Diesel engine can not give more than half load 10

[ViCH]

Hi everyone. I am electrical technician, and I have problem with Emergency Diesel Generators at site. Full Power Capacity is 2.7MW, but we get speed unstable starting from 1.3 MW, if we want to give more power then engine looks like can not accelerate and frequency start to drop until under-frequency trip. We already check all fuel injection pumps, fuel pressures condition of valves, fuel filters.. Check electronic controls and all auxiliaries, but did not find any major problems.
By trending I found fuel demand is adequately changes with load requested. But I also mentioned that manifold air pressure is maintain 14.2 PSI before start, and 14 PSI +-0.3 fluctuating during and after start. Is it OK? Could it be problem with turbocharger, or wastegate control?
Engine: GE 16V228.
Turbocharger: 7S1716 compressor end. E-40811A

Viktor
Electrical Technician II

 

[miningman]

How many hours on this engine ??? Regardless of DP readings , 1000 hours on air filters seema excessive to me. The carbon in the intake looks really ugly to me and will definitely need trouble shooting by an experienced diesel mechanic........this cant be done on the interweb. How many hours since a complete top end overhaul??

 

[TugboatEng]

It really depends on the filter. We're stretching our Donaldson Power Core filters to 8000 hours and they're still showing hardly any restriction. With closed crankcase ventilation filter clogging is most a thing of the past.

 

[ViCH]

minigsman, I won't protest. You are right. Management aware about problem, and service contractors already come and try to solve issue, by doing overhaul, etc. As I told before, quality of troubleshooting procedures of that contractor was not good. Now management agree to call other guys, but due to virus situation, our borders closed, who knows until when... Engine runtime 7000hrs. Last overhaul - NEVER. I cannt call all activities for that engine as overhaul. It was just partial maintenance/rectification activities. Filters really good, I remove cartridges and check - its clean like a new. Dp during test run is 26 mm(0.04 PSI).

Tugboat, root cause of injector and rocker arm damaged was bad tappet clearance, as contractors said. For fuel we have 2 stages filters, one is fuel/water separator, another high efficiency diesel filter. Pressure after last filter is 7 bar. Dp almost zero.

Today we done test run, and found no any PSI at intercooler inlet, even during acceleration start up. Manifold air pressure maintain vacuum pressure about -0.2 PSI by pressure transmitter. Analog gauge shows zero. sometimes trying to go negative. Exhaust outlet gauge shows same like MAP.. Looks like without load test I cannt do more... This days I want to present to management all findings and request to do load test during weekends. Hope, they approve it.



Viktor
Electrical Technician II

 

[TugboatEng]

I find engines in this power need to see around 50% load before the turbocharger starts to significantly increase manifold pressure.

 

[ViCH]

Hmmmm... Then maybe this is the issue? Once we achieve load, where turbocharger accelerates, it starts playing with fuel?
BTW, today I found in governor settings, that its no any fuel/air ratio calibration gain steps.. Dynamic is constant in setup. So it looks for me, if we will achieve stable work on high load, we loose stability on low loads.. Am I right?

Viktor
Electrical Technician II

 

[catserveng]

Can you save the setpoint file and post it? The limiters are in a different menu than the dynamics in that governor, also there may be fixed limiters in the firmware, since this is a custom firmware for GE, right?

At 7000 hrs a medium speed engine that size is hardly getting broken in, but I would say it has been abused. No/light load operation of these engines will always cause problems, at least from what I've seen and I've worked on a lot of these sized engines over the years.

You only took a picture of the inlet manifold with the debris on one side, what did the other side look like? If the carbon debris is only on one side then it could be due to a leaking inlet valve, especially if you've had issues with valve lash adjustment in the past. If the debris is present on both sides, then it is a problem cause by something common to both banks.

So to confirm, you run a weekly no load test. Then for a couple weeks each year you run the plant off the engine during plant low load periods and at most only see 40-45% load, right?

What about other instrumentation? Does the engine have exhaust port pyrometers for each cylinder? Are the cylinder heads fitted with Kiene valves? If so, do you have a Kiene test indicator?

