Research On The Impact Of Neritic Power Plant Cooling Water In Yangtze River Through Numerical Simulation

In order to meet the needs of the residents for electricity utilization and release the power shortage, more and more large power plants were built. Therefore, the amount of cooling water was also increased. Cooling water from power plant contains a large amount of heat. After flowing into receiving water, it will make the temperature of river be higher than the natural water in a range of area by mixing and diffusion, which has created serious environmental problems on the surrounding area.This paper took the Yangtze River Luohuang river waters as the research object and established the mathematical model of Luohuang Power Plant cooling water. Under the normal(select August and September as the representative month, cooling water of 29.6 ° C) and abnormal working condition(select cooling water of 40 ° C), flow field and water temperature distribution of power plant cooling water emissions were imitated and analyzed. The validation was conducted by comparing the model error of simulation predicted values and actual values., The influence range and influence distance of the temperature were established through analyzing the model result. Furthermore, the suggestions to the cooling water emissions of Luohuang Power Plant and environmental protection were put forward, combined with ecological environment factors around the cooling water of Luohuang Power Plant.The research results were as follows:1. Under normal conditions, the main temperature range of the power plant cooling water in August and September was more than 1 ° C. This increased temperature was mainly concentrated in the downstream 200 m along the discharge outlet; and under abnormal condition, it is mainly concentrated in the downstream 500 m and 580 m along the discharge outlet.2. Based on the simulation results of flow field and temperature rise and the related equation of dissolved oxygen and water temperature,it shows: under normal conditions, the cooling water of power plant mixed with river water in the discharge outlet downstream, and the temperature of river gradually dropped to the background temperature of Yangtze river, and has no impact on the dissolved oxygen of the discharge outlet downstream; Under abnormal conditions, the dissolved oxygen concentration of the river reduced from 7.692 mg/L to 7.396 mg/L in August, and thus 0.296 mg/L of dissolved oxygen was reduced. In September, the dissolved oxygen concentration of the river reduced from 8.044 mg/L to 7.853 mg/L, and thus reduced 0.191 mg/L of dissolved oxygen. Therefore, under abnormal conditions, the influence of the cooling water was more serious to the plankton and fish in August.3. Under abnormal conditions, when the water temperature was more than 3 ° C in August, the influence lengthwas 230 m and the influence range was 0.070 km2. In September, the influence length was 276 m and the influence range was 0.068 km2. As can be seen from the two simulation results, under abnormal conditions, the excessive scope was bigger, and it has a certain negative influence the growth of plankton and fish to the region.