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Denizli Power Station

Acoustical study far field noise

U. Scholz Document no. PA-10003 Date of first issue: 2010-01-08 Revision B – 2010-02-02 Number of pages: 11 Prepared: U. Scholz Checked: C Klockar

Titel Document Revision Page:

Denizli / Far field noise study PA-10003 B – 2010-02-02 2/11


Table of contents 1 Purpose / Introduction / Summary ............................................................... 3 2 Background .................................................................................................... 3 3 Requirements for the surroundings of the new power plant ..................... 3 4 Noise prediction calculation ......................................................................... 4 5 Results ............................................................................................................ 7 6 Technical and Commercial Impact ............................................................... 8 7 Conclusions ................................................................................................... 8 8 Appendices .................................................................................................... 9




1 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]).




4 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.




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.

Figure 1: Denizli, landscape height in meter

IP1

Plant

IP2




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.

Figure 2: View in direction power plant from IP1- Yokusbasi Village

Figure 3: View in direction power plant from IP2 - Kaklik

IP2

IP1

Plant Only exhaust stack mouth visible

Plant




5 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 LWA [dB(A)]

Measures

ALL 122

Air Intake Opening

106 Sound power level per unit, Standard with silencer and filter, taken into account an anti icing with compressor air

Air Intake duct 99 Sound power level per unit, standard duct, no special insulation, silencer located partly inside the building

Turbine 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

Turbine building ventilation intake

110 Standard weather hoods, about 70 m2 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

Turbine building ventilation outlet roof fans

106 Standard fans

Generator 99 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

Exhaust Diffuser 103 Sound power level per unit, standard duct with thermal / acoustical insulation

HRSG, including transition duct stack body and pipe work

107 Sound power level per unit, Standard outdoor HRSG with thermal insulation for the gas path and the steam piping

Stack Mouth 105 Sound power level per unit, short silencer in the exhaust system

Feed water pump set

112 Standard equipment

Main Transformer 104.3 Sound power level per unit (three main transformers) Standard equipment

Aux. Transformer 90 Sound power level per unit

Atmospheric drain vessel, start up ejector

105 Operation during start up only, plant on part load during the main operation of the blow out. Standard single stage silencer required

Gas receiving and metering station

99 Standard equipment

ACC 114 Standard ACC

Combustion turbine, generator re-cooler

111 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.




The result of the noise prediction calculation is summarized in table Table 3.

Location Calculated sound pressure level, Lp

IP1- Yokusbasi Village 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.




8 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




Appendix 1

Position of the power plant and of the immission points using [1], [2] and [3]

IP1

IP2

Plant location




Appendix 2 Noise contour map

IP1

40dB(A)

Plant location

IP2

45dB(A)

43dB(A)

50dB(A)

denizli power station acoustical study far field noise document revision page: denizli / far field...

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