Analysis of Composite Scrubber with Built-In Silencer for Marine Engines

The International Maritime Organization (IMO) is strengthening regulations on reducing sulfur oxide emissions, and the demand for reducing exhaust noise affecting the environment of ships is also increasing. Various technologies have been developed to satisfy these needs. In this paper, a composite scrubber for ships that can simultaneously reduce sulfur oxide and noise was proposed, and the flow characteristics and noise characteristics were analyzed. For the silencer, vane type and resonate type were applied. In the case of the vane type, the effects of the direction, size, and location of the vane were analyzed, and in the case of the resonate type, the effects of the hole location and the number of holes were analyzed. The result shows that the length increase of the vane increased the average transmission loss and had a great effect, especially in the low frequency region. The transmission loss increased when the vane was installed outside, and the noise reduction effect was excellent when the vane was in the reverse direction. In the resonate type, increasing the number of holes is advantageous for noise reduction. The condition for maximally reducing noise in the range not exceeding 840 Pa, which is 70% of the allowable back pressure, is a vane length of 225 mm in the outer vane reverse type. The pressure drop under this condition was 777 Pa, and the average transmission losses in the low frequency region and the entire frequency region were 43.5 and 54.5 dB, respectively.