气主导盲管内水合物沉积特性实验研究

Experimental investigation on the characteristics of hydrate deposition in gas-dominated deadlegs

关键词:  水合物  气主导  盲管  沉积

Key words:  hydrate  gas-dominated  deadleg  deposition

摘要:

目的 为了研究气主导盲管内水合物的沉积特性,使用专门设计的气主导盲管实验装置开展了一系列水合物管壁沉积实验。方法 实验中,竖直管内的气体在密度差的作用下产生自然对流,进而携带高温水蒸气在竖直管内运移并不断在低温的竖直管壁上冷凝,冷凝水最终与气体反应形成管壁水合物沉积层。结果 实验中竖直管内存在水合物沉积层生长最快、厚度最大且最容易形成堵塞的危险位置,管壁水合物沉积层存在厚度和表观体积减小的现象。根据水合物在形成过程中传质和传热条件的不同,竖直管内管壁水合物沉积层从上到下存在6种不同形态。结论 实验过程中,管壁水合物沉积层的生长速率会逐渐降低,这主要是由管壁水合物沉积层具有的“隔热”作用导致的。该研究结果可为深水流动安全保障盲管水合物防治技术的发展提供理论支撑。 

Abstract:

Objective In order to investigate the characteristics of hydrate deposition in gas-dominated deadlegs, a series of experiments on hydrate deposition were conducted in a specially designed gas-dominated deadleg setup. Methods During the experiments, natural convection happened on and the gas in the deadleg under the action of density difference, further induced the transportation of the high-temperature vapour inside the deadleg and the condensation of the vapour on the cold pipe wall. As a result, the condensed water eventually reacted with the gas and formed hydrate deposits on the pipe wall. Results In experiments, there existed a dangerous position in the deadleg where the hydrate deposits grew fastest, had the largest thickness and was most likely to form blockage. Moreover, the thickness and apparent volume of the hydrate deposits gradually decreased in the late stage of the experiments. According to the different mass and heat transfer conditions during the formation of hydrates, there existed six different hydrate deposit morphologies in the deadleg from top to bottom. Conclusion sDuring the experiment, the growth rate of the hydrate deposits gradually decreased, which was mainly caused by the “insulation effect” of the hydrate deposits. The conclusions of this work can provide a guidance for the development of hydrate management strategy in deepwater deadlegs.