Gas nozzle cleaning method and system

Abstract

A system and method for cleaning gas flowing through an inlet nozzle of a combustion chamber of an abatement burner. The abatement burner intermittently receives gas for combustion from a feed process. The nozzle includes a cleaning mechanism including a movable cleaning member for physically removing unwanted deposits from the nozzle. The cleaning member is movable from a first, retracted position in which the cleaning member is out of the path of a flame associated with the nozzle to a second, cleaning position in which the cleaning member is in the path of the flame associated with the nozzle. The method includes the steps of: a. identifying when the nozzle is out of use; b. moving the cleaning member from the first position to the second position when the nozzle is out of use; and c. returning the cleaning member to the first position prior to use of the nozzle.

Description

Technical Field

[0001] This invention relates to a cleaning system for a gas emission reduction system, a gas emission reduction burner, and a method for cleaning the gas inlet nozzle of the emission reduction burner. Background Technology

[0002] Emission reduction burners are used to treat exhaust gases from processes such as semiconductor manufacturing. This treatment is important because the exhaust gases can be toxic and / or harmful to the atmosphere due to their high greenhouse effect.

[0003] One such exhaust gas treatment method involves combustion to remove harmful compounds from the gas stream. Typically, exhaust gas is mixed with fuel gas, which is then conveyed via an inlet assembly to a combustion chamber for combustion. The inlet assembly typically includes a nozzle structure through which the gas mixture is conveyed. The gas mixture is combusted as it exits the nozzle structure.

[0004] Inlet components typically also include a cleaning mechanism for removing solid deposits of process gases that form on the nozzle structure due to exhaust gas combustion. This cleaning mechanism can be, for example, a retractable cleaning spring designed to physically remove deposits from the nozzle structure. However, it has been found that deposits still form on both the nozzle structure and the cleaning mechanism itself despite the presence of such a mechanism. The impact of these deposits is that they reduce the lifespan and / or functionality of the nozzle structure and cleaning mechanism, decrease the efficiency of the gas emission reduction system, and increase machine downtime during repair and replacement of these components.

[0005] In existing cleaning methods, the operation of the cleaning element results in it being placed in the flame path. It has been found that deposits, such as alumina, can form on the distal end of the nozzle even when the cleaning element is in use. This can lead to nozzle confinement, and / or backfire within the nozzle, and / or reduced nozzle conductivity, and / or flame deformation, which in turn can result in incomplete combustion and the unwanted generation of hydrocarbons and carbon monoxide.

[0006] Furthermore, such deposits have been found to form on the cleaning components themselves, particularly at the distal end within the flame. Additionally, damage to the cleaning components themselves has been observed during use of the cleaning mechanism. The cleaning components have cracked, sometimes to the point of complete breakage, hindering them from achieving their intended purpose.

[0007] Unwilling to be bound by theory, the inventors have discovered that during the nozzle cleaning process, the cleaning component passing through the flame associated with the nozzle promotes the aforementioned deposition and cracking. Through repeated insertion and retraction from the flame, the cleaning component undergoes repeated heating and cooling cycles. Cracks in the cleaning component may be due to the introduction and propagation of microcracks resulting from multiple heating cycles and subsequent rapid cooling. Therefore, it is desirable to provide an improved nozzle cleaning system and method that avoids these problems. Summary of the Invention

[0008] Therefore, in a first aspect, a method is provided for cleaning a gas inlet nozzle of a combustion chamber of an emission-reducing burner. The emission-reducing burner may intermittently receive gas for combustion from a supply process. The nozzle may include a cleaning mechanism comprising a movable cleaning member for physically removing unwanted deposits from the nozzle. The cleaning member is movable from a retracted first position to a second position (cleaning position), in which the cleaning member is located outside the path of the nozzle flame associated with the nozzle, and in the second position, the cleaning member is located within the path of the nozzle flame. The method includes the steps of: identifying when the nozzle flame is closed; moving the cleaning member from the first position to the second position when the nozzle flame is closed; and returning the cleaning member to the first position before the nozzle flame is turned on (e.g., ignited). If unwanted deposits are present, the movement of the cleaning member from the retracted first position to the second cleaning position may physically remove the unwanted deposits from the nozzle.

[0009] For the purposes of this invention, the nozzle flame path refers to the volume defined by the maximum volume occupied by the nozzle flame during nozzle use, i.e., during combustion. It should be understood that, depending on whether the nozzle flame is on or off, the nozzle flame path may or may not actually contain the flame. Typically, when the nozzle flame is on, the cleaning member does not pass through the end of the nozzle. Additionally or alternatively, when the nozzle outlet temperature is above about 1000°C, the cleaning member does not enter the nozzle flame path. Preferably, when the nozzle outlet temperature is below about 1000°C, preferably below 600°C, and preferably at ambient temperature (e.g., room temperature), the cleaning member may only be in the first position.

