Design Optimization Of Dry Cooling Tower And Feasibility Study On Reconstruction Of Wet Cooling System Into Dry

The technology dry cooling is attractive in recent decades with its superiority of zero water loss,which has been widely used in many power and chemical plants especially in coal-rich and arid region.Through mathematical modeling and concrete examples analyses,the design optimization of indirect dry cooling and the reconstruction of wet cooling system into dry have been discussed and analyzed.Firstly,the optimal design and operation analysis of indirect dry cooling with different ventilation modes are carried out.Furthermore,the feasibility of reconstructing wet cooling system into dry is studied,indirect and direct dry cooling system are discussed respectively.An optimization model for the natural draft dry cooling tower under constant heat load is put forward,with fully consideration of tower shape,crosswind velocity and the radiator layout.The critical impact factors of tower shape on the optimal design are clarified and their influences have been discussed.After optimization,and the height of tower and oufflow water temperature are reduced by about 5.01m and 0.128?respectively.The cost of cooling system is reduced by about $230,000.Besides,a design for mechanical draft indirect dry cooling system is put forward and the problem of anti-freezing in winter is discussed.Two operation schemes are put forward and compared for economic operation when the ambient temperature is lower than 0?.Compared with the scheme of running all the draught fans in frequency modulation mode,the scheme of shutting down part of the draught fans under the conditions of 465.3MW and 240.3MW thermal loads can save about 1549kWh and 3947.7kwh in an hour.The lower the ambient temperature is,the more obvious the power saving effect is.When all the draught fans are shut down,the ambient temperature is about-18.438? and-2.91? respectively,which provides theoretical basis for actual operation and regulation.Aiming at the reconstruction from wet cooling system into natural draft dry cooling system,a coupling operation mode of two reconstructed indirect natural draft dry cooling towers,a usual indirect natural draft dry cooling tower and two 660MW power units is put forward,and the feasibility and shortage of the reconstruction are discussed and analyzed.By changing the circulation water distribution,the optimal design and operation prediction is obtained,the calculation of annual water saving and optimal annual are obtained.After reconstruction,the annual water saving is about 14.49 million tons,equivalent about 8.86 million dollars.The annual cost function is established and the minimum annual cost is about 181.47 million dollarsFor a reconstruction of wet cooling system into a composite cooling system of direct dry cooling and evaporative cooling is put forward.With its requirement of cooling performance and system safety,the detailed operation in different ambient temperatures have discussed.When the ambient temperature is below 240C,direct dry cooling in frequency modulation mode can satisfy the requirement.When the ambient temperature is 24?-35?,direct dry cooling and evaporative cooling are parallel operation.The evaporative cooling is operated under its rated parameters,while the flowrate of air is regulated in dry cooling.When the ambient temperature is higher than 35?,the maximum ambient temperature in safe operation of the compound cooling system is calculated to be 37?,which provides references for operation.To sum up,the design optimization and operation analysis of indirect dry cooling tower and the feasibility of reconstructing wet cooling system into dry have been studied and discussed.The designs and calculations for various dry cooling towers and dry cooling systems have been comprehensively involved,and the better cooling performances or more economical operations have been achieved through analyses of calculation examples.This research enriches the design optimization of indirect dry cooling tower and the reconstruction of wet cooling system into dry.It provides theoretical support for the reconstruction design and optimization.It plays an important role in alleviating water shortage,reducing environmental pressure and realizing sustainable development of electric power.