A Brazilian biodiesel plant uses the transesterification of soybean oils with the methanol and sodium methoxide catalyst excess to convert these oils into alkyl esters and glycerin. Hydrochloric acid solution is injected in the piping to neutralize free NaOH and reduce saponification of oils. After the hydrochloric acid solution, several failures of pipelines of AISI 316L and 904L steels were registered. The objective of this work is to study the austenitic stainless steel corrosion observed in the downstream piping the hydrochloric acid injection, applying computational fluid dynamics and to evaluate pH and chloride profiles using different geometries for the acid solution injection in order to avoid or mitigate the corrosive attack. The obtained results showed a good agreement with in situ observations of the pipe degradation. All the studied geometries presented evidence of a weak mixture between the polar and non‐polar species, even under turbulent flow. The elbow geometry is more effective to reduce the local corrosive attack compared to two other simulated geometries.

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-This work evaluates the impact of different radiation models on the results of Computational Fluid Dynamics (CFD) simulation of a sugarcane bagasse grate boiler. CFD has been applied extensively in the development of comprehensive models for biomass heterogeneous combustion. The model presented in this paper considers the turbulent flow represented by the standard k-ε model and the homogeneous combustion of the volatiles CH4 and CO by the Eddy Dissipation Model (EDM). Thermal profiles have been evaluated by comparing the results obtained without radiation with the results obtained with radiation represented by the P1 Approximation Method and by the Discrete Transfer Method (DTM). The discussion of the flue gas temperature and chemical composition profiles provides useful information regarding the characteristics of the internal flow and of the equipment operating conditions.