LNG接收站次氯酸钠投加量确定及产生装置选择

Sodium hypochlorite dosage determination and generation unit selection of LNG terminal

LNG接收站通常采用海水作为气化LNG的热媒,但实际运行中,却存在海洋微生物滋生、附着管道及设备的风险。因此,LNG接收站通常会在海水取水口处投加次氯酸钠(NaClO),但NaClO投加量及产生装置却是其必须考虑的问题。首先,分析了投加量的影响因素及评价标准,并以大连LNG接收站为例说明投加量的具体确定方法;其次,分析了电解海水制NaClO装置及NaClO溶液直接投加装置,并计算了二者的运行成本;最后,就两种装置的优劣进行对比分析。结果显示,电解海水制NaClO装置具有运行成本低、NaClO即产即用的优点;而NaClO溶液直接投加装置则具有前期投资费用低、装置简单和建造面积小的优点。

LNG terminals usually use seawater as heat medium to gasify LNG.But in the actual operation,there are risks that marine microbes multiply and adhere to pipes and units.Therefore,LNG terminals usually add sodium hypochlorite at the seawater intake,but the dosage and generation units are questions needed to be answered.Firstly,the factors affecting the dosage and its evaluation criteria were analyzed and the dosage determination process was illustrated with Dalian LNG Terminal as a case study.Then,two types of generation units,seawater electrolysis system and sodium hypochlorite solution direct dosing system,were introduced and each running cost was calculated respectively.Finally,the advantages and disadvantages of the two systems were analyzed.From the comparison,seawater electrolysis system had the benefits of lower running costs and could be used immediately after production;on the other hand,sodium hypochlorite solution direct dosing system had the advantages of lower front-end costs,more simple device,and less footprint.