PRODUCT SPECIFICATION SHEET – SD2K DESUPERHEATERIntroductionThe spray desuperheater type SD2K is designed toreduce the temperature of vapour by the introduction ofa coolant directly into the hot fluid to achieve contactdesuperheating. The coolant is atomised as it passesunder pressure through a series of spray nozzles,which assists it in evaporating into the vapour andresults in an increased quantity of vapour at thespecified final temperature. The unit is available inthree models: designated models 3/2, 3/3, 3/5. Models3/2, 3/3 and 3/5 are provided with a 3” body andmounting flange and have 2”, 3”, 5” of travel,respectively.Product DescriptionThe desuperheater is available in pressure class’s300lb, 600lb, 900lb, 1500lb, and 2500lb per ANSIB16.5. The head is designed using the rules of ANSIB16.34 and is supplied for mounting to a suitablebranch on the main vapour header.All units employ the option for 1”, 1.5” and 2” coolant connections, which are flanged as standard tothe ANSI rating equivalent to the head rating.The Desuperheater head incorporates a bolted compression type-packing gland, which utilisesgrafoil packing in order to seal the stem and the head is provided with a 2.75” diameter screwedmounting boss to accept a CV 700 spring opposed diaphragm actuator.Suspended below the head is the desuperheater cage, which incorporates the multiple spraynozzles and houses the desuperheater plug and stem assembly. This cage is attached to the headby a cage-retaining ring which method of attachment enables the nozzle arrangement to bedispositioned in any position relative to the coolant inlet branch. The lower end of the cage is sealedwith a plug, which incorporates the seat for shutting off the flow of coolant to the spray nozzleswhen the plug is in the highest position.The spray nozzles are screwed into the cage and then tack welded into position. Model 3/2 unit isprovided with 10 nozzles, the model 3/3 is provided with 14 nozzles, the model 3/5 is provided with22 nozzles. These nozzles are of a proprietary design, which incorporate a swirl plate, which is fedby a discharge port designed to achieve the optimum velocity through each individual nozzle.The operating plug, which is connected by the stem to the valve actuator, is fitted with piston ringsto optimise turn down and improve nozzle definition.REVISION No: 02 SHEET 1 OF 4
PRODUCT SPECIFICATION SHEET – SD2K DESUPERHEATERPrinciple of OperationThe coolant fluid enters the desuperheater head through thecoolant branch and passes into the cage where with the plugon its seat no fluid is admitted to the spray nozzles. The initialmovement of the actuator will move the plug off its seatallowing fluid to pass through. Subsequent movement of theactuator will move the plug to uncover successive rows ofspray nozzles and in this manner the quantity of fluid into thevapour flow is controlled. As fluid enters the discharge portbehind each spray nozzle, a high velocity flow is set-upinduced by the pressure drop between the coolant pressureand the vapour pressure. This high velocity flow jet enters theswirl chamber at the rear of the spray nozzle and assumes aswirling action, which results in a fine spray cone dischargingthrough the individual nozzles.Materials of ConstructionBody (Cast):Cage Retaining Ring:Cage (Upper):Cage (Lower):Plug:Stem:Spirol Pin:ASTM A217, Grade WC6ASTM A217, Grade WC9ASTM A351, Grade CF8MASTM A182, Grade F11 orASTM A182, Grade F22ASTM A182, Grade F11 orASTM A182, Grade F22ASTM A743, Grade CA15ASTM A276, Type 420, HardenedASTM A276, Type 316, Condition BType 316 SSPiston Ring: Type JP 900Swirl Disc:Orifice Disc:Gasket:Stainless SteelASTM A276, Type 420, HardenedSpiral wound 304 SS with Graphite FillerREVISION No: 02 SHEET 2 OF 4
PRODUCT SPECIFICATION SHEET – SD2K DESUPERHEATERMinimum Pipe SizeThe Minimum header or liner inside diameter for the Model 3/2 is 4.50 InchesThe Minimum header or liner inside diameter for the Model 3/3 is 5.50 InchesThe Minimum header or liner inside diameter for the Model 3/5 is 7.50 InchesCoolant PressureCoolant pressure should be a minimum of 30 psi (2 bar) and a maximum of 2000 psi (138 bar)above the vapour pressure. The maximum static pressure for the coolant should not exceed 2000psig (138 barg) or the pressure rating of the unit head.Temperature LimitationsA Maximum temperature of 1050 o F (565 0 C)applies to alloy steel units.Velocity LimitsFor successful desuperheating a minimum velocity is required in the vapour header. In order toensure that the unit is not noisy in service or does not give rise to erosion problems, a maximumvelocity is also stipulated, The upper and lower limits of velocity are as follows: -Maximum Vapour Velocity = 50,000 ft/min (254 m/s)Minimum Vapour Velocity = 1,500 ft/min (7.5 m/s)Maximum Vapour Velocity = 30,000 ft/min (150 m/s) to limit pipeline noiseTemperature Control AccuracyThe temperature Control accuracy with this type of desuperheater is +/- 9 o F (5 0 C)Minimum Controllable TemperatureBecause of the above temperature control tolerance the unit can control temperature down to aslow as 15°F (8 0 C)above saturation pointTemperature Sensing Point LocationThe location of the temperature sensing point downstream of the SD2K is governed by theThermodynamic Conditions and varies from 16 ft (5 m)with the smallest Cv, up to 30 ft (9 m) withthe largest Cv.
PRODUCT SPECIFICATION SHEET – SD2K DESUPERHEATERREVISION No: 02 SHEET 3 OF 4OrientationThe unit can be installed in either horizontal or Vertical pipe run.If the unit is installed in a vertical pipe run, the actuator must be installed horizontally and flow mustalways be in an upward direction. It is recommended that when this configuration is used, a drainpot is placed at the bottom of the vertical run.All units must be installed such that the discharge nozzles face directly downstream.In locating the SD2K in the vapour line it is recommended that the upstream pipe should be straightand of uniform diameter with no expanders, tees, elbow or control valves within 5 pipe diameterswith a minimum of not less than 4 ft (1.2 m). This is to ensure that flow disturbances do not impactupon the performance of the desuperheater. It is recommended that there be straight pipe from theSD2K to the temperature sensor.02 REVISED TO CV700 ACTUATOR PM BRH 02/09/0401 ADDED TACK WELDING NOTE TO NOZZLES IJW BRH 08/02/0000 ORIGINAL ISSUE IJW BRH 08/07/98REV DESCRIPTION MADE BY CHECKED DATEREVISION No: 02 SHEET 4 OF 4