Numerical Simulation On Temperature Of River Under The Influence Of Thermal Power Plant Drainage

The energy requirement has been increasing with the continuous development of the economy of our country,the installed capacity of the thermal power generating unit augmenting increasingly.The waste water used for cooling power plant generator sets brings a large amount of heat into the receiving water.In addition to atmospheric diffusion,heat also diffuses in the water and mixes with the water of river,causing the local temperature of the receiving water to rise.First of all,temperature changes will inevitably change their water quality and ecology for natural rivers and will also have an impact on aquatic organisms.Secondly,if the water intake and outlet are not properly arranged,the discharge will reduce the efficiency of the unit and even threaten the safety of the power plant.Therefore,the accurate prediction of the thermal and thermal effects of power plant drainage is the basis for rationally designing the drainage outlets.It is also an important guarantee for rational environmental assessment.The main principle of the setting scheme of the power outlet of the power plant is to choose an economically viable way to reduce the influence of the temperature rise caused by the drainage of the power plant.Drainage arrangement includes the following factors: location of intake and outlet,drainage mode and structural form,etc.The problem to be solved in planning and designing the drainage scheme can be attributed to simulating the influence of temperature rise and determining the optimal engineering layout.This paper takes a power plant in Jiangxi Province as the research object,selecting a suitable hydrodynamic model,establishing a three-dimensional temperature diffusion mathematical model.The model was verified using similar engineering data.The temperature diffusion of three different outfall location schemes under different seasonal characteristic flows has been calculated with different outlet angles.Through analyzing the distribution of river the surface temperature rise,typical profile and typical vertical temperature rise distribution under various operating conditions,the layout scheme of drain outlet is optimized through comparison to provide reference for power plant drainage design.The main results of this study are as follows:1)After the future operation of the research project,the change value and range of flow velocity after the implementation of the proposed project will be the largest in autumn.The maximum value of the flow velocity increase in the local area near the project is 0.25m/s,and the flow rate increase is 0.05m/s.The influence range is about 975 m downstream and 420 m in the lateral width.The flow velocity of the surface water near the drain is large,and the lateral flow velocity is small.Generally speaking,warm drainage has little influence on the flow movement of rivers.2)Under a given drainage angle,the temperature rise range at the same drain location is affected by the runoff flow of the river,and the diffusion length along the warm drainage side and the diffusion width from the river bank are different.When the river flow is small,the temperature rise range of warm drainage reaches the maximum.The temperature distribution near the outfall diffuses violently along the longitudinal and transverse directions.When the river discharge is large,the temperature rise range of drainage is small.The waters near the drainage outlet are mainly laterally diffused.The temperature rise line will move toward the upstream of the drain close to the water intake.When the outlet position changes,the diffusion of warm water in the river is affected by the boundary conditions of the river bank.After the warm water coast spreads,the isotherm will be parallel to the river.3)In the case of changing the angle of the drain outlet,the flow of the river becoming large;the discharge angle has a small effect on the range of temperature and drainage.The situation is weak when the situation is reversed.According to the calculation,the temperature and drainage influence range can be effectively controlled when the intake port is located at the position 2 and the outflow angle is 56°.