prds manual yoprds rev1

8/22/2019 Prds Manual Yoprds Rev1

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Pressure Reducing / De-superheating Stations(Control Valve based)

Instruction Manual


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Notice

2006 SteamlineSurvey. No. 32/3/14

Behind Angraj Resort,Kondhwa BudrukPune 411 048 INDIAPh: 91 20 2693 2213Fax: 91 20 2693 2214E-Mail: [email protected]: www.steamline.comAll Rights ReservedPrinted in India

Proprietary Material

The information and descriptions contained herein are the property ofSteamline. Such information or descriptions may not be copied orreproduced by any means, or disseminated or distributed without theexpress prior written permission of Steamline, Survey. No. 32/3/14, BehindAngraj Resort, Kondhwa Budruk, Pune 411048, India.

This document is for information only and is subject to change withoutnotice.

Statement of Limited Warranty

Steamline warrants equipment of its manufacture, and bearing itsidentification to be free from defects in workmanship and material for aperiod of 18 months from the date of delivery, or 12 months from the date ofinstallation, whichever is earlier, when such equipment is used inaccordance with instructions furnished by Steamline and for the purposesdisclosed in writing at the time of purchase, if any. Steamlines liability underthis warranty shall be limited to replacement or repair, F.O.B. Pune, India, ofany defective equipment or part, which having been returned to Steamline,transportation charges prepaid, has been inspected and determined by

Steamline to be defective. Replaceable elastomeric parts and glasscomponents are expendable and are not covered by any warranty.

This warranty is in lieu of any other warranty, either express or implied, asto description, quality, merchantability, fitness for any particular purpose oruse, or any other matter.

Part No. YOPRDS Rev 1

May 2007

PRS/ DSH/ PRDSH (CV based) Page 2 of 16


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Table of Contents

1.0 INTRODUCTION Page 41.1 Application1.2 Operating Principle1.3 List of Documents Attached

2.0 SPECIFICATIONS Page 82.1 Operating Conditions2.2 Applicable Standards2.3 Mechanical Specifications2.4 Materials

3.0 INSTALLATION Page 9

3.1 Unpacking the unit3.2 Mechanical installation3.3 Commissioning3.4 Insulation

4.0 OPERATION Page 10

5.0 MAINTENANCE Page 115.1 Steam Trap5.2 Strainers5.3 Other Parts5.4 Annual Maintenance

5.5 Calibration

6.0 TROUBLESHOOTING Page 126.1 Outlet Pressure is not correct6.2 Safety Valve does not operate

7.0 SERVICE & SPARES Page 137.1 Service Policy7.2 Warranty Repairs7.3 Spares Parts7.4 Service Record

8.0 NOTES Page 16



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1.0 INTRODUCTION

1.1 Application

Pressure Reducing Stations are integral parts of any steam system. They are usedto reduce the pressure (and correspondingly, the temperature) of steam. Steam isusually generated at high pressures at a central location (the boiler house) andtransferred to usage points through the steam system. At the various points ofsteam usage, pressure is dropped according to the requirement of each process.

Why cant steam be generated at low pressure?

Most modern boilers operate at relatively high pressure. A typical process boileroperates at 10.5 to 17.5 kg/cm2g (150 250 psig). The operating pressure of aboiler determines various parameters like water holding capacity, steam space,

water level etc. Such an arrangement has the added advantage that smallerdiameter distribution pipes can be used, as the specific volume of steam occupiedby steam is less at higher pressures. So it is usual practice to generate steam athigh pressures at a central location, distribute the high pressure steam in smalldiameter pipes, and reduce the steam pressure as required at the usage points.The temperature of saturated steam varies with the pressure, so this also providesa simple method of controlling temperature of steam going to a process.

