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Diesel engine can not give more than half load
10

Diesel engine can not give more than half load

Diesel engine can not give more than half load

(OP)
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

RE: Diesel engine can not give more than half load

have you checked the air cleaner ?

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

RE: Diesel engine can not give more than half load

(OP)
U mean air filter? Yes, we have DP gauge which shows good reading, and DP safety switch, which is also healthy. Filters was replaced approximately 1000 run hours ago.

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

Clearly, without turbo boosting pressure, the engine cannot produce full power.

RE: Diesel engine can not give more than half load

(OP)
Also think so. But as I am not mechanical, I need to know, how turbocharger maintain air pressure in intake air manifold? What values should be? Any experiences? I have two theory:
1) Air pressure not raising - problem.
2) Air pressure maintain even with high vacuum on exhaust - no problem.

Due to no experience, I am in doubt...

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

It looks like your manifold air pressure is absolute (not relative to atmospheric) as it's ~ atmospheric when the the engine is stopped. The turbo should be building boost as the load comes up, probably in the 30 to 45 PSI range. Most diesels don't have a wastegate but it sounds like yours does. It's possible the wastegate is stuck open, letting most of the exhaust gases to bypass the turbine. Without the exhaust going through the turbine, the compressor is unable to create the boost you need to make full power.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Diesel engine can not give more than half load

(OP)
Thanks for reference bro! 30-45 PSI is your own experience? How big engine it was?
Regarding waste gate - very probably, thanks for idea. What about turbocharger itself? Could it simply stack? Or if it stack, I can not get any load at all?

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

The turbocharger being seized is highly unlikely- if there was a lubrication failure or some other issue, turbos will typically rapidly destroy themselves and send parts downstream, destroying more things, before they will seize.

RE: Diesel engine can not give more than half load

(OP)

Quote (dgallup)


Most diesels don't have a wastegate but it sounds like yours does.
Well.. Looks like You are right, this engine also do not have waste gate. I thought that light gray solenoid upstair is a valve for waste gate, but it is not. This valve is just for vacuum ventilation after crankcase coalescer.

SwinnyGG, then why intake manifold pressure not raising? Any ideas?

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

Still seems like a stuck turbocharger. Perhaps the last time it was shut down there was a lubrication failure and the bearings are damaged. That would put a lot of backpressure upstream in the exhaust.
Is there no RPM indicator for the turbocharger?

RE: Diesel engine can not give more than half load

(OP)
no, no any... Only speed sensors for main wheel and crankshaft..
I did not notice any backpressure on exhaust, at least still can see smoke from muffler.
Looks like we have to dismantle turbocharger to check it. What if we try to disconnect income pipe to turbo compressor? Should compressor vanes rotate freely by hand if bearings is normal?

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

For the turbo, yes, you should be able to move the shaft/wheel assembly easily by hand. You should also check radial and axial endplay if you suspect the turbo is a problem, the procedure should be in your service manual.

Can you verify the manifold pressure with another gauge? You may have an air manifold pressure sensor fault and the ECM may have a limiter map to prevent overfueling if the manifold pressure is not high enough. On some of these engines the air pressure fuel limit map was in the ECM, on others it was in the Woodward governor.

Also, where in the intake air system is the air manifold pressure sensor, before or after the aftercooler (intercooler in some engines)?

A medium speed engine that size and rating will likely see the inlet manifold pressure drop to a vacuum at very low speed and load, how much depends on the restriction of the aftercooler core, as speed/load comes up the turbo will start to develop boost pressure and the manifold pressure will increase.

If this engine has been lightly loaded a lot, you may have a plugged aftercooler core. If you're seeing boost pressure (air pressure out of the turbo compressor going into the aftercooler) but manifold pressure is not increasing, you'll need to inspect the air side of the aftercooler core.

I'd suggest you get two good pressure gauges, install one on the outlet of the turbo compressor before the aftercooler core, on that engine a range of 0-60 PSIG should be ok. On the air inlet manifold side you'll need either a vacuum/pressure gauge or an absolute pressure gauge to get an accurate reading, on the pressure side should go to about 60 PSIG.

