Viscotherm with Differential Pressure (DP) Transmitter:

• The viscotherm consists of a capillary tube connected to the discharge side of a gear pump driven by an electric motor.
• A DP transmitter measures the pressure difference in the capillary tube, which is directly proportional to the viscosity of the fuel oil.
• The fuel oil passes through a heater controlled by a steam valve. The valve adjusts the steam flow to maintain the desired fuel viscosity.
• A controller compares the measured viscosity from the DP transmitter to the set point and sends a signal to regulate the steam valve.

• As fuel flows through the viscotherm, the gear pump diverts a portion of the fuel through the capillary tube.
• The DP transmitter measures the pressure difference across the capillary tube.
• The DP transmitter sends the viscosity data to the controller.
• The controller compares the measured viscosity to the set point value.
• If the viscosity deviates from the desired level, the controller adjusts the steam valve to increase or decrease the steam flow to the fuel heater.
• Adjusting the steam flow changes the fuel temperature, directly impacting viscosity to maintain optimal levels.

• Modern two-stroke engines are equipped with fuel circulation systems that ensure the fuel at injectors is always maintained at the correct temperature and viscosity.
• Continuous circulation eliminates the need to switch between HFO and low-sulphur fuel oil (LSFO) under normal conditions.

Advantages:

• Significant savings are achieved as residual fuel is cheaper than distillate fuel.
• Reduces the complexities and risks associated with frequent fuel changeovers, such as thermal shock and injector clogging.

Where local regulations demand the use of VLSFO, changeovers may still be necessary. However, automated systems simplify this process.