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[Objective] In the inaugural switching operation between Pipelines Q1 and Q2, which were originally used for heated and normaltemperature transmission of crude oil respectively in China, the approach of “transformation while operation” was employed, posing challenges such as complex process flows, demanding engineering implementation, and engagement of numerous offload and injection users. [Methods] To ensure a rational transformation and switching mode with minimal impact on normal production and operation, a comprehensive study was conducted on the hydraulic and thermal systems of these transmission pipelines. This study aimed to evaluate various factors influencing preheating and temperature dropping during commissioning, as well as the pros and cons of different switching modes. Simulation accuracy was checked for the preheating process after transforming Pipeline Q2, originally designed for normaltemperature transmission, into a heated transmission system. These simulation results were then verified with actual engineering data to ensure alignment with the practical requirements. Additionally, valuable field experience was gained from the transformation of Pipeline Q1, originally intended for heated transmission, into a normal-temperature transmission system. Based on these study findings, reasonable suggestions and recommendations were presented for key nodes in switching operations. [Results] The selection of the preheating method should be based on site-specific conditions when transforming in-service normal-temperature oil transmission pipelines into heated transmission systems. For instance, Pipeline Q2 should be treated by heating Russian oil to be transmitted in advance combined with preheating the pipeline with high-temperature Russian oil, aligning the commissioning process with the transmission requirements of Daqing oil.Likewise,appropriate measures should be taken to gradually reduce the temperature of oil products between stations during the transition from the heated to normal-temperature mode.This can be achieved through the quantitative transmission of oil products with a gradually decreasing temperature by batch.To facilitate this,heating stations along the route can be utilized to ensure a gradual temperature drop of the oil products between stations. [Conclusion] The study findings offer valuable insights for commissioning under switching operations of inservice crude oil pipelines.

D-p-hydroxyphenylglycine (D-HPG) is an important intermediate for the synthesis of sweeteners and drugs. An innovative continuous chromatographic process was developed to recover D-HPG from crystallization mother liquor, with the aim of reducing the process cost and improving the quality of D-HPG. The thickening properties of different nanofiltration membranes on mother liquor were investigated by pre-treatment test, and the Applexion NF200 nanofiltration membrane was selected to enrich D-HPG. The separation properties of different resins were analyzed by single column experiment, and the separation degree of Applexion XA945 resin to D-HPG and ammonium sulfate could reach 16. Based on the results, the way of sequential simulated moving bed separation was further studied. The results showed that after separation by the sequential simulated moving bed, the average purity of D-HPG in feeding was increased from 42.2% to 96.3%, and the average yield was 91%. The continuous chromatographic system is a promising method for the recovery of D-HPG from crystallization mother liquor. Compared with the traditional process, the new process not only ensures the total yield of D-HPG, but also greatly reduces the process cost and improves the product quality.

For tunnelling in urban areas, the current sequential excavation (SE) method usually increases the number of temp drifts to achieve better control of surface settlements, which may prolong construction duration. In this case study, a four-drift SE method, termed the suspension-type centre cross diaphragm (S-CRD) method, was proposed and applied to the construction of a large cross-section tunnel in soft ground, where normally the six-drift double-side drift (DSD) method would be adopted. Field monitoring results and statistical data indicated that, in comparison with the six-drift DSD method, the four- drift S-CRD method achieved better control of the surface settlements while improving the efficiency of construction by 30%. The advantages of the S-CRD method, i.e., safe and rapid construction, were eminently clear. Key words: SE method, S-CRD method, large cross-section tunnel, soft ground, field monitoring, 1. Introduction The rapid development of modern cities has accelerated the utilization of underground spaces. In particular, constructing tunnel infrastructure has become a natural choice for densely populated cites to [...]