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Fengxi Operations Department takes decisive action to address issues with the circulating water / Author/Source: Lu’an Chemical Fengxi Group / Date: 2022-03-18 / Clicks: 18 On March 16, 2022, the temperature difference in the heat exchangers of Fengxi Operations Department’s purification and synthesis workshops decreased, resulting in reduced heat exchange efficiency. To improve this efficiency, the department decided to enhance the quality of the circulating water by routinely adding sodium hypochlorite as a disinfectant to the water tank of the second circulating water cooling tower. However, due to the recent rise in temperatures, microorganisms in the circulating water have multiplied and their numbers have increased. When fungicides are added to the cooling tower water tank, they react rapidly with these microorganisms, resulting in the formation of large amounts of foam. In the air separation plant, air cooling towers must avoid having foam in their cooling water. If there is a large amount of foam in the water of the air cooling tower, it makes it difficult to separate gas from liquid, resulting in air leaving the tower containing a significant amount of water. The most obvious sign of this is an increase in the resistance of the air cooling tower. At 11:40, a bactericide was added to the cooling tower; at 12:45, the resistance of the air-cooling tower rose rapidly from 10 kPa to 25 kPa, triggering an alarm from the central DCS system – the situation was extremely critical. The leadership of the Fengxi Operations Department responded promptly by assigning cadres and managers from the air separation workshop to stay on site in order to maintain stable operating conditions ； All personnel from various departments, as well as cadres and managers from other workshops, went to the second circulating water station to remove the foam from the cooling tower basin ； At the same time, contact the chemical supply company to quickly add defoamer to the tank. The foam removal personnel remain at their posts, working diligently and responsibly; whenever foam appears in the cooling tower tank, they promptly remove it. Everyone worked overtime, taking turns going back for lunch, and returning to work promptly after eating to continue the salvage work. The air separation plant activated emergency measures: the pre-cooling system reduced the flow rates of cooling water and chilled water, and the resistance was lowered by appropriately decreasing the amount of reflux liquid in the air coolers ； The chiller increases its load, lowering the temperature of the chilled water, which in turn reduces the exit temperature of the air-cooled tower and thus decreases the moisture content of the air entering the purification system. The compression system constantly monitors the pressure at the three outlets of the air compressor, striving to minimize pressure fluctuations in order to prevent the air cooling tower from carrying water due to such fluctuations. The on-site operator for air separation shall go to the purification area to check whether water is being discharged from the valve for releasing free water at the molecular sieve inlet; if a large amount of water is discharged, they must immediately notify the control room to initiate an emergency shutdown. The air separation control operator constantly monitors the carbon dioxide level at the outlet of the purification system; an emergency shutdown is initiated immediately once this level reaches 1 ppm. During the switching and regeneration of the molecular sieve, the volume of gas used for regeneration was increased from 40,000 Nm3/h to 42,000 Nm3/h, and the cold blowing time was increased from 126 minutes to 130 minutes, thereby ensuring thorough regeneration of the molecular sieve; the peak temperature during cold blowing reached 135°C. After 4 hours of relentless effort, the resistance of the air-cooled tower was finally reduced to normal levels.