Patent Application
20210356126
The present invention relates to apparatuses, systems and methods for identifying and rectifying unstable flame conditions in industrial burners and preventing burner flame outs.
Industrial burners are commonly used in process heaters, boilers, furnaces, incinerators, and other fired heating systems to produce heat for petroleum refining, chemical production, petrochemical production, petroleum production, and other large-scale industrial processes.
Heretofore, flame Scanners have been used to monitor industrial burners in order to detect whether the burner flame has gone out, and to notify the system operator accordingly. In some cases, the loss of a burner flame can lead to the occurrence of a fire or explosion, potentially resulting in deaths or serious injuries, as well as causing significant damage to the equipment or the processing facility. The loss of a burner flame can also result in the release of hydrocarbons or other harmful pollutants to the atmosphere.
Flame scanners typically include an ultraviolet (UV) sensor, an infrared (IR) sensor, or both a UV and an IR sensor. UV Scanners are typically used for light gaseous fuels composed of hydrogen and/or lighter hydrocarbons such as C4 and less. IR Scanners are typically used for liquid fuels, or gaseous fuels composed of heavier hydrocarbons of C4 and above. Scanners which include both a UV sensor and an IR sensor can be used for applications which require both.
In order to determine whether the burner flame has gone out, flame sensors are also typically capable of distinguishing between a real flame condition and false flame condition. This is known as “flame discrimination.” A false flame condition can be produced by the detection of UV or IR light radiating, for example, from hot refractory or metal materials around the burner.
Unfortunately, although the flame monitoring systems heretofore used in the art have been effective for determining whether the burner flame has gone out, they have not been effective for (a) identifying unstable flame conditions which are likely to lead to a burner flame-out event and (b) notifying the system operator ahead of time so that the unstable conditions can be rectified before the flame-out occurs.
The ability to predict and prevent the occurrence of burner flame-out events would significantly improve the safety of the combustion system. In addition, when the burner flame becomes unstable, significant increases in NOx, CO, VOC, UHC, particulates, HAP, and/or other emissions from the burner can occur. Also, the output and performance levels of the burner are negatively affected. Consequently, if the system operator had knowledge of such unstable flame conditions, the operator would be able to make the necessary adjustments to not only prevent a flame-out event from occurring, but to also bring the burner emissions back in line and restore the output and performance levels of the burner.
The present invention provides a system and a method for preventing a burner flame out event. The inventive system and method satisfy the needs and alleviate the problems discussed above. The inventive system and method are effective for identifying and warning the system operator of erratic and other unstable flame conditions, or shutting the burner down, prior to a flame out event, so that the unstable conditions can be rectified in order to (a) prevent a flame out from occurring, (b) bring the emissions from the burner back into line, and (c) restore the output and performance levels of the burner.
In one aspect, there is provided a system for detecting unstable conditions and preventing a burner flame out. The system preferably comprises: (a) a flame scanner which determines and transmits UV and/or IR wave period or frequency information and UV and/or IR amplitude information for a flame of a burner and (b) a flame stabilization metering module which receives the UV and/or IR wave period or frequency information and UV and/or IR amplitude information transmitted by the flame scanner.
The flame stabilization metering module preferably comprises a processing unit and a program code which is embodied on or in one or more computer readable storage components. The program code embodied on or in the one or more computer readable storage components is readable by the processing unit to cause the flame stabilization metering module to perform a programmed procedure in which the flame stabilization metering module automatically (i) determines, either directly or indirectly, whether a UV and/or IR amplitude of the flame is less than a high amplitude instability set point and/or greater than a low amplitude instability set point for the UV and/or IR amplitude and/or (ii) determines, either directly or indirectly, whether a UV and/or IR wave period of the flame is greater than a short period stability set point and/or less than a long period stability set point for the UV and/or IR wave period.
