TW201623880A - 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

Radiant burner

The present invention relates to a radiant burner and method.

Radiation burners are known to us and are commonly used to treat exhaust gas streams from one of the manufacturing process tools used in, for example, the semiconductor or flat panel display manufacturing industry. During this manufacturing, residual perfluorocompound (PFC) and other compounds are present in the exhaust stream pumped from the process tool. It is not desirable for PFC to be difficult to remove from the exhaust gas and release it to the environment because it is known to have a relatively high greenhouse effect.

Known radiant burners use combustion to remove PFC and other compounds from the exhaust stream. Typically, the offgas stream is a stream of nitrogen containing one of PFC and other compounds. A fuel gas is mixed with the exhaust stream and the gas stream 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 exit surface, wherein the amount of air passing through the porous burner is not only sufficient to consume fuel gas supplied to the burner but also consumes injection into the combustion chamber All combustibles in the gas stream mixture.

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

According to a first aspect, a radiant burner for processing an exhaust stream from a manufacturing process tool is provided. The radiant burner comprises: a sintered metal fiber sleeve a tube through which the combustion material is combusted to be combusted in a combustion surface adjacent one of the sintered metal fiber sleeves; and an insulating sleeve surrounding the sintered metal fiber sleeve and the combustion material passing through the insulating sleeve.

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

Therefore, a radiant burner can be provided. The radiant burner can process or reduce one of the exhaust streams discharged or discharged from a manufacturing process tool. The radiant burner can include a metal fiber sleeve that can be sintered through which the combustion material can be combusted at a combustion surface proximate or adjacent one of the metal fiber sleeves. The radiant burner can also include an insulative sleeve that can surround or at least partially surround the metal fiber sleeve. The combustion material can also pass through an insulating sleeve to reach the metal fiber casing. In this way, a radiant burner is provided which does not rupture due to the rapid cycling caused by frequent idle steps during its extinction. In addition, by providing an insulating sleeve, the temperature within the radiant burner and the temperature of the outer surface of one of the radiant burners remain comparable to existing ceramic burners. This allows the radiant burner to replace the existing ceramic burner as a field replaceable unit that does not suffer from cracking during such frequent and short duration periods of inoperative tool inactivity.

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

In one embodiment, the sintered metal fiber sleeve has a gas permeability of from 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 from 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 combustion material passes therethrough.

In one embodiment, the sintered metal fiber sleeve is coaxially retained 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 an embodiment, the insulating sleeve is coaxially retained within the support.

In one embodiment, the sintered metal fiber sleeve includes a pleat extending circumferentially. Providing a pleat helps to accommodate variations in the size of the sintered metal casing at different temperatures.

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

In one embodiment, the temperature sensor is thermally coupled to the sintered metal fiber sleeve to an outer surface. Thus, a temperature sensor can be provided outside of the combustion chamber defined by the metal fiber sleeve to protect the temperature sensor from the effects of material within the combustion chamber.

In one embodiment, the radiant burner includes a source operable to supply combustion material in response to one of a plurality of mixing ratios selected for temperature. Thus, the mixing ratio of the combustion materials can be responsive 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 cannula fails to exceed an operating temperature. Therefore, a stoichiometric or flammable gas can be provided for improving the warm-up time of the radiant burner Rich mix ratio.

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

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

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

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

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

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

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

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

8‧‧‧radiation burner

10‧‧‧ entrance

12‧‧‧ nozzle

14‧‧‧ combustion chamber

15‧‧‧Exhaust port

16‧‧‧Aperture

18‧‧‧Ceramic top plate

20‧‧‧Porous burner components

21‧‧‧Exit surface

22‧‧‧Inflated volume

23‧‧‧ entrance surface

24‧‧‧ Shell

100‧‧‧Sintered metal fiber sheet

105‧‧‧Outer surface

110‧‧‧Perforated stencil

120A‧‧‧Flange

120B‧‧‧Flange

130‧‧‧Ceramic fiber coating

140‧‧‧ thermocouple

Embodiments of the invention will now be further described with reference to the accompanying drawings in which: 1 depicts a radiant burner in accordance with an embodiment; and FIG. 2 illustrates the configuration of the porous combustor liner of FIG. 1 in greater detail.

Before any more detailed discussion of the embodiments, an overview will first be provided. Embodiments provide a radiant burner that is particularly adapted to operate in a so-called "green mode" where the burner is extinguished during a program tool inactivity period (eg, during an idle step) Cycles can be frequent and have short durations. The radiant burner liner has a sintered metal fiber sleeve that is 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 nearly identical conditions and has improved efficiency compared to existing burners, yet it is resistant to thermal cycling The vibration. Furthermore, in order to improve the warm-up time of the radiant burner at low temperatures, the mixture of combustion materials during normal operation can be adjusted to make the mixture rich before reverting to a poor condition.

