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Equipment maintenance carried out by the Public Utilities Center of Enehua. Author/Source: Enehua. Date: 2022-04-09. Clicks: 12. Cleaning and maintenance of the air cooler system in the air separation unit. An air cooler is a device that uses ambient air as a cooling medium, which flows over the finned tubes to cool or condense the high-temperature process fluid inside those tubes; it is also referred to as an “air cooler” or an “air-cooled heat exchanger”. Using an air cooler instead of a water cooler for the condensation cooling of the medium not only helps save water but also reduces water pollution. In addition, it offers advantages such as low maintenance costs, safe and reliable operation, and a long service life. Due to the recent significant rise in temperatures, the frequency conversion of the fans is operating at near full capacity. In light of the current operating conditions, the center’s management developed a plan for cleaning the air coolers; cleaning of the fan fins began on March 27, 2022, on a per-unit basis, in order to remove dust from the fins, reduce air resistance, and maintain cooling efficiency. After two days of cleaning, the heat exchange efficiency of the fins was significantly improved; the steam consumption of the unit decreased, as did the electrical power used by the fans. The use of variable frequency drives was reduced, achieving the desired results and providing a solid foundation for the stable, efficient, and optimal operation of the installation. The Utility Engineering Center organized the replenishment of pearlescent sand in the cryogenic tank. The cryogenic tank is one of the key components of air separation units; it contains important equipment such as distillation towers, main condensation evaporators, plate-fin heat exchangers, and crude argon towers. Since it operates in ultra-low temperature conditions, it is particularly important to conduct inspections for its thermal insulation properties. Due to maintenance work, the cold boxes of Series 1 and 2 of the air separation unit at the Utility Center were filled with perlite in September 2018 and June 2020 respectively. As a result of prolonged operation, the perlite within these cold boxes settled naturally, creating gaps. If the perlite is not replenished in a timely manner, the low-temperature equipment and pipelines inside the boxes will frost over, leading to a loss of cooling capacity and a decline in the insulation effects. The air separation unit undergoes special maintenance of the cryogenic tank twice a month, with a focus on checking aspects such as the settlement of pearlescent sand, the shape of the cryogenic tank, and the operation of the sealing gas system. During the special maintenance inspection on March 25, it was found that there was significant settlement of pearlescent sand, which required replenishment. On March 31, the center arranged for the operation team to use their break time to refill the pearlescent sand in the cold boxes of series 1 and 2. After two and a half hours of continuous hard work, more than 200 bags of pearlescent sand were transferred and refilled. The team members overcame the challenges posed by dust and did not shy away from the hard work, successfully completing the task of refilling the pearlescent sand. This action eliminated the risk of poor insulation properties in the cold boxes, thereby ensuring the efficient operation of the air separation unit.