دوماهنامه مهندسی شیمی ایران
پیاپی 118 (دی 1400)

Hydrate formation is often undesirable in gas transmission and distribution systems and is often prevented from forming by various methods. In this study, the possibility of interrupting the flow of gas through the formation of hydrates or the formation of ice (controlled) at the desired location pipelines for repairs, the method of doing this, as well as how to resolve it after completion of repairs and safety considerations has been considered and the best approach has been evaluated based on the best or the nearest operational and operational criteria. All experimental data for natural gas are collected and the hydration formation temperature is simulated using artificial neural networks of the RBF model in the software environment of MATLAB. These results are compared with the experimental data, the mean square error for these artificial neural networks are less than optimal. In this study, the effect of the presence of nanomaterials on the formation of natural gas hydrates on simulated temperature and pressure parameters using artificial neural networks RBF (time series) has been empirically derived from valid papers In the following, one of the most practical cases has been studied and analyzed and expanded according to the formulation of mathematical constants and variables to be applied. For the simultaneous formation of hydrate and ice inside the tube, it is necessary to raise the temperature of natural gas from 60°F to 32°F, for this purpose, the cooling fluid of the device is nitrogen liquid at a temperature of -195.79 °C.

The increasing trend of pollutant gases emission into the atmosphere, particularly greenhouse gases, such as carbon dioxide (CO2) and their role in global warming, has led to numerous investigations to separate these gases. For this purpose, the hollow fiber membrane contactor (HFMC) technology, possessing advantages over traditional separation processes, has drawn a great deal of attention. Some of these advantages include consumption of less energy, low footprint, providing high contact area for mass transfer, and easier scale up. Therefore, compared to traditional separation methods, such as chemical absorption in packed columns, adsorption, and cryogenic distillation, HFMC might be considered as a proper alternative for separation of pollutant gases, more specifically CO2, which is the most important greenhouse gas. In this paper, technical characteristics and effective parameters on separation performance of HFMC along with a number of studies conducted by foreign and internal researchers have been investigated and some active companies involving in this field have been also introduced.

In the present study, zinc oxide nanoparticles (ZnO NPs) have been synthesized using hydroalcoholic clove extract and three accelerated heating methods namely, hydrothermal (at 121 °C and 1.5 bar), microwave irradiation (power of 800 W for 3 min) and conventional heating using a heater and stirrer (at 150 °C for 2 h). Characteristics of the  prepared clove extract and synthesized ZnO NPs have been evaluated using GC-MS, XRD and SEM analyses and their antioxidant and antibacterial activities have been measured using DPPH and agar diffusion techniques.   GC-MS analysis indicated that the provided extract had contained two main bioactive compounds of Eugenol and β-caryophyllene, which both of them are natural reductant agents. In order to synthesis ZnO NPs, 4 g of zinc nitrate and 20 mL of the provided clove extract had been mixed together  and after heating the mixture solutions using three different heating methods,the solutions have been placed into the laboratory furnace adjusted at 400°C for 2h to result in pale yellow powder. Obtained results indicated that the synthesized ZnO NPs using microwave, autoclave and heater and stirrer, had particle size of 45, 50 and 52 nm, antioxidant activity of 89, 85 and 80% and methylene blue degradation of 79, 70 and 66%, respectively. Furthermore, results indicated that the synthesized ZnO NPs have high antibacterial activity against both bacteria strains of Escherichia coli and Staphylococcus aerous.