Steam turbine deaerating condenser perforamace improvement

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Deaerating Condenser Performance Improvement Report

June 06, 2012

Prepared byAshik Ahmed

Maintenance EngineerIn a Multinational Power Plant

Email: [email protected],[email protected]: +880-173-0059920

LP Cylinder

Neck

Transition Piece

Shell

Tube Bundle

Hot well

Exhaust Hood

Water box division

Air Extraction Points

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THE STEAM TURBINE SPECIFICATION:-

REACTION REHEAT CONDENSING TYPE TWO CASING DOUBLE FLOW EXHAUSTRATED OUTPUT 131,600 KWRATED SPEED 3,000 RPMMAIN STEAM PRESSURE 100 BAR AMAIN STEAM TEMPERATURE 565 ºCREHEAT STEAM PRESSURE 29.9 BAR AREHEAT STEAM TEMP. 565 ºCEXHAUST PRESSURE 0.060 BAR AMANUFACTURER: 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 LeakageCirculating water pumps (CWP) are not performing to its design capacity.Ejectors/vacuum pumps are not performing wellSome extra steam load on condenser water box-A side cause the ∆T is extremely higher.

*** At first let we all try to understand what a Deaerating condenser. Some portions of next III pagesare 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. ***

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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

Neck

Transition Piece

Shell

Tube Bundle

Hot well

Exhaust Hood

Water box

division

Air Extraction

Points

FIGURE 1 SIMPLIFIED DIAGRAM OF CONDENSER SHOWING TWO PASS

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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. 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.

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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: The Cooling Water Temperature Rise Initial Temperature Difference Terminal Temperature Difference 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.

Lower Quadrants-Inlet

Upper Quadrants-Outlet

Hot Water Send back to River after proper Heat Transfer

Relatively Cold water taken From River

DEAERATING CONDENSER

Exhaust Steam from LP Turbine

FIGURE 2 COOLING WATER CIRCUIT

CWP

-A CWP

-B

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NOW WE WILL TRY TO FIND OUT THE POSSIBLE SOLUTION FOR CONDENSER VACUUM PROBLEM & SEVERE TEMPERATURE DIFFERENCE BETWEEN WATER BOX A & B.

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 Tube side Design Pressure 1.013 / F.V bar. A 3.5 / F.V bar. A Design Temp.36.18 / 36.18 ºC 25 / 30.49 ºC Fluid: Steam River Water Flow Rate : 357500 kg/h 34680000kg/h Hydro Test: Full of Water 5.25

Condenser Performance Degradation probable cause:

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 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. 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.

HISTORY OF CONDENSER

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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.

III) Performance degradation of CWP pump.

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We can see from the technical data sheet that the flow will be increased on the increase of water level. CIRCULATING WATER PUMP:- Made:- Hyundai Model 1350VKNM Serial No.KA0366-CWP-001 Tag No. CW-M-PP-03-1 Capacity 18,600 cu.m/hr. Total head 16m Design temp. 25 ºC Power (Bhp) 1100 Kw Speed 493 rpm

CIRCULATING WATER PUMP MOTOR –

Hyundai 3 Phase induction motor, Type: HLA7 902-36Y 1100 KW, 12P, 6600 V 134.7 Amp 494 RPM, Efficiency : 94% CosΦ :0.76 HPL overall, P.F, CosΦ =0.80

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 =18698.19 m3/hr

Or,we know Flow,Q= 550 x ή x BHP γ H 550 x.85 x 1313.637 62.4 x 53.71 =183.238 feet3/sec = 18679.4 m3/hr

The Cooling Water Pump flow is found up to the requirement; so can omit this from our cause list.

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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

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.

**PLEASE SEE THE WATER BOX A & B INLET & OUTLET DATA ON NEXT PAGES FOR YOUR BETTER UNDERSTANDING.**

Cooling Water Inlet

Temp°C (A Side)TE-048A

Cooling Water Outlet

Temp°C (A Side)TE-048F

Temp Differ °C (Outlet-

Inlet

PressurePT-048CA

(Bar)

Discharge Valve

Opening%

Cooling Water Inlet

Temp°C (B Side)TE-048B

Cooling Water Outlet

Temp°C (B Side)TE-048G

Temp Differ °C (Outlet-

Inlet)

PressurePT-048CB

(Bar)

