Radiant burner

Abstract

A radiant burner for treating an effluent gas stream from a manufacturing processing tool includes: a porous sleeve at least partially defining a treatment chamber and through which treatment materials pass for introduction into the treatment chamber; and an electrical energy device coupled with the porous sleeve and operable to provide electrical energy to heat the porous sleeve which heats the treatment materials as they pass through the porous sleeve into the treatment chamber. In this way, electrical energy, rather than combustion, is used to raise the temperature within the treatment chamber in order to treat the effluent gas stream.

Claims

1. A radiant burner for treating an effluent gas stream from a manufacturing processing tool, comprising: a porous sleeve at least partially defining a treatment chamber and through which treatment materials pass for introduction into said treatment chamber; and an electrical energy device coupled with said porous sleeve and operable to provide electrical energy to said porous sleeve such that the porous sleeve generates heat from the electrical energy through one of inductive heating, resistive heating and microwave heating, wherein the generated heat heats said treatment materials as they pass through said porous sleeve into said treatment chamber.

2. The radiant burner of claim 1, wherein said porous sleeve comprises at least one of an electrically conductive, a ceramic and a dielectric material.

3. The radiant burner of claim 1, wherein said porous sleeve comprises one of a sintered metal and a woven metallic cloth.

4. The radiant burner of claim 1, wherein said electrical energy device comprises at least one of a radio-frequency power supply, an electrical power supply and a microwave generator.

5. The radiant burner of claim 1, wherein said electrical energy device comprises a coupling coupled with said porous sleeve, said coupling comprising at least one of a radio-frequency conductor, an electrical conductor and a waveguide.

6. The radiant burner of claim 5, wherein said at least one of said radio-frequency conductor, said electrical conductor and said waveguide is located within a plenum through which said treatment materials pass, said plenum surrounding said porous sleeve.

7. The radiant burner of claim 5, wherein said at least one of said radio-frequency conductor, said electrical conductor and said waveguide extend over said porous sleeve to heat across its area.

8. The radiant burner of claim 4, wherein said radio frequency power supply provides radio frequency electrical energy using said radio frequency conductor to inductively heat said conductive material.

9. The radiant burner of claim 8, wherein said radio frequency electrical energy has a frequency of one of between 500 Hz and 500 KHz, between 20 KHz and 50 KHz and around 30 KHz.

10. The radiant burner of claim 5, wherein said porous sleeve is cylindrical and said radio frequency conductor coils around said porous sleeve.

11. The radiant burner of claim 5, wherein said radio frequency conductor is hollow to receive a cooling fluid to cool said radio frequency conductor.

12. The radiant burner of claim 11, comprising a humidifier operable to provide humidified air as said treatment materials and wherein said cooling fluid is circulated through said humidifier to heat water provided to said humidifier.

13. The radiant burner of claim 11, wherein said water provided to said humidifier comprises at least some of said cooling fluid.

14. The radiant burner of claim 1, comprising a porous thermal insulator through which said treatment material pass, said porous thermal insulator being provided in a plenum between said porous sleeve and said electrical energy device.

15. A method of treating an effluent gas stream from a manufacturing processing tool, comprising: passing materials through a porous sleeve for introduction into a treatment chamber, said porous sleeve at least partially defining said treatment chamber; and heating said treatment materials as they pass through said porous sleeve into said treatment chamber by supplying electrical energy to the porous sleeve so that the porous sleeve generates heat from the electrical energy using one of inductive heating, resistive heating and microwave heating, wherein the electrical energy is supplied to the porous sleeve by an electrical energy device coupled with said porous sleeve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the present invention will now be described further, with reference to the accompanying drawings, in which:

(2) FIG. 1 is a sectional view through a radiant burner assembly according to one embodiment;

(3) FIG. 2 is a sectional perspective view of features of a radiant burner in more detail with an inlet assembly removed; and

(4) FIG. 3 is a sectional view through a radiant burner according to a further embodiment.

DESCRIPTION OF THE EMBODIMENTS

(5) Before discussing the embodiments in any more detail, first an overview will be provided. Embodiments provide for an electrically-powered radiant burner, which enables an effluent gas stream from a manufacturing processing tool to be treated in situations where providing a fuel gas to raise the temperature of the treatment chamber is undesirable or simply not possible. Unlike traditional radiant heaters, which are unable to obtain the required power density, electrical energy is provided to heat treatment materials as they pass through the porous sleeve into the treatment chamber by heating the porous sleeve which considerably increases the power density and the achievable temperature within the treatment chamber.

