Water Vapor Recovery Technology Of Circulating Cooling Tower In Chemical Plant

In recent years,China’s water resources situation has become more and more serious,and the scarcity of water resources in some areas has restricted economic development.The water consumption of circulating cooling towers in chemical plants accounts for more than 45% of the water consumption of chemical plants,and this work explores the use of suitable cooling working fluids to condense the moisture taken away by saturated wet air at the top of the circulating cooling tower to recover the circulating water lost due to evaporation,and study the technical feasibility,economic feasibility and HSE(health,safety,environmental protection)feasibility.In this work,experimental equipment such as circulating cooling towers and condensate pipes was calculated and designed,a suitable cooling tower water and gas circulation process was designed,and experimental devices were built according to the process flow chart and pipeline instrument flow chart.On this basis,different cooling working fluids were selected to condense the wet air at the top of the cooling tower,and the influence of different factors on the temperature and water saving of saturated humid air at the top of the tower was tested,and the optimal conditions conducive to water recovery were explored.Finally,the economic analysis of the amount of condensantion is carried out,the safe,environmentally friendly and economical cooling working fluid is determined,and the industrially feasible process flow is designed.Under the circulating water volume of 10L/h,R245 fa was used as the cooling working fluid,and the data of air flow,air outlet temperature,coolant inlet,coolant outlet and temperature after throttling and water saving under various working conditions were tested,and the impact of the change of air inlet flow on water saving was analyzed.The experiment shows that the circulating water temperature has a greater impact on water saving,and the larger the circulating water temperature,the better the water saving effect.An increase in air inlet temperature will also improve the water-saving effect,but the amplitude is not obvious;Increasing air flow will also significantly improve water savings.Ambient air and moisture-carrying wet air were selected as cooling fluids for comparison,the process flow was redesigned,and pipelines were configured for experiments.The experimental results show that with the increase of cooling air flow,the outlet temperature of humid hot air at the top of the tower decreases and the water saving increases.However,the decrease of cooling air temperature does not change significantly in the increase of water saving;Before the water content in the cooling air reaches a certain value,as the water content of the cooling air increases,the cooling water volume of saturated wet air at the top of the tower will also increase.20m~3/h ambient air can recover more than 45% of the water at the top of the tower,and 10m~3/h ambient air can recover about 19% of the water vapor at the top of the tower.Finally,experiments were carried out to determine the amount of cooling working fluid and economic evaluation was carried out.The use of cooling working fluid R11 for comparison,it was determined that the use of R245 fa as cooling working fluid is more economical and environmentally friendly.Considering the power consumption cost and water saving of the cooling working fluid metering pump,the appropriate cooling working fluid consumption was determined,and the top temperature of the tower can be cooled to 30°C under the processing capacity of 1t/h circulating water and air flow of 337.6 m~3/h,and the cooling working quality consumption of the top of the tower when it reaches breakeven is 1013.7L/h,and the recoverable water volume is17.93kg/h.In the case of cost recovery,an industrially feasible process plan is proposed.When saturated with moist air at the top of the R245 fa cooling working fluid condensing tower,more than 70% of the evaporated water loss can be recovered without additional energy consumption,with considerable economic and environmental benefits.This work adopts 10～30 °C room temperature cooling working fluid.Phase change occurs in the heat exchange process,and then throttle valve or turbine expansion can be used to recover energy,while the saturated vapor pressure is low,heat loss is less,and the safety is high,which has guiding significance for the development of water saving work in cooling tower.