Valve World Magazine August 2023 | Page 41

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High-pressure recovery valves ( see Figure 1 ), have been used for quite a number of years as fuel control devices to regulate gas flowing to burners of gas-turbine generators . Such valves bring significant benefits . For example , the most important feature of this valve is the great energy savings it offers . The device can control large amounts of liquids or gases whilst sacrificing only limited amounts of pressure drop – just 10 per cent of inlet pressure for gases , for example . Also of interest is the unique function of this device to be able to operate within a significant range of pressure reductions and within a laminar flow regime . This flow regime experiences no turbulence , nor the associated sound . The question arises , why hasn ’ t this concept been employed in general industry ? The answer may simply be a lack of familiarity . In order to provide a viable alternative for general use , the author has therefore designed a special valve type as shown in Figure 2 .

Control valves

The advantages of high-pressure recovery control valves

Widely applied and appreciated in gas turbine use , highpressure recovery control valves have however yet to make any real inroads in other applications . In his latest article , control valve expert Hans
Baumann explains the function , test results , and advantages of this valve concept which , he believes , could be of real benefit in other industrial sectors .
By Hans D . Baumann
Description of the device
As Figure 2 shows , the design is quite simple and lends itself to low-cost manufacturing . There are only three moving parts . The appearance draws itself to a butterfly valve . Yet , this vane does not close in the
Fig . 1 : Design of a high-pressure recovery control valve
vertical direction , but is tilted about 30 degrees from the horizontal axis . Significantly , in this position , all side surfaces along the vertical axis are in contact with the inner wall of the housing in order to provide shut-off , thus providing a tilted wall across the housing ( see also the vertical view in Figure 2 ). The reason for tilting the vane is to provide an overall length which is twice that of a comparable vertical vane . The result is that all planar surfaces are located less than 20 degrees ( α ) from the vertical axis , thus providing sufficient pressure recovery . Unfortunately , nothing is perfect . In this case , the device cannot meet Class IV leakage ( although it will meet Class II ). In addition , the travel is limited to 30 degrees . This means that the shaft will need a 2 ” extended lever to satisfy 1 ” actuator travel . On the other hand , with such high leverage and low
About the author Dr . Baumann , a former President of the Baumann valve company and a former VP of Masoneilan and Fisher Controls , is now an international consultant . He is credited with 106 US patents and has authored 140 publications and eight books , including the Control Valve Primer now in its fifth edition . Dr . Baumann is an Honorary Member of ISA and a Fellow Member of ASME . He can be reached at hdbaumann @ phbinc . net .
Fig . 2 : Author ’ s design of a high-pressure recovery control valve - patent applied for

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