London Branch

The branch held its 34th annual Christmas luncheon at the beginning of December at the Royal Overseas League in St. James’s. 150 guests enjoyed a four-course Christmas-themed lunch before being entertained by an after-dinner speaker. The event was hosted by George Winning, the new branch chair, who took over from Polina Zabelina in November.

Before Sitting Down to Eat, there Were Pre-Lunch Refreshments, and Time for the Guests to Meet Each Other.

The After Dinner Speaker, Ian Irving.

The After Dinner speaker was Ian Irving, a popular entertainer, who gave an amusing sport-themed talk which was appreciated by the guests.

On the 18th January, (moved from the scheduled date due to transport strikes in London), Michael Harrison, Global Product Director-Linings, Sherwin-Williams, gave a presentation on “The Examination of Lining Performance in Renewable and Biofuels and Feedstocks”, sub-titled “why storing feedstocks for biofuel production presents distinct challenges for the specification of tank linings”, at the usual venue, the Lancaster Hall hotel, Craven Terrace, Bayswater.

Michael has 35 years of experience in the protective coatings industry, responsible for the development and testing of heavy-duty solvent-free linings, with subsequent roles in business support and business development. He has also been the project lead in the revision of ISO 16961 (Petroleum, petrochemical, and natural gas industries—internal coating and lining of steel storage tanks).

According to the International Energy Agency (IEA), biofuel use is growing at around 6% a year, and annual production to meet net zero emissions would need to reach over 10 EJ by 2030, requiring an average growth of around 11% per year. Biofuels have an important role to play in decarbonising transport by providing a low-carbon solution for existing technologies, such as light-duty vehicles in the near term and heavy-duty trucks, ships, and aircraft over the longer term. Indeed, according to the IEA, biofuel demand in 2022 reached a record high of 4.3

EJ (170,000 million litres), surpassing levels last seen in 2019 before the COVID-19 pandemic.

However, storing the lipid feedstocks necessary for the production of biodiesel, renewable diesels, and sustainable aviation fuels presents significant challenges for refiners. To avoid the degradation of tank linings and the subsequent corrosion of storage tanks and contamination of feedstocks, it is essential that proper consideration is given to the particular requirements of storing these materials, including the type of feedstock being stored, operating temperature, and storage duration. Failing to do so risks material contamination, tank corrosion, and even production delays. Increasing biofuel production presents one significant challenge for refiners; however, the lipid feedstocks required for biofuel refining have very different chemistries from fossil-based feedstocks, and it cannot be assumed that storage conditions—and the lining systems of storage tanks, in particular—are the same. To understand the issues faced by biofuel producers, a series of tests were conducted that revealed significant degradation of tank linings over time and at certain temperatures, raising important questions for refiners about how they store the feedstocks necessary for biofuel production and the temperatures to which they are exposed.

A two-stage test was carried out under NACE TM-0174 Procedure B, with test temperatures of 71°C, 82°C, and 93°C (based on project specifications), with evaluation at three monthly intervals extending to a minimum of 24 months. The tank lining systems evaluated included proven systems used in typical fossil fuel-derived feedstock storage applications: solvent-free epoxy phenolic, solvent-free epoxy novolac, and novolac vinyl ester glass flake. Feedstock media tested included a combination of waste cooking oil, waste cooking oil +1% water, beef tallow, and beef tallow + 1% water, as it has been reported that the presence of water accelerates the formation of free fatty acids, especially at higher temperatures.

Under phase one of the tests, the impact of higher temperatures on the test samples was apparent at relatively short exposure times. The effects of higher temperatures on solvent-free epoxy phenolic (which is rated at 135°C in crude oil) were apparent at 71°C. The effects of higher temperatures on solvent-free epoxy novolac (rated to 149°C in crude oil) were apparent at ~82°C. Both lining systems failed at 93°C. Broadly speaking, subjecting lipid feedstocks to temperatures above 60°C results in the production of Free Fatty Acids (FFAs) in lipid feedstocks, and the tests again revealed lower limits for these same two linings, with resistance up to 71°C and degradation above this temperature.

A second stage of testing involved two further elements the examination of the oil composition and how it changes at different temperatures, and the expansion of feedstocks to simulate the conditions in the earlier (water cooking oil) tests. Analysis of the oil composition revealed that, up to 60°C, vegetable oils remain reasonably stable with minimal degradation to FFAs after six months of exposure. FFAs are thought to be the aggressive component behind degradation, and this degradation accelerated at 71°C, where the oil degraded to ~12% FFA content after six months of exposure. At 82°C, the formation of FFAs is considerable (>30%). The degradation also appears to be time-dependent, with the FFA level increasing after only three months at temperatures higher than 71°C. This shows why there is no immediate breakdown and stresses the need for longer-term testing. (The normal recommended duration as per NACE TM-0174 procedure B
is 6 months).

Expanding the feedstocks to simulate the conditions in the earlier (water cooking oil) tests involved the addition of oleic acid alongside an unmodified control. This revealed a correlation with the results seen for waste cooking oil and beef tallow under phase one when laced with an additional 5% FFA, although samples with higher levels of FFAs showed rapid degradation. Analysis of these modified oils by both time and temperature of exposure clearly showed that the presence of additional FFAs accelerated the degradation of the oil. Indeed, FFA formation grew faster under these conditions.

Michael Answering Questions at the End of His Presentation.

Testing on these oils demonstrates that, as anticipated, a novolac vinyl ester system can handle the higher temperatures primarily due to the superior resistance to organic acids (such as the free fatty acids seen in renewable fuels.) However, they present greater complications (flash point, storage stability etc.) during application. The lessons learned from this performance evaluation have provided an array of selection tools for biofuel asset owners and facility managers to select the appropriate lining system for their specific processes and needs.

Michael was thanked for his interesting talk and presented with an ICorr pen in appreciation. Information about future branch presentations can be found on the back cover of this magazine, and on the events page of the Institute website. Currently all talks are being held in person at the Lancaster Hall hotel.

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