Study On Water Saving Optimization Of Thermal Power Plant Water System Based On Water Quantity And Quality Coordination

The rapid development of society and economy is inseparable from the rational development and utilization of water resources.In the new era of"water saving priority,space balance,system management,two-handed efforts"under the water control policy,water saving as the primary consideration of policy.China is a country dominated by thermal power generation,and the water demand of thermal power plants accounts for a large proportion in the whole industrial level,but the existing coal-fired power plant water problems such as low efficiency,severe water shortage,pollution,and studies on water saving and emissions reduction of thermal power plants to stay on the basic water intakes,use,consumption,such as the analysis of the accounting process,as well as water-saving theory on the analysis of concept and lack of deeper water saving study,does not meet the national water demand for higher power in society.Therefore,this paper carries out research with the purpose of saving water in thermal power plants,the specific research contents and results are as follows:(1)The theoretical basis of optimal allocation of water saving in thermal power plants based on water quantity and quality pooling is analyzed.Starting from the method of water resources system analysis,this paper analyzes the concept of the overall and optimal allocation of water quantity and quality,analyzes the structure and characteristics of the water system in thermal power plants,clarifying the water consumption and water-saving nodes in the process of water supply,use,consumption and discharge,as well as the requirements of each water system on water quantity and quality.It is found that it is reasonable to apply the overall allocation of water quantity and water quality to the optimal allocation of water saving in thermal power plant.(2)The construction and application of water saving optimal allocation model based on water quantity and quality.By analyzing the optimal allocation principle of water saving in thermal power plants,taking the minimum consumption of fresh water as the objective function,and taking the water balance of the water unit,the mass balance of pollutants in the process of water consumption,the maximum allowable pollutant inlet and outlet concentration and non-negative value of the unit as constraints,the water saving optimization model of the water system of thermal power plant with direct reuse of sewage was established.The single pollutant Cl~-is selected as the key pollutant according to the case of a thermal power plant,and the genetic algorithm is used to solve the problem.The results show that the fresh water consumption before optimization is3255.00m~3/h,and the fresh water consumption after optimization is 2967.94m~3/h,the optimization rate is 8.8%,and the annual water saving can reach 2,514,600 m~3.The displacement of water decreased from 364m~3/h to 76.95m~3/h,the optimization rate reached78.9%,and the reuse rate increased from 98.59%to 98.71%,which showed good economic and environmental benefits.(3)The water saving level of the example thermal power plant was evaluated.Firstly,11 representative evaluation indexes,such as the amount of water taken per unit product,the concentration ratio of circulating water,and the reuse rate,were selected.,the evaluation index system was constructed according to the target layer,the criterion layer and the scheme layer,and the analytic hierarchy process(AHP)was used to calculate the weight of the indicators at each level,among which the CR was all less than 0.1,meeting the consistency requirements;Secondly,the fuzzy comprehensive evaluation method(FCE)was used as the evaluation model.According to the actual data before and after optimization and the index base value,the membership function values were calculated by grading.Combined with the index weight,the membership matrix before and after optimization was obtained as(0.568,0.298,0.134)and(0.289,0.370,0.341),respectively.According to the principle of maximum membership degree,0.568 and 0.370 were selected as the membership grade interval before and after optimization;Finally,the evaluation and scoring method was used to compare and verify the results,which were0.79 before optimization and 0.86 after optimization.According to the classification standards and different evaluation methods,the water-saving levels of thermal power plants are all changed from non-water-saving enterprises to water-saving enterprises.The research on water-saving optimization of thermal power plants can not only relieve the water pressure of water resources in China,but also has important significance for thermal power plants to make more reasonable and efficient use of water resources,formulate strict water resources management measures and realize good social,economic and environmental benefits of power plants.