[0010] Emission reduction burners may include radiant burners. Typically, radiant burners may include inward-burning radiant burners, preferably substantially tubular burners. Typically, in use, gases from the supply process flow into the burner through nozzles, where they undergo heating and additional chemical processes such as combustion, oxidation, or reduction. Preferably, these reactions can occur in a substantially laminar flow region away from the burner walls to prevent oxide deposition thereon.

[0011] Emission reduction burners can have multiple operating modes, each providing specific nozzle conditions, and in particular specific nozzle outlet temperatures. Typically, emission reduction burners can have four operating modes.

[0012] In the first mode, the emission reduction burner is off. Typically, when the emission reduction burner is off, there is no process gas flow (i.e., the gas supplied to the process for combustion), any ignition burner is off, any radiant burner is off, and the nozzle flame is off. Typically, the temperature at the nozzle outlet is at essentially ambient temperature, such as essentially room temperature (approximately 20°C).

[0013] In the second mode, the emission reduction burners are in an idle mode. Typically, the idle mode is characterized by no process gas flow, any ignition burners are on, any radiant burners are off, and the nozzle flame is off. In the idle mode, the nozzle outlet temperature is typically at essentially ambient temperature, such as essentially room temperature (approximately 20°C).

[0014] In the third mode, the emission reduction burner is in radiant burner mode. Typically, radiant burner mode is characterized by the process gas flow entering the combustion chamber through nozzles, any ignition burner turning on, the radiant burner turning on, and the nozzle flame turning off. In radiant burner mode, the nozzle outlet temperature is typically from about 600°C to about 1000°C.

[0015] In the fourth mode, the emission reduction burner can be in flame mode. Flame mode is characterized by the process gas flow entering the combustion chamber via a nozzle, with any ignition burner activated, any radiant burner activated, and a nozzle flame activated. In flame mode, the nozzle outlet temperature is typically from about 1000°C to about 1800°C. Typically, fuels such as methane (e.g., natural gas), propane, or butane (e.g., liquefied petroleum gas) or hydrogen are added to the process gas and ignited in the presence of an oxidizer (e.g., oxygen or CDA) to form a nozzle flame. The fuel can include methane, such as natural gas.

[0016] Typically, when the emission-reducing burner is off or in idle mode, the cleaning component can move from the first position to the second position. Additionally, before the emission-reducing burner is in flame mode, the cleaning component can move back to the first position. Alternatively or additionally, when the emission-reducing burner is in radiant burner mode, the cleaning component can be in either the first or second position.

[0017] During the use of the emission reduction burner, one or more nozzle flames and / or radiant burners can be opened and closed intermittently. It has been found that by associating the movement of the cleaning mechanism with the operation of the nozzle flame, such that the cleaning component does not enter the path of the nozzle flame when it is open, the amount of deposits and breakage on the nozzle and / or cleaning component can be significantly reduced. Preferably, the cleaning component does not enter the path of the nozzle flame when it is open.

[0018] Advantageously, this reduces the amount of maintenance required for cleaning components and / or nozzles, and minimizes machine downtime. Furthermore, it extends the lifespan of components.

[0019] By preventing the cleaning components from entering the nozzle flame path when the nozzle flame is on, the nozzle cleaning mechanism will operate more efficiently, thereby allowing for an increase in the mean time between failures.

[0020] Typically, the first position may include virtually all cleaning components located outside the path of the nozzle flame.

[0021] In another aspect, the present invention provides a method for cleaning the gas inlet nozzle of a combustion chamber of an emission-reducing burner. The emission-reducing burner may intermittently receive gas from a supply process for combustion. The nozzle may include a cleaning mechanism comprising a movable cleaning member for physically removing unwanted deposits from the nozzle. Typically, the cleaning member can be moved from a retracted first position to a second cleaning position, in which the cleaning member is located outside the path of the nozzle flame associated with the nozzle, and in the second cleaning position, in which the cleaning member is located within the path of the nozzle flame associated with the nozzle.

