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Steam turbine deaerating condenser perforamace improvement

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I have attached this report where we find out the actual reason steam turbine Deaerating Condenser Performance degradation which was written on June 06, 2012.That time I was in Haripur Power Limited (HPL) ,A 360 MW CCPP of Pendekar Energy Bangladesh Ltd.

The report outcome showed that the Steam turbine load could be reached to its maximum capacity after those valve maintenance works on the next Steam Turbine Major inspection on 2013.We hope we can increase our steam turbine load to 5-7 MW/D on that time.
The operational guys were indicating Circulating water pumps (CWP A&B) were not performing to its design capacity & Ejectors/vacuum pumps are not performing well.So,Mechanical Maintenance Team (MMT) team find this successful outcome after several study.


Condenser vacuum condition has improved a lot after maintenance of the valves on last Major Inspection on 2013.
It is a sample report where we can realize that identifying actual reason for an equipment performance is not only a job of operational people but also a responsibility of the maintenance guys.

Published in: Education, Business

Steam turbine deaerating condenser perforamace improvement

  1. 1. Deaerating Condenser Performance Improvement Report June 06, 2012 Prepared by Ashik Ahmed Maintenance Engineer In a Multinational Power Plant Email: ashik_rofy@yahoo.com,ashik.rofy@gmail.com Mobile: +880-173-0059920 LP Cylinder Exhaust Hood Neck Transition Piece Shell Tube Bundle Air Extraction Points Page Hot well 1 Water box division
  2. 2. THE STEAM TURBINE SPECIFICATION:REACTION REHEAT CONDENSING TYPE TWO CASING DOUBLE FLOW EXHAUST RATED OUTPUT 131,600 KW RATED SPEED 3,000 RPM MAIN STEAM PRESSURE 100 BAR A MAIN STEAM TEMPERATURE 565 ºC REHEAT STEAM PRESSURE 29.9 BAR A REHEAT STEAM TEMP. 565 ºC EXHAUST PRESSURE 0.060 BAR A MANUFACTURER: FUJI ELECTRIC PROBLEM:Absolute Pressure of Condenser Vacuum remains -697.24 (mmHg) but the value was -705 (mmHg) in few years back. So, the Steam turbine load can’t be operated to its maximum capacity. In the same time the water temperature Difference Between inlet & Outlet on Water Box-B Side shows ~2°c whereas temperature Diff. Between inlet & Outlet on Water Box-A Side shows ~5.4°c.The temperature difference should be quite near as they are handling the same condensate steam from Steam Turbine. POSSIBLE REASONS:Air Leakage Circulating water pumps (CWP) are not performing to its design capacity. Ejectors/vacuum pumps are not performing well Some extra steam load on condenser water box-A side cause the ∆T is extremely higher. Page 3 *** At first let we all try to understand what a Deaerating condenser. Some portions of next III pages are collected from a presentation of an unknown author (Probably a presentation of the former owner of this plant AES; during their commissioning time in Bangladesh).As it is very important for our understanding; I have included some portion (Literatures) of that presentation in to this report. ***
  3. 3. WHAT ARE FUNCTIONS OF DEAERATING CONDENSER? Provide a heat sink within which to condense, and so recycle, the high quality feedwater allow increased heat/work transfer across the steam turbine by reducing the LP Turbine exhaust steam conditions Remove dissolved oxygen and non -condensable gases from the steam /condensate COMPONENTS OF THE CONDENSER The condenser is a single pressure, two pass, vertically divided water box design with its entire condensing surface (8,806 m2) in a single rectangular shell. Cooling Water, supplied from the Main Cooling Water System flows (CWP Maker:KSB) through the condenser tubes. Steam, expanded in the steam turbine, exhausts into the neck of the condenser through exhaust openings located after the final stages of the LP cylinder/Turbine. The steam then flows through the transition piece to the tube bundles located lower in the shell. Cooling water flows through the tube bundles. Steam cooled and condensed on the outside of the condenser tubes falls to the hot well located at the bottom of the condenser. The condensate is returned to the Steam/water cycle by the condensate extraction pumps (CEP Maker:KSB). The condensing steam reduces significantly in volume creating a reduced pressure in the condenser. The degree of negative pressure is dependent on the cooling water temperature which in turn affects the steam vapor pressure and temperature. Excess air is removed from the condenser steam space initially by the condenser vacuum pumps and any subsequent air and non condensable gases migrating into the condenser are removed by these pumps LP Cylinder Exhaust Hood Neck Transition Piece Shell Tube Bundle Air Extraction Points Hot well FIGURE 1 SIMPLIFIED DIAGRAM OF CONDENSER SHOWING TWO PASS Page 3 Water box division
