08-06-2012 11:16 AM
Really depends a lot on three factors, you application, installation specifics and the actual fuel you are using.
In general heating the jacket water keeps the engine cylinders and heads warm, allows easier starting, reduces corrosion due to condensation, and in some engines help facilitate lube oil flow to some areas of the engine during prelubeand initial engine start.
Short term the likely impacts are startability, do you start the engine on diesel then switch to HFO for run, or start and stop on HFO? If you start and stop on diesel, at least in my experience, the need for jacket water heating has less of an operational impact. If you have a better quality fuel, or treat it very well, then starting and stopping using the HFO may be helped by proper preheat temperatures to improve engine starting and running. Also, how fast do you need to be up and on line after inital start? Preheating can reduce warm up times in many applications.
Longer term, depending on actual engine run times, engine preheating may reduce the effects of corrosion, and reduce the impacts of thermal cycling, which can contribute to leaks and gasket/seal failures. HFO engines are typically run in poor operating environments, like marine applications, power plants in developing countries or in some cases I've actually seen used to reduce waste streams, like old lube oils. If the engine runs all the time, no real need for preheating, but if it sits for extended periods of time then the preheating if properly done may help extend engine life.
Some fuels classified as HFO can be very heavy, have high contaminant levels, or lots of corrosive by products, in the case of really poor fuels, keeping the engine warmed can have a benefit even during short shutdown periods.
Hope that helps, Mike L.
08-29-2012 05:11 PM
i have two main problems that might relate back to preheating, one is wear of the block at the contact points of the cylinder liner(liner landing and bottom bore the other is high piston crown ring grove wear in the upper ring grove.)
08-30-2012 12:10 AM
The wear issues you describe I wouldn't normally associate with a preheating problem. Could you provide a bit more info about your application? Propulsion or generator? What kind of heavy fuel, like 180 cst, 350 etc? Are you seeing these problems on all cylinders? How many hours?
08-30-2012 01:34 PM
Power plant using 380 cst fuel engines range from 45,000 to 52,000. problems with the block or on different cylinders and different eninges problem with ring grove wear is on all 13 engines.
09-01-2012 11:39 AM
Hard to speak to the block wear at the liner contact areas, although it would indicate relative movement between the liner and block during operation, so things like assembly, liner flange tolerences, excessive combustion pressures could all come into play. Have you been in contact with the appropriate service engineering people at CAT and/or Mak? I saw some similar wear issues several years ago on a site with 3600 HFO engines where the engines started and stopped many times a day, but I think that would be an extreme example.
On the top ring groove wear, is it the likely result of higher levels of carbon deposits that are usually associated with HFO or residual fuels? You're using a pretty heavy fuel, depending on the levels of bottoms and how the cylinder deposit rates are, it may be a consequence of the type of fuel you are using. At 380 cst, do you start and stop on DFO or MDO then switch, or do you start up and shut down on HFO? What kind of start/stop frequency, daily, weekly, monthly?
Frankly these are pretty difficult questions to answer remotely, to properly evaluate you really need to look at long term operational history, fuel and oil consumption rates, actual analysis of the worn parts, and several engine performance parameters, such as cylinders temps and combustion pressures.
If you have 13 engines you have a pretty significant population, I'm sure if the right person at CAT could be contacted you should be able to get some better answers, or at least a plan to better evaluate and determine root cause of the problems.
Good luck! Mike L.