DRAG® control valve for level control applications
IMI CCI is able to offer a one valve solution for drum or boiler level control with the 100DLC DRAG® valve, which meets both the high and low Cv requirements as an alternative to the two valve system. This configuration is only possible due to DRAG® high rangeability trim providing excellent controllability at all flows, from start-up through to normal operation.
Key features
- Multi-stage DRAG® disk stack technology
- Limits trim fluid exit velocity and kinetic energy
- Multi-stage pressure drop
- Multiple ring Teflon packing design
- Customisable flow characterisation
- High integrity spring energised teflon balance seal or graphite seal
- Class V metal seat shut-off with 500 PLI loading force achieves tight shut-off
- Custom designs available for high-temperature and other applications
- Disk stack labyrinth groove design breaks up clearance flow preventing seat ring damage
Benefits
Drum or boiler level control is crucial at plant start-up, when the pressure differential between the Boiler Feed Pump (BFP) and boiler is very high and control is difficult. Boiler Feedwater Control Valves must achieve a smooth start-up and maintain required drum level for safe, reliable and efficient plant operation. The high pressure differential at start-up/low-load, and sensitive control requirement, requires a high-performance severe service control valve
DRAG® reduces costs and improves performance over the alternative two valve solution
The “change over” is eliminated, providing a quick, smooth start-up
Limits fluid velocities, controls vibration and erosion
Reduced plant-trip risk resulting in peace of mind and efficiency improvements regarding maintenance, revenues and fuel
Prevents cavitation damage
Seat replacement and maintenance costs significantly reduced
Eliminates cost of additional second valve and associated system
Stem packing provides low packing friction and long-term leak-free service
Balance seal uses split gland design for easy assembly and long service life
Working with our industry leading valve specialists who have completed our comprehensive Valve Doctor programme
Typical applications
Drum level control of conventional fossil fired plants (combined and start-up)
Start-up feedwater regulator valve on large sub-critical and supercritical boilers
Boiler circulation valves, used on supercritical once-through boilers to maintain minimum flow through the boilers
Product Specification
| Body material ASTM A216-WCB/WCC or A217-WC6
Trim material Disk stack: 400 series heat treated Plug/stem: 400 series heat treated/174PH heat treated Seat ring: 400 series heat treated with hard seat Packing/seals: Glass-filled TFE or graphite Gaskets: Graphite/stainless
Body styles Globe
Velocity controlling stages Up to 20
Sizes 2” to 9” (50mm to 225mm)
Pressure ratings ASME B16.34 1500 to 2500
Guiding Disk stack
Plug design Balanced
Characteristic Equal percentage
Rangeability Designed to meet application needs; minimum of 30:1; over 80:1 possible
Shut-off capabilities ANSI FCI 70-2 class IV, class V
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