ENVIRO-COAT: ENVIROnmentally assisted, engineered Corrosion prOducts for Aqueous corrosion miTigation

点击翻译按钮获取中文摘要

One of the most pertinent threats to successful operations in the energy sector is internal corrosion of carbon steel pipework when transporting high temperature (>120oC) aqueous media. This degradation mechanism is apparent in the nuclear, oil and gas, carbon capture and storage and geothermal industries to name a few. Failure to manage internal pipeline degradation properly results in unexpected failures, leading not only to financial losses, but significant leaks can also have severe environmental consequences. The most common method of corrosion mitigation for carbon steel pipelines is via the addition of corrosion inhibitors to process fluids. However, such chemicals typically have a poor environmental profile and those which conform to European legislation regarding toxicity and bioaccumulation characteristics typically lack the required efficiency at elevated temperatures to suppress corrosion to acceptable levels. In the context of imidazoline chemistries (one of the most common classes of molecules used in industry) the poor inhibition is attributed to their propensity to undergo hydrolysis into their less efficient pre-cursors. In addition to these challenges, the cost of corrosion inhibitors over the lifetime of a facility can be particularly high. In 2016, the annual expenditure on corrosion inhibitors in Europe was in excess of £2 billion, with power generation and oil and gas sectors occupying the two largest proportions of this share.It is apparent that a step change is required relating to how internal pipeline corrosion is controlled in high temperature aqueous environments if carbon steel is to continue as the most favourable material of choice in high temperature environments. This proposal focuses on engineering a solution to suppress corrosion which is cost effective and greener for the environment.The proposal focuses on harnessing the protective properties of corrosion products which naturally form on the internal walls of carbon steel when exposed to high temperature aqueous media. The most commonly observed corrosion product at elevated temperature is magnetite, an iron oxide which possesses unique magnetic and electrical properties. Although magnetite has been shown to provide an effective barrier to uniform corrosion of carbon steel, its electrically conductive nature allows this oxide to support electrochemical reactions which results in localised corrosion occurring through galvanic effects. The intention of this proposal is to identify a method of augmenting the magnetite structure to suppress its electrochemical activity, producing a layer which provides superior protection against both general and localised corrosion compared to conventional corrosion inhibitors.In order to augment the magnetite layer, a method of co-precipitation in the presence of transition metal ions will be adopted. The hypothesis for this work is that the incorporation of trace amounts of transition metal ions into the crystalline lattice of magnetite (supplied directly via the solution or from within the corroding metal itself) will be sufficient to alter the layers electrochemical activity. The ability of transition metal to modify the chemical and physical properties of magnetite has been demonstrated in other disciplines (e.g. catalyst development). However, such an approach has never been instigated in the context of corrosion management.By selection of appropriate transition metals which exhibit zero or minimal toxicity at the required concentrations for augmenting magnetite, a 'batch' method of treatment, or superior alloyed carbon steels can be developed, eliminating the requirement for continuous injection of corrosion inhibitors. These approaches will provide more cost effective, efficient and greener alternatives to the deployment of conventional organic corrosion inhibitors.