vAlve design
increased surface area to promote rapid heat transfer . The atomized , pre-heated water is introduced via a combining tube where it is atomized and then passed through a converging-diverging venturi throat section . The hot atomised water exits the atomising head and is rapidly evaporated , cooling the main steam flow . Because this method of water introduction does not rely on surrounding steam velocity or turbulence for effective mixing , it gives very high turndowns - generally in excess of 100:1 .
Robust design
In terms of design , the DSCV-SA has a standard body-to-bonnet joint , up to ANSI 900 #, which is bolted and incorporates a fully enclosed spiral wound gasket made from 300 stainless steel with graphite filler . For pressure ratings above ANSI 900 #, a pressure seal bonnet closure is employed , which utilizes a graphite sealing ring . The DSCV-SA is available in an almost infinite range of sizes , materials and pressure ratings as each valve is tailored to suit particular customer requests and requirements . The valve can be fully rated or split rated and is available in standard , special or intermediate classes . Standard classes are available up to and including ANSI 4500 # and intermediate and
special class designs can be accommodated where required . As the DSCV-SA is usually supplied as a split rated design , this provides the customer with a convenient point for pipe transition for size , rating and material . The DSCV-SA is of a two-part construction and therefore virtually any configuration can be met to satisfy client requirements . Modern steam turbine bypass systems must be able to react and modulate very quickly under emergency conditions such as a turbine trip . Stroking speeds of less than one second may be required and as a result , the DSCV-SA can be supplied with either pneumatic or hydraulic actuation to meet this critical requirement .
Low maintenance
Importantly , the DSCV-SA is not a high maintenance valve . The complete trim is a ‘ Quick-Change ’ style with no weldedin components or large internal threaded parts . The whole trim assembly is held in compression by either a compression ring or the bonnet . Simply removing the compression ring or bonnet allows the whole trim to slide out the top of the valve . Therefore in-situ maintenance , if required , should be both expeditious and uncomplicated with no need for specialised tooling or training .
Conclusion
Superheated steam continues to play a pivotal role in electricity generation and other essential industries . Climate change and the need to use resources even more efficiently will no doubt bring new flow control challenges in the coming decades . Innovations such as the DSCV- SA will be essential in delivering the high performance and operational efficiencies that are the basis of a more sustainable future .
About the author Mark Wheat is Copes-Vulcan Global Technical Sales Manager for Celeros Flow Technology . He is a qualified engineer with more than 35 years of experience and specializes in steam power distribution and thermodynamics . He joined Copes-Vulcan in 1995 as Export Sales Manager and has held positions of increasing seniority within the company , including Director GM UK Operations . Since 2001 , Mark has applied his considerable expertise on steam turbine bypass applications and other critical valve applications around the boiler island .
PNEUMATIC ROTARY ACTUATOR
Head Office & Factory Address : ����������������������������������������������������������������� ��������������������AHMEDABAD�����������
Contact : ���������������� E Mail : �����������������������������������������
20 Valve World February 2024 www . valve-world . net