design memorandum for lp chemcial dosing system (rev-1)

8/15/2019 Design Memorandum for Lp Chemcial Dosing System (Rev-1)

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BHEL DOCUMENTS NO.: PE-DC-320-154-A001

DEPTT: MECHANICAL AUXILIARY

REV. NO. 1 DATE:

2X500 MW TPS CHANDRAPUR EXPANSION PROJECT. SHEET

DOCUMENT TITLE:

DESIGN PHILOSOPHY FOR

LP CHEMICAL DOSING SYSTEM.

suitably duplicated for which bidder shall provide free changeover contacts (1 NO + 1NC) rating0.25 amp. / 220 V DC, 5.0 Amp, 240 V AC at the local panel.

The ON / OFF commands for individual pumps from local push buttons shall act on therespective drives through DDC MIC.

The stroke position & adjustment will be done from DDC MIS and the stroke actuator shall besuitable for accepting 4-20 mA DC signal. The pumps shall be provided with 24 V DC, 2-wireLVDT Type position feed back transmitter to generate 4-20 mA DC signal to indicate strokeposition.

Following interlocks shall be provided. At Low level in the tank.

Running Dosing Pump shall be tripped.

Stirrer motor of the tank shall be tripped.

Following annunciation shall be provided in DDCMIS and LCP.

Running Dosing Pump trip.

Stirrer motor trip

Tank level low.

3.1.6 FLUSHING

Condensate tapped from Condensate water line shall be used for flushing the various pipeslines and pumps of the system as shown in P &I drawing.

3.2 AMMONIA DOSING SYSTEM :(TOTAL NO OF SKID= 2 NOS)(Refer drg no. PE-DG-320-154-A002)

Boiler feed water/Condensate water should have proper pH in order to protect the system fromcorrosion. In order to control the same dosing of dilute solution of Ammonia is done atCondensate discharge header at CPU outlet only. Though provision has been kept to doseammonia at Boiler Feed suction line immediately below the Deaerator storage tank,Condensate Transfer pump discharge header and Boiler filling line also, but dosing shall bedone at one place at a time. For this purpose one (1) no. skid mounted ammonia-dosing systemshall be provided. Dosing system shall mainly comprise the following:

3.2.1 SOLUTION PREPRATION CUM METERING TANK (1 No.)

A solution-preparation cum metering tank for preparation and measuring the dilute Ammoniasolution shall be provided. The tank shall be provided with accessories like motorized stirrer,breather with vent, level gauge, and level switch, overflow drain. A filling connection is providedto fill the concentrated solution by hand pump in the tank.The solution is then dosed to the required point with the help of dosing pumps.

3.2.2 AMMONIA DOSING PUMPS (TOTAL 2 NOS)


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3.2.5 CONTROL & INSTRUMENTATION

The normal mode of operation of Ammonia dosing system shall be from DDC MIS including ON/ OFF command to individual pumps. However, a local control panel consisting of Start Stoppush buttons, Indicating Lamp, Local / Remote selection, stroke position indicator, Rise / lowerpush button to stroke position, local annunciation to be mounted & stroke position indicator onthe lamp shall be provided.

The normal mode of operation of dosing system shall be through DDC MIS, Local remoteselection is to be done with from remote (CR) and indication for the same should be providedon local panel.

Local annunciation system shall be microprocessor based. All the local annunciations shall besuitably duplicated for which bidder shall provide free changeover contacts (1 NO + 1NC) rating0.25 amp. / 220 V DC, 5.0 Amp, 240 V AC at the local panel.

The ON / OFF commands for individual pumps from local push buttons shall act on therespective drives through DDC MIC.

The stroke position & adjustment will be done from DDC MIS and the stroke actuator shall besuitable for accepting 4-20 mA DC signal. The pumps shall be provided with 24 V DC, 2-wireLVDT Type position feed back transmitter to generate 4-20 mA DC signal to indicate strokeposition.

Following interlocks shall be provided. At Low level in the tank.

Running Dosing Pump shall be tripped.

Stirrer motor of the tank shall be tripped.

Following annunciation shall be provided in DDCMIS and LCP. Running Dosing Pump trip.

Stirrer motor trip

Tank level low.

3.3 NaOH DOSING SYSTEM: :(TOTAL NO OF SKID= 2 NOS)(Refer drg no. PE-DG-320-154-A003)

Sodium Hydroxide (NaOH) dosing system is provided to dose NaOH solution in Equipmentcooling water lines to increase pH upto 9.5. The sodium hydroxide dosing is done in the ECW

cycle during the initial fill and for the compensation of cooling water for any leakage duringnormal run. The 1% solution of NaOH is prepared manually by opening the inlet valve of DMwater and adding NaOH lye in basket. The NaOH is being dissolved by locally starting themotorized stirrer. The dosing is done manually as per requirements of desired pH in ECW line

judged by trial basis. Normally the leakage is occasionally and of small quantity . At the lowlevel of solution in tank the solution is to be prepared again.The dosing system consists of following.


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Running Stirrer motor of the tank shall be tripped.Following fault indications shall be provided in DDCMIS and LCP:

Stirrer motor trip

Tank level low.

