and bolted on both ends. However, other methods known in the art, such as diffusion bonding, gluing, spot welding, welding, soldering or clamping can be used to hold the layers together. Pipes can be attached to inlets Hi ... 11₃ without brazing, i.e. silver soldering. A pipe end can be spot welded, fusion welded or capacitance discharge welded to inlets Hi ... 11₃ Dy using electrodes to make contact with the layer of material and the pipe end in a circular pattern to provide a leak free seal.

Figures 2 illustrates an outer layer 14 of burner 10 shown in Figure 1. Outer layer 14 has three inlet openings Hi ... 11₃ and six openings 15 adjacent to the perimeter of layer 14 to accommodate threaded rods 13 as shown in Figure 1. Inlet openings Hi - H3 and openings 15 are produced by photo etching, although other method known in the art, such as drilling or punching may be used. Figures 3, 5 and 6 illustrate a set of inner layers 16 with three different partially etched depression patterns 16A, 16B and 16C. Similar to outer layer 14, each inner layer 16 has three inlet openings Hi ... 11₃ to form the manifold and six openings 15 adjacent to the perimeter of each layer 16 to accommodate threaded rods 13 as shown in Figure 1. Depression pattern 16A exclusively encompasses and matches up with inlet opening Hi and extends to the perimeter of layer 16 to define a set of outlet orifices 12 of burner 10. Each inner layer 16 with depression pattern thereon defines three of the four walls of each set of orifices, with the fourth wall defined by an adjacent stacked layer, either an outer layer 14 or 18 or an inner layer 16 with the two depression patterns either face-to-face or both facing the same direction (face-to-back) . Outlet orifices 12 defined by two depression patterns race-to-tace are twice the thickness but half in the number of set of outlet orifices 12 for the same number of layers.

Depression pattern 16A includes eight closely adjacent grooves 17 perpendicular to the perimeter of layer 16, best shown in Figure 4. Similarly, depression patterns 16B and 16C each encompasses and matches up with an exclusive inlet opening 11₂ and 11₃, respectively, and extends to the perimeter of its respective layer 16. Each depression pattern 16B and 16C also includes eight grooves 17 perpendicular to the perimeter of layer 16 similar to depression pattern 16A. Grooves 17 extend to the perimeter of inner layers 16 to support collimated gas flow. However, grooves 17 can also be slightly recessed (not shown) from the perimeter to produce a wider ribbon flow.

Although the grooves 17 on patterns 16A, 16B and 16C are shown to be identical in number and width, they can vary from each other depending on the specific application of the burner 10. Furthermore, although partially etched patterns 16A, 16B and 16C are shown to be uniformly planar with rectangularized grooves, it may be non-uniform or curved with semi-circular grooves to alter the configuration of the outlet orifices 12 and thus altering the characteristics of the exiting gas or flame.

Depression patterns 16A, 16B and 16C are produced by photo etching, a process generally known in the art of semi-conductors and printed circuit board manufacturing. A photo-etching process converts a computer-aided design printed on a film onto a sheet of material by chemical processing. A photo resist is first applied to the sheet of material to be etched. One type of photo resist is hot rolled laminated onto the sheet of material. The film with the computer-aided design is then placed over the photo resist and exposed to light and then developed. The sheet of material with the pattern is then placed in an etchant, typically an acid or base for wet etching. Other methods of photo processing a resist on a sheet of material such as by X-ray, electron beam lithography, screening (silk or stencil), is contemplated. Photo etching includes wet etching, plasma etching and electro-chemical etching. One of these processes can be used to produce depression patterns for use with the present invention. Photo etching is able to produce extremely precise, uniform partially and fully etched patterns on a thin material. Photo- etching can produce depression or etched through patterns in less time and in a more cost effective manner than conventional machine tooling and can produce more complicated and intricate patterns not possibly fabricated with conventional machine tooling. It can be appreciated that a combination of multiple sheets of complicated etched patterns results in an even more complex laminated burner of the present invention. Furthermore, the tooling necessary to produce a burner of the present invention is almost immediate from the point of a computer-aided design to printing, exposing and then etching a sheet of material, which involves substantially less time than conventional tooling processes .

