Abstract:

Based on the freeze blockage situation in the low-pressure methane side of cold box in an ethylene plant as well as the reaction mechanism of freeze blockage in cold box caused by NOx, the test data of NOx, nitrogen compounds and total-N at different sampling positions in each recuperative stage of cracking process are introduced. The root cause of NOx formation in cold box is that the NO introduced from cracking unit reacts with the O2 in cold box, and NOx is formed from the nitrogen compounds in raw material.

Key words: cold box system')">

cold box system, low-pressure methane, NOx, freeze blockage