Establishment Of On-line Monitoring Method For Water Treatment Agent And Design Of The Corresponding Instrument

There are mainly three problems in industrial circulating water systems,namely, scaling,corrosion and microorganism growth.In order to reduce those problems,a lot of different types of water treatment agents have been developed,such as scale inhibitors,corrosion inhibitors and flocculants.Nowadays,although water treatment agents produced at home and abroad can basically control the problems existing in the circulating water,it is still a key point to keep a proper concentration of effective agents in the circulating water system.Therefore,it is very important to determine the concentration of water treatment agents rapidly and accurately.This work was aimed to on-line monitor the water treatment agents.The main experiments and results are as follows:(1) According to the field operation parameters of a clean circulating water system in a selected steel plant,a technical route of the on-line monitoring for water treatment agents had been designed.The water treatment agents and a fluorescence tracer agent was mixed in proportion and put into circulating water system,and the fluorescence tracer was monitored on-line,and finally the concentration of the water treatment agents was calculated on the basis of fluorescence tracer concentration.(2) Carboxysulpho naphthalimide(CSN) was chosen as the fluorescence tracer agent.Its toxicity on zebra fish was tested.The result showed that there was no visible effect on the fish when CSN concentration was as high as 500 ng/mL under the explosure time of 96 h.Based on the water quality indexes of the circulating cooling water system in the steel plant,the effects of the temperature,pH,biocides and other parameters on the CSN fluorescence intensity were investigated.The results showed that CSN was stable to most of water conditions,but the high level of biocides could reduce the CSN fluorescence intensity.It was concluded that CSN could be used as the fluorescence tracer agent in circulating cooling water system.(3) A special on-line fluorescence monitoring system had been designed based on the modern analytical instrumental design ideas,such as integration, customization and miniaturization.Components of the designed fluorometer included the following parts:power source module,excitation source module, flow cell,optical signal filtering and focusing device,detector,data analysis and processing device,result displayer.(4) The stability of the on-line fluorescence monitoring system,and some performance parameters of the monitoring method,such as precision and detection limit,had been studied.The results showed that the performances of the instrument met the design requirements.(5) This on-line fluorescence monitoring method was an indirect method to determine water treatment agent,the feasibility of the method had been preliminarily proven with a dyanmic simulant device.It was found that there was a good correlation between the concentration of fluorescence tracer and total phosphates,if the concentration multiple of the circulating cooling water was less than 2.5.Therefore,using the mixture of CSN and water treatment agents in a proper proportion,together with the on-line fluorescence monitoring system,the on-line indirectly determination of the concentration of water treatment agents in low concentration multiple of clean circulating water system in steel plant could be realized.