Burner 10 of Figure 1 comprises two outer layers 14, nine inner layers 16 and two additional outer layers 18 similar to outer layer 14 without the inlet openings Hi ... 11₃, acting as a blocking layer. The nine inner layers 16 include a selection from patterns 16A, 16B and 16C. With the thirteen layers stacked as shown in Figure 1, each groove 17 of each inner layer 16 form an exit slot 19 at outlet orifice 12. The configuration of the inner layers 16 limit gas introduced at inlet Hi to exit at an outlet orifice 12 corresponding to inner layer having pattern 16A. Similarly, gas introduced at inlets H₂ and 11₃ exit at an outlet orifice 12 corresponding to inner layer having patterns 16B and 16C, respectively.

Figure 7 illustrates the relative positioning of burner 10 of Figure 1 having inner layers 16 with all three depression patterns 16A, 16B and 16C. A burner having all three depression patterns 16A, 16B and 16C as shown in Figure 7 can be used as a surface mix, tri-mix, partial premix surface mix, full premix or a burner with inert reactive gas shields, etc. depending on the type of gases introduced at the three inlets llι-ll₃. The arrangement as shown in Figure 7 can also be used as a pre-mix burner with pilot lights by introducing oxygenated fuel gas having a lower velocity at one of the three inlets Hi ... 11₃ and oxygenated fuel gas at a high velocity at the remaining inlets Hi ... II3, such that outlet orifices 12 corresponding to lower velocity fuel gas provides the gas source for pilot lights. Alternatively, inner layers 16 of a surface mix burner can have the following pattern sequence: 16A-16A-16B-16B-16A-16A-16B- 16B-..., with each pair of patterns face-to-face forming one set of outlet orifices 12. For each pair of etched patterns 16A-16A facing each other, one of the pair's inlet llχ is flipped to the position of inlet 11₃ and thereby linking both inlets ll_x and H₃. This burner configuration can be used as a burner with three pairs of inlets Hi, H₂ and 11₃, a set of each inlet on opposite sides of the burner, without outer layers 14 or 18. Oxygen is introduced at the two inlets Hi and H₃ and fuel gas at the other inlet 11₂ to produce a sandwiching effect with alternating rows of oxygen and fuel gas at the outlet orifices 12. Similarly, this same geometry with half the outlet orifices 12 size can have the following pattern sequence: 16A-16B-16C-16B-16A-16B-16C-16B-16A- ..., with each pattern facing the same direction. Decreasing the size of the outlet orifices 12 in this manner improves combustion and laminar flow, resulting in a more uniform mixture of fuel gas and oxygen.

The surface mixing of alternating rows of extremely thin sheets of oxygen and fuel gas stacked extremely closed to each other provides a more uniform mixture of fuel gas and oxygen, resulting in optimal combustion, laminar flow and a uniform and homogenous flame. A burner having outlet orifices 12 ranging from 0.0075 inch to 0.015 inch in the thickness and spacing between rows of oxygen and fuel gas ranging from 0.0075 inch to 0.015 inch produces a flame many times denser and more heat than any prior art burners. Furthermore, the resulting flame is more homogeneous, perfectly uniform and continuous as opposed to prior art burners that produce distinct point zones. Additionally, the resulting flame is much sharper than prior art burners and has an incredible range, from about 0.005 inch to over 24 inches in length. Prior art burners with arrayed concentric tube designs produce less desirable bushy flames with uneven spots corresponding to the array pattern. Burners with extremely narrow outlet orifices 12 having a large surface area advantageously act as a fire check device when used in pre-mix or partially pre-mix burners, effectively stopping an explosion at the outlet orifices. When highly explosive mixtures such oxy-hydrogen, is used in pre-mix or partially pre- mix burners, the mixture may backflash. Backflash occurs when the fuel mix to the flame is adjusted to where it becomes explosive and the propagation speed of the explosion far exceeds the velocity of the flow and travels back through the burner towards the gas source. A backflash can be quite harmful, damaging or expioαmg the burner or even igniting the source. A fire check device stops the backflash by dividing the flame into many smaller ones that will then cool and extinguish. A typical fire check device is constructed by arraying many small tubes within a section of a larger tube where the fuel mix passes.

The following pattern sequence produces a surface mix burner with a different gas flow geometry at the outlet orifices 12: 16A-16C-16B-16B-16C-16A-16B-16B-16A-16C-... with every pair of patterns facing each other and being mirror image of the other, resulting in having only one inlet per pair. Oxygen is introduced at the two inlets Hi and 11₃ and fuel gas at the other inlet 11₂ to produce two rows of oxygen sandwiching each row of fuel gas. Similarly, this same- geometry with half the outlet orifices 12 size can have the following pattern sequence: 16A-16B-16C-16A- 16B-16C-..., with each pattern facing the same direction.

