JPS60228811A - Radiation energy burner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Industrial Application Fields Radiant energy burners use a combustion element that can be penetrated by gaseous fuel, and the fuel is burned on the outer surface of the element in a flameless type combustion in which no flame is produced. emits radiant energy. This type of burner allows you to obtain adequate combustion efficiency and
It is important to control the porosity and backpressure of the combustion element to minimize the possibility of blowback, or flame lift from the burner surface.

BACKGROUND OF THE INVENTION Traditionally, radiant combustion elements have consisted of an inner metal screen covered with a layer of randomly placed ceramic short fibers. This type of combustion element immerses the screen into a casting tank containing a liquid slurry of ceramic fibers.
It was manufactured by applying a vacuum through the screen and depositing the fibers in layers on the screen. This vacuum-formed ceramic m-fiber layer is brittle and extremely susceptible to damage during shipping and handling.

Problem to be Solved by the Invention During use, the short fibers in the vacuum-formed layer tend to dissociate over time, resulting in the combustion element having uneven porosity, which reduces combustion efficiency and burner life. Diminished.

Additionally, if the vacuum-formed IlII coating collapses due to damage or use, the combustion pattern may change abruptly and a shutdown may occur as the flame detector shuts off the system. Outage is not a dangerous condition, but it is a troublesome problem.

It is conventional to surround the combustion element with an external protective sleeve to protect the fragile vacuum-formed coating, as disclosed in U.S. Pat. No. 3,275,497.
No. 3,179,156. However, the use of an external protective screen substantially reduces the efficiency of radiant heating and adds unnecessary cost.

SUMMARY OF THE INVENTION The present invention is directed to a radiant Nerky burner having an improved combustion element. The combustion element generally preferably has a cylindrical metal screen or support member, with a sleeve of continuous ceramic fiber fabric disposed around the screen. The ends of the sleeve are fixed to the metal support member, while the central part of the sleeve is unfixed and free. In use, a blower supplies a gaseous fuel mixture inside the cylindrical support member, which flows outwardly through the support member and the fabric and burns on the outer surface of the fabric, primarily in the form of radiation. Release energy.

The woven ceramic fiber fabric is flexible and non-brittle, making it extremely durable for combustion elements to handle without damage.

Since woven fabrics are made of continuous fibers, there is no loss of fiber content during use, resulting in an extended useful life. The porosity of the woven fabric also aids in a substantially constant and uniform burn during use.

Also, different types of woven fabrics may be utilized to achieve the desired porosity depending on the particular application or use.

Since the woven fabric is not fixed to the metal support member over its entire length except at both ends, the difference in coefficient of thermal expansion between the woven fabric and the metal screen is not a limiting factor in service life. The woven fabric can compensate for the greater expansion of the screen at high temperatures. This is a substantial improvement over vacuum-formed ceramic layers that are deposited over the entire length of the metal support screen.

In the latter system, the difference in thermal expansion between the two materials creates stress within the vacuum-formed coating layer, causing cracking and destruction of the coating.

Embodiment FIG. 1 shows a combustion element 1 used in a radiant energy burner.
shows. The combustion element has a mounting flange 2 fitted and connected to a suitable support structure or housing and attached to the inlet conduit 3. A generally cylindrical porous metal support member or screen 4 is secured to the end of the conduit 3 and extends outwardly relative to the mounting flange. The end closing member 5 is fixed inside the outer end of the cylindrical screen 4 to close the outer end.

In the present invention, a woven sleeve 6 is provided around the slurry 24. Sleeve 6 is comprised of ceramic continuous fibers that can withstand temperatures in excess of 1800'F. For example, Su, 1J-7
6 is a metal oxide polycrystalline continuous fiber commercially available under the registered trademark NEXTE'L (manufactured by 3M Company), and the metal oxide contains 62% aluminum oxide, 14% boron oxide,
and 24% silicon dioxide.

Both ends of the sleeve 6 are connected to the screen 4 by a connecting assembly indicated by the reference numeral 7. Each coupling assembly 7
includes a conventional metal strap 8 disposed within an annular ceramic woven sleeve 9.

Sleeve 9 may be made of the same material as sleeve 6.

The annular sleeve 9 is provided with an opening and the tie strap 8
The free end of extends beyond the opening.

