Continuous Measurement Of Soot Concentration In The Exhaust Duct

Circumstance Protection is the basic national policy of our country, and the soot particles concentration is the most important influencing parameter to circumstance protection. Now there are many soot particles concentration measurements and metrical system based on different principles, which have offered impelling means to the tests of soot measurements. But the measurements widely used at present have many disadvantages such as the low creditability of metrical results, long metrical periods, being incapable of fulfilling on-line, continuous measurements. Along with the deeply research of gas-solid flow and the increasing demands for accurate measurements and industrial control, it is imperative under the situation to develop the continuous measurements of soot particles concentration. Besides these, more and more industrial situations require the non-disturbing measurements. With the technical development of laser light, light fine and computers, light dispersion, as one kind of important on-line, non-disturbing measurements, has been increasingly regarded due to its speediness, high distinguish rate and great info.A novel on-line method of measuring the soot particles concentration, which is applied the integral transform inverse arithmetic based on Fraunhofer's diffraction theory and the mean theory, is developed in this paper. Compared with the Extinction techniques, new technique is not pre-required knowledge of size of particles in the flow.Author researches and develops a novel laser light on-line supervisory system of measuring the soot particles concentration. By measuring the laser light signal of flue in real time, and using the single chip and computer to deal with the sample data to fulfill the on-line soot particles concentration measurement.Demarcation is the most important part of measurement, the metrical system's accuracy is greatly related to the demarcation. The supervisory system in this paper has on-line Demarcation operation.The Main contents of the paper are as follows:Actuality of the soot particles concentration measurements in our country:The measurements widely used can be divided into two parts: off-line measurements and on-line measurements. Off-line measurements, such as Ringelmann, forecast velocity of flow, reflect the instantaneous or short time emission status of contamination, are used to supervise the emission source and to appraise the accuracy of the continuous metrical system. On-line measurements, such as triboelectricity, extinction, radial, are used for long-term, continuous supervisal, which can reflect the real-time emission status of contamination.The research of on-line method of measuring the soot particles concentration based on the mean theory:Base on the basic principle of extinction, when measuring the ratio of the transmission light intensity and incidence light intensity is called permeation ratio. We must know the particles' average extinction coefficient and the average particle diameter to get the particles' concentration. In many occasions the average extinction coefficient is equal to 2,while based on the mean theory and the Fraunhofer diffraction, we can achieve a new method that is not pre-required knowledge of size of particles in the flow. The constitution of Laser light on-line supervisory system of measuring the soot particles concentration:Author designs the soot particles concentration supervisory system, which includes optic sub-system, single-chip pre-deal sub-system (includes 8031 μPU,A/D,D/A and so on) and data processing control sub-system.(developed by Delphi and Access2000) The whole supervisory system can supervise the soot particles concentration in flue on-line, and provide the functions such as data-saving, data-querying, curve-protracting, reports-printing. What's more, system can also process on-line demarcation, which will ensure the accuracy of soot particles concentration.