极地深层热水钻回水软管伴热功率数值模拟研究

Numerical simulation study on heat tracing power of return‑water hose of deep hot‑water drill in polar regions

极地深层热水钻通过高温高压热水融冰钻进,主要用于快速钻穿冰盖后向其中下放科学监测仪器或获取冰下环境样品。回水腔是深层热水钻重要的组成部分。钻进后的融水上返到回水腔后,通过潜水泵抽吸,经回水软管返回地表。由于极地冰层温度很低,加之深层热水钻回水软管较长,这导致回水软管内的融水在上返过程中存在被冻结的风险。因此,在回水软管内铺设具备电加热功能的伴热电缆,对避免回水软管内融水的冻结以及深层热水钻的稳定运行具有重要意义。目前,尚没有对回水软管所需伴热功率的研究。为此,本文首先对回水软管可能面临的正常工况、停钻工况、干烧工况和解冻工况进行了分析,然后基于COMSOL Multiphysics 6.0软件建立了4种工况下伴热功率的数值模拟方法,主要对回水软管伴热功能的运行功率、运行时间和安全功率上限进行了研究。研究结果给出了回水软管伴热功能在4种工况下的运行策略,为回水软管伴热电缆的设计提供了参考。

Deep hot-water drills in polar regions are used to melt ice by means of high-temperature and high-pressure hot water and are mainly used for rapidly drilling through the ice cap and then lowering scientific monitoring instruments or obtaining samples of the under-ice environment into it.The return-water cavity is an important part of the deep hot-water drill.After drilling,the meltwater is returned to the return-water cavity,pumped by submersible pumps,and returned to the surface through the return water hose.Due to the very low temperature of the polar regions ice and the long return hose of the deep hot-water drill,this leads to the risk of the meltwater inside the return hose being frozen during the upward return process.Therefore,laying heat tracing cables with electric heating function in the return water hose is of great significance to avoid freezing of meltwater in the return hose and stable operation of the deep hot-water drill.At present,there is no research on the required heat tracing power of return water hose.For this reason,this paper firstly analyses the normal working condition,drilling stop condition,dry burning condition and thawing condition that the return water hose may face,and then establishes the numerical simulation method of heat tracing power in four working conditions based on the COMSOL Multiphysics 6.0 software,and mainly investigates the operating power,operating time and upper limit of the safe power of the heat tracing function of the return water hose.The results of the study give the operation strategy of the return water hose heat tracing function under the four working conditions,thus providing a certain reference for the design of the return water hose heat tracing cable.