Fused chemical reactions: The use of dispersion to delay reaction time in tubular reactors

Fused chemical reactions are delayed exothermic reactions. An axial dispersion model is used to simulate the flow of alternately injected pulses of reactants separated by an inert. There is a delay in reaction and heat release because the reactants have to disperse through the inert spacer to react. The feasibility of this technique is described for the reaction between ammonium chloride and sodium nitrite catalyzed by acetic acid. This technique can be successfully applied to the effective dissolution of wax deposited in subsea pipelines. The delay in the reaction is required to supply heat to regions further down the pipeline that are more susceptible to wax deposition. Simulation results show that the delay in the heat release depends on the width of the inert spacer as well as the catalyst concentration. However, the amount of heat released depends on the inlet concentrations of the reactants. Simulations can successfully determine the inlet concentrations of the reactants and catalyst as well as the inert spacer width for a desired temperature profile inside the pipeline.