Pulsation dampeners

Space needs to be provided for the auxiliaries, including the lube oil and seal systems, lube oil cooler, intercoolers, and pulsation dampeners. A control panel or console is usually provided as part of the local console. This panel contains instmments that provide the necessary information for start-up and shutdown, and should also include warning and trouble lights. Access must be provided for motor repair and ultimate replacement needs to be considered. If a steam turbine is used, a surface condenser is probably required with a vacuum system to increase the efficiency. AH these additional systems need to be considered in the layout and spacing. In addition, room for pulsation dampeners required between stages has to be included. Aftercoolers may also be required with knockout dmms. Reference 8 describes the requirements of compressor layouts and provides many useful piping hints. 

Software packages are commercially available for simulation of hydrauhc transients. These may be used to analyze piping systems to reveal unsatisfactoi y behavior, and they aUow the assessment of design changes such as increases in pipe-wall thickness, changes in valve actuation, and addition of check valves, surge tanks, and pulsation dampeners. 

Pulsation dampeners or intake or diseharge sileneers to be supplied. 

Lubricated cylinders use a separate mechanical lubricator to force feed, in metered droplet form, a very precise amount of lubricant to specified points. This minimizes the amount of lubricant in the cylinder and allows a lubricant most compatible with the gas to be selected without compromising the frame lubrication system. Lubricant is fed to a point or points on the cylinder to service the piston rings and the packing when required. In a few cases, as in air compressors, the packing is lubricated from the crankcase. On some applications involving wet CO7 or H2S m the gas stream, special materials may be avoided if one of the lubrication points IS connected to the suction pulsation dampener. 

Pipe length from scrubber to suction pulsation dampeners... 

Pipe length from discharge pulsation dampeners to cooler... 

A pulsation dampener is an acoustic filter designed for minimum transmission of all the frequencies generated as... 

In many instances, the design of suction and discharge pulsation dampening drums (or bottles) for reciprocating compressors is based on piston displacement and volumetric efficiency, and this design normally will suffice to reduce peak pulsation to approximately 5% of the line pressure. In special or other cases, experience has shown that operational difficulties (vibrations, meter pulsations, etc.) may indicate that the peak pulse pressure of 5% line pressure is inadequate. Thus, the pressure in pulsation-reduction design selection is... 

Example 13-3. Sizing a Pulsation Dampener Using Acoustic Method... 

To size a pulsation dampener so that vibrations may be held to a very minimum (size dampener for discharge side only for this example) ... 

The pulsation dampener must be capable of filtering the base frequency, or 10, 20, 30, 40 cycles/sec based on the rated speed, with a cut-off frequency at least one cycle/sec below the low speed frequency (8.67 cycles/sec). 

Newman, C., and N. H. Moerke, Which Type of Pulsation Dampener Fits Your Compressor Problem Petroleum Processing. 1,724, Nov. (1955). 

Pulsation Dampener or Smge Drmn, 581 Common Design Terminology, 582 Applications, 585 Internal Details, 591 Design Method — Smge Drirnis (Nonacoustic), 591 Single-Compression... 

A poorly designed discharge manifold can cause shock waves and excessive pressure peaks. This manifold should be as short and direct as possible, avoiding any sharps turns. The conventional small atmospheric air chamber, often furnished with pumps, supplies only a moderate cushioning effect. For best results, this air chamber should be supplemented by a large atmospheric air chamber or by a precharged pulsation dampener. 

Pressure spikes measured before and after a pulsation dampener... 

In particular, vibrations and pulsations due to positive-displacement compressors can cause premature opening when the forces within the valve are anywhere near equilibrium and are acting as another upward force. For pilot-operated valves, some manufacturers provide pulsation dampeners in their pressure pick up lines so that the effect of these pressure spikes are compensated. As can be seen in Figure 6.21, for spring-operated SRVs, unfortunately, no provisions can be taken to compensate for this effect. 

Use centrifugal pumps. If positive displacement pumps must be used, these pumps must be fitted with approved pulsation dampening equipment surge tanks may also be required, particularly for very short and very long pipe runs. 

This paper summarizes different methods of pulsation dampening in high pressure plants, and shows how to control and optimize the effectiveness of damping measures by numerical pulsation analysis. 

Pulsation dampeners work by fluid friction, reflexion of pressure waves and volume elasticity. They represent an effective measure of controlling pulsation. 

Especially on the discharge side of pumps pulsation dampeners are very expensive. For that reason the attempt to manage pulsation without dampeners is often made. That is sometimes possible, if other kinds of dampening mechanisms can be used. 

In the example below a numerical pulsation study was performed to control the effectiveness of the pulsation dampening devices. 

Vetter, G., Seidl, B. Pressure Pulsation Dampening Methods for Reciprocating Pumps. Proc. 10th Int Pump Users Symp., Houston TX, USA 1993, 25-39. 

To further minimize possible pressure pulsation, the pumps can be installed together with a pulsation dampener mounted at the discharge. Pulsation dampeners are air pressurized or spring loaded to ensure a smoother product flow in the process line. Slow rotational speed of the pump s crankshaft also helps to minimize pressure pulsation. 

Relief Valves/Pulsation Dampeners (Volume Bottles)/Inter-Connecting Piping/InitiaT ... 

---