Last Updated on March 6, 2023 by Hassan Abbas
Modern power stations, the necessity to ensure that systems are depressurized safely and release steam is crucial for a safe operation. The speed at which steam is released can create immense noise pollution. This can pose a risk for workers as well as the surroundings. To lower the level of noise the majority of power plants have vent silencers. Therefore, knowing the the working principles of a vent silenceris essential to making sure workers are protected.
What Are Vent Silencers?
Vent silencers, also referred to in the same way as blow off silencers are equipment that industrial and power plants employ to reduce noise levels. Noise is the result of discharging steam flow gas directly from a pipeline into the air. Because of the speed of gas flowing through the valve turbulence it produces noise. This is why engineers and managers need to take action to stop this noise from creating dangerous conditions for employees or the surroundings.
The Vent Silencer Working Principles
Vent silencersfor industrial steam vents cut down on noise by utilizing two fundamental principle to cover a greater frequency range. Vents make use of active components that reflect sounds towards the source instead of exchanging the sound. When the sound travels, the volume decreases and it dampens. A lot of silencers feature absorptive or dissipative materials to lower the volume of sound. Depending on the thickness the materials function as a barrier, taking in the sound before releasing it into the surrounding space.
Where to Install the Vent Silencers
In many venting systems the primary cause of sound pollution is from the stack’s open exit. Certain designs of plants place the silencer on the outlet of the stack. For the best use of the silencer for a steam vent, it is recommended to install the vent in the stack. By putting the vent within the stack, it will absorb the sound before dispersing out into the atmosphere.
A vent silencers or diesel exhaust silencer, is an instrument that’s used to minimize the noise generated by steam or gas in a pipeline that discharges directly into the air. This kind of noise is by the high-speed flow through the valve , and the turbulence generated around any obstacle within the pipeline that abruptly blocks or alters the direction of flow , such as an orifice or a valve.
Vent Silencers are used in steam vents and safety vents for relief valves, systems blow downs , purge outlets, etc. The sound level of the blow down or vent is the result of the upstream pressure and temperature and the gas type being vented, the size of the valve and design, and also the effects of the downstream pipe. The Vent Silencers are designed to limit the level of noise to the desired noise level at a certain location from where the silencer. This is why silencers that vent and blow down are not a standard choice. The information provided here should be taken as a general guideline. Get in touch with our knowledgeable engineers to suggest a silencer that is best suitable for your needs for horizontal or vertical installations.
In any gas venting blow off system, the first release of energy is at the exit of the stack. A Diesel Exhaust Silencercan be placed in the stack or near the stack outlet to block this sound before it is released out into the surrounding. There are two basic principles of noise reduction that are utilized in the design of passive silencers. Dissipative components (using the sound-absorbing material) offer a balanced reduction in noise across a wide frequency range. Reactive components that make use of resonances in chambers and passages that are tuned that reduce noise within a specific frequency range.
Data Required To Select Vent Silencer
- Application (Vent Blow down Relief)
- Fluid Composition (Steam, Gas, Air)
- Molecular Weight or Specific Gravity
- The conditions of the process that are upstream of the valves or the units (lb/hr, SCFM ACFM) Temperature Pressure (P 1)
- The atmospheric pressure ( P ) as well as Temperature (T 2) when they are you know.
- The size of the line between the valve and silencer
- Line size derived from silencer discharge
- Noise levels in the octave band that are not silenced,
- Attenuation is needed (silencer performance)
- Allowable pressure drop
Sizing Of A Vent Silencer
Examples of how to size vent silencer is expert’s work. The size of a silencer is dependent on the flow rate of the gas that it is able to pass through without damaging the acoustical pack or generating noise. The length of the silencer is dependent on the amount of noise reduction attained.
More About Vent Silencer
It is the vent silencers can be suitable to minimize noise created by the release of high pressure gases or steam into the air. Silencers are of a reactive absorptive or reactive design. The noise and gas enter through the single or multi stage diffuser. There it can expand through a number of small holes to an expansion chamber. The diffuser’s design and the size of the expansion chamber create an optimum reacting section. The diffuser is also able to provide the ability to shift frequency to higher frequencies, which is best reduced through the absorptive section.
The gas then flows through the absorptive portion which is comprised of several perforated flow tubes , surrounded by acoustical acoustic packing dense enough to provide an array of attenuation from the mid – to high-frequency ranges. The most common construction is a strong carbon steel shell that is all welded assembly including flow tube bundles and diffuser inlet with acoustical packing made of long strand fiberglass, suitable for the temperatures that are that are indicated. The length of the flow tubes and the amount of bundles are dependent on the level of silencing that is required. The silencer’s thickness is one-quarter” corrosion allowance, and is finished with rust inhibitory primer. Other options include numerous inlets, different materials or finishes mount brackets, and codes.
Design and Installation:
In the standard gas or steam venting systems the release of sound energy usually occurs near the vents. Therefore the vent silencer must be located near the outlet of the stack or inside the stack to block and eliminate the noise before it is able to escape into the surrounding environment.
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