Design Of On-line Monitoring System Of Smoke Particle Concentration And Its Key Components Based On Gravimetric

With the rapid development of industry,environmental pollution has become increasingly serious,and research on energy-saving and environmental protection equipment has also received increasing attention.In particular,the monitoring of air quality is a top priority.On the basis of membrane weighting method,this paper proposes an on-line monitoring system for smoke particle concentration based on the method of micro-oscillation balance for the deficiency in the monitoring of smoke particle concentration in China.The group has developed a set of corresponding system prototypes and has been field-tested to prove that the prototype can realize continuous on-line monitoring of ultra-low emission smoke particle concentration,with high measurement accuracy and easy maintenance.The main work and innovations of the dissertation are as follows:(1)An on-line monitoring system for smoke particle concentration based on the method of micro-oscillation balance was proposed and designed to realize continuous on-line monitoring of the collection of flue gas and other flow rates and the weighing of particulate matter,which made up for the low degree of automation of the traditional weighing method.(2)An in-situ heated sampling gun was designed for the on-site environment.The in-situ heating sampling gun heats and controls the sampling sample gas in the sampling gun to ensure that the moisture and hydrocarbon compounds in the smoke with a relatively high humidity vaporize sufficiently,and at the same time avoiding the sampling outside the flue,due to the inside and outside of the flue The condensation of moisture in the sample gas caused by a large temperature difference affects the measurement.(3)An experimental comparative analysis of the shape and material selection of the oscillating elements of the oscillating balance was conducted,and a high-quality oscillating element was finally determined to ensure the measurement accuracy.(4)An on-line weighing device for automatic sampling and weighing was designed.Through the exquisite mechanical structure design,the oscillating balance and the on-line weighing device were well combined,and the automatic picking and replacement of the filter membrane was realized at the same time.The degree of automation of the entire system was increased.(5)A closed-loop self-excited oscillation drive circuit is designed for the vibration characteristics of the oscillating balance oscillating system,which realizes the self-oscillation of the oscillating system and provides the measurement basis for the oscillating balance.At the same time,the measurement accuracy and sensitivity of the oscillating balance were tested and the test results were analyzed.(6)An oxygen content detection unit was designed based on a zirconia oxygen sensor.For zirconia oxygen sensor of measuring oxygen characteristics,the sensor temperature compensation and control circuit,the oxygen concentration potential detection circuit and other control circuits were designed.The oxygen content detection unit is suitable for firepower plants and other harsh industrial environments,has a certain practical value.Finally,the designed flue gas particle concentration monitoring system was tested and operated in the thermal power plant,and the test data was compared with the monitoring data of the German Durage environmental monitoring instrument,and the possible causes of the measurement error were summarized and analyzed.Because the smoke particle concentration on-line monitoring system designed in this paper is based on the gravimetric method and realizes high-automatic continuous online monitoring,the structure is simple and easy to maintain,and the measurement accuracy is high,so it has a good market prospect.