Letter Template Dated 14.04.07 . Mimbai. Dear Sir, Please note, after having read / analysed all the reports, there are a few things I want to clarify. Do correct me if some facts are missing / misunderstood.

PROBLEM BEING FACED 1. Misfiring  Pilot burner fires smoothly.  Main burner FO fuel cut-off valve & recirculation valve operate at correct time.  FO pump pressure is steady at 20bar,  The Nozzle pressure does not build up.  The main flame does not catch.  Flame eye sensing no flame, initiates signal to shutdown boiler. Now, the boiler has been fired by manually opening bypass valve of auto flow regulating valve & flow transmitter to build up initial F.O pressure at the burner nozzle during start up. After stabilizing the main flame, flow regulating valve is maintaining the FO pressure according to the Load.

CHECKS / CHANGES MADE IN FUEL SYSTEM 1. Checked the air supply for the Valtor oil shut off valves. This must be minimum 5 bar, to secure that these are operated quick enough – Found satisfactory. 2. Checked the flow meter – Found satisfactory. 3. Checked the calibration of I/P converter – Found satisfactory. Changes made to Oil Flow Control valve :-  Cv changed from 1.2 (existing value) to 0.8 as recommended.  Screw number 16 adjusted until the flow valve is about to open.

4. Suspecting initial programming of the SIPART DR 24 – Air / Oil Controller not done correctly. Changes made in parameters (Instruction from Aalborg) :- a. PL09 (Set point for oil controller ignition position )= 023 = 23% is OK. Increased to 0.28 = 28%. b. Increase cP and reduce tn will make the controller Ccn1 quicker – in the air-oil zip file is writter 0.136 and 3.000 - try cP = upwards by using green arrow up (see controller setting in green display) towards 0.200 and see how things react.

Aalborg Boiler - Air / Oil Automatic Combustion Controller Setting & Parameters Status.SIPART-24 Setting Setting Exisisting setting changed by ADDRESS Recommend Remark values In boiler ship staff on ed by Aalborg 28.02.07 PL 04 0.20 0..22 0.28 Increase to 0.28 to cop up with PL09 value 0.28 PL 09 0.24 0.23 0.28 CCN1 cp 0.12 0.1360 0.20 at .136 value fuel not picking up even after Found Ok PL 09 set for 0.26 or 0.28.So set cp = 0..2 CCN1 tn 4.50 3.00 3.00 CCN2 Cp 0.135 0.15 0.20 Kept on 0.2 to cop up with PL 09- 0.28. CCN2 tn 3.50 4.50 3.50 Letter Template ANALYSING THE CHANGES MADE 1. Changes made on the Oil Flow control valve and the parameters CCN1 cp & tn will make the operation of the Oil Flow control valve quicker. - REPLY - YES 2. Increasing the setting of PL 09 from 0.23 to 0.28 will increase the Oil Flow setting at the time of ignition. -YES LET US LOOK AT THE PROBLEM IN A DIFFERENT WAY:-

SIPART 4 ~ 20 mA DR 24 K

C I/P Converter A B D E E F

FLOW METER R E N R U B

N BY-PASS VALVE I A M

FUEL OIL COMPRESSED AIR

ELECTRICAL SIGNAL

THE CONTROL LOOP As, we are all aware, the Oil / air controller SIPART DR 24 sends a signal via I/P converter to the Oil Flow Control Valve. The Flow meter then measures the actual oil flow and sends a feedback to the controller. The controller must compare the required oil flow value to the actual oil flow value and then, send signals accordingly to the Oil Flow Control Valve. During starting of the Aux. Boiler, the fuel control loop is maintaining the Recirculation flow. For the sequence to proceed after completion of purging, the air and oil flow must come to ignition position values ( i.e. PL 09 – for oil & PL 04 – for air ). In our case, since the pilot burner is getting inserted and firing, means the air and oil flow values are satisfactorily reaching ignition position value. WITH PREVIOUS SETTINGS PL - 09 = 0.23 = 23% At the time of ignition, the Oil Flow Control valve is opening enough, so that the actual oil flow measured by the flow meter is 23%. That is why the sequence was proceeding to next step i.e. pilot burner firing. Further, the Recirculation valve and Fuel Oil shut-off valve were operating at the right time. Letter Template As I understand from you letters, after the Recirculation valve and Fuel Oil shut-off valve were operating, the feedback from the flow meter still showed around 23%--- . Pl Ref : the Reply -1 AT THIS POINT I HAVE TWO QUESTIONS The Oil flow of 23% should immediately press up the short line upto the main burner.The settings of Oil Flow Control Valve and parameters - CCN1 cp & tn make the valve quicker. But then what significance do they have in our case? In earlier condition too, we could get the oil flow ( as measured by the flow meter ) at ignition time i.e. 23% without any problem. Pl Ref : REPLY– 2 . WHAT I AM TRYING TO GET AT IS,