  4. 4. CONNECTIONS TO THE CONDENSER The following connections are made to the Condenser through the condenser flash box.              Cold Reheat Steam Dump Line HP Connection Pipe Drains MCV Downstream Drains ICV Upstream Drains HP/IP Outer Casing Drains HP/IP Inner Casing Drain HP/IP Balance Pipe Drain HP Front Gland Drain Turbine Gland Steam Header Drain LP Admission Steam Pipe Drain ACV Drain CRH Steam Check Valve Front Drain Flash Tank Drain It can be seen that all the turbine drains taken to the flash box are from a point downstream of the main HP, IP and LP Steam Isolating Valves. COOLING WATER CIRCUIT The cooling water circuit provides the heat exchange medium within the condenser. River Water is pumped through the condenser tubes by cooling water pump (CWP). Steam condenses on the outside of the tubes. The cooling water flow through the condenser produces a syphonic effect once the pipe work is fully charged with water; this in turn causes a negative pressure to appear at the outlet water boxes. The condenser cooling water outlet conduit is taken to a seal pit, which provides a fixed atmospheric breakpoint in the system. This ensures that during normal operation the pressure at the outlet water boxes, although negative, will remain above the vaporization pressure associated with the outlet temperature of the cooling water. Page 4 The Inlet, Return and Outlet Water boxes of the condenser are divided into two separate sections. Each section is served by independent inlet and outlet isolating valves. As a two pass circuit the water flows into the bottom or inlet water boxes, passes through a nest or bundle of tubes (lower quadrants) to the reversal or return water boxes, where it reverses direction and rises to the upper quadrants of the condenser before flowing through a second tube bundle to the outlet water boxes.
  5. 5. Exhaust Steam from LP Turbine Upper Quadrants-Outlet Hot Water Send back to River after proper Heat Transfer Lower Quadrants-Inlet DEAERATING CONDENSER CWP -A CWP -B Relatively Cold water taken From River FIGURE 2 COOLING WATER CIRCUIT CONDENSER PERFORMANCE DEPENDS ON FOLLOWING PARAMETER MONITORING:During normal operation regular checks of the following parameters should be made and the values logged:      STG Load Air Leakage Inlet Cooling Water Temperature Outlet Cooling Water Temperature Absolute Pressure in Condenser ( Condenser Vacuum) The following values should be calculated and logged: Page The Cooling Water Temperature Rise is calculated from the difference between Cooling Water Outlet and Inlet Temperatures. The Initial Temperature Difference is calculated by first determining the steam saturation temperature for the current Condenser Pressure and the subtracting the Cooling Water Inlet Temperature. 5 The Cooling Water Temperature Rise Initial Temperature Difference Terminal Temperature Difference
  6. 6. NOW WE WILL TRY TO FIND OUT THE POSSIBLE SOLUTION FOR CONDENSER VACUUM PROBLEM & SEVERE TEMPERATURE DIFFERENCE BETWEEN WATER BOX A & B. HISTORY OF CONDENSER  The Ejector erection was completed, commissioned and kept on operation on 14.08.04. 1st time both the ejector & vacuum pumps operation had started on 15.03.08.  Before that the condenser vacuum was maintained with either vacuum pump or ejector.  All vacuum pumps & ejector are in operation from 21.03.11 to till date.  The temperature difference between cooling water in/out on water box A & B had started from 07.10.11. CONDENSER DETAILS: DEAERATING CONDENSER Code: HEI (Ninth Edition) Heat Duty 799.1´106 KJ/h Empty Weight 165000 P.O. No. HAC-0004M-´-30466 Surface Area - 8806 m² Hot well Capacity- 35.3 m³ Operating Weight- 310 000 kg Mfg. Serial No.HE-00-026 Shell side Design Pressure 1.013 / F.V bar. A Design Temp.36.18 / 36.18 ºC Fluid: Steam Flow Rate : 357500 kg/h Hydro Test: Full of Water Tube side 3.5 / F.V bar. A 25 / 30.49 ºC River Water 34680000kg/h 5.25 Page  Extra loading to the condenser.