Corrosion in Biomass/Fossil Fuel Co-Processing

Sustainable and renewable energy resources are getting more attention due to the gradual depletion of fossil resources and the deterioration of the environment. Biomass is a renewable energy source with great potential. Currently, pyrolysis and hydrothermal liquefaction are two important thermo-chemical conversion processes that convert the organic constituents in biomass into a liquid fuel commonly referred to as “bio-oil”. Pyrolysis is the most widely used process for bio-oil production which operates at moderate to high temperature and atmospheric pressure without solvent involvement, while liquefaction is a low-temperature and high-pressure process with solvent participation. Liquid bio-oil produced from biomass by thermal-chemical processes has been widely accepted as one of the promising substitutes for fossil fuels. Bio-oil is energy-intensive and carbon-neutral, and attracting much attention and investment. For example, it can be co-processed with petroleum fractions in existing refineries for the production of renewable and cleaner fuels compared with refining 100% fossil fuels; it also has great potential to be blended with current marine fuels (also known as fuel oil, or furnace oil) used in a furnace or boiler for the generation of heat or used in an engine for the generation of power, to green up that industry. In order, it is necessary to have an adequate understanding of their overall fuel properties. Thorough understanding of bio-oil and its blends with petroleum fractions is a necessary precondition for researchers to develop and promote new technologies for the successful utilization of bio-oils.

Despite of the advantages as described above, bio-oils are totally different from petroleum fuels. Bio-oil produced from these processes is a complex mixture of several hundreds of organic compounds like acids, alcohols, aldehydes, esters, ketones, phenols, and oligomers, etc.. It often has the undesirable properties such as high viscosity, poor volatility, high ash content, low heating value, and high corrosivity, etc.. Therefore, when discussed with Canadian refiners or power industries, the potential of co-processing bio-oils with conventional petroleum feedstocks was generally viewed with skepticism. Even though there are several advantages of blending with bio-oil fractions, industry people will rarely risk running entirely new, entirely chemically different feedstocks without performing additional process performance tests. There are certain unknown risks. With regards to these new crude oils, stability problems during storage as well as corrosion are unknown, and might occur as a consequence due to the abundant free fatty acids in vegetable and residual oils and animal fats. Further, different bio-based feedstocks present different risk profiles to refineries and will require differing degrees of testing and evaluation before they can be integrated into the refining system. From the refiner’s perspective, they will require due diligence and a large database of results to ensure that the operations can continue to be safe, reliable, predictable and profitable before processing any biomass-based feedstocks. The requirements for co-processing crude pyrolysis oils are high. A general rule is that the closer a bio-based feedstock is to conventional petroleum feedstocks and products, the easier the path will be to integrating the bio-feedstock into refineries. The real question behind is, what are the biomass/fossil fuel mixtures that a refinery will accept? To answer this question, I propose a project on developing applicable technology pathways for co-refining pyrolysis oil and fossil fuel in a safe and cost-effective manner.

This proposal will focus on 3 fronts: (1) characteristics of crude pyrolysis oils and their blends with fossil fuels; (2) enhancing the stability and miscibility of pyrolysis oils with fossil fuels for co-refining; (3) assessment of toxicity and corrosivity of pyrolysis oils and the blends. The proposed research program will combine classical experimental methods and new surface modification & characterization techniques, leading to advances in our understanding of the co-processing technology.

Advancing the application of bio-oils by co-processing with petroleum intermediates: A review

Haoxiang Wang, Jing Liu

Scholarly Refereed Journal

The Thermal Stability and Corrosivity of Bio-oil with Methanol Addition

Haoxiang Wang, Jing Liu

Conference Proceedings