23 % 15 ~ 17 % R E

N FLOW METER R K U C B A

B N

I E A G M A K A E L

1 .If the recirculation valve is leaking, 23% is flowing through the flow meter but some oil is returning back via the recirculation valve to the mixing column. only 15 ~ 17 % is reaching the main burner due to which nozzle pressure is not building up fast enough. This could explain, that, opening the bypass valve would increase the oil % to the main burner and nozzle pressure would build up faster. At present, the same condition is been achieved by increasing the oil flow at ignition PL- 09 to 0.28 = 28%. If there is a manual valve on the recirculation line, this can be checked. Pl Ref : REPLY – 3 2 . Calibration of the Flow meter is not correct. Let us consider the flow meter is showing 23% but the actual flow is only 15 ~ 17 %. I am aware that the mechanical part of the flow meter was found normal. Also the pick up and magnets on the screw shaft were found normal. The frequency feed back signal from the Flow meter reaches the F/F & F/I converter. If the calibration of the converter is not correct, the indication will show 23% to the Controller but the actual flow could be much less. Here again, opening of by-pass valve or increasing PL 09 to 28% will ensure enough oil to the main burner to fire. The best way to confirm this would be to make a record of various readings at different loads – LOAD ACTUAL OIL FLOW OIL FLOW METER in AIR SIGNAL NOZZLE BOILER FO INDICATION ON THE lts/hr (this is from the OUTPUT - I/P PRESSURE PUMP CONTROLLER (this is F/F converter) CONVERTER PRESSURE from the F/I converter)

We can request sister vessel to send in the same readings and then we can compare. Pl Ref : REPLY 4 .3. Finally the Main burner inner & outer tubes having some defect, wrong supply nozzle ( as advised by Aalborg) having more holes, bigger diameter etc could lead to delay in nozzle pressure build up. We can rule out a choking after the recirculation valve to the main burner. This would also bring about a delay in nozzle pressure build up. But then actual flow through the flow meter will also fall once the Recirculation valve and Fuel Oil shut-off valve operate. Indication will show lower value and controller will try to increase flow by opening Letter Template the Oil Flow Control valve more. Reddish - Golden flame and dripping of the main burner are best explained by point 3. Let us see how things work out once the ordered nozzle is received. I am curious, want nozzle is being used on the sister vessel. Maybe the complete Main Burner lance on-board is defective. As per your last message - Present Observation 1)Now Boiler automatic firing is improved. No misfiring in last 24 hours. 2)Flame is light reddish & coming down just above 1.0 -1.5 meter of the furnace floor. After firing on auto at minimum ignition position 28% Load, the load is smoothly establishing to 17%-18%. But at this Load Air flow is hunting between 16% -19%. It is more than before. But after changing over Load to manual at 22%-23%, Air flow hunting is reduced. Hence Load is kept in Manual. So Please advise? PL Ref REPLY – 5 Please note, if the problem is one of the above (especially point 1 or 2), at 17 – 18% load the actual oil flow reaching the main burner would be very less. This would cause an unstable flame. Increasing the load to 22 – 23% would improve condition. Fluctuation of 2 – 3% in air flow is not too much. Depending on the FUP curve, say 10% reading is 11% actual and 20% reading is 19% actual, you will find 3% reading variation is lesser actual fluctuation. Whao!! That’s a real long letter. Hope it is of some use. Please revert at the earliest if something is not clear / correct . Also if you find something. Awaiting your reply. Thanks & Best Regards, Suri. ===Reply for the above mail date -15.04.07, Singapore . ======- Dear Suri Sab, Thanks for the long mail .Please find the reply. Kindly acknowledge the receipt of the Second E-mail with attachments regarding the case study. Attaching copy of the mail form Aalborg, replying to vessel reporting .

Query 1 & 2 After Recirculation & Fuel Oil shut-off valve operating, feedback from flow meter still around 23%. What significance in our case? In earlier condition too, the oil flow transmitter at ignition time - 23% Reply -1 & 2 Negative- The feedback from the flow meter was dropping form 23%.- to 12-13% momentarily. This 12--13 % drop was persisting for about 10 sec.(mean 60% of the safety time). Hence nozzle pressure was not building causing an unsuccessful flame transfer. So worked on the response time of flow regulator & IP converter sensitivity by adjusting Cp, tn, & Cv values. Now flow controller response faster in time.

Reply 3 - Not leaking. That possibility was ruled out by manual valve on recirculation line. Reply 4 – Flow meter & Transmitter unit , Repair Kit / Bearings are ordered and waiting for delivery to rule out this possibility. F/F & F/I converter calibration not yet done. Shall attempt after replacing recommended Burner nozzle by Aalborg & Flow meter / Transmitter unit , bearing etc. May have to change the response time values after the above changes.. Reply 5 CNN2 tn, we have tried to increases to 4 to bring closer to Aalborg recommended values 4.50. Noticed that boiler was not accepting this proposal at this scenerio, with tendency for increasing hunting in auto. Hence this value revert back to 3.5 to old values where the boiler was found operating comfortably.

Conclusion – In view of On board limitations like vessel schedule, its priority jobs, lack of required spares in time, (ex: Boiler burner nozzle, flow transmitter, suspected bearing,) Lack of all relevant information in time, are the part of a gap between the lip and the cup, to pin point to nail down exact roots at this point of time. But at this scenario, so all in all, it's a question of borrow here and lend there to make it all come up into a greater final making of a smooth boiler operation without misfiring, causing the sun to shine a little bit brighter for Engineers.

Trust all in good order. Thanking you with Best Regards,

George John.K, Chief Engineer M.T.Kingfisher.