NOISE REDUCTION OPERATIONS ON COOLING TOWERS AND ON COOLING PLANTS

Over the last years the industrial and civil plants realization put a growing emphasis on the evaluation and restraint of the acoustic impact. In the specific case of cooling towers, this problem has an outmost importance; for this reason SCAM T.P.E. S.r.l. developed inside its organization the ability to predict and control the acoustic emissions. The experience achieved in this field led SCAM T.P.E. S.r.l. to apply an advanced calculation program for the acoustic impact of its cooling towers through the collaboration of companies specialized in the realization of solutions for the acoustic restraint.

The cooling tower is an equipment made up of an ensemble of sound sources characterized by different spectral trends set on different positions. In its acoustic analyzes SCAM T.P.E. S.r.l. considers three main sound sources: impeller rotation in the fan group, the reverberation in the tower body on the same frequencies emitted by the group and the impact produced by the water on the free surface of the same.   

For the calculation of the result of the PWL sound power level generated (ISO 3746-3744) it is considered the sum of the volume and the tower sources; granting in this way the sound pressure medium level (intended as the logarithmic sum of the levels in n. measuring positions on various heights) equal to the sound pressure value indicated at the desired distance by the envelope of the whole reference source, then along the perimeter and in coverage (outside flow) in free field.    

The acoustic impact of all cooling towers can be reduced by adequate silencing options, by considering that the low-medium frequencies (higher for the fan group) go through long distances bypassing the obstacles, while the medium-high frequencies (engraving for the sound of the water) are reduced by distance and by possible barriers. Basing on specific acoustic requirements, SCAM T.P.E. S.r.l. is able to support customer in the technical-economic optimization of the more suitable solution based on the reception real point and on the requested values, by referring to standards and regulations in use.  

SCAM T.P.E. S.r.l. package towers are realized by a direct mechanical coupling between engine and fan with the resulting advantage of reducing noise due to transmission organs lack, and the installation of the engine inside the diffuser (apart from the indirect transmission towers type TTP/TTS).

The noise reduction process can be effected in gradual stages of growing soundproofing impact:

• - LOW AND VERY LOW ACOUSTIC EMISSIONS FAN (SCAMAIR-ST or SCAMAIR-SX type) with “NACA” profile, asymmetric, twisted blades or with stretched “elephant ear” profile.

• - HIGH POLARITY ENGINE  in order to reduce spin rate of the impeller in the fan group.

• - SCAMAT ANTI-ROAR OF WATER IN BASIN MAT with PP or PVC panels installed on a bearing frame or floating on the water free surface.

• - INSULATED SOUNDPROOF WALLS (TAS version) sandwich type in polystyrene (22 mm thick) covered by FRP or by plate galvanized and painted with SCAMBOND/HYB cycle;

• - CIRCULAR OUTLET SILENCER SCAM/ GV or SCAM/SV WITHOUT OR WITH OGIVE installed on diffuser (ask for specific technical sheet for further insights)

• - ASPIRATION SOUNDPROOF SEPTUMS SCAM/LVR-ST made up of soundproof, water repellent, anti putrefaction material with a low percentage in water absorption  and possible waterproofing membrane. Septums are supported by a frame in galvanized steel or in aluminum easily removable.

• - VDI SYSTEM inverter with integrated management software to be positioned on tower board and/or in remote location (it is supplied already wired without extra costs for additional control panels) in order to control the impeller speed in the fan vis-à-vis the temperature of the water coming out of the tower. In this way you can take advantage of wet bulb temperature variation during the normal seasonal cycle and in day/night cycle.

In order to optimize these solutions SCAM T.P.E. S.r.l. provided to prepare some soundproofing packages to be implemented on every version of tower as described here below:

• - LN: silenced version with high polarity engine and low acoustical emissions fan 
• - SLN: silenced version LN + SCAMAT fall attenuators in basin  
• - SSLN1: version SLN + expulsion circular silencer
• - SSLN2: version SSLN1 + aspiration septums silencers (without SCAMAT)
• - VDI: option inverter parameterized and wired on tower board or in remote position with isolator in order to vary fan speed basing on the temperature of the water coming out of the tower. 

For further clarifications about this, please contact SCAM T.P.E. S.r.l. offices.

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- Soundproofing systems for cooling towers

- Septums silencers series SCAM/LVR/ST

- Circular silencers series SCAM/SV and SCAM/GV