DVG/AF Variable Geometry Desuperheater

Instruction Manual D101616X012 DVG/AF Desuperheater DVG/AF Variable Geometry Desuperheater Contents Introduction............................... 1 Scope of Manual.......................... 1 Description............................... 1 Principle of Operation....................... 2 Installation................................ 3 Maintenance Instructions.................... 4 Servicing................................ 4 Disassembly............................. 5 Assembly................................ 6 Troubleshooting........................... 6 DVG/AF Parts Ordering..................... 7 Parts List................................. 7 Introduction Scope of Manual This instruction manual includes installation, maintenance, and operation information for the DVG/AF variable orifice desuperheater. Refer to separate instruction manuals for information on the actuator and accessories. Do not install, operate, or maintain a DVG/AF desuperheater without first being fully trained and qualified in desuperheater, valve, actuator, and accessory installation, operation, and maintenance, and carefully reading and understanding the contents of this manual. If you have any questions about these instructions, contact your Emerson Process Management sales office before proceeding. Description The DVG/AF variable orifice desuperheater (figure 1) provides a convenient and efficient method of reducing superheated steam, and some other vapors, to desired temperature levels. The variable W6981/IL Figure 1. DVG/AF Variable Geometry Desuperheater with Pneumatic Actuator orifice design allows precise temperature control under widely fluctuating process conditions. The DVG/AF features: 1. Fine atomization over a wide range of operating conditions helping to assure rapid and complete vaporization of injected water. 2. No pipe liners, atomizing steam, or separate spraywater control valves are required. 3. Temperature control to within 6-8 C (10-15 F) of saturation. 4. Simple in line installation is accomplished through a standard flange connection. Installation can be in a vertical-up or horizontal pipe. 5. High turndown capability. www.fisher.com

DVG/AF Desuperheater Instruction Manual Table 1. Specifications Steam Line Sizes NPS 8 to 60 Steam Line Connection Sizes NPS 3, 4, and 6 CL150, CL300, CL600, CL900, and CL1500 raised-face flange (consult factory for higher ratings) (1) Spraywater Connection Sizes NPS 1, 1-1/2, and 2 CL150, CL300, CL600, CL900, and CL1500 raised-face flange (consult factory for higher ratings) (1) Maximum Inlet Pressures (2) Consistent with applicable CL150, 300, 600, 900, and 1500 (consult factory for higher ratings) pressure-temperature ratings per ASME B16.34 Inherent Rangeability (3) Up to 25:1 Spraywater Pressure Required 3.5 to 35 bar (50 to 500 psig) greater than steam line pressure Minimum Steam Velocity (4) 9.1 meters per second (30 feet per second) Yoke Boss Sizes and Valve Stem Diameters 71mm (2-13/16 inch) yoke boss diameter with 12.7mm (1/2 inch) stem diameter Valve Travel (Standard) 38mm (1.5 inch) 1. Alternate pressure classes may be available. Consult factory. 2. Do not exceed the pressure or temperature limits in this instruction manual, nor any applicable code or standard limitations. 3. Ratio of maximum to minimum controllable C v, dependent on available water pressure differential. 4. Minimum steam velocity is a function of several application parameters and may be adjusted upward or downward from this standard. Principle of Operation The DVG/AF desuperheater reduces steam temperatures by introducing cooling water directly into the hot steam. Heat transfer accomplishes the desired temperature reduction. The cooling water absorbs heat by conduction and forced convection until the water absorbs sufficient heat for vaporization. By regulation of the water quantity, the degree of heat absorption can be controlled and a specified final steam temperature maintained. The linear positioning of the plug regulates water flow to the sprayhead of the DVG/AF. The main body diameter controls the flow of water, via radially drilled orifices, in the guide cage. A cross sectional drawing of the DVG/AF appears in figure 2. The DVG/AF desuperheater utilizes the proven, spring-loaded AF (Anti-Flash) nozzle to provide a uniform hollow cone spray pattern over a wide range of flow conditions (see figure 3). The water is injected through holes drilled at a compound angle to induce spin as the AF nozzle plug is opened with increasing water pressure. The design of the AF nozzle is such that water flows only after sufficient W6982-1 / IL Figure 2. Detail of DVG/AF Desuperheater backpressure is available to provide a good spray pattern. The full opening of the AF nozzle is limited by a travel stop to keep the spring within its proper working range and to maintain the water film thickness at the necessary thickness for proper atomization. 2