Decreasing the size of the outlet orifices 12 in this manner improves combustion and laminar flow, resulting in a more uniform mixture of fuel gas and oxygen.

Unlimited gas flow geometry can be created by stacking any number of inner layer 16 with patterns 16A, 16B and 16C in different sequence. Due to the offset inlets Hi and 11₃ of patterns 16A and 16C, the gas flow exiting at their respective outlet orifices 12 are tapered to the right and left, respectively. Pattern 16B having a centered inlet 11₂ has a gas rlow with a Gaussian profile, higher in the middle and equally tapering toward both edges. A burner having a Gaussian profile, such as those burners illustrated above, each pattern 16A or 16C must be balanced with another with an opposite tapered profile. Figure 8 is a heat exchanging inner layer 16 having an etched depression pattern 16D for dispersing a cooling agent. In comparison with depression patterns 16A, 16B and 16C, depression pattern 16D does not extend to the perimeter of layer 16 and includes two openings 20 and 21 (best shown in Figure 9) . Etched pattern 16D may be an etched through pattern (not shown) defining two walls of the heat exchanger, with the remaining two walls defined by adjacent stacked layers, either outer layers 14 or 18 or inner layer 16 using the surface opposite the depression pattern. An etched through pattern 16D advantageously allow stacking of one more such inner layers 16 to increase the capacity of the cooling agent, decrease flow resistance and have better control of the conductance.

Burner 10 as shown in Figure 1 may be adaptable for use with depression pattern 16D of Figure 8 by providing two additional openings 20 and 21 on each outer layers 14 and inner layers 16. Openings 20 and 21 are the inlet and outlet for a cooling agent such as gas, water or refrigerant. Inclusion of one or more layers having depression pattern 16D at any point in the stack of inner 16 and outer layers 14 and 18 depends on the need to cool an operating burner 10 to prevent damage to the burner. Depression pattern 16D alternatively can breach the perimeter of inner layer 16 at one or more point to provide side inlet 20 and/or outlet 21 for the cooling agent (not shown) . A heat exchanging layer 16 with pattern 16D is also important in applications where reactive organic material is being passed through the burner for a flame deposition process. Typically, such reactive organic material are stable over a narrow range of temperature only and hence the burner must be maintained within the appropriate range.

Figure 10 illustrates a burner 22 having inner heat- exchanging layers 16 having pattern 16D and inner layers 16 having depression patterns -similar to pattern 16A, 16B and l6C. Burner 22 differs from burner 10 of Figure 1 in a number of aspects. First, each layer 14, 16 and 18 has a substantially circular shape with a straight edge instead of a square shape. Second, burner 22 has an additional pair of inlet 20 and outlet 21 for the cooling agent. Third, pattern 16B has a narrower left- and rightmost outlet orifices 12 such that corresponding adjacent oxygen jet from patterns 16A or 16C overlap slightly more than burner 10 in Figure 1 when oxygen is introduced at inlets Hi and 11₃ and fuel gas at inlet 11₂, improving combustion at the edges of the outlet orifices 12 under some conditions. For burners using oxygen as an oxidant, high pressure oxygen can be used as a cooling agent prior to being used as an oxidant with a lower pressure via a Thompson-Joule refrigeration process. Heated oxygen exiting outlet 21 of the heat exchanger layer may be fed into inlets Hi and 11₃ for increased efficiency. Similarly, heated oxygen may be fed into the burner whether or not it was heated by passing through the heat exchanger or passing through a heat exchanger designed as a Thompson-Joule refrigerator. Figures 11, 12 and 13 illustrate a second set of inner layers

16 with three different depression patterns 16E, 16F and 16G. Similar to depression pattern 16A, depression pattern 16E encompasses exclusively inlet opening Hi and extends to the perimeter of layer 16 to define a set of outlet orifices 12 of burner 10. Depression pattern 16E includes six closely adjacent parallel grooves 17 at an angle to the perimeter of layer 16. Depression pattern 16F is identical to depression pattern 16B except with six grooves 17 instead of eight. Depression pattern 16G encompasses exclusively inlet opening 11₃ and is a mirror image of depression pattern 16E such that the six parallel grooves

17 are directed to the perimeter of layer 16 in the opposite direction at the same angle.

