Research On On-line Intelligent Measuring Instrument For Ethanol Concentration Based On AVR

Ethanol concentration is the important control parameter in microbial fermentationproduction. Quickly and safely testing ethanol concentration is one of the most importanttechnology of microbe engineering.The existing ethanol concentration measurementtechnology includes clearance sampling method, chemical titration method or electrolyticmethod and the method of off-line analysis, etc. The data in these test methods can only beused for roughly estimating the fermentation sampling state; Existing online testingtechnology has certain limitations. And the detection technology which is based on theprinciple of optical and acoustic can not rule out the error of measurement well caused by thechanges of other solute concentration. Additionally, it can only achieve ethanol concentrationmeasurement in binary solution of water and ethanol. Detection technology based on theprinciple of biological which has biological sensors itself will seriously pollute theenvironment of fermentation that it currently is not suited for testing the concentration ofethanol in the fermentation process. The detection technology based on gas sensitive effectuses sampler to sample detecting the concentration of ethanol on-line outside the fermenterand has a certain time delay. So it has not been realized for the true sense of the real-timedetection. Also, the sampling process has certain disturbances followed with lowprecision.Therefore making a research about the ethanol concentration of real-time onlinedetection technology in microorganism fermentation and developing an intelligent ethanolconcentration online detector has important practical value.This design is on the foundation of detailed analysis of ethanol concentration change inmicroorganism fermentation process, and is on the basis of the principle of ethanol throughfilm, gas sensitive effect and gas liquid equilibrium. It develops ethanol concentration on-linedetection technology, establishes intelligent online measurement model of ethanolconcentration based on least squares fitting and makes an intelligent ethanol concentrationonline detector. Semiconductor gas sensor (TGS822) is adopted in this detector to realizereal-time detection of the concentration of ethanol; it uses embedded technology with microcontroller (ATMEGA16) as the core of the embedded system and matches up a16highresolution ADC (AD7705) to achieve signal acquisition and analysis and processing of data;Through communication interface of the RS-485bus,it is joined with a PC, realizing theconcentration of ethanol on-line detection and intelligent monitoring in the process of thefermentation engineering.The experiment proved that the on-line measurement technology of ethanolconcentration can be reached by the principle of ethanol through film, gas sensitive effect and gas liquid equilibrium can realize the real-time online detection of concentration of ethanol inthe fermentation process. The corresponding relations between ethanol concentration basedon the least squares fitting and resistance tested by gas sensors are accurate and reliable;detector developed based on the above principle can be used in detection of ethanolconcentration of multiply mixture of fermentation liquor with high precision and can makevarious design functions about ethanol concentration on-line detection,which is better tosatisfy the requirements of the process of automated production in microorganismfermentation.