Non-Phosphorus Water Treatment Program Enhances Heat Exchanger Performance

摘要

Scale formation and deposition are fundamental problems in cooling water systems.Scale interferes with heat transfer by forming an insulating barrier on heat exchange surfaces.Scale also promotes localized corrosion and restricts water flow.Consequently,scale formation and deposition may result to huge economic losses due to their impact on heat exchanger operations,mitigation measures and unscheduled equipment shutdown.One of the most prevalent scale in industrial water systems is calcium phosphate that is formed from calcium hardness and from orthophos-ter systems is calcium pnosphate that is formed from calcium hardness and from orthophos-phate.Recently,the problem of calcium phosphate scaling in industrial water system has become increasingly important.Higher orthophosphate levels are being encountered in cooling water systems due to increased water reuse,use of low quality make-up water such as wastewater treatment plant effluents and the use of organic phosphonate scale and corrosion inhibitors that are degraded to orthophosphate.The increased orthophosphate levels,combined with alkaline operating conditions and higher surface temperature can lead to the formation of highly insoluble calcium phosphate scale deposits.This paper discusses the use of a non-phosphorous corrosion inhibitor program in alkaline conditions.Eliminating one of the sources of phosphate allows for better performance of heat exchanger tubes as evidenced by lower approach temperatures.In addition,utilizing a non-phosphorous corrosion treatment program extended the exchangers'cycle on turnaround even for heat exchangers that are ran with lower water velocity.