ERV Floating Procedure

PROCEDURE FOR ELECTROMATIC RELIEF VALVE FLOATING Document No: PWR/TSX/BLR/03/247/00 PWR/TSX/BLR/03/247/00/11 /11

Bharat Heavy Electricals Limited Power Sector: Technical Services Kribhco Bhawan, A-8-10, Sector 1, Noida, 201301

PROCEDURE FOR ELECTROMATIC RELIEF VALVE FLOATING

Content S. No.

Description

Page No.

1. Objective

4

2. Electromatic Relief Valve (ERV) Assembly, System & Terminology

4

3. ERV Floating Principle

7

4. Checks for ERV Floating (Mechanical & Electrical)

7

5. Pre – Floating Activity

8

6. Safety Precautions

8

7. Safety Equipments

8

8. Procedure for ERV Floating

9

9. ERV Setting Values

10

10. Appendix 1: ERV Details in a typical drawing for “Safety Valve Setting for Boiler, Superheater, Reheater & Soot Blower” for a 500 MW Boiler

11

Power Sector – Technical Services

Document No: PWR/TSX/BLR/03/247/00/11 -3-


1. Objective Electromatic Relief Valve (ERV) is provided in the system to prevent boiler pressure going beyond the required level at any load by operating it electrically from remote according to requirement and to prevent frequent operation of safety valves, thereby increasing its life and availability. ERV Floating is one of the last commissioning activities before boiler is ready for load operations. The objective of ERV Floating activity is to determine and ensure: Popping or Set Pressure for the ERVs Clean popping of the ERVs Reseating or Closing Pressure of the ERVs Clean reseating of the ERVs Blowdown for the ERVs Cleanliness of the ERVs and its exhaust system

2. ERV System, Assembly & Terminology Isolating Valve – Shown in Figure 1. It is the mechanical isolating gate valve provided for isolating ERV from the system. Pilot Valve – Shown in Figure 1. Pilot Valve is the main component of ERV which when operates relieves the pressure of the system. Solenoid Assembly – Shown in Figure 1. Solenoid gets energized from electrical supply via actuated pressure switch, which in turn operates the pilot valve. Control Station – Shown in Figure 1. Control Station is equipped with 3 point switch (manual, off and automatic) and corresponding 3 lamps (red, blue & green). Green light indicates auto position. Blue light indicates system pressure reaching the set point or corresponding relay for pressure switch has been energized at manual position. Red light glows, when the valve remains open fully at the time of floating. Hand operation is performed by putting the switch to manual position for opening and then to ‘off’ position for closing. Controller – Shown in Figure 1. Controller houses pressure switches for set & reseat pressure and get impulses through impulse line originating from MS Line. By adjusting the screws, the operating point (i.e. set pressure & blowdown) can be decided. Set Pressure – Pressure at which ERV starts floating. Basically, it is the gauge pressure at the valve inlet, for which the ERV is adjusted to open under service conditions. Reseat Pressure – Pressure at which ERV stops floating i.e. the pressure at which the disc reseats.



PROCEDURE FOR ELECTROMATIC RELIEF VALVE FLOATING Blow Down – It is the difference between set pressure and reseating pressure expressed as a percentage of the set pressure. It signifies the amount of pressure relieved from the system.

Blowdown (%) =

(Set Pressure – Reseat Pressure) * 100 Set Pressure

Figure 1: Electromatic Relief Valve System




Figure 2: Electromatic Relief Valve Assembly

Nomenclature List (for Figure 2)

226 229 303 305 307 311 322 323 324 332 341

Base Stud Nut Main Base Inlet Neck Support Plate Pilot Valve Tube Nipple Extension Discharge Collar Pipe Elbow Solenoid Assembly Seat Bushing – Main

344 345 347 351 355 356 376 377 378 379 383


Disc Guide Disc Spring Pilot Seat Bushing Pilot Disc Pilot Stem Pilot Spring Pipe ELL Pipe Nipple Lever Solenoid Plunger Head