Discharge Valve

Opening%

1 12:44:11 22.2 28 5.8 0.72 58.2 22.4 25.1 2.7 0.72 58.2 24.5 694.5 148.3 81.1 229.42 12:48:43 22.2 27.8 5.6 0.78 58.2 22.4 25.2 2.8 0.82 39.3 24.8 694.3 147.6 81.3 228.93 12:49:00 22.2 27.9 5.7 0.79 58.2 22.5 25.3 2.8 0.83 39.3 24.5 694.4 149.7 81.5 231.24 14:24:28 22.3 27.6 5.3 0.76 58.3 22.6 26.6 4 0.79 39.2 24.9 693.8 148.6 81 229.65 14:28:26 22.3 27.8 5.5 0.71 58.3 22.7 26.3 3.6 0.72 58.5 25.1 693.9 148.5 81.8 230.36 14:30:20 22.3 28.1 5.8 0.77 40.6 22.6 26 3.4 0.76 58.5 25 693.8 147.8 81 228.87 5:26:27 22.2 29.3 7.1 0.71 62.7 22.4 27.3 4.9 0.71 61.9 31.6 702.6 255.3 125.3 380.68 6:26:03 22.2 29.1 6.9 0.79 62.8 22.3 27.9 5.6 0.81 44.2 31.7 702.8 258.9 125.6 384.59 7:25:40 22.2 29.4 7.2 0.8 43.4 22.4 26.7 4.3 0.8 61.7 30.8 702.3 219 110.6 329.610 13:42:32 22.5 28.5 6 0.71 62.4 22.7 26.6 3.9 0.72 61.6 25.1 693.1 135.7 76.6 212.3

11 15:04:24 22.6 29.1 6.5 0.91 37.5 22.9 27.1 4.2 0.92 39.8 26.3 693.3 136.4 76.6 213

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.

TotalLoadMW

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:-

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.

05.02.12

06.02.12

GTG LoadMW

STGLoadMW

Condenser B Side

Seal Well

Temp°C

Vacuum mmHg

(─)

Condenser A Side

Serial No

Date Time

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 LoadMW

Condenser Temp

TE(033EA)°c

Water Box Inlet Pr.A

Bar

Water Box Outlet Pr.B

Bar

Water Box AInlet

Temp.°c

Water Box AOutlet Temp

°c .

Water Box BInlet

Temp.°c

Water Box BOutlet Temp.

°c

Diff. Betn inlet &

Outlet on A Side

°c

Diff. Betn inlet &

Outlet on B Side

°c

Condenser IP By pass line

Inlet Temp(TE-

336C)°c

Remarks

14.08.0405.04.06 In Service Isolated 27 -694.6 231.5/53.0/350.5 116 43.7 0.71 0.7 30.6 35.7 30.7 35.7 5.1 507.05.06 Isolated In Service 23 -690.1 245.1/46.6/361.3 118 45.7 0.74 0.75 32.2 36.3 32.3 37.5 4.1 5.210.06.06 In Service Isolated 26 -703.9 248.1/45.5/308.3 119 41.4 0.74 0.75 28.9 33.3 28.9 31.3 4.4 2.417.07.06 In Service Isolated 31 -698 237.8/50.3/375.3 120 43.2 0.78 0.8 30.4 34.8 30.5 34.4 4.4 3.920.12.06 In Service Isolated 20 -706.5 249/55/337 123 40.1 0.74 0.76 25.9 31.6 25.9 30.7 5.7 4.8 rom the 25.01.07 In Service Isolated 16 -721.8 257.4/52.1/340.1 122 35.8 0.71 0.72 20.9 26.5 21.3 26.1 5.6 4.8

28.04.07(N) In Service Isolated 27 -690.4 226/55.7/384.5 123 44.1 0.79 0.82 30.4 35.6 30.4 35.4 5.2 501.08.07 In Service Isolated 28 -699 247/46/359 121 40.4 0.72 0.74 27.6 32.6 27.5 30.8 5 3.316.12.07 Isolated In Service 20 -709 241/31/328 121 39.3 0.69 0.7 24.1 29 0 0 4.9 016.01.08 Isolated In Service (A, B & C) 20 -696 233/42/325 115 41.4 0.86 0.88 22.8 29.8 0 0 7 024.02.08 Isolated In Service (A& B) 21 -707 252.8/53.6/355.1 126 38.9 0.66 0.63 22.4 25 0 0 2.6 014.03.08 Isolated In Service (B) 28 -705 227.6/41.4/316.2 110 41.5 0.78 0.79 27.3 33.3 6 0

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 33.6 6.4 0 1st time both the ejector & vacuum pumps are in operation

31.03.08 In Service In Service (B) 28 -697 262/48.9/326 122 43.8 0.78 0.79 30 36.3 6.3 017.07.08 In Service In Service (B) 31 -702.8 251.3/46.9/317.4 123 41.9 0.83 0.85 29 35 29 35 6 623 11 08 In Service In Service (C) 21 692 247/54/343 125 43 0 69 0 7 27 33 6 0

Ejector erection completed, commissioned and kept on operation. All outage preparation done.

