HP & LP ByPass System in 600MW power plant

HP LP Bypass system provided to dump steam into condenser in emergency and start-up condition.

1. 1 HP/LP By Pass System

2. 1x600 MW JHABUA POWER LTD, SEONI, M.P 2 BY-PASS SYSTEM During short trip outs the supply of steam to turbine has to be totally cut off from the boiler. Once short tripping is over, turbine requires steam at high/rated temperature as the temperature of the turbine parts have not reduced much during the short period due to effective insulation and high mass of materials. But boiler will not give in a sudden during restart. If low temperature steam admitted, turbine will be affected. In other words, TPS will idle until the turbine cool and match with steam parameters. This period will be very long since cooling rate is very low for the turbine.

3. BY-PASS SYSTEM By pass system comprises a pipe work system with valves and pressure dropping devices to enable live steam from the boiler to by pass the turbine completely and be dumped into the condenser. For matching live steam and turbine metal temperature for a quick start-up , 3 1x600 MW JHABUA POWER LTD, SEONI, M.P

4. WHEN BY PASS IS REQUIRED During Startup and shutdown During a Turbine Trip (if any protection acts either internal or external) Higher Steam Pressure (Exceeding operating limit) 1x600 MW JHABUA POWER LTD, SEONI, M.P 4

5. WHEN and WHY STEM FLOW IS NECESSARY THROUGH REHEATER The higher steam temperature to required for IP Turbine during cold start –up. During sudden of turbine if bypass system comes in auto it will save from boiler tripping. In Reheater circuit steam flow required if flue gas temperature exceed above 540 Deg.C to Avoid failure of reheater tube. 1x600 MW JHABUA POWER LTD, SEONI, M.P 5

6. CLASSIFICATION OF BY PASS SYSTEM HP By Pass System 1x600 MW JHABUA POWER LTD, SEONI, M.P 6

7. Schematic Of HP And LP By Pass System 1x600 MW JHABUA POWER LTD, SEONI, M.P 7

8. HP Bypass Valve Design Pressure –176.7Ksc Design Temperature- 540 °C Combined pressure and de superheating Valve Spherical shaped body to optimize stress level Zero Leak Valve 1x600 MW JHABUA POWER LTD, SEONI, M.P 8

9. Operation Philosophy of HP bypass system Component of HP bypass System Primary bypass valve 1&2(BPV -1&2) Warm-Up Valve (BPV 3&4) HP bypass spray control Valve (BPE 1&2) Spray Station isolation valve HP Bypass oil supply unit 1x600 MW JHABUA POWER LTD, SEONI, M.P 9

10. Primary bypass valve 1&2(BPV -1&2 ) Operation Emergency Fast Open 1.Turbine Trip 2.Turbine loading shedding relay operated 3.Emergency push button operated from HMI 4.Control Deviation High(If MS pressure –HPBP set pressure) ->8Ksc 5. Generator Circuit Breaker Opened Fast Closing 1.HPBP Downstream Temperature Low (Selection Tx Basis ) >380 ° C 2. Condenser Vacuum Very Low (2/3 Tx ) > 0.6 Ksc 1x600 MW JHABUA POWER LTD, SEONI, M.P 10

