Role of Asphaltenes in Inhibiting Corrosion and Altering the Wettability of the Steel Surface
Abstract Asphaltenes (heptane insolubles) from a variety of crude oils have been identified previously as contributors to inhibition of internal corrosion of mild steel pipelines. However, the mech...
Model Compound Study of the Mitigative Effect of Crude Oil on Pipeline Corrosion
Internal corrosion of crude oil pipelines can lead to spills that can be very costly, both financially and environmentally. The corrosion is controlled mostly by mitigation methods, such as through design or by the use of corrosion inhibitors. However, it has been observed that some, but not all, crude oils can have an inhibitive effect on their own. There are different mechanisms for crude oils to mitigate corrosion, such as inhibition through the water phase by inhibitor-like molecules native to the crude oil, wettability alteration from water wet steel surface to oil wet, thereby limiting the access of the water to the surface, or by lowering the interfacial tension between oil and water and facilitating dispersion of water in oil, which reduces the likelihood of corrosion by keeping the water from being in contact with the steel surface. Model compounds representative of the naturally occurring surface-active compounds commonly found in crude oil were tested for their effect on corrosion inhibition, w...
Increasing pulp yield in kraft cooking of softwoods by high initial effective alkali concentration (HIEAC) during impregnation leading to decreasing secondary peeling of cellulose
Abstract Pulp yield can be improved by a more homogeneous delignification of the chips, achieved by improved impregnation prior to the cooking stage. Complete and efficient impregnation is obtained by increasing the diffusion rate by means of an impregnation liquor with a high initial effective alkali concentration (HIEAC). In the present study, the effect of HIEAC in the impregnation was evaluated and compared to a reference impregnation procedure and a prolonged impregnation. After the various impregnation scenarios, the alkali concentration was always adjusted to the same level in the beginning of the cooking stage. Impregnation with a HIEAC resulted in yield improvements by 1–1.5% units, due to a higher cellulose yield and possibly also to higher yield of glucomannan. The HIEAC with an even alkali distribution within the chips prior to the cooking stage resulted in a more uniform delignification carbohydrate degradation. Yield increase obtained by uniform delignification is due to both decreased shives content as well as less secondary peeling.