yongda xing mechanical and electrical equipment:Noise treatment method of diesel generator set-24 hours free hotline Li Sheng →400-6088-009-13902465009] QQ:406256032

Abstract: A noise reconstruction project of high-power diesel generator in a narrow space is introduced. Through the transformation of the original machine room, increase sound insulation, sound absorption, ventilation and other measures, so that the generator noise emission standards.
1 Introduction
IBM company is located in Shenzhen Futian Free Trade Zone, the company's plant has a Cummins-Onan DFLC 1 120KW diesel generator set. The original generator noise control project was undertaken by a company in Hong Kong, and the noise value at 3m outside the machine room was 62.7dB(A). Because the generator noise has exceeded the standard, the project needs to be rebuilt to meet the national standard GB3097-93 Class II area standard, that is, the noise value during the day is ≤ 60 dB(A), and the noise value at night is ≤ 60 dB(A).
2 Noise sources
The noise of diesel generator set mainly includes intake and exhaust noise, combustion noise and mechanical noise generated by moving parts. When the unit is in operation (no load), the noise value in the room (measuring point 1) is 105.2 dB(A), the noise value at 3m away from the exhaust louver (measuring point 2) after the original treatment is 65.8 dB(A), and the noise value at 1m outside the factory boundary (measuring point 3) is 62.7 dB(A).
The internal and external transmission paths of noise in the machine room include the air inlet of the machine room, the air exhaust of the unit, the smoke exhaust pipe, the door of the machine room, etc.
Due to the high sound pressure of the noise source and the small area of the machine room, it must be transformed on the original basis, so it is difficult.
3 Original noise control measures
3.1 sound insulation room
The sound insulation room is installed at the generator position, with a size of 8.0m × 3.0m × 3.5m. The sound insulation room adopts [10 channel steel as the bracket, and the sound insulation board with a thickness of 100mm is applied. The outer wall of the sound insulation board is 1.2mm galvanized sheet. The inner wall is 0.8mm perforated plate (aperture Φ3, opening rate 20%), the middle filler is 32kg/m3 ultra-fine glass wool, and the concave surface of the channel steel is filled with glass wool.
3.2 exhaust silencing
The generator relies on its own fan for exhaust air. AES rectangular muffler is installed in the front of the exhaust room. The size of the muffler is 1.2m × 1.1m × 0.9m. The muffler is equipped with a thickness of 200mm and a spacing of 100mm. The muffler adopts the structure of galvanized perforated plate with ultra-fine glass wool on both sides. Nine mufflers of the same size are assembled into a large muffler of 1.2m × 3.3m × 2.7m. Exhaust louvers of the same size 300mm in front of the muffler.
3.3 inlet silencing
Install natural intake muffler at the top of the sound insulation room. The muffler is made of the same exhaust muffler, with a net muffler length of 1.0m, a cross-sectional dimension of 3.4m × 2.0m, a thickness of 200mm and a spacing of 200mm. The muffler is externally connected with an unlined 90 ° muffler elbow, and the muffler elbow is 1.2m long.
3.4 smoke elimination
Through the two residential mufflers matched with the original generator, the muffed smoke is merged into a Φ450mm smoke pipe protruding from the exhaust louver and discharged upward.
4 Advantages and Disadvantages of Original Treatment Measures
4.1 advantages
(1) The exhaust air of the generator radiator is discharged directly to the outside without elbows, the resistance loss is small about 172Pa, and the power loss is small. P = ερu2/2
In the formula, P-pressure loss;
U-u-6.7 m/s;
ε-resistance coefficient, taking 6.440;
ρ-air density, taking 1.2.
(2) The exhaust smoke muffler adopts a residential muffler, the exhaust back pressure is small, the generator has high combustion efficiency and low power loss.
4.2 Disadvantages
(1) The machine room adopts natural air intake, and the air intake area is small (3.4 m2), so the machine room generates large negative pressure, which is difficult to meet the requirements of generator combustion and heat dissipation.
