Alfa Laval S846 HFO Separator problem

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Namit4
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Re: Alfa Laval S846 HFO Separator problem

Post by Namit4 »

Namit4 wrote: Wed Aug 31, 2022 3:05 pm Facing some issues s586 hfo purifier,low pt4 alarm , purifier cleaned with all new orings,no problems in discharging also.But its pt4 pressure keeps on fluctuating very fast from 0.5 to 1 bar aprox.its not stable which leads to low pt4 alarm after 2 -3hrs . Pt4 is 1.5bar , temperature 95 to 98. Oil density is 0.9748.
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Re: Alfa Laval S846 HFO Separator problem

Post by Namit4 »

Facing some issues s586 hfo purifier,low pt4 alarm , purifier cleaned with all new orings,no problems in discharging also.But its pt4 pressure keeps on fluctuating very fast from 0.5 to 1 bar aprox.its not stable which leads to low pt4 alarm after 2 -3hrs . Pt4 is 1.5bar , temperature 95 to 98. Oil density is 0.9748.
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Re: Alfa Laval S846 HFO Separator problem

Post by Namit4 »

Always getting pt4 low pressure alarm when comes discharge time ,just few mins before alrm coming low pt4.Have cleaned bowl, water block is ok no leak sv10, sv15 working fine.
Fuel density is 0.9744.
Many days has passed trying to rectify but no success.Please help with any suggestions.
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Re: Alfa Laval S846 HFO Separator problem

Post by Atlantic »

Hi,

Is the pt 4 the pressure from the feed pump? If so check your suction strainer make sure the feed/booster pump is giving the right pressure all all valves set right? Problems with the pump maybe dirty pressure regulating valve or worn pump?

Please let us know if you find the issue.

Regards
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Re: Alfa Laval S846 HFO Separator problem

Post by Namit4 »

No the pt4 is back pressure and pt1 is inlet pressure.Pump outlet is ok idle is 0.58 bar and while purification its 0.25 bar (pt1). And pt4 is 1.9 to 2.0.
Pump filter is cleaned daily basis.But alrms low back pressure pt4 low coming before disharging.All water valves are ok .
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Re: Alfa Laval S846 HFO Separator problem

Post by popeye62 »

Hello Namit. Is the back pressure fluctuating all the time between discharges? Is the time between discharge 60 minutes? It is the clean oil outlet paring disc that discharges the clean oil and the back pressure is due to the resistance. Is the discharge valve full open or are you gagging the valve to produce the required back pressure of 1.9 - 2.0b? The fluctuating looks like air being drawn in to the suction side of the pump but your settling tank is above the pump so should have a constant head of pressure (is the settling tk valve fully open?) Is the filter lid drawing in air? If you open or close the manual discharge valve to adjust the BP, does the fluctuating stop? When you say that the alarm comes before discharge what do you mean? How close to discharge, what point in the programme? e.g. displacement water open, feed valve on re-circ? Have you tried reducing/increasing the throughput? Set it to 110% of engine consumption. It is quite a light HFO but shouldn't be a problem and the temperature is good. Is there any water in the fuel?
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Re: Alfa Laval S846 HFO Separator problem

Post by FedeZardo »

Good day gents, I'm having problems with my separator on PT5( water outlet ), when start the separator, for a few hours is working without problems , after that, start to lose the pressure on PT5 until came on alarm 0,2 bar .
I have the same problem on 2 separators working on the same engine room , already check the drain valves, the supply water pressure , air pressure , overhaul the water block , check paring tube o-ring, paring tube spring is moving freely.
The manual says for low pt5 to move inwards the paring tube, already try that also but without results.
Any suggestions about this issue ?
Thanks!
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Re: Alfa Laval S846 HFO Separator problem

Post by popeye62 »

Hello FedeZardo. I am presuming this is set up as ALCAP and the water sensor (MT50 or 60) is working and controlling the water discharge valve V5. During the few hours when everything is working without problems what is the pressure on PT5? Is it the same pressure as PT4? During a stable separation period what happens if you open the displacement water, does the pressure on PT5 change and does V5 open? Could V5 be passing? Can you disconnect the pipe from the valve to the sludge tank and see what's coming out? Is it possible the movement of the paring tube is being restricted over time by heat? Are the height measurements correct as per the manual? Have you adjusted the paring tube adjusting screw using the nomogram in the manual for the density? If nothing comes out of V5 when you adjust the paring tube either fully in or out it seems like there is nothing in the water paring chamber which is unlikely. Is the throughput correct, the volume of oil going in? try increasing it. Is the sludge tank filling more quickly?
Having said all that I cannot understand why it would affect two separators when you have checked common supply systems of air and water etc. unless the volume is low i.e. if you shut down one will the other run without problems? Is it possible there is a high back pressure in a common sludge tank? Good luck. John
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Re: Alfa Laval S846 HFO Separator problem

Post by FedeZardo »

