Nowadays, modern gas supply systems are complex. They consist of gas distribution stations; high-, medium-, and low-pressure gas networks; gas installations; and control points. These systems are designed to provide natural gas to the population, including domestic, industrial, and agricultural consumers. This study is aimed at developing methods for improving the calculation of gas distribution networks. The gas supply system should ensure an uninterrupted and safe gas supply to consumers that is easy to operate and provides the possibility of shutting down its individual elements for preventive, repair, and emergency recovery work. Therefore, this study presents a mathematical calculation method to find the optimal operating conditions for any gas network during the period of seasonal changes in thermal loads. This method demonstrates how the reliability of gas distribution systems and resistance to non-standard critical loads are affected by consumers based on the time of year, month, and day, and external factors such as outdoor temperature. The results in this study show that this method will enable the implementation of tools for testing various management strategies for the gas distribution network.
The rapid growth of liquefied natural gas consumption makes the issues of its transportation more urgent. At present, liquefied natural gas pipeline transportation is carried out only by means of short length process lines. This paper discusses the main features of cryogenic liquids pipeline transportation that obstruct its spread. The proposed model allows to carry out thermal and hydraulic calculations of an underground cryogenic pipeline. The distinctive feature of this model is the fact that it takes into account the changes in basic thermodynamic parameters of cryogenic liquid. The model is based on the Darcy-Weisbach equation and a differential heat transfer equation. In addition, the influence of the Joule-Thomson coefficient inversion on the temperature of the pumping cryogenic liquid was discussed. The comparative analysis of the pipeline construction efficiency made of ultra-high molecular weight polyethylene and AISI 321 steel was conducted. It was found that the use of polymer materials contributes to an increase in the transportation distance. The developed model can be applied for estimation of the transportation parameters change of single-phase fluid flow. The obtained results can be used in initial analysis of the process lines designing and construction.
At present the production of polymer materials is developing intensively, new materials, comparable with steels in their strength properties have recently appeared. In this connection, the analysis of polymer materials applied in the pipe industry has been carried out, and the use of ultra-high molecular weight polyethylene (UHMWPE) is proposed as a structural pipeline material, allowing pipes to operate at cryogenic temperatures. The focal point of the article is the consideration of the fracture mechanisms of those materials and the nature of the change in the mechanical properties of UHMWPE under cryogenic temperatures, also taking into account the creep process. The expression for determining the value of the creep modulus depending on the temperature and operating time was obtained. A method is proposed for conducting initial strength estimation. Moreover, the computer model of stress-strain state of an underground cryogenic polymer pipeline for liquefied natural gas transportation is obtained. The results of simulation depict the potential possibility of using of UHMWPE for the cryogenic pipeline construction
The paper considers the possibility of selecting the optimal diameter of a gas pipeline with a length of more than 1000 km and a capacity of 10 million m3 per year of natural gas using an algorithm developed in the C++ programming language in order to minimize time costs. The results of calculations for three options of pipeline diameters - 820, 1020, 1200 mm are considered to justify the proposed algorithm. The gas pipeline strength in the longitudinal direction was checked for the inadmissibility of plastic deformations and general stability using standard calculation methods laid down in the program. Temperature differences and parameters of the pumped product are taken into account.
The article indicates the importance of thorough preparation of concentrate samples before hydrometallurgical operations; the experiments on studying of the factor of the size of the material are described. The comparative analysis of particle size after conventional and fine grinding is carried out. As obligatory stage of preparation of the crushed concentrate before autoclave leaching, the decarbonization process is studied. On the basis of the conducted experiments, the optimal regime of the autoclave leaching process is revealed, which provides the oxidation degree of sulfide sulfur of the order of 99%.
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