(Valve passing)  Air ingression to the condenser.  Performance degradation of CWP pump.  Performance degradation of Ejector & vacuum pumps.  Temperature difference between condenser A & B side. i) Extra loading to the condenser.(Valve passing) Case:-I) The IP bypass stop valve HV-336B & PCV-336B has got huge passing. The IP bypass line PCV 336B was found passing on the last CI2012.Continuous condensate was found on that line. The line ends over the tubes of condenser A side. The condensate pressure was 4 bar that time, while on normal running condition the R/H outlet pressure is over 28 bar. The condenser inlet temperature (TE-336C) was found 196˚c on normal running condition. The temperature reduced to 150˚c while stopping the stop valve HV-336.But the stop valve also got passing that’s why the temperature didn’t come down. 6 Condenser Performance Degradation probable cause:
  7. 7. Case:-II) HIP turbine drain valve 045A,045B.045D & 045 I was showing huge passing .The temperature on the downstream of this valves was observed (139.4°c ,245.3°c ,282.3°c & 504.2°c ).Whereas the other valves are having temp <45°c . This passing high temperature steams goes to the flash box, ultimately raising the temperature of the condenser water box. Case:-III) The drain valves of MOV-320c have got huge passing. The CEP discharge to the flash tank TCV-033E got 93% opening. Later on after closing the upstream isolation valve of MOV-320c,the TCV-033E Opening reduced to 43%. Case:-IV) The MOV-020(A, B, C &D) the HP SPR HTR & R/H outlet drain to the flash tank got some passing too. As the flash tank cep discharge TCV-033E opening also reduced a bit after closing the upper isolation valves. ii) Air Ingression to the Condenser The Crack over the IP Bypass line near spray water injection point could be checked again. The blind flange of condenser shell side shows loose bolts. All other line flange could be inspected through soap bubble test for finding air ingression. Page 7 III) Performance degradation of CWP pump.
  8. 8. We can see from the technical data sheet that the flow will be increased on the increase of water level. CIRCULATING WATER PUMP:- CIRCULATING WATER PUMP MOTOR – Hyundai Made:- Hyundai 3 Phase induction motor, Model 1350VKNM Type: HLA7 902-36Y Serial No.KA0366-CWP-001 1100 KW, 12P, 6600 V 134.7 Amp Tag No. CW-M-PP-03-1 494 RPM, Efficiency : 94% Capacity 18,600 cu.m/hr. CosΦ :0.76 Total head 16m HPL overall, P.F, CosΦ =0.80 Design temp. 25 ºC Power (Bhp) 1100 Kw Speed 493 rpm CALCULATION:Date : 18.06.12 Given:CWP-A Current :- 109 A, Dish. Pr: 1.02Bar , Inside Water Level:- 7120 mm,Voltage: 6600 v Motor efficiency: 94% Assuming Pump efficiency on 85 % Assuming frictional loss =2 feet HPL overall, P.F, CosΦ =0.80 So, Motor Power = √3 x V x I x CosΦ =1.732 x 6600 x 114 x 0.80 = 104.25 KW So ,the Bhp = Motor Power x Efficiency of motor /0.746 =104.25 x 0.94/0.746 =1313.637 Hp The head of the pump,(feet)= pump discharge pressure (in abs) ± Suction head + friction loss H =(1.01325+1.09) x 14.7 x 2.31/specific gravity – (7.12-1.1) x 3.28+ 2 = 71.45 – 19.74+ 2 = 53.71 Feet We know Flow,Q= 3960 x ή x BHP H 3960 x 0.85 x 1313.637 53.71 = 82325.67 gal/min Or,we know Flow,Q= 550 x ή x BHP γH 550 x.85 x 1313.637 62.4 x 53.71 =183.238 feet3/sec = 18679.4 m3/hr =18698.19 m3/hr Page 8 The Cooling Water Pump flow is found up to the requirement; so can omit this from our cause list.
  9. 9.  iv) Performance degradation of Ejector & vacuum pumps. We can see from the cooling water inlet temperature the vaccum will be 696 mmhg at cooling water inlet temp 32°c. Absolute pressure = atm pressure+ gauge pr. So, 0.085 bara= 1.01325 + gauge pr. Gauge pressure = 0.085 - 1.01325 = - 0.92825 bar = - 696mmHg We found the same vacuum on 16.06.10.So the ejectors & vacuum pumps are performing well.  v) Temperature difference between water box A & b Page **PLEASE SEE THE WATER BOX A & B INLET & OUTLET DATA ON NEXT PAGES FOR YOUR BETTER UNDERSTANDING.** 9 The condenser tube cleaning was done on CI-2012 & there was no significant variations on tubes were observed that time. So, either extra load is on A side or the circulating water is flowing less on water box A side. As the IP bypass line is just over the condenser water box A side, so there is a huge possibility of temperature increase.
