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Denizli Power Station
Acoustical study far field noise
U. Scholz
Document no.
Date of first issue:
Revision
Number of pages:
PA-10003
2010-01-08
B – 2010-02-02
11
Prepared:
Checked:
U. Scholz
C Klockar
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Table of contents
1
2
3
4
5
6
7
8
Purpose / Introduction / Summary ............................................................... 3
Background .................................................................................................... 3
Requirements for the surroundings of the new power plant ..................... 3
Noise prediction calculation ......................................................................... 4
Results ............................................................................................................ 7
Technical and Commercial Impact ............................................................... 8
Conclusions ................................................................................................... 8
Appendices .................................................................................................... 9
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Purpose / Introduction / Summary
At the site Denizli a power plant with a capacity of 800 MW is planned.
This acoustical study contains the necessary information about the far field noise
impact of this power plant on the nearest residences for the Environmental Impact
Study.
To evaluate the acoustical impact of the new power plant a noise prediction
calculation was carried out. As a first approach, a standard arrangement with all
relevant noise sources was implemented in the model.
2
Background
As basis for the acoustical engineering task of the industrial facility at Denizli the
following documents were used:
[1] Layout Plot Plan, Drawing: P7158.3.000/7
[2] General Arrangement, Drawing: P7158.3.100/5, Two F Class combustion
turbines with HRSG and one stream turbine main cooling system is an ACC
[3] Map of the area with landscape information, Denizli – M22-b3, Scale 1:25'000
[4] Acoustical performance guarantee according to document No.:P7158.4/13, Rev.:
14, 4. Performance Guarantees, Chapter 3.5 and 3.6,
[5] Acoustical World Bank Standards defined in : "Pollution Prevention Abatement
Handbook, World Bank Group Effective July 1998, Thermal Power: Guidelines
for New Plants
3
Requirements for the surroundings of the new power plant
The basis of the acoustical requirements for the far field is given in [4] and [5]. Table
1 was given with [4]:
Table 1, Acoustical far field requirements according to [4]
The first guarantee is according to the Turkish Law; the second one (Option)
represents the World Bank standards.
The guarantee shall be applied at the nearest residences, Yokusbasi Village (IP1,
about 1700 m to the East) and Kaklik Town (IP2, about 1440 m to the South)
(distances from the centre of the plant according to [1] and [3]).
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Noise prediction calculation
Noise emissions in the vicinity of the power plant are influenced by several factors, all
of which must be considered for the final attainment of "Far Field" noise levels.
• Prevailing climatic conditions, i.e. wind speed and wind direction, temperature
• Ground and meteorological correction
• Screening external to the site, i.e. vegetation and topographic situation etc.
• Attenuation characteristics and insertion losses of buildings, etc.
• Directivity factors applicable to certain noise sources. i.e. air intake, stack
opening, etc.
• Plant layout effects, i.e. the use of plant items and buildings to screen or prevent
noise transmission in particular directions as well as reflections.
A calculation procedure is given in the following international standards:
• ISO 9613-1 and ISO9613-2: Acoustics- Attenuation of sound during propagation
outdoors
• VDI 3733 Noise at pipes (Used for stack directivity)
The software Cadna/A, Version 3.72.131 was used to calculate far field noise levels.
It is developed by Datakustik in Munich and is based on these Standards.
Presumptions for the noise calculation:
• Wind speed: 3 m/s
• Wind direction – down wind from the source to the receptor point worst case
scenario
• Ambient temperature: 10ºC
• Humidity: 70% (the combination of ambient temperature and humidity
represents a worst case scenario)
• Ground and metrology effect: 0.2, semi hard ground for the area of the new
power plant; 0.5 for the area outside the power plant
• Number of reflections: 1
• Altitude of receiver points 6 m above the relevant ground level
• General Layout of the plant according to [1]
• Landscape according to [1] and [3]
The noise prediction calculation is an octave band calculation in which the power
plant noise sources are represented by equivalent flat faces, lines or point sources
placed in a 3 dimensional co-ordinate system.
Sound power levels for each (single) emitting component are calculated from basic
sound power data (benchmark data) and relevant partial attenuation (acoustic
measures). The data used were taken from different measured power plant with
about the same size and a similar arrangement.
The far field transmission path attenuation is estimated by means of spherical
divergence, air absorption and additive correction for ground and meteorological
effects, vegetation, topography and screening. Stack directivity and reflections are
also considered in this calculation procedure.
The predicted receiver point sound pressure levels correspond to energy mean
values within the meteorological conditions used.
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The order of magnitude of expected LAeq standard deviation is 1 ÷ 3 dB according to
the standard. The engineers of PRO-Acoustics have been able to calibrate the model
calculation with field measurements at different power plant sites within the last
years. According to our experience the deviation is below 1 dB for distances up to
400 m. With longer distances the deviation between calculation and measurement
becomes higher but the calculated values are higher than the measured values (an
additional safety margin) this is the conclusion from multiple field measurements.
After calculation of the "emission relevant" source sound power level, in which the
correction terms for the selected attenuation are already considered, the transfer
function for divergence will be determined.
The results of this calculation represent the noise rating level emitted by each single
source or group of sources at the receiver point. The total octave band sound
energies arriving at the receiver are calculated by adding each single source impact
on an energy basis.
For this project it was important to take into account the topographic situation
because the site is surrounded by hills. One receiver points (IP1) is located on these
hills. More than 650 isohypses were used (imported and digitized) to model the
landscape.
