Case Study I – 210MW Thermal power plant

Problem Statement 

210 MW Coal Fired Thermal Power Station in Maharashtra, was facing frequent erosion of Trim parts of an imported foreign brand, causing leakage in the valve and thus inefficiency.

• Trim parts being imported and being a patented design was expensive and time consuming
• Lower Lifts and High DP results in the wire drawing issues resulting in trim erosion and leakage across the valve
• RH spray application being very critical, any leakages directly affect the efficiency of Turbine resulting in Turbine downtimes
• Spray application is one of the most critical application on the Turbine side of the power plant

Solution provided

Developed a control valve with a trim design to sustain the high pressure drop, by designing a multi-path, multi-stage trim with axial flow and provided grooves in plug for better controllability at lower lifts

Operating Parameters

Inlet Pressure : 158 bar

Outlet pressure: 21 bar

Temperature : 247 Deg C

Fluid: Feed water

CV-3.2

Design Solution:

We offered a Single Control Valve with Axial Flow instead of the Radial Flow as offered in the existing valve.

Axial Flow uses flow to open instead of flow to close in the Radial design. Flow to open valve is safer in case there is a stem shear and separation.

Features:

Axial pressure reducing stages, number of stages varies from 5 to 12,

Solid plug for Class V leakage.

Clamped seat design

The pressure reduction is through axial slots

The gradual increase in stage CV, ensures the trim exit velocity is less than 30 m/s

At low lift, the effective stages are 12 and at full opening the effective stages are 5

This prevents Wire Drawing effects

Hardened Cage of SS 410 provided

Benefit

The end customer benefitted as the control valve with our designed trim is working efficiently, without any shutdown since more than 24 months, saving on the production loss & reduction in costs of imported spares/ trims.

Economics:

Cost was about 40% lower than earlier imported variant