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Polyhydroxyalkanoates (PHA) produced by Bacillus bacteria have potential advantages in medical applications, due to its cell membrane do not contain outer membrane lipopolysaccharide (LPS). However, the PHA accumulation level is far lower than that of Gram-negative bacteria. In this study, an alkali-tolerant Bacillus cereus HBL-AI was screened using Nile Red and Sudan Black B in a Low-Salt LB solid medium at pH 8.0. This strain displayed high PHA accumulation capacity in fed‑batch fermentation with glucose as the carbon source in a 5 L unsterilized fermentor. The highest PHA accumulation reached 12.8 g/L and the extracted product was finally determined as (Poly-β-3-hydroxybutyrate, PHB). It has the potential to be used for large-scale open and continuous fermentation. Furthermore, PHA membrane binding protein (PhaP), PHA regulatory protein (PhaQ and PhaR) derived from HBL-AI were heterologously expressed inE. coli and purified to investigate their application as biosurfactants. The results showed that the emulsification ability and stability of three amphiphilic proteins were higher than those of widely used chemical surfactants. The protein concentration of PhaQ used to form a stable emulsion layer in vegetable oil was the lowest (50 μg/mL), which greatly reduced the amount of protein used in emulsification. This clearly demonstrated that HBL-AI has great potential in the production of PHA without endotoxin, and its PHA binding protein can be well applied as an environmentally friendly biosurfactants.

In order to ensure the safe operation of buried natural gas pipeline (BNGP) under landslide debris flow (LDF), a model is established to investigate the strain characteristic of BNGP. The influence of longitudinal LDF morphology is analyzed for the elliptic deformation rate, tensile and compression strain of BNGP. The results show that the influence area of LDF is about 5 m from the upstream and downstream position of active area, respectively. The peak value of elliptic deformation rate is mainly impacted by the thickness and length of LDF, and will increase linearly with that. The maximum value of axial strains will also increase linearly with length, thickness and breadth of LDF. It will decrease with the angle of mountain slope and depth of BNGP. The fracture failure of BNGP may be occurred at the active area of LDF and upstream position of that. But the local yield or fold failure of BNGP will be occurred at the active area of LDF and downstream position of that. At the same time, a method is proposed to estimate the maximum value of elliptic deformation rate and axial strains of BNGP under longitudinal LDF. The deviations between the prediction results and simulation data are less than ±10%.

Cascade hydropower stations have good regulation and storage capacity and they can be used as a regulatory and compensatory “medium” to compensate for the instability of wind–photovoltaic power generation. This paper presents a short-term multi-objective coordinated dispatching model based on wind–photovoltaic–hydro heterogeneous energy hybrid power generation. The multi-objectives of the model included accepting new energy for power generation to the greatest possible extent, tracing the load curve of the grid with minimum differences, and minimizing the discarded water volume of the cascade reservoirs. To reduce the complexity of the problem, the model was decomposed into two-stage optimization model and solved by using the firefly algorithm. This model was applied to a national-level wind–photovoltaic–hydro complementary power generation base in China. The research results verified the validity of the model and showed that it was feasible to compensate for the wind–photovoltaic power output fluctuation by the cascade hydropower stations and to supply power to the grid by bundling these three power sources. During this process, the cascade hydropower stations certainly made some sacrifices and increased the amount of discarded water. The new operational strategy proposed in this paper can promote the low-carbon power dispatching and optimization of the energy structure.

The safety of pipelines being repaired by local reinforcement methods such as welding a cap or patch is gaining attention. This paper describes experimental and numerical research conducted to assess loading capacity of these local reinforcement pipelines when subjected to internal pressure. Two full-scale hydrotests were performed on pipe sections removed from service. The strain variation and burst pressure were measured, and the strain concentrations and collapse loads were investigated. The results demonstrate that there is small difference between the two repaired pipe sections on the burst pressure. Strain output from both actual tests and finite element analyses shows that both repair methods do result in strain concentrations around the repair site, and that the patch method results in less strain variation and lower stress levels compared to the cap repair method.

An accurate prediction on the failure pressure of line pipe is very important in the engineering design and integrity assessment of oil and gas transmission pipelines. This paper analytically investigates the failure pressure of line pipes with or without corrosion defects, and focus on the high strength steels. Based on von Mises strength failure criterion, a classic strength failure criterion, the failure pressure of end-capped and defect-free pipe p M is theoretically deduced with the strain hardening material. In order to derive a general solution for corrosion defect assessment of high strength pipelines, an extensive series of finite element analyses on various elliptical corrosion defects was performed. Finally, a new formula for predicting the failure pressure of corroded pipe in the material of high strength steels is formulated, based on the FE models and p M , and is validated using 79 groups of full-scale burst test data, which contain the low, middle and high strength pipeline. The results indicated that the proposed formula for predicting the failure pressure is closely matches the experimental data for the high strength steels.

Gathering and transportation pipelines of high sulfur gas field were generally owned with gas-liquid mixed flow, large flow and high velocity turbulent multiphase flow characteristics. Focusing on the gathering system of the Puguang high sulfur gas field, a gas-liquid two-phase erosion risk prediction was carried out based on a flow hydrodynamic numerical model. The shear force was applied to represent erosion characterization of the two-phase turbulent flow. The turbulence intensity was applied to represent characterization of turbulent mass transfer enhancement. Based on the grey relational analysis method and according to online corrosion monitoring data integrated with static corrosion experiment data, the corrosion prediction model of the Puguang gas gathering pipelines was established. The work that was done provided the basis for the transmission system of corrosion monitoring and safety management.

Abstract In this work, the corrosion behavior and mechanical degradation of two types of pipe steel, Inconoy 825 and L360, after two years of high sour environments service in Puguang gas-field were studied. Results demonstrated that a fearful elemental sulfur layer deposited on the inner wall of pipeline, pitting corrosion and hydrogen-induced cracking was observed in L360 pipe. In comparison, no pitting corrosion and hydrogen-induced cracking was found in Inconoy 825 steel pipe due to its excellent resistance to corrosion. Furthermore, mechanical properties (yield strength, impact strength, elongation, hardness, fracture toughness) and stress corrosion cracking were investigated. Results showed that the yield strength decreased obviously and the percentage of elongation increased in Inconoy 825 steel but little change in L360. The analysis a change of the mentioned mechanical characteristics together with the results of the diffusion and tapping of hydrogen of them indicated that the properties degradation of Inconoy 825 pipeline steel after long term service was associated with essential role of hydrogen in these processes. The consequences of sudden failures and severe corrosion of metallic material in the high sour gas-field, which associated with their exposure to H2S/CO2 containing gas, led to the preparation of evaluation tests of pipeline. However, passing evaluation tests cannot guarantee the safety in actual work condition unless the field experience had been at least two years. As the first attempt to exploit high sour gas-field in China, it is anticipated that this work of Puguang provides valuable data and an essential insight into the corrosion and degradation of pipeline steel services in high-sour environmental.