GAS ANALYSIS DEVICE, CONTROL SYSTEM AND CONTROL ASSISTANCE SYSTEM FOR COMBUSTION FACILITY, AND GAS ANALYSIS METHOD

A gas analysis device includes: a measurement part configured to measure an absorption amount of a laser light including an absorption wavelength corresponding to at least two electronic level transitions having the same component contained in the combustion gas, by emitting the laser light on a plurality of measurement paths disposed to pass through the combustion gas; a standard setting part configured to set a standard gas concentration distribution and a standard temperature distribution on the basis of a measurement result of the measurement part; and an analysis part configured to obtain the gas concentration distribution and the temperature distribution by solving a function including the gas concentration distribution and the temperature distribution as variables so as to minimize a difference between the absorption amount measured by the measurement part and a standard absorption amount obtained on the basis of the standard gas concentration distribution and the standard temperature distribution.