PAIRING TWO PROPRIETARY TECHNOLOGIES KEY TO POWER PLANT EFFICIENCY INCREASES

摘要

Since plant start-up, this zero liquid discharge (ZLD) power plant was challenged with maintaining condenser cleanliness and maximum power production as an apparent result of high iron and manganese in the cooling tower make-up water. As a result of ZLD operations, the cooling tower operated at 40 cycles of concentration, exceeding saturation indices. The plant had been shutting down two to three times per year to clean the condenser. Past treatment focused on inorganic oversaturation of silica, iron, and calcium. To understand the fouling mechanism, Ashland employed a proprietary monitoring and control system that accurately simulates the steady state conditions in plant heat exchangers while revealing differentiation among various causes of fouling. The analyzer uses a slip stream of cooling water routed through a heat exchanger simulation tube that passes over corrosion, conductivity, pH, and ORP probes. This diagnostic tool acted as a window into the cooling system and was essential in validating the response to the treatment program changes before they could impact plant efficiency. As a result, it was discovered that fouling rates at this facility were dependent on Oxidation Reduction Potential (ORP) and not mineral saturation. Although traditional bio-assay slides suggested good bacterial control, the analyzer results indicated that the fouling mechanism was biological in nature. Based on this information, a new proprietary biocide was recommended to treat the cooling system. The new biocide not only stabilized, but also effectively reversed the established condenser fouling. This paper reviews the actual system data that led to the proper diagnosis and program implementation. Currently, this plant is setting power generating records.