[Learning from Others] Lu’an Chemical adds coagulators to its MTO units to address the problem of wax formation caused by heavy hydrocarbons

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Recently, the Olefins Plant of Lu’an Chemical Hengtong Chemical Company overcame the problem of wax formation caused by heavy hydrocarbons by installing coalescers in the MTO unit, thereby achieving improvements in safety, efficiency, and environmental protection – all of which contributed to the stable operation of the unit. 　　As a key step in olefin production, the MTO reaction results in trace amounts of heavy hydrocarbons in the product gas, which act as hidden obstacles to the efficient operation of the plant. After being cooled by the cooler, these heavy hydrocarbons condense to form oily substances that adhere to the inner walls of heat exchangers, tower bottoms, and pipes, gradually turning into wax. The cumulative wax deposition not only reduces the heat exchange efficiency of the heat exchanger, leading to energy waste, but it also disrupts the operation of the tower and bottom vessel and hinders material transfer; in severe cases, it can even block the heat exchanger, causing the compressor to overheat and shut down, thereby threatening the stable operation of the installation. 　　Faced with production challenges, the plant analyzed the causes of wax formation and developed solutions, by adding a coalescer to the oil skimming process at the floating head exhaust port of the E-1008 heat exchanger. Its core principle is to utilize the special properties of the coalescing filter element to efficiently separate the oil-water mixture present in the water system as well as that discharged from the product separation tower, thereby ensuring complete separation of the oil from the water. The separated water can be directly returned to the system for reuse, enabling efficient recycling of water resources, while the condensed heavy oils are recovered and taken away for further use, thus achieving resource recycling. This process optimization prevents the accumulation of oils and wax within the equipment from the very beginning, effectively solving the problem of wax formation that hinders production and allowing equipment such as heat exchangers and reactor bottoms to operate efficiently again.