(6) FIG. 1 is a cross section through a radiant burner assembly, generally 8, according to one embodiment. FIG. 2 illustrates features of the radiant burner in more detail with an inlet assembly removed. In this embodiment, electrical energy is supplied using inductive heating, although it will be appreciated that other heating mechanisms such as microwave heating or resistive heating are possible. FIG. 3 is a cross section through a radiant burner assembly, generally 80, according to a further embodiment with the inlet assembly in place. In this embodiment electrical energy is again supplied using inductive heating, although alternative heating mechanism, such as microwave heating or resistive heating are possible.

(7) The radiant burner assemblies 8, and 80, treat an effluent gas stream pumped from a manufacturing process tool such as a semiconductor or flat panel display process tool, typically by means of a vacuum-pumping system. The effluent stream is received at inlets 10. The effluent stream is conveyed from the inlet 10 to a nozzle 12 which injects the effluent stream into a cylindrical treatment chamber 14. In this embodiment, the radiant burner assembly 8, 80 comprise four inlets 10 arranged circumferentially, each conveying an effluent gas stream pumped from a respective tool by a respective vacuum-pumping system. Alternatively, the effluent stream from a single process tool may be split into a plurality of streams, each one of which is conveyed to a respective inlet. Each nozzle 12 is located within a respective bore 16 formed in a ceramic top plate 18, 118, which define an upper or inlet surface of the treatment chamber 14.

(8) The treatment chamber 14 has side walls defined by an exit surface 21 of a foraminous sleeve 20 in the form of a cylindrical tube. The foraminous sleeve 20 is made of a material which is suitable for the selected mode of heating. In this embodiment, inductive heating is used and so the foraminous sleeve 20 comprises a porous metal, for example sintered metal fibre, of a heat-resisting alloy, such as Fecralloy (Chromium, 20-22%; Aluminum, 5%; Silicon, 0.3; Manganese, 0.2-0.08%, Yttrium, 0.1%; Zirconium, 0.1%, Carbon, 0.02-0.03%; and the balance being Iron); stainless stesl grade 314 (Carbon 0.25% max, Manganese 2% max, Silicon 1.5-3%, Phosphorous 0.045% max, Sulphur 0.03% max, Chromium 23.0-26.0, Nickel 19.0-22.0, and the balance being Iron); or Inconel 600 (Ni minimum 72.0%, Cr 15.5%, Fe 8.0% Mn 1.0% C 0.15% Cu 0.5% Si 0.5% S 0.015%)

(9) The foraminous sleeve 20 is cylindrical and is retained concentrically within an insulating sleeve 40. The insulating sleeve 40 is a porous ceramic tube, for example, an alumina tube which may be formed by sintering an alumina slip which has been used to coat a reticulated polyurethane foam. Alternatively, the insulating sleeve 40 may be a rolled blanket of ceramic fibre. The insulating sleeve 40 helps to elevate the temperature within the treatment chamber 14 by reducing heat loss and also helps to reduce the temperature within the plenum 22 which in turn reduces the temperature of the components used for inductive heating to improve their efficiency.

(10) The porous ceramic tube and the foraminous sleeve 20 are typically 80% to 90% porous, with a pore size between 200 m and 800 m.

(11) A plenum volume 22 is defined between an entry surface 43 of the insulating sleeve 40 and a cylindrical outer shell 24. The plenum volume 22 is beneficially enclosed using non-ferromagnetic materials in order to reduce inductive coupling. In addition, the cylindrical outer shell 24 is concentrically enclosed within an outer insulating sleeve 60 in order to reduce the outer surface temperature to safe levels should the temperature of the cylindrical outer shell 24 become raised due, for example, to stray heating.

(12) A gas is introduced into the plenum volume 22 via an inlet nozzle 30. The gas may be air, or a blend of air and other species such as water vapour, CO.sub.2. In this example, humidified air is introduced and the humidified air passes from the entry surface 23 of the insulating sleeve 40 to the exit surface 21 of the foraminous sleeve 20.

(13) In this embodiment, an inductive heating mechanism is used and so the plenum volume 22 also contains a work coil 50 connected to a radio-frequency (RF) power supply (not shown) for heating the foraminous sleeve 20 by RF induction. The work coil 50 is typically a coiled copper hollow tube, cooled by circulation of a cooling fluid, for example water, with a low electrical conductivity, for example <100 S. If the supplied air is enriched with water vapour, then it may be beneficial to operate the cooling fluid at an elevated temperature so as to avoid condensation on the work coil 50. This may be achieved conveniently by use of a closed-loop circuit. As mentioned above, the insulating sleeve 40 serves as a thermal insulator to protect the work coil 50.

