Segmented ball valves are designed to control gas, steam, liquids, and fibrous slurries. A common problem associated with a control valve is the high noise it generates while reducing the pressure from upstream to downstream pressure as required by the process conditions. Cavitation is also a problem. Prior segmented ball valves have been equipped with features to reduce noise and cavitation during operation.
Segmented ball valves are commonly used control valves for various liquids and gases which generates high noise in the process. Noise is reduced by introducing noise attenuators on the segment which distributes the pressure drop into multiple stages and absorbs energy thereby reducing the noise. The valve is operated by positioning the segment at the required opening to attain a particular process condition. The noise attenuator on the segment provides maximum restriction at lower openings working at high pressure drops and least restriction at higher openings working at low pressure drops.
Cavitation is a liquid phenomenon of formation of vapor bubbles where the pressure of the liquid falls below its vapor pressure and collapsing of these bubbles in the higher-pressure region. Cavitation too often produces high level noise and vibration.
Segmented ball valves have a single piece body construction. During assembly, the segment which is larger than the body bore requires to be aligned in a particular orientation to insert through the body downstream bore and rotated inside the body spherical cavity to the correct position. The noise attenuators welded on to the segment further increases the segment's overall size which makes it difficult to assemble into the body. This limits the number and size of the plates used in the noise attenuator resulting in low performance of the attenuator. Furthermore, any change required in the noise attenuator design at site resulting from change in process conditions would require replacing the entire segment which requires re-doing the hydro seat test.
Typical noise attenuators use straight plates welded on to the segment which does not create an expanding flow or non-impinging jet streams in its flow profile. This results in poor noise attenuation.
Segmented ball valves have one of the highest valve style modifier values (Fd) resulting in higher calculated noise as per IEC-60534-8-3. This results from a single opening type flow path compared to two or more flow paths in other types of valves which makes it the least preferred valve type for high noise applications. Lowering or reducing the Fd value is desirable.
The industry demands a solution which can reduce the noise effectively utilizing a lower Fd and greater number of pressure-reducing stages with non-impinging jet streams and provide the flexibility to change-out noise attenuators at site easily.
Improvements to lessen cavitation in the interior of the valve body and in the segmented ball of the segmented ball valve are also desirable.
Exemplary embodiments disclosed herein relate to various features in the segmented ball valves to reduce noise and cavitation more efficiently and provide the flexibility to replace the noise reducing features within the valve at site with minimum effort.
The solution utilizes flat segment front profile with a precision machined cylindrical bore on the back side of the segmented ball to fit-in the replaceable low noise and anti-cavitation cartridge. The cartridge is made of curved plates with concave surfaces facing the flow in low-noise applications. For anti-cavitation applications, the convex surfaces of the curved plates of the cartridge would be facing the flow.
In a segmented ball valve designed for low noise and anti-cavitation applications, a replaceable low noise and anti-cavitation cartridge is fixed inside the segment retained by stem and end post. The segment has a machined cylindrical bore with a slide-fit noise cartridge. This enables field replaceability of the noise cartridge on site with minor effort & without need of any welding or fasteners. The replaceable cartridge also enables use of fully cylindrical cartridge with a greater number of pressure reduction stages compared to design with welded on noise plates on the segment. The segment has a flattened front face resulting in lower Fd enabled by dual flow path in lower openings values thereby attaining higher noise attenuation in cases where the noise cartridge is not required. The low noise and anti-cavitation cartridge has curved plates which enables expanding flow resulting in non-impinging jet streams thereby achieving higher noise attenuation. The cartridge enables converging the flow in the opposite direction resulting in reduction of flow energy, thus reducing the potential for cavitation in case of liquids and other media flow.
The embodiments may be better understood, and numerous objects, features, and advantages made apparent to those skilled in the art by referencing the accompanying drawings. These drawings are used to illustrate only typical embodiments of this disclosure, and are not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness.
The description that follows includes exemplary apparatus, methods, techniques, and instruction sequences that embody techniques of the inventive subject matter. However, it is understood that the described embodiments may be practiced without these specific details.
The segmented rotary control valve 10 may have a valve body 18, a segmented ball 20, a valve seat 22, upper valve stem 24a and lower valve stem 24b, and two connector ends 26a, 26b. Connector end 26a defines a relatively smaller diameter opening 26c to the valve body 18, and consequently flow path 30, relative to connector end 26b which defines a relatively larger diameter opening 26d to the valve body 18 and consequently flow path 30.
As mentioned, the segmented ball 20 is shown in the closed position in
The segmented ball 20 includes a flat segment front profile 40 that is facing or opposing the upstream flow path 12a when the segmented ball 20 is in the closed position when using for low noise purposes. When using the segmented ball 20 for anti-cavitation purposes, the flat segment front profile 40 faces or opposes the downstream flow path 16b. The segmented ball 20 defines an internal hollow, chamber, or cavity such as a precision machined cylindrical bore 42 on the back side 44 of the segmented ball 20. The internal cavity 42 is adapted for receiving or to fit-in a replaceable low noise and anti-cavitation cartridge 50 within the segmented ball 20. The cavity 42 passes entirely through the segmented ball 20.
The low noise and anti-cavitation cartridge 50 is made of curved plates 52, 54, and 56 mounted or interconnected in a cartridge body 62 in the exemplary embodiment shown. The cartridge body 62 may be unitary, integral, or of one piece with the curved plates 52, 54, and 56. The cartridge body 62 may, in certain exemplary embodiments, be fabricated together or simultaneously with the curved plates 52, 54, 56. The curved plates 52, 54, and 56 mounted or interconnected with the concave surfaces, respectably 52a, 54a, and 56a facing the flow 12a, 16a, in low noise usages. For anti-cavitation usage, the convex surfaces 52b, 54b, 56b which are mounted or interconnected with the curved plates 52, 54, & 56, respectively, will be facing the flow 12b, 16b. The low noise and anti-cavitation cartridge 50 as mentioned is replaceable in the internal passage 42.
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A better flow profile (i.e. more gradual pressure drop) results from the dual flow paths or passages 14a, 14b resulting from the flat segment front profile 40, and from the multiple apertures or orifices 72, 74, 76, 78, and 79 defined through each respective plate 52, 54, 56, 58, and 60. As depicted, the cartridge 50 may have plates 52, 54, 56 (with corresponding concave and convex surfaces and apertures) in certain exemplary embodiments; in further exemplary embodiments, the cartridge 50 may have a number of additional curved plates (such as curved plates 58, 60), as desired.
While a segmented ball valve 10a has been illustrated as an exemplary embodiment, and any type of rotary control valve 10 may be implement the improvements and features as discussed.
While the exemplary embodiments are described with reference to various implementations and exploitations, it will be understood that these exemplary embodiments are illustrative and that the scope of the inventive subject matter is not limited to them. Many variations, modifications, additions and improvements are possible.
Plural instances may be provided for components, operations or structures described herein as a single instance. In general, structures and functionality presented as separate components in the exemplary configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements may fall within the scope of the inventive subject matter.
Number | Date | Country | |
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63392301 | Jul 2022 | US |