3.2.5 FLUSHING

Condensate tapped from condensate line shall be used for flushing the various pipelines andpumps of the system as shown in P&I drawing.

4.0 DESIGN BASIS:

The following drawings/data sheets are enclosed for the reference:

PE-DG-320-154-A001 P&ID for Hydrazine dosing system.PE-DG-320-154-A002 P&ID for Ammonia dosing system.PE-DG-320-154-A003 P&ID for NaOH dosing system.DATA SHEET – A For above systems.

ANNEXURE-I Design Calculation for the above system.


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DATA SHEET – A

Sl no. Description HYDRAZINE DOSINGSYSTEM

AMMONIA DOSINGSYSTEM

NaOH DOSINGSYSTEM

1.1.0 No. of skids per unit One (1) One (1) One (1)

1.1.1 No. of skids per station Two (2) Two (2) Two (2)1.2.0 SOLUTION PREPARATION CUM METERING TANK

1.2.1 No. of tanks per Skid One (1) One (1) One (1)

1.2.2 Capacity 1200 Ltr. 1200 Ltr. 1000 Ltr.

1.2.3 Type Conical End. Conical End. Conical End.

1.2.4 Material of the tank SS-304 SS-304 SS-3041.2.5 Thickness 3 mm. 3 mm. 3 mm.

1.2.6 Motorised Stirrer/agitator Provided Provided ( Provided

1.2.7 Breather with vent Provided Provided Provided

1.2.8 Level switch Provided Provided Provided

1.2.9 Level gauge Provided Provided Provided

1.2.10 Hand pump with flexiblehose.

One (1) One (1) Not applicable.

Dissolving basket Not applicable. Not applicable. Provided

1.3.0 METERING PUMP 1.3.1 Type of pump Positive displacement (Plunger type) Not applicable.

1.3.2 Mode of control Manual Manual Not applicable.

1.3.3 No. of pumps motorassembly.

Two (2) nos. (2X100%) Two (2) nos. (2X100%) Not applicable.

1.3.4 Capacity (LPH) 0-50 LPH 0-50 LPH Not applicable.

1.3.5 Discharge pressure(Kg/Cm

2)

45 Kg/Cm 45 Kg/Cm Not applicable.

1.3.6 All Wetted parts of pumps. SS-304 SS-304 Not applicable.

1.4.0 STRAINERS Not applicable.

1.4.1 No. of strainers Two (2X100%) Two (2X100%) Not applicable.1.4.2 Type ‘Y’-Type ‘Y’-Type Not applicable.

1.4.3 Material of screen SS 304 SS 304 Not applicable.

1.4.4 Mesh Size 50(BS) 50(BS) Not applicable.

1.5.0 PIPING

1.5.1 Material SS-304 SS-304 SS-304

1.5.2 Material code ------------------ASTM A 312 TP 304 (Seamless)------

1.5.3 Diameter Main, Sampling & Drain Pipe-25 NB and Overflow pipe-25 NB

1.6.0 VALVES

1.6.1 Body, Cover, Yoke & TrimMaterial SS-304 SS-304 SS-304

1.6.2 Weld ends Socket weld ends Socket weld ends Socket weld ends1.7.0 Fittings Forged steel to A182 F304, Dimension to ANSI B 16.11 socket weld ends.

1.8.0 Structural steel IS 2062 IS 2062

1.9.0 Flanges – Pump suction /discharge

-----------------ANSI B 16.5 CL 150 / ANSI B 16.5 CL 300----

1 9 1 RATING


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DESIGN BASIS & CAPACITY SELECTION CRITERIA

HYDRAZINE DOSING

INPUT DATA

-MAX FLOW RATE AT DEARATOR OUTLET A T/HR 1720

-OPERATING PRESSURE AT DEARATOR OUTLET B KG/CM2(g) = 6.5

-DISSOLVED O2 AT DEARATOR OUTLET C ppm = 0.007

-NO. OF DEARATORS D No. = 1

-MAX FLOW RATE AT CEP DISCHARGE E M3/HR = 1386

-OPERATING PRESSURE AT CEP DISCHARGE F KG/CM2(g) = 26.5

-DISSOLVED O2 AT CEP DISCHARGE G ppm. = 0.021

-RESIDUAL HYDRAZINE AT HP/LP BFP DISCHARGE H ppm. = 0.02

-CONCENTRATION OF HYDRAZINE SOLUTION TO BE

DOSED

I % = 0.5

-PUMP INCREASED CAPACITY FACTOR K = 70

-CONCENTRATION OF HYDRAZINE IN MEASURING TANK CM % 35

-CAPACITY OF THE TANK REQUIRED FOR L Hrs. = 24

-MARGIN ASSUMED FOR TANKS FOR SIZING M % = 20

HYDRAZINE DOSING AT DEARATOR OUTLET

PUMP SIZING

QUANTITY OF HYDRAZINE REQUIRED (QH) Gm/Hr. = A(2*C+H)*50 / 32 = 91.38

VOLUMETRIC FLOW Ltrs. (VFH) LPH = QH / I*100 / 1000 = 18.28

DESIGN CALCULATION FOR 500 MW. (REV-1)

