GAS NOZZLE CLEANING METHOD AND SYSTEM

Abstract

A method of cleaning a gas inlet nozzle of an abatement burner combustion chamber. The abatement burner intermittently receives gas for combustion from a feed process. The nozzle comprises a cleaning mechanism including a movable cleaning member for physically removing unwanted deposits from the nozzle. The cleaning member is movable from a retracted first position wherein the cleaning member is outside a path of a flame associated with the nozzle, to a second cleaning position wherein the cleaning member is in a path of the flame associated with the nozzle. The method comprises 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 while the nozzle is out of use; and c. returning the cleaning member to the first position before nozzle is in use.

Claims

1. A method of cleaning a gas inlet nozzle of an abatement burner combustion chamber, the abatement burner intermittently receiving gas for combustion from a feed process, the nozzle comprising a cleaning mechanism including a movable cleaning member for removing unwanted deposits from the nozzle, the cleaning member being movable from a retracted first position wherein the cleaning member is outside a path of a flame associated with the nozzle to a second cleaning position wherein the cleaning member is in a path of the flame associated with the nozzle; the method comprising the steps of: a. identifying when the nozzle flame is off; b. moving the cleaning member from the first position to the second position while the nozzle flame is off; and c. returning the cleaning member to the first position before the nozzle flame is on.

2. A method of cleaning a gas inlet nozzle of an abatement burner combustion chamber, the abatement burner intermittently receiving gas for combustion from a feed process, the nozzle comprising a cleaning mechanism including a movable cleaning member for removing unwanted deposits from the nozzle, the cleaning member being movable from a retracted first position wherein the cleaning member is outside a path of a flame associated with the nozzle to a second cleaning position wherein the cleaning member is in the path of the flame associated with the nozzle; the method comprising the steps of: a. identifying a step in the feed process when gas is provided to the abatement system for combustion; and b. directing the movement of the cleaning member to ensure the cleaning member is in the first position during the identified step, preferably for the duration of the identified step.

3. The method according to claim 2 wherein the content of the gas from a feed process may vary and the method comprises the steps of: a. identifying a step in the feed process when a specific gas chemistry is being provided to the abatement system for combustion; and b. directing the movement of the cleaning member to ensure the cleaning member is in the first position for the duration of the identified step.

4. The method according to claim 2 further comprising identifying all such steps in the feed process and directing the movement of the cleaning member to ensure the cleaning member is in the first position for the duration of all the identified steps.

5. The method according to claim 2 comprising the step of moving the cleaning member to the second position when the nozzle flame is out of use.

6. The method according to claim 2 comprising the step of returning the cleaning member to first position before the occurrence of one of the identified steps and/or the nozzle flame is returned to use.

7. A cleaning system for a gas inlet nozzle of an abatement system combustion chamber, the abatement system intermittently receiving exhaust gas for combustion from a feed process, the cleaning system comprising: a cleaning mechanism associated with the nozzle including a movable cleaning member for removing unwanted deposits from the nozzle, the cleaning member being movable from a first position wherein the cleaning member is outside a path of the flame associated with the nozzle to a second position wherein the cleaning member is in the path of the flame associated with the nozzle; wherein the system is configured to coordinate movement of the cleaning member such that the cleaning member is in the first position before and during the provision of exhaust gas by the feed process to the nozzle for combustion.

8. The cleaning system according to claim 7 wherein the system is configured to coordinate movement of the cleaning member such that the cleaning member is only in the second position when combustion of exhaust gas from the feed process is ceased.

9. The cleaning system according to claim 7 wherein the coordinated movement of the cleaning member is automated.

10. A gas abatement burner comprising a combustion chamber, said combustion chamber comprising a gas inlet nozzle and a cleaning system according to claim 7.

11. The gas abatement burner according to claim 10 comprising a plurality of gas inlet nozzles each having an individual cleaning system associated therewith.

12. The gas abatement burner according to claim 11 wherein each cleaning system is independently coordinated with an external process with which it is associated.

13. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG. 1 shows a nozzle with a short cleaning spring, along with the accompanying nozzle.

[0046] FIG. 2 shows nozzle deposition as seen in a cleaning mechanism of the prior art.

[0047] FIG. 3 shows nozzle deposition as seen in further cleaning mechanism of the prior art.

[0048] FIG. 4 shows a cleaning mechanism of the present invention.

DETAILED DESCRIPTION

[0049] As illustrated in FIG. 1, a nozzle structure (1) and cleaning member (2) according to the prior art are shown. The nozzle structure (1) has a nozzle (3). The nozzle (3) has a central conduit which is configured to be placed over the cleaning member (2) such that the nozzle (3) acts as a sleeve surrounding the cleaning member (2).