3. ERV Floating Principle ERV Floating principle is explained below with the help of Figure 2 giving details of ERV Assembly. Steam under pressure from the superheater enters the main valve through the inlet chamber A, and passes upward around the disc guide, to chamber B, steam enters chamber C through the clearance space between the main valve disc (344) and its guide (345). The main valve disc (344) is held in the closed position by steam pressure in chamber C. the pressure in chamber c is the same as in chamber b when the escape through port D is prevented by the closure of the pilot valve disc (355). The pilot valve disc (355) is held in the closed position by pilot valve spring (347) and by the steam pressure in chamber E. It is opened by the operating lever (379) under the action of the solenoid plunger head (383). When the pilot valve is opened steam is released from chamber D through port F at a faster rate than supplied through the clearance space between the main valve disc and the main valve disc guide. The resultant unbalance of pressures in chambers B and C produces a force which moves the main valve disc from its seat, permitting steam to escape from chamber B to outlet G.

4. Checks for ERV Floating Mechanical Checks 

Visually inspect all the ERV for correction erection and installation as per drawing.



No load transmission from discharge piping to ERV.



Vertical installation (within ± 1˚).



Body drain to a safe area.



Adequate 360⁰ access around valve & overhead.



Controller away from location of vibration and several looping in impulse pipe.



Slope of impulse line towards the controller & provided with siphon.



Gap between solenoid plunger end and pilot valve operating lever is 22.7 to 35.4 mm.



Pressure connection at 8 to 10 pipe dia. upstream from ERV.

Electrical Checks 

Terminal connection correctness w.r.t. wiring diagram.



Installation of recommended fuses.



Power supply.



Cut off switch in solenoid for proper function.



Pressure switch for correct range.

 Smooth action of solenoid by pressing.




5. Pre – Floating Activity Close the ERV Isolating gate valve. Put the switch on ‘Auto’ and green light will indicate correctness. Turn the switch to ‘Manual’. Measure the movement of solenoid plunger. It should press the operating lever in such a way that pilot stem moves by 2.4 to 3.2 mm. Red and blue lamps should be glowing now. Blue lamp shows that relay is energized. Red light shows that plunger has reached the bottom of stroke i.e. the valve has opened. Put the switch back to ‘Auto’. Red & blue lights should go off. Solenoid & opera ting lever returns to normal position. Put the switch to ‘off’. All lights should go off.

6. Safety Precautions a) Do not stand in front of discharge side of an ERV during floating. b) Never install a ERV in a horizontal position, as they are designed for vertical operation only. Always provide Isolating Valve for ERV to isolate it from the system. c) Drains of ERV must be piped to a safe area. d) 360⁰ and overhead access to ERV should be there. e) Minimum number of people, only who are required for the floating & setting of ERV should be present on the ERV floor during the activity. f) Cordon off the area where valves are going to be tested to avoid trespassing during the activity and warn people at the site about the activity and precautions to be taken. g) Use safety equipments listed in the section of Safety Equipments for personnel safety from noise and high temperature during the activity.

7. Safety Equipments a) Asbestos Gloves b) Safety Helmet c) Ear Muffs d) Eye Protector e) Safety Shoes f) Protective Clothing g) First Aid Box (Containing – Eye Lotion, Tincture of Iodine, Burnol, Bandages, Cotton etc.)




8. Procedure for ERV Floating Light up the boiler following O&M instructions. Keep Main Steam Stop valve closed. Raise the pressure to 35 kg/cm² and hold. Disconnect the impulse line from controller and steam flush the line for 15 – 30 minutes by opening isolation valve. Restore back the impulse line. Open slightly the ERV isolation gate valve. Allow at least 30 minutes for warming up of valve. Open the isolation valve fully. If valve leakage is visible (it can happen due to entrapment of dirt or scale in seat), operate the switch on ‘Manual’ for few seconds. If the valve leakage persists even after 5 minutes of operation, valve seat requires rectification. Increase the boiler pressure. As the pressure increases, first the low pressure (closing pressure) switch indicating light will glow indicating its actuation. On further increase of pressure, ERV will pop. Note down the popping pressure & blow down. Check set pressure, reseat pressure and blowdown for the ERV in the Safety Valve Details Chart provided in the drawing “Safety Valve Setting for Boiler, Superheater, Reheater & Soot Blower” (Typical Drawing No.: 2 –00 –047 –XXXXX). A typical drawing for ERV Setting for 500 MW Boiler is enclosed in Appendix 1. If popping pressure is less than recommended, turn the corresponding setting screw counter clockwise. For decreasing popping pressure, turn it clock-wise. For setting blow down, the recommended graph (as in Figure 3) may be referred. By turning corresponding setting screw for blow down, same can be increased (clockwise) or decreased (counter clockwise).