So above you said "service contractors" came in and did an "overhaul", but then you said no overhaul was done, so do you know what got done exactly? And when the contractor was there, were you able to run the unit under load so it could be diagnosed?

I know your the "electrical guy" but I think you need to not worry so much about the governor, as long as the original setting are in it from startup and commissioning and it performed properly then, then the governor is likely NOT the problem. Now if that is not the case then I would hope someone documented the final startup settings and you should be able to put those in and try again. That family of governor is very robust, and the settings don't "drift" like an older style analog governor. You could have an ECM issue, but that requires a service tool, usually a laptop and the software, and someone who is familiar with troubleshooting them.

Hope that helps, MikeL.

 

[catserveng]

I think I provided you this info in your other thread, but see if your management will let you contact these guys,

https://www.marinsa.com/marinsa-technical-services

They have a good reputation in the marine market and have worked with them on some gensets in the past. I think you're pretty much past finding a free solution for this problem.

MikeL.

 

[TugboatEng]

Starting and stopping this engine weekly is doing more harm than good. The only reason for frequent starts would be to verify starting batteries are in good condition which these engines don't have. You'd do yourself a favor running only a monthly test which is standard for us in the marine industry.


4-stroke turbocharged engines typically have manifold pressure based fuel injection volume limits. In our experience with turbocharger failures the engine operates normally up to about 50% power and then does not accelerate beyond that. Right at about 50% power is when the turbochargers start making measurable boost pressure. Without that pressure, the engine control will not allow additional fuel. This is all below the smoke limit so there is no smoke from the engine despite the failure.

 

[ViCH]

Contractors did:
- replace injectors
- adjust tappet clearence
- replace/clean all filters
- clean turbocharger (I did not see that, and I dont believe that, because turbocharger bolts still have native paint. Maybe they just clean impellers of compressor, who knows)
- replace lube oil
- replace faulty cylinder head
- clean crancase oil catcher

They did not do:
- did not clean intercooler
- did not inspect piston rings
- did not inspect high-pressure fuel pumps

Regarding cylinder testpoints- it has valves for pop-up test, it has thermistors on exhaust side(all thermistor collected in one socket on the top of engine,but not connected to anywhere). Nothing more on cylinders, as I know.

Manifold same on both sides.

Settings of governor was tuned up by vendor in 2011, during comissioning stage, using load banks. After that nobody change that settings.

I will try to share Woodward settings tomorrow.

Viktor
Electrical Technician II

 

[ViCH]

TugboatEng, thanks for advice, I will share it to my bosses. Monthly testrun will be not approved, due to our shift 14/14, but maybe one time per two weeks would acceptable.

Viktor
Electrical Technician II

 

[TugboatEng]

I don't think thermistors are correct, they're probably type K thermocouples in the exhaust ports, maybe type J. Look at the wire color if you can. If you run the engine at a constant load for a while you can use a multimeter to probe each thermocouple. It doesn't really matter what the reading is but you see a lot of deviation that would indicate problems with individual cylinders as opposed to turbocharger/intercooler problems that would affect the entire engine.

 

[gruntguru]

I am waiting with baited breath for the resolution to this problem. It is almost as if the turbine and compressor have become disconnected.

je suis charlie

 

[malbeare]

does this engine have exhaust recirculation or ERG?

A tidy mind not intelligent as it ignors the random opportunities of total chaos. Thats my excuse anyway
Malbeare

http://www.sixstroke.com

 

[ViCH]

well, today I have done sharing session on engine problems to mechanical engineer. He promise to check turbocharger, and fuel line, regarding testruns - weekly based testrun is our technical standard, so he allow to decrease time of engine running, but not the frequency of schedule. Due to closed borders, nobody will call any contractors now..
I already hope, that they will found something abnormal in turbo exhaust, and this story finish.
And no, we do not have ERG, our exhaust is only accelerating turbine of turbocharger and go outside, through silencer to exhaust outlet pipe

Viktor
Electrical Technician II

 

[ViCH]

Here are our air system P&ID drawing and hardware block diagram for reference.

