Noise-silencing technology for upright venting pipe jet noise

Abstract

When a natural gas transmission and distribution station performs a planned or emergency venting operation, the jet noise produced by the natural gas venting pipe can have an intensity as high as 110 dB, thereby severely affecting the production and living environment. Jet noise produced by venting pipes is a type of aerodynamic noise. This study investigates the mechanism that produces the jet noise and the radiative characteristics of jet noise using a computational fluid dynamics method that combines large eddy simulation with the Ffowcs Williams-Hawkings acoustic analogy theory. The analysis results show that the sound pressure level of jet noise is relatively high, with a maximum level of 115 dB in the low-frequency range (0-1000 Hz), and the sound pressure level is approximately the average level in the frequency range of 1000-4000 Hz. In addition, the maximum and average sound pressure levels of the noise at the same monitoring point both slightly decrease, and the frequency of the occurrence of a maximum sound pressure level decreases as the Mach number at the outlet of the venting pipe increases. An increase in the flow rate can result in a shift from low-frequency to high-frequency noise. Subsequently, this study includes a design of an expansion-chamber muffler that reduces the jet noise produced by venting pipes and an analysis of its effectiveness in reducing noise. The results show that the expansion-chamber muffler designed in this study can effectively reduce jet noise by 10-40 dB and, thus, achieve effective noise prevention and control.

Formation Mechanism of Trailing Oil in Product Oil Pipeline

“…The length between the check valve and the mouth of bypass was 2 m. The pumping station had a 508 mm pipe diameter, and the pipe diameter of the bypass was 168 mm. According to the calculation results, the following batch had flowed through two-thirds of the cross-section of the pipeline in 4 seconds, so we took the volume fraction of the oil at 4 seconds for the grid independence verification and the step independence verification [27,28]. We analyzed the volume fraction of oil in Section 3, which is shown in Figure 3.…”

“…A grid independence verification was conducted for four grid numbers, including 603042, 1532451, 2034861, and 3021581, and a step length independence verification was conducted for four time steps of 0.0005 s, 0.001 s, 0.01 s, and 0.05 s. When the grid number changed from 600,000 to 3 million, the oil volume fraction changed very little with the increase of the grid number, indicating that these four grid numbers had little influence on the calculation results (see Table 2 and Figure 4). According to the calculation results, the following batch had flowed through two-thirds of the cross-section of the pipeline in 4 s, so we took the volume fraction of the oil at 4 s for the grid independence verification and the step independence verification [27,28]. We analyzed the volume fraction of oil in Section 3, which is shown in Figure 3.…”

Flow field and noise characteristics of manifold in natural gas transportation station

“…Tan and Wang analyzed the velocity field in downstream gas pipe of manifold and obtained the reasonable velocity field distribution [19]. Liu et al did several aggressive studies on aerodynamic noise, which included the analysis of the factors influence the noise of upright venting pipes, elbows and manifolds [20][21][22][23].…”

Steady-state optimization operation of the west–east gas pipeline

“…However, this is very difficult to achieve, because more gas requires higher pressure and more compressor energy consumption and creates greater flow noise. 1,2,3 For a long gas pipeline, the main expense is the running cost of the compressor stations. Studies have shown that the energy consumption of the compressors is more than 50% of the total energy consumption of a pipeline.…”