On the aftercooler core you should see a pressure drop at load speed/load of less than 1 PSIG, at full load max pressure drop on a core that size is about 4 PSIG.

Hope that helps, MikeL.

RE: Diesel engine can not give more than half load

4-stroke diesel engines typically have intake manifold pressure based rack limits.

Is this an electronic governor or mechanical?

If electronic I would suspect a failed turbocharger or intake air pressure sensor.

If mechanical inspect the sensing tube and diaphragm in the governor.

RE: Diesel engine can not give more than half load

(OP)
Thanks guys, for your comments.
Engine is 1000 rpm rated, governor Woodwart 723plus.
And yes, this engine usually runs on low load (0-40%).
Manifold intake pressure sensor located on the end of left manifold, after intercooler. On right side manifold same hole is plugged, i plan to install 4bar gauge there.
Regarding gauge between compressor and intercooler, i have to check, is it any point(hole) for that.

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

(OP)
Well, I have some updates.

1) We achieve to compressor vanes of turbocharger and found it clean and free rotating. No abnormalities.
2) Double check air inlet filters - condition clean.
3) Install pressure gauge (55 PSI) to inlet manifold. Standby reading ZERO.
4) Dismantle pressure sensor from manifold air inlet, and found it is giving 14.5 PSI, like it was calibrated in vacuum. Done blows inside sensor - governor feels changes. So sensor not stack. Install sensor back.

One interesting thing I also found, when I disconnected sensor for Manifold inlet pressure, governor controller shows false signal of MAP, and..... false signal of Waste Gate... Once sensor install back, and reset alarms, both of them gone. I could not find any waste gate locally. If it is absent, why we need it in logic?
Another question, should I re-calibrate MAnifold sensor pressure, to make it show real pressure, or it is normal practice, to show atmospheric pressure (~1 bar) as real zero PSI?

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

Disclaimer: I don't know stationary engines. BUT ... In the automotive world, manifold pressure sensors (MAP) are "absolute" pressure sensors. Key on but engine off, they should read whatever the local barometric pressure is.

By "Standby reading zero" ... What do you mean by "standby"? Engine off, or engine idling, or running at rated speed but no load, or under load?

It is totally normal for turbochargers to not generate much, if any, boost pressure when the engine is not running under load! They're driven by exhaust pressure, and if the engine is not running under load, there's not much exhaust pressure, so therefore not boost pressure. The turbocharger will be spinning (at a relatively low speed), but not really doing anything.

Try to load the engine a bit, and see what your intake manifold pressure gauge does when you do that.

RE: Diesel engine can not give more than half load

(OP)
Standby - I mean engine stop condition. On running without load MAP readings drop a bit (~13.9). Gauge not tested yet, no chance for test run until Wednesday.

I still can not find any waste gate, bypass or throttle valve in air intake system.. Governor do not have any intakes of that. Does it mean all this device absent, or it could be mechanical without any feedback? If absent, then how engine control speed, only by fuel injection? If mechanical, then where I can find it, how it looks like? Refer to photos on topic please.

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

That engine's speed and torque are established through fuel delivery control only. Since stationary engines are normally designed to run under load at a fixed speed, there is no regulation of boost pressure. The turbocharger is free-spinning and you get whatever boost pressure it feels like delivering. The smart people who designed it originally, carefully sized the turbine and compressor so that when the engine is running at rated power, the turbocharger operates at rated speed (and boost pressure). At part load there's less exhaust pressure so the turbo spins slower so it makes less boost naturally. No wastegate control is necessary if the original designers got the design right (provided, of course, something hasn't gone wrong).

Since turbochargers take a finite amount of time to get up to speed, the fuel delivery controls have an upper limit based on whatever the intake manifold pressure is, to avoid producing a big cloud of smoke if someone asks for a step-increase in engine torque/power output without waiting for the turbocharger to spin up and make the needed boost pressure.

HOW it does that, is outside of my knowledge. In automotive applications, the old-school diesel engines had a mechanical governor inside the injection pump. The new stuff uses electronically-actuated injectors and everything is in the ECU calibration.

