TWI682127B - Radiant burner - Google Patents

Abstract

A radiant burner and method are disclosed. The radiant burner is for treating an effluent gas stream from a manufacturing process tool, the radiant burner comprises: a sintered metal fibre sleeve through which combustion materials pass for combustion proximate to an inner combustion surface of the sintered metal fibre sleeve; and an insulating sleeve surrounding the sintered metal fibre sleeve and through which the combustion materials pass. In this way, a radiant burner is provided which does not crack due to rapid cycling caused by frequent idle steps during which the burner is extinguished. Also, by providing an insulating sleeve, the temperature within the radiant burner and the temperature of an outer surface of the radiant burner remain comparable with existing ceramic burners. This enables the radiant burner to be substituted in place of existing ceramic burners as a line-replaceable unit which does not suffer from cracking during such frequent and short-duration periods of process tool inactivity.

Description

Radiation burner

The invention relates to a radiant burner and method.

Radiation burners are known to us and are commonly used to treat an exhaust stream from one of the manufacturing process tools used in, for example, the semiconductor or flat panel display manufacturing industry. During this manufacturing period, residual perfluorinated compounds (PFC) and other compounds are present in the exhaust stream pumped from the process tool. It is difficult for PFC to be removed from exhaust gas and release them into the environment, which is undesirable because they are known to have a relatively high greenhouse effect.

Known radiant burners use combustion to remove PFC and other compounds from the exhaust gas stream. Generally, the waste gas stream is a nitrogen stream containing one of PFC and other compounds. A fuel gas is mixed with the exhaust gas flow and the gas flow mixture is delivered to a combustion chamber laterally surrounded by the outlet surface of a porous gas burner. Fuel gas and air are simultaneously supplied to the porous burner to affect flameless combustion at the outlet surface, wherein the amount of air passing through the porous burner is not only sufficient to consume the fuel gas supplied to the burner but also to inject into the combustion chamber All combustibles in the airflow mixture.

Although there are technologies for treating exhaust gas streams, each of them has its own disadvantages. Therefore, it is desirable to provide an improved technique for treating an exhaust gas stream.

According to a first aspect, there is provided a radiant burner for treating an exhaust gas stream from a manufacturing process tool. The radiation burner includes: a sintered metal fiber sleeve A tube through which the burning material passes to burn near a combustion surface in one of the sintered metal fiber sleeves; and an insulating sleeve that surrounds the sintered metal fiber sleeve and the burning material passes through the insulating sleeve.

The first aspect recognizes that in order to improve the energy efficiency of the process or to reduce the exhaust gas flow, it may be desirable to extinguish the radiant burner during the period of inactivity of the process tool that typically occurs during the process idle step. However, the first aspect also recognizes that these idle steps can be frequent and have a short duration, and this rapid cycle can cause premature failure of the existing radiant burner sleeve or bushing due to rupture.

Therefore, a radiant burner can be provided. The radiant burner can treat or reduce a stream of exhaust gas discharged or discharged from a manufacturing process tool. The radiant burner may include a metal fiber sleeve that may be sintered, and the combustion material may pass through the metal fiber sleeve to burn at a combustion surface near or adjacent to one of the metal fiber sleeves. The radiant burner may also include an insulating sleeve, which may surround or at least partially surround the metal fiber sleeve. The burning material can also pass through the insulating sleeve to reach the metal fiber sleeve. In this way, a radiant burner is provided, which during its extinction will not be broken due to the rapid cycle caused by frequent idle steps. In addition, by providing an insulating sleeve, the temperature in the radiant burner and the temperature on the outer surface of one of the radiant burners are kept comparable to the existing ceramic burners. This allows the radiant burner to replace the existing ceramic burner as a field replaceable unit, and the radiant burner will not suffer from rupture during frequent and short duration periods of inactivity of the process tool.

In one embodiment, the sintered metal fiber sleeve has a porosity of 80% to 90%.

In one embodiment, the sintered metal fiber sleeve has an air permeability of 150 to 300 cc/min/cm ² .

