钛合金螺旋盘管原油换热器传热特性研究

Study on Heat Transfer Characteristics of Titanium Alloy Spiral Pipe Crude Oil Heat Exchanger

为满足采油井场井口采出液(原油)冬季加热的特殊技术需求,解决管壳式、板式、套管式等传统形式换热器在相应使用条件下存在的难以承受高压、尺寸及质量大、制造困难、造价高、易腐蚀、流阻大等问题,设计制作了一台液量为25 m3/d的实际井场钛合金螺旋盘管原油换热器,并搭建了相应传热与流阻测试实验装置。开展了多种工质对在多种流速匹配下的传热性能实验,以及壳程防冻液和管程原油的流阻测试实验。结果表明:在壳程为水或防冻液,管程为原油时,壳侧雷诺数应达到7000(对应流速0.32 m/s)以上,管程雷诺数应达到2000(对应流速1.1 m/s)以上,才能获得相对较高的总传热系数;壳程载热介质流速在很宽的范围内流阻都很小,对泵总扬程的影响基本可忽略,壳程流速选择可仅从能量平衡角度考虑;管程原油流动雷诺数在2000~2500之间(对应流速1.1~1.3 m/s),流阻约为50~75 kPa,相当于一般井口回压的3.3%~5.0%,对抽油机的工作基本不会产生影响,此时已获得了较高的总传热系数。基于换热实验数据,对比较接近实验测试结果的一种理论计算模型进行了分析和修正,使其能与实验结果良好吻合。实验结果和修正的计算模型可用于指导钛合金螺旋盘管原油换热器的产品设计、工程应用选型。

To meet the special technical need for produced liquid(crude oil)heating at producing well site in winter,and solve the problems(including difficulties in withstanding high pressure,large size and weight,difficulties in manufacturing,high cost,easy-corrosive nature and high flow resistance under the corresponding service conditions)of traditional heat exchangers such as tube-shell type,plate type and casing type,a titanium alloy spiral pipe crude oil heat exchanger for actual producing well site conditions,with a liquid volume of 25 m3/d,is designed and manufactured,and a corresponding test apparatus for heat transfer and flow resistance is built.We have conducted experiments on heat transfer performance of various working media under different flow rates,as well as flow resistance tests on shell-side antifreeze solution and tube-side crude oil.The result shows that when the shell side is exposed to water or antifreeze solution and the tube side is crude oil,the Reynolds number of the shell side should be above 7000(corresponding flow rate 0.32 m/s)and that of tube side should be above 2000(corresponding flow rate 1.1 m/s)to obtain a relatively high total heat transfer coefficient;The flow resistance of the shell-side heat-carrying medium is small in a wide range,and its impact on the total pump lift height is basically negligible.Energy balance could be regarded as the only respect for the selection of the shell-side flow rate;When the Reynolds number of crude oil flow in the tube side is between 2000 and 2500(corresponding to flow rate 1.1~1.3 m/s),and the flow resistance is about 50~75 kPa which is equivalent to 3.3%~5.0%of the general wellhead back pressure,the operation of the pumping unit can hardly be affected.At this time,a higher total heat transfer coefficient is obtained.Based on the heat exchange experimental data,we have also analyzed and corrected the theoretical calculation model which is more aligned with the experimental test results,so that it can well match the experimental results.The experimental results and corrected calculation model could be used to guide the product design and engineering application selection of the titanium alloy spiral pipe crude oil heat exchanger.