A massive quantity of municipal solid waste (MSW) is generated yearly worldwide. The treatment and final disposal of this waste are both financially and environmentally expensive. Also environmentally aggressive, the NH3 production process releases great amounts of CO2 in the atmosphere. However, this process is essential for the global economy. In this work, the economic performance of a plant, which combines MSW gasification with the ammonia production process, was studied. The results showed that the project has a low rate of return (0–4%). However, municipalities, which spend billions yearly on MSW treatment, could already benefit from it. The gasifier is the most expensive equipment in the process (approximately 55% of the total installed cost). Refrigeration and electricity are both a burden for the operating cost, accounting for almost 70% of it. Further reduction in the gasifier price and an improved energetic integration could boost the economic performance.

A 2D steady-state phenomenological model used for sizing a multitubular catalytic reactor for water-gas shift reaction is presented. The model contemplates momentum, mass, and energy balances. In addition, the thermodynamic behavior is described by the Peng–Robinson–Stryjek–Vera equation of state. After the model validation, a set of equations was used in an optimization procedure to find the optimal reactor’s dimensions and operational conditions, minimizing both capital and operating expenses. The results were compared with data from the literature, and the water-gas shift reaction has proven disadvantageous at a low temperature, with heat exchange, because this considerably increases the required catalyst amount. The multitubular reactor has shown to be appropriate in the studied temperature range (430–520 K) only for a more active catalyst or for a more exothermic reaction.

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