In one embodiment, the sintered metal fiber sleeve has a density of 690 to 1110 kg/m ³ .

In one embodiment, the insulating sleeve is a ceramic fiber coating.

In one embodiment, the insulating sleeve has a density of 100 to 150 Kg/m ³ .

In one embodiment, the insulating sleeve has a density that provides a pressure drop of 40 to 60 Pa as the burning material passes therethrough.

In one embodiment, the sintered metal fiber sleeve is held coaxially within the insulating sleeve.

In one embodiment, the radiant burner includes a support operable to hold the sintered metal fiber sleeve and the insulating sleeve.

In one embodiment, the insulating sleeve is held coaxially within the support.

In one embodiment, the sintered metal fiber sleeve includes circumferentially extending pleats. Providing a pleat helps to adapt to changes in the dimensions of the sintered metal sleeve at different temperatures.

In one embodiment, the radiant burner includes a temperature sensor that is thermally coupled to the sintered metal fiber sleeve and is operable to provide an indication of a temperature of the sintered metal fiber sleeve . Therefore, an indication of the temperature of the metal fiber sleeve can be provided so that the operating temperature of the radiant burner can be established.

In one embodiment, the temperature sensor and the sintered metal fiber sleeve are thermally coupled to an outer surface. Therefore, a temperature sensor can be provided outside a combustion chamber defined by the metal fiber sleeve in order to protect the temperature sensor from the materials in the combustion chamber.

In one embodiment, the radiant burner includes a source operable to supply the burning material with one of a selected plurality of mixing ratios responsive to temperature. Therefore, the mixing ratio of these burning materials can be responded to temperature changes in order to optimize the operating conditions and/or temperature of the radiant burner.

In one embodiment, the source is operable to supply the combustion material at a substantially stoichiometric mixing ratio when the temperature of the sintered metal fiber sleeve fails to exceed an operating temperature. Therefore, in order to improve the warm-up time of the radiant burner, a stoichiometric or Material rich mixing ratio.

In one embodiment, the source is operable to supply the combustion material at a substantially lean mixing ratio when the sintered metal fiber sleeve exceeds an operating temperature. Therefore, once the appropriate operating conditions are reached, the fuel content can be reduced.

According to a second aspect, a method of operating a radiant burner for processing an exhaust stream from a manufacturing process tool is provided, the method comprising: determining an outer surface temperature of a sintered metal fiber sleeve of a radiant burner , The burning material passes through the sintered metal fiber sleeve to burn near the combustion surface in one of the sintered metal fiber sleeves; and the burning material is supplied in one of a plurality of mixing ratios selected in response to the temperature.

In one embodiment, the supply includes supplying the combustion material at a substantially stoichiometric mixing ratio when the temperature of the sintered metal fiber sleeve fails to exceed an operating temperature.

In one embodiment, the supply includes supplying the combustion material at a substantially lean mixing ratio when the temperature of the sintered metal fiber sleeve exceeds an operating temperature.

In one embodiment, the supplying includes supplying the burning material at a substantially stoichiometric mixing ratio for a selected period of time.

In one embodiment, the supplying includes supplying the combustion material at a substantially lean mixing ratio immediately after the selected time period expires.

In various embodiments, the radiant burner includes the features of the first aspect.

Further specific and preferred aspects are stated in the accompanying independent technical solutions and subsidiary technical solutions. The features of the subsidiary technical solutions may be combined with the features of the independent technical solutions as appropriate and in different combinations than those explicitly stated in the technical solutions.

In the case where a device feature is described as operable to provide a function, it should be understood that this includes a device feature that provides the function or is adapted or configured to provide the function.

8‧‧‧radiation burner

10‧‧‧ entrance

12‧‧‧ nozzle

14‧‧‧combustion chamber

15‧‧‧Exhaust

16‧‧‧Aperture

18‧‧‧Ceramic top plate

20‧‧‧Porous burner components

21‧‧‧Export surface

22‧‧‧Inflatable volume

23‧‧‧ Entrance surface

24‧‧‧Housing

100‧‧‧Sintered metal fiber sheet

105‧‧‧Outer surface

110‧‧‧Perforated screen

120A‧‧‧Flange

120B‧‧‧Flange

130‧‧‧Ceramic fiber coating

140‧‧‧thermocouple

An embodiment of the present invention will now be further described with reference to the accompanying drawings, in which: FIG. 1 shows a radiant burner according to an embodiment; and FIG. 2 shows the configuration of the porous burner liner shown in FIG. 1 in more detail.

