Friday, June 5, 2009
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Earlier post "Quick Estimation of Noise Level Across Pressure Reducing Device", discussion has been focused on estimation of Noise level across pressure reducing device i.e. control valve, pressure relief valve, restriction orifice, etc based on generated internal acoustic energy and transmission losses. The table presented in this post is typical wall thickness for Schedule STD. Increases in wall thickness (e) will results higher transmission loss and lower noise level is expected. Besides, magnitude of transmission loss is also depends to line diameter (D). How to relates transmission loss with wall thickness for different diameter ?
Noise Level Estimation
Noise level at 1 meter from a pressure reducing device can be estimated from Sound Power Level (PWL) as discussed in "Sound Power Level (PWL) Prediction from AIV Aspect". The Sound Power Level will be transmitted across the pipe wall and emitted to atmosphere. There will be noise correction when Sound power is transmitted across pipe wall (metal).
Noise level at 1 meter from a pressure reducing device,
L1m = PWL - LA
where
PWL = Sound Power Level (from Sound Power Level (PWL) Prediction)
LA = Noise correction (dB)
Noise Correction
The noise correction is subject to wall thickness and pipe size. Thicker wall will result higher noise correction. Following are sets of noise correction equation for different pipe size and wall thickness.
For Nominal Diameter equal to 750 (30 inches) and smaller,
LA = C3.e3 + C2.e2 + C1.e + C0 ......[1]
For Nominal Diameter 900 (36 inches) and above,
LA = C1.Ln (e) + C0 .....[2]
Where
e = Pipe wall thickness (mm)
C0, C1, C2, C3 = Parameters
e = Pipe wall thickness (mm)
C0, C1, C2, C3 = Parameters
| Parameter for Noise Correction | |||||
| Nom.Dia. (Inch) | Eq. | C3 | C2 | C1 | C0 |
| 25 | 1 | 0.0580 | -1.2556 | 11.6751 | 26.0942 |
| 50 | 1 | 0.0319 | -0.8039 | 8.8155 | 25.7428 |
| 100 | 1 | 0.0070 | -0.3107 | 5.6726 | 25.7582 |
| 150 | 1 | 0.0046 | -0.2351 | 4.8724 | 24.2083 |
| 200 | 1 | -0.0002 | -0.0376 | 2.3897 | 31.0074 |
| 250 | 1 | 0.0023 | -0.1395 | 3.1106 | 28.5213 |
| 300 | 1 | 0.0013 | -0.0949 | 2.5482 | 29.9195 |
| 350 | 1 | 0.0012 | -0.0858 | 2.4017 | 29.2649 |
| 450 | 1 | 0.0008 | -0.0660 | 2.1185 | 30.5846 |
| 600 | 1 | 0.0003 | -0.0371 | 1.5550 | 32.7016 |
| 750 | 1 | 0.0007 | -0.0523 | 1.7118 | 31.1754 |
| 900 | 2 | - | - | 6.9521 | 27.3305 |
| 1050 | 2 | - | - | 10.4282 | 18.4957 |
Example
A pressure control valve (PV) passing 100,000 kg/h of gas with molecular weight (MW) of 22. The inlet condition is 87 barg and 50 degC and downstream pressure is about 7 barg. The pipe diameter is 18 inch with wall thickness of 9.53mm, estimate noise level at 1 m from PV.
PWL = 10 x Log [((87-7) / (87+1.01325))^3.6
x (100,000 / 3600)^2
x ((50+273.15)/22)^1.2]
+ 126.1
PWL = 167.5 dB
For 18 inches, equation [1] will be used.
LA = C3.e3 + C2.e2 + C1.e + C0
LA = 0.0008 x9.533 -0.0660x9.532 + 2.1185 x 9.53 + 30.5846
LA = 45.5 dB
Noise level at 1m,
L1m = PWL - LA
L1m = 167.5 - 45.5
L1m = 122 dBA
Related Topic
- Quick Estimation of Noise Level Across Pressure Reducing Device
- Assess AIV with "D/t-method"
- Extra Attention to Common Point and Similarity on AIV Failure
- Piping Excitation When Expose to Acoustic Energy
- Acoustic Induced Vibration (AIV) Fatigue
- Sound Power Level (PWL) Prediction from AIV Aspect
- Several Criteria and Constraints for Flare Network - Piping
- Flow Element (FE) Upstream or Downstream of Control Valve (CV) ?
