Fused chemical reactions. 2. Encapsulation: Application to remediation of paraffin plugged pipelines

Fused chemical reactions are reactions that undergo a delay before signific ant amounts of product are produced. One class of fused chemical reactions is the class of reactions triggered by an abrupt release of a catalyst. Fus ed chemical reactions have the potential of solving the problem of organic deposition in sub-sea pipelines which is a problem with enormous economic c onsequence (Singh, P.; Fogler, H. S. Ind. Eng. Chem. Res. 1998, 37 (6), 220 3). The reaction between ammonium chloride and sodium nitrite catalyzed by citric acid was chosen as an example of a fused chemical reaction system wh ere the acid was encapsulated in polymer-coated gelatin capsules. The timed release of the acid catalyst was achieved by putting an additional polymer ic coating on the gelatin capsules. The reaction kinetics and the polymer d issolution kinetics were investigated in an adiabatic batch reactor. An exc ellent agreement between simulation and experimental results in the batch r eactor was achieved. Experimental results in a flow-loop reactor demonstrat ed that the fused chemical reaction could provide a substantial amount of h eat in situ. This amount of heat is sufficient to overcome the high heat lo ss to the surroundings and to raise the temperature of the fluid above the effective temperature to soften and melt the wax deposit. The delay in heat release was found to depend on the thickness of the polymeric coating, whi le the amount and rate of heat release depended on the in situ reactant and acid concentrations.