Economic benefits of Pressure Reduction

If steam at a higher pressure (and temperature) than required is used in a process,the heat will be sufficient for the process. So why reduce steam pressure? There is

a powerful economic argument in favour of reducing the pressure: latent heat. Thework done by steam in a process is primarily latent heat, which is far greater thensensible heat i.e. steam imparts heat to the process by condensing into water, thusgiving off its latent heat. Latent heat is higher at lower steam pressures, so thesame amount of heat load can be catered by a smaller quantity of steam at a lowerpressure. The minimum pressure to be used has to be chosen such the steamtemperature at that pressure affords enough of a temperature gradient for efficientheat transfer to take place. Sometimes, steam-using equipment will have to beoperated at the steam pressure specified by the manufacturer of the equipment.

Superheating

Superheated steam is steam that is at higher temperature compared to itssaturation temperature for the given pressure. Eg, steam at 3.5 bar g has asaturation temperature of 147.71C. If further heat is added to steam at the samepressure, the extra heat raises the temperature of steam to become superheated. Itis higher than saturation temperature and contains more energy.

Superheated steam is mainly used to drive turbines for power plants. Here we needsteam which has a high dryness fraction, so that the turbine's expensive blades arenot subjected to pitting by water droplets carried by wet steam.

De- superheating

Once utilised for any special purpose, superheated steam must be cooled down tosaturation temperatures for efficient use on heating applications. This process is



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called desuperheating. Most desuperheaters used to restore the saturated stateproduce discharge temperatures approaching saturation.

1.2 Operating Principle

a) PRS: The figure below shows the general arrangement of a typical PressureReducing Station (PRS). The Moisture Separator at the inlet ensures that any waterslugs (condensate) traveling with the steam does not cause damage to the rest ofthe PRS, and provides dry steam to the process. The inlet valve can be used toshut-off steam supply to the PRS. The strainer removes dirt, welding slag or anyother particles that could damage the seat and plug of the CV. (Please refer to theenclosed User Manuals of CV.)

Pressure at the outlet is read by a Pressure Transmitter, to act as a feedback tobalance pressure to the set pressure.

The outlet valve shuts off supply to the process, while the bypass line and valveprovide an alternative flow path in case the CV needs to be repaired ormaintenance work is required. A suitably sized safety valve ensures that the outletsteam pressure does not exceed the set-point. Inlet and outlet pressure gauges areprovided to check generation pressure, configure the set pressure and check CVoperation.

b) DSH: A measured amount of water is sprayed into the superheated steam via amixing arrangement within the desuperheater (DSH). As it enters the DSH, thecooling water evaporates by absorbing heat from the superheated steam.Consequently, the temperature of the steam is reduced. The amount of wateradded is controlled precisely by using a sophisticated feedback control loop.



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Determining the amount of water to be added is usually achieved by measuring thetemperature of the steam downstream of the desuperheater.

The system below illustrates an arrangement of a typical DSH. Good quality water(typically condensate or boiler feedwater) is directed into the superheated steamflow, removing heat from the steam, causing a drop in the steam temperature tosaturated temperature levels for given pressure.

Water

Str

c) PRDSH: This stands for Pressure Reducing and De-Superheating Station. It

combines the Pressure Reducing Stage and the De-Superheating stage as shownin the diagram below.

Water



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1.3 Documents Attached

Packing List (with dispatch documents) Copy of Re-Assembly Drawing of PRS / DSH / PRDSH (with dispatch

documents)

Copy of As Built Drawing of PRS / DSH / PRDSH

User Manual of Control Valves, Type 241-1 or Type 3251

User Manual of Control Valve Positioner

User Manual of Pressure Transmitter (if applicable)

User Manual of PID Controller (if applicable)

User Manuals of Safety Valve

IBR Drawing of PRS / DSH / PRDSH (where applicable)

IBR Form IIIA with material traceability (only for IBR PRS / PRDSH)

Material Traceability Certificate Copies of Certificates of all materials used



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2.0 SPECIFICATIONS

2.1 Operating ConditionsSteamline Pressure Reducing and De-superheating Stations are custom built to

operate over a wide variety of operating conditions. To determine the OperatingConditions for the supplied PRS / PRDSH, please refer to the enclosed drawings asper section 1.3 above.

