Light Fuel Oil Transfer Pump Set for Power Generation Facility

In our latest case study, we’re discussing a recent project for the supply of two pumps for a large power generation business with operations overseas.

A potential client got in touch with us about two light fuel oil pumps to be used for the transfer of light fuel oil, also known as diesel oil. It was to be pumped from main storage tanks to day tanks at their sizeable power generation facility abroad.

What is light fuel oil?

Light fuel oils or diesel oils are high value distillates that can be used to drive diesel engine power plants, both in stand-by operation and baseload applications.

There are various grades available depending on use, with low fuel duty variants of diesel known as red diesel due to the red dye incorporated in its mixture. Red Diesel is often used in the forestry, rail and agricultural sectors.

Light fuel oil is often employed in back-up power plants and installations on remote islands or in arctic conditions where it’s difficult and costly to supply cheaper alternatives. Light Fuel Oil requires less processing and produces a higher percentage of petrol and diesel than heavy oil. Its viscosity can range between 1 and 7cst, so it can be comfortably handled by a variety of technologies.

What’s a day tank?

In a power generation plant, bulk fuel is usually stored in a large tank and then transferred to a smaller day tank near the engine.

The day tank is positioned between the bulk storage tank and the diesel engine, and the fuel is delivered from the bulk storage to the day tank by a bulk storage delivery pump.

Why is it needed?

In the area of power generation, the day tank is crucial and plays a key role in maintaining continuous operations. It ensures uninterrupted power supply to essential systems, facilities and services.

In one application, the day tank is specifically designed to provide a generator with a constant and reliable fuel supply for short-term operations.

Unlike much bigger bulk fuel storage tanks, which store fuel for long periods, day tanks are smaller and provide fuel for around 8 to 24 hours. They are positioned close to the generator, so that they can provide fuel quickly and efficiently during power outages or emergencies.

The benefits of a day tank

Uninterrupted power supply

In critical applications such as hospitals, industrial plant and data centres, even a very short power interruption can have disastrous, even fatal consequences. Day tanks fill the gap between the main fuel storage tank and the generator. They ensure that there’s a continuous fuel supply so that the generator can kick in straight away if the main power source fails even briefly.

• Cost effectiveness
  

Day tanks minimise downtime and cut the risk of equipment damage caused by power interruptions. This all helps to boost overall plant efficiency and reduce the cost of unplanned power cuts.

• Fuel quality and maintenance
  

By storing a limited amount of fuel, day tanks turn fuel over more frequently, reducing the risk of fuel degrading or becoming contaminated. In addition, day tanks often have built-in filters and monitoring systems which clean the fuel and give an early warning of any potential issues - enabling quick troubleshooting and maintenance.

• Efficient use of space
  

Where bulk fuel storage tanks usually need large amounts of space and infrastructure, day tanks are compact and can be fitted easily into small spaces. What’s more, their proximity to the main storage tank means there’s no need for long fuel lines, and less risk of fuel contamination or leaks.

What’s a gear pump?

It’s a rotary positive displacement pump that comes in two designs: internal eccentric or external, also known as helical gear.

The right design for any particular application will depend on the viscosity of the fluid being pumped and the pressure required. That’s because the internal design changes according to the fluid type, with different styles of teeth fitted to suit different operating conditions. These then affect the rotational speed of the pump.

How does a gear pump work? 

Both internal eccentric and external gear pumps have two idler gears. The gears are mounted one above the other, with one being driven by the motor.

The gears are synchronised to mesh together with fluid flowing into the open cavities and being trapped by the teeth as they rotate. As the fluid takes the path of least resistance, it flows towards the meshed areas where it’s discharged.

Gear pumps are very versatile being self-priming up to 6.5m. They have a positive displacement design which creates a non-pulsating flow, and can comfortably handle viscosities between 1 CST and 1,000,000 CST.

Specific project requirements

As part of the project brief, our client specified the use of rotary gear pumps as part of the light fuel transfer set for their power generation application. They also wanted a capacity of 20 to 30m³h without having to alter their existing 3-inch pipework, which we could achieve with a pump speed of just 350rpm.

Here at North Ridge Pumps, we’re not tied down to a single pump technology. We use our expertise to offer a tailor-made solution, not something picked off the shelf. This means we can always select the best pump for any particular client and application - at the lowest lifetime cost.

Using gear pumps for bulk fuel transfer to a day tank

The fuel transfer pump from the bulk tank to the day tank is generally a positive displacement gear pump positioned above the bulk tank.

When the pump is started, the air in the suction line is removed and a vacuum is created. This lifts the liquid in the bulk tank up into the suction pipe and into the day tank.

Our FIG90 internal gear pump with 90° flange connections

For this light fuel transfer set, we quoted and supplied two of our industrial long-coupled internal gear pumps - our FIG 90 model.

The casing was manufactured from cast iron and the gears from ductile iron. This ensured that we could achieve an outlet pressure of up to 12bar. Our light fuel oil pumps were completed and despatched to the client in 8 weeks.

Our internal gear pumps are designed to handle clean lubricating fluids of various viscosities – ranging from 2 to 7 times the thickness of water. To handle this variety of fluids, we specified and supplied the pumps with a relief valve which would ensure a consistent flow regardless of fluid viscosity.

For this particular application, the pumps would be transferring light fuel oil. Our internal gear pumps can also be used for pumping resins, adhesives and greases.

Excellent efficiency

Our straightforward design with only two rotating components, together with the exceptionally tight clearances of the internal moving parts means that there is almost zero slip while the internal gear pump is operating.

This means that our gear pumps are not only highly efficient, but they use very little energy. This makes them the perfect solution for applications which require 24/7 continuous operation.

If you have an application or operation which involves the transfer of fluids, solids or viscous liquids, and don’t know which pump to specify, speak to North Ridge Pumps to see how we can help.