Swiss-Made Gas Turbine Fuel Skids
Since its establishment in 1995, the Swiss company Enerproject, has been specializing in the design and manufacture of gas turbine fuel skids. To date, the company has delivered more than 200 skids to fuel aeroderivative and heavy-duty gas turbines made by companies such as GE, Kawasaki, Siemens and Solar. These turbines are installed in many different countries with many different climates and fuel characteristics.

Initially, Enerproject built up experience by providing fuel skids for turbines used only in the power generation sector, which requires a high degree of standardization. Soon after, they extended their business to cover requests forthe oil and gas industry as well.

Mechanical drive gas turbines that are used in the oil and gas sector require a fuel skid with a higher degree of sophistication, not only to handle the environment but to adjust to the quality of fuel gas available. This is especially true in the upstream sector where the natural gas is untreated and can contain contaminants.Enerproject experts are available to team with gas turbine manufacturers Coalesto engineer the best solution for any particular application.

The fuel skid has the main task of handling the gas at the pressure and volume requested by the turbine fuel system. The heart of the system is the compressor, which is usually driven by an electric motor. Compressors used for this function can be centrifugal, rotary vane or oil-injected screw type, which according to Enerproject, is usedin the great majority of applications.

It is imperative for a turbine fuel system to receive clean, oil-free gas. According to the company, Enerproject’soil separation and filtering system guarantees a delivery of fuel gas completely free from oil, and in most cases, cleaner than what was received from the pipeline to be compressed.

At the skid entrance, located upstream from the oil-injected screw compressor, the gas flow passes through a two-stage scrubber-filter with a filtration degree of 10 micron in order to capture possible solid particles intermingled with the gas.

Downstream from the fuel gas compressor, the gas enters a vessel containing a centrifugal oil separator with a 98% efficiency and a three-stage coalesto cent filter that reduces the oil content in the gas to 1 ppmw. After leaving the vessel, the fuel gas is cooled and passed through two more coalescent filters, which ensures the effectiveness of the separation system and guarantees that the liquid content in the skid exit is reduced to 0.1 ppmw.

However, the fuel gas skid is usually placed at some distance from the gas turbine and in the connecting line the gasmay cool down and form some condensation, which is captured in a fourth coalescent filter placed just in front of the turbine. That way, the fuel gas delivered to the burners has a liquid content of 0.01 ppmw, which is practically non-existent.

All the skids are provided with a separate gas cooling system that controls the gas temperature (<±1°C) independently from the flow. The screw compressors provide a constant delivery pressure to the gas turbine fuel system independently fro the load and establish the fuel volume required. The volume handled by the system is regulated by a slide control system developed specifically for applications where a variable, bumpless flow control is required. The standa rd control system interface is based on the latest equipment technologies available on themarket and the screen configurations are tailored to each customer’s needs.

Per the customer’s request, the fuel package can be provided with a remote monitoring system that allows Enerproject to monitor the working conditions of the equipment directly from their Swiss headquarters. The company’s service personnel can intervene remotely or, if necessary, through local specialists available worldwide. The high reliability of their equipment and monitoring system, however, reduces unscheduled interventions to a minimum.

In addition to the fuel gas skid, Enerproject is available to supply its customers with a complete turnkey scope of supply, which may include a metering station, filtration system, pressure reducing station, supervision system and standard or tailored training of a customer’s personnel.

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