2.2 Applicable Standards

All SteamlinePressure Reducing and De-superheating Stations are manufactured

in conformance to one or more of the following applicable standards:

Quality Procedure (IBR Job) : Indian Boiler Regulations 1950 or later

Quality Procedure (NIBR Job) : SQC/QAP/PRSN 2000 or later Pressure & Temp Ratings : ANSI 150# or 300# or 600#Sizing of Control Valves : IEC 534Seat Leakage Tests : ANSI B 16.104Sizing of Safety Valves : IBR sizing formulaDesign of Safety Valves : API 526 + ASME Sec VIIITesting of Safety Valves : API 527 + IBRCast Carbon Steel Valves : ASTM A 216 Gr. WCCMfg of Cast CS Valves : API 600 / BS 1873Mfg of Forged CS Valves : API 602Face to face dim of valves : ANSI B 16.10SW or threaded Pipe Fittings : ANSI B 16.11

Inspection of all CS Valves : API 598Design of Pressure Gauges : EN837 1Piping Standards : ANSI B31.1 & 31.3Carbon Steel Pipes : ASTM A 106Sizing of Steam Pipes : SQC SoftwareSteel Pipe Flanges : ANSI B 16.5Forged Carbon Steel Pipe Fittings : ASTM A 182Gaskets for steel piping : IS: 2712: 1979Heat Resistant Paint : IS: 13183: 1991Fasteners : ASTM A 193/4 or IS 1367

2.3 Mechanical Specifications

Mounting : Outdoor (non-corrosive environment)Protection Rating : IP65 (Except Electronic Controllers, if any)Ambient Temperature : 0 to 50 degrees COther Specifications : As per enclosed drawing

2.4 MaterialsCV & Safety Valve Body : ASTM A216 Gr WCCCV & Safety Valve Internals : Stainless SteelIsolating Valves Body : ASTM A216 Gr WCB / ASTM A105Separator & Strainer Body : ASTM A106 Gr BPressure Gauges : Stainless Steel case + internalsSteam Trap (where fitted) : Thermodynamic, SS

Steel Pipes : ASTM A106 Gr BGaskets : CAF

Nameplates : Metal-photo Aluminium



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3.0 INSTALLATION

3.1 Unpacking

The unit is usually supplied in disassembled condition for ease of transport. If theunit is packed in a wooden case, pry open the case carefully. Great care is taken toensure that no damage occurs in transit. However, please notify the carrierimmediately if there are any signs of damage to the unit. Refer to the enclosedPacking List to check if any parts are missing. The case should contain the variousparts, with each part bearing a re-assembly number, usually hand-written with amarker. Refer to the Re-Assembly drawing to assemble the syste at site.

3.2 Mechanical Installation

1. Before starting the installation, ensure that a full set of tools is available,

including a full set of spanners. The installation personnel should be equipped withsafety belts and helmets. Ensure that there is no possibility of steam being chargedto the line where the system is being installed.

2. In case of IBR approved unit, the local IBR inspector may have to be notifiedbefore installation. The IBR certificate in Form IIIA (out of Maharashtra) or in letterform (within Maharashtra) needs to be shown to the local IBR inspector. All localinspection formalities by IBR are in the scope of the client.

3. Assemble the system in the pipeline as per the As-Built Drawing provided.Ensure that the valves and other components are installed with the flow in thecorrect direction, as shown on the part. If in doubt, contact Steamline. Install the

isolating valves in a manner to allow convenient operation of their hand wheels.Install Pressure Gauges so that they can be seen from the normal viewing position.

4. If the system is installed at a height, fabricate a suitable platform to allow accessto the unit for operation and maintenance. Provide supports before and after theCVs do not support the weight of the system on any working component like CV,valves etc. as this could cause damage to these parts over time.

5. Keep the inlet isolating valve and the bypass valve fully closed, and the outletisolating valve fully open for now. Keep the bypass valve of the trap open for now.

