| With the rapid development of the global economy, natural gas is playing an increasingly important role in the modern energy structure. As the main mode of natural gas transportation, natural gas pipeline construction develops with the high speed because of the great demand of natural gas. As a result, how to effectively reduce the wall roughness of gas pipeline, reduce the pressure loss in the pipeline transportation, and achieve the goal of drag reduction is a hot research issue in the natural gas transportation field.According to the drag-reducing mechanism of the natural gas DRAs, two kinds of mercapto-triazole compounds were designed and synthesized. In the compounding natural gas DRAs, two kinds of mercapto-triazole compounds synthesized in laboratory were used as film-forming agents, and phosphate was used as film-forming synergic agents. The property of two compounding system was studied and researched.The influences of several reaction conditions on the synthesis process of mercapto-triazole compounds were analyzed, and the best reacting conditions of PABMT were as following:the pH value is about 3; the dosage ratio of intermediate product PAMT and benzaldehyde is 1:1; reaction time is about 60 minutes. At the same time, the best reacting conditions of PASMT were also obtained:the pH value is about 3; the dosage ratio of intermediate product PAMT and salicylaldehyde is 0.9:1; reaction time is about 60 minutes.With the help of infrared-spectrum and X-ray photoelectron spectroscopy (XPS) analysis, the elements and structure of two film-forming agents were researched. The result shows that film-forming agents are made up of carbon, nitrogen, sulfur and oxygen elements. There are triazole ring and thiol group in the molecules of film-forming agents.The adsorbed films of two compounding natural gas DRAs were prepared on the surface of iron sheet and iron electrode. By scanning electronic microscope (SEM) and electrochemical impedance spectroscopy (EIS) analysis, the film-forming property of compounding natural gas DRAs was reflected. Both two kinds of compounding natural gas DRAs were adsorbed firmly on the iron surface to form an elastic film, and the roughness of the iron surface decreased obviously. After marinated in the solution of compounding natural gas DRAs, the capacitance arc of iron electrode became larger, and charge transfer on the iron electrode surface became more difficult. The results showed that both two compounding natural gas DRAs performed well film-forming property on the iron surface, and the compounding natural gas DRAs based on PASMT performed much better film-forming property.The drag-reducing property was tested in the natural gas DRAs laboratory evaluation system, and the optimum working condition was also provided. When the components of the compounding system were used alone, they performed rare drag-reducing properties. However, when they were compounded with a certain proportion, the compounding system showed much better drag-reduction property. There was excellent synergistic drag-reducing effect between two components of the compounding system. Compared with the compounding natural gas DRAs based on PABMT, the compounding natural gas DRAs based on PASMT performed much better drag-reducing property, which was up to 9.4%. As a result, the optimum working conditions of two kinds of compounding natural gas DRAs were obtained: the film-forming agent weighs five gram, the film-forming synergic agent was one hundred milliliters and the solvent is eight hundred milliliters. What's more, the natural gas transportation temperature played an important role in the drag-reducing effect. The drag-reducing property of the compounding system was decreased obviously when they were used at low temperature. |
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