RE: Diesel engine can not give more than half load

Yes, speed and load are only directly controlled by fuel rate. Certain applications that needed fast transient response had a wastegate option, you don't appear to have a wastegate installed but the 723 firmware could have the programming for it.

This worked before and made rated load, right?

Based on you pictures the MAP sensor is mounted at the rear of the left bank inlet manifold. Based on the info you provided it is an absolute pressure sensor, so if your site is close to sea level that the engine stopped reading you are seeing is correct. The fact it drops slightly into a vacuum with the engine running at no load is also a valid reaction by the absolute pressure MAP sensor. As you add load the pressure should go up, is it?

Based on your pictures looks like a port is available on the right bank inlet manifold to connect a gauge. install a mechanical gauge (vacuum/pressure) there, compare its reading to the MAP sensor readings.

You are able to connect and read data from the Woodward 723, right? You should be able to see parameters for the fuel limiters and see if the MAP sensor is affecting the fuel demand output to the ECM. I'm assuming this is the same unit you did another post on before, right?

MikeL.

RE: Diesel engine can not give more than half load

(OP)
Exactly, same. I did not find any problem on governor and EFI site, and started looking for problem in mechanical site.
Gauge I already installed this night, 4 bar rated.
Problem is, that i can not simply test this engine, due to we are production plant. Every wednesday we have no load test. And we do not have option to do load test, except of power failure situation. So I have to be ready, when it happens :)
I am self learner in all this controller and metering devices, now its time to learn more about mechanical site,
I hope one day engine will surrender...
Regarding running on rated load before - no, we never got this engine run on more than 2MW. But I remember time, when it was stable on 1.6-1.8MW. Now its not stable even on 1.2MW.
Yes, I have laptop with Woodward software. Governor have inputs of MAP, MAT, water and lube oil temperatures and pressures, camshaft position, speed sensors. Output only one - fuel demand to EFI board. During run without load fuel demand is about 45%, and load calculated shows about 1%.
Regarding wastegate- if this engine does not have it, could active alarm and warnings of wastegate make problem to stability? Can I disable it, or it still can be useful in soft logic?

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

If the turbo spins freely by hand you probably have a blockage somewhere. I haven't seen a response to CatServ's suggestion to test the aftercooler -is the pressure before and after the aftercooler the same?

Exhaust system is another area you should check for blockage. A pressure gauge at the turbine outlet should read less than 2 psi under load. The pressure before the turbine should be similar to the intake manifold pressure. Check your manual.

Can you set yourself up to do some testing under load? Connect some high power loads from around the plant? Build a simple load bank (tank of brine with plate electrodes)

je suis charlie

RE: Diesel engine can not give more than half load

(OP)
Nobody will allow me to do load test during plant production. Regarding load bank, - our generator 11kV, hand making load banks is simply not safe. Our engineers was trying to purchase load banks, but due to coronavirus all plans freeze.
Regarding blockage in intercooler. If clean air pass through compressor, how it can be clogged? And how it achieve 40% load, with blockage in I/C?
One more question, what temperatures should be on turbocharger surfaces of such big diesel engines?
Regarding pressures which should be on manifolds, - nothing in my manuals.. In FAT test reports also no any readings on that.

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

Intercoolers have fins that make very small air passages. Couple that with 400°F+ air leaving the turbochargers, oil mist, and dirt from the air and you have a recipe for clogged intercoolers. High efficiency air filters will prevent this.

RE: Diesel engine can not give more than half load

So you've provided a good piece of info, so at some point earlier in the unit's life it made 2MW, then it would still carry load up to 1.6-1.8MW, now as time goes on you have problems at lower loads. In between this you run the unit at no load. This type of problem is not typical for a controller related issue. This type of worsening condition is usually mechanical in nature

I think you need to stop worrying about the "wastegate", engine and controls are still configured they way they were when the engine would make 2MW, right? If it was a problem it would have been there from early on.

