A win-win strategy for simultaneous air-quality benign and profitable emission reduction during chemical plant shutdown operations

摘要

Although the flaring system is designed for the safety operation in chemical plants, the intensive flaring will cause not only tremendous raw material loss, but also large amounts of VOCs and NOx, which could escalate regional ozone formation and elevation under the solar radiation. Thus, it will be a win-win situation to preform air-quality conscious flare minimization (FM) for chemical plants, so that both environmental and industrial sustainability could be promoted. In this study, a systematic multi-scale methodology has been established to identify and demonstrate the win-win strategy for simultaneous airquality benign and profitable emission reduction during chemical plant shutdown (CPS) operations. The major contribution of this study is that process-level dynamic simulations via Aspen Plus Dynamics have been seamlessly integrated with the regional-level air-quality modeling via CAMx to simultaneously accomplish both flare source savings and ozone impact minimization during the CPS operation. Case studies have indicated that the base case of CPS without FM could have a serious effect on the air-quality (1.6 ppb 8-h ozone observed). However, the improved case of CPS based on FM would significantly reduce such an ozone impact (only 0.1 ppb 8-h ozone observed); meanwhile the flare source and CO2 emission reductions, as well as the plant economic savings are respectively 165.2 tons, 479.1 tons, and US$ 133,945.6. (C) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.