[0022] The method includes the following steps: identifying a step in the supply process when gas from the supply process is provided to the emission reduction system for combustion; and guiding the movement of the cleaning component to ensure that the cleaning component is in a first position during the identified step, preferably for the duration of the identified step. By preventing the operation of the cleaning mechanism during the identified step in the supply process, the cleaning component remains away from the nozzle flame at that time. When gas is provided to the emission reduction system for combustion, by synchronizing the operation of the cleaning mechanism with a specific step in the supply process, the accumulation of deposits on both the cleaning mechanism and the nozzle, as well as the breakage and wear of the cleaning component, can be reduced. Advantageously, this can increase the mean time between failures and increase the overall efficiency of the gas emission reduction process.

[0023] During the method described, when the cleaning component retracts to the first position, material may still be deposited on the nozzle, but this will be removed through proper operation of the cleaning mechanism. Therefore, the present invention ensures that the cleaning mechanism itself is more effective.

[0024] In addition, the content of the gas from the supply process may vary, and the method may further include the following steps: identifying a step in the supply process when a specific gaseous chemical is supplied to the emission reduction system for combustion; and guiding the movement of the cleaning component to ensure that the cleaning component is in a first position for the duration of the identified step.

[0025] Certain gaseous chemicals may be particularly harmful to the operation of the cleaning mechanism due to factors such as increased combustion temperature and / or increased deposition rate and / or more corrosive chemicals. Advantageously, step (b) as described above ensures that the cleaning mechanism is not damaged by said specific gaseous chemicals. Specifically, harmful gaseous chemicals may include, for example, volatile aluminum chloride mixed with organic residues, which may be derived from an aluminum etching formulation. This material can be coated on the cleaning spring such that if the cleaning spring is moved into the flame, the aluminum compound can react rapidly to form alumina. The alumina can coat the cleaning spring to form a substantially immovable deposit layer. Over time, these deposits can accumulate to form a solid blockage that can clog the nozzle.

[0026] Additionally, the method may include identifying all such steps in the supply process and guiding the movement of the cleaning component to ensure that the cleaning component is in the first position for the duration of all identified steps.

[0027] Typically, the method may further include the step of moving the cleaning component to a second position when the nozzle flame is no longer in use. In this case, "no longer in use" means that no combustion is occurring at this time. Preferably, the method may further include the step of circulating the cleaning component to the second position when the nozzle flame is turned off or when both the radiant burner and the nozzle flame are turned off.

[0028] Preferably, the second position includes the distal end of the cleaning member reaching the distal end of the nozzle. Advantageously, by ensuring that the cleaning member moves to the second position when the nozzle flame is no longer in use, any deposit buildup formed on the nozzle when the cleaning member is in the first position can be removed. The more regularly deposits are removed from the nozzle, the less likely the overall performance of the emission-reducing burner will be affected.

[0029] Typically, the method may further include a step of returning the cleaning component to the first position before one of the identified steps occurs and / or before the nozzle flame is reused. This ensures that the cleaning component remains in the first position whenever it might be susceptible to increased deposits and / or damage as described above. Advantageously, this increases the average time between efficiency and failure.

[0030] On the other hand, a cleaning system is provided for a gas inlet nozzle of a combustion chamber in an emission reduction system. The emission reduction system can intermittently receive exhaust gas for combustion from a supply process. The cleaning system may include a cleaning mechanism associated with the nozzle, the cleaning mechanism including a movable cleaning member for removing unwanted deposits from the nozzle. The cleaning member is movable from a first position to a second position, in the first position being outside the flame path associated with the nozzle, and in the second position being within the flame path associated with the nozzle. The system may be configured to coordinate the movement of the cleaning member such that the cleaning member is in the first position before and during the supply of exhaust gas to the nozzle for combustion via the supply process.

[0031] As previously described, it has been found that by associating the movement of the cleaning mechanism with the supply of exhaust gas, and thus with the presence of a flame, so that the cleaning component does not enter the path of the flame during combustion, the amount of deposits and breakage on the cleaning component can be significantly reduced. Advantageously, this reduces the amount of maintenance required for the cleaning mechanism and nozzles, and minimizes machine downtime. Furthermore, it extends the lifespan of components.

[0032] By preventing the cleaning component from entering the flame path during the flame's presence, the nozzle cleaning mechanism will operate more efficiently, thereby allowing for improved mean time between failures. Preferably, the cleaning component can be further prevented from entering the flame path during the radiant burner's on-time.

[0033] During use, deposits may still accumulate on the inside of the nozzle, but this can be removed by using the cleaning mechanism correctly.

[0034] Typically, the coordinated movement of the cleaning components in a cleaning system can be automated. Advantageously, this improves the efficiency of the cleaning system, and thus the efficiency of the emissions reduction system.