3.3 Commissioning

After the installation is completed, check that there is no water leak from theCondensing Pot. Slowly open the main line valve (at boiler header) to charge steamto the PRS/PRDSH. Any stored condensate in the line will now discharge throughthe trap bypass valve. Close the bypass valve of the trap, and fully open its inletvalve. The trap should then resume its normal blast discharge to remove thecondensate.

Check that there are no leaks of steam from flanged joints etc. and that the inletpressure gauge reflects the correct inlet pressure.

Now slowly open the bypass valve. As the outlet pressure rises, the gauge should

reflect this. Once the outlet pressure rises to 10% above the set pressure, thesafety valve should lift check that this happens correctly. If required, adjust thesafety valve pressure (Refer to the enclosed manual of the safety valve forinstructions).



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Once the safety valve operation has been confirmed, slowly open the inlet isolatingvalve of the PRS/PRDSH, while closing the bypass valve simultaneously. The outlet

pressure will now be controlled by the PRV. If the outlet pressure is not correct asper the chosen set pressure, adjust the PRV (Refer to the enclosed manual of thepressure reducing valve for instructions).

Now fully open the inlet valve and outlet valve of the PRS/PRDSH and fully closethe bypass valve. These valves are supplied with the gland packing nuts slightlyloose to allow for expansion of the gland packing tighten these nuts fully so nosteam escapes through the gland. The PRS/PRDSH is now commissioned, and willautomatically regulate the pressure as per the set pressure selected.

3.4 Insulation

If desired, the system may be insulated in a similar manner as the insulation of thepipe. Please contact Steamline if you need information and specifications forrecommended insulation materials. Do NOT insulate the CV and the Safety Valve,as this will interfere with their normal operation. While insulating the Strainer, it isadvisable to make a provision for removal of insulation from the top flange, whichmay be required for maintenance.

4.0 OPERATION

PRS / Pressure reducing Stage of PRDSH

The system includes,

(a) an Input the Pressure Transmitter(b) Controller(c) Steam Pressure Control Valve

The steam pressure CV will be modulated by the PID controller to maintain the SetPoint at the outlet of the system.

To operate/ configure the controller, please refer to the controller manual.

Temperature Control Stage of PRDSH / DSH

In the temperature control stage there are three parts,

(a) an RTD the Temperature Transmitter(b) PID Controller(c) Water spray Control Valve

The Controller will modulate the quantity of water sprayed so that it is just enoughto maintain the set temperature.

To operate/ configure this controller, please refer to its controller manual.



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5.0 MAINTENANCE

Steamline Pressure Reducing and De-superheating Stations are designed to give

long periods of uninterrupted service over many years, even with little or nomaintenance. However, a little care taken on the following points will ensure thatthe best results are achieved.

5.1 Steam Trap (in case of PRS)

The steam trap on the motive steam line ensures that there is no moisture in themotive line. The operation of the trap needs to be checked regularly, as water in themotive line could cause water hammer and damage the Control Valve. Werecommend a weekly inspection.

5.2 Strainers

The PRS / PRDSH includes a strainer. As time passes, particulate matter and dirtwill collect in the mesh of the strainer, and the mesh will have to be cleaned. Thiscan be done on line by operating through the bypass, but it is best done duringannual maintenance shut down. Any paraffin can be used to clean the SS mesh.The steam trap also has an in-built strainer, which may require cleaning.

5.3 Other parts

The internals of the unit are factory assembled and tested, and should not betampered with as far as possible. We do not recommend any user servicing ofthese parts, and checks are required annually, which will be conducted by

Steamline personnel if the equipment is under Annual Maintenance Contract.

5.4 Annual Maintenance

While the unit is warranted for a period of one year, Steamline service can beextended to ensure optimal operation of the system by entering into an AnnualMaintenance Contract with Steamline. This will include periodic visits and checks onyour PRS / PRDSH unit and replacement of any worn parts etc. Please contact yourSteamline representative for details.