In another aspect, there is provided a method for detecting unstable conditions and preventing a burner flame out. The method preferably comprises the steps of: (a) automatically determining, either directly or indirectly, whether a UV and/or IR amplitude of a flame of a burner is less than a high amplitude instability set point for the UV and/or IR amplitude and (b) automatically determining, either directly or indirectly, whether a UV and/or IR wave period of the flame is greater than a short period instability set point for the UV and/or IR wave period.
Further aspects, features, and advantages of the present invention will be apparent to those in the art upon examining the accompanying drawings and upon reading the following detailed description of the preferred embodiments.
An embodiment 2 of the inventive system for detecting unstable conditions and preventing burner flame out events is illustrated in the
Each flame scanner 4 used in the inventive flame out prevention system 2 can be generally any type of burner flame scanner which is capable of continuously measuring and transmitting information as to the UV and/or IR wave period t (or frequency) and the amplitude x of the burner flame 10 (see
The flame scanner 4 used in the inventive system 2 will preferably be a PROFLAME or PROFLAME+ Integrated Flame Scanner available from Zeeco, Inc. Other flame scanners adaptable for use in the inventive flame out prevention system 2 are available from Fireye, Durag, IRIS, Lamtech, Honeywell, and Siemens.
Although the flame scanner 4 has been described as being a UV scanner, an IR scanner, or both, it will be understood that the scanner 4 and the inventive flame out prevention system 2 could alternatively or additionally be configured to use any other type of electromagnetic wave sensor which can detect the presence and behavior of the burner flame 10.
The flame stabilization metering module 6 used in the inventive flame out prevention system 2 preferably comprises: a housing 12: a microprocessor or other computer processing unit (CPU) 14; and at least one computer readable medium, device, or other computer readable storage component 16. The one or more computer readable storage components 16 can be permanently installed in the module housing 12 or can consist of, or can include, a component, e.g., a thumb drive or other portable memory device, which is removably installed in or removably connected to the module 6. The flame stabilization metering module 6 also includes a program code which is embodied on or in the one or more computer readable storage components 16.
The flame stabilization metering module 6 preferably either (a) receives the UV and/or TR wave period reading t (or frequency) and the amplitude reading x directly from the flame scanner(s) 4, or calculates or otherwise determines these values using the information received from the scanner(s) 4.
In accordance with the steps of the programmed procedure which is embodied on or in the one or more computer readable storage components 16, the flame stabilization metering module 6 also preferably acts to automatically determine, either directly or indirectly, whether: (i) the UV and/or IR amplitude x of the flame 10 is less than a high amplitude instability set point for the UV and/or IR amplitude; and/or (ii) the UV and/or IR amplitude x of the flame 10 is greater than a low amplitude instability set point for the UV and/or IR amplitude; and/or (iii) the UV and/or IR wave period t of the flame 10 is greater than a short period stability set point for the UV and/or IR wave period; and/or (iv) the UV and/or IR wave period t of the flame 10 is less than a long period stability set point for the UV and/or IR wave period.