[0035] On the other hand, a gas emission reduction burner including a combustion chamber may be provided, wherein the combustion chamber may include a gas inlet nozzle and a cleaning system as described herein.

[0036] Preferably, the gas emission reduction burner can be an Atlas Etch system or an Atlas ULF system.

[0037] Typically, a gas emission reduction burner may include multiple gas inlet nozzles, each with its associated separate cleaning system. Preferably, the gas emission reduction burner may include at least one gas inlet nozzle, more preferably at least four gas inlet nozzles, and even more preferably up to about ten gas inlet nozzles, such as six gas inlet nozzles.

[0038] Advantageously, having a separate cleaning system associated with each of the plurality of gas inlet nozzles ensures that each gas inlet nozzle remains free of deposit buildup, thereby improving the overall efficiency of the gas emission reduction burner.

[0039] Typically, each cleaning system can be coordinated independently with its associated external process. Such external processes can include, for example, etching or chemical vapor deposition processes used in the semiconductor industry. This is advantageous compared to operating all cleaning systems simultaneously and / or according to timers, as it ensures that each cleaning system operates only at its optimal time relative to its associated external process. This ensures that excessive deposit buildup on each gas inlet nozzle is prevented during use. Benefically, this allows for improved efficiency of the gas emission reduction burner while also allowing for an increased mean time between failures. Furthermore, it allows each inlet nozzle and cleaning system to operate independently and maintain efficient operation.

[0040] On the other hand, methods or systems as described herein are provided, wherein the cleaning component may be a helical cleaning spring. Preferably, the helical spring may be coupled to an actuator that provides reciprocating displacement of the helical spring in the axial direction of the nozzle between first and second positions to clean any deposits formed on the nozzle structure.

[0041] To avoid any doubt, all aspects described above can be combined with necessary modifications. Attached Figure Description

[0042] Figure 1 shows a nozzle with a short cleaning spring, along with the accompanying nozzle.

[0043] Figure 2 shows nozzle deposits as seen in existing cleaning systems.

[0044] Figure 3 shows nozzle deposits as seen in other cleaning systems in the prior art.

[0045] Figure 4 The cleaning mechanism of the present invention is shown. Detailed Implementation

[0046] Figure 1 shows a nozzle structure (1) and a cleaning member (2) according to the prior art. The nozzle structure (1) has a nozzle (3). The nozzle (3) has a central conduit configured to be placed on the cleaning member (2) such that the nozzle (3) acts as a sleeve surrounding the cleaning member (2).

[0047] The cleaning component (2) includes a substantially helical spring (4). The substantially helical spring (4) may also be referred to as the "cleaning spring". The spray gun (5) is coaxially positioned with the cleaning spring (4) such that the cleaning spring (4) surrounds the spray gun (5). In use, gas travels through the spray gun (5) and exits from the distal end of the spray gun (6) for combustion.

[0048] At the first end, a cleaning spring (4) is coupled to an actuator (not shown) that provides reciprocating displacement of the cleaning spring (4) in the axial direction of the nozzle (3) between the first and second positions. In Figure 1, the cleaning spring (4) is shown in the second position, where it extends beyond the distal end of the spray gun (6). In the first position (not shown), the cleaning spring (4) is retracted by the actuator such that it does not extend beyond the distal end of the spray gun (6).

[0049] As can be seen, the distal end of the nozzle (3) has deposits (7) accumulated in the central conduit. The accumulation of deposits (7) has caused the size of the orifice (8) through which the gas can exit the nozzle (3) to become smaller and irregular in shape. This can lead to a decrease in the efficiency of the gas emission reduction system. If the nozzle (3) is blocked by deposits (7), backburning may occur inside the nozzle (3), which may cause the nozzle to deform or be damaged. The accumulation of deposits (7) on the nozzle may also reduce the conductivity of the nozzle (3). The accumulation of deposits (7) may also cause deformation of the nozzle flame (not shown), which can lead to incomplete combustion of process gases and the generation of unwanted hydrocarbons and / or carbon monoxide.

[0050] The cleaning spring (4) shown is a “short” cleaning spring. This means that its length is less than about 50 mm. As shown, there is no buildup of deposits (7) on the “short” cleaning spring (4), but it is no longer able to clean the entire nozzle (3), and thus deposits (7) have accumulated in the central conduit and cannot be removed. This may lead to a decrease in nozzle efficiency and potentially to eventual clogging and failure. In order for the cleaning spring (4) to be able to clean the entire nozzle (3), the helical cleaning spring (4) should generally have sufficient length when in the second position to extend beyond the distal end of the nozzle (3) on the actuator side. Preferably, the helical cleaning spring (4) has sufficient length such that when in the second position, at least one helix of the cleaning spring (4), more preferably at least two helices, extend beyond the distal end of the nozzle (3) on the actuator side. If other cleaning components are used, they may also extend beyond the end of the nozzle when in the second cleaning position.