Figure 14 illustrates the relative positioning of burner 10 of Figure 1 having inner layers 16 with all three depression patterns 16E, 16F and 16G. In comparison with Figure 7, a burner 10 with depression patterns 16E, 16F and 16G not only produces a sandwiching effect of gases, but due to the alternating layers of exiting gas being askew to each other, vortices are created at each pair of outlet orifices 12 corresponding to patterns 16E and 16G. As patterns 16E and 16G are mirror image of each other, exiting gas from each are equally askew, creating vortices that travel along a vector perpendicular to the surface of the burner. Figures 15 shows another inner layer 16 with a different depression pattern 16H. Depression pattern 16H is similar to depression pattern 16B, except with four grooves 17 that are diverging instead of parallel. The two corresponding depression patterns of 16H can be identical to depression pattern 16H except for the exclusive inclusion of inlet opening Hi and 11₃, respectively

Figure 16 shows another inner layer 16 with a different depression pattern 161. Depression pattern 161 is similar to depression pattern 16H, except with three grooves 17 that are converging instead of diverging. The two corresponding depression patterns of 161 can be identical to depression pattern 161 except for the exclusive inclusion of inlet opening Hi and 11₃, respectively.. A burner utilizing inner layer 16 with depression pattern 161 directs the gas to different converging points exiting each exit slot 19. Depression pattern 161 can be modified to direct the gas exiting different slots 19 to converge at one focal point or other specific pattern.

As illustrated above, grooves 17 of the present invention are not necessarily perpendicular to the perimeter of the inner layer 16. Furthermore, it is contemplated that grooves 17 can be non-linear and not uniformly distributed on the pattern.

Although the burner 10 as shown in Figure 1 is a square block of square-shape inner and outer layers 14, 16, and 18, it is not so limited and each inner and outer layers 14, 16 and 18 can be of various sizes and shapes. Furthermore, inner layers 16 of a burner 10 of the present invention can have a variety of combinations from any of the etched patterns 16A-16I or others not shown. The ability to manipulate the inner layers 16 with various depression patterns, number of inner layers, number of manifolding inlets and types of gases introduced at the inlets 11 provide an unlimited variation of exiting gas pattern for specific applications.

For example, Figure 17 illustrates an internal ring burner 23 utilizing annular inner layers 16, each inner layer 16 having eight equally distributed depression patterns substantially similar to 16A, 16B, 16C and 16D along the inner circumference.

Figure 18 illustrates another internal ring burner 24 having annular inner layers 16 having depression pattern 16J, 16K and 16L. Pattern 16J has twenty-four equally distributed tips for fuel gas, each radially directed to the center of the circular burner 24. Pattern 16J encompasses a plurality of inlets 11 . Pattern 16K has twenty-four tips having wider outlet orifices 12 than pattern 16J for oxygen, each radially directed to the center. Figure 18 illustrates a simple representation of fuel gas and oxidant flow directed and end at a concentric circle for clarification purposes, although in normal operating conditions, the fuel gas and oxidant flow are continues and the oxidant jet flow is not visible. Pattern 16K encompasses a plurality of inlets H5. Pattern 16L is annular with a plurality of inlets 20 and outlets 21 for conveyance of a cooling agent.

Figure 19 illustrates yet another internal ring burner 25 similar to burner 24 shown in Figure 18 except that each depression pattern 16J is directed tangentially at a concentric circle 26 to create a different exit gas pattern than burner 24. The size of the concentric circle 26 can vary by altering the angle of the outlet orifices 12 of depression pattern 16J. Similar to Figure 18, Figure 19 illustrates a simple representation of fuel gas and oxidant flow for clarification purposes. Such complex design is not possible with prior art and offers additional advantages. For example, ring burners can be problematic in a horizontal position because the rising heat treats the workpiece unevenly. The tangential design of burner 25 can be further manipulated by having each stacked annular layer 16 rotationally offset to form helical outlet orifices such that a spiraling heat flow is created to induce more even heat and to carry away the exhaust. Figure 20 is a pre-mix burner insert 27 of the present invention providing a flow through pilot leak. In comparison with burner 10 of Figure 1, pre-mix burner insert 27 has a horizontal lamination. As shown in Figure 20, burner insert 27 has a plurality of ports 28, each port 28 being surrounded by six hexagonal pilot openings 29, one for each pinhole 30. Any number of pilot openings 20 can be used to correspond each port 28, depending on the specific application and the density of pilot lights required. Burner insert 27 comprises at least two pierced through layers 31 of material having two different etched patterns 31A and 31B, as shown in Figures 21 and 22, respectively. The two layers 31 are shown to be stacked and held together by six micro bolts and nuts 32 and two registration pins (not shown) passing through openings 33 on each layer (as shown in Figures 21 and 22) . Due to the required precision in stacking layers 31 to properly align patterns 31A and 31B, micro bolts and nuts 32 with sufficient precision are used. Openings 33 must have sufficient tolerance for micro bolts and nuts 32, which are about 0.003 inch oversized, creating a slight spacing. Alternatively, registration pins with a higher accuracy of 0.00001 inch can ensure exact alignment. Other methods known in the art, such as diffusion bonding, gluing, spot welding, welding, soldering or clamping can be used to hold the layers together.

