Study On System For Real-time Corrected Type CO Analysis

In order to improve the combustion efficiency of coal in thermal power plant,coal block will be ground into pulverized coal by coal mill,and CO will be produced in the mill during grinding.In the process of grinding,if there is coal dust accumulation,the CO concentration and temperature will rise,when it rises to a certain extent,it may cause explosion.Therefore,the detection of CO concentration is particularly important in the safety production of power plants.At present,some domestic and foreign manufacturers have realized the CO concentration detection,but most of the CO measurement accuracy is low,detection sensitivity is not high,and the need for frequent replacement of sensors and other shortcomings.Also some foreign manufacturers can better test CO concentration,related CO detection instruments are more mature,but the cost is higher,not conducive to batch use,and the need to monitor manual timing.Therefore,this subject designed an on-line concentration detection system for carbon monoxide(CO)that can be modified in real time.The system design was elaborated from the aspects of general scheme,optical path,circuit,structure and software,etc.Finally,the experimental system was built and the standard gas was used for calibration and measurement.The system extracts the gas inside the coal mill to the gas chamber of the system for analysis and measurement by means of extraction,and the concentration test results can not only be routinely displayed and output,but also can be wireless remote transmission of measurement data through GPRS module.In this way,monitoring personnel do not need to go to the test site but also can monitor the data on the remote monitoring software,which not only ensures the security of monitoring,but also can give real-time alarm,greatly reducing the cost.The project is based on the principle of molecular absorption and Lambert Beer’s law as the theoretical basis,and the difference method as the detection model to design the system.The system uses dual CPU to control and drive each functional module,including transmitting module,receiving control module,communication module,display key module and power module.It is not only efficient,but also easy to build system equipment.At the same time,the system also designed a self-tuning detection method in the design process,that is,the gas chamber is divided into two parts,one part is used as the measuring gas chamber,the other part is sealed with the standard gas without CO,which is used as the reference zero adjustment chamber.This method avoids the error caused by the zero drift in the common detection method,and the measurement accuracy has been significantly improved.The system has completed the corresponding calibration test experiments with the purchased standard CO gas of different concentrations.The experimental results meet the accuracy requirements given by the thermal power plant,and the error is within 2% of the full scale.