The Shandong Shiliquan Zero-emission Power Plant Wastewater Study

With the serious lack of the water resources, the suitable treatment of wastewater in the power plants not only can save water, but also was very important to the safe and economical operation of the thermal power plants. In our country, the operation of the most power plants was in the low circulating ratio and in the low ash-water ratio. So the quality and quantity of the water and wastewater in power plants were determined by the cooling water circulatory system and the ash-sluicing system. The characteristics of the water and wastewater in power plants were investigated in this paper, and zero discharge system was designed according to our country's condition. At the same time, the optimum ways of calculating the circulating ratio were also put forward. Zero discharge process included improving the cooling water system by increasing the concentrate ratio and decreasing drain, and ameliorating the ash-sluicing system by closed-circuit and supplying water with the wastewater. So the consumption of water and wastewater were reduced in the power plants.Shandong Shiliquan power plant was an old factory with more than 20 years' history, which had totally seven units. Its water resource was running short. Taking Shiliquan power plant as example, the Zero discharge system was researched. First the characteristics of water and wastewater in the Shandong Shiliquan power plant were investigated. Then Zero discharge system was designed base on the result of the investigation.The concentrate ratio must be heightened when Zero discharge system was in practice. But the investigation indicated that the corrosion of equipment in cooling tower was the most serious problem after increasing the concentrate ratio. The processing of the circulating cooling water was investigated, and the corrosion and furring mechanism was discussed. According to the statistic data, the investigation of water quality and Langlier judgment, the treatment method of the circulating cooling water was confirmed. The operating and controlling scheme for the circulating cooling water are established, according to the actual operation conditions of the plant. In the ash-sluicing system, the draining water of upper level was mainly used as the supply water to sluice ash. So thesupplement and consumption of water were reduced. At the same time, through adjusting the water quality, the corrosion and scale of the ash-sluicing system was prevented.Improving the cooling water system and the ash-sluicing system is the key of implementing Zero discharge system of the wastewater in the power plants. Zero discharge system of the wastewater was a relative complex systems engineering. It is only a pilot study was carried out in this paper under the existing technical situations.