  10. 10. Several Data were taken on 5th & 6th Feb'12 on various discharge valve opening position due to Temperature Varience on Condeser Box A & B.. They are as follows:Condenser A Side Serial No Date Time Cooling Water Inlet Temp°C (A Side) TE-048A Cooling Water Outlet Temp°C (A Side) TE-048F Temp Differ °C (OutletInlet 5.8 5.6 5.7 5.3 5.5 5.8 7.1 6.9 7.2 1 2 3 4 5 6 7 8 9 10 12:44:11 12:48:43 12:49:00 05.02.12 14:24:28 14:28:26 14:30:20 5:26:27 6:26:03 06.02.12 7:25:40 13:42:32 22.2 22.2 22.2 22.3 22.3 22.3 22.2 22.2 22.2 22.5 28 27.8 27.9 27.6 27.8 28.1 29.3 29.1 29.4 28.5 11 15:04:24 22.6 29.1 Condenser B Side Pressure PT-048CA (Bar) Discharge Valve Opening % Cooling Water Inlet Temp°C (B Side) TE-048B Cooling Water Outlet Temp°C (B Side) TE-048G 25.1 25.2 25.3 26.6 26.3 26 27.3 27.9 26.7 58.2 58.2 58.2 58.3 58.3 40.6 6 0.72 0.78 0.79 0.76 0.71 0.77 0.71 0.79 0.8 0.71 62.7 62.8 43.4 62.4 22.4 22.4 22.5 22.6 22.7 22.6 22.4 22.3 22.4 22.7 6.5 0.91 37.5 22.9 Discharge Valve Opening % Seal Well Temp°C Vacuum mmHg (─) GTG Load MW STG Load MW Total Load MW 0.72 0.82 0.83 0.79 0.72 0.76 0.71 0.81 0.8 0.72 58.2 39.3 39.3 39.2 58.5 58.5 24.5 24.8 24.5 24.9 25.1 25 31.6 31.7 30.8 694.5 694.3 694.4 693.8 693.9 693.8 702.6 702.8 702.3 693.1 81.1 81.3 81.5 81 81.8 81 125.3 125.6 110.6 76.6 229.4 228.9 231.2 229.6 230.3 228.8 380.6 384.5 329.6 25.1 148.3 147.6 149.7 148.6 148.5 147.8 255.3 258.9 219 135.7 0.92 39.8 26.3 693.3 136.4 76.6 213 Temp Differ °C (OutletInlet) Pressure PT-048CB (Bar) 26.6 2.7 2.8 2.8 4 3.6 3.4 4.9 5.6 4.3 3.9 27.1 4.2 61.9 44.2 61.7 61.6 212.3 At 6th Feb 15:04 pm the vent line was open on both sides. The discharge valve was opened slowly & until water came out from the vent lines. Water didn't come from (048BA) discharge A side vent even on 37.5 % opening. As the CWP-A vibration was too high (Near 8.9 mm/s) ,the discharge valve didn't close more. Water came on rest of the valves:- I) Suction vent line of A side (048CA),II) Suction vent line of B side (048CB) & III) discharge vent line of B side (048DB). It is seen from the data that when the ST load is above (110~125 MW) or Total load is above (329~380MW) the seal well temperature became higher than the cooling water return temperatures (After the Condenser).Theoretically it is not possible until unless the following causes:● The thermocouples of return line (TE-048F & TE-048G) not functioning properly above 30°C OR ● Any underground pipe line near seal wall OR ● Any other operation causes. Remarks:The cooling water return temperature of Water box-A is higher than Water Box-B. As water is not coming even closing the water box-A discharge valve near 30% opening So, Top tubes of Condenser – A side is not getting water. ►As the cleaning will be carried out on Outage 2012, the answers could be found after inspecting the scale formation on the Water Box –A side top tubes. ►It could be assumed that the scale formation on Condenser water box-A is higher then the B side. ►As well as the opening of suction & discharge valves of the Condenser water box could be checked on the outage. ►Any steam leakage on A side where the The condenser inlet of IP bypass just above the tube bundles.