Labels: Air Pollution Control, AIV, Safety
Tuesday, May 26, 2009
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Pressure reducing device such as control valve, pressure relief valve, restriction orifice, etc, there will be pressure drop and mass passing through these device, internal acoustic energy is generated and transmitted to downstream piping and potentially lead to severe piping excitation, vibration and stresses on downstream piping and potentially lead to fatigue failure. Internal acoustic energy transmitted along the pipe may also transmitted to through the pipe and emitted as Noise.
One of the common safety requirement is limit the noise level to 85 dBA (Noise level with A-weighted) in continuous exposure and 115 dBA during intermittent exposure. In earlier conceptual or Front End Engineering Design (FEED) stage, the noise level across pressure reducing device may be estimated to determine overall noise control philosophy. The following will present a simple method to estimate noise level generated at 1 meter from a pressure reducing device.
Noise Level Estimation
Noise level at 1 meter from a pressure reducing device can be estimated from Sound Power Level (PWL) as discussed in "Sound Power Level (PWL) Prediction from AIV Aspect". The Sound Power Level will be transmitted across the pipe wall and emitted to atmosphere. There will be noise correction when Sound power is transmitted across pipe wall (metal). The noise correction is subject to wall thickness. Thicker wall will result higher noise correction. Following are typical noise correction for pipe size and wall thickness.
Noise level at 1 meter from a pressure reducing device,
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Pressure reducing device such as control valve, pressure relief valve, restriction orifice, etc, there will be pressure drop and mass passing through these device, internal acoustic energy is generated and transmitted to downstream piping and potentially lead to severe piping excitation, vibration and stresses on downstream piping and potentially lead to fatigue failure. Internal acoustic energy transmitted along the pipe may also transmitted to through the pipe and emitted as Noise.One of the common safety requirement is limit the noise level to 85 dBA (Noise level with A-weighted) in continuous exposure and 115 dBA during intermittent exposure. In earlier conceptual or Front End Engineering Design (FEED) stage, the noise level across pressure reducing device may be estimated to determine overall noise control philosophy. The following will present a simple method to estimate noise level generated at 1 meter from a pressure reducing device.
Noise Level Estimation
Noise level at 1 meter from a pressure reducing device can be estimated from Sound Power Level (PWL) as discussed in "Sound Power Level (PWL) Prediction from AIV Aspect". The Sound Power Level will be transmitted across the pipe wall and emitted to atmosphere. There will be noise correction when Sound power is transmitted across pipe wall (metal). The noise correction is subject to wall thickness. Thicker wall will result higher noise correction. Following are typical noise correction for pipe size and wall thickness.
| Noise Correction | ||
| Nominal Dia. (Inch) | Wall thickness (mm) | Noise Correction (dB) |
| 25 | 3.38 | 54 |
| 50 | 3.91 | 50 |
| 100 | 6.02 | 50 |
| 150 | 7.12 | 49 |
| 200 | 8.18 | 48 |
| 250 | 9.3 | 47 |
| 300 | 9.53 | 47 |
| 350 | 9.53 | 46 |
| 450 | 9.53 | 46 |
| 600 | 9.53 | 45 |
| 750 | 9.53 | 43 |
| 900 | 9.53 | 43 |
| 1050 | 9.53 | 42 |
Noise level at 1 meter from a pressure reducing device,
L1m = PWL - LA
where
PWL = Sound Power Level (from Sound Power Level (PWL) Prediction)
LA = Noise correction from above table
Example
PWL = 10 x Log [((87-7) / (87+1.01325))^3.6
x (100,000 / 3600)^2
x ((50+273.15)/22)^1.2]
+ 126.1
PWL = 167.5 dB
Noise level at 1m,
L1m = PWL - LA
L1m = 167.5 - 46
L1m = 121.5 dBA
As the noise level at 1m (normal trim) is 121.5 dBA, this is far too big from normal requirement. A low noise trim control valve may be considered and/or acoustic insulation to be provided.
