Wartsila 18V50 Running Data – Key Insights

Discover essential insights from the Wartsila 18V50 running data of engines. Get a comprehensive overview of performance and operation.

Wartsila 18V50 Running data

ENGINE SPEED

• Measured by camshaft wheel or flywheel.
• Unstably, engine speed can be caused by wrong governor settings worn/jamming regulating mechanism.
• Alarm/safety blockings.
• Safety functions: over speed.

TURBO CHARGER SPEED

• This is an important factor to follow since the turbo speed gives an indication when the nozzle ring gets dirty. I.e. the turbo speed increases slightly.

FUEL RACK POSITION

• Indicates the amount of sprayed fuel oil (engine load).
• Increased fuel rack index (same load) can be the result of the worn pump (bigger internal leakages), a change in fuel quality, or a lower heat value.

IGNITION QUALITY PARAMETERS

1. Energy
2. Viscosity
3. Maximum firing pressure.
4. Injection delay
5. Ignition delay

ENERGY COMPARISON

• The injection pump is a volumetric pump.
• The higher the density, the more energy it contains per volume unit.
• The density difference between HFO and MDO is larger than the difference in net calorific value.

VISCOSITY COMPARISON

• The viscosity of MDO is lower than the viscosity of HFO (even HFO is heated)
• Lower viscosity fuels result in more internal leakage in the injection pump from the high-pressure side to the low-pressure side.
• Internal leakage has to be compensated by giving more fuel racks.

MAXIMUM FIRING PRESSURE

• Depending on the charge, air pressure
• To achieve proper combustion, the firing pressure has to be high and thus also the charge air pressure.
• Timing of the fuel pump

• INJECTION DELAY is the time it takes to build up a pressure higher than the opening pressure of the nozzle
• The delay is comparable to the condition of injection equipment
• IGNITION DELAY is the time gap between the commencement of injection and the commencement of ignition.
• Depending on the fuel quality
• Compression temperature has a big influence on the ignition delay
• Compression temperature is not high enough for the fuel to ignite longer ignition delay

HIGHER PEAK PRESSURES AND HIGHER EXHAUST GAS TEMPERATURES

• Normally, 1…2 ° of crank angle.
• Too early timing of injection
• Higher peak pressure

EXHAUST GAS TEMPERATURE AFTER CYLINDER

• Measured individually after each cylinder
• Each cylinder has two measuring points.
• The average temperature of all exhaust temperature sensors is approximately 100 °C lower than the exhaust gas temperature before the turbine.
• Maximum allowed difference between valves in one cylinder.
• Maximum allowed difference of one cylinder average from the average of all cylinders, alarm.
• In normal operation, the average temperature Cylinder temperature deviation can be up to 30 – 40 °C.
• The engine is (depending on installation) provided with a safety slow-down arrangement if the temperature difference is too big.
• A 10 °C increase in ambient temperature will result in approximately 15 °C increase in exhaust gas temperature.

EXHAUST GAS TEMPERATURE AFTER TURBOCHARGER

• Indicates the kinetic energy of the exhaust gases that are running the turbine
• Indicates the condition of the turbo, i.e. scavenging of the engine
• If a de-Nox catalysator is installed, the temperature has to exceed a certain level to ensure the function of the catalysator.

PRESSURE DIFFERENCE OVER THE CYLINDERS:

• Measuring the pressure difference between the charge air manifold and the exhaust gas manifold. Indicates how well the scavenging works.
• Depends on the turbocharger. Therefore, the values below should be considered as allusive.
• The bigger the DP is, the better the scavenging.
• The normal value with a 100% load varies depending on installation. Once the value has been dropped down, it is an indication that something is wrong with the engine -e.g. dirty nozzle ring & turbine.

DIRTY CHARGE AIR COOLER:

• As indicated by the increase of the pressure difference over the cooler, remember that the dirtiness of the cooler aggravates the cleaning of the cooler.

CONSEQUENCES:

• Less fresh air to cylinders
• Higher exhaust gas temperatures
• Improper combustion
• Low peak pressures
• More deposits to the nozzle ring
• Increased SFOC
• Increased SLOC
• Higher fuel rack reading at the same load

CONDENSE WATER IN CHARGE AIR:

• Condense water that is condensing in the cooler has to be drained out
• Causes wear in the pistons, piston rings and cylinder heads
• Will cause inlet seat ring problems
• The amount of condensed water may be reduced by increasing the charge
• Air temperature, but the maximum temp must not be exceeded, which is 55 ° C
• Increases thermal loading of the engine

DIRTY NOZZLE RING:

• Indicated by;
• Slightly higher turbine speed
• Higher receiver temperature
• Decreased pressure difference over the cylinders

POSSIBLE CONSEQUENCES

• Remainder pressure in the cylinders increase
• less fresh air to cylinders
• worse scavenging
• delayed combustion
• more deposit accumulations
• higher exhaust gas temperatures
• increased thermal load
• increased risk of engine failure
• piston seizure
• hot corrosion
• increased fuel consumption.

LOW PEAK PRESSURES-HIGH EXHAUST GAS TEMPERATURES:

• Obvious reason:
• DELAYED COMBUSTION
• Dirty air cooler
• dirty nozzle ring(s)
• injection nozzles in bad condition
• worn injection pumps
• a long injection delay
• bad fuel
• high CCAI value, poor ignition properties
• high water content
• high exhaust gas temp

HIGH EXHAUST GAS TEMPERATURES

• Injection valves in bad condition
• dirty nozzle ring
• dirty air cooler
• Low fuel viscosity
• worn injection pumps
• bad fuel
• burned valves or seats

HIGH FUEL RACK READING COMPARED TO LOAD

• Worn injection pumps
• more internal leakage
• too low viscosity of the fuel
• more internal leakage
• low heat value of the fuel
• high water content
• dirty fuel filter
• too low fuel pressure
• big fuel leakage