Operability Analysis for Design and Control of a Modular Steam Methane Reforming Process

Modular systems are the up and coming design in the chemical industry. These systems can take advantage of new intensification strategies that can reduce the size of the chemical process. A newly developed microchannel reactor was considered for process synthesis and design of a modular steam methane reforming (SMR) model (Tonkovich et al., 2004). This microchannel reactor integrates heat transfer and an endothermic reaction to eliminate the need for multiple reactors and a high temperature furnace used in conventional SMR processes. However, only guidelines for the operation at the laboratory scale (pair of parallel microchannels) are available in the known literature. On a commercial modular scale, the design is expected to have multiple microchannels and present a drop in heat loss from around 35% to less than 5%. In this work, operability analysis is used to study the operation of the microchannel design when scaled up from laboratory to a commercial modular scale. In particular, this analysis tells how to adjust the amount of fuel that undergoes combustion and the total amount of natural gas and steam intake considering heat losses. The operability analysis also accounts for perturbations in the natural gas composition and checks the disturbance ranges that the design is capable of handling.

The microchannel reactor design is shifted to a commercial modular scale SMR model by increasing the number of microchannels to about 6,000. A simulation of the microchannel reactor in Aspen Plus is developed and the operability analysis is performed in MATLAB using the Process Operability App (Gazzaneo et al., 2020). For flexibility of the design, the system behavior related to disturbances in the methane concentration of the natural gas inlet is analyzed. The following outcomes were obtained and will be discussed in the presentation: (i) operating regions for feasible operation at the commercial scale; (ii) reduced fuel utilization of about 34% by the microchannel reactor; and (iii) flexibility analysis of the microchannel reactor to achieve the intensified operation over all expected disturbances in natural gas composition.

References

Gazzaneo, V., Carrasco, J.C., Vinson, D.R., Lima, F.V. “Process Operability Algorithms: Past, Present and Future Developments.” Ind. Eng. Chem. Res., vol. 59, no. 6, 2020, pp. 2457-2470

Tonkovich, A.Y., Perry, S., Wang, Y., Qiu, D., LaPlante, T., Rogers, W.A. “Microchannel Process Technology for Compact Methane Steam Reforming.” Chemical Engineering Science, vol. 59, 2004, pp. 4819-4824