Flowserve Launches The Urea Letdown Valve
Urea is a common chemical reactant and precursor used in the production of other chemicals and materials, including fertilizers, resins, plastics, and paper. Produced at high temperatures and pressures, it is both highly corrosive and erosive. The urea letdown process happens near the end of the production cycle, where the pressure is reduced to a more easily handled state.
"Urea production and letdown is a critical component of many chemical processing operations," says Brent Stewart, chemical product specialist, Flowserve Flow Control. "Flowserve has designed the Urea Letdown Valve specifically to handle the tough requirements that urea letdown places on a control valve."
Typical urea production conditions include an inlet pressure of 3,500 psig, an outlet pressure of 300 psig, an operating temperature of 350°F, and a flow rate of 8 million SCFH. A valve typically used in this process would be a 4" ANSI Class 2500.
To combat the challenge of high pressure drops during letdown, the Flowserve Urea Letdown Valve features a robust and rugged design with double top-stem guiding, single-point throttling, a single-piece plug, and a clean and streamlined exit. This design minimizes the vibration, noise, sticking and plugging common to valves not specifically designed to work in urea letdown.
Constructed of Urea grade 316 stainless steels, the Flowserve Urea Letdown Valve features a specially shaped venturi seat ring, sweep angle design, advanced velocity control, straight-shot exit, and a large, oversized gallery. These elements help mitigate the erosive effects of the continuous, high-velocity flow of urea, which can also contain entrained particulates.
Additional features of the Flowserve Urea Letdown Valve include an extra thick valve stem for added durability, top-entry design for easy maintenance, special plug contours for varying flow characteristics, and the availability of ring joint connections. While custom-designed, the Flowserve Urea Letdown Valve is readily available in 1" to 4" sizes.
As protection against urea crystals destroying the valve packing, the Flowserve Urea Letdown Valve also employs an advanced and proprietary crystal-resistant wiper ring packing. The specialized packing design includes an added lubricator and wiper guides. These features keep urea crystals from entering the valve bonnet and damaging the packing.
The Flowserve Urea Letdown Valve comes standard with the Flowserve VL cylinder actuator, a piston actuator that provides the thrust and stiffness required to handle the high pressures of the urea letdown process. The valve is compatible with virtually any four-way digital or analog positioner.