Viktor
Electrical Technician II

 

[ViCH]

Catserveng, here are zipped files with tags and configuration for woodward governor. Please check, maybe You will notice sth abnormal. Openable by notepad.

Viktor
Electrical Technician II

 

[ViCH]

Turboateng, yes You are right, it is thermocouples, not thermistors. I just wrongly named it. K type.

Viktor
Electrical Technician II

 

[catserveng]

Here is Word Doc of your configuration,

https://files.engineering.com/getfi...b24-a647-3163cc3c9c98&file=GE_723_Config.docx

(for some reason the insert link for attachments was not working for me today)

If you look at Service Menu J, Limiters (page 8), you see you have no access to settings .04 (Torque Limit) and .05 (Smoke Limit) because your firmware has an "Opacity Map" with three selections, these were mapped fuel rate to MAP limit maps developed by GE to limit exhaust smoke per IMO and some other regulatory guidelines, you can't change them you only select one of the three, with the 20% map being the "cleanest" and the 30% map allowing more fuel for a given MAP. If you change the parameters from 1 to 3 you may see a slight difference in the engines performance.

On same page is the Analog Input scaling, the scaling is set for 4mA=0PSIA and 20mA=75PSIA, because the MAP sensor is critical to the proper operation of the limiter map, you should verify for proper operation, when check its calibration make sure you do a 5 point check and check linearity and hysteresis, since the standard sensors used by GE and Woodward over time could have issues with both.

As we discussed before, this is a custom control with a lot going on inside of it, one of the ports is configured RS232 for communicating to the engine ECM and the I/O modules, the other port is configured for Modbus, not sure if you're using it but it will have a ton of info on it if you are inclined to use it.

The link I sent you for Marinsa talks about their remote technical support, I know several engineers in the marine community who have used them with good results (just not cheap)so unless they have closed off your phone and internet, you do have access to one of the best sources of technical info on these engines I know of. I have no commercial interest in that company, so you may want to consider having your boss open his wallet and start a dialog with a competent technical resource on that engine family.

MikeL.

 

[ViCH]

MAP sensor we checked, its working well on different pressures. Do you think 5 point is must, if this two configure lines shows:

CONFIGURE: Z10: CFIG OPTION.USE 5-GAIN MAP 0
CONFIGURE: Z10: CFIG OPTION.USE CONST DYNAMICS 1

BTW, today we did no-load testrun with open port of turbocharger inlet, and we monitored performance of compressor visually. It rotated very fast, and accelerated well immediately after engine speed achieved setpoint. No any abnormal sound from turbocharger observed, no DP on intercooler. So, it looks like turbocharger projected to maintain atmospheric pressure in manifold intakes all the time. Or at least until 50% of load, not sure.

Regarding Opacity MAP - thanks for explanation, actually I was ready to ask You about this configuration. Maybe it is a point.

Regarding Marinsa - thanks for proposal Mikel, I will suggest it to my bosses, but only after borders will be open. Now nobody wants to do any claiming for contractor calls. Coronavirus heats not only human, now our equipment also involved
Offline support will be difficult to approve, but at least I will try.

Viktor
Electrical Technician II

 

[catserveng]

The two parameters you are asking about are for your governing dynamics, not your fuel limiter mapping.

No you don't have to do a 5 point verification on the MAP sensor, but it will be a guess as to if it is working the way it should. Why not do it right and know for sure the MAP sensor is doing what it is supposed too? In the firmware configuration your MAP sensor is very important.

In doing performance testing with the 723's and engines using either multi point fuel limit maps, opacity maps or air/fuel ratio maps that a supposedly "good" MAP sensor would cause all kinds of grief. So as a habit whenever I deal with one a do a pretty complete check of them, and in some cases get rid of the cheaper automotive type sensor and go to a more robust (and adjustable) industrial type sensor. This may or may not be part of the problem, but should be an easy box to check off and know for sure.

I still think based on all the info so far you have a mechanical problem, and continuing to test and evaluate at no load is likely not going to get you anywhere except waste fuel and time. My 2.5 cents worth.

MikeL