Corrosion in biomass/fossil fuel co-processing: fundamentals and mitigation practice

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At present, more than 80% of all energy and 90% of all organic chemicals are derived from finite fossil fuel resources. The emerging co-processing of biomass with fossil fuels has been growing to make use of renewable biomass as a fuel source. Since co-processing is still in the research stage, leveraging existing refinery infrastructure is an attractive initial option. The benefits of co-processing for a refinery include reducing the associated greenhouse gases (GHG) emissions, enabling the gradual independence from fossil sources, and rendering low-carbon-highly-sustainable fuels. All these benefits are directly related to the economic values to Canada. In response to the carbon taxes, GHG emissions are increasingly monitored and priced. The competitiveness of the refinery sector can be affected by its level of GHG emissions. On the other hand, crude oil purchasing today represents over 90% of the cost structure of a refinery and is therefore a major area for achieving profitability and reducing costs. In the meantime, the biomass co-processing technologies are facing severe challenges. Of particular note is that biomass sources have high acidity and high concentrations of organic oxygenates, which can result in increased corrosion issues. While adding a small percentage of renewable feedstock to the operations of refinery units sounds simple, there must be a limit to the ratio of biofuels mixed with fossil fuels. One should consider possible corrosion risks directly affected by this limit to metallic structures from the existing refineries which have been built and used for decades. That is, what are the optimum mixture ratios of certain biomass sources for acceptable corrosion rates? Beyond what is acceptable, what could we do to protect these existing structures? Exploring innovative coatings could be an effective solution as protection of metals against corrosion and oxidation by surface modification is a key technology for many industrial fields such as waste treatment. Detailed studies of corrosion, using modern surface analysis and electrochemical techniques, have explored the degree of corrosion risk to a variety of engineering alloys in waste-to-energy industries. This proposal will discuss a program to discover the corrosion mechanisms in the emerging fossil fuels/biomass co-processing technologies, and to identify new coatings and/or surface modification methods that will reduce corrosion and preserve safety and profitability. A long-term goal is to design a pilot/prototype facility to process a mixture of biomass and fossil fuel, so that questions, such as, what construction materials are economically suitable and reliable for new co-processing refinery units? By answering this question, this program will explain how corrosion and surface modification studies could revolutionize the biomass co-processing industry.