Before making any more detailed discussion of the embodiments, an overview will first be provided. The embodiment provides a radiant burner, which is particularly suitable for operation in a so-called "green mode", in the case where the burner is extinguished during a period of inactivity of the program tool (eg, during an idle step), etc. The cycle may be frequent and have a short duration. The radiant burner liner has a sintered metal fiber sleeve surrounded by an insulating sleeve instead of a typical ceramic radiant burner liner. The combination of the sintered metal fiber sleeve and the insulating sleeve provides a radiant burner that can operate under almost the same conditions and has improved efficiency compared to existing burners, yet it is resistant to thermal cycling Shock. In addition, in order to improve the warm-up time of radiant burners at low temperatures, the mixture of burning materials during normal operation can be adjusted to enrich the mixture before returning to lean conditions.

Radiation burner-general configuration and operation

FIG. 1 shows a radiant burner according to an embodiment, which is indicated by 8 as a whole. The radiant burner 8 processes an exhaust gas stream that is usually pumped from a manufacturing process tool (such as a semiconductor or flat panel display process tool) by a vacuum pumping system. This exhaust gas flow is received at the inlet 10. The exhaust gas flow is delivered from the inlet 10 to a nozzle 12 which injects the exhaust gas flow into a cylindrical combustion chamber 14. In this embodiment, the radiant burner 8 includes four inlets 10 arranged circumferentially, each of which delivers an exhaust gas flow pumped from a respective tool by a respective vacuum pumping system. Alternatively, the exhaust gas stream from a single process tool can be separated into a plurality of streams, each of which is delivered to a respective inlet. Each nozzle 12 is positioned within a respective aperture 16 formed in a ceramic top plate 18 defining an upper surface or inlet surface of the combustion chamber 14. The combustion chamber 14 has side walls defined by an outlet surface 21 of a porous burner element 20, which are schematically shown in FIG. 2 and shown in more detail. The burner element 20 is cylindrical and is held in a cylindrical housing 24.

An inflation volume 22 is defined between one of the inlet surfaces of the burner element 20 and the cylindrical housing 24. A mixture of fuel gas (such as natural gas or a hydrocarbon) and air is introduced into the inflation volume 22 via an inlet nozzle. This mixture of fuel gas and air passes from the inlet surface 23 of the burner element to the outlet surface 21 of the burner element for combustion in the combustion chamber 14.

The nominal ratio of the mixture of fuel gas and air is changed to change the nominal temperature in the combustion chamber 14 to a temperature suitable for the exhaust gas stream to be treated. In addition, the rate at which the mixture of fuel gas and air is introduced into the charge volume 22 is adjusted so that the mixture will burn at the outlet surface 21 of the burner element 20 without visible flames. The exhaust port 15 of the combustion chamber 40 is opened to enable combustion products to be output from the radiant burner 8.

Therefore, it can be seen that the exhaust gas received through the inlet 10 and provided by the nozzle 12 to the combustion chamber 14 is combusted in the combustion chamber 14 which is heated by a mixture of fuel gas and air combusted near the outlet surface 21 of the burner element . This combustion causes heating of the chamber 14 and provides combustion products (such as oxygen) to the combustion chamber 14, one of these combustion products typically has a nominal range of 7.5% to 10.5%, which depends on the fuel-air mixture (CH ₄ , C ₃ H ₈ , C ₄ H ₁₀ ) and the surface burning rate of the burner. The heat and combustion products react with the exhaust flow in the combustion chamber 14 to purify the exhaust flow. For example, SiH ₄ and NH ₃ can be provided in the exhaust gas stream, which react with O _{2 in the} combustion chamber to generate SiO ₂ , N ₂ , H ₂ O, NO _X. Similarly, N ₂ , CH ₄ , C ₂ F ₆ can be provided in the exhaust gas stream, which reacts with O _{2 in the} combustion chamber to generate CO ₂ , HF, H ₂ O.

