Torsion Vibration Measurement and Analysis of Flue Gas Fan

Torsion Vibration Measurement and Analysis of Flue Gas Fan Torsion vibration can influence the operability and technical life of drive systems such as fan-motors or automatic trains. Typically, torsion vibration is weakly coupled (in the XYZ direction) with axial vibration when the drive system is straight. It can be nearly impossible to detect torsion vibration from axial vibration measurement because of this weak coupling. This section discusses various ways to detect the presence of torsion vibration and how to quantify torsion vibration when troubleshooting. The phrase torsion vibration...

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Piping Vibration Fatigue Risk Assessment

Vibration is not really what we want to thoroughly assess piping vibration risk –we should instead use mechanical stress range and load cycles to estimate the risk for vibration fatigue. There is an established methodology where mechanical stress range is assessed with respect to fatigue risk with the help of so called SN-data, where S signifies Stress range (Pk-Pk) and N is the Number of load cycles. A combination of stress ranges and load cycles can be added together using Miner’s rule to assess fatigue risk and estimate a pipe’s lifetime. Link Given this, why do we measure...

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Flow Induced Noise

To design robust process industry systems that are insensitive to flow induced pulsation, one must first understand the aeroacoustic mechanisms involved, which can be come rather heavy on theory. Perhaps a simpler way is to understand how wind instruments generate sound and then simply avoid replicating these mechanisms in process equipment? Most people know that blowing across the edge of a bottle produces a tone and many people may have noticed that the masts and wires of a sailboat sing. The phenomena that make up the above observations are referred to as flow acoustics, aeroacoustics or...

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Pulsation Measurement

Correctly measuring pulsation is more difficult than it seems. As mentioned elsewhere (Link), Pressure = LinePressure + Kinetic Pressure + Pulsation. Line Pressure (LP) usually is measured without much problem. LP can be affected by Pulsation when long tubing leads to the pressure sensor (see Figure 1). Industry-type pressure sensors tend to be placed on a small bore fitting, often with a blocking valve situated between the pressure sensor and the flange (see Figure 1- flange not shown). This setup works for Line Pressure and suppresses Kinetic Pressure, but is less ideal for pulsation...

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Reciprocating Pumps Pulsation Signature

Reciprocating pumps emit strong pulsation when there is no pulsation countermeasure. Reducing pulsation saves not only pump wear but also piping fatigue life. Reciprocating pumps use a reciprocating piston to displace fluid volume. Inlet flow is controlled by a passive valve, i.e. a springloaded valve that opens when the piston expands the cylinder’s volume (see Figure 1). The discharge valve is closed during the suction stroke. The discharge valve is opened when the piston decreases the cylinder’s volume.The suction valve is closed during this compression stroke. (A) (B) Figure 1. A) The...

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Emergency Generators

Reserve power, e.g. emergency diesel generators, are not units intended for continuous operation, but rather systems tasked with vital safety functions. To ensure this system safety function, these systems are tested for a specified period of time at regular time intervals; say, a few hours every two weeks. A common problem for these types of units is that their heaviest components, the motor and the generator, rest on weak skids and frames. Industry-sized generators emit a fair amount of structure-borne noise and can become a potential noise source when located near offices and living...

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