Due to the similarity of the routing between HVDC transmission lines and buried pipelines, the local pipelines inevitably enter the HVDC transmission interference zone. In order to study the law of interference and mitigation of HVDC grounding electrode on buried pipeline, boundary element software was used to calculate the effectiveness of various mitigation methods including anti-corrosion coating, the distance between the pipeline and the grounding electrode, insulating joints and zinc ribbon. The results indicated that the smaller the coating breakdown factor was, the more concentrated the interference current was , and the higher the local corrosion risk was. After installing the insulating joints, the strongest interfered section of pipe was alleviated, while the interference of the other section of pipe was aggravated. The protection range of the zinc ribbon was equivalent to the length of the zinc ribbon. Finally, the paper put forward the comprehensive protection measures which included insulating joints, cathodic protection and zinc ribbon.

The influence of different catalysts on product distribution of residue hydrotreating in an autoclave with Tahe atmospheric residue (THAR) and Saudi Arabia light crude oil vacuum residue (ALVR) was studied. The results show that the catalyst activity and selectivity can be evaluated by the cracking conversion for unit coking (x1/xcoke) or the ratio of the cracking conversion to the unit condensation (x1/x2). It is consistent to the traditional understanding of residue hydrotreating. The catalysts influenced product distribution by providing active hydrogen atom to inhibit cracking of macromolecular radicals. There is different performance to inhibit coke formation in residue hydrotreating for different catalysts. The inhibition condensation sequence of catalysts is B>C>A and the maximum difference of the ratio of the cracking conversion to the unit condensation can reach 4.3. The influence of catalysts on residue hydrotreating was not only related to content and species of active metals, but also to the atomic ratio of hydrogenating component and surface structure of catalyst.

The asphaltene structure and composition changes pre-and post hydrotreating of residue with different asphaltene contents were researched by 1H-NMR, elemental analysis and molecular weight determination, et al. The results show that the molecular weight, H/C, σ, w(HAU)/ w(C), w(Hα), w(Hβ), w(Hγ) and substituted aromatic-carbon ratio of asphaltene decreased after hydrotreating; but aromatic-carbon ratio, w(HA), protonic aromatic-carbon ratio increased. All above factors show that the condensation degree of asphaltene after hydrotreating is increased and asphaltene is dealkylation in residue hydrotreating. Sulfur in asphaltene decreased but nitrogen increased. The aromatic ring and naphthene ring of hydrotreated asphaltene increase with the increase of asphaltene content in feedstock. The aromatic ring numbers of hydrotreated asphaltene even more than that of original asphaltene. Asphaltene react in the forms of structure units in residue hydrotreating. The reaction mechanism of asphaltene in hydrotreating is free radical reaction and carbonium ion reaction.