Instruction Manual DVG/AF Desuperheater Table 2. T" Dimensions D T (1) Nominal Pipe Size, Inches NPS BODY STEM SPRING 8 10 12 14 16 18 20 22 24 >24 9.75 8.5 11 10.5 9.5 8.5 10.5 9.5 8.5 8.5 mm 248 216 279 267 241 216 267 241 216 216 PLUG NUT PIN WATER INJECTION HOLES 1. For the NPS 6 mounting flange, add 70 mm (2.75 inches) to the T" dimension. A7191 / IL Installation Figure 3. AF Nozzle Cross Section Always wear protective gloves, clothing, and eyewear when performing any installation operations to avoid personal injury. Personal injury or equipment damage caused by sudden release of pressure may result if the desuperheater is installed where service conditions could exceed the limits of the pressure class noted on the nameplate. To avoid such injury or damage, provide a relief valve for over pressure protection as required by government or accepted industry codes and good engineering practices. Check with your process or safety engineer for any additional measures that must be taken to protect against process media. If installing into an existing application, also refer to the at the beginning of the Maintenance section in this instruction manual. When ordered, the desuperheater configuration and construction materials were selected to meet particular pressure, temperature, pressure drop, and fluid conditions. Do not apply any other conditions to the desuperheater without first contacting your Emerson Process Management sales office. 1. Insert the DVG/AF desuperheater into the flanged pipe stud on the steam pipe (see table 2 and figure 4 for the proper T" length dimension). Bolt the unit to the pipe stud flange in accordance with standard piping practice. 2. Clean and flush out the cooling water line before connecting to the desuperheater. Use only clean sources of cooling water. Use of clean water decreases wear to the valve trim and prevents clogging of desuperheater orifices by solid particles. CAUTION Use only clean sources of cooling water. Emerson Process Management recommends installation of a strainer and isolating valve on the waterline leading to the desuperheater. Failure to use clean sources of cooling water and failure to install a strainer and isolating valve on the waterline may result in clogging of the desuperheater by solid particles, thus hampering temperature control of the steam. 3. A straight run of pipe is required downstream of the desuperheater to ensure complete vaporization of cooling water. Consult the desuperheater certified drawing for the required distance of straight pipe. 3

DVG/AF Desuperheater Instruction Manual 4. Typically, a temperature sensor should be mounted at a minimum distance of 9.1 meters (30 feet) downstream of the desuperheater. This distance will vary depending on steam velocity and percentage of spraywater. Consult the installation drawing provided with the unit for this distance or call your Emerson Process Management sales office. 5. The steam line should have no branch lines between the desuperheater and the downstream temperature sensor. 6. A typical control loop is illustrated in figure 5. A temperature sensor (TE) measures changes in temperature and transmits a signal to a remote temperature-indicating controller or distributed control system (DCS). The output signal from the controller is sent to the positioner on the desuperheater. The positioner output signal is piped to the actuator, which strokes the stem/plug of the desuperheater. A rising stem opens the desuperheater to allow additional water flow. Personal injury could result from packing leakage. Valve packing was tightened prior to shipment; however it should be checked for possible loosening due to shipping and handling. Check with your process or safety engineer for any additional measures that must be taken to protect against process media. Maintenance Instructions Servicing Avoid personal injury or property damage from sudden release of process pressure or bursting of parts. Before performing any maintenance operations: НAlways wear protective gloves, clothing, and eyewear when performing any maintenance operations to avoid personal injury. WATER FLANGE A7192 / IL Figure 4. DVG/AF T" Location MOUNTING FLANGE T HEIGHT NOMINAL PIPE SIZE НDisconnect any operating lines providing air pressure, electric power or a control signal to the actuator. Be sure the actuator cannot suddenly open or close the valve. НUse bypass valves or completely shut off the process to isolate the valve from process pressure. Relieve process pressure on both sides of the valve. Drain the process media from both sides of the valve. НVent the power actuator loading pressure and relieve any actuator spring precompression. НUse lock-out procedures to be sure that the above measures stay in effect while you work on the equipment. НThe valve packing box may contain process fluids that are pressurized, even when the valve has been removed from the pipeline. Process fluids may spray out under pressure when removing the packing hardware or packing rings, or when loosening the packing box pipe plug. НCheck with your process or safety engineer for any additional measures that must be taken to protect against process media. Shut off water and steam flow and vent all system pressure before removal of the desuperheater from the steam line. Disconnect the desuperheater from 4

