(130d) Dynamic Simulation and Optimization of Turnaround Operations Among Multiple Olefin Plants for Flare Minimization

Flare minimization (FM) in large-scale industry is a win-win practice, which benefits not only environmental sustainability but also industrial profitability. By far, available studies have almost exclusively focused on FM problems for a single plant. However, there are few systematic FM studies focusing on FM solutions among multiple chemical plants. Material exchanges (ME) among chemical plants provide an augmented freedom for material savings, energy saving and flare source reductions. For example, plant A can borrow materials from plant B with normal operating conditions to support the start-up of plant A; meanwhile, pant B can adopt off-spec products from plant A undergoing the start-up operations to recover resources for producing more potential products. Such ME operations could be designed, scheduled, and optimized through large-scale dynamic simulation studies.

In this study, dynamic simulation and optimization have been performed for FM via ME between two olefin plants.

For the ordinary start-up of an olefin plant, no any external flows will be imported, a large amount of flaring will be generated during cracked gas compressor (CGC) start-up, because the charge gas from fired-up furnaces to run CGC needs some time to reach the required flow rate. Another flare source is from the reactor, where the outlet of the reactor should be on spec before sent to the downstream. In this work, ME among three plants are studied. Plant A is at normal-working status, plants B and C are both preparing to start-up. Plants B and C could import certain flows from plant A to reduce the number of furnaces fired-up before their CGC start-ups. Meanwhile, plants B and C also export off-spec products to Plant A to avoid flaring. The amount of these material to exchanges could vary, and the start-up schedules of two plants could be different. Therefore, a series of dynamic simulations have been done to find the optimal design of start-up schedule and ME amounts, which not only generate least flaring, but also ensure plant A’s normal production and smooth starting-up of plants B and C. The obtained strategies and simulation results will provide an in-depth understanding on synergies of three plants ME operations for flare minimizations.