With its Copes-Vulcan brand, Celeros Flow Technology has been providing control valves and desuperheaters for the power, process and nuclear industries since 1903. Copes-Vulcan provides a wide range of valves for the control of pressure, temperature and flow-induced noise in all types of power plants. Products include severe service and general service control valves, variable orifice desuperheaters, Raven™, trim and steamconditioning valves and nuclear control valves, as well as custom designed specialty valves. The Copes-Vulcan brand is recognized worldwide as a leader in valves for severe and critical service applications. Our strength lies in our ability to provide innovative valve solutions for our customers’ application needs.
VARIABLE ORIFICE DESUPERHEATER
Copes-Vulcan’s VO Variable Orifice Desuperheater is recognized industry wide as the most versatile desuperheater available. It is easily capable of meeting the most demanding needs for desuperheating in both the power and process industries. The VO offers extremely fine control and exceptional turndown that is limited only by the rangeability of the coolant control valve itself. With excellent mixing of vapor and coolant, control is possible throughout the entire operating range to within ± 5° F (± 2.5° C) of the set point which can be as close as 10° F (5° C) above saturation. The coolant pressure which is required at the inlet to the VO need only be 5 psi (35 kPa) above the pressure of the vapor being desuperheated. Because virtually all of the desuperheating occurs within the VO body itself, the temperature sensing element can be as close as 14—20’ (4—6m) from the desuperheater outlet.
DESCRIPTION AND PRINCIPLE OF OPERATION
The Variable Orifice Desuperheater consists of a body which houses the desuperheater internals. The body incorporates a screwed-in seat over which a cage is located in such a manner that a coolant annulus is created around the seat. The coolant enters this annulus by means of a branch on the desuperheater body. The plug is free floating but incorporates a spring-loaded button which provides stability to the plug under light load conditions. Incorporated in the top of the cage is a plug stop to limit the amount of travel of the plug. As more vapor flows through the desuperheater, the higher the plug is lifted, thus creating a variable orifice for the vapor flow. The energy used in lifting the plug creates a pressure drop across the seat which is quite constant regardless of the vapor flow. This pressure drop creates a relatively high velocity across the seat area, and it is at this point of low pressure constant velocity that the coolant is admitted into the vapor flow. Coolant enters the annulus under the dictates of a control valve responsive to a temperature controller sensing the downstream vapor temperature. The coolant is admitted into the vapor flow through a peripheral gap between the underside of the cage and the top of the seat. Coolant is admitted all around the seat, thus ensuring that unequal cooling does not occur. The coolant is picked up by the vapor flow as it discharges from the seat, and the low pressure zone that exists at this point is instrumental in atomizing the coolant into fine particles. In the turbulence which ensues as a result of the change in direction and velocity of the vapor, intimate mixing of the vapor and coolant takes place. Above the plug, as the vapor attempts to return to laminar flow, a vortex is created and any particles of coolant not completely absorbed by the vapor are drawn into this vortex where they suffer a further pressure reduction which again speeds up the atomizing process. As virtually all of the desuperheating occurs within the desuperheater body itself, and as no coolant impinges on either the desuperheater or associated piping, no protective thermal liners are required.
INSTALLATION
The desuperheater is designed for installation in a vertical run of pipe with flow upwards. In most cases, there are no requirements for straight pipe upstream or downstream of the unit, however, if a bend is located immediately at the outlet, it should be a long radius elbow.
For more information you can email our Sales Manager directly at frikkie@kvcontrols.co.za
KV Controls was founded in 2016 situated in Sasolburg, we supply Total Cost of Ownership and optimum valve solutions to major industries such as chemical, refining, mining & minerals, pulp and paper, sugar and power generation industries throughout Southern Africa & Africa
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