Related Topic
PWL = Sound Power Level (from Sound Power Level (PWL) Prediction)
LA = Noise correction from above table
Example
A pressure control valve (PV) passing 100,000 kg/h of gas with molecular weight (MW) of 22. The inlet condition is 87 barg and 50 degC and downstream pressure is about 7 barg. The pipe diameter is 18 inch with wall thickness of 9.53mm, estimate noise level at 1 m from PV.
PWL = 10 x Log [((87-7) / (87+1.01325))^3.6
x (100,000 / 3600)^2
x ((50+273.15)/22)^1.2]
+ 126.1
PWL = 167.5 dB
Noise level at 1m,
L1m = PWL - LA
L1m = 167.5 - 46
L1m = 121.5 dBA
As the noise level at 1m (normal trim) is 121.5 dBA, this is far too big from normal requirement. A low noise trim control valve may be considered and/or acoustic insulation to be provided.
Related Topic
- Assess AIV with "D/t-method"
- Extra Attention to Common Point and Similarity on AIV Failure
- Piping Excitation When Expose to Acoustic Energy
- Acoustic Induced Vibration (AIV) Fatigue
- Sound Power Level (PWL) Prediction from AIV Aspect
- Several Criteria and Constraints for Flare Network - Piping
- Flow Element (FE) Upstream or Downstream of Control Valve (CV) ?
Labels: Air Pollution Control, AIV, Safety
Wednesday, May 30, 2007
Today, wanna to bring to you a thesis related to OPRATION AND CONTROL OF AZEOTROPIC DISTILLATION COLUMN...this document may be a bit acedemic but it may bring certain level of benifits to many of us (Chemical & Process Engineers)...Enjoy...
This document bring us something relates to
- a concept for the design of heterogeneous distillation columns under aspects of operability.
- a self-optimizing control concept is provided for a sequence of three homogeneous azeotropic distillation columns with two recycles (boundary separation scheme)
- a short cut method is developed to compare the performance of homogeneous and heterogeneous sequences based on the sum of the reboiler duties for identical equipment
Operation and Control of Azeotropic Distillation Column Sequences
A doctoral thesis from the Automatic Control Laboratory (IfA), Swiss Federal Institute of Technology (ETH) Z¨urich.
Jan Ulrich
Continue receive FREE stuff & Update.......Subscribe by Email
Labels: Air Pollution Control, Column, Distillation, Operation
Saturday, May 26, 2007
Following earlier introduction to <<Optimized Gas Treating, Inc. (OGT) - Experts in CO2-Amine>>, there are some others FREE articles available on this site for download...Refer to below listing and relevant links...ENJOY...
By the way, if you know some good site related to Chemical & Process Engineering, (as you know, i am focusing on distillation recently) do recommend to me...i will crawl the website thoroughly...and let inform our lovely Chemical & Process Engineers...
Knowledge does not belongs to any of us but it belongs to ALL of US...Let Share It...I still believe the more you share, the more you will gain...
Related Post- ProMax from BR&E - Renowed Process Simulator in Gas Treating Industry
- Optimized Gas Treating, Inc. (OGT) - Experts in CO2-Amine
- Air Pollution Control & Tail Gas Treatment
Labels: Absorption, Air Pollution Control, Amine, Column, Design, Distillation, Global warming, Modelling, Packed Column, Packing, Process simulation, Tail Gas Treatment, Technology, Tower internals
Wednesday, May 23, 2007
This is a site recommended by KATMAR where i crawled earlier...Read earlier post...
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CAPC products line includes :
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Tellerette packing is a special design offered by CAPC...
Read...Tellerette Tower Packing Benefits/Features, How it Works, Benefits/Features and Tellerette packing technical Data Sheet
CAPC offer FREE articles / Brochures for many type of scrubber...most of the scrubber design is particularly for dust, tail gas control purposes...
Concurrent Packed Scrubbers
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Crossflow Packed Scrubbers
Vertical Air Washers
FRP Venturi Scrubbers for Corrosive Applications
Horizontal Air Washer
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Labels: Absorption, Air Pollution Control, Mist Eliminator, Packed Column, Packing, Scrubber, Separator, Tail Gas Treatment, Tower internals
