The present work investigates the production of sodium bicarbonate in combination with the co-utilization of saline brine and carbon capture, utilization, and sequestration (CCUS). The use of ammonia in the traditional Solvay process could be eliminated by using a modified Solvay process. This study compared the modification with the addition of three buffering additives: Ca(OH)2, KOH, and NH4HCO3. The effectiveness of these processes, using two qualities of saline brine (desalination and aquifer), is compared based on the purity of the produced NaHCO3. It was found that the use of Ca(OH)2 did not produce high-purity NaHCO3, while NH4HCO3 and KOH performed better. Desalination brine utilization with NH4HCO3 resulted in the production of high-purity NaHCO3, while the second most suitable method involved the use of KOH, and the main co-product formed was Na2CO3. Geochemical modeling is performed in order to have insights into the carbonation (in the reactor) and precipitation (in the oven) behavior of the reactions. It predicted the precipitation of mineral phases well, though kinetics might hinder some saturated solids to dissolve first. The present study shows that accurate characterization is critical to accurately assess the success of modified Solvay processes. The use of QXRD and SEM analyses, complemented with geochemical modeling, helped to better understand the processes and the formation of NaHCO3. Further investigations on diverse brines could provide for their better utilization by the geological carbon sequestration and water desalination industries that produce them.

The lamination process adds the anisotropy characteristic in the final product. This anisotropy influences the yield strength according to the direction in question, the difference between the value of the yield tension in one direction and the value of the yield tension in another direction referred to as the back stress. Naval plates were welded by the GMAW process in the longitudinal direction to the lamination and in the transverse direction, and with different thermal loads. The residual stresses were calculated by displacement coordinate points method (DCP) and the back stress was found by tensile tests in specimen subjected made with either the longitudinal lamination direction and transverse lamination direction. The material used was ASTM A131 naval steel grade AH-36. The welded plates with greater thermal load in the longitudinal direction presented smaller residual stress in this direction, in relation to the transverse lamination direction. In the welded plates with greater thermal load, in the transverse lamination direction, the displacements in different directions were close, showing that the back stress does not act reversing the displacement (flow). Finally, for the welded plates with lower thermal load, both welded in the longitudinal and transverse direction, the displacements were small. In addition, the back stress did not act reversing such displacements.

Choosing welding parameters is an important step in welding process, directly influencing in the heat input provided to welded joints. This heat input value, along with temperature distribution in welded joints, provides, to the drafter, conditions of predicting the Heat Affected Zone (HAZ) extension, the kind of microstructure to be formed, and therefore, the effects of residual stress. Three welding parameters were switched, providing different welding conditions. Each condition was analyzed by SmartWeld 2011 software and macrography to find and compare the extension of HAZ. As for the residual stresses, calculated through Displacement of Coordinated Points (DCP) method. It is possible to choose the best parameters for the welded joint by GMAW process considering the parameters in study.

Resumo Esse trabalho busca estudar os efeitos da mudança da velocidade de soldagem e o efeito da aniso-tropia no cálculo de tensões residuais calculadas pelo método de deslocamento de pontos coordenados (DPC

No abstract