PROCESS
Heat Exchangers in Renewable Diesel Production BY JOHN MICHELIN
Due to the small size of hydrogen molecules, metallurgical selection, design features and fabrication procedures are of utmost importance in heat exchanger manufactures. PHOTO: EXCHANGER INDUSTRIES LTD.
The production of this traditional biodiesel relies on the use of Although the COVID-19 pandemic reduced deheat exchangers in many areas, such as heating and cooling methamand for all types of fuel, as the economy recovers, nol, evaporation and condensing, as well as heating biodiesel to imdemand for gasoline and diesel is recovering rapidly. The price of biodiesel in North America rose more than 50% last year, partly driven by the discrepancy between demand and production capacity. According to Advanced Biofuels Canada, Canadian biodiesel consumption in 2020 amounted to 334 million litres (88.2 million gallons). A recent report filed with the USDA Foreign Agricultural Service’s Global Agricultural Information Network suggests that Canada could have 3.27 billion liters (863.84 million gallons) of renewable diesel production capacity in place within the next four years. A number of high-profile biodiesel and renewable diesel projects have been announced in the country to help meet this growing demand. Biodiesel is traditionally produced by the transesterification of vegetable oil or animal fats into fatty acid methyl esters (FAME) via the addition of methanol to the fatty triglycerides found in the vegetable oil at high temperatures and pressures. The resulting biodiesel is then usually blended with mineral diesel (typically at rates between 5% and 20%) for use as a road fuel. In 2021, the average rate of biodiesel blending in Canada was 2.8%.
prove flow rates, heat recovery and the thermal hydrolysis of advanced feedstocks. A Changing Role One use of heat exchangers in the biodiesel production process is the condensation of methanol (either pure methanol or a mixture of gas vapor phases) to recover and purify the methanol from the biodiesel after esterification and transesterification. This recovery is often vital to the renewable nature of the process, and to help reduce production costs. To ensure that the recovered methanol is of suitable purity, the heat exchangers used for the condensation (often under vacuum conditions) must be carefully designed to meet tight thermal tolerances. However, as the biofuel industry moves from first generation oil-based biodiesel production (using feedstocks such as canola oil) to second- and third-generation renewable diesel (based on woody biomass), the role of heat exchangers in renewable diesel production is also changing. They are becoming an intrinsic part of the new and novel production processes that are being developed.
CONTRIBUTION: The claims and statements made in this article belong exclusively to the author(s) and do not necessarily reflect the views of Biodiesel Magazine or its advertisers. All questions pertaining to this article should be directed to the author(s). 26
BIODIESEL MAGAZINE
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2022 SUMMER EDITION