Porous burner liner configuration

Reference is now made to the configuration of the porous burner liner 20. Its structure is shown in more detail in FIG. 2. In this configuration, the porous burner liner 20 is constructed by rolling and seam welding a sintered metal fiber sheet 100 to a perforated mesh 110, the liner being held between flanges 120A and 120B.

The sintered metal fiber sheet 100 may be any suitable sintered metal fiber, such as SFF1-35 or SFFE-30 supplied by FiberTech of South Korea, or S-mat or D-mat supplied by Micron Fiber-Tech of the United States. Generally, the sintered metal fiber has a porosity of between 80% and 90%, an air permeability of 150 to 300 cc/min/cm ² , and a sheet density of about 694 to 1111 kg/m ³ .

Referring now to Table 1, it has been found that one of the porous burner liners with sintered metal fiber sheets welded to the perforated support 110 operates under the same conditions as the existing ceramic porous burner liners. In this example, a sintered metal fiber sheet having an inner diameter of 152.4 mm (6 inches) times an axial length of 304.8 mm (12 inches) and having a surface area of 145,931 mm ² (226 square inches) (and another example has the following One of the ceramic fiber coatings mentioned is a porous burner liner that uses 36 slm natural gas to burn in 610 slm air, which provides a surface burn rate of about 80 kW/m ² (50,000 BTU/hr/ft ² ) and a rate of 9% A residual oxygen concentration (as measured in the absence of exhaust gas flow). Combustion emissions are measured under simulated exhaust gas flow in the presence of 200 l/min nitrogen. As can be seen, when the exhaust gas stream is subsequently introduced, the combustion emissions (sintered metal sheet/sintered metal fiber sheet + ceramic fiber cladding) are better than existing burners (ceramics).

However, the warm-up time of this configuration at low temperature may be about 15 minutes, which is achieved by igniting under stoichiometric conditions before returning to a lean condition after a short period (for example, such as 10 seconds) Reduced to less than 10 seconds.

In addition, the steady-state temperature of the outer surface 105 of the sintered metal fiber sheet 100 is higher than the steady-state temperature of the outer surface of a ceramic porous burner liner (compared to less than 50°C, which is higher than 120 to 140°C). This temperature rise is much slower than that of the combustion chamber 14 and it is impossible to directly control the start of abundance using this parameter at the same time, and the temperature of the outer surface 105 can be advantageously used to suppress the start of abundance function.

Construct a three-component structure that includes a mechanical outer support (for example, such as the perforated mesh panel 100 and flanges 120A, 120B), a breathable ceramic fiber coating 130, and a sintered metal fiber sheet 100 This results in improved performance, as shown in Table 2 and Table 3. In this example, a sintered metal fiber sheet with an inner diameter of 152.4 mm (6 inches), an axial length of 152.4 mm (6 inches), and a surface area of 72,965 mm ² (113 square inches) welded to the perforated support (And another example has a ceramic fiber coating) The porous burner liner is burned in 310 slm air using 19 slm natural gas, which provides a residual oxygen concentration of 9% (as measured in the absence of exhaust gas flow). The reduction of nitrogen trifluoride was measured in the part of the simulated exhaust gas flow with 200 l/min nitrogen. As can be seen, the combustion emissions (bare metal/insulated metal) are better than the existing ceramic burners when the exhaust gas stream is subsequently introduced.

Table 2

The ceramic fiber coating 130 is selected to have a minimum pressure drop when the surface flow rate is equal to the surface combustion rate described above. Commercially available coating materials, usually between about 6 mm and 12 mm, and preferably 10 mm, such as Isofrac 1260 (calcium silicate) or Saffil (alumina) with a density of 128 kg/m ^{3 in} the pressure drop range of 40 to 60 Pa , Under the head-on speed of 0.1m/s, it has an acceptable performance under the linear pressure-flow rate relationship. Both materials are available from Unifrax Co., Ltd.

