Study On The Growth Regularity And Control Of Microorganism Of The Cooling Water In Power Plant

Circulation cooling water is the main component of water consumption in a heat power plant, and it is also a prerequisite to assure an excellent operation. To improve circulated cooling water system is a key factor for water saving in a heat power plant, and the increase of economic benefit is related to water saving and the period of instrument servicing. Based on the real situation of operation technics and make-up water of circulated cooling water system in Taiyuan First heat power plant, microorganism in circulating cooling water and make-up water Jinyang Lake that studied in this thesis as an important research object was tested. The growth condition of the microorganism was completely and systemically examined and the growth regularity along with the control measures of microbe was also explored in details.Four major contents were involved in the current study: the growth and change regularity of microbes' breeds and amounts of circulated cooling water and make-up water in different seasons; index of ammonia nitrogen, nitrite nitrogen, liquefaction oxygen, chief iron, rigidity and conductance in summer; study on system superior bacteriostasis effect of different bactericide under different conditions; and control regularity on microbes' growth and propagation of several kinds of complex bactericide. Through the research, we hope to understand the microbial growth rule of the circulated cooling water system of power plant, and put forward the best project of bactericide usage and the most suitable bactericide prescription for circulated cooling water quality in combination with the real situation of production operation system, guarantee the secure running of power plant' recycling cooling water and make-up water system and save its running cost, making economic and environmental benefits for the plant. Meanwhile, the research is of significance of a reference for the microbial controlling technology of recycling cooling water system in other industries.The thesis consists of the following conclusions: 1,Growth regularity of microbe: heterotrophic bacteria was considered the main microbe in make-up water and recycling cooling water system. The amount of heterotrophic bacteria basically is 10³-10⁴ /ml in two water systems in spring, autumn and winter, higher than 10⁵/ml in summer, and the mount in recycling cooling water is much higher than that in make-up water system. Except for the summer, the amount of other microbes is lower than 10³/ml in other seasons. Compared with other seasons, the amount of microbe is the highest in summer, so more control methods should be intensified to the microbe during summer.2,Change regularity of microbe in separate sterilization test of three bactericides: sterilizing rate of oxidizing bactericide is low, which is not suitable for the make-up water system in power plant. The higher sterilizing rate of other two kinds of non-oxidizing bactericides can be shown after 36 hours. So during the real operation, the three bactericides are not suitable for single usage.3,Growth and change regularity of microbe during the add-drug period of complex description bactericide: the study chose 8 groups of complex bactericide descriptions, according to the control effect on the superior bacterium of cooling water system, came to the following conclusions:a) The above 8 groups of complex description bactericide have high sterilizing rate and rapid effect. The sterilizing rates equally are higher than 80% after 4 hours, 99.9% after 24 hours, lasting for 96 hours. Therefore, it is suggested that the adding drug period of 4 days is the most appropriate.b) The effects of complex description bactericide with low chroma of three types of bactericide are better than that of two combined bactericide. According to the dispatch analysis result, the interaction of three types of bactericide with two combined is weak, which consequently is inadvisable.c) The most economical prescription is chlorine 30mg/L + ketone 30mg/L + TH-406 10mg/L, which costs only 25000 Yuan one year, greatly lower than the present invest of Taiyuan First heat power plant.d) In order to prevent the drug-resistance of the microbe using the same bactericide for long time, it is suggested that the 8 groups of complex prescription bactericide are used alternately for one month period, thus the drug-resistance of the microbe can be reduced efficiently.4,The oxidizing bactericide CLO₂, used in the make-up water system of Taiyuan First heat power plant for a long time at present, brought bad usage effect, which lead to the growth of a great amount of microbes, and the jam of active carbon filter, and now is forced to be examined and repaired. Therefore, it is suggested that the above complex prescription bactericide can be used.