As for the turbo and aftercooler, running a large turbo (actually any turbo) for extended periods at no load can result in oil leakage past the compressor and turbine seals, causing oil vapor to migrate to the exhaust and air inlet systems. You have large aftercooler cores on each side of the engine, as oil film builds up on the air side surfaces, it captures and holds all the small fine particles that got past the air cleaners, adding restriction. It doesn't take a completely plugged aftercooler core to start making your engine not perform, a partially restricted core will reduce air flow at higher loads, the more it restricts the less load you will be able to make. I'm not saying this is the only possible problem, but based on what info you have provided so far I'd say it needs to be checked.

The fact you cannot test the engine with load is probably the root cause of your problem. I have just been thru a similar issue at a government run medical facility, they have not been properly load testing their 2.5MW emergency generator because of cost, so mostly they run just start tests and for the last few years do a site load test once a year, but each year they were not able to carry as much load as the year before, so got to a point where the unit wouldn't carry more than 1MW. Everyone started pointing fingers, guy in charge of maintenance retired just before this got really serious and seems for the last few years has been getting a bonus for saving money on maintenance. After a bunch of finger pointing and repairs done that didn't go anywhere, I was asked to help evaluate the unit. We got a load bank on site, found a number of minor issue but two main factors for the continuing loss of power output was partially plugged intercooler core (what the manufacturer of that engine called it) and the critical grade exhaust silencer badly plugged and internally collapsed. Then unit ran fine up to about 800kW during our initial test, then started to surge, found the intercooler restriction was at 7 PSIG and the exhaust backpressure reading broke the digital manometer, a pressure gauge was installed and we had 8PSIG of backpressure on a unit designed for a MAX backpressure of 25 inches of water.

In you case I think two things need to happen, you need a way to properly test with a known controllable load like a load bank or run loads in your facility in a way that you can control the loads, and yes, that means production will be affected. Next someone who has a proper level of expertise needs to troubleshoot the problem in a methodical manner with the right diagnostic equipment and information about expected parameters and tolerances from the engine manufacturer.

So far you seem to have struggled getting thru what you could on this problem, fully understand you may not have the expertise you need to get to the bottom of this, but you have certainly done a good job with what you have to work with getting this far, now time for the equipment owners to pony up and get it fixed right, and in the process let you hang around and get some training and troubleshooting experience.

Hope that helps, MikeL

RE: Diesel engine can not give more than half load

(OP)
Well, thanks for good words and advices, and sharing of your experience. Now I get point with intercooler. I think, if its partially clogged, I still may catch up higher pressure between compressor output and intercooler, compair to manifold MAP. Plug is there, gauge I will find.
Regarding owners and authorised troubleshooters, its very complicated issue. OEM vendor of this package is Intergen, Italy. As I understand, my company already do not have contract with them, and all service and repair support making by contractors from asian contries. This guys are not belong to GE or any known famous diesel engine manufactures, and even they have a lot of experiences, their logic of troubleshooting make me crazy.
Once, during turnaround activities night shift found some diesel leak from one of cylinder head. Engine was still running without alarm, and leak extingush itself. But after several hours our lube oil level start increasing. Coolant level maintain. After discussion with bosses, we stop engine with clear understanding that fuel found pass to lube oil. Service team was available in camps (they come to do some service on cylinder valves and injectors), so we call them. First what they said- fuel do not have any pass to lube oil, and ignore info about diesel temporary leak.
You will also become crazy, when know what they did:
1) They said our lube oil bad condition, its foaming and thats why level raising.
2) They drain lube oil
3) They top up new lube oil
4) They run engine.

Of course, lube oil increase again. They stop engine, and said that maybe its lube oil filter, or heat exchanger problem. When I ask, how can be 80% of lube oil become 100% due to dirty filter, they said "old oil could not drain".. They check and clean filter. It was dirty a little. Then they ask to open PTW to service heat exchanger. At that moment I exploded on them, and call my bosses. He ask them to check cylinder which was leak.. And they found broken rocker arm... They found "how fuel can mix with lube oil". After this, I start to study all other things, which is not related to electrical site. BTW, this problem was solved, by replacing cylinder head, we found spare on stock.

Regarging topic subject, - once I install gauges and test engine one more time, i will share results.

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

(OP)

Quote (gruntguru)

Exhaust system is another area you should check for blockage. A pressure gauge at the turbine outlet should read less than 2 psi under load. The pressure before the turbine should be similar to the intake manifold pressure.
Unfortunately I did not find any plugs there to install pressure gauge...

