Study On System For Extracted Type Ammonia Analysis

At present,the public and society pay close attention to the problem has changed from economic development to ecological environment.As a developing country,China still uses coal as the main energy source,such as electricity.According to statistics,domestic thermal power generation still accounts for 73%of the total power generation in 2018.Therefore,the emission control of coal-fired plants is still an important part of environmental protection.In coal-fired plants,ammonia gas is used as reducing agent in off-sale reaction,and excessive input ammonia escapes into the atmosphere to form pollution.According to the national standard,the escape ammonia concentration is limited to 20 ppm,which requires the measurement accuracy of the system,and because of the bad flue environment,high temperature and dust,the system installation and filtration effect has higher requirements.Combined with the market and field working conditions,this paper takes Lambert-Bill’s law and TDLAS technology as the basic measurement principle,and develops a set of extraction ammonia gas on-line detection system on the basis of existing technology at home and abroad.Distributed feedback laser is used as the light source,and a set of angular cone prism systems are used to meet the needs of optical path.The prototype can measure 10 ppm ammonia gas in practice and meet the design requirements linearly.This thesis is mainly divided into four parts:optical principle,optical design,structural design and prototype experiment.The optical principle part is mainly the optical principle analysis of this subject;the optical design part is mainly the selection and setting of optical components and parameters;the structure design part is mainly the system gas path design,It also includes the selection of important components in pneumatic part.