Abstract: Styrene monomer is active and liable to form polymer by polymerization reaction. The fouling of styrene polymer is an important factor affecting the long cycle operation of styrene plant. By analyzing the process of styrene production and the principle of ethylbenzene dehydrogenation reaction, and analyzing the blockage in the drain line of the air cooler in the dehydrogenation process in detail, it is found that the reason of the blocking in the drain line of the air cooler is caused by stilbene crystallization. The existence of stilbene, a by-product of ethylbenzene dehydrogenation, and its influence on the blocking of styrene unit were systematically proposed. According to the properties of stilbene and the experience in the production process, the countermeasures and solutions for the crystallization blocking of the air cooler discharge pipeline were put forward, which could provide theoretical guidance and practical reference for the long-term stable operation of styrene unit.

Key words: stilbene, ethylbenzene dehydrogenation, styrene, thermal reaction, invalid area, polymer, blocking