Laser-based IR spectroscopy for measuring sulfur trioxide in the exhaust gas of gas power plants

The invention relates to a method for determining a sulfur trioxide content in a gas (1). A sample (2) of the gas (1) is taken, and a gas pressure of the sample (2) is reduced. A wave number-resolved transmission measurement is carried out on the sample (2) using a wave number-tunable monochrome light source (3), and a sulfur trioxide content is derived from the measurement. The measurement is carried out in the sulfur trioxide absorption band between 1360 and 1410 cm-1, in particular in a window around the sulfur trioxide absorption at 1365.49 cm-1. The invention further relates to a method for operating a power plant (7), to a measuring system (10) for determining a sulfur trioxide content in a gas (1), and to a power plant (7). 本发明涉及种用于确定气体(1)中的三氧化硫含量的方法，其中提取气体(1)的试样(2)，并且降低试样(2)的气压，并且波数可调谐的单色光源(3)对试样(2)执行波数分辨的透射率测量，并且根据测量推导出三氧化硫含量，其中测量在1360cm和1410cm之间的三氧化硫吸收带中、尤其在1365.49cm处的三氧化硫吸收附近的窗口中进行。本发明还涉及种用于运行发电厂设施(7)的方法。此外，本发明涉及种用于确定气体(1)中的三氧化硫含量的测量系统(10)和种发电厂设施(7)。