Figure 21 is a bottom layer 31 of burner insert 27 having pierced through etched pattern 31A. Pattern 31A comprises a plurality of uniformly distributed circular ports 28. Each circular port 28 has six corresponding pinholes 30 equidistant from port 28 and from adjacent pinholes 30. Each pinhole 30 preferably is as small as 0.001 to 0.002 inch in diameter and each circular port 28 substantially wider, such as 0.045 inch in one embodiment. The diameter of port 28 and array geometry can vary based on the specific application of burner insert 27.

Figure 22 is a top layer 31 of burner insert 27 having pierced through etched pattern 31B. Pattern 31B comprises a plurality of uniformly distributed circular ports 28 identical in diameter and position to those of pattern 31A. Adjacent and surrounding each circular port 18 are six hexagonal pilot openings 29. Each hexagonal pilot opening 29 corresponds to a pinhole 30 of pattern 31A, as shown in Figure 20. When bottom and top layers 31 having patterns 31A and 31B are stacked as burner insert 27, as shown in Figure 20, each hexagonal pilot opening 29 of pattern 31B forms a wall around each pinhole 30 (best shown in Figure 23) . Top layer 31 having pattern 31B acts as a top screen over layer 31 having pattern 32A. Pilot openings 29 are shown to be hexagonal in shape to provide maximum density, however, other shapes such as pentagon, octagon, circular, triangle, etc., can be substituted without detracting from the spirit of the invention.

Figure 23 illustrates how gas flows through burner insert 27. Gas flowing through burner insert 27 is substantially constricted by pinholes 30 due to their small diameter, but gas flow are only slightly impeded at ports 28 with a substantially wider diameter. Impeded gas flow 34 flows at a lower velocity through pinholes 30 and advantageously becomes the gas source for pilot lights. Pilot openings 29 are wider in diameter than pinholes 30 to provide a larger pilot flame area. Pilot openings 29 isolate the impeded gas source 34 exiting each pinhole 30 from higher velocity gas source 35 exiting each port 28.

Pierced through etched patterns 31A and 31B are produced by photo-etching. In comparison with conventional machine tooling, photo-etching is able to produce pinholes 30 having diameters as small as a few hundred thousandths of an inch in any desired pattern evenly dispersed around ports 28 of pattern 31A and hexagonal pilot openings 29 closely adjacent to ports 28 of pattern 31B without damaging the material itself. Photo-etching of a pierced through pattern, especially one with minute openings such as pinholes 30, are best performed on a thin material, which maximum thickness is generally known in the art of photo-etching. However, the overall thickness of burner insert 27 is preferably to be at least three times the diameter of port 28 to produce a good collimated gas flow at ports 28. Therefore, layers 31 of burner insert 27 may comprise of multiple layers of each of the patterns 31A and 31B to add up to an appropriate thickness as a burner insert 27.

Figure 24 illustrates an alternative bottom layer 31 for the through leak pre-mix burner insert 27 of Figure 20 with a partial depression pattern 31C for conveyance of low velocity gas. Pattern 31C comprises a plurality of uniformly distributed circular ports 28. Surrounding the circular ports 28 is a depression pattern having two inlets 36 for low velocity gas. More or less inlets 36 can be accommodated. Low velocity gas entering inlets 36 can be from a separate source or from a Thompson-Joule refrigeration process after passing through a heat exchanging layer having pattern 31F in Figure 29. Each port 28 is isolated from the low velocity gas by a cylindrical wall 37. Similar to pre-mix burner insert 27 shown in Figure 20, when top layer 31 having pattern 31B is placed over bottom layer 31 having pattern 31C, slow velocity gas passes through pilot openings 29 while gas with a higher velocity passes through ports 28.

