High-voltage Pulse Sterilization System For Industrial Circulating Cooling Water

Circulating cooling water system is the essential equipment for heat transfer of large-scale installations in industrial production. The important factors which interfere with the normal operation of the system are incrustation and corrosion. Especially in the industrial circulating cooling water systems, there is good condition for microorganisms'growth and reproduction, so it is easy to breed bacteria and algae. The metabolites, which generated in the microorganisms'lives, can combine with the various salt ions in circulating cooling water, and the compounds result in the corrosion of pipes and the damage of device. Therefore, the incrustation and corrosion caused by microorganisms are one of the main factors that cut down the heat transfer efficiency and life of heat exchange equipment in circulating cooling water system.At present, sterilization by the high-voltage pulses has been widely applied as a newly-type non-thermal treatment technology, and its mechanism is that high-intensity pulsed electric field can destruct the microbial cell membrane instantaneously and lead to the microorganisms'death at last. In order to get rid of harm caused by biological mud which is generated from the waste of microorganisms'life cycle and water impurities in circulating cooling water system, a set of high-voltage pulse sterilization equipment based on the Marx circuit, and a miniature simulation cycle water system are developed. Simultaneously, simulation and analysis on the distribution of electric field in the internal of cavity are completed with electromagnetic field simulation software (Maxwell from Ansoft Corporation). Eventually, this high-voltage pulse system is applied to do sterilization experiments. The main research works are listed as follows:①Based on the references at home and abroad, the sterilization mechanism of high-voltage pulse was analyzed and synthesized, which was made up of three parts: liquid discharge mechanism, the destruction of water molecules, and the destruction of the cell membrane.②A high-voltage pulse generating device based on Marx generator was developed. The single chip control system is applied to adjust the pulse voltage and pulse frequency, and communicate with host computer. Then, analysis and calculation of the charge and discharge circuit model and each component parameter of circuit are completed.③The structure of high-voltage treatment chamber was designed by Ansoft Maxwell software. Comparison and analysis of the electric field distribution among needle electrode treatment chamber, plate electrode treatment chamber and coaxial electrode treatment chamber are done, so as to settle down the most suitable treatment chamber.④The high-voltage pulse sterilization experiments were carried out with self-made circulating water mini-system. The viable bacterium after high-voltage pulse stimulation was counted by standard plate count method, and the effect of high-voltage pulse sterilization was quantitatively analyzed. The damaging effect of bacterial DNA after high-voltage pulse treatment was detected by agarose gel electrophoresis, and the effect of high-voltage pulse sterilization was qualitatively analyzed.