In the past, the U.S. has imported most of the renewable diesel it uses from refiners in Asia.
The majority of these imports are consumed in California. According to the California Air Resources Board, the Low Carbon Fuel Standard was introduced to decrease the carbon intensity of the transportation fuel pool and provide an increasing range of low-carbon and renewable alternatives, which reduce petroleum dependency and provide improved air quality benefits. More recently, local and federal governments in Canada and the U.S. have created a mix of standards and tax credits to stimulate greater production of clean fuel alternatives.
Refiners can produce renewable diesel from a wide variety of readily available agricultural feedstocks, including animal fats and plant oils, as well as used cooking oils (as used by the larger foreign refiners). Government regulations and incentive programs have created a surge in interest, compelling refiners to evaluate their alternatives for renewable diesel production.
Because of the recent increases in steel prices and manufacturing delays, converting existing refining assets is extremely cost-effective versus grassroots construction projects. Conversion projects typically include upgrading the metallurgy of existing corrosion- resistant linings in pressure vessels. Therefore, conversion projects allow refiners to capitalize on shorter windows of availability, such as turnarounds, to gain critical speed to market for capture of limited tax benefits and incentives.
High-temperature, high-pressure hydrogen service
Most refiners currently use variations of hydrotreating in their process to remove impurities by mixing hydrogen with oil in a catalyst at high temperatures and pressures. These reactions are essential for the conversion process and present evaluators with unique challenges for the consideration of conversion projects.
The modern hydrotreating processes typically require that some associated components meet requirements under ASME Section VIII Division 2 and the more rigorous requirements that regulate materials, design, fabrication and inspection of these vessels. In conjunction with the ASME Code Section VIII Division 2 guidelines, the recommended practices of API 934A applies to these components. Due to these more strict requirements, evaluators should carefully consider technical competencies when selecting contracting partners.
Machine corrosion-resistant overlay, base metal buildup
There have been recent developments in machine-applied weld-deposit technology that improve metallurgies in ASME Section VIII Division 2 hydrotreating units and meet acceptable turnaround timeframes. After preparing the existing cladding material, proprietary mechanized gas metal arc welding overlay process becomes ideal for confined-space applications because of the custom automatic proportional torch height control. This feature allows for machines to electronically measure the tip to work distance over 200 times a second in order to ensure uniform deposition thickness and minimal weld dilution. These systems utilize state-of-the-art integral waveform controlled welding power supplies running optimized welding parameters to minimize dilution, reduce spatter, and provide a smooth and consistent weld deposit.
For more information, visit www.azz.com/welding-solutions or call (800) 868-9353.
