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Incinerator noise control 2
- Thread starter cctdiag
- Start date
Hi cctdiag,
I'm not an expert with incinerators either, but at a couple of our gas plants we have had noise problems with our waste gas incinerators. The problem was that they were undersized. When the wind blew a certain way, a roar came across the plant, I was assured it was only the incinerator.
More details on your problem might help others, like the noise level you are trying to achieve (is it a "normal" noise level or are you trying to get to a level where noise supression equipment is required) and the type of incincerator (waste gas, human waste, etc).
Checking the incinerator size might be a good place to start, depending on the type of incinerator. If you don't have an expert in house, the manufacturer might check the sizing for you.
hiebs
I'm not an expert with incinerators either, but at a couple of our gas plants we have had noise problems with our waste gas incinerators. The problem was that they were undersized. When the wind blew a certain way, a roar came across the plant, I was assured it was only the incinerator.
More details on your problem might help others, like the noise level you are trying to achieve (is it a "normal" noise level or are you trying to get to a level where noise supression equipment is required) and the type of incincerator (waste gas, human waste, etc).
Checking the incinerator size might be a good place to start, depending on the type of incinerator. If you don't have an expert in house, the manufacturer might check the sizing for you.
hiebs
- Thread starter
- #3
Hi Hiebs,
At the moment this is a hypothetical question, with no sound levels to work to, I have to just accept the stack is noisy and needs silencing. I am being asked to specify any appropriate noise control method - the hypothetical stack is from an energy from waste incinerator.
Thanks for the suggestion of checking with a manufacturer, I will explore this avenue also.
cctdiag
At the moment this is a hypothetical question, with no sound levels to work to, I have to just accept the stack is noisy and needs silencing. I am being asked to specify any appropriate noise control method - the hypothetical stack is from an energy from waste incinerator.
Thanks for the suggestion of checking with a manufacturer, I will explore this avenue also.
cctdiag
You really need to identify the source. I'm currently looking at installing a vapor combustion unit for a distribution terminal. One vendor said that their standard unit is quite noisy due to the low cost fan they provide. They have a fan option that is more $$ but less noisy.
I suspose the burners could also be a factor. Until you know the source of the noise, trying to come up with solutions to reduce the noise levels is premature.
I suspose the burners could also be a factor. Until you know the source of the noise, trying to come up with solutions to reduce the noise levels is premature.
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1
- #5
Does your incinerator stack have any acoustic screen device? And what about the burner? For noise suppression normally burners are equipped with plenum chambers devices.
I think you should contact your incinerator licensor on this subject.
For noise control specialists I found the site bellow maybe it helps
Regards
Luis Marques
I think you should contact your incinerator licensor on this subject.
For noise control specialists I found the site bellow maybe it helps
Regards
Luis Marques
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1
- #6
Do you have a problem or is this just "make-work"?
If it's a real problem, you may not have many options, and those you do have will be highly conditioned by the original design and the existing equipment.
In the combustion chamber, the noise is generated by the combustion process itself (with a thermo-acoustic efficiency of between 0.5E-06 and 5E-06. The actual efficiency will depend on the density of combustion (energy flux per volume)in an approximate range 2.0E04 - 2.0E05 Btu/h_ft^3. That noise is generated by the combustion.
Where you are will depend on the combustion chamber size AND the burner design.
The burner manufacturer can play with some of the noise by changing the flame density close to the burner.
The noise gets out into the atmosphere through the walls (which will not be very transmissive), the air inlets (which you or the burner manufacturer can probably silence with mufflers), and the flue gas outlet or stack ( which you may not be able to do anything about). Any time you add mufflers to the air or flue gas flow sytemd you change the thermal energy balance and this messes with the temperatures. [Having said that, you may have muffler options but depending on the stack diameter, it may involve rebuilding the unit.]
If you have a big stack outlet, most of the noise may be coming from that point. You could make a guess about how much noise comes rom where by adding up all the air inlet area and flue outlet area and pro-rating the noise on the basis that the noise energy density at those points is roughly equal.
Then you have any mechanical noise. Do you have fans or blowers, are the (liquid) burners mechanically atomised or with steam or air, and valve noise etc can add to your problem.