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

Quote (ViCH)

Unfortunately I did not find any plugs there to install pressure gauge...
Then it would be a good idea to add a boss for a gauge. If the metal is thick enough, you can simply drill and tap for a suitable fitting. If metal is thin, find a welder that can drill a hole and weld in a boss for your pressure tap.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Diesel engine can not give more than half load

You can see a clogged intercooler. It should be readily accessible by removing an intake duct or using a borescope.

RE: Diesel engine can not give more than half load

(OP)
Borescope can be used without removing of turbocharger?
If I want to remove intake duct to intercooler, should I drain coolant first?

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

(OP)
hemi, idea is good, thanks. But not in my company. Here I have to raise request for Management of Change to do such modifications.

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

In the pictures you provided there is a duct from the turbocharger that makes a 90 degree turn and then enters the intercooler. If you could remove that elbow you would be able to view the intercooler and inspect it for clogging.

No you don't have to drain engine coolant tomopen ducts and inspect the intercooler.

Edit: looking more closely, it appears the duct is part of the compressor housing so removal of the entire turbocharger would be required.

RE: Diesel engine can not give more than half load

Had an old salvaged turbo charged engine once that idled great but would not rev, found that the hot side of the turbo was spinning
free on the shaft and not driving the compressor. Don't overlook stupid simple stuff.
Does anyone remember the last time that the intercooler was cleaned? If not have them clean it.
The combination of slight restrictions at both inlet and outlet (exhaust filters) could easily cause your issues.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy

RE: Diesel engine can not give more than half load

(OP)
Your turbocharger was multi-spool? Or your shaft was broken?
Another thing - could black smoke waste our turbine waste? If for example, intercooler is clean, then can be turbine dirty vanes be guilty? Several years ago we got problem with fuel injectors, and engine was running several days with excessive smoke.

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

Short answer to your question is yes. That turbo likely has an axial flow turbine wheel, if you have slobber or poor combustion, the spaces in between the vanes can pack up with debris, and then it cokes up on the wheel. The turbo usually doesn't last too long after that starts to happen. One of the reasons I asked you to measure axial and radial runout of turbo, if that is a potential problem then you may catch it before a catastrophic failure occurs, otherwise if you just it progress you end up with a large bill for a major turbo overhaul or replacement.

Looked at the pictures again after Tug's comment, looks like there is a spool piece between the compressor housing and the inlet of the aftercooler. So it looks like just the end bells of the aftercooler can be removed and the core inspected. I'd likely just drop the inlet spool pieces and see if they show signs of oil.

Also, on the picture showing the inlet manifold on the left bank, there is a small pipe attached to the turbo compressor outlet elbow, what does that pipe connect too?

You also mentioned a crankcase fumes disposal system, with part of it attached to the exhaust, can you provide some more details on that? Crankcase fumes disposal system that regurgitate crankcase fumes into the engine, either the intake or exhaust, coupled with extended no or low load runtimes pretty much always lead to problems, at least in my experience.

MikeL.

RE: Diesel engine can not give more than half load

(OP)
Ohh, that small pipe is actuation line to valve for coalescer filter outlet. This is a part of crancase ventilation system. I did not find details in manual, but in theory once compressor increase outlet pressure, it must open valve from coalescer filter to exhaust line. Vacuum from exaust should suck air from crankcase through coalescer. Coalescer will stop oil fumes, accumulate it and pass it down through drain line. Near intercooler at right side, you can see small drum, that is coalescer filter.
Regarding intercooler inspection, prior to do that, I want to test run with pressure gauge installed on compressor outlet first. Wednesday I will update results.

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

(OP)
One more finding (or maybe its normal) - when I removed plug from intake air manifold for pressure gauge installation, I have noticed that end of plug is dirty with soot. Today I decide to recheck - open manifold cover and found soot is everywhere inside, and even collected a small hall of soot nearby cover. Same time, using lighting torch, I noticed that output of intercooler looks like clean (no soot on surface). I thought - maybe soot blocked MAP sensor on other side, and remove cover with MAP/MAT sensors as well. It was dirty, but not clogged. we cleaned soot from surfaces and from sensors, and closed covers back.
BTW, we installed pressure gauge on intercooler inlet. And I found plug on exhaust output, once I find 100mBar gauge, I'll install it there.
So question to experienced mechanical staff: is that soot OK inside intake manifold?

