Critical steam conditioning valve technology from Celeros Flow Technology meets the demands of modern steam energy generation

The DSCV-SA (Direct Steam Conditioning Valve – Steam Atomization) from the Copes-Vulcan brand of Celeros Flow Technology is specifically designed to meet the rigours of modern power generation using superheated steam. Already relied on in conventional power generation, refineries, and paper mills, the DSCV-SA is also finding new applications in renewables, including waste-to-energy plants.

Valves for superheated steam control need to deliver operational reliability and withstand extreme operating conditions, particularly during plant start-up, shutdown and turbine trips. The DSCV-SA addresses the issues encountered by older, base load designed bypass valves when employed on modern high frequency, rapid ramp rate plants.

Unlike conventional turbine by-pass valves, the DSCV-SA is designed to use high-pressure balance rather than low-pressure balance. This eliminates risk of wear, damage or breakage relating to piston rings and balancing systems, reducing downtime and maintenance costs. It also avoids stem load fluctuations due to worn seals and surfaces, which can cause lowpressure valves to oscillate violently or not open on command.

The DSCV-SA also features steam atomization technology that has significant benefits over mechanically spraying the cooling water via nozzles. Mechanical spray nozzles rely on the surrounding steam velocity to provide adequate mixing. When the steam load reduces, so too does the steam velocity and the ability of the mechanical spray nozzles. This results in poor downstream steam temperature control and water ‘drop-out’, which can cause high thermal shocks and lead to steam header fracture.

With steam atomization the cooling water is pre-heated; significantly accelerating the evaporation and desuperheating process and producing extremely small water droplet sizes with a vastly increased surface area to promote rapid heat transfer. 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.

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.

Importantly, the DSCV-SA is not a high maintenance valve. It features a ‘Quick-Change’ style trim with no welded-in components or large internal threaded parts. The whole trim assembly is held in compression and simply removing the compression ring or bonnet allows the whole trim to slide out. Therefore in-situ maintenance, if required, is quick and simple with no need for specialised tooling or training.

Robustly designed, 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 individual customer requirements.

The DSCV-SA 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