When a burner flame 10 becomes unstable, it will typically be the case that (a) the UV or IR amplitude x of the flame will increase significantly and/or (b) the wave period t will become significantly shorter (i.e., the frequency of the signal will increase significantly). Consequently, it is preferred that the flame stabilization metering module 6 act, in accordance with the programed procedure, to automatically directly, or indirectly, determine both (i) whether the UV and/or IR amplitude x of the flame 10 is less than the high amplitude instability set point for the UV and/or IR amplitude and (ii) whether the UV and/or IR wave period t of the flame 10 is greater than the short period stability set point for the UV and/or IR wave period. Moreover, it is most preferred that the flame stabilization metering module 6 also act, in accordance with the programed procedure, to further automatically directly, or indirectly, determine both (a) whether the UV and/or IR amplitude x of the flame 10 is greater than the low amplitude instability set point for the UV and/or IR amplitude and (b) whether the UV and/or IR wave period t of the flame is less than a long period stability set point for the UV and/or IR wave period
As used herein and in the claims, to determine or apply any of these values “indirectly” means that a known functionally equivalent value is determined and used. By way of example, but not by way of limitation, since the reciprocal of the wave period t of the UV and/or IR signal of the burner flame is its frequency, the frequency of the signal can be used as an alternatively to the wave period t, with any values or ranges cited for the wave period t simply being converted to the corresponding values or ranges for the frequency of the signal based upon the reciprocal relationship between wave period and frequency. As another example, but also not by way of limitation, although the amplitude x of the UV and/or IR signal shown in
The high amplitude instability set point for the UV and/or IR amplitude can be either a high amplitude warning point or a high amplitude shutoff point. The low amplitude instability set point for the UV and/or IR amplitude can be either a low amplitude warning point or a low amplitude shutoff point. The short period instability set point for the UV and/or IR wave period can be either a short period warning point or a short period shutoff point. The long period instability set point for the UV and/or IR wave period can be either a long period warning point or a long period shutoff point.
The flame stabilization metering module 6 preferably acts, in accordance with the programed procedure, to compare the UV and/or IR signal to (a) a high amplitude warning set point and then also to a higher shutoff set point if the amplitude of the signal equals or exceeds the warning point, (b) a low amplitude warning set point and then also to a lower shutoff set point if the amplitude of the signal equals or is less than the warning point, (c) a short period warning set point and then also to a shorter shutoff set point if the wave period of the signal equals or is less than the warning point, and (d) a long period warning set point and then also to a longer shutoff set point if the wave period of the signal equals or exceeds the warning point.
In accordance with the steps of the programmed procedure, the program code embodied on or in the one or more computer readable storage components 16 preferably further causes the flame stabilization and metering module 6 to automatically provide a warning signal if: (i) the UV and/or IR amplitude of the flame is not less than the high amplitude warning set point; (ii) the UV and/or IR amplitude of the flame is not less than the high amplitude shutoff set point; (iii) the UV and/or IR amplitude is not greater than the low amplitude warning set point; (iv) the UV and/or IR amplitude is not greater than the low amplitude shutoff set point; (v) the UV and/or IR wave period of the flame is not greater than the short period warning set point; (vi) the UV and/or IR wave period is not greater than the short period shutoff set point; (vii) the UV and/or IR wave period is not less than the long period warning set point; or (viii) the UV and/or IR wave period is not less than the long period shutoff set point.
In addition, the program code embodied on or in the one or more computer readable storage components 16 can optionally also cause the flame stabilization and metering module 6 to automatically act, in accordance with the programmed procedure, to shut off the burner 8 if: (i) the UV and/or IR amplitude of the flame 10 is not less than the high amplitude shutoff set point; (ii) the UV and/or IR amplitude is not greater than the low amplitude shutoff set point; (iii) the UV and/or IR wave period of the flame 10 is not greater than the short period shutoff set point; or (iv) the UV and/or IR wave period is not less than the long period shutoff set point.
Alternatively or in addition, at any time that a warning set point or a shutoff set point for the UV and/or IR wave period or amplitude of burner flame 10 is reached, the program code can optionally cause the flame stabilization and metering module 6 to automatically act, in accordance with the programmed procedure, to: (i) adjust the air level to the burner; (ii) adjust the fuel pressure to the burner; and/or (iii) adjust the fuel composition to the burner.
Although the UV and/or IR wave period and amplitude warning and shutoff set points for the flame 10 of the burner 8 can be determined and set in accordance with any acceptable standard or using any acceptable technique, the wave period and amplitude warning and shutoff set points will preferably be based upon the normal UV and/or IR wave period and amplitude ranges exhibited by the burner 8 when operating under stable conditions.