  11. 11. Steam Turbine Condenser Vacuum Several Years Data on Several Steam turbine load & cooling water inlet & outlet temperature Water Water Box Water Box Box A Inlet Pr.A Outlet Pr.B Inlet Bar Bar Temp. °c Water Box A Outlet Temp °c . Date Ejector Vacuum Pump Ambient Temp Condenser Vacuum (mmHg) PT-032A 14.08.04 05.04.06 07.05.06 10.06.06 17.07.06 20.12.06 25.01.07 28.04.07(N) 01.08.07 16.12.07 16.01.08 24.02.08 14.03.08 In Service Isolated In Service In Service In Service In Service In Service In Service Isolated Isolated Isolated Isolated Isolated In Service Isolated Isolated Isolated Isolated Isolated Isolated In Service In Service (A, B & C) In Service (A& B) In Service (B) 27 23 26 31 20 16 27 28 20 20 21 28 -694.6 -690.1 -703.9 -698 -706.5 -721.8 -690.4 -699 -709 -696 -707 -705 231.5/53.0/350.5 245.1/46.6/361.3 248.1/45.5/308.3 237.8/50.3/375.3 249/55/337 257.4/52.1/340.1 226/55.7/384.5 247/46/359 241/31/328 233/42/325 252.8/53.6/355.1 227.6/41.4/316.2 15.03.08 In Service In Service (B) 28 -705 251.6/45.5/335.9 114 41.8 0.86 0.88 27.2 31.03.08 17.07.08 23.11.08 23 11 08 24.11.08 09.12.08 10.12.08 12.12.08 31.12.08 In Service In Service In Service In Service In Service In Service In Service In Service In Service (B) In Service (B) In Service (C) In Service (A & C) Isolated In Service (A, B & C) Isolated Isolated 28 31 21 21 21 21 22 18 -697 -702.8 -692 692 -687 -706 -692 -699.3 -709.2 262/48.9/326 251.3/46.9/317.4 247/54/343 230/43/318 198/50/277 214/68/359 257.3/39.3/321.4 240.5/43.8/350 122 123 125 108 93 105 118 120 43.8 41.9 43 44.2 38.1 43.2 40.6 38.3 0.78 0.83 0.69 0 69 0.5 0.68 0.69 0.74 0.66 0.79 0.85 0.7 07 0.51 0.69 0.69 0.74 0.67 30 29 27 27 27 26.9 27.1 23.5 36.3 35 33 35 30 29 32.2 28.5 19.04.09(D) In Service Isolated 30.8 -684.3 270.2/48.8/365.3 120 45.7 0.61 0.62 33.4 19.04.09(N) 20.04.09(D) 20.04.09(N) In Service In Service In Service In Service (A, B & C) In Service (A & C) In Service (A, B & C) 29.9 31.1 29 -685 -683.8 -685 233/43/313 224/48.2/354.7 233/43/313 106 122 116 45.2 45.9 45.2 0.54 0.58 0.54 0.58 0.59 0.58 18.01.10 In Service In Service (A) 13.4 -712.3 252/51/340 127 35.8 0.68 04.04.10 21.08.10 23.12.10 19.03.11 21.03.11 30.07.11 27.09.11 05.10.11 In Service In Service In Service In Service In Service In Service In Service In Service In Service (A & C) In Service (B) In Service (C) In Service (A & B) In Service (A, B & C) In Service (A, B & C) In Service (A, B & C) In Service (A, B & C) 29.3 29.7 17.2 27 27.3 30.4 21.9 26.6 -693.5 -692.1 -706 -700 -699.2 -695 -690 -685.6 267/47/352 260/52/364 242.0/53.4/321.0 247/49/138 271.3/52.0/337.7 246/49/340 245/53/371 245.2/48.6/319.4 260/49/54 242.8/46.8/53.8 122 124 117 119 122 119 123 112 42.7 42.9 38.1 40.5 40.7 43.6 44 44.7 07.10.11 In Service In Service (A, B & C) 31.5 -682.9 257.3/49.8/337.9 258.9/46.4/52.3 121 17.10.11 In Service In Service (A, B & C) 28 -676.5 222/42/306 224/42/49 19.10.11 In Service In Service (A, B & C) 27.8 -680.9 182/38/292 23.10.11 In Service In Service (A, B & C) 26.5 -689.1 25.12.11 In Service In Service (A, B & C) 13.1 -704.6 Water Box B Inlet Temp. °c Water Box B Outlet Temp. °c 33.6 HP/IP/LP Feed Water Flow (Ton/hr) HP/IP/LP Feed Steam Flow (Ton/hr) S/T Load MW Condenser Temp TE(033EA) °c Ejector erection completed, commissioned and kept on operation. All outage preparation done. 116 43.7 0.71 0.7 30.6 35.7 30.7 118 45.7 0.74 0.75 32.2 36.3 32.3 119 41.4 0.74 0.75 28.9 33.3 28.9 120 43.2 0.78 0.8 30.4 34.8 30.5 123 40.1 0.74 0.76 25.9 31.6 