Instruction Manual DVG/AF Desuperheater TC SPRAYWATER DVG/AF DESUPERHEATER WITH 667 ACTUATOR TE STEAMFLOW C0817/IL Figure 5. Typical DVG/AF Installation the flanged pipe stud and water flange. Withdraw the unit from the line. Temporarily connect the desuperheater to the air supply and verify proper action. To check for seat leakage, connect a water line to the unit and pressurize to service conditions. Disassembly Residual system pressure may be released during the following steps if the system was improperly isolated or vented. Use extreme care to prevent personal injury while loosening any fasteners in the pressure boundary. 1. Disconnect all field connections to the positioner and actuator. Remove the mounting and water flange bolting and remove the DVG/AF from the steam line. 2. Remove the actuator from the DVG/AF using the actuator manufacturer s removal instructions. Reference figure 6 for assistance in disassembly in the following steps. 3. Slowly loosen the bonnet nuts (key 36) approximately 1/16 inch in a uniform manner. 4. Break the bonnet (key 13) loose from the body (key 01). 5. After ensuring that the system is depressurized remove the bonnet nuts (key 36) and washers (key 35). 6. Remove the bonnet (key 13) from the body (key 01) taking care to avoid damage to the stem (key 17). 7. Remove the plug/stem assembly (keys 8, 17 and 18), cage guide (key 15) and seat (key14) for inspection. 8. Examine the removed parts for unusual wear and replace if necessary. 9. Remove and discard the seat gasket (key 30), bonnet gasket (key 31) and stem packing (key 24). 10. Remove the spray nozzle(s) (key 9) by unscrewing them from the nozzle holder after removing the anti-rotation tab(s). 5

DVG/AF Desuperheater Instruction Manual Stem packing is leaking Problem Stem packing is leaking after tightening stem packing nuts Actuator cannot open desuperheater Actuator cannot open desuperheater Actuator action is sticky" Actuator action is sticky" Actuator action is sticky" Temperature is below setpoint Temperature is below setpoint Temperature is below setpoint Temperature is below setpoint Water in steam line Water in steam line when steam line isolated Water in steam line when steam line isolated Bonnet gasket is leaking 11. Inspect the spray nozzles. The nozzles should be completely closed with no evidence of foreign debris or uneven action when opened and closed. If this is not the case and the nozzle(s) cannot be disassembled for cleaning; the nozzle(s) must be replaced to correct the problem. 12. Flush the desuperheater to remove any debris. Clean all gasket and part mating surfaces. Assembly 1. Reassemble the unit with new gaskets and packing following a reverse sequence of the disassembly. Lubricate all sliding surfaces and the bonnet studs and washers with a quality high temperature lubricant. The nozzle anti-rotation tabs can be replaced with any similar sized SA182-F22 (2-1/4 Cr--1 Mo) material or 9018 weld rod if required. Take care to avoid overheating the nozzle or getting weld spatter on the nozzle opening surface. Table 3. Troubleshooting Guide Tighten stem packing nuts Corrective Action Repack and replace worn parts as needed Check actuator calibration. Check for over-tightening of the packing nuts Check for alignment between actuator and DVG/AF Check positioner calibration Replace plug, cage, stem guide and/or packing follower Check water source availability and pressure Check nozzle(s) for plugging Make sure that steam saturation pressure is not above setpoint Check to ensure full actuator stroke is reached Check for proper orientation of nozzle in steam flow Check temperature control loop reset Check nozzle for fouling/poor spray pattern clean/replace Check temperature sensor location relocate per guidelines. Check for proper orientation of nozzle in steam flow Check that steam traps are functioning properly Check for proper desuperheater actuator installation Replace desuperheater seat and plug assembly Inspect body/bonnet mating surfaces, replace bonnet gasket. Ensure bonnet bolts are properly torqued. 3. Reinstall the packing ring, a new packing set, packing follower, flange and nuts. 4. Mount the actuator. When mounting the actuator it is critical to ensure that the stroke is set to ensure that proper seating load is available. Follow the guidelines set forth by the manufacturer in setting up the actuator. In general, position the plug on the seat, move the actuator to full open position, close the actuator for the length of the DVG/AF stroke and then connect actuator and DVG/AF stems. If more complete information is required, consult the actuator documentation. 5. Tighten the packing nuts as required. Torquing values are shown in table 5. Recheck the stem packing for leakage after the system is returned to service and retighten the packing nuts if required. Troubleshooting 2. Tighten the bonnet bolts in a multi-step uniform cross pattern. It is recommended that the bonnet bolt torquing be carried out in a minimum of four torque levels until the final torque is achieved. Torquing values are shown in table 4. The following guide (table 3) is intended as a basic first line troubleshooting guide. Contact your Emerson Process Management sales office for assistance if you are unable to resolve your field operation problem. 6

