Absorbing silencers
These silencers work according to the principle of absorbing sound with the aid of an absorbent lining inside the silencer. They usually provide silencing over a broad frequency range. They are generally of straight-through construction and only offer a marginally higher back pressure than a straight pipe of the same length.
Expansion silencers (reactive)
These silencers work according to the principle of reflecting and holding it inside the silencer. The silencer has internal baffle plates that divide it up into sections. A reactive silencer creates a relatively high pressure back to the middle of the gas flow, ie the baffles that redirect the flow. Volvo Penta HD silencers combine reactive and absorbing silencing. Silencer location Reactive silencers are located as close as possible to the exhaust manifold as possible (to impede sound from the manifold) or at the end of the system. There must only be a short end pipe ( ≈1 m) after the silencer if it is installed at the end of the exhaust line. Insulation of long exhaust lines affects exhaust pressure.
Exhaust System of Volvo Penta Engine Generator
The exhaust system must be planned from the beginning of the installation.
The main objectives are to:
The entire limit is set by the engine manufacturer.
B reduce strain on the manifold and turbocharger by supporting the system.
Provide space in the correct direction for heat expansion and contraction.
D provide flexibility if the engine is fitted with vibration damping mounts.
E reduce exhaust noise. The illustration on the right shows a typical installation.
Multiple Exhaust Outlets
IMPORTANT!
Exhaust gases from multi-engine installations may not be used together in a common system. The reason for this is that the engine is at rest during the other is running, exhaust gas, condensate and soot wants to be put into the resting engine exhaust system and into the cylinders, which may cause corrosion. If a good quality butterfly valve is installed, it may be exhausted. Use the following formula for calculating the total diameter of the common exhaust pipe:
DTOTAL = D x K
D = exhaust pipe diameter for one engine.
K = factor (refer to the table).
Number of engines
Back pressure
The exhaust system wants to give a certain resistance to exhaust gas flow. This resistance must be kept within given limits.
Excessive back pressure causes:
- Loss of power
- Poor fuel economy
- High exhaust temperature
Search conditions will cause overheating and excessive engine smoke, and want to reduce and turbocharger service life. Maximum permissible engine pressure values for Volvo Penta engines are specified in the Sales Support Tool, Partner Network.
A manometer is used to measure exhaust pressure at maximum rated power.
It may be difficult to use a flange in many installations because of a lack of space. 2 mm (0.08 ") and located on a straight pipe section The distance from the hole to pipe bends and tapered sections must be at least 100 mm (4 ").
Calculation of Back Pressure
Calculation of back pressure for HD silencers For the purpose of calculating back pressure on Volvo Penta silencers exhaust gases and temperatures are specified in an Excel-based system in the Sales Support Tool, Partner Network.
NOTICE! The application for cooling exhaust system is based on a worst case. This means that the exhaust is not exhaustive. The calculation application is thus based on a pipe system with a radius of 2.5 times the pipe diameter. Silencer back pressure used in the application is only applicable to Nelson-Burgess DDA type silencers. These silencers are described with HD in the Industrial Sales Guide.
installation
Flexible connection pipes
The exhaust pipe is isolated from the engine with flexible connection pipes. The flexible connection pipes are located close to the exhaust and have three functions:
1 Isolating vibration and exhaust pipe weight from the engine.
2 Compensating exhaust pipe expansion.
3 Compensating sideways motion when the engine starts or stops when the engine is attached to vibration dampening mounts.
The flexible pipe is capable of absorbing small radial movements, but no twisting or axial movements.
The flexible unit can be installed in different positions.
In the calculations, consideration must be given to exhaust pipe heat expansion to avoid excessive strain on the supporting structure.
For each temperature increase of 100 ° C (212 ° F) one meter of steel pipe will expand to 1.2mm (0.047 ") .It is important to locate the holders Furthermore, equipment must be removed without additional support.
Long pipes are divided into sections using expansion joints. Each section is fixed at one end and is able to expand at the other.
Condensate drainage
Any rainwater or condensate that gets into the engine can cause great damage. Long exhaust lines must therefore be equipped with water drainage as close as possible to the generator set engine.
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