25.9 122 35.8 0.71 0.72 20.9 26.5 21.3 123 44.1 0.79 0.82 30.4 35.6 30.4 121 40.4 0.72 0.74 27.6 32.6 27.5 121 39.3 0.69 0.7 24.1 29 0 115 41.4 0.86 0.88 22.8 29.8 0 126 38.9 0.66 0.63 22.4 25 0 110 41.5 0.78 0.79 27.3 33.3 5.1 4.1 4.4 4.4 5.7 5.6 5.2 5 4.9 7 2.6 6 5 5.2 2.4 3.9 4.8 4.8 5 3.3 0 0 0 0 6.4 0 6.3 6 6 8 3 2.1 5.1 5 38.1 4.7 0 34 33.4 34 38 38.2 38 4 4.8 4 0 0 0 0.69 21.2 26.9 5.7 0 0.68 0.69 0.71 0.67 0.68 0.72 0.72 0.77 0.69 0.7 0.72 0.68 0.69 0.74 0.74 0.8 30.7 30.3 22.8 25.4 25.6 31.1 30 31.7 35.3 35.2 27.9 29.7 29.2 34.8 35.62 36.8 30.34 31.65 34.67 36 4.6 4.9 5.1 4.3 3.6 3.7 5.62 5.1 0 0 0 0 0 0 4.33 4.35 45.8 0.72 0.74 31.51 36.56 31.39 34 5.05 2.61 100 48 0.77 0.79 31.27 36.09 31.39 34.01 4.82 2.62 203/232/45 89 46 0.69 0.7 30.58 35.8 31.39 34.01 5.22 2.62 207/42/292 212/39/46 95 44 0.7 0.71 30.4 36.19 30.53 32.21 5.79 1.68 193/42/291 214/231/46 100 38.9 0.78 0.8 22.1 28.2 6.1 0 Remarks 0 6 0 0 0 0 0 0 29 35.7 37.5 31.3 34.4 30.7 26.1 35.4 30.8 0 0 0 Condens er IP By Diff. Betn Diff. Betn pass line inlet & inlet & Inlet Outlet on Outlet on Temp A Side B Side (TE°c °c 336C) °c 35 rom the 1st time both the ejector & vacuum pumps are in operation ST gland steam pressure is high probably due to the passing through pressure control valve. Ejector air valve and steam line has been closed due to vacuum fall in low load. The temperature difference between cooling water in/out on water box A & B has started the leakage steam were coming out from the upper side of welding joint crack and the joint is up of the Spray hose. Crack IP Bypass line near spray water injection point has been repaired by welding. IP by-pass PCV was opened to 10% to check vacuum and condenser temperature difference. But no vacuum was increased.
  12. 12. Date Ejector Vacuum Pump Ambient Temp Condenser Vacuum (mmHg) PT-032A 22.02.12 19.03.12 In Service In Service In Service (A, B & C) In Service (A, B & C) 19.9 26.3 -698.5 -694.5 255/51/386 192/39/269 20.03.12 In Service In Service (A, B & C) 27.6 -685.6 21.03.12 In Service In Service (A, B & C) 25.9 27.03.12 25.04.12 11.05.12 05.06.12 10.03.12 10.06.12 11.06.12 In Service In Service In Service In Service In Service In Service In Service In Service In Service In Service In Service In Service In Service In Service (A, B & C) (A, B & C) (A, B & C) (A, B & C) (A, B & C) (A, B & C) (A, B & C) 12.06.12 In Service 12.06.12 12.06.12 12.06.12 Water Water Box Water Box Box A Inlet Pr.A Outlet Pr.B Inlet Bar Bar Temp. °c Water Box A Outlet Temp °c . Water Box B Inlet Temp. °c Water Box B Outlet Temp. °c 24.5 30 S/T Load MW Condenser Temp TE(033EA) °c 197/211/42 123 89 41.4 42.1 0.69 0.65 0.71 0.68 24.5 27.8 27 32.8 194/40/281 197/211/42 87 44.4 0.69 0.7 28 -685 203/42/256 204/38/45 91 44.2 0.68 0.72 28.7 31.9 31.8 24.1 30.3 32.4 33.1 -696.2 -689.6 -683.9 -685.4 -691.51 -693 -692.1 228/53/358 186.6/45.7/340.9 251.1/50.1/338.9 235.2/46.5/336.9 258/48/321 240/51/356 243.0/48.4/320.1 258/275/51 121 102 117 111 120 117 117 43.5 44.3 44.9 44.8 46.1 45.3 46.3 0.68 0.67 0.69 0.74 0.64 0.65 0.66 In Service (A, B & C) 33.19 -691.3 119.1 46 In Service In Service (A, B & C) 35.59 -698.9 119.6 In Service In Service (A, B & C) 36.9 -700.4 112 In Service In Service (A, B & C) 36.8 -701.2 117 14.06.12 In Service In Service (A, B & C) 32.41 -691.27 120.56 14.06.12 In Service In Service (A, B & C) 36.3 -688.044 116.36 14.06.12 In Service In Service (A, B & C) 36.16 -688.79 118.32 46.86 HP/IP/LP Feed Water Flow (Ton/hr) HP/IP/LP Feed Steam Flow (Ton/hr) 