Normal changes or fluctuations of the UV and/or IR wave period and amplitude of the burner flame 10 will be influence, for example, by the operating conditions of the burner 8 which can include, but are not limited to: the fuel composition range; the type of burner use (e.g., flameless combustion, internal flue gas recirculation, Next Generation NOx, Ultra-Low NON, conventional emissions, lean pre-mixed, staged fuel, staged air, etc.); the nature of the oxygen source (e.g., fresh air, turbine exhaust, oxygen enrichment, external flue gas recirculation, etc.); the use of steam injection; the use of water injection: the addition of inerts such as N2 or CO2; etc.
In order to establish the normal baseline UV and/or IR wave period and amplitude ranges of the burner flame 10 in order to derive the desired warning and shutoff set points for the burner 8, the method of the present invention preferably comprises the initial step, after the flame scanner 4 is set up, of monitoring the flame 10 produced by the fuel under stable operating conditions to determine, either directly or indirectly, (i) an upper range limit and a lower range limit for the UV and/or IR amplitude of the flame 10 and (ii) an upper (long) range limit and a lower (short) range limit for the UV and/or IR wave period of the flame 10.
Based upon these normal baseline range limits for the burner 10, the wave period and amplitude warning set points and shut off set points for the burner 8 as related to the fuel in question can be automatically determined by the flame stabilization and metering module 6 as part of the programmed procedure, or can be determined and entered by the system operator.
Each high amplitude instability set point (e.g., both the warning point and the higher shut off point) will preferably be a point in the range of from 100% to 300% of the upper baseline range limit for the UV and/or IR amplitude of the flame 10 for the fuel in question under the stable operating conditions. Each low amplitude instability set point (e.g., both the warning point and the lower shut off point) will preferably be a point in the range of from 5% to 90% of the upper baseline range limit for the UV and/or IR amplitude. Each short period instability set point (e.g., both the short period warning point and shorter shut off point) will preferably be a point in the range of from 5% to 90% of the upper baseline range limit for the UV and/or IR wave period of the burner flame 10 for the fuel in question under stable operating conditions. Each long period instability set point (e.g., both the long period warning point and the longer shut off point) will preferably be a point in the range of from 100% to 300% of the upper baseline range limit for the UV and/or IR wave period.
Each high amplitude instability set point will more preferably be in the range of from 125% to 225% of the upper baseline range limit for the UV and/or IR amplitude of the flame 10. Each low amplitude instability set point will more preferably be in the range of from 5% to 60% of the upper baseline range limit for the UV and/or IR amplitude of the flame 10. Each short period instability set point will more preferably be in the range of from 5% to 60%, more preferably 5% to 40%, of the upper baseline range limit for the UV and/or IR wave period for the flame 10. Each long period instability set point will more preferably be in the range of from 125% to 225% of the upper baseline range limit for the UV and/or IR wave period for the flame 10.
The high amplitude warning set point for the burner flame 10 for the fuel in question will preferably be in the range of 125% to 175%, more preferably about 150%, of the upper baseline range limit for the UV and/or IR amplitude of the flame 10. The high amplitude shutoff set point for the fuel in question will preferably be in the range of 175% to 225%, more preferably about 200%, of the upper baseline range limit for the UV and/or IR amplitude. The low amplitude warning set point for the fuel in question will preferably be in the range of 10% to 40%, more preferably about 20%, of the upper baseline range limit for the UV and/or IR amplitude. The low amplitude shut off set point for the fuel in question will preferably be in the range of 5% to 25%, more preferably about 10%, of the upper baseline range limit for the UV and/or IR amplitude.
The short period warning set point for the burner flame 10 for the fuel in question will preferably be in the range of from 10% to 40%, more preferably about 20%, of the upper (long) baseline range limit for the UV and/or IR wave period for the flame 10. The short period shut off set point for the fuel in question will preferably be in the range of 5% to 25%, more preferably about 10%, of the upper baseline range limit for the UV and/or IR wave period. The long period warning set point for the fuel in question will preferably be in the range of 125% to 175%, more preferably about 150%, of the upper baseline range limit for the UV and/or IR wave period. The long period shutoff set point for the fuel in question will preferably be in the range of 175% to 225%, more preferably about 200%, of the upper baseline range limit for the UV and/or IR wave period.