Before you can start you need to do a walk-around and identify the noise sources. Isolate those you can and get a noise reading at a known distance from that source (3 - 5 ft at the most if you can manage it). Get a spectrum analysis as well and record the linear reading as dB (as well as dBA) if you want a realistic analysis.
When you are left with just the combustion noise, see how that varies with location. When you are close to the unit, you hear mainly the noise coming from the burner air inlets. At a distance (more than 2 heights) you will hear the entire thing including the stack output.
Then find out where the problem exists. Locally to the unit or a mile away?
Watch out for pulsing noises (vibrations or regular variations in noise volume). These indicate some sort of instability, either with the combustion process or as a choking condition in the flow. These will not register as dB nor appear in a conventional frequency spectrum and need to be debugged by more sophisticated means. If you have pulsing, get a recording of the noise for your analyst to work with in an oscilloscope or computer-based equivalent.
[Hiebs noise concern (above) was probably the wind hitting the air inlet in a certain way and intensifying the combustion density.]
A company which sometimes looks at this type of issue can be found at
Good luck![[smile]](/data/assets/smilies/smile.gif "[smile] [smile]")
If it's a real problem, you may not have many options, and those you do have will be highly conditioned by the original design and the existing equipment.
In the combustion chamber, the noise is generated by the combustion process itself (with a thermo-acoustic efficiency of between 0.5E-06 and 5E-06. The actual efficiency will depend on the density of combustion (energy flux per volume)in an approximate range 2.0E04 - 2.0E05 Btu/h_ft^3. That noise is generated by the combustion.
Where you are will depend on the combustion chamber size AND the burner design.
The burner manufacturer can play with some of the noise by changing the flame density close to the burner.
The noise gets out into the atmosphere through the walls (which will not be very transmissive), the air inlets (which you or the burner manufacturer can probably silence with mufflers), and the flue gas outlet or stack ( which you may not be able to do anything about). Any time you add mufflers to the air or flue gas flow sytemd you change the thermal energy balance and this messes with the temperatures. [Having said that, you may have muffler options but depending on the stack diameter, it may involve rebuilding the unit.]
If you have a big stack outlet, most of the noise may be coming from that point. You could make a guess about how much noise comes rom where by adding up all the air inlet area and flue outlet area and pro-rating the noise on the basis that the noise energy density at those points is roughly equal.
Then you have any mechanical noise. Do you have fans or blowers, are the (liquid) burners mechanically atomised or with steam or air, and valve noise etc can add to your problem.
Before you can start you need to do a walk-around and identify the noise sources. Isolate those you can and get a noise reading at a known distance from that source (3 - 5 ft at the most if you can manage it). Get a spectrum analysis as well and record the linear reading as dB (as well as dBA) if you want a realistic analysis.
When you are left with just the combustion noise, see how that varies with location. When you are close to the unit, you hear mainly the noise coming from the burner air inlets. At a distance (more than 2 heights) you will hear the entire thing including the stack output.
Then find out where the problem exists. Locally to the unit or a mile away?
Watch out for pulsing noises (vibrations or regular variations in noise volume). These indicate some sort of instability, either with the combustion process or as a choking condition in the flow. These will not register as dB nor appear in a conventional frequency spectrum and need to be debugged by more sophisticated means. If you have pulsing, get a recording of the noise for your analyst to work with in an oscilloscope or computer-based equivalent.
[Hiebs noise concern (above) was probably the wind hitting the air inlet in a certain way and intensifying the combustion density.]
A company which sometimes looks at this type of issue can be found at
Good luck
That is some good information, Flareman, a lot of which is hard to find in one place.
As an aside to your comment about my noise concern, you are correct. Our problem was the wind hitting the air inlet on a natural draft incinerator. The incinerator was not adjusted properly so the operators left the louvers wide open to keep the stack temperature within a certain range. We've since had the manufacturer out to help adjust the makeup gas flow (I believe they also found some louvers that the operators actually use).
Hiebs
As an aside to your comment about my noise concern, you are correct. Our problem was the wind hitting the air inlet on a natural draft incinerator. The incinerator was not adjusted properly so the operators left the louvers wide open to keep the stack temperature within a certain range. We've since had the manufacturer out to help adjust the makeup gas flow (I believe they also found some louvers that the operators actually use).
Hiebs
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