As shown in FIG. 2, a thermocouple 140 is provided, which is thermally coupled to the outer surface 105 of the sintered metal fiber sheet 100. The thermocouple 140 or other temperature sensor measures the temperature of the sintered metal fiber sheet 100. When the thermocouple 140 indicates that the temperature of the sintered metal fiber sheet 100 is below a threshold (which indicates that the operating temperature of the combustion chamber 14 is lower than the operating temperature), the fuel to air ratio is increased. When the temperature reported by thermocouple 140 exceeds this threshold (which indicates that the operating temperature of combustion chamber 14 exceeds the operating temperature), the fuel to air ratio is reduced.

It should be understood that although in this embodiment, a perforated mesh 110 and metal flanges 120A, 120B are used to provide mechanical support, other configurations for holding the sintered metal fiber sheet 100 and ceramic fiber coating 130 may be provided .

Although not shown in FIG. 2, the circumferential pleats may be provided in the sintered metal fiber sheet 100 to accommodate the change in length of the sintered metal fiber sheet 100 at different temperatures.

Although the illustrative embodiments of the present invention have been disclosed in detail herein with reference to the accompanying drawings, it should be understood that the present invention is not limited to the exact embodiments and that familiarity with this technology can be made without departing from the scope of the accompanying patent application and its equivalent Various changes and modifications can be realized in the context of the scope of the invention as defined by the object.

14‧‧‧combustion chamber

20‧‧‧Porous burner components

21‧‧‧Export surface

23‧‧‧ Entrance surface

100‧‧‧Sintered metal fiber sheet

105‧‧‧Outer surface

120A‧‧‧Flange

120B‧‧‧Flange

130‧‧‧Ceramic fiber coating

140‧‧‧thermocouple

Claims (13)

A radiant burner for treating a waste gas stream from a manufacturing process tool, the radiant burner includes: a sintered metal fiber sleeve through which combustion materials pass to burn in one of the sintered metal fiber sleeves Burning at the surface; and an insulating sleeve that surrounds the sintered metal fiber sleeve and the burning materials pass through the insulating sleeve. The radiant burner of claim 1, wherein the sintered metal fiber sleeve has at least one of the following items: a porosity of 80% to 90%, a gas permeability of 150 to 300 cc/min/cm ² and 690 to 1110kg / m ³ density one. The radiant burner according to claim 1 or 2, wherein the insulating sleeve is a ceramic fiber coating. The radiant burner according to claim 1 or 2, wherein the insulating sleeve has at least one of the following items: a density of 100 to 150 Kg/m ³ and a pressure drop of 40 to 60 Pa as the combustion materials pass therethrough One density. The radiant burner according to claim 1 or 2, wherein the sintered metal fiber sleeve is held coaxially in the insulating sleeve. The radiant burner of claim 1 or 2, which includes a support operable to hold the sintered metal fiber sleeve and the insulating sleeve. The radiant burner according to claim 1 or 2, wherein the insulating sleeve is held coaxially in the support. The radiant burner according to claim 1 or 2, wherein the sintered metal fiber sleeve includes a circumferentially extending pleat. The radiant burner of claim 1 or 2 including a temperature sensor thermally coupled to the sintered metal fiber sleeve and operable to provide the sintered One of the temperature indications of one of the metal fiber sleeves. The radiant burner of claim 1 or 2, wherein the temperature sensor and the sintered metal fiber sleeve are thermally coupled to an outer surface. The radiant burner of claim 10, which includes a source operable to supply the combustion materials with one of a plurality of mixing ratios selected in response to the temperature. The radiant burner of claim 11, wherein the source is operable to supply the combustion materials at a substantially stoichiometric mixing ratio when the temperature of the sintered metal fiber sleeve fails to exceed an operating temperature. The radiant burner of claim 11, wherein the source is operable to supply the combustion materials at a substantially lean mixing ratio when the temperature of the sintered metal fiber sleeve exceeds an operating temperature.

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