Figure 3: Typical Graph for Setting Blowdown of SH ERV

9. ERV Setting Values A typical set of values for ERV Setting for a 500 MW Boiler is given in Table 1 as below. Table 1: Typical ERV Setting Values for a 500 MW Boiler S.No.

Location

Valve Tag No.

Valve Model No.

1. 2. 3. 4. 5. 6. 7. 8. 9.

Super Heater Super Heater Super Heater Super Heater Super Heater HRH HRH HRH HRH

SV9 SV10 SV11 SV12 SV13 SV22 SV23 SV24 SV25

CONSOL 1538 VX-10W CONSOL 1538 VX-10W CONSOL 1538 VX-10W CONSOL 1538 VX-10W CONSOL 1538 VX-10W CONSOL 1525 VX CONSOL 1525 VX CONSOL 1525 VX CONSOL 1525 VX


Valve Set Pressure Blowdown Type Of Valve 2 (in kg/cm ) (G) (%) OPEN CLOSE 185.5 180.3 2.8 ERV 185.5 180.3 2.8 ERV 186.6 180.6 3.2 ERV 186.6 180.6 3.2 ERV 186.6 180.6 3.2 ERV 48.4 47.1 2.7 ERV 48.4 47.1 2.7 ERV 48.9 47.6 2.7 ERV 48.9 47.6 2.7 ERV

Document No: PWR/TSX/BLR/03/247/00/11 - 10 -

Appendix 1: ERV Details in a typical drawing for “Safety Valve Setting for Boiler, Superheater, Reheater & Soot Blower” for a 500 MW Boiler

DISTRIBUTION LIST Regional / Other Heads ED, PS-NR, Noida ED, PS-ER, Kolkata ED, PS-WR, Nagpur ED, PS-SR, Chennai GM (I), CQ, Noida Regional Project Site Heads GM (PMX, CFX, MSX & IT), PS-NR GM(Anpara & Harduaganj), PS-NR GM (GGSR) , PS-NR GM(SCP, Commrcl), PS-NR GM (GVK Goindwal), PS-NR GM(Jhajjar), PS-NR GM (Pariccha), PS-NR GM(Bawana), PS-NR GM (TSX) , PS-NR GM (Dadri & Farakka), PS-NR GM (Nalco Damanjodi) , PS-SR GM (Vallur) , PS-SR GM (North Chennai) , PS-SR GM (Neyveli) , PS-SR GM (SAS) , PS-SR GM (Malwa) , PS-SR GM (Tuticorin) , PS-SR GM (Rihand & Vindhyachal), PS-WR GM (Pipavav) , PS-WR GM (Satpura) , PS-WR GM (Hazira) , PS-WR GM (Project & Pur) , PS-WR GM (Bina Power) , PS-WR GM (Project - I) , PS-ER GM (Project II) , PS-ER GM (Project III & IV) , PS-ER GM (Project V) , PS-ER GM (Project VI) , PS-ER GM (Project VII) , PS-ER GM (WBPDCL Projects) , PS-ER Regional Commissioning Heads AGM (TSX), PS-WR, Nagpur AGM (TSX), PS-SR, Chennai AGM (TSX), PS-NR, Noida AGM (TSX), PS-ER, Kolkata

