Modeling and Optimization of Ammonia Reactor using Shooting Methods

Ammonia production depends on temperature of feed gas at the top of the reactor (top temperature), the partial pressures of the reactants and the reactor length. The optimal design problem requires obtaining the optimal reactor length with maximum economic returns corresponding to a top temperature of 694K. This paper presents an alternative approach in solving the boundary value problem and at the same time determines the optimal solution. Shooting methods, namely single and multiple-shooting methods are used. The software used for this modeling is MATLAB version 6.1. The ordinary differential equation (ODE) integration routine technique used is ‘ode45’ and the optimization routine of ‘FMINCON’ is selected for multiple-shooting. The profiles of 2NN, Tf and Tg at a top temperature of 694K were generated. From the results obtained, this temperature yields an objective function value of $5.015 x 106 per year at an optimum reactor length of 6.695m. The objective function and reactor length values agree with the latest literature work using Differential Evolution (DE) approach, and multiple-shooting performs better than single-shooting under bad initial guesses of the reactor length.