(14) Electrical energy supplied to the foraminous sleeve 20 heats the foraminous sleeve 20. This in turn heats the humidified air as it passes from an entry surface 23 of the foraminous sleeve 20 to the exit surface 21 of the foraminous sleeve 20. In addition, the heat generated by the foraminous sleeve 20 raises the temperature within the treatment chamber 14. The amount of electrical energy supplied to the foraminous sleeve 20 is varied to vary the nominal temperature within the treatment chamber 14 to that which is appropriate for the effluent gas stream to be treated. For example, the foraminous sleeve 20 (having an example diameter of 150 mm and an example length of 300 mm) is heated to between 800 C. and 1200 C. and the humidified air is likewise heated to this temperature. This is achieved by supplying electrical energy at a level of typically between around 10 kW and 20 kW applied to the foraminous sleeve 20 having the above example dimensions. This provides for a foraminous sleeve 20 surface area of 0.150.3=0.14 m.sup.2 and an equivalent power density of between around 70 kWm.sup.2 and 140 kWm.sup.2. The applied power is related to the flow rate of air through the foraminous sleeve 20. In this example, the air flow would be of the order of between around 300 l/min and 600 l/min. One skilled in the art would recognise that other conditions of power, air flow and temperature are possible. Typically, the radio frequency electrical energy has a frequency of between 500 Hz and 500 KHz, preferably between 20 KHz and 50 KHz and more preferably around 30 KHz. The effluent gas stream containing noxious substances to be treated is caused to mix with this hot gas in a known manner in the treatment chamber 14. The exhaust 15 of the treatment chamber 14 is open to enable the combustion products to be output from the radiant burner assembly 8 and received typically by a water weir (not shown) in accordance with known techniques.

(15) The further embodiment illustrated in FIG. 3 has an elongated top plate 118 which extends into the volume defined by a non-porous, non-ferromagnetic upper wall portion 220 of the sleeve 20. In this embodiment the work coils 50 and porous portion of the sleeve 20 are located distal from the seal 200. By locating the work coils at a suitable distance from the sealing surface comprising the seal 200 it is protected from heat generated by the work coil in the porous sleeve 20 transmitting to, and degrading, it. Locating the gas inlet 30 proximate to the surface comprising the seal 200, into the portion of the plenum 22 defined by the upper portion 220 of the sleeve 20 and the outer shell 24 also provides a further degree of protection for the seal 200 due to passage of gas across the surfaces thereof.

(16) Accordingly, it can be seen that the effluent gas received through the inlets 10 and provided by the nozzles 12 to the treatment chamber 14 is treated within the treatment chamber 14, which is heated by the foraminous sleeve 20. The humidified air provides products, such as oxygen (typically with a nominal range of 7.5% to 10.5%), as well as water (typically with a nominal range of 10% to 14%, and preferably 12%), depending whether or not oxygen enrichment occurs and on the humidity of the air, to the treatment chamber 14. The heat breaks down and/or the products react with the effluent gas stream within the treatment chamber 14 to clean the effluent gas stream. For example, SiH.sub.4 and NH.sub.3 may be provided within the effluent gas stream, which reacts with O.sub.2 within the treatment chamber 14 to generate SiO.sub.2, N.sub.2, H.sub.2O, NO.sub.x. Similarly, N.sub.2, CH.sub.4, C.sub.2F.sub.6 may be provided within the effluent gas stream, which reacts with O.sub.2 within the treatment chamber 14 to generate CO.sub.2, HF, H.sub.2O. Likewise, F.sub.2 may be provided within the effluent gas stream, which reacts with H.sub.2O, HF, H.sub.2O within the treatment chamber 14 to generate HF, H.sub.2O.

(17) Accordingly, embodiments provide a method and apparatus to combustively destroy waste gases from semiconductor-like processes utilising an RF induction heated porouswall combustion chamber.

(18) High power indirect heating is possible by induction heating. Providing the susceptor as a porous metal tube allows for the possibility of mimicking radiant burner combustion systems by allowing gas to be passed through and heated to a high temperature. This opens a way of giving burner-like performance with an electrical system.

(19) Embodiments can be varied to reflect the various nozzle and inject strategies employ in existing burners. The radiant burner element may be un-sintered ceramic fibre or, beneficially, sintered metallic fibre.

(20) In embodiments, microwave or resistive heating is used to heat the foraminous sleeve 20. In the case of microwave heating, a microwave generator is provided which couples with a waveguide located in the plenum volume 20 which conveys microwave energy to the foraminous sleeve 20 which is formed of a dielectric material. In the case of resistive heating, a power supply is provided which couples with a conductor located in the plenum volume 20 which conveys electrical energy to the foraminous sleeve 20 which is formed of a ceramic material.

(21) Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiment and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.

(22) Although elements have been shown or described as separate embodiments above, portions of each embodiment may be combined with all or part of other embodiments described above.

(23) Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are described as example forms of implementing the claims.