There is a general need to install a regulating valve at the gas flow detection and control station and at other compressed air related production facilities where different gas pressures and different gas flows pass. And it is these control valves installed in gas pipes that can cause noise pollution to people and the surrounding environment. Therefore, the noise must be reduced and discharged. This important environmental noise reduction effort requires not only the design of new and new plants, but also the production and operation of existing equipment. This article describes a technically feasible KPF self-locking manual balancing valve that is eco-friendly and noise-free. Practice has proved that if the plant design and planning to take the appropriate measures, then solve the noise pollution of chemical companies work is the most effective and most economical. Because factory-designed noise reduction measures are not limited by the technical conditions of "after-effects" (for secondary noise reduction remedies: subject to design constraints, space limitations, etc.) and no additional Expenses. In principle, it is recommended that silent check valves be classified into different levels according to their effectiveness and economy when reducing the impact of noise on the environment and take different measures to deal with them. ■Control of noise from the main source of noise (typically a regulating valve); ■Measures to prevent the spread of noise (secondarily to reduce noise). In order to limit the regulator valve noise, multi-functional silent check valve manufacturer offers a variety of solutions. What kind of programs in the factory design to reduce noise is most effective in practical applications, see the examples described in this article. For those already in the chemical process equipment used in the control valve, you can also use the method described in this article to reduce noise. Only when the technical means of controlling the noise source is no longer technically and economically the best solution for acoustical control techniques is the second set of "operational" options adopted: the control of the spread of noise from the source of noise, the so-called control "Secondary noise source." This method of controlling secondary noise is: ■Pipe silencer ■Pipe insulation ■Solid acoustic coupling ■Shielding or enclosure In order to select economical and efficient measures to reduce noise, the acoustic strength of the noise source at the noise occurrence must be , And most of the sub-sound sources are not the main source of noise, that is, not the regulating valve in the gas pipeline, but the surface of some sound-conducting objects (such as longer pipes and coolers), especially in their The surface area is much larger than the main noise source even more so. Choosing Low Noise Products There are often some false estimates when choosing a low noise product for a new device. Consider the example below, when selecting products for low-noise equipment, each manufacturer should provide its own products at a reasonable price based on the production status of the chemical equipment (see Table 1). Products supplied by each manufacturer that fit the production conditions in Table 1 are also listed at the bottom of Table 1, which shows the differences among the three factory low-noise products. It can be clearly seen from the above data that the noise level of product C in Factory C is 21dB (A) lower than that of Factory A by 17dB (A) lower than that of Factory B. Reduce the noise emitted by the control valve Purposeful measures to reduce the noise on the existing equipment control valve should have some mechanical knowledge. In the control valve, there is a high pressure difference and gas flow rate differences between the high-speed flow control valve and low-speed airflow transition cross-section, there will be a flow vortex, the structure of the vortex flow structure, high and low speed airflow Intersection geometry, size, determines the maximum frequency of sound waves. The level of sound is determined by the method of energy conversion (pressure energy, kinetic energy, heat). The pressure of gas compression ratio, but also cause a certain compression impact, the formation of another noise source. In order to effectively reduce noise, thus using step-by-step decompression method to prevent one-time excessive pressure difference. To give an example of application: In the air conditioning circuit adjustment ball valve before and after the installation of a noise reduction for each muffler board. This porous muffler utilizes a number of effective muffling principles: When the adjustment ball valve is opened, a large channel of the ball valve becomes a plurality of small channels on the front and rear two muffler plates. This will raise the acoustical (wave) power to a higher frequency level. Due to the ring wall expansion noise shielding ring expansion frequency above the muffler panel frequency, thereby reducing the noise of the pipe. On the other hand, the value of the Kvs of the noise figure of the regulating valve is also reduced. Relatively speaking, to achieve the same Kv value must be adjusted to open a larger ball valve. This change in the structure of the ball valve, but also changed the ball valve flow that large, small and small, which will be the main reason for low-frequency noise: eddy current structure to minimize the impact. The airflow through the longer holes in the muffler plate also improves the way the air flow circulates (no turbulent air flow passages). In the previous section, a multi-muffler plate (720,000 Nm3h with a pressure difference of 3.6 bar) Silencer board (500000Nm3 / h, pressure difference 2.9bar) ​​when the test results, the use of porous muffler board, the adjustment of the ball valve pipe measuring surface sound level level reduced by 7dB (A), and the desired low-frequency noise to high Frequency of moving the head has also been achieved. Effective Measures to Prevent Noise Transmission In practice, the problems of noise transmission in pipelines are often overlooked. Although a series of noise insulation measures have been taken on the gas pipelines, the noise levels given in Table 1 have been achieved so that noise problems are not so However, due to the length of the (empty) pipe, the soundproofing is unfavorable (no soundproofed pipe), so that the noise propagating through the air pipe is obviously higher than the noise generated at the regulating valve. To illustrate this problem more clearly, we take a look at a calculation example: noise was measured after using the noise-proof products manufactured by factory C in Table 1, and the test results are shown in Table 2, including: octave band sound level, tube wall Noise, duct noise at 1 m (measured), and duct noise at 100 m. From the data in the table, it can be seen that due to the long suspended overhead air-flow duct, the noise it propagates is significantly higher than the noise generated by the air-flow control valve despite the noise insulation measures. In the case of this example, it is not the best way to solve the problem of enclosing indoor plumbing for sound insulation. Instead, it is a noise-diverting measure that "gives" noise to the building's neighbor. The correct solution is: the installation of pipe silencers in the pipeline after the control valve or installation of pipe isolation device, the size of the pipe silencer is not too large, the cost of using this measure (production costs and maintenance costs) Can not be underestimated, but with this sound insulation measures, sound insulation is very good.