Steam Turbine Condenser Vacuum Several Years Data on Several Steam turbine load & cooling water inlet & outlet temperature

23.11.08 In Service In Service (C) 21 -692 247/54/343 125 43 0.69 0.7 27 33 6 024.11.08 In Service In Service (A & C) 21 -687 230/43/318 108 44.2 0.5 0.51 27 35 8 009.12.08 In Service Isolated 21 -706 198/50/277 93 38.1 0.68 0.69 27 30 3 010.12.08 In Service In Service (A, B & C) 21 -692 214/68/359 105 43.2 0.69 0.69 26.9 29 2.1 012.12.08 In Service Isolated 22 -699.3 257.3/39.3/321.4 118 40.6 0.74 0.74 27.1 32.2 5.1 031.12.08 In Service Isolated 18 -709.2 240.5/43.8/350 120 38.3 0.66 0.67 23.5 28.5 5 0

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 38.1 4.7 0ST gland steam pressure is high

probably due to the passing through pressure control valve.

19.04.09(N) In Service In Service (A, B & C) 29.9 -685 233/43/313 106 45.2 0.54 0.58 34 38 4 020.04.09(D) In Service In Service (A & C) 31.1 -683.8 224/48.2/354.7 122 45.9 0.58 0.59 33.4 38.2 4.8 020.04.09(N) In Service In Service (A, B & C) 29 -685 233/43/313 116 45.2 0.54 0.58 34 38 4 0

18.01.10 In Service In Service (A) 13.4 -712.3 252/51/340 127 35.8 0.68 0.69 21.2 26.9 5.7 0Ejector air valve and steam line

has been closed due to vacuum fall in low load.

04.04.10 In Service In Service (A & C) 29.3 -693.5 267/47/352 122 42.7 0.68 0.69 30.7 35.3 4.6 021.08.10 In Service In Service (B) 29.7 -692.1 260/52/364 124 42.9 0.69 0.7 30.3 35.2 4.9 023.12.10 In Service In Service (C) 17.2 -706 242.0/53.4/321.0 117 38.1 0.71 0.72 22.8 27.9 5.1 019.03.11 In Service In Service (A & B) 27 -700 247/49/138 119 40.5 0.67 0.68 25.4 29.7 4.3 021.03.11 In Service In Service (A, B & C) 27.3 -699.2 271.3/52.0/337.7 122 40.7 0.68 0.69 25.6 29.2 3.6 030.07.11 In Service In Service (A, B & C) 30.4 -695 246/49/340 119 43.6 0.72 0.74 31.1 34.8 3.7 027.09.11 In Service In Service (A, B & C) 21.9 -690 245/53/371 260/49/54 123 44 0.72 0.74 30 35.62 30.34 34.67 5.62 4.3305.10.11 In Service In Service (A, B & C) 26.6 -685.6 245.2/48.6/319.4 242.8/46.8/53.8 112 44.7 0.77 0.8 31.7 36.8 31.65 36 5.1 4.35

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 45.8 0.72 0.74 31.51 36.56 31.39 34 5.05 2.61 The temperature difference between cooling water in/out on water box A & B has started

17.10.11 In Service In Service (A, B & C) 28 -676.5 222/42/306 224/42/49 100 48 0.77 0.79 31.27 36.09 31.39 34.01 4.82 2.62the leakage steam were coming

out from the upper side of welding joint crack and the joint is up of the Spray hose.

19.10.11 In Service In Service (A, B & C) 27.8 -680.9 182/38/292 203/232/45 89 46 0.69 0.7 30.58 35.8 31.39 34.01 5.22 2.62Crack IP Bypass line near spray water injection point has been

repaired by welding.

23.10.11 In Service In Service (A, B & C) 26.5 -689.1 207/42/292 212/39/46 95 44 0.7 0.71 30.4 36.19 30.53 32.21 5.79 1.68

IP by-pass PCV was opened to 10% to check vacuum and condenser

temperature difference. But no vacuum was increased.

25.12.11 In Service In Service (A, B & C) 13.1 -704.6 193/42/291 214/231/46 100 38.9 0.78 0.8 22.1 28.2 6.1 0


Ambient Temp



(Ton/hr)


(Ton/hr)

S/T LoadMW

Condenser Temp

TE(033EA)°c


Bar


Bar

Water Box AInlet

Temp.°c


°c .