In case you do not need an AMC, ensure that during the annual maintenanceshutdown, the PRS / PRDSH is inspected. All strainers should be cleaned, the

gaskets may need to be replaced in case of any leakage. Tighten all pipeline nutsand inspect insulation for any damage. Reconfirm operation of the safety valve at10% above set pressure.

5.5 Calibration

The Pressure Gauges and Pressure Transmitter should be calibrated at least oncein two years, or in accordance with Quality Procedures followed in the plant.



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6.0 TROUBLESHOOTING

6.1 Outlet Pressure is not correct

In case of minor deviation from the set point, adjust the controller settings to correctthe pressure. If the system does not hold the set pressure consistently, check thatthe inlet and outlet valves are fully open, and the bypass valve is fully closed. Alsocheck that the bypass valve is not leaking.

Should the downstream pressure deviate significantly from the adjusted setpressure, check the set point and PID settings in the controller. Now, set up thecontroller in auto-tuning mode. In case the problem persists, please contactSteamline service.

6.2 Safety Valve does not operate

The safety valve should operate at about 10% above the set pressure. If this doesnot happen, adjust the pressure setting of the safety valve. Lift the manual handleto operate the safety valve sometimes this can get jammed after a few years if thevalve has not been operated or tested periodically, and lifting the valve manuallycan clear the jam.



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7.0 SERVICE & SPARES

7.1 Service Policy

Steamline has built its reputation and growth on only three pillars the knowledgeof our engineers, the quality of our products and most important of all, the quality ofour service, both before and after the order. While we take a lot of care to ensurethat you do not need service, by selecting the correct components, conductingrigorous inspections, dedicated manufacturing, testing and finishing, the reality ofphysics means that isolated failures can occur. What matters is how we deal withthem. All our engineers are continuously reminded that the reason we exist andcompete in a tough market is that we are available to our customer immediatelywhen there is a problem.

In case you have any grievance regarding the quality of service provided to you, or

of delays in service, please contact Mr. Vikram Jain at Steamline, Pune on phonenumber 020 2693 2213 or mobile number 98220 56160.

7.2 Warranty Repairs

The PRS / DSH / PRDSH unit has a 1 year warranty. We stock spares and othercomponents for immediate exchange after we have isolated the cause of theproblem. The parts will be immediately repaired or replaced in accordance with ourTest & Guarantee Certificate, free of charge. Any incidental charges includingexcise duty, freight, octroi etc. are payable by the client. Any costs incurred for thevisit of a service engineer shall be borne by Steamline.

Factory authorized repairs that are received for service will be returned within twoweeks. However, we can return the units quicker if the client pays courier charges.

Out of warranty repairs are done on a flat fee basis after the warranty has expired,or under the terms and conditions of a valid Annual Maintenance Contract.

7.3 Spare Parts

The following Steamline original spare parts are available:

Gaskets

Gasket Kit for complete PRS / PRDSH (Please specify PO No. or As built Drg. No.)

SS Mesh for StrainersPlease specify PO No. or As built Drg. No.

Control Valve DiaphragmsPlease specify actuator size this is stamped on the Control Valve.

Other PartsDisc or Spring of Safety ValveSeat or Plug of Control Valves



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7.4 Service Record

All service provided by Steamline engineers should be recorded in the Service

Record below, in order to provide continuity and knowledge of past actions to theService Engineer.

Product Model:

Serial No. :

Commissioned On :

In-warranty Service

Proposedvisit

Actual visit Actions Taken / Parts replaced (if any)

Free Visit 1 Date:

ServiceEngr.:

Sign:

Free Visit 2 Date:

ServiceEngr.:

Sign:

Free Visit 3 Date:

Service

Engr.:

Sign:



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Out of Warranty Service

Date of visit Problem

Reported

Actions Taken / Parts replaced (if any)

Date:

ServiceEngr.:

Sign:Date:

ServiceEngr.:

Sign:Date:

ServiceEngr.:

Sign:Date:

ServiceEngr.:

Sign:Date:

ServiceEngr.:

Sign:

Date:

ServiceEngr.:

Sign:



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8.0 NOTES