Figure 25 is another embodiment of a pre-mix burner insert 38 of the present invention providing a side pilot leak. Similar to burner insert 27 of Figure 20, burner insert 38 has a plurality of ports 28, each port being surrounded by six hexagonal pilot openings 29. Burner insert 38 comprises three pierced through layers 31 of material having three different etched patterns 31B, 31D and 31E, as shown in Figures 22, 26 and 27, respectively. Similar to burner insert 27, top layer 31 having pattern 31B acts as a top screen. The three layers 31 are shown to be stacked and held together by six bolt and nuts 32 and two registration pins (not shown) passing through openings 33 on each layer (as shown in Figures 22, 26 and 27) . However, other methods known in the art, such as diffusion bonding, gluing, spot welding, welding, soldering or clamping can be used to hold the layers together. Figure 26 is a bottom layer 31 of burner insert 38 having pierced through etched pattern 31D. Pattern 31D is identical to pattern 31A of burner insert 27, but without pinholes 30. The diameter of each circular port 28 can vary based on the specific application of burner insert 38.

Figure 27 is a middle layer 31 of burner insert 38 having a pierced through etched pattern 31E. Pattern 31E comprises a plurality of uniformly distributed side leak openings 39, similar to ports 28 of pattern 31D. Each side leak opening 39 is a concentric circle slightly larger in diameter than port 28 extending just beyond the edges of hexagonal pilot openings 29 surrounding each port 28 of pattern 31B, best shown in Figure 25. The oversized side leak openings 39 create crevices 40 for gas to leak sideways into the pilot openings 29. The diameter of side leak openings 39 governs the conductance of crevices 40 and the amount of gas flow supplied to pilot openings 29.

Figure 28 illustrates how gas flows through burner insert 38. Gas first passes through port 28 of pattern 31D, then through side leak opening 39 of pattern 31E. A small amount of gas flow 41 flows through crevice 40 from side leak opening 39 into pilot openings 29, with the remaining gas 42 flowing through port 28 of pattern 31B. Due to the small crevice 40 and the bending path traveled by gas flow 41, the gas flow 41 in pilot openings 29 has a lower velocity than gas flow 42 and advantageously becomes the gas source for pilot lights. Pilot openings 29 isolate the impeded gas source 41 exiting crevices 40 from gas source 42 having a higher velocity exiting ports 28. As illustrated by gas flow 41, layer 31 having pattern 31D acts as a blocking plate to prevent gas from flowing directly to pilot openings 29 of top layer 31 having pattern 31B.

Figure 29 is a pre-mix burner insert 43 of the present invention providing a flow through pilot leak similar to insert 27 of Figure 20, but with a cooling facility. Cooling facility is provided by having an additional etched depression pattern 31F on either layers having a pierced through pattern identical to 31A or 31B. Depression pattern 31F comprises two openings 44 and 45 as the inlet and outlet, respectively, for a cooling agent such as gas, water or refrigerant. Inclusion of one or more layers with pattern 3IF depends on the need to cool an operating burner insert 43 to prevent damage to the insert under certain applications. A Thompson-Joule refrigeration process can be utilized for the heat exchanger by piping high pressure oxygen or other gases through the inlet 44 before exiting outlet 45 for use with layer 31 having pattern 31C of Figure 24 as low velocity gas for pilot lights.

The precise patterns produced by photo etching allows control over the amount and the pattern of gas flow to produce pre—mix burner inserts having better combustion, a sharp and homogenous flame, increased flame pattern densities, specific flame geometry and profiles, etc.

The layers of material 14, 16, 18 and 31 used for the burners of the present invention as described above may be made of any metal alloy. Metal alloys used in conventional burners oxidize in a way that may contaminate the workpiece and decrease the life of the burner. An improvement over the metal alloys used in conventional burners is to first coat it with a protective layer by a plasma or chemical vapor deposition process. This coating provides a controlled surface instead of allowing the base alloy to oxidize to form an uneven coating that is dependent on the alloy to prevent carbonization, oxidation and erosion. Plasma and chemical vapor deposition processes are generally known in the art of semiconductor processes. An appropriate protective layer can be refractatory oxides, nitrides or carbides, such as aluminum titanium nitride, zirconium nitride or silicon dioxide. Coatings and base alloy reactions can be further modified by preconditioning or firing in a controlled atmosphere furnace. Silicon dioxide coating is particularly suitable for use with silicon based applications such as fiber optics or semiconductors.

