Calibration Free On-line Oxygen Measurement System Based On TDLAS

Fuel combustion,industrial production,transportation and other industries will produce gaseous pollutants such as sulfur dioxide,nitrogen dioxide and carbon monoxide.Oxygen as oxidant and oxidant,widely used in energy,metallurgy,chemical industry and other fields.To achieve real-time online monitoring of oxygen,can provide the basis for improving combustion efficiency and reduce pollutant emissions.Tunable diode laser absorption spectroscopy(TDLAS)technology with its high sensitivity,high resolution and non-contact measurement has become a powerful tool for gas parameter monitoring.The current based on the wavelength modulation spectroscopy technology in implementation are mainly in two ways:using the computer as the core of data processing,through the acquisition card or ADC transmission intensity signal acquisition module will be converted to the digital signal by digital phase-locked operation,then the iterative fitting of gas parameters;through the use of analog phase-locked extraction of signal harmonic,harmonic signal of analog lock-in amplifier output low ADC sampling,used to derive the gas parameters.In the first scheme,because using computer so it is bulky and not easy to carry.And the latter adopts analog method for extraction of the harmonic,which is easy to be affected by temperature drift,so the measurement accuracy is difficult to guarantee.In order to overcome the shortcomings of the two methods,this paper proposes a calibration free TDLAS oxygen measurement system,which take Altera’s field programmable gate array(FPGA)as the core data processing center.A detailed in-depth,introduction is presented from the system’s hardware structure and software realization of the system..1.Using the parallel computing characteristics of FPGA and combining digital signal processing technology,The whole system’s signal generation,data acquisition and data processing module are integrated together to realize the miniaturization of the system.2.According to the computing ability of embedded system is relatively poor gas parameter fitting algorithm based on series expansion is proposed,this algorithm can greatly reduce the computation time required and the consumption of FPGA hardware resources.And through the Quartus Ⅱ and MATLAB simulation,and implementation of specific work system,verify the feasibility of the algorithm.This research adopts FPGA as the core of data processing,combined with digital signal processing technology,the construction of TDLAS oxygen measurement system calibration free,to achieve real-time online monitoring of oxygen concentration parameters and integrated system for miniaturization,miniaturization of gas measuring system based on TDLAS technology,industrialization and provide reference.