| The fast expansion of the industrial scale and the economic growth require the substantial development of energy productions and raw material supplies.However,their negative effects have also largely change the human living environment and ecology.Anthropogenic environmental pollutions and according ecological issues have been paid much attention now.In China,coal has been primary energy resource,and raw materials are mainly from minerals and supported by metallurgical industries.Both coal and minerals are multiple-element sources.Their utilizations unavoidably bring many hazards heavy metal elements and sulfur trioxide into the environment,harmful to human healthy and environment quality.Both of these two pollution sources are in trace amounts,but in the significant negative effects,comparing to other regular pollutants(SO2,NO and PM10).Trace metals,such as mercury,arsenic,selenium,lead,cadmium and chromium,are bio-toxic and accumulating in human bodies.These elements can make human organ function loss,resulting in poisoning,even death.Sulfur trioxide is corrosive and environmentally-damageable to the ecological environment,such as water pollution,soil pollution and so on.These two categories of pollutants in the trace amounts have been listed to be the future control target,after major regular air pollutants(SO2,NO and PM10)are under largely controlled.Effective emissions control demands accurate monitoring and analysis approaches.This is especially true for the analysis chemistry in the trace amount levels.In order to realize the monitoring and analysis of heavy metal elements and real-time monitoring of sulfur trioxide in flue gas,a integrated system with many sub-systems controlled by a LabVIEW software environment was designed.For the flue gas sampling,a set of flue gas sampling and conditioning sub-system was designed according to the US EPA method 29 to collect and convert targeted trace heavy elements and sulfur trioxide in flue gas to be ions of those metals and sulfuric acid.Determination of heavy metal elements was subject to the cold-vapor(Hg)and hydride generation(As,Se,Pb,Cr,Cd)prior to the atomic fluorescence spectrometry,which is highly sensitive,low in the detection limit and non-dispersive in their optical systems.The integration of cold-vapor and hydride techniques can help on eliminating most interference in elemental analysis and facility simultaneous multiple-element analysis.The molecular absorption spectroscopy was applied for the continuous on-line determination of sulfur trioxide,eliminating disadvantages of non-continuous methods such as gravimetric method,titration,atomic absorption spectrometry,spectrophotometry,etc.In order to better serve on the improvement of the work efficiency toward the applied atomic fluorescence and the molecular absorption spectroscopy.The 3D printing technology inspired the design of an autosampler setup,greatly improving the precise positioning and sample processing capacity.This thesis thorough documented designs,trail-to-errors and achievement of the overall analysis system of trace metals and sulfur trioxide with several sub-systems integrated by the single automation software environment.The specific details of those sub-systems are presented below.1.Cold-vapor and hydride generation-atomic fluorescence spectrometryThe overall atomic fluorescence spectrometry system consists of an excitation light source,an atomizer,an optical unit,a PMT detection unit,injection unit,gas-liquid separation unit.The atomic fluorescence spectrometry system achieved the analysis of mercury(Hg)in a linear correlation coefficient over 0.999 and the detection limit less than 0.5ng/mL(ppb).The current status of the hydride generation method successfully the simultaneous analsysis of As,Pb,Cd,Se,Cr in a linear correlation coefficient over 0.9.2.Molecular absorption spectrometryMolecular absorption spectrometry for sulfate analysis is mainly composed of an injection unit,a reaction unit,a light source and a CCD-based detection unit.This system is based on the reaction of barium tranexamate with the target sulfur trioxide to generate the purple chlororan acid ion(HC6O4Cl-),whihc can absorb the light wave at the wavelength of 530 nm and detected by the visible light spectrophotometry.The sulfate ion concentration is equivalent to the generated chlorotranate ion.This system featured excellent anti-interference ability against likely flue gas conpositions,such as halogen(chlorine and bromine)and other major regular acid gases(sulfur dioxide,nitrogen oxides and carbon dioxide)in conventional flue gas.The measurement range of target sulfur trioxide can range from 0.1 to 100 ppm(optional ranges in 0.1 to 20 ppm,or 20 to 100 ppm,)with the detection accuracy in 0.1 ppm.3.The flue gas sampling system and autosamplerThe Flue Gas Sampling System is a self-designed sub-system based on the requirement presented in the USEPA Method 29 for elemental flue gas collection and conditioning.It is mainly composed of a sampling gun,an absorption conditioning device and an control panel.It serves for both samplings of trace elements and sulfur trioxide in flue gas.An autosampler unit was designed to improve the work efficiency,in an event of one-time handling of over hundreds samples. |
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