Anti-freezing of natural draft dry cooling system of power generation by water re-distribution during winter

Abstract

The freezing risk of heat exchangers of the natural draft dry cooling system (NDDCs) in winter has great threaten on the safe and efficient operation of thermal power generating unit. This study concentrated on the potential of waterside re-distribution to relieve the adverse weather effects during winter. Based on the requirements of the thermal cycle and cooling system, a global control anti-freezing method with water flow distribution for NDDCs under crosswinds during winter was proposed. Taking the operation cost as the objective function, the Lagrange multiplier method combined with the so-called entransy dissipation analysis was employed to obtain the optimal results. A 660 MW supercritical coal-fired power generating unit was taken as an example to show the applications. The results indicated that energy saving potential of cooling water re-distributions increased with ambient natural wind, but also with the increase of total costs during hasher freezing environment. The saved consumption cost of coal would cover the growth of pump power. Compared with the previous research, the maximum savings of operation cost can reach 1.11 g/kWh after optimization.