Ammonia compound concentration measuring device and ammonia compound concentration measuring method

An ammonia compound concentration measuring device which measures an ammonia compound concentration of a measurement subject contained in a circulating gas, the ammonia compound concentration measuring device comprising:

• a pipe unit through which the circulating gas flows;
• a converter which is disposed in the pipe unit and converts an ammonia compound contained in the circulating gas passing through the converter into ammonia;
• a measurement device which measures a first measurement value as a concentration of ammonia contained in a first circulating gas flowing inside a pipe line with the converter out of the circulating gas flowing inside the pipe unit, and measures a second measurement value as a concentration of ammonia contained in a second circulating gas flowing inside a pipe line without the converter out of the circulating gas flowing inside the pipe unit;
• a first flowmeter which is disposed at an upstream side in relation to the converter and measures a flow rate of the circulating gas flowing into the converter;
• and
• a second flowmeter which is disposed at a downstream side in relation to the converter and measures a flow rate of the circulating gas discharged from the converter;
• and
• a controller which controls operations of the pipe unit and the measurement device, and calculates the concentration of the ammonia compound contained in the circulating gas from a difference between the first measurement value and the second measurement value,
• wherein the measurement device includes
• a light emitting portion which outputs a laser beam having a wavelength absorbed by the ammonia and being in a near-infrared wavelength band,
• at least one measurement unit which includes a gas measurement cell causing the circulating gas to flow therethrough, an optical system causing the laser beam to be incident to the gas measurement cell, and a light receiving portion receiving the laser beam incident from the light emitting portion and passing through the gas measurement cell,
• a calculation portion which calculates the measurement value of the ammonia of the circulating gas flowing through the gas measurement cell based on an intensity of the laser beam output from the light emitting portion and an intensity of the laser beam received by the light receiving portion, and
• wherein the controller corrects and calculates a measurement value of the ammonia of the circulating gas based on a measurement result of the first flowmeter and a measurement result of the second flowmeter.