BVT-PB Process bypass valve

The turbine bypass system consists of both pressure reduction and steam desuperheating. Turbine bypass valves are installed in parallel with the turbine’s pressure stages and provide a secondary conduit for the superheated steam. The valves may be used for controlling the downstream pressure and temperature during turbine operation or during a turbine trip.

Attemperation is the process of controlling the amount of superheat in a boiler or a Heat Recovery Steam Generator (HRSG). Spray water is injected into the superheated steam, reducing its temperature. Spray water flow is controlled by an external water control valve and injected perpendicular to the steam flow using a series of spring-loaded spray water atomizing nozzles. The steam pipe is protected from thermal stresses by a floating liner which also acts as a flow profiler, increasing the relative steam velocity near the nozzles and improving evaporation.
The floating liner is installed without any welding, allowing it to move with the expansion of the material, making it more resistant to cycling.

A steam desuperheater is used for reducing the temperature of superheated to steam close its saturation point, where thermal efficiency is highest. This is performed by injecting spray water into the steam flow. Spray water flow is controlled by an external water control valve and injected perpendicular to the steam flow using a series of spring-loaded spray water atomizing nozzles. The steam pipe is protected from thermal stresses by a welded liner which also acts as a flow profiler, increasing the relative steam velocity near the nozzles and improving evaporation. The number of nozzles are chosen based on the steam pipe diameter, in order to improve the spread of injected water over its cross section, and the nozzle springs are chosen / preloaded to avoid flashing in the nozzle opening.

Feedwater heaters are used in power generation to pre-heat the feedwater coming from the feedwater pump before being fed to the boiler in order to improve steam generator efficiency. The bypass system consists of two 3-way isolation valves, the HB is installed upstream from the heater, and the HBS 
is installed downstream. In normal operation both valves are opened, allowing water to flow through the heater.

Attemperation is used for controlling the degree of superheat in a Heat Recovery Steam Generator (HRSG) or a boiler. Water is injected into the steam pipe using a series of spring loaded atomizing nozzles. Attemperators are installed between the superheater stages in order to protect any secondary superheater pipes from damage owing to excessive heat, called “inter-stage”. Another attemperator is often placed after the boiler / HRSG to regulate the output temperature of the boiler / HRSG or to ensure that the temperature upstream the turbine does not rise too quickly.
The BVT-DLB has a welded flow profiling liner for superior evaporation and performance.

Attemperation is the process of controlling the amount of superheat in a boiler or a Heat Recovery Steam Generator 
(HRSG). Spray water is injected into the superheated steam, reducing its temperature. Spray water flow is controlled by an external water control valve and injected perpendicular to the steam flow using a spring-loaded spray water atomizing nozzle. The steam pipe is protected from thermal stresses by a floating liner which also acts as a flow profiler, increasing the relative steam velocity near the nozzles and improving evaporation.
The floating liner is installed without any welding, allowing it 
to move with the expansion of the material, making it more resistant to cycling.

The BVT-DP2 probe-style desuperheater is a combination of injection nozzle and water control valve, designed for precise and economical control of steam temperature. Water enters through the flanged water connection, and is passed through the desuperheater body installed in the steam pipe at an 45° angle. The nozzle at the end of the desuperheater is equipped with individual feed holes. Water enters the chamber behind the orifice plate through these openings where it is rotated before being injected into the steam flow. This rotational flow as well as the cone shaped mist the nozzle creates at the injection point reduces evaporation time, and thus improves desuperheating.
Water injection is controlled by a diaphragm actuator based on measured downstream temperature.