5 x Fuel Forwarding Pump Skids for Gas Turbine Powerplant

In our latest case study, we’re going to discuss one of our largest commissions ever. This was a major project based around a gas turbine power plant fuel transfer system for a power station in Angola in central Africa. 

We were contacted by a leading engineering contractor which was working with the team at the Angolan power plant. They were looking to increase diesel fuel supply flow rates, as they were boosting the number of gas turbines from three to six. 

What are gas turbines and what do they do? 

A gas turbine is a combustion engine at the heart of a power plant that converts natural gas or other liquid fuels to mechanical energy.  

As hot combustion gas expands through the turbine, it spins the rotating blades. The rotating blades perform a dual function: they drive the compressor to draw more pressurised air into the combustion section, and they spin a generator to produce electricity.  

What are the three main components of gas turbine? 

Combustion gas turbines at the heart of many modern power plants are complex machines, but they basically have three main sections: 

1. The compressor 

In the compressor section, air is drawn in, compressed up to 40 times ambient pressure and fed into the combustion chamber at hundreds of miles per hour 

2. The combustion system 

This is typically made up of a ring of fuel injectors that inject a steady stream of fuel into combustion chambers where it mixes with the air. The mixture is burned at temperatures of over 2000°F. This combustion produces a high temperature, high pressure gas stream that enters and expands through the turbine section 

3. The turbine  

This is a complicated arrangement of alternate stationary and rotating aerofoil-section blades. As hot combustion gas expands through the turbine, it spins the rotating blades. The rotating blades drive the compressor to pull in more pressurised air, and they spin a generator to produce electricity. 

So in effect, a gas turbine works on the same principle as a simple petrol or diesel combustion engine with the same cycle:  intake, compression, combustion or expansion, and exhaust. 

What fuels are burnt in a gas turbine? 

In all modern gas turbines, the pressurised gas is created by the burning of a fuel like natural gas or various paraffins like methane, ethane, propane, petrol or kerosene oil. Of these, petrol and kerosene or a blend of the two are the ones used most often. 

Diesels can also be used in a gas turbine. In addition, oils can be burnt including crude oil and other refined residuals that are heated to produce the required viscosity for gas turbine combustion. 

What did the client want from North Ridge Pumps? 

We were asked by the engineering contractor working with the power plant team to supply five fuel forwarding pump skids for the fuel transfer system at the gas turbine power station in Angola. 

They wanted each prefabricated pump skid to consist of duty and standby pumps mounted within a skid frame for the bulk transfer of diesel at around 1000L/min. Fuel transfer skids are a very efficient way for operators to simplify the bulk transfer of fuels like diesel. They are built as one self-contained unit which can essentially be plugged into the production process and activated. 

Here at North Ridge Pumps, we’re not tied to a single pump technology, so we can provide the best pump for a particular application at the lowest lifetime cost. In fact, we can use our expertise to offer a bespoke solution, not something straight off the shelf. 

We assembled each fuel forwarding skid with a duty/standby vane pump, base plate, integrated strainers, control panel and oval gear meter which enabled the power plant team to simply drop the units into place. 

The power plant operator had used centrifugal pumps in the past. However, we recommended positive displacement pumps instead as these removed the need for lots of ancillaries and accessories. The vane pumps we specified were our NR-BAL rotary vane pumps which are positive displacement pumps designed to handle the vast majority of low to medium viscosity fluids.  

Designed for the oil and gas industry 

Thanks to their proven efficiency and heavy duty design, our rotary sliding vane pumps are widely used within the oil and gas industry. They can also be operated in reverse meaning that the suction can become the discharge side if required. This particular feature makes them ideal for fuel transfer, loading or unloading applications. 

Each pump type within our NR-BAL range has its own unique features. The NR-BAL-2R model for instance, is fitted with double mechanical seals for extra protection. This means that the chance of leaks on this pump is virtually zero, making this particular model very popular for transferring highly flammable liquids as in this particular application. 

Constant flow rates 

As we assembled each bulk transfer prefabricated pump skid to incorporate vane pumps, the power plant operators could rely on constant flow rates regardless of changes in back pressure.  

We prefabricated each fuel transfer pump skid to include a control panel for local and remote operation to enable full pump control, varied flow rates, pressure control and full 24/7 visibility of working conditions. 

Each fuel forwarding skid unit incorporated: 

• Strainers for pump protection at the inlet 

• Mounts to prevent vibration of the skid during operation especially at specific frequencies 

• Remote pressure sensors wired back to the panel and also gauges for pressure visualisation for operators to see 

• Expansion joints on the pump discharge and suction, to further dampen pressure surges or vibration of the skids 

• The panel was specifically manufactured and configured to allow 7” touch screen operation for full control and visibility of the complete system and included: 

• Local and remote control of flow  

• Visibility of inlet and outlet pressures both via panel and on the actual skids for easy troubleshooting 

• Local and remote emergency stop with Run, Pause and Fault LED beacons  

• Quality components throughout including Schneider/ Danfoss instrumentation 

• Additional thermostat activated internal cooling  

• Anti-condensation heaters to protect electrical equipment  

• A stainless steel IP55 enclosure 

• Specific operating and user manuals for the complete system written in clear British English with screenshots 

What’s more, the panel enabled anyone at any location worldwide to access the system remotely. This makes it easier to provide expert assistance if this is needed during testing, commissioning or troubleshooting  

Above all, having North Ridge Pumps supply the pumps, instrumentation and panel made the whole process easier. It meant there was just one company responsible for specification, design and build, and more importantly a single contact for commissioning advice and troubleshooting. 

If you’re looking for an all-in-one prefabricated pump skid to accelerate and automate liquid transfer cost-effectively, speak to North Ridge Pumps to see how we can help.