What are the inhibitors (polymerization inhibitors) and oxygen scavengers used in ethylene plants?
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What are the functions and principles of the inhibitors and oxygen scavengers used in ethylene plants, and what are the differences between them?
We add antipolymerizers to the feed and the bottom of the depropanization tower. The material contains unsaturated and diene hydrocarbons, which tend to polymerize and coking at the operating temperature and pressure, thereby blocking the trays and heating coils and affecting separation and heating efficiency; hence, antipolymerizers need to be added. Principle: The polymerization inhibitor molecules react with chain radicals to form non-radical species or low-reactivity radicals that cannot initiate further reactions, thereby terminating polymerization. Isn’t the substance that can completely terminate the free-radical polymerization of olefin monomers, an oxygen scavenger, essentially a deoxygenizer? The difference is obvious.
For the pre-depropanization process, a terpene inhibitor is generally added to the depropanization tower; the specific composition of this inhibitor is unknown, as manufacturers usually keep it confidential. The debutane column is fed with an antioxidant; it is likely that butyl radicals are relatively sensitive to oxygen, and in the presence of oxygen, they tend to generate free radicals. Therefore, in addition to inhibiting polymerization, the debutyrination tower also needs to have antioxidant properties; it should be a composite additive
Which location do you mean by for injecting the polymerization inhibitor? In an ethylene plant, the locations where polymerization inhibitors are injected include the quench oil tower, the gasoline reflux line, the depropanization tower, the cracking gas compressor, and the debutane tower. Generally, some of these inhibitors are used to prevent the formation of larger molecules from smaller ones, while others are used to prevent free-radical polymerization
Thank you for your explanation, it’s good