Hello John! thank you for your answer, if I open displacement water the pressure for PT5 keeps steady around 1.6 bar and would pass water to the sludge tank.
I checked the drain valve but there is no leak from there , PT1 pressure is 0.20 to 0.22 bar and the separator is working with MGO, we are not using heat.
I'm starting to think that could be high back pressure in the sludge tank because is common for both of them.
But the problem was already there when only separator 1 was running.
Separator 2 now is running OK without problems after the overhaul of the water block.
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Re: Alfa Laval S846 HFO Separator problem

Post by FedeZardo »

Hello again! Now the problem start to show up on another separator on different engine room, the model is S836 , this separator has been running for more than 2 weeks without problems, is a coincidence that also in this one is starting the same problem .
The water supply and air supply for this one is separated for 1&2(PT5 low problems) did someone experience this kind of problems before ?
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Re: Alfa Laval S846 HFO Separator problem

Post by popeye62 »

I'm not convinced about high bp in the sludge tank and now the problem is on another which is a separate sludge tank. Everything else has been checked: speed, the parameter settings etc? Is there a lot of water in the gas oil? Can you try disabling V5 and its alarms (the water, if any, would still be picked up by the sensor but ejected through the bowl instead of going through five opening cycles of V5)? I cannot see how the water block would have any effect even if it didn't admit conditioning water into the bowl as any water in the fuel would start to fill the bowl and consequently the water paring chamber, but the bowl is closing and staying closed I presume. Is the quality of the disp./operating water good? Has anything changed prior to these problems? Was it an issue that you inherited? Have you had a blackout that could have fritzed a setting? Check all the parameter settings are the same on the three gas oil separators. Any issues with the LO separators? Has the fuel changed? I'm grasping a bit here.
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Re: Alfa Laval S846 HFO Separator problem

Post by FedeZardo »

I'm sorry for the late reply, I have one separator on each engine room back to service after I replaced all the flow regulating valves 1.6 for v10 / 11 L/M sv15 and 2.8LM for sv16 . This actually solved the problem of low PT5 on all separators.
I'm impressed to be honest that I had the same issue on all separators at the same time.
Could be low PT 5 also if there is no water on the separated fuel ? Actually conditioning water is open every 5 mins on the separator when running.
Best regards, Fred!
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Re: Alfa Laval S846 HFO Separator problem

Post by popeye62 »

Thanks for the reply, Fred and well done. I admit that I cannot understand why changing the valves on the water block would solve the problem but I will take it. If there are any more problems, a quick fix according to the manual for 'Pressure in water outlet PT5 - LOW' is 'Force the paring tube inwards or increase limit (Pr13)' Process parameter 13 is factory set at 0.2b with an adjustable range of 0.0 - 6.0b. To 'increase' is counter intuitive to me but I would try it either way if needs be. Is Installation parameter 4 (In4) set to the correct machine S846 or whatever the machine is as this does have a bearing on quantities of water added to the bowl? I see the minimum op./cond. water pressure is 1.5b and there is no alarm for this so it could cause problems elsewhere but if you have the flow, which may have been rectified by changing the water block valves, it shouldn't be an issue. If the problem comes back I would check the actual flows with a calibrated bucket and a stopwatch.
I think the 'conditioning water open every 5 minutes' is actually the closing water pulse, Factory Set Parameter 41 (Fa41) which is set at 5 minutes and opens the closing water valve for 1 second. If conditioning water was added during separation it would act like displacement water.
I don't believe that a lack of water in the fuel would cause a low PT5, any liquid at the bowl periphery would travel up the outside of the top disc/under the bowl hood into the water paring chamber. If it is oil it is no problem because V5 is closed until the water builds up to the extent where it passes out with the clean oil and is picked up by MT50 which then triggers V5.
Where is your op/cond water coming from; a main or a header tank? What is the pressure in the main? Is there an in-line filter/strainer?
John
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Re: Alfa Laval S846 HFO Separator problem

Post by FedeZardo »

Hi John ! So, basically the problem still there, the water source are from technical water tanks , we have separate system for aft and fwd engine room. The filters for the blocks are check and clean. Also I have 4 lube oil separators running and without problems, this problem is just affecting hfo separators.
I double check on the manual regarding the water flow for this separator 8636 and the flow regulating valves are correct.
What I noticed now is that, once the separator is running is keeping a good PT5 pressure, around 2.8 to 3.3 bar .
After a discharge occurs(every 2 hours) this pressure is not increasing and PT5 is coming to alarm at 0.
Today I went through all settings and everything is under factory set points.
Thank you for the correction, the pulse is for conditioning water.
I still can't understand why this separators start with this issues and why the alarm is so random. Could be working for one day without problems and suddenly after discharge the problem is back .
Thank you for all your advices Jhon !
Regards fred!
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Re: Alfa Laval S846 HFO Separator problem

Post by popeye62 »

Hello Fred
So it does work from starting and will run all day, discharging every two hours but will the randomly fail to come back on separation after a discharge, is that correct? After it has failed will it come back on or do you have to stop it (complete shutdown) and restart it? The same thing happens with the other separator? Is the failure at the same time as something else e.g. filling the settling tank? or the level of water in the tech. water tank? When did this issue first start, have the separators been overhauled?
The only thing that is common to the fore and aft separators is the fuel, has this changed recently? Has your amount of sludge production changed?
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