(190b) Modelling the Feasibility of Variable Electrified Operation: A High Purity Distillation Column Case Study

The transition to renewable electricity grids, and the electrification of industrial processes to replace fossil fuel energy are powerful recent developments that are promising to be potential solutions to achieving significant greenhouse emissions reductions even towards net zero in industrial production processes. Generally, grid electricity is perceived as a stable and reliable resource that can be accessed on demand. However, that is not always the case for large industrial users, and a key challenge that must be overcome is the inherent uncertainty of the electricity supply by renewable sources, as well as in pricing.

In methanol production, the concept of using electrolysis and CO2 capture is being explored as a way of replacing reforming to produce syngas for “green” methanol production. With the omission of the reforming process which supplied energy as steam for the process, there is now a need to electrify the effected downstream unit operations.

Distillation is a key unit operation in chemical operations that consumes a large amount of energy for reboiler duty and holds the key to making on specification AA grade methanol that is used in chemical processes. A key challenge for operating such a distillation column in an electrified operation is not only the inherent uncertainty of availability, but also the pricing of electricity.

In this work we explore the running of a validated digital model of a real distillation plant case study both dynamically to counter uncertainties such as a sudden large reboiler duty drop, as well as through the proposal and the use of the distillation column as a “process battery”. To operate the distillation column in such a manner means the traditional process control and operating regimes, that are focused on maintaining steady column operations under all conditions require a major re-think. This work explores, using the case study, the implications of running a high purity distillation column as a “process battery” as a means of countering of extremely volatile reboiler duty availability that is a possibility with electrified operations. A new control philosophy is tested, and its response to a volatile electricity market and/or supply, and conclusions and recommendations for future work are made.