Radiant burners - general configuration and operation

1 depicts a radiant burner, generally indicated at 8, in accordance with an embodiment. The radiant burner 8 processes one of the exhaust streams typically pumped from a manufacturing process tool, such as a semiconductor or flat panel display program tool, by a vacuum pumping system. This exhaust stream is received at the inlet 10. The exhaust stream is delivered from inlet 10 to a nozzle 12 which injects a flow of exhaust gas into a cylindrical combustion chamber 14. In this embodiment, the radiant burner 8 includes four inlets 10 arranged circumferentially, each of which delivers one of the exhaust streams from a respective tool pumped by a respective vacuum pumping system. Alternatively, the exhaust stream from a single program 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 one of the upper or inlet surfaces 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 shown schematically in Figure 2 and shown in more detail. The burner element 20 is cylindrical and held within a cylindrical outer casing 24.

An inflation volume 22 is defined between an inlet surface of one of the burner elements 20 and the cylindrical outer casing 24. A mixture of fuel gas (such as natural gas or a hydrocarbon) and air is introduced into the plenum 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 within the combustion chamber 14.

The nominal ratio of the mixture of fuel gas to air is varied to vary the nominal temperature within the combustor 14 to a temperature suitable for the exhaust stream to be treated. In addition, the rate at which the mixture of fuel gas and air is introduced to the plenum 22 is adjusted such that the mixture will burn at the exit surface 21 of the combustor element 20 without visible flame. The exhaust port 15 of the combustion chamber 40 is opened to enable combustion products to be output from the radiant burner 8.

Accordingly, it can be seen that the exhaust gas received through the inlet 10 and supplied to the combustion chamber 14 by the nozzle 12 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 causes combustion of the heating chamber 14 and provides combustion products (such as oxygen) to the combustion chamber 14, the combustion products of one of these nominal range is generally from 7.5 to 10.5%, depending 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 stream within the combustor 14 to purify the exhaust stream. For example, it may be provided within the exhaust gas flow SiH ₄ and NH _3, which is like the reaction of O ₂ in the combustion chamber to produce _{SiO 2, N 2, H 2} O, NO X. Similarly, N ₂ , CH ₄ , C ₂ F ₆ may be provided within the exhaust stream, which react with O _{2 in the} combustion chamber to produce CO ₂ , HF, H ₂ O.

Porous burner liner configuration

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

The sintered metal fiber sheet 100 can be any suitable sintered metal fiber, such as SFF1-35 or SFFE-30 supplied by South Korea FiberTech, or S-mat or D-mat supplied by Micron Fiber-Tech, USA. Typically, the sintered metal fiber has a porosity between 80% and 90%, a gas 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 a porous burner liner having a sintered metal fiber sheet welded to the perforated support member 110 operates under the same conditions as the existing ceramic porous burner liner. In this example, an inner diameter of 152.4 mm (6 inches) is multiplied by an axial length of 304.8 mm (12 inches) and has a surface area of 145,931 mm ² (226 square inches) of sintered metal fiber sheet (and another example has the following A porous burner liner, referred to as one of the ceramic fiber coatings, is burned in 36 slm of air using 36 slm of natural gas, which provides a surface burn rate of about 80 kW/m ² (50,000 BTU/hr/ft ² ) and 9% A residual oxygen concentration (as measured in the absence of exhaust gas flow). Combustion emissions were measured in a simulated exhaust stream with 200 l/min of nitrogen. As can be seen, when the exhaust stream is subsequently introduced, the combustion effluent (sintered metal sheet/sintered metal fiber sheet + ceramic fiber coating) is better than the existing burner (ceramic).

However, the warm-up time of this configuration at low temperatures can be about 15 minutes, which is ignited under stoichiometric conditions before restoring to a poor condition after a short period (for example, 10 seconds). Shortened 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, higher) 120 to 140 ° C). This temperature rise is much slower than the combustion chamber 14 and it is not possible to use this parameter at the same time to directly control the rich start. The temperature of the outer surface 105 can advantageously be used to inhibit the priming function of the rich.

