5 Practical Advice for Professional Marine Engineers on Improving Boiler Efficiency

5 Practical Advice for Professional Marine Engineers on Improving Boiler Efficiency

One of the most important responsibilities of marine engineers on board ships is to ensure that all machinery systems are operating properly. Each piece of machinery in the engine room is reliant on a variety of factors that determine its overall efficiency and performance.

The boiler is an important piece of machinery in the ship’s engine room that requires special attention because it supports several other operations and machinery, including the main engine. Boiler Parts maintenance and improvement of their efficiency requires taking note of a number of factors

The following are five critical factors to consider when attempting to improve boiler efficiency.

1. Feed Water Temperature

It is critical to maintain the standard of all the system’s inputs in order to improve the efficiency of any system. The feed water in a boiler system is crucial in determining overall efficiency.

The feed water temperature must be kept at approximately To ensure that the boiler runs efficiently, set the temperature to 80-85 degrees Celsius. Any decrease in water temperature results in more time spent heating the water to produce steam, increased fuel consumption, and a decrease in overall efficiency.

The hot well must be monitored to ensure that the temperature and level are correct. Any sudden drop in the level of the hot well necessitates the addition of more cold water to maintain the level, resulting in a reduction in the feed water temperature.


  • Feed water temperature should be kept between 80 and 85 degrees Celcius.
  • Check to see if the hot well level controller is working properly.
  • Keep an eye on the temperature of the feed water via the hot well.

2. Supply of Air/Steam to Burner

Air/steam are required to ensure that adequate fire is generated inside the furnace via good combustion. For efficient combustion, it is therefore critical to understand the air/steam percentage. 15-20% by weight of air is required for efficient combustion in fuel oil fired marine boilers with register type burners.

Excess air must be kept within a certain range to reduce flue gas losses. Every 1% reduction in the amount of excess air supplied to the furnace results in a 0.6% increase in the overall efficiency of the boiler.


  • Excess air/steam must be reduced or eliminated.
  • Determine the stoichiometric air fuel ratio for your boiler’s current rating.
  • Using a flue gas analyzer, monitor the content of combustion gases and adjust the air fuel ratio accordingly.

3. Structural Importance

The boiler is a high-pressure vessel that generates high-temperature steam for a variety of applications.  Boiler Parts such as the outer shell or structure not only contain the pressure but also maintain the temperature of the flue gas inside the boiler for improved heat exchange.

Things to Check:

  • The boiler shell’s leakage must also be investigated. This is caused primarily by deformation or bulging of the shell, which results in cracks and leakage.
  • The boiler’s insulation must be inspected for damage or leakage.
  • The condition of the refractory should be checked at least once a month. Any refractory damage will cause localised heating of the shell and damage to it.


  • As soon as possible, inspect the refractory and replace any damaged refractory.
  • Examine the boiler’s outer plates for any black spots. This indicates that the boiler shell is cracked and leaking.
  • Ensure that the shell’s insulation is properly maintained in order to reduce heat loss and maintain boiler efficiency.

4. Blow Down Control

Typically, boiler blow down is not performed on a regular basis by operators. Blow down is only performed if the chloride levels in the water are high or if a high conductivity alarm is triggered. As a result, uncontrolled continuous blowdown occurs, resulting in a waste of boiler heat and efficiency. Furthermore, it reduces the amount of high-temperature water inside the boiler while increasing the amount of moderate-temperature water from the hot well.

To maintain the steam pressure, the boiler burner will now fire for a longer period of time, increasing fuel combustion and lowering efficiency. It is recommended that regular short-term blowdowns be performed to not only maintain the chloride level but also to reduce thermal stresses within the boiler.

Pro Tips:

  • Avoid long periods of blowdown.
  • Short blowdowns should be performed on a regular basis.
  • Keep an eye on the chloride content of the boiler water on a regular basis.

5. Boiler Loading

Ships with multiple boilers or steam generators must ensure that the boiler load is not too low or too high. The best operating range for maximum boiler efficiency is two-thirds of the full load of the boiler.

When the boiler is operated at less than 50% of its maximum capacity, more air is required to burn the fuel, increasing the sensible heat loss. It is always preferable to run fewer boilers at high load than a greater number of boilers at low load.

Pro Tips:

  • The highest efficiency of the boiler can be achieved at two-thirds of full load.
  • Running the boiler at less than 25% load reduces efficiency significantly.

Through following these simple tips, professional marine engineers can keep the boilers running at peak efficiency. Regular maintenance and care will help to prolong the life of the boiler and keep it efficiently running for years to come.

Sheri gill