Digitalization-enabled optimization of cooling water chemicals in an LNG plant
The implementation of digital technologies in industrial processes is reshaping efficiency and cost management . This paper explores the case of an LNG plant in Africa that utilized a digital dashboard and systematic trials to optimize the use of cooling water chemicals , leading to significant operational and financial benefits .
By Dr . Anal Chavan , Lead Utilities Technologist , Nigeria LNG
Digital dashboard for monitoring cooling water systems One of the liquefied natural gas ( LNG ) plants in Africa includes water-cooled heat exchangers ( HX ’ s ), where cooling towers play a crucial role in production performance . A collaborative effort between utilities technologists and information technologists resulted in the development of a digital dashboard . This dashboard not only showcases operational metrics like supply temperatures , basin levels , and the availability of the chemical dosing system but also highlights critical factors such as cycles of concentrations , water chemistry and microbiology ( in terms of corrosion indicators , scaling indicators , deposition indicators and bio-fouling indicators ), that directly impact the efficiency of the HX ’ s . Ultimately , this tool enabled technologists to conduct daily interventions , ensuring that cooling water chemistry and microbiology are maintained within specifications for over 90 % of the time .
Laboratory trials for chemical dosing optimization Cooling water chemistry consists of corrosion inhibitors , scaling inhibitors , oxidizing biocides and non-oxidizing biocides ( NOB ’ s ) to control corrosion , scaling and bio-fouling in cooling water circuits including HX ’ s . It was observed that consumption of NOBs at this plant was nearly four times higher compared to similar plants globally . However , sudden reduction in NOB ’ s poses a risk of bio-fouling in HX ’ s with the potential of microbial induced corrosion . Thus , number of mitigations were put in-place . Firstly , a 100-day pilot trial was initiated in a laboratory setting , simulating field conditions ( in terms of temperature , aerobic conditions , compensation for evaporation losses , slip stream filtration and blow-down ). Secondly , an additional method in terms of ATP test kit was introduced to measure the bacterial count / cleanliness of the system , which measures the ATP in 10 seconds . As this ATP test was not a standard test , a limit for this parameter was defined in-house based on Manufacturer ’ s recommendation . Thirdly , this digital dashboard was utilized for closed monitoring . In the laboratory , the trials consisted of two sets : one with normal NOB dosing ( Control ) and another with reduced NOB dosing ( Experimental ) ( Fig . 1 ). After 80 days of trial , it was found that there was no significant differences between the control and experimental sets in terms of pH and conductivity ( which impact HX integrity ), Total Suspended Solids ( TSS ) ( a deposition indicator ), and Total www . heat-exchanger-world . com Heat Exchanger World March 2025
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