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Dry Low Emission (abbreviation DLE) is a technology that reduces NOx emissions that exhausts out of gas fired turbines .〔〔〔〔 The amount of NOx produced depends on the combustion temperature.〔 When the combustion takes place at a lower temperature the NOx emissions are reduced.〔 Gas turbines with DLE technology were developed to achieve lower emissions without using water or steam to reduce combustion temperature (Wet Low Emission (WLE) technology).〔〔 WLE technology demands cleaning of large amounts of water, is heavy, takes more space and can be difficult to install offshore.〔 A DLE combustor uses the principle of lean premixed combustion, and is similar to the SAC combustor with some exceptions.〔〔 A DLE combustor takes up more space than a SAC turbine and if the turbine is changed it can not be connected directly to existing equipment without considerable changes in the positioning of the equipment.〔 The SAC turbine has one single concentric ring where the DLE turbine has two or three rings with premixers depending on gas turbine type.〔 DLE technology demands an advanced control system with a large number of burners.〔〔〔 DLE results in lower NOx emissions because the process is run with less fuel and air, the temperature is lower and combustion takes place at a lower temperature.〔〔〔〔〔 ==Background for the technology== Increased focus on environmental issues led to increased research on new and better gas turbines with water and steam cooling methods in the middle of the 1970s.〔〔 The best technology could in 1980 reduce NOx emissions to 42 ppm and this was later reduced to 25 ppm.〔 In the 1990s ammonium and catalysators was tested and late in the 1980s the turbine producers started to develop «Dry Low Emission-technology» (DLE) to be able to get around the technology that demanded water or steam injection.〔 During the next ten years the DLE technology was developed and installed in many places leading to a reduction of NOx emissions less than 25 ppm.〔〔 It is difficult to achieve less than 9 ppm NOx emissions with DLE turbines.〔 To achieve a reduction from 25 ppm to 9 ppm more than 6 percent air must pass thorough the premixer.〔 Newer generations DLE burners has an extra injection leading to better control.〔 Additional systems like ”Selective Catalytic Reduction” (SCR) is necessary to achieve emissions lower than 2,5 ppm.〔 Technologies using water or steam (Wet Low Emission (WLE) can achieve approximately the same level of NOx emissions (25-42 ppm) when they lower the combustion temperature.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Dry Low Emission」の詳細全文を読む スポンサード リンク
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