The grid calculation is based on approximately 250'000 receiver points in the vicinity
of the power station. Using an interpolation procedure, a noise contour map was
calculated.
Figure 1 show the landscape used in the acoustical model. The picture is for
illustration the complex geometry of the model.
IP1
Plant
IP2
Figure 1: Denizli, landscape height in meter
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Figure 2 and Figure 3 shows the view from the used immission points in direction
power plant. From IP1 only the two stack mouths a re visible. From IP2 the plant is
visible but the lower section is screened. These pictures show the impact of the
landscape only, taken into account the vegetation the screening effect will be higher.
Plant
Only exhaust stack
mouth visible
IP1
Figure 2: View in direction power plant from IP1- Yokusbasi Village
Plant
IP2
Figure 3: View in direction power plant from IP2 - Kaklik
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Results
In a first step it should be checked what the impact in the far field would be using the
acoustical near field requirements according to [4].
Standard arrangement with industry standard components was used which means no
extra effort was taken into account.
Table 2 contains the sound power level of the groups of noise sources and the
foreseen acoustical measures.
Component
ALL
Air Intake
Opening
Air Intake duct
Turbine building
Turbine building
ventilation intake
Turbine building
ventilation outlet
roof fans
Generator
LWA
Measures
[dB(A)]
122
106
Sound power level per unit, Standard with silencer and filter, taken into
account an anti icing with compressor air
99
Sound power level per unit, standard duct, no special insulation,
silencer located partly inside the building
114
Standard cladding, no special requirements, this noise source was
calculated with worst case conditions, steam turbine bypass operation
during start up or shut down of the plant, during normal operation the
sound power level will be significantly lower
2
110
Standard weather hoods, about 70 m open surface, no special
requirements, this noise source was calculated with worst case
conditions, steam turbine bypass operation during start up or shut down
of the plant, during normal operation the sound power level will be
significant lower
106
Standard fans
99
Exhaust Diffuser
103
HRSG, including
transition duct
stack body and
pipe work
Stack Mouth
Feed water pump
set
Main Transformer
107
Aux. Transformer
Atmospheric
drain vessel, start
up ejector
Gas receiving
and metering
station
ACC
Combustion
turbine, generator
re-cooler
Sound power level per unit (GT Generators outdoor only ST Generator
inside turbine building), the Generators are equipped with a standard
enclosure with integrated ventilation
Sound power level per unit, standard duct with thermal / acoustical
insulation
Sound power level per unit, Standard outdoor HRSG with thermal
insulation for the gas path and the steam piping
105
112
Sound power level per unit, short silencer in the exhaust system
Standard equipment
104.3
Sound power level per unit (three main transformers) Standard
equipment
Sound power level per unit
Operation during start up only, plant on part load during the main
operation of the blow out. Standard single stage silencer required
90
105
99
Standard equipment
114
111
Standard ACC
Both units together, worst case scenario, summer operation day time,
during night time the re-cooler will have a significant lower sound power
level, since the fans run usually temperature controlled
Table 2, description of the noise sources
Power plants with this type of configuration were built and measured several times.
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The result of the noise prediction calculation is summarized in table Table 3.
Location
IP1- Yokusbasi Village
Calculated sound pressure level, Lp
40 dB(A)
IP2 - Kaklik
43 dB(A)
Table 3: Results from noise prediction calculation using the acoustical near field
requirements and standard equipment
Table 3 shows that with standard components the World Bank standard is fulfilled
with a comfortable safety margin. The values in Table 2 are the calculated values at
the locations IP 1 and IP 2. No adjustments were made for tonality and impulses. The
contract with the vendors has clearly to exclude these effects.
This margin could be used for further optimization or for noise sources which were
not possible to include in this early project phase.
6
Technical and Commercial Impact
The equipment used in the model represents acoustical standard equipment. It was
not necessary to integrate relevant extra costs to reach the calculated sound
pressure level for the far field. Silencers in the air intake system and in the exhaust
system do not represent an extra effort since these components are state of the art
for combustion turbine power plants and necessary for the near field requirements.
The requirements regarding tonality and impulses represent no extra effort either.
Furthermore it has to be mentioned that the used acoustical design has no negative
impact in the overall plant performance.
7
Conclusions
At the site Denizli it is possible to build a power plant which fulfils the acoustical
requirements given by the Turkish law. Furthermore it does not represent a relevant
extra effort to reach the World Bank standard. It should be possible to fulfil both
requirements with a significant safety margin.
Therefore the World Bank standards should be design criterion for the power plant.
The model calculation was made for a worst case scenario of the noise generation,
steam turbine bypass operation for start up and shut down (about 60% steam mass
flow generated in the HRSG's for this operation point) and on the other hand base
load operation for the air intake and the exhaust system.
No relevant extra effort in acoustical design is necessary for all main noise sources in
order to reach the acoustical requirements.
The example used in the report is based on the state of the art for acoustical design
of a power plant. The guarantee of the vendors should be the overall guarantee at
the receiver locations and not source by source. This gives the vendors the option to
apply new developments or special characteristics of the noise sources, which might
differ from vendor to vendor.
The acoustical requirements have to be guaranteed by the vendor as a make good
guarantee without positive tolerance.
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Appendices
Appendix 1
Position of the power plant and of the immission points using [1],
[2] and [3]
Appendix 2
Noise contour map Option A
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Appendix 1
Position of the power plant and of the immission points using [1], [2] and [3]
IP1
IP2
Plant
location
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Appendix 2
Noise contour map
IP1
Plant
location
40dB(A)
50dB(A)
45dB(A)
43dB(A)
IP2
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