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- Blomstedt, Mats, et al.
(författare)
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Innovative starting procedure of Siemens SGT-600 in cold climate conditions
- 2011
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Ingår i: ASME 2011 Turbo Expo:Turbine Technical Conference and Exposition. - : The American Society of Mechanical Engineers (ASME). - 9780791854648 ; , s. 1021-1026
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Konferensbidrag (refereegranskat)abstract
- A start-up of a gas turbine means that stress and forces are put on the machine. A start-up in cold climate conditions means that the forces are more critical since the material in the machine becomes more brittle. At a certain temperature the material is utilized to its limits (with appropriate margins applied) and for the SGT-600 ambient temperatures below -30°C (-22°F) become critical. In earlier installations in an arctic climate, an electric pre- heater has been utilized to prevent the critical components from becoming too brittle. This additional hardware costs money, is consuming auxiliary power and may contribute to unavailability. Another way to solve this issue may be to install material that is less brittle, but this will also increase the cost of the installation. Siemens is now applying an improved control logic during start-up, solving this issue in the software, without any additional hardware and avoiding unnecessary material changes. This new innovative start-up procedure is performing an automatic check of the stress levels before loading the machine, resulting in a safe and reliable start at temperatures below -30°C (-22°F).
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| 2. |
- Sammak, Majed, et al.
(författare)
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Conceptual Design Of A Mid-Sized Semi-Closed Oxy-Fuel Combustion Combined Cycle
- 2011
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Ingår i: Proceedings of the ASME Turbo Expo 2011: Power for Land, Sea and Air, 2011, Vancouver, Canada. ; 4, s. 253-261
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Konferensbidrag (refereegranskat)abstract
- This paper presents the study of a mid-sized semi-closed oxy-fuel combustion combined cycle (SCOC-CC) with net power output around 108 MW. The paper describes not only the power balance and the performance of the SCOC-CC, but also the conceptual design of the SCOC turbine and compressor. A model has been built in the commercial heat and mass balance code IPSEpro to estimate the efficiency of semi-closed dual-pressure oxy-fuel combustion combined cycle using natural gas as a fuel. In order to obtain the real physical properties of the working fluids in IPSEpro, the code was linked to the NIST Reference Fluid Thermodynamic and Transport Properties Database (REFPROP).The oxy-fuel turbine was modeled with the in-house Lund University package LUAX-T. Important features such as stage loading, loss modeling, cooling and geometric features were included to generate more accurate results. The oxy-fuel compressor has been modeled using a Chalmers university in-house tool for conceptual design of axial compressors. The conceptual design of the SCOC-CC process has a net efficiency of 47 %. The air separation unit and CO2 compression reduce the cycle efficiency by 10 and 2 percentage points, respectively.A single-shaft configuration was selected for the gas turbine simplicity. The rotational speed chosen was 5200 rpm and the turbine was designed with four stages. All stage preliminary design parameters are within ranges of established industrial axial turbine design limits. The main issue is the turbine exit Mach number; the stage must be lightly loaded in terms of pressure ratio to maintain the exit Mach number below 0.6. The compressor is designed with 18 stages. The current value of the product of the annulus area and the blade rotational speed squared (AN2) was calculated and found to be 40*10^6.
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