A three-part structure is constructed that includes a mechanical outer support (for example, the perforated mesh 100 and flanges 120A, 120B), a gas permeable ceramic fiber coating 130, and a sintered metal fiber sheet 100. This results in improved performance as shown in Tables 2 and 3. In this example, a sintered metal fiber sheet having 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. A porous burner liner (and another example having a ceramic fiber coating) was burned in 310 slm of air using 19 slm of natural gas, which provided one of 9% residual oxygen concentration (as measured in the absence of exhaust gas flow). The reduction of nitrogen trifluoride was measured as part of the exhaust gas stream with a simulated nitrogen of 200 l/min. As can be seen, the combustion emissions (bare metal/insulating metal) are better than the existing ceramic burners when the subsequent exhaust stream is introduced.

Table 2

The ceramic fiber cladding 130 is selected to have a minimum pressure drop when the surface flow rate is equal to the surface burning rate described above. Commercially available cladding materials typically between about 6 mm and 12 mm, and preferably 10 mm, such as Isofrax 1260 (calcium silicate) or Saffil (alumina) having a density of 128 kg/m ³ in the 40 to 60 Pa pressure drop range At an on-speed of 0.1 m/s, it has acceptable performance with a linear pressure-flow rate relationship. Both materials are available from Unifrax Limited.

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

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

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

Although the present invention has been described with reference to the preferred embodiments of the present invention, it is understood that the invention is not to be construed as Various changes and modifications can be made without departing from the scope of the invention.

14‧‧‧ combustion chamber

20‧‧‧Porous burner components

21‧‧‧Exit surface

23‧‧‧ entrance surface

100‧‧‧Sintered metal fiber sheet

105‧‧‧Outer surface

120A‧‧‧Flange

120B‧‧‧Flange

130‧‧‧Ceramic fiber coating

140‧‧‧ thermocouple

Claims (18)

A radiant burner for treating an exhaust stream from a manufacturing process tool, the radiant burner comprising: a sintered metal fiber sleeve through which a combustion material passes to burn in one of the sintered metal fiber sleeves Burning at the surface; and an insulating sleeve surrounding the sintered metal fiber sleeve and the combustion material passing through the insulating sleeve. The radiant burner of claim 1, wherein the sintered metal fiber sleeve has at least one of: 80% to 90% of one porosity, 150 to 300 cc/min/cm ² of one of air permeability, and 690 to One density of 1110 kg/m ³ . The radiant burner of claim 1 or 2, wherein the insulating sleeve is a ceramic fiber coating. The radiant burner of claim 1 or 2, wherein the insulating sleeve has at least one of: a density of one of 100 to 150 Kg/m ³ and a pressure drop of 40 to 60 Pa is provided with the combustion material passing therethrough One of the densities. The radiant burner of claim 1 or 2, wherein the sintered metal fiber sleeve is coaxially retained within the insulating sleeve. A radiant burner of claim 1 or 2, comprising a support operable to hold the sintered metal fiber sleeve and the insulating sleeve. The radiant burner of claim 1 or 2, wherein the insulating sleeve is coaxially retained within the support. The radiant burner of claim 1 or 2, wherein the sintered metal fiber sleeve comprises a pleat extending circumferentially. A radiant burner according to claim 1 or 2, comprising a temperature sensor thermally coupled to the sintered metal fiber sleeve and operable to provide the sintered One of the temperatures of one of the metal fiber sleeves is indicated. The radiant burner of claim 1 or 2, wherein the temperature sensor is thermally coupled to the sintered metal fiber sleeve to an outer surface. The radiant burner of claim 10, comprising a source operable to supply the combustion materials in response to 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 casing 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 casing exceeds an operating temperature. A method of operating a radiant burner for treating an exhaust stream from a manufacturing process tool, the method comprising: determining a temperature of one of an outer surface of one of the radiant metal fiber sleeves through which the combustion material passes The sintered metal fiber sleeve is combusted at a burning surface proximate to one of the sintered metal fiber sleeves; and the combustion material is supplied in response to one of a plurality of mixing ratios selected in response to the temperature. The method of claim 14, wherein the supplying comprises supplying the combustion materials at a substantially stoichiometric mixing ratio when the temperature of the sintered metal fiber cannula fails to exceed an operating temperature. The method of claim 14 or 15, wherein the supplying comprises supplying the combustion materials at a substantially lean mixing ratio when the temperature of the sintered metal fiber sleeve exceeds an operating temperature. The method of any one of claims 14 or 15, wherein the supplying comprises supplying the combustion materials at the substantially stoichiometric mixing ratio for a selected period of time. The method of any one of claims 14 or 15, wherein the supplying comprises immediately supplying the combustion materials at the substantially lean mixing ratio after a timeout of the selected time period.