[0051] Figure 2 illustrates a cleaning spring (4) according to the prior art. As can be seen, deposits (7) have accumulated at the end of the cleaning spring (4). These deposits (7) have formed during the operation of the gas emission reduction system because the cleaning spring (4) is placed in the flame path (not shown). The accumulation of deposits (7) on the cleaning spring (4) will reduce the efficiency of the gas emission reduction system because the deposits (7) will be in the flame path. In addition, it may cause damage to the cleaning spring (4) and reduce the service life of the component.

[0052] As shown in Figure 3, the cleaning spring (4) according to the prior art exhibits a buildup of deposits (7). In this case, the deposits have covered the entire distal end of the cleaning spring (4). This will block the direct path of the flame as it leaves the nozzle (not shown), which may reduce the efficiency of the gas emission reduction system and may also lead to further heating of the cleaning spring (4). Heating of the cleaning spring (4) may lead to further buildup of deposits (7) and may even cause the cleaning spring (4) to crack and fail.

[0053] It can also be seen that there is already accumulated deposit (9) on the edge of the nozzle (3). This may be a further effect of the deposit (7) clogging the end of the cleaning spring (4).

[0054] Figure 4 The illustration shows a cleaning spring (10) according to the invention. As previously described, the cleaning spring (10) has a substantially helical shape and surrounds the spray gun (11). The cleaning spring (10) is configured to be fitted inside a nozzle (not shown) and substantially surrounded by the nozzle.

[0055] During operation of the gas emission reduction system, gas passes through the nozzle (11) and exits from the distal end of the nozzle (12) for combustion. As previously described, the position of the cleaning spring (4) can be moved between a first position and a second position, in which the cleaning spring (10) is located outside the flame path associated with the nozzle, and in the second position, the cleaning spring (10) is located within the flame path associated with the nozzle. The position of the cleaning spring (10) can be configured to be associated with a step in the supply process when gas is supplied for emission reduction in combustion, and / or with a step in the supply process when a particular gaseous chemical is supplied.

[0056] As shown in the figure, by associating the movement of the cleaning spring (10) with process steps or gaseous chemicals, deposits can be prevented from accumulating on the cleaning spring (10) and / or the nozzle. Furthermore, damage to the cleaning spring (10) can be minimized by ensuring that it is not in the flame path associated with the nozzle during combustion. Overall, this results in an increase in the average time between failures.

[0057] It should be understood that various modifications can be made to the illustrated embodiments without departing from the spirit and scope of the invention as defined by the appended claims, as interpreted under patent law.

[0058] Key figure labels

[0059] 1. Nozzle structure (existing technology)

[0060] 2. Cleaning components (existing technology)

[0061] 3. Nozzle

[0062] 4. Basically a helical spring (existing technology)

[0063] 5. Spray gun (existing technology)

[0064] 6. The distal end of the spray gun (existing technology)

[0065] 7. Deposits on springs (existing technology)

[0066] 8. Hole (Prior Art)

[0067] 9. Deposits on the nozzle (Prior art)

[0068] 10. Clean the springs.

[0069] 11. Spray gun

[0070] 12. The far end of the spray gun.

Claims

1. A method for cleaning a gas inlet nozzle of a combustion chamber of an emission-reducing burner, the burner intermittently receiving combustion gas from a supply process, the nozzle including a cleaning mechanism comprising a movable cleaning member for removing unwanted deposits from the nozzle, the cleaning member being movable from a retracted first position to a second cleaning position, in the first position being located outside the flame path associated with the nozzle, and in the second cleaning position being located within the flame path associated with the nozzle; wherein, The content of the gas from the supply process can vary, and the method includes the following steps: a. When specific gaseous chemicals are supplied to an emissions reduction system for combustion, identify the steps in the supply process; and b. Guide the movement of the cleaning component to ensure that the cleaning component is in the first position during the duration of the identified step.

2. The method of claim 1, further comprising the step of moving the cleaning member to the second cleaning position when the nozzle flame is no longer in use.

3. The method according to any one of claims 1 to 2, comprising the step of returning the cleaning component to the first position before the identified step occurs and / or the nozzle flame is reused.

4. The method according to any one of claims 1 to 2, wherein, The cleaning component is a helical cleaning spring.

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