Each layer of materials may also be a silicon wafer having etched patterns thereon for assembly as a burner of the present invention. Because silicon wafer are cut from a single crystal, the stacked silicon wafer can easily and advantageously be fused together by processes generally known in the art of semiconductors, such as diffusion bonding, which causes the crystal to merge together as one crystal with no lamination boundary to form one unitary unit. For example, a burner of the present invention can be constructed from pure undoped silicon wafers of 100 crystal orientation and 0.017 inch in thickness.

The layers of material 14, 16, 18 and 31 used for the burners of the present invention may also be made of metal alloys having an aluminum oxide forming content, such as iron chromium aluminum, iron chromium aluminum yttrium or nickel chromium aluminum. These aluminum oxide forming alloys form a ceramic skin that adheres well to the alloy at oxidizing temperature. In particular, iron chromium aluminum yttrium forms a sub-oxide under the aluminum oxide of yttrium that further enhances the refractatory properties and adheres better to the base metal than aluminum oxide alone. A burner of the present invention made of aluminum oxide forming alloys can also be first preconditioned to evenly and completely form a ceramic skin on the alloy to protect the burner and diffusion bond the layers together.

Although certain features of the invention have been illustrated and described herein, other modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modification and changes that fall within the spirit of the invention.

Claims

CLAIMSWhat I claim is:

1. A gas burner having at least one inlet and at least one corresponding outlet, comprising: at least two sheets of material stacked together, each sheet of material having a defined perimeter; at least one sheet of material having a predefined pattern forming a path for conveyance of gas; each sheet of material with a predefined pattern having at least one common opening; each of said pattern encompassing at least one of said common opening defining said inlet; and at least one of said pattern breaches said perimeter of said corresponding sheet of material at least at one point defining said outlet.

2. The gas burner of claim 1 further comprising at least one sheet of material having no pattern and no common opening so as to act as a blocking layer.

3. The gas burner of claim 1, wherein said pattern forming a path for conveying gas is etched.

4. The gas burner of claim 3, wherein said etched pattern is an etched depression pattern.

5. The gas burner of claim 3, wherein at least a portion of said etched pattern is an etched through pattern.

6. The gas burner of claim 4, wherein said etched pattern is planar such that said outlet having a rectangular-shaped cross- section

7. The gas burner of claim 4, wherein said etched pattern is non-planar.

8. The gas burner of claim 4, wherein at least one of said etched pattern having one or more grooves directing the flow of said gas at said outlet.

9. The gas burner of claim 8, wherein each of said groove is perpendicular to said perimeter of said respective sheet of material such that said gas travels orthogonal to said perimeter.

10. The gas burner of claim 9, wherein said one or more grooves define one or more rectangular slots at said outlet.

11. The gas burner of claim 8, wherein each of said groove is askew to said perimeter of said respective sheet of material such that said gas said travels at an angle to said perimeter.

12. The gas burner of claim 1, wherein each of said common opening is mutually exclusive within said respective predefined etched pattern.

13. The gas burner of claim 4, further comprising at least one of said etched pattern that does not breach said perimeter of said corresponding sheet of material for conveyance of a cooling agent and having two common openings defining an inlet and an outlet for said cooling agent.

14. The gas burner of claim 5, further comprising at least one of said etched pattern for conveyance of a cooling agent that breaches said perimeter at least at two points defining a side inlet and a side outlet for said cooling agent.

15. The gas burner of claim 1 wherein said sheet of material is made of metal alloy.

16. The gas burner of claim 1 wherein said sheet of material is made of silicon.

17. The gas burner of claim 10 wherein at least a portion of each of said etched pattern overlaps each other such that at least some of said slots are closely adjacent to each other.

18. A burner having at least one inlet and one corresponding outlet comprising two or more sheets of material stacked together, at least one of said sheet of material having an etched pattern therein defining said inlet and said outlet.

19. A surface mix burner having at least two inlets and two corresponding set of outlets for conveyance of at least two gases comprising: a body having a top surface; two or more openings on said body defining said inlets; and two or more sets of slots on said top surface defining said outlets, said outlets being closely adjacent such that said two gases exiting said burner are orthogonal to said surface forming at least two sheets of gas flow closely adjacent each other.

20. A process of making a gas burner having at least two sheets of material, each sheet of material having a defined perimeter and at least one inlet and one corresponding outlet comprising the steps of: etching at least one sheet of material with a predefined pattern for conveyance of gas; etching at least one common opening within each of said predefined pattern defining said inlet on each respective sheet of material; providing at least one of said pattern to breach said perimeter of said corresponding sheet of material at least at one point for defining said outlet; and stacking said sheets of material such that each common opening is in alignment.