[0050] The cleaning member (2) comprises a substantially helical spring (4). The substantially helical spring (4) may also be known as a “cleaning spring”. A lance (5) is positioned coaxially with the cleaning spring (4) such that the cleaning spring (4) surrounds the lance (5). In use, gases travel through the lance (5) and are expelled from a distal end of the lance (6) for combustion.

[0051] At a first end, the cleaning spring (4) is coupled to an actuator (not shown), which provides reciprocal displacement of the cleaning spring (4) in the axial direction of the nozzle (3) between first and second positions. In FIG. 1, the cleaning spring (4) is shown in the second position, wherein it extends beyond the distal end of the lance (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 lance (6).

[0052] As can be seen, the distal end of the nozzle (3) has a build-up of deposit (7) in the central conduit. The deposit (7) build-up has caused the aperture (8) through which gas may leave the nozzle (3) to become reduced in size and to have an irregular shape. This may result in reduced efficiency of the gas abatement system. If the nozzle (3) becomes blocked by deposit (7) then burn-back within the nozzle (3) may occur, which may result in distortion or damage of the nozzle. The deposit (7) build-up on the nozzle may also reduce the conductance of the nozzle (3). Deposit (7) build-up may additionally result in distortion of the nozzle flame (not shown) which can lead to incomplete combustion of the process gases and the production of unwanted hydrocarbons and/or carbon monoxide.

[0053] The cleaning spring (4) shown is a “short” cleaning spring. This means that it is less than about 50 mm in length. As shown, there is no build up of deposit (7) on the “short” cleaning spring (4), but it is no longer capable of cleaning the entire nozzle (3) and accordingly has resulted in a build-up of deposit (7) in the central conduit that could not be cleared. This may result in the reduction of the efficiency of the nozzle, and potentially the eventual blockage and failure. To enable the cleaning spring (4) to clean the entire nozzle (3), when the cleaning spring (4) is in the second position, the helical cleaning spring (4) should typically have sufficient length such that it extends beyond the end of the nozzle (3) distal to the actuator. Preferably, the helical cleaning spring (4) is of sufficient length such that at least one helix, more preferably at least two helixes of the cleaning spring (4) extend beyond the end of the nozzle (3) distal to the actuator when the cleaning spring (4) is in the second position. If other cleaning members are employed they too may extend beyond the end of the nozzle when in the second, cleaning position.

[0054] FIG. 2 illustrates a cleaning spring (4) according to the prior art. As can be seen, at the end of the cleaning spring (4), there has been a build-up of deposit (7). This deposit (7) has formed as a result of the cleaning spring (4) being placed in the path of the flame (not shown) during operation of the gas abatement system. The build up of deposit (7) on the cleaning spring (4) will reduce the efficiency of the gas abatement system as the deposit (7) will be in the path of the flame. Additionally, it may cause damage to the cleaning spring (4) and reduce the life span of the component.

[0055] As illustrated in FIG. 3, a cleaning spring (4) according to the prior art can be seen, wherein the cleaning spring (4) again exhibits a build-up of deposit (7). In this instance, the deposit has covered the entirety of the distal end of the cleaning spring (4). This will block the direct path of the flame as it leaves the lance (not shown), which may reduce the efficiency of the gas abatement system, and may also lead to further heating of the cleaning spring (4). The heating of the cleaning spring (4) may lead to further build-up of deposit (7) and even possibly to cracking and failure of the cleaning spring (4).

[0056] It can also be seen that there has been deposit (9) that has built-up on the edge of the nozzle (3). This may be a further impact of the blockage of the end of the cleaning spring (4) by deposit (7).

[0057] FIG. 4 illustrates a cleaning spring (10) according to the present invention. As described herein previously, the cleaning spring (10) has a substantially helical shape and surrounds the lance (11). The cleaning spring (10) is configured to fit within and be substantially surrounded by a nozzle (not shown).

[0058] During operation of the gas abatement system, gases pass through the lance (11) and are expelled from a distal end of the lance (12) for combustion. As described previously, the position of the cleaning spring (4) is movable between a first position, wherein the cleaning spring (10) is outside the path of the flame associated with the nozzle, and a second position, wherein the cleaning spring (10) is in the path of the flame associated with the nozzle. The position of the cleaning spring (10) may be configured to be associated with a step in a feed process when gas is provided to the abatement for combustion, and/or with a step in the feed process when a specific gas chemistry is being provided.

[0059] As shown, by associating the movement of the cleaning spring (10) with a process step or gas chemistry, the build-up of deposits on the cleaning spring (10) and/or the nozzle can be prevented. Also, by ensuring that the cleaning spring (10) is not in the path of the flame associated with the nozzle during combustion, damage to the cleaning spring (10) can be minimised. Overall this results in an increased mean time between failures.

[0060] It will be appreciated that various modifications may be made to the embodiments shown without departing from the spirit and scope of the invention as defined by the accompanying claims as interpreted under patent law.

[0061] 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.

[0062] 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.