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

Without knowing full history of your engine and its operation, I'd say that looks excessive, inlet systems are supposed to be clean, chunks of soot and carbon material can migrate to the cylinders and cause issues. And all that material has to come from somewhere.

On the aftercooler, looking at the outlet side is not a very good indicator of what is condition is, even just looking at the inlet side doesn't always give you a good idea, most plugging occurs within the core as the compressor outlet air starts to cool. Taking off each end bell and looking thru the core with a strong light is probably the best solution.

MikeL.

RE: Diesel engine can not give more than half load

(OP)
Couldnt it come from combustion of cylinders? If we dont have positive pressure during no-load tests, but we doing it weekly.. We do not have load tests, but we have annual turnaround activities, where engine runs for 2-3 week with 40-45% load.
History.. Few days run with cracked injectors long time ago, few days with broken rocker arm and pushrods on one cylinder 2 years ago. Filters replaced, tappet clearance calibrated. Readings for lube oil and coolant acceptable.

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

2
To the OP. please don't take my post as personal criticism, merely a suggestion on how to move this issue forward. Your posts todate strongly suggest you have one or two serious mechanical deficiencies with this gen set. It is clearly installed at a serious sized industrial facility. You have admitted that mechanical issues are completely outside your area of expertise. Your geographical location seems to be in an area without strong mechanical support.


IMO, you need to advise your management that this standby unit cannot be relied upon to provide power when needed. They can evaluate if the financial consequences are a risk they are prepared to take. Then contact a facility in europe that has the expertise to come in , diagnose the problems and make the necessary repairs.

I can already hear the howls of protest as to how expensive this will be. Thats why management has to make the call as to the costs of losing all power at some point in the future.

RE: Diesel engine can not give more than half load

Did anybody identify the cause of injector failure? What fuel is this running on? Do you have any way of managing any water that's in the fuel? The failed fuel injectors as well as the broken rocker arm (if it's a unit injector) may be symptoms of the water in fuel. Have you inspected the cylinders with the broken components with a borescope? Failed injectors can do a lot of damage to a power assembly.

RE: Diesel engine can not give more than half load

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??

RE: Diesel engine can not give more than half load

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.

RE: Diesel engine can not give more than half load

(OP)
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

RE: Diesel engine can not give more than half load

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

RE: Diesel engine can not give more than half load

(OP)
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

RE: Diesel engine can not give more than half load

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.

RE: Diesel engine can not give more than half load

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.

RE: Diesel engine can not give more than half load

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.

RE: Diesel engine can not give more than half load

(OP)
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

RE: Diesel engine can not give more than half load

(OP)
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

RE: Diesel engine can not give more than half load

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.

RE: Diesel engine can not give more than half load

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

RE: Diesel engine can not give more than half load

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
www.sixstroke.com

RE: Diesel engine can not give more than half load

(OP)
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

RE: Diesel engine can not give more than half load

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

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

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

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

Here is Word Doc of your configuration,
https://files.engineering.com/getfile.aspx?folder=...

(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.

RE: Diesel engine can not give more than half load

(OP)
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

RE: Diesel engine can not give more than half load

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

RE: Diesel engine can not give more than half load

(OP)
I agree. Today my last night shift, after 2 weeks I am going to day shift, and my goal will be to get approval for load test. Anyway, I have learnt much during this troubleshooting, thanks for You all! Once any update or results, I will write here.

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

(OP)
One more question, how engine perform:

1) If AVR and Governor in Droop mode
2) If AVR no droop, and Governor Droop
3) If AVR droop, but Governor not.

Is it major changes will be?

