CCI Sweden (formerly BTG Valves) has further modified its VLB steam-conditioning valve for use in high- and/or low-pressure systems in the process industry. This design allows for continued start-up and shutdown of different loops in the power plant with a minimum of heat losses. It keeps the steam in balance with load requirements, and handles abnormal conditions such as load rejection, turbine, pump or fan trips etc. that allows for the system to return to normal operation with minimum delay. The VLB valve is a pressure-reducing valve with an integrated cooling system with a steam flow throttled through a cage type plug with multiple drilled holes. This provides optimum characteristics for control of the steam pressure. The pressure reduction continues in the outlet that is furnished with pressure reducing pipes. The spray water is injected through spring-loaded variable nozzles after final pressure reduction of the steam, providing an excellent spray pattern during the whole load range. This means no erosion problems with valve internals. For combined cycle applications, the standard VLB valve is available with a balanced tight cage plug-design, with leakage less than Class V and a pilot plug reducing actuating force that allows pneumatic actuation. The tight cage plug design is standard for hydraulic operated bypass valves used in conventional drum boiler applications. Both designs contain a drilled control cage which moves inside the prolonged valve bonnet. The bonnet has also a drilled part which results in two variable pressure reduction stages before the steam is expanded through the valve seat. This further reduces the risk for noise and vibration problems from the valve. The VLB has been proven successful in installations for 25 years.