Water Box BInlet

Temp.°c


°c

Diff. Betn inlet &

Outlet on A Side

°c

Diff. Betn inlet &

Outlet on B Side

°c


Inlet Temp(TE-

336C)°c

Remarks

22.02.12 In Service In Service (A, B & C) 19.9 -698.5 255/51/386 123 41.4 0.69 0.71 24.5 27 24.5 30 2.5 5.519.03.12 In Service In Service (A, B & C) 26.3 -694.5 192/39/269 197/211/42 89 42.1 0.65 0.68 27.8 32.8 5 0

20.03.12 In Service In Service (A, B & C) 27.6 -685.6 194/40/281 197/211/42 87 44.4 0.69 0.7 28 32.1 4.1 0 Ejector HP/IP nozzle replacement work is going on.

21.03.12 In Service In Service (A, B & C) 25.9 -685 203/42/256 204/38/45 91 44.2 0.68 0.72 28 32.6 4.6 0

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.27.03.12 In Service In Service (A, B & C) 28.7 -696.2 228/53/358 258/275/51 121 43.5 0.68 0.72 29.3 35.4 6.1 025.04.12 In Service In Service (A, B & C) 31.9 -689.6 186.6/45.7/340.9 102 44.3 0.67 0.7 31.3 36.6 5.3 011.05.12 In Service In Service (A, B & C) 31.8 -683.9 251.1/50.1/338.9 117 44.9 0.69 0.71 31.6 37.2 5.6 005.06.12 In Service In Service (A, B & C) 24.1 -685.4 235.2/46.5/336.9 111 44.8 0.74 0.76 31.4 37 5.6 010.03.12 In Service In Service (A, B & C) 30.3 -691.51 258/48/321 120 46.1 0.64 0.66 32.7 38.1 5.4 010.06.12 In Service In Service (A, B & C) 32.4 -693 240/51/356 256/48/52 117 45.3 0.65 0.68 31.6 36.8 5.2 011.06.12 In Service In Service (A, B & C) 33.1 -692.1 243.0/48.4/320.1 252.6/45.1/255 117 46.3 0.66 0.685 32.9 38.1 5.2 0

12.06.12 In Service In Service (A, B & C) 33.19 -691.3 119.1 46 0.63 0.66 32.5 37.9 32.8 34.8 5.4 2 194.56 On IP by pass valve close & stop valve open position At 09:40 A.M

12.06.12 In Service In Service (A, B & C) 35.59 -698.9 119.6 45.7 0.65 0.68 32.2 37.6 32.4 34.6 5.4 2.2 191.36 On IP by pass valve close & stop valve close position At 12:07P.M

12.06.12 In Service In Service (A, B & C) 36.9 -700.4 112 45.5 0.62 0.65 32.3 37.6 32.5 34.3 5.3 1.8 187.12 On IP by pass valve close & stop valve close position At 13:59P.M

12.06.12 In Service In Service (A, B & C) 36.8 -701.2 117 46.1 0.65 0.67 32.7 38.1 32.8 34.8 5.4 2 186.16 On IP by pass valve close & stop valve close position At 15:26P.M

On IP by pass valve close &14.06.12 In Service In Service (A, B & C) 32.41 -691.27 120.56 45.92 32.65 38.09 32.79 34.7 5.44 1.91 192.2 On IP by pass valve close & stop valve open position At 09:00AM

14.06.12 In Service In Service (A, B & C) 36.3 -688.044 116.36 46.36 33.09 38.59 33.44 35.28 5.5 1.84 188 On IP by pass valve & stop valve close position At 14 PM

14.06.12 In Service In Service (A, B & C) 36.16 -688.79 118.32 46.86 33.25 38.63 33.38 35.38 5.38 2 45

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

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 On normal condition IP bypass PCV close & stop valve open condition . At: 22PM

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 On IP by pass valve close & stop valve open position At 09:00AM

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 On IP by pass valve & stop valve close position At 14 PM




16.06.12 In Service In Service (A, B & C) 26.52 Service (A, B & C) 122.23 45.38 31.54 37.15 31.78 33.85 5.61 2.07 150.8 On IP by pass valve & stop valve close position At 16:45PM

12.06.12

14.06.12

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.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.


Ambient Temp



(Ton/hr)


(Ton/hr)

S/T LoadMW

Condenser Temp

TE(033EA)°c


Bar


Bar

Water Box AInlet

Temp.°c


°c .

Water Box BInlet

Temp.°c


°c

Diff. Betn inlet &

Outlet on A Side

°c

Diff. Betn inlet &

Outlet on B Side

°c


Inlet Temp(TE-

336C)°c

Remarks

16.06.12

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.

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%.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 *)

Pag

e14

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. 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. 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. Thank You All

Date post:	16-May-2015
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Steam turbine deaerating condenser perforamace improvement

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