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

1) Both in Droop mode, as real power applied, engine speed will drop, as reactive power applied, voltage will drop

2) Governor in Droop, AVR not, as real power applied, engine speed will drop, AVR will maintain constant voltage even if reactive load applied

3) Governor in Isoch (no droop), AVR in Droop, engine speed will remain constant no matter how much load applied (within limits of engine power rating), as reactive power applied, voltage will drop

Maybe you'll find the attached helpful, also a couple links to some pages with some basic descriptions and some references to some other papers on the subject,
https://www.svri.nl/en/generator-operation-modes/
https://www.svri.nl/en/isochronous-vs-droop-contro...

MikeL.

RE: Diesel engine can not give more than half load

(OP)
Thanks for links and file!
I have read it before, and now understand separate functions of droop and iso, but what is the best combo for single genset? And what is the best combo for 2 parallel gensets? Just refer to your experience. Without grid.

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

(OP)
I mean best combo for stability during dynamic loads switching ON.

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

2
For stand alone operation, a single unit feeding a site load, why have any droop in either the governor or AVR? If governing dynamics are properly adjusted for the loads and capability of the engine and its installed environment, then engine response to load transients is the best it can be. On the AVR, V/Hz (UFRO to some folks) setting is way more important than droop, also dynamic response, again tuned to how the generator excitation and AVR actually respond to the site loads. For many years bulk of my service calls for transient response problems were gensets that still had factory default dynamic settings for both the governor and the AVR. Having an understanding as to what the site loads are actually composed of and how they respond to outage events will dictate how the testing and tuning really need to be done. Problem is most standalone units get dropped on a site, might get a load bank test at some specified load steps and called good if it starts and gets up to speed within the time asked for.

For parallel operation, either island mode plants or paralleling to grid, in my career the predominant method is a combined active real and reactive power sharing control system, such as a Woodward MSLC (if utility paralleling) and/or DSLC's. Also other manufacturer system from Basler, Dief and ComAp or specialized systems for specific applications like Ross Hill controls on drill rigs. Early in my career isochronous kW load share control and either droop or cross current compensation for reactive power sharing was common. I try to move customers away from those system these days if I can mainly due to servicing issues long term, especially if they are still using analog AVR's.

As to your last questions, well there is a whole lot of "that depends" in my response, Usually takes a lot of questions as to what you have and how you operate it. What kinds of loads? Like are you supporting an industrial facility with large motors and a lot of smaller support loads? Maybe a rock and gravel operation with crushers and conveyors. Want a really fun system, how about a multi drill table drill ship with dynamic positioning and a ballast load trim system working in heavy seas? And my experience is all based on mostly RICE prime movers with a turbine unit or two thrown in the mix now and then from 500kW up to about 10MW in size mostly with salient pole synchronous generators. Someone with mostly smaller or larger size experience may have a different set of opinions and experiences.

Hope that helps, MikeL

RE: Diesel engine can not give more than half load

(OP)
Well, genset is discussed one, and loads - a lot of 400V UPS, motors, any domestics.. Plus 11KV 250KW air compressor motors. We need at least 2 unit running. Due to our frequency dropping too high, usually when we start second big motor, we getting underfrequency trip. So our practice now, we start one compressor, offload it, then start second, load first, and then only we start to energise LV loads.
If we will make governor running in ISO, could it help?

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

No, governing in isochronous should not help. Properly configured, speed droop governors should run at 51.5 to 52.5 hz at zero load and not drop below 50 hz at 100% load. The frequency should never be low enough to cause a trip in either case. Isochronous governors operate the same as droop governors during a load change but have a compensation circuit to return the frequency to nominal after the load change.

When running two units in parallel it's typically to run one in isochronous and one in droop mode. The droop engine will run at constant load and the isochronous will take any load changes. This prevents the units from competing for the load.

RE: Diesel engine can not give more than half load

(OP)
That governor 723plus has jumper on terminals 9-10. This terminals is for LOAD SHARING SIGNAL. I have checked many manuals of Woodward 723+, but didnt found purpose of jumper. If i do not need load sharing, should it be jumped or remained open?

Viktor
Electrical Technician II

RE: Diesel engine can not give more than half load

For 723 governors with load sharing, if not used a jumper is installed, jumper should have been there from the beginning.

MikeL.

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