| Since the 1960s,people have realized the problems of Water shortage,water pollution as well as series of questions brought by it,the water treatment industry as an emerging profession obtain the considerable development.Embarked on the brand-new idea of analytic instruments intellectualization design,using microcontrollers as the core,depended on the technology of water analytic sensors, the present thesis has developed the intellectualized multi-parameters water quality online analytic system,which could reduce the water treatment industry's energy consumption and provides a kind of reasonable effective solution to guarantee water quality standards.In structure,the system divides into two parts:the water quality metering circuit and the data analytic procedure on PC.The water quality metering circuit is an independent automated test system,and the data analytic program on PC based on WINDOWS platform,can transform the data,sent by the water quality analytic machine,and carry on the further analysis,for example the graph demonstration,the data storage,printings and so on.The system circuit design is based on high performance-to-price ratio microcontroller C8051F021.The independent time sharing data acquisition of the temperature,the millivolt,the pH value and the conductivity is carried by the integrated 12-bits analog-digital conversion subsystem.The reference voltage is provided using the internal band gap reference.The amplifying circuit widely uses integrated difference operational amplifier AD620 to simplify the hardware circuit structure,obtain the high common mode rejection ratio and increase the measuring accuracy effectively;System's man-machine interface circuit is constituted by a resolution 128×64 liquid-crystal display and six independent keys.The water quality metering circuit and the data analytic procedure on PC communicate through the USB way,realizing plug and play.Delphi7.0 is used as the development environment of the data analytic procedure on PC.Microsoft Corporation's Access2000 is used to construct the backstage databases.The water quality metering circuit programming adopts the modular method,including:functional module driver design,various water quality parameters measurement routine design as well as man-machine interface design.The method of digital filtering,the bubbling law and the Wright criterion is carried out in the data algorithm,and different survey parameters mathematical models are established.Comparing with the former water analytic instruments,this system has the following merits:1.Multi-parameters analysis.Has realized analysis of the water temperature, the pH value,the Oxidation-Reduction Potential,the conductivity,the Total Dissolved Solids(TDS) and the salinity.2.Highly effective and stable metering circuit.On account of using microcontroller C8051F021,the drift error and errors are possible to eliminate through the procedure due to gain variation and disturbance and the hardware circuit is simplified using the massive specific IC.3.The function perfect data analytic procedure on PC.4.It has realized the water quality online analysis,which can be used as the attachment of process control device of industrial water.5.The USB communication,plug and play.6.High accuracy and low cost.Temperature measuring range form 0℃--100℃,relative deviation is 4.26%,the average relative deviation is smaller than 1.90%;Oxidation-Reduction Potential measuring range of-850 move--+850mv,the maximum absolute value of survey absolute error is 2.00mv,the average deviation is smaller than 0.8 me;pH value survey's scope is 0-14,the maximum absolute value of absolute error is 0.06, relative average deviation is in 0.44%;The scope of conductivity is 1μs/cm-20000μs/cm,the maximum absolute value of survey absolute error is 346.28/μs/cm,the relative average deviation is in 2.4%; The scope of Total Dissolved Solids(TDS) is 0ppm-20000ppm,the precision is up to the standard.The scope of salinity is 0.01-42.00,the precision is up to the standard..In the present thesis,the system designed of the multi-parameters water quality online analytic system and the experimental verification provided a reference for the development of electrochemistry class intelligence analytic instrument.The water quality analytic system can carry out online analysis of physical and chemical targets, satisfies the request of the water quality appraisal to some extent,provides a kind of effective solution for the water quality appraisal of the production and domestic water, and has certain practical significances. |
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