In the case where a plurality of different fuels are expected to be used in the burner 8, the method of the present invention preferably comprises the steps of: (i) separately operating the burner 8 under stable operating conditions for a period of time using each of the different fuels; (ii) during the step of operating, determining for each different fuel an upper range limit for the UV and/or IR amplitude of the flame 10 of the burner 8 using the fuel; (iii) during the step of operating, determining for each different fuel the upper range limit for the UV and/or IR wave period of the flame 10 using the fuel; (iv) determining which fuel provided the highest upper range limit for the UV and/or IR amplitude of the flame 10; and (v) determining which fuel provided the highest upper range limit for the UV and/or IR wave period of the flame 10.
Once the fuel providing the highest upper range limit for the UV and/or IR amplitude and the fuel providing the highest upper range limit for the UV and/or IR wave period have been determined, these highest amplitude and wave period range limit values will preferably be used as the baseline upper range limits to establish a single set of amplitude and wave period warning set points and shut off set points for the burner 8, calculated in the same manner as was described above for the case of a single fuel, which will be used for the burner 8 regardless of which of the fuels in question is being combusted.
As an alternative to the flame stabilization and metering module 6 automatically taking corrective action or shutting off the burner 8 in response to a determination that the burner flame 10 is or is becoming unstable, or that a flame out event is likely to occur, the system operator can act manually, in response to receiving a warning or shut off signal from the inventive system 2, to adjust the excess air level of the burner 8, adjust the fuel pressure to the burner 8, adjust the fuel composition to the burner 8, take other corrective actions, or any combination thereof. Examples of other actions which may be required could include, but are not limited to, shutting the burner 8 or the entire fired heating system down in order to clean any plugged fuel discharge ports, replace any damaged parts, and/or seal any air leaks in the fired heating system.
A flow chart illustrating the method 20 of the present invention for detecting unstable conditions and preventing a burner flame out event is illustrated in
In the inventive method 20 as illustrated in the flow chart of
Next, the flame stabilization and metering module 6 determines whether the UV and/or IR amplitude x of the burner flame 10 is less than the set point for the high amplitude warning. If not, the module 6 provides a warning signal W and then determines whether the UV and/or IR amplitude x is less than the set point for the high amplitude shutoff. If not, the module 6 either automatically shuts the burner 8 off or provides a signal to the operator to shut the burner 8 off.
Next, the flame stabilization and metering module 6 determines whether the UV and/or IR wave period t of the burner flame 10 is longer than the set point for the short period warning. If not, the module 6 provides a warning signal W and then determines whether the UV and/or IR wave period t is longer than the set point for the short period shutoff. If not, the module 6 either automatically shuts the burner 8 off or provides a signal to the operator to shut the burner 8 off.
Next, the flame stabilization and metering module 6 determines whether the UV and/or IR wave period t of the burner flame 10 is shorter than the set point for the long period warning. If not, the module 6 provides a warning signal W and then determines whether the UV and/or IR wave period t is less than the set point for the long period shutoff. If not, the module 6 either automatically shuts the burner 8 off or provides a signal to the operator to shut the burner 8 off.
If the flame stabilization and metering module 6 determines that none of the warning set points for the UV and/or IR wave period and amplitude of the burner flame 10 are met, the module 6 preferably also provides a signal indicating that the operation of burner 8 remains within the safe (stable) operating range.
It will be understood that the sequence of warning determinations provided in the left-hand column of the flow chart shown in
Thus, the present invention is well adapted to carry out the objectives and attain the ends and advantages mentioned above as well as those inherent therein. While presently preferred embodiments have been described for purposes of this disclosure, numerous changes and modifications will be apparent to those in the art. Such changes and modifications are encompassed within the invention as defined by the claims.
