Pulsation damper

Fig. 1. Flow diagram of production of sulfur dioxide from oleum 1, 30% oleum exchanger 2, SO vaporizer 3, reactor 4, coolant surge tank 5, coolant ckculatkig pump 6, coolant exchangers 7, sludge and acid pump 8, scmbber 9, SO2 cooler 10, gas cleaner 11, SO2 compressor 12, pulsation damper and 13, SO2 condenser. CM is the condensate FRC, flow recording controller PIC, pressure kidicatkig controller SM, steam TC, temperature recorder ...

When the pulsation amplitude is such as to result in a greater-than-permissible metering error, consideration should be given to installation of a pulsation damper between the source of pulsations and the flowmeter. References to methods of pulsation-damper design are given in the subsection Unsteady-State Behavior. ... 

Flow Low mass flow indicated. Mass flow error. Transmitter zero shift. Measurement is high. Measurement error. Liquid droplets in gas. Static pressure change in gas. Free water in fluid. Pulsation in flow. Non-standard pipe runs. Install demister upstream heat gas upstream of sensor. Add pressure recording pen. Mount transmitter above taps. Add process pulsation damper. Estimate limits of error. 

Clean the pipework regularly so that deposits do not get more than A in. (3 mm) thick. One fire occurred in a compressor on which it was impossible to clean the pulsation dampers. 

Reciprocating compressors deliver a pulsating flow of gas that can damage downstream equipment or machinery. This is sometimes a disadvantage, but pulsation dampers can be used to alleviate the problem. 

In all cases, to achieve a proper regulation of the flow, a pulsation damper is used. It operates on the principle of a mechanical ballast or can be electronically controlled. The simplest mechanical ballasting device is a coil with a low cross-section, several metres in length, placed between the pump and the injector. Under the influence of a wave of solvent, the tube uncoils slightly which increases its internal volume and dampens the variation in pressure. 

Most of the high pressure vessels as used for reactors, scrubbers, heat exchangers, buffer vessels or pulsation dampers, are mainly consisting of hollow cylinders. 

Rotary pumps deliver a nearly constant flow at a given speed, regardless of the pressure. Bypass control is the usual method, with speed control in larger sizes. Reciprocating pumps also may be controlled on bypass if a pulsation damper is provided in the circuit to smooth out pressure fluctuations Figure 3.21(c) shows this mode. 

Pumps us l to pull air through cyclones and elutriators should be steady and free from pulsed flow A pulsed flow tends to collect a higher mass of respirable dust. Pulsation dampers are available which reduce the pulsation to an acceptable level. 

Samples collected should be full shift (at least 7-hour) samples. Sampling should be done using a personal sampling pump with pulsation damper at a flow rate of 2 liters per minute. Samples should be collected on 0.8 micrometer pore size silver membrane filters (37 mm diameter) preceded by Gelman glass fiber type A-E filters encased in three-piece plastic (polystyrene) field monitor cassettes. The cassette face cap should be on and the plug removed. The rotameter should be checked every hour to ensure that proper flow rates are maintained. 

Fig. 6.32 Pulsation damper with perforated plate and hydro-pneumatic tank (source Voith).

Process machines installed upstream of the headbox, for instance the fan pump or the screen, generate pulsations which may be higher than allowed (for instance less than 1% deviation). In such a case a pulsation damper reducing pulsations over a wide frequency range should be installed ahead of the distributor of the headbox or integrated into the headbox. Figure 6.32 shows an example of such a... 

For small feed rates, it may be considerably cheaper to use a positive-displacement pump (piston type). Control may be by stroke adjustment on a constant-speed pump as shown by Figure 5.2A or by adjustment of a variable-speed drive of a pump with a fixed stroke as shown by Figure 5.2B. If the minimum stroke rate is at least three times the reciprocal of the feed-tray holdup time, no pulsation damper is required. 

Figure 11.13 (a) Cross section ofa 21 high-pressure pulsation damper (source Uhde High Pressure... 

A pulsation damper is required at pump discharge to damp the pulsation flow from the racipfocatiqg pump. A pulsation damper or stabilizer is sometimes used at pomp suction to increase its NPSHA. 

L equals 1S ft, if a pulsation damper is installed at suction piping. [3]... 

Figure 13 Approximate pulsation damper sizing chart, [5J...

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