21. The process of claim 20 further providing an end sheet of material with no etched pattern and no common opening to act as a blocking layer.

22. The process of claim 20 wherein said etching is accomplished by photo etching.

23. The process of claim 22 wherein said etching is accomplished by wet etching.

24. The process of claim 22 wherein said etching is accomplished by plasma etching.

25. The process of claim 22 wherein said etching is accomplished by electro-chemical etching.

26. A gas burner insert having at least one pilot light comprising: at least two sheets of material stacked together; each sheet of material having a predefined pattern of one or more openings for passage of gas; at least one of- said opening on each of said overlapped pattern being in alignment and having a predetermined size to allow continuous gas flow; at least one of said pattern having means for impeding gas flow directed to said pilot light; and said one or more openings of at least one sheet of material isolate said continuous gas flow from said pilot light gas flow.

27. The gas burner insert of claim 26 wherein said pattern for passage of gas is etched.

28. The gas burner insert of claim 27 wherein said etched pattern is an etched through pattern.

29. The gas burner insert of claim 27 wherein at least a portion of said etched pattern is an etched depression pattern.

30. The gas burner insert of claim 28 wherein said gas impeding means comprising at least one hole substantially smaller in size than said predetermined sized opening for continuous gas flow for passage of said pilot light gas flow.

31. The gas burner insert of claim 28 wherein said gas impeding means comprising an opening slightly larger in size than said predetermined sized opening for continuous gas flow and overlaps a small portion of said opening for pilot light gas flow to create a crevice for passage of said pilot light gas flow.

32. The gas burner insert of claim 31 wherein said gas impeding means further comprising at least one sheet of material having a pattern of one or more openings of said predetermined size such that continuous gas flow traveled a bending path passing through said crevice sideways into said opening for pilot light gas flow.

33. The gas burner insert of claim 29 wherein each of said material having a defined perimeter, said gas impeding means comprising an etched depression pattern breaching the perimeter of said sheet of material at least at one point for inputting a low velocity gas for said pilot light.

34. The gas burner insert of claim 29 wherein each of said material having a defined perimeter, at least one of said etched pattern convey a cooling agent, said etched pattern breaches the perimeter of said sheet of material at least at two points for the inputting and outputting of said cooling agent.

35. The gas burner insert of claim 26 wherein said sheet of material is made of metal alloy.

36. The gas burner insert of claim 26 wherein said sheet of material is silicon.

37. The gas burner insert of claim 26 wherein said sheet of material is made of quartz.

38. The gas burner insert of claim 26 wherein said sheet of material is made of ceramic.

39. A process of making a gas burner insert having at least two sheets of material, said burner having at least one pilot light comprising the steps of: etching at least two of said sheets of material with predefined pattern of one or more openings for passage of gas; providing at least one of said opening on each of said etched pattern with a predetermined size; impeding the gas flow on at least one of said sheet of material directed to said pilot light; stacking said sheets of material such that said predetermined sized opening on each of said etched pattern overlap to allow continuous gas flow and isolating said continuous gas flow from said pilot light gas flow.

40. The process of claim 39 wherein said etching is accomplished by photo etching.

41. The process of claim 40 wherein said etching is accomplished by wet etching.

42. The process of claim 40 wherein said etching is accomplished by plasma etching.

43. The process of claim 40 wherein said etching is accomplished by electro-chemical etching.

44. A burner to minimize contamination of said burner's flame stream made of an aluminum oxide forming alloy.

45. The burner of claim 44, wherein said aluminum oxide forming alloy is iron chromium aluminum.

46. The burner of claim 44, wherein said aluminum oxide forming alloy is iron chromium aluminum yttrium.

47. The burner of claim 44, wherein said aluminum-oxide forming alloy is nickel chromium aluminum.

48. A burner made of metal alloy having a protective coating deposited by a vapor deposition process to minimize oxidation and erosion of said burner.

49 The burner of claim 48, wherein said protective coating is a refractatory nitride.

50. The burner of claim 49, wherein said refractatory nitride is aluminum titanium nitride.

51. The burner of claim 49, wherein said refractatory nitride is zirconium nitride.

52. The burner of claim 48, wherein said protective coating is a refractatory carbide.

53. The burner of claim 48, wherein said protective coating is a refractatory oxide.

54. The burner of claim 48, wherein said protective coating is silicon dioxide.