HENCE PUMP CAPACITY REQUIRED LPH = VFH * 100 / K = 26.11

PUMP SELECTED CAPACITY LPH = = 50

DISCHARGE PRESSURE OF PUMP SELECTED KG/CM2(g) = = 45.00

HYDRAZINE DOSING AT CEP DISCHARGE

PUMP SIZING

QUANTITY OF HYDRAZINE REQUIRED (QH) Gm/Hr. = E(2*G+H)*50 / 32 = 134.27

VOLUMETRIC FLOW Ltrs. (VFH) LPH = QH / I*100 / 1000 = 26.85




TANK SIZING

CAPACITY OF THE TANK REQUIRED MXS Ltrs. = MAX(VFH )*

L*D*(100+M)/100

= 773.39

CAPACITY OF THE TANK SELECTED (X) Ltrs. = = 1200.00

FINAL PARAMETERS SELECTED FOR HYDRAZINE DOSING


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AMMONIA DOSING

INPUT DATA

-MAX FLOW RATE AT DEARATOR OUTLET A M3/HR 1720

-OPERATING PRESSURE AT DEARATOR OUTLET B KG/CM2(g) = 6.5

-NO. OF DEARATORS D No. = 1

-MAX FLOW RATE AT CEP DISCHARGE E M3/HR = 1386

-OPERATING PRESSURE AT CEP DISCHARGE F KG/CM2(g) = 26.5

-AMMONIA DOSING RATE G PPM 0.25

-CONCENTRATION OF AMMONIA SOLUTION TO BE DOSED I % = 2

-CONCENTRATION OF AMMONIA SOLUTION IN

MEASURING TANK

O % = 30

-PUMP INCREASED CAPACITY FACTOR K = 70

-CAPACITY OF THE TANK REQUIRED FOR L Hrs. = 24

-MARGIN ASSUMED FOR TANKS FOR SIZING M % = 20

AMMONIA DOSING AT DEARATOR OUTLET

PUMP SIZING

QUANTITY OF AMMONIA REQUIRED (QH) Gm/Hr. = A * G = 430.00

VOLUMETRIC FLOW Ltrs. (VFH) LPH = QH *100 / I / 1000 = 21.50



AMMONIA DOSING AT CEP DISCHARGE

PUMP SIZING

QUANTITY OF AMMONIA REQUIRED (QH) Gm/Hr. = E * G = 346.50

VOLUMETRIC FLOW Ltrs. (VFH) Ltrs. = QH *100 / I / 1000 = 17.33




TANK SIZING

CAPACITY OF TANK REQUIRED (RX) Ltrs. = max(VFH) * L*D*M = 619.20

CAPACITY OF TANK SELECTED (X) Ltrs. = = 1200.00

FINAL PARAMETERS SELECTED FOR AMMONIA DOSING

PUMP CAPACITY (LPH) 50

PUMP PRESSURE Kg/CM2(g) 45

PREPERATION CUM METERING TANK CAPACITY (Ltrs.) 1200


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INPUT DATA

NORMAL FLOW RATE OF ECW LINES M3/HR = 3943

LEAKAGE FROM ECW LINE (SAY) % = 1

RATE OF SODIUM HYDROXIDE SOLUTION TO BE DOSED(NTPC RECOMM.) PPM=

2

STRENGTH OF NAOH SOLUTION TO BE PREPARED IN THE

TANK

% = 1

TANK SIZING

BASED ON LEAKAGE

TOTAL LEAKAGE OF WATER IN ONE HR M3 = 39.43

QUANTITIY OF 100% SODIUM HYDROXODE REQUIRED GR/HR = 78.86

VOLUME OF NAOH SOLUTION REQD GR = 7886

LTR 7.886

TANK SIZE REQUIRED FOR ONE DAY LTR = 189.26

TANK SIZE SELECTED LTR 500.00

BASED ON INITIAL FILLING IN ECW Cycles

VOLUME OF DM WATER IN ECW LINE FOR BOILER

AUXILIARY

M3 = 142

VOLUME OF DM WATER IN ECW TANK FOR BOILER

AUXILIARIES

M3 = 10

VOLUME OF DM WATER IN ECW LINE FOR TG AUXILIARY M3 = 101

VOLUME OF DM WATER IN ECW TANK FOR TG

AUXILIARIES

M3 = 10

MAX VOLUME OF DM WATER FOR PASSIVATION M3 = 263

QUANTITIY OF SODIUM HYDROXODE 100% REQUIRED GR = 526.00

VOLUME OF NAOH SOLUTION REQD GR = 52600

LTR = 52.6

DESIGN CALCULATION FOR SODIUM HYDROXIDE TANK

TANK SIZE SELECTED LTR = 1000.00

FINAL PARAMETERS SELECTED FOR SODIUM HYDROXIDE

DOSING SYSTEM

TANK CAPACITY (Ltr) = 1000


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design memorandum for lp chemcial dosing system (rev-1)

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