256/48/52 252.6/45.1/255 Condens er IP By Diff. Betn Diff. Betn pass line inlet & inlet & Inlet Outlet on Outlet on Temp A Side B Side (TE°c °c 336C) °c 2.5 5 5.5 0 32.1 4.1 0 28 32.6 4.6 0 0.72 0.7 0.71 0.76 0.66 0.68 0.685 29.3 31.3 31.6 31.4 32.7 31.6 32.9 35.4 36.6 37.2 37 38.1 36.8 38.1 6.1 5.3 5.6 5.6 5.4 5.2 5.2 0 0 0 0 0 0 0 0.63 0.66 32.5 37.9 32.8 34.8 5.4 2 194.56 45.7 0.65 0.68 32.2 37.6 32.4 34.6 5.4 2.2 191.36 45.5 0.62 0.65 32.3 37.6 32.5 34.3 5.3 1.8 187.12 46.1 0.65 0.67 32.7 38.1 32.8 34.8 5.4 2 186.16 45.92 32.65 38.09 32.79 34.7 5.44 1.91 192.2 46.36 33.09 38.59 33.44 35.28 5.5 1.84 188 33.25 38.63 33.38 35.38 5.38 2 45 Ejector HP/IP nozzle replacement work is going on. Ejector put back in service after HP & IP nozzles replacement. Vacuum was increased from 684.3 mmHg to -692.5 mmHg & ST load from 90 MW to 91.6 MW. 14.06.12 In Service In Service (A, B & C) 30.74 -689.38 119.5 46.89 33.54 38.77 33.81 35.81 5.23 2 196 16.06.12 In Service In Service (A, B & C) 26.51 -695 120.79 46 32.46 37.87 32.61 34.64 5.41 2.03 196 16.06.12 In Service In Service (A, B & C) 26.06 -697 121.51 45.63 31.75 37.21 31.84 34.12 5.46 2.28 192 16.06.12 In Service In Service (A, B & C) 26.52 -696.97 121.58 45.45 31.68 37.17 31.9 33.96 5.49 2.06 165 16.06.12 In Service In Service (A, B & C) 26.52 -696.97 121.58 45.45 31.68 37.17 31.9 33.96 5.49 2.06 160 16.06.12 In Service In Service (A, B & C) 25.66 16.06.12 In Service In Service (A, B & C) 26.52 12.06.12 -697.24 Service (A, B & C) Remarks 121.75 45.38 31.54 37.15 31.78 33.96 33.85 2.18 152 122.23 45.38 31.54 37.15 31.78 33.85 5.61 2.07 150.8 On IP by pass valve close & stop valve open position At 09:40 A.M On IP by pass valve close & stop valve close position At 12:07P.M On IP by pass valve close & stop valve close position At 13:59P.M On IP by pass valve close & stop valve close position At 15:26P.M On IP by pass valve close & stop valve open position At 09:00AM On IP by pass valve & stop valve close position At 14 PM On IP by pass PCV& stop valve close position as well as neck spray to the PCV for decrease of temp. on TE_336C At 16:00 PM On normal condition IP bypass PCV close & stop valve open condition . At: 22PM On IP by pass valve close & stop valve open position At 09:00AM On IP by pass valve & stop valve close position At 14 PM On IP by pass valve & stop valve close position At 15 PM On IP by pass valve & stop valve close position At 15 PM On IP by pass valve & stop valve close position At 16 PM On IP by pass valve & stop valve close position At 16:45PM The temperature on the IP bypass line(SB-001-FBD-750-P75 ) inlet on condenser (TE-336C) was showing 243.2 deg at 09:40 am in 12th June,2012.& the vacuum was -691.3 mmHg that time. The IP bypass line PCV 336B was found passing on the last CI-2012.Continuous condensate was found on that line. The line ends over the tubes of condenser A side. So the stop valve HV 336B was also stopped on 12th June 2012.The temperature decreased to 232.7 Deg & the vacuum found -701.2 mmHg on 15:26 pm on 12th June,2012. So the vacuum raise 10 mmHg due to the the reduction of probable passing on the PCV 336B. On 14th June,2012 the stop valve was again closed for vacuum improvement. But no significant rise of vacuum was observed. 14.06.12 The neck spray was manually operated that time & the condenser IP bypass line inlet temperature TE-336C was reduced from 200°c to 45 °c .The vent line of cooling water inlet was also vented. But no significant vacuum improvement was observed.
