"We have to remember the basics before getting a real handle on emissions control for large marine and stationary plants," says one well-known marine industry commentator. "In today's world of automation and electronic control of engines, the importance of the old time practice of stepping on deck and taking a glance at the stack before assuming the watch, be it a steam or motor plant is often forgotten," says Ronald M. Oyer, in an opinion piece written for MARINE LOG;
Mr. Oyer's remarks appear below:
The challenges of regulations such as those introducing first SECA's and now ECA's have awakened the maritime community to the needs for some drastic changes in the way we operate. Bolt on solutions or the old "mechanic in a can" approach just won't make compliance a snap. Large land based diesel power plants will require some catch up as well.
The operational challenges involving the use of low sulfur fuels can be minimized through simple modifications and most importantly through prudent operating practices by shipboard staff.
When operational issues are encountered, panic runs amongst the regulators, many of whom are not familiar with the everyday operations of today's plants.
There have been reports of large HFO plants failing to start on distillate fuels when maneuvering or inability to maintain power at low speeds. The root cause of these reports? Wear in internal components of the injection pumps and nozzles resulting from operating on residual fuels. Can this be avoided? No, wear cannot be avoided however; the effects of residual fuel use can be minimized through prudent fuel purchasing and the tightly controlled operation of the plant's fuel handling equipment such as separators and filters.
There is no plausible excuse for not knowing the "health" or condition of your plant prior to a maneuvering situation. Wear in fuel pump internals is easily identified through monitoring of fuel rack index and is indicated by a gradual increase in rack index for a given engine load and vessel trim condition. Average rack positions for all maneuvering bells and sea speed should be taken and recorded in both ballast and loaded situations. They can then be posted at the maneuvering station for handy reference.
For those flying first class with one of today's electronic engines, most ECU's (electronic control unit) can provide reference to fuel rate index which can be correlated to maneuvering bells and sea state operations. While the majority of problems arise in low speed two stroke plants, four stroke plants can experience similar situations. The bottom line indicates that injection system maintenance cannot be scheduled by operatinq hours alone and continuous observation may indicate significantly shorter operating periods based on the quality and handling of fuel used.
Other problems that have been reported are the inability to start or maintain power while operating on distillate fuels and lock up or failure of the injection system when shifting from HFO to distillate prior to entering port. Two factors are involved here, the first being the advent of unifuel plants and modern heavy fuel injection systems.
Years' back, shifting to distillate fuel prior to maneuvering and shut down was common practice. With advances in fuel valve design, changeover was not required unless fuel system maintenance was planned. The finesse of fuel changeover was lost in the process. That has changed with the implementation of ECA's and Californian regulations requiring operation on low sulfur or distillate fuel and the inevitable change over procedures.
The second area of importance is again wear of the fuel injection system internals. Increased internal clearances and lower viscosity of distillate fuels results in increased internal leakage, a factor compounded by increased wear. One point to remember is that all large marine and stationary engines are tested and certified using distillate fuel on the test bed, in some cases MGO (DMA) and in others MDO (DMB). The start/stop certifications, output, etc. are all made using these fuels. As to injection viscosity, 2 cst is a rule of thumb value as the minimum for safe operation on distillates. While the challenges of change over from HFO to MGO/MDO are the same as they have been for years, this can be minimized -- again through proper crew training and prudent operations.
OEM's such as MAN B&W have the "Diesel Switch" a system designed to make the change over and challenges of temperature differential simpler. However, the skills required for a manual changeover cannot be over emphasized as an engineer must always be ready to respond if an automated system fails. The issue involving the inherent high temperatures that can remain even after changeover to distillate can be minimized or eliminated through a simple plate cooler installed in the distillate loop to lower temperature of MGO/MOO and increase its injection viscosity.
Regulators report the incidence of operators asking for exemptions or waivers from the requirements for low sulfur fuels or particularly the use of distillates, though the majority of operators make every attempt to comply. While they do endeavor to make exceptions in the rare case, they are also aware of the consistent applicant aka those who "cry wolf' a bit too often. Enforcement agencies make note of those who consistently apply for such exemptions. A simple search of a vessels detention history on a reputable maritime intelligence database offers significant informative insight into the general conditions of its machinery and the creditability of its owners/operators. The risks to maritime safety and the environment are far too important for questionable maintenance and operating practices.
To summarize, an engineer must at all times know the "health" of the plant and be up to speed on the latest in both operational and maintenance practices. Keep abreast of the latest service letters from your respective OEM. Compliance will not be easy and as an increasing array of emissions reduction systems come on line the importance of maintaining and operating a plant within design criteria cannot be over emphasized. The regulations are in place for the benefit of everyone's environmental health and they will not be going away.