(2) The sound insulation value of the sound insulation room is low, the connection between the channel steel and the sound insulation board is poorly sealed, and the noise value at 0.5m outside the sound insulation room (measuring point 4) is 86.3dB(A).
(3) The exhaust noise is large, and the noise reduction distance is too short to produce this problem.
(4) The exhaust noise is large, and the residential muffler can only attenuate the noise value of 25dB(A) at most.
5 Governance and transformation measures
The reconstruction project must maintain the original machine room structure as much as possible, so the initial reconstruction measures are as follows:
(1) Increase the thickness of the sound insulation wall of the sound insulation room.
(2) The exhaust silencing distance is lengthened, and 300mm thick silencing louver is installed at the same time.
(3) Installation of 300mm thick inlet air silencing louver shall be added.
(4) increase the installation of forced air intake fan.
(5) the smoke exhaust system to increase the installation of three expansion chamber muffler.
After consultation with Party A, Party A believes that the silencing louver has changed the appearance of the machine room, so the air inlet and exhaust silencing louver cannot be installed. After the final discussion, the transformation scheme is determined as follows:
(1) The thickness of the sound insulation wall of the sound insulation room is increased by 50mm in two directions close to the outer door of the sound insulation room. First, use ∠ 50 angle iron to stick the original sound insulation wall to install the skeleton, then fill 32kg/m3 ultra-fine glass wool, the outer panel is 1.2mm galvanized sheet, all joints are sealed with glass glue, and the joints are staggered with the original channel steel joints.
(2) The sound insulation performance of the door of the original sound insulation room is poor. In order to prevent noise leakage, felt seal is used between the doorway and the door frame.
(3) Due to the short sound elimination distance of the exhaust air, the exhaust room is changed to: a partition wall with a thickness of 3.3m, a length of 4.3m and a height of 0.2m is set 2m away from the exhaust outlet of the generator, and the exhaust air of the combined generator moves upward, and then discharges downward from the original louver after sound elimination. The main body of the partition wall is 6mm thick steel plate, both sides are coated with 100mm thick 32kg/m3 ultra-fine glass wool, and 1.2mm thick galvanized perforated plate is used as the protective surface. The exhaust turning part is made into an air guide groove with large curvature (the air guide groove panel is a 1.2mm thick galvanized perforated plate filled with 2kg/m3 ultra-fine glass wool) to minimize the wind resistance and make the exhaust smooth.
(4) Add a forced air intake fan on the inside side of the machine room, and install a muffler elbow and AES muffler (effective muffler length 1.6m). The intake air volume is 30000 m3/h, and the wind speed passing through the muffler is controlled to be ≤ 6 m/s, so that no secondary noise is generated. At the same time, the wind speed through the original natural intake muffler is reduced to 4.32 m/s, and the muffling effect will be better than before.
(5) A three-stage expansion chamber muffler is added to the smoke exhaust system, and the two smoke pipes are led to the outdoor for emission to avoid turbulent noise.
(6) Shock absorption measures. Because the base of the original generator was installed with JP rubber vibration isolation pad, the shock absorption work is mainly placed on the smoke exhaust pipe and the smoke exhaust muffler. The smoke pipe and the muffler are both mounted on the roof of the sound insulation house with DJ type shock absorption hanger to reduce the transmission of low frequency noise.
6 Conclusions
High-power diesel generator sets have high noise value and large calorific value. Without affecting the power of the unit, reducing noise and ventilation and heat dissipation are the key to noise control projects. Through the above measures, we have basically eliminated the noise pollution of the generator set.
During the acceptance of the project, the noise value at 1m outside the factory boundary was 49.8dB(A) at 11:30 p. m. by the municipal environmental protection monitoring station, which reached the class ii zone standard in the national standard GB3097-93. therefore, the noise control and renovation project was successful.
[Contact: Li Sheng 24-hour free hotline →400-6088-009-13902465009] QQ:406256032