Development And Application Of Drag Reducing Agents For Containing Liquid Natural Gas Pipeline

In view of the environment protection and the pressure of world’s carbon emissions, the natural gas exploitation and consumption had increased sharply.As a result, there were higher requirements for natural gas transportation, how to increase the capacity effectively has become a key in the study of gas transportation, so the DRAs emerged at the right moment.In this paper, we synthetized three kinds of new Gemini DRAs ODU、ODL and MDL, and investigated the optimal synthesis conditions through the orthogonal experiment table. The optimum synthesis condition of ODU was: oleic acid: diethylenetriamine: urea=2:2.2:1(mole ratio). First, oleic acid and a bit more diethylenetriamine reacted in 130℃ for 2.5h, then urea was added and reacted in 140℃ for 3.5h. The optimum synthesis condition of ODL was: lauric acid: diethylenetriamine: phthalic acid =2:2.2:1(mole ratio). First, phthalic acid and diethylenetriamine reacted in 155℃ for 2.5h, then lauric acid was added and reacted in 165℃ for 2.5h. The optimum synthesis condition of MDL was: lauric acid: diethylenetriamine: maleic acid =2:2.2:1(mole ratio). First, maleic acid and diethylenetriamine reacted in 155℃ for 3h, then lauric acid was added and reacted in 170℃ for 3h.Due to the corrosion and drag reduction mechanism have a certain similarity, so we selected the materials which has higher corrosion rate for further drag reduction evalutation. Weight loss measurements and electric polarization curves showed that, for the three kinds of DRAs, the corrosion inhibition rate increased following the addition of inhibiter. The corrosion effect of ODU was best under the same concentration among the three DRAs, which could reach 95% in 200mg·L-1. The corrosion inhibition rate decreased with increase of the temperature. Three kinds of DRAs were single molecular adsorption model on the surface of the steel, and the corrosion kinetics studies showed that three kinds of DRAs could increase the activation energy of the corrosion reaction effectively.SEM showed that three kinds of DRAs could reduce the roughness of the surface of the steel effectively, and ODU worked best. By measuring the adsorption density of three kinds of DRAs on the surface of different steels, it showed that the adsorption density on the surface of different steels was: Q235-A >20# >304, while the adsorption density on the same surface was: ODU>ODL>MDL.