Instruction Manual DVG/AF Parts Ordering Each desuperheater assembly is assigned a serial number which can be found on the mounting flange of the desuperheater. Refer to the serial number when contacting your Emerson Process Management sales office for technical assistance. When ordering numbers for each part required, the key numbers on figure 6 can be used to help in part identification. DVG/AF Desuperheater Table 4. Recommended Bonnet Bolt Torque Recommended Bolt Size, Inch Threads per Inch Bolt Torque, Lbf ft (1) 5/8 11 125 3/4 10 200 1. Torques for studs with heavy hex nuts. Use only genuine Fisher replacement parts. Components that are not supplied by Emerson Process Management should not, under any circumstances, be used in any Fisher valve, because they will void your warranty, might adversely affect the performance of the valve, and could cause personal injury and property damage. Note Neither Emerson, Emerson Process Management, nor any of their affiliated entities assumes responsibility for the selection, use and maintenance of any product. Responsibility for the selection, use, and maintenance of any product remains with the purchaser and end-user. Parts List Key НН1 НН2 НН3 НН4 НН5 НН7 НН8* НН9* Description Valve Body Valve Body Pipe Water Flange Water Pipe Valve Body Flange Nozzle Mount Plug Spray Nozzle Key Stem Diameter, Inch 1/2 3/4 Table 5. Recommended Packing Nut Torque Description Pressure Rating Н13 Bonnet Н14* Seat Н15* Cage Guide Н17* Stem Н18* Stem Pin Н23 Gland Ring Н24* Packing Set Н25 Gland Follower Н26 Gland Flange Н27 Gland Stud Н28 Gland Nut Н30* Seat Gasket Н31* Bonnet Gasket Н34 Bonnet Stud Н35 Bonnet Stud Washer Н36 Bonnet Stud Nut Maximum Torque, Lbf ft Minimum Torque, Lbf ft CL150 6 4 CL300 7 5 CL600 10 7 CL900 13 9 CL1500 16 11 CL2500 18 13 CL150 12 8 CL300 15 10 CL600 22 15 CL900 30 20 CL1500 37 25 CL2500 45 30 *Recommended spare parts 7

DVG/AF Desuperheater Instruction Manual B2603 / IL Figure 6. DVG/AF Assembly Fisher is a mark owned by Fisher Controls International LLC, a member of the Emerson Process Management business division of Emerson Electric Co. Emerson Process Management, Emerson, and the Emerson logo are trademarks and service marks of Emerson Electric Co. All other marks are the property of their respective owners. The contents of this publication are presented for informational purposes only, and while every effort has been made to ensure their accuracy, they are not to be construed as warranties or guarantees, express or implied, regarding the products or services described herein or their use or applicability. We reserve the right to modify or improve the designs or specifications of such products at any time without notice. Neither Emerson, Emerson Process Management, nor any of their affiliated entities assumes responsibility for the selection, use and maintenance of any product. Responsibility for the selection, use and maintenance of any product remains with the purchaser and end-user. Emerson Process Management Marshalltown, Iowa 50158 USA Sorocaba, 18087 Brazil Chatham, Kent ME4 4QZ UK Dubai, United Arab Emirates Singapore 128461 Singapore www.fisher.com Fisher 8 Controls International LLC 1990, 2008; All Rights Reserved Printed in USA