| Under the background of ultra-low emission in China,the tail gas of coal-fired power plants is characterized by low concentration and high humidity under the policy guidance.Existing smoke analyzers are generally subject to dust and vapor interference,zero point and range under the background of ultra-low emission.With the common problems such as large drift,high detection limit,poor environmental adaptability,etc.,in order to achieve accurate monitoring of emissions from fixed sources under ultra-low emissions,this paper uses the DOAS method to simulate the characteristics of ambient temperature changes in the actual operating conditions of the flue gas analyzers and the absorption spectra of SO2 and NOx at different temperatures and pressures.The gas concentration was inspected using the absorption cross section of the gas under different temperature and pressure.Compared with the actual concentration,polynomial fitting and exponential fitting were used for the two sets of data.The error was from 30%to 56%of the original,and the compensation function was used.The concentration error after fitting is within 1%.To solve the problem of poor linearity of the gas analyzer when the concentration of the gas to be measured is high or low,the spectral characteristics of the gas at low concentration and high concentration are measured at equal intervals in the range of 0-500 ppm on the basis of 250 ppm.Non-linear fitting,after the non-linear compensation of the data obtained by polynomial and exponential fitting,the error reduced from up to 8%to less than 1%.A spectrometer on-line calibration method is developed based on the SO2 characteristic absorption band reference point for spectrometers that are prone to wavelength drift under different operating conditions.This method is easy to operate,low cost,and can be used to calibrate the wavelength drift of spectrometers.After the wavelength is calibrated quickly,the wavelength drift is reduced by 97.7%in the two absorption bands 202-214nm and 280-31Onm.The temperature drift 10? reduces the drift of the flue gas analyzer by 98%,and the measurement error can be controlled within 2%.Greatly improves the stability and measurement accuracy of the flue gas analyzer.Subsequently,the laboratory test and field tester of the monitoring instrument ASP-3000 formed based on the above-mentioned research was conducted to examine the scientificity and feasibility of the above research.The zero point of the ASP-3000 under different conditions of temperature,humidity,and vibration was tested under laboratory conditions.Measurements of range and indication errors were conducted to examine the environmental adaptability of the instrument.Subsequently,they were used at four sites:Guodian Changzhou Power Generation Co.,Guodian Power Generation Co.,Ltd.,Yangzi Petrochemical Co.,Ltd.Thermal Power Plant,and Tianjin Guodian Jinneng Binhai Thermal Power Co.,Ltd.ASP-3000 portable smoke analyzer is used for demonstration to examine the universality of ASP-3000.Laboratory tests show that ASP-3000 indicators are superior to national standards and are superior to most products on the market.They have a temperature change of 40? and a humidity change of 43%.Under vertical half-wave vibration,SO2 and NO gases are the maximum values of the zero point change were-1.1%FS and-0.4%FS,respectively.The maximum values of the span change were 1.4%FS and 1.7%FS,respectively.The maximum changes in the indication error were 2.8%and 1.3%,respectively.The maximum deviation of the SO2 concentration from 0 to 7.00ppm is-0.102ppm,the NO concentration is from 0 to 14.94ppm,and the maximum deviation from the measured value is-0.254ppm.The zero-drift and range-shift parameters of ASP-3000 are far below the national standards under different operating conditions.The laboratory test and field test application demonstration results show that ASP-3000 has good environmental adaptability and can be applied to all kinds of harsh measurement conditions.It also further demonstrated the scientific nature of the aforementioned compensation model. |
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