For kind information

For kind information and wider circulation among Site Engineers

For kind information and wider circulation among Commissioning Engineers

Regional Service Center Heads RSM – Noida RSM – Chandigarh RSM – Varanasi RSM – Nagpur RSM – Baroda RSM – Secunderabad RSM – Patna Engineering Heads/Others AGM (Engg.), BHEL – Hyd GM (I) (Engg.), BHEL – Trichy GM (Engg – FB), BHEL – Trichy AGM (FES-FBC & HRSG), BHEL – Trichy AGM (Engg-FBC & HRSG),BHEL – Trichy Regional Project Site In-charge/ Construction Manager CM, Barsingsar, PS-NR CM, Bawana, PS-NR CM, Chabbra, PS-NR CM, Dariba, PS-NR CM, Dadri, PS-NR CM, Jhajjar, PS-NR CM, Farakka, PS-NR CM, Anpara D, PS-NR CM, GVK Goindwal, PS-NR CM, Harduaganj Extn, PS-NR CM, Kosti, Sudan, PS-NR CM, GGSR Refinery, PS-NR CM, LM Bhatinda, PS-NR CM, Obra, PS-NR CM ,Parichha, PS-NR CM, Abhijit, PS-ER CM, Adhunik, PS-ER CM, Bakreshwar, PS-ER CM, Baramura, PS-ER CM, Bongai RPL , PS-ER CM, Barauni IOC, PS-ER CM, Barauni TPS, PS-ER CM, Barh Stage II, PS-ER CM, Bokaro A, PS-ER CM, Chandrapura, PS-ER CM, Durgapur, PS-ER

For kind information and distribution to service engineers


For kind information and wider circulation among Site Engineers

CM, Haldia (IOCL & HMC) , PS-ER CM, IISCO Burnpur Project, Asansol, PS-ER CM, Kahalgaon STPP, PS-ER CM, Korba West, PS-ER CM, Koderma, PS-ER CM, Lakwa, PS-ER CM, Lepetkata, PS-ER CM, Maithon, PS-ER CM, Marwa, PS-ER CM, Mejia, PS-ER CM, MTPP-Kanti, PS-ER CM, NTPC Bongaigaon, PS-ER CM, Paltana, PS-ER CM, Santaldih, PS-ER CM, Sidhriganj, Bangladesh, PS-ER CM, TISCO - Jamshedpur, PS-ER CM, Teesta, PS-ER CM, Vizag, PS-ER CM, Bharuch, PS-WR CM, Bhusawal, PS-WR CM,BORL Bina, PS-WR CM, Bina Power, PS-WR CM, Bhilai, PS-WR CM, Hazira, PS-WR CM, Hindalco Mahan, PS-WR CM,HZL, PS-WR CM,IOCL (IRUP) , PS-WR CM,JPL Raigarh, PS-WR CM, Khaperkheda, PS-WR CM, Korba, PS-WR CM, Paras, PS-WR CM, New Parli, PS-WR CM, Kutch Lignite, PS-WR CM, Monnet Ispat Project, PS-WR CM, Nagothane, PS-WR CM, Chandrapur, PS-WR CM, Pipavav – Amreli, PS-WR CM, Sikka, PS-WR CM, SLPP Mangrol, PS-WR CM, Sulaymaneyah, PS-WR CM, Ukai # 6, PS-WR CM, SAIL Rourkela, PS-WR CM, India Bulls, PS-WR

CM, Avantha Power - 1, PS-WR CM, Avantha Power – 2, PS-WR CM, Rihand-5 & 6, PS-WR CM, Amarkantak, PS-SR CM, Bellary, PS-SR CM, RINL Vizag, PS-SR CM,HPCL Vizag, PS-SR CM, Kakatiya, PS-SR CM, Kalwakurthy, PS-SR CM, Kothagudem, PS-SR CM, KRL Kochi, PS-SR CM, Kundakulam, PS-SR CM, Kuttiyadi (Kerala) , PS-SR CM, Muddanur, PS-SR CM, Nalco CPP, PS-SR CM, Nalco Damanjodi, PS-SR CM, Nettampad, PS-SR CM, Neyveli, PS-SR CM, NINL Duburi, PS-SR CM, North Chennai Stage II, PS-SR CM, Raichur, PS-SR CM, Simhadri Stage II, PS-SR CM, Sipat, PS-SR CM, Vallur, PS-SR

Safety In-charge DGM- QLY & HSE, PS-ER AGM-FEX, PS-NR

Management Representatives AGM (Quality & IT), PSNR – Noida SDGM (Quality), PSWR – Nagpur AGM (Quality & PLC), PSER – Kolkata AGM (Quality) SR – Chennai Power Sector - Technical Services GM (PT & ADMIN) GM (TS)



ERV Floating Procedure

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