Thermal resistances in stirred-tank and tubular reactors for clathrate-hydrate formation: Estimating their reactor-scale dependences

Efficient formation of clathrate hydrates is the primary condition for establishing the hydrate-based technology for various industrial applications such as the natural gas storage/transport, the capture of CO2 from industrial flue gases, etc. Because hydrate formation is an exothermic process, the heat discharge from the inside of hydrate-forming reactors can be one of the major rate-controlling processes. The thick stainless-steel walls encasing such reactors configured for high-pressure operations may provide significant resistances to the heat transfer across them. Based on the conventional schemes for calculating the hoop stress in pressure-vessel walls and the convective/conductive heat transfer in cylindrical systems, this paper demonstrates how the thermal resistances to the heat discharge from the inside of each stirred-tank or tubular reactor vary depending on the geometric scale (i.e., the diameter) and the design pressure of the reactor. In general, the thermal resistance to the conductive heat transfer in the reactor wall becomes increasingly significant, relative to the resistance to the convective heat transfer inside the reactor, not only with an increase in the design pressure, but also with an increase in the reactor diameter.