  13. 13. Date Ejector Vacuum Pump Ambient Temp Condenser Vacuum (mmHg) PT-032A HP/IP/LP Feed Water Flow (Ton/hr) HP/IP/LP Feed Steam Flow (Ton/hr) S/T Load MW Condenser Temp TE(033EA) °c Water Water Box Water Box Box A Inlet Pr.A Outlet Pr.B Inlet Bar Bar Temp. °c Water Box A Outlet Temp °c . Water Box B Inlet Temp. °c Water Box B Outlet Temp. °c Condens er IP By Diff. Betn Diff. Betn pass line inlet & inlet & Inlet Outlet on Outlet on Temp A Side B Side (TE°c °c 336C) °c Remarks The upper isolation valve of HP super heater drain MOV 020A & B was manually closed. Some improvement on flash box was observed. Then the R/H outlet drain valve 320C's upstream isolation valve was manually colsed.The flash tank tank huge improvement was observerd.The cep discharge to flash tank TCV-033E was 92 % opened before the operation.After that the TCV was reduced to opening 44%. 16.06.12 then the PCV-336B & HV-336B was closed again .The condenser inlet of IP bypass (TE-336C) was 196°c then it had reduced to 153°c .The probable passing on IP bypass stop valve also. HIP turbine drain valve 045A,045B.045D & 045 I was showing huge passing .The temperature on the downstream of this valve was observed (139.4°c ,245.3°c ,282.3°c & 504.2°c ).Whereas the other valves are having temp <45°c . (*All of this operation was done with the help,suggesstion of Operation people *) 17.06.12 The IP bypass stop valve XV-336 & PCV-336B could be calibrated with the help of IC& E. The main stop valve is not closing properly as the condenser inlet temperature (TE-336C) is not reducing a lot. HIP turbine drain valve 045A,045B.045D & 045 got huge passing. The upstream isolation valves of MOV-320c,020A & B have got passing. The HP super heater drain line to condenser XV-045H might got passing. The blind flange of condenser shell side shows loose bolts. It should be tightened on convenient time eith proper scaffolding. All other line flange would be inspected through soap bubble test. The cooling water inlet vent lines to the condenser will be opened.
  14. 14. CONCLUSION Probable Cause (I) :Air Leakage from condenser shell side. Answer:- We have to check all the flanges sealing condition by soap bubble test. Probable Cause (II) :Circulating water pumps (CWP) are not performing to its design capacity. Answer:- The current running data proves that the Cooling Water Pumps (CWP- A& B) are running still good though they are 12 years old. Probable Cause (III):Ejectors/vacuum pumps are not performing well. Answer:- The analysis shows the ejectors & vacuum pumps still are well enough for the operation. Probable Cause (IV):Some extra steam load on condenser water box-A side cause the ∆T is extremely higher. Answer:The IP bypass stop valve HV-336B & PCV-336B has got huge passing. The IP bypass line PCV 336B was found passing on the last CI-2012.Continuous condensate was found on that line. The line ends over the tubes of condenser A side. The condensate pressure was 4 bar that time, while on normal running condition the R/H outlet pressure is over 28 bar. HIP turbine drain valve 045A, 045B.045D & 045 got huge passing. The upstream isolation valves of MOV-320c, 020A & B have got passing. So, this is the probable cause of condenser under performance for the last few years. I hope the Steam turbine load can be reached to its maximum capacity after those valve maintenance works on the next Steam Turbine Major inspection on 2013.We hope we can increase our steam turbine load to 5-7 MW/D on that time. Thank You All Page I would also like to thank our operation team cause they have help us a lot also for problem finding. So, it’s a combined effort I believe & hope this report will be helpful for our Steam Turbine Capacity improvement after next MI-2013 & we can operate Steam Turbine like before. 14 This total report is a combined effort from our Haripur Power Limited (HPL) mechanical maintenance team. I want to thank our MMT Manager Mr. Zahid Hossain & MMT Supervisor Mr. AB Siddique for their continuous support.

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