11. HP Bypass CF Unit ON Permissive To CF Pump 1.CFP Discharge pressure Not Hi (Switch) < 180 Ksc 2.HPBP HPSU Tank Level Not Low (Switch) > Min 3.Oil Temperature Of Tank Not Hi (Switch) < 65 °C OFF Permissive To CF Pump 1.Oil temperature Of HPBP HPSU Tank Hi (Switch) > 65 °C 2. Oil Tank Level. V. low (Switch) < Min Auto “Start” of HPBP HPSU CFP-1 & 2 1.Selected pump On And Still Discharge Pressure low (Switch) Then Other Pump Auto On < 110 Ksc 2. If Running Pump Flow Low(Switch) Then Selection Will Be Changed & Pump Change-over Occurs TD=5 Sec Auto “Off” of HPBP HPSU CFP-1 & 2 1.Selected Pump On And Discharge Header Pressure V. Hi (Switch) Then Selected Pump Trips > 180 Ksc 2.Both CF Pumps-1 & 2 Running & Still Dis Header Pressure Low (Switch). Then Both Pump Trips < 110 Ksc TD 2Min 3. If Selected Pump Made On Then Auto Off Command Goes To Other Pump For 5 Sec. 4. If Selected Pump On & Stand-by Pump Started Due To Low Pressure And If Pressure Becomes Adequate Then Stand-by Pump Stops > 110 Ksc TD: 2 Min 1x600 MW JHABUA POWER LTD, SEONI, M.P 11

12. LP Bypass System 1x600 MW JHABUA POWER LTD, SEONI, M.P 12

13. LP Bypass System Oil Supply Unit 1x600 MW JHABUA POWER LTD, SEONI, M.P 13

14. LP Bypass Valve Design Pressure –27.34Ksc Design Temperature- 537 °C Each has been capable to pass 510T/ Hr Combined pressure and de superheating Valve Spherical shaped body to optimize stress level Zero Leak Valve 1x600 MW JHABUA POWER LTD, SEONI, M.P 14

15. Operation Philosophy of LP bypass system Component of LP bypass System Primary Bypass Stop valve 1&2 Primary Bypass control valve 1&2 LP bypass spray control Valve 1&2 Spray Station isolation valve LP Bypass oil supply unit 1x600 MW JHABUA POWER LTD, SEONI, M.P 15

16. LP bypass valve 1&2 Operation Emergency Fast Opening Of LPBP LP By Pass Trip Reset Condition S.N. Description Set Pt./TD 1. Turbine Trip   2. Emergency Open Button Pressed From HMI   S.N. Description Set Val/ T.D Alarm 1. LPBP-1 CH-1/CH-2 Trip Reset PB pressed from MMI/HMI OR     2. LPBP-1/2 CV-1/2 Position <-40 % <-40 %   1x600 MW JHABUA POWER LTD, SEONI, M.P 16

17. Protection OF LPBP S.N. Description Trip Value / T.D Alarm 1. LPBP-1 CH-1/CH-2 Trip Acted     a) Condenser-1 Wall Temp Protection >90 °C   b) LPBP Condenser-1 Protection Acted     i)   If Condenser-1 Pressure(2/3 Transmitters) Value Hi (LPBP CV-1 Starts Closing) And   >0.6 Ksc     ii) LPBP CV-1 Position Reaches < -40% (Then LPBP-1 ESV Closes) < -40 %   c) LPBP-1 CH-1/CH-2 Trip Operated (From MMI/HMI)     d) LPBP-1 EPB Operated From UCP     e) Water Injection Flow Protection: If Difference Between ( LPBP-1 Steam Flow – Water Injection Flow <Set Value And LPBP CV-1 Position < -40 % < 0 TPH TD:20 Sec   f) HPSU Emergency Off     i) Fire Protection I Operated OR     i) Fire Protection II Operated OR     iii) Emergency Push Button Pressed OR     iv) (HPSU Tank CF Level <170mm Or CF Temp. In HPSU > 65 Deg. C For More Than 25 Sec. OR     1x600 MW JHABUA POWER LTD, SEONI, M.P 17

18. Protection And interlock Of LPBP HPSU Unit For CFP SLC Auto Off Logic: S.N. Description Set Pt./TD 1. HPSU Auto Release:   a) LPBP-1 CH-1 & CH-2 Trip Reset And   b) LPBP-2 CH-1 & CH-2 Trip Reset And   c) CF Tank Level In LPBP HPSU Tank Not Low And >170 mm d) LPBP Pressure C.V. Position > - 40% 2. LPBP HPSU Emergency Off Should Not Be Present   1x600 MW JHABUA POWER LTD, SEONI, M.P 18

