Introduction

Turbine bypass valves play a very major role in Power Plant applications. Within a short period of twenty four hours, a power plant may be required to operate at minimum load, increase to maximum capacity for major part of the day, immediately lower back to minimum load and then back to maximum capacity. Bypass System permit unit start up and shutdown in a lifesaving manner for critical heavy components in boiler and turbines. Bypass valves are supplied with hydraulic, electric or pneumatic actuators as per the process requirements along with complete control systems as an option.

Functions

• To perform quick and economic start up, including cold start, warm start and hot start in a lifesaving manner for critical heavy components in boiler and turbine.
• To operate with the boiler shutdown.
• To perform warm and hot startup in a short time after a trip i.e. brings the unit back to load
• To run the unit down to house load.
• To perform real “two-shift’ operation”.
• To avoid condensate losses to the atmosphere and reduce the start up noise to the ambient outside the plant.

Applications:

There are two different applications: 1) Bypass Systems which are occasionally in operation. Among these there are startup and shutdown conditions and emergency conditions, for example after turbine trip. 2) Bypass System which are often or permanently in operation, for example for process steam or heating application.

Actuators:

Bypass valves can be supplied with Pneumatic Piston & Cylinder, Electric or Hydraulic Actuators alongwith power pack and complete control system as per the requirements of the system.

Materials:

For most sizes, casting or forgings in Carbon and Alloy Steel can be supplied. For extremely large sizes, units are fabricated. Bypass Valves are normally supplied with butt weld ends. However, if required can be supplied with flanged ends. Multi – Stage Multi – Path Pressure Reduction trim Stage Technology: 1) The only reliable and proven long term solution for eliminating of noise, cavitation, flashing, vibration and erosion is to control velocity of fluid. Our Multi–stage Multi-Path disc stack trim technology for successful operation of our valves in severe service conditions. 2) The fluid passes through am extremely tortuous path at right angle turns thereby reducing the fluid velocity and therefore reduces the noise and eliminates erosion and vibration problems. This trim design is tailor – made as per the requirements of customers.