After the tie strap 8 is securely clamped to the sleeve 6, the protruding end of the tie strap is separated at the opening of the sleeve 9 so that the tie strap end is not exposed.

This type of coupling assembly 7 eliminates direct contact between the metal tie straps 8 and the cloth sleeve 6 and prevents wear on the sleeve 6 as the screen and sleeve expand during use. Furthermore, the outer layer of the annular sleeve 9 protects the metal strap 8 from the high temperatures caused by burner use.

As best seen in FIG. 3, a coupling assembly provided at the outer end of the screen 4, adjacent the end closure member 5, is located within a groove 10 on the screen 4.

The gaseous fuel mixture may be a mixture of natural gas, propane gas, etc., and air, and is passed through the conduit 3 by a blower to apply the necessary pressure to pass the gaseous fuel mixture through the woven sleeve 6 to the inside of the screen 4. will be introduced.

Fuel is supplied to the outside of the sleeve 6 using a standard ignition unit 1.
ignited by 1. As a result, flameless combustion occurs on the outer surface of the woven fabric sleeve 6, and radiant energy is mainly emitted.

The radiant burner according to the present invention can be used in many applications such as space heaters, furnaces, and water heaters. When used as a water heater, the radiant burner is enclosed within the heating chamber and does not come into direct contact with the water it heats.

Because the ceramic fiber nm cloth is a flexible material, it is extremely durable and eliminates the drawbacks previously encountered with vacuum formed combustion elements.

Roughly woven fabrics have the advantage that because they are composed of continuous fibers, shedding of fibers during use is eliminated, resulting in uniform porosity in the woven fabric over its entire life.

Since the sleeve is only fixed at both ends to the metal support member, the metal support member and the screen can expand relative to the woven fabric even at high temperatures. This is a substantial improvement over conventional vacuum formed fibrous elements in which the fibrous layer is fixed throughout the support member. In vacuum-formed elements, there is a substantial difference in thermal expansion between the ceramic lIi fiber material and the underlying metal support member of the vacuum-formed element, which causes stress in the fibrous coating, causing cracks and eventual failure. .

[Brief explanation of the drawing]

FIG. 1 is a side view with a partial cross-section of the combustion element of the radiant energy heater; FIG. 2 is a cross-sectional view taken along line 2--2 in FIG. 1; and FIG. 3 is a woven sleeve and metal support member. FIG. DESCRIPTION OF SYMBOLS 1... Combustion element, 2... Mounting flange, 3... Conduit, 4... Screen, 5... End closing member, 6...
... woven sleeve, 7... coupling assembly, 8...
Strap, 9... Sleeve, 10... Groove, 11
...Ignition unit. Patent Applicant Nie O. Smith

Claims (1)

[Scope of Claims] (1) A porous metal support member having an inner surface and an outer surface, a woven fabric made of substantially continuous ceramic fibers provided on the outer surface of the support member, and an end portion of the woven fabric. a coupling means for fixing the woven fabric to the supporting member in a free state without being fixed to the supporting member; and a supplying means including a blower for supplying the gaseous fuel through the supporting member and the woven fabric. and ignition means adjacent the outer periphery of the fabric for igniting the fuel. 2. A burner according to claim 1, wherein the metal support member is generally cylindrical and the weave is a cylindrical sleeve disposed around the support member. (2) The burner according to claim 2, wherein the coupling means comprises a ring-shaped coupling member for coupling both ends of the sleeve to the support member. (4) The burner according to claim 3, wherein the coupling member is a metal surrounded by a ring-shaped ceramic fabric. 6) a generally cylindrical porous metal support member having an inner end and an outer end, a closure member attached to the outer end of the support member, and a substantially continuous ceramic fiber; a flexible woven sleeve stretched over a substantial length of the support member over the outer surface of the support member; the ends of the sleeve being secured onto the support member and the portions of the sleeve disposed therebetween; coupling means for retaining the support member in a free and unanchored state; and a blower communicating with the inner end of the support member for supplying a gaseous fuel mixture into the interior of the support member. A radiant energy burner having a fuel element comprising a support member and a supply means flowing outwardly through the woven sleeve, and a fuel ignition means provided adjacent the outer surface of the sleeve for igniting the fuel. 6) A burner according to claim 5, wherein the coupling means comprises ring-shaped coupling members and a layer of woven ceramic material provided between each coupling member and the sleeve.