Slow Speed Diesel (APL)


BackgroundThe trial was run on both the main engine and aux. engine. The main engine was a Sulzer 12 Cylinder RTA-84 Slow Speed Direct Drive Marine Diesel Engine rated at 53,000 BHP at 95 RPM.

The aux. engine is a MAK 8M-453C, a medium speed diesel rated for 2500 KW at 600 RPM. The engines were on the MV President Kennedy, a vessel owned by American President Lines at the time of the trial.

The purpose of the trial was to see if these engines could burn fuel with over 400 ppm vanadium without any more problems than they normally saw when burning fuel with between 30 and 200 ppm vanadium.

The trial was to see if it would be possible to buy cheaper fuel with high vanadium, purchase a Bycosin product called MP-4, a combustion catalyst and ash inhibitor to reduce ash related problems, and still save money.

Under normal conditions, when one of these engines burned fuel that was higher than 200 ppm vanadium there was a tendency to plate vanadium ash deposits on exhaust valves and the nozzle ring inlets to the turbochargers.


Test Proposal

Test ProposalBycosin proposed that a trial would be run with Bycosin MP-4, a product with a lot of documented data that demonstrated its ability to reduce vanadium related problems.

We proposed that prior to the beginning of the trial, the crew pull 2 pistons on the main engine to measure piston crown burn down, piston ring lands, piston rings, piston rods, piston rod stuffing box segments and the cylinder liner.

Visual inspections should be carried out on the cylinder head, exhaust valve conditions, deposits before and after the turbocharger nozzle ring and the turbine wheel and all other piston and cylinder conditions as viewed from the scavenge space under the pistons.

All spaces and machinery condition should be noted. On the aux. engine, two cylinder heads were to be lifted and the turbocharger disassembled.

Cylinder liner, piston, valve and turbo- charger conditions are pictured below.




Bycosin MP-4 Combustion Catalyst contains both iron for combustion and an oil soluble magnesium to reduce the impact of ash in the fuel.

MP-4 is particularly effective in treating fuel high in Vanadium, Sulfur, Sodium and Calcium (from lube oil). This product normally doses at 1:3000.



Test Proposal

Prior to the trial starting, the proposed inspections were performed on the main engine and minimal deposits were noted at the start of testing. No deposits were witnessed on the exhaust valve or valve seat.

Normal carbon deposits were evident on the piston crowns and the cylinder covers. On the aux. engine, conditions noted a slight buildup of deposits both on the intake and exhaust valves as well as the turbocharger nozzle ring and the turbine blades.

The trial began when the vessel took a load of fuel with 417 ppm vanadium on August 22. The fuel was dosed at 1:2800. Inspections were carried out after the first voyage and all conditions were considered normal with no increase in the amount of deposits.

The next voyage, the fuel had 443 ppm vanadium and the MP-4 was added at 1:3100. Almost immediately difficulties were en-countered with burning this batch of fuel. Upon returning to the port after the voyage the inspection noted deposits on the exhaust valves and the exhaust valve seat of both engines. Scrapings of deposits on the main engine piston, top of the crown, side of the crown and in the top ring groove was sent off for analysis.

Although an increase in deposits and a decrease in visual conditions were noted, no wear measurements had increased dramatically and thus a decision was made to carry on with the high vanadium fuel for one more voyage.

The final voyage had fuel with 392 ppm vanadium and the MP-4 was dosed at 1:2500. The dosage was increased due to the engine conditions of the last voyage. Upon returning from the voyage all engines parts that had been opened before were opened again. Conditions had improved dramatically from the previous voyage.




Final test report showed that the engines were cleaner after the trial than at anytime in their history and that indeed, it was possible to burn high-vanadium fuel with MP-4 and not have problems.

Conclusions noted by the Port Engineer:

• Dosage should be determined by the vanadium ppm. The higher it is, the higher the MP-4 dosage.

• Following three voyages with high vanadium fuel, the engine was cleaner than it had ever been in its history.

It was shown that it was possible to successfully burn high vanadium fuel when using Bycosin MP-4.