Technical Discussion on incorporating methanol transport in product oil pipelines

Objective Utilizing existing product oil pipelines for additional methanol transport can enhance hydrogen and methanol delivery while addressing the issue of insufficient throughput in product oil pipelines. However, China has not yet developed a comprehensive technological system for this purpose.

Methods The basic properties of methanol and relevant specifications and standards were reviewed to discuss the batch design for incorporating methanol transport in product oil pipelines. Precautions for the adjacent transportation of methanol with diesel and gasoline were analyzed. The impact of additional methanol transport on mixed oil volumes was examined, and key aspects of isolation fluid selection and application were identified. With a focus on quality management for additional methanol transport in product oil pipelines, process technologies such as batch interface monitoring and tracking, methanol/gasoline and methanol/diesel mixed oil cutting, and mixed oil treatment were elaborated on.

Results The adjacent batch transportation of methanol with diesel and gasoline respectively has its own advantages. A feasible batch design for additional methanol transport in product oil pipelines can be established by comparing pipeline oil transportation, oil consumption, and pipeline characteristics, while giving special focus on the control of oil mixing. If isolation fluid is employed, its selection should be based on a comprehensive analysis of the feasibility of the isolation process, oil quality before and after treatment, cost, and reliability. Online density meters, optical interface meters, and online batch interface tracking technologies can effectively monitor and track the interface in the adjacent batch transportation of methanol with diesel and gasoline. Boiling range and flash point were recommended as criteria for methanol/gasoline and methanol/diesel mixed oil cutting. To maintain oil quality and simplify mixed oil treatment, the three types of mixed oil (methanol/gasoline, methanol/diesel, and gasoline/diesel) should be received and stored separately for each batch.

Conclusion Transporting additional methanol through product oil pipelines is technically feasible. However, future research is required on the flow characteristics of the mixed oil segment between methanol and diesel, the diffusion characteristics of the mixed oil, the mixed oil characteristics at the batch interface between water-containing methanol and gasoline/diesel, and the calculation model for mixed oil during the batch transportation of methanol with gasoline and diesel. This research aims to provide technical support for the operation and management of additional methanol transport through product oil pipelines.