19. Protections (LPBP CFP-1 & 2) S.N. Description Trip Value / T.D Alarm   1. LPBP HPSU Dis. Hdr . Pressure V. Hi >250 Ksc   2. HPSU Emergency Off:     a) CF Tank Level In HPSU Tank Lo Or < 170 mm TD: 25 Sec   b) CF Tank Oil Temp Hi Or >65 °C TD: 25 Sec   c) EPB Pressed Or     d) Fire Protection CH-1 Operated Or     e) Fire Protection CH-2 Operated     1x600 MW JHABUA POWER LTD, SEONI, M.P 19

20. Auto Start of LPBP CFP-1: S.N. Description Set Pt./TD 1. SLC On & If CFP-2 Is Selected As Main Pump & Hdr Pressure Low < 201 Ksc 2. SLC On & LPBP CFP-2 Trips & CFP-2 MCC Disturbed for 2s   3. If SLC Is Made On, Both CFP-1 & 2 Will Get Auto On For 2 Sec.   4. If Pump-1 Is Selected As Main Pump And HPSU Hdr Pr. (< 245 Kg/Cm2), Pump On Command Will Go For 2 Sec And If HPSU Hdr Pr. ( > 250 Kg/Cm2) On Command Will Be Reset <245 Ksc 1x600 MW JHABUA POWER LTD, SEONI, M.P 20

21. Auto Start of LPBP CFP-2 S.N. Description Set Pt./TD 1. SLC On & If CFP-1 Is Selected As Main Pump & Hdr Pressure Low <201 Ksc 2. SLC On & LPBP CFP-1 Trips & CFP-1 MCC Disturbed for 2 s   3. If SLC Is Made On, Both CFP-1 & 2 Will Get Auto On For 2 Sec.   4. If Pump-2 Is Selected As Main Pump And HPSU Hdr Pr. (< 245 Kg/Cm2), Pump On Command Will Go For 2 Sec And If HPSU Hdr Pr. ( > 250 Kg/Cm2) On Command Will Be Reset < 245 Ksc 1x600 MW JHABUA POWER LTD, SEONI, M.P 21 1

22. Auto Stop of LPBP CFP-1: S.N. Description Set Pt./TD 1. If SLC Of CFP Is Switched Off   2. If SLC Of CFP Is On & CFP-1 MCC Disturbed   3. If CFP-1 & 2 On & HPSU Hdr . Pressure V. Low <120 Ksc TD: 2 Min 4. If SLC Of CFP Is On & Both CFP-1 & 2 running & CFP-2 Is Selected As Main Pump & Discharge Header Pressure Is Adequate >216 Ksc 1x600 MW JHABUA POWER LTD, SEONI, M.P 2 22

23. Auto Stop of LPBP CFP-2: S.N. Description Set Pt./TD 1. If SLC Of CFP Is Switched Off   2. If SLC Of CFP Is On & CFP-2 MCC Disturbed   3. If CFP-1 & 2 On & HPSU Hdr . Pressure V. Low <120 Ksc TD: 2 Min 4. If SLC Of CFP Is On & Both CFP-1 & 2 running & CFP-1 Is Selected As Main Pump & Discharge Header Pressure Is Adequate >216 Ksc 1x600 MW JHABUA POWER LTD, SEONI, M.P 23 3

24. Advantage Of Bypass System To cut down unit start up time To allow boiler operation during short turbine trip To warm up steam line during start up To give smooth warm up of boiler component including reheater . A most boiler run up may be possible. It is save fuel. Enable the boiler to take up heavy rejection trip to the house load operation advantageously Water loss during start up minimized Independent operation is achievable. 1x600 MW JHABUA POWER LTD, SEONI, M.P 24 4

25. Anant Deo Chaturvedi 1x600 MW JHABUA POWER LTD, SEONI, M.P 25