(Radolfzell/Germany) Allweiler AG, a Colfax business unit, will deliver fuel-injection skids through Siemens AG for use in gas turbines in Iraq. The first two systems will be completed in early 2011. The Iraqi Ministry of Electricity has ordered an additional five skids and has options to purchase three more. All of the systems have the special ability to switch between several different liquid fuels without shutting down the turbines. They will be integrated into expanded power plants in Kirkuk as well as new plants that will be constructed in Baiji and Baghdad.
These fuel injection skids are designed for redundancy with two highpressure pumps. The gas turbines can be operated with 'EL' fuel oil and 'S' heavy oil or 'EL' fuel oil and crude oil. Switching between the various fuels is completed within approximately two minutes while the turbines continue to run. 'This was the biggest technical challenge in the development of these skids. But our solution to this requirement gave us the edge we needed to win the contract,' according to Stefan Kleinmann, Vice-President of the Industry business segment and member of the management boar d at Allweiler AG. Allweiler AG is a systems supplier with special expertise in power plant engineering, including decades of experience and highly specialized know-how in this field.
When switching between fuels, the system must withstand temperature differences of more than 120 °C without interruption. Johann Engelmann, Director of Sales and Service, offers his perspective: 'When the turbine is started, we're pumping low-viscosity fuel oil within a temperature range of 5 to 25 °C, but during normal and continuous operation the system is moving higher-viscosity crude and heavy oil at temperatures up to 130 °C. The temperature change is on the order of 60 °C per minute.' As a result, the system must have the ability to compensate for temperaturerelated changes. Precise control of liquid pressure before and after the pumps is critical for proper operation. If pressure decreases during the fuel changeover, gas bubbles will form in the liquid and may result in severe damage to the pumps and emergency shutdown of the turbines. Highly-refined valve control with fast reaction times can prevent this from occurring.
The pumps used in the system produce 287 kW of drive power; discharge pressure is approximately 100 bar at a liquid temperature of 130 °C.