采用动态物流模型计算LNG接收站的有效罐容

科学合理地确定LNG储罐罐容及数量配置是LNG接收站前期研究阶段最重要的任务之一,目前国外概念设计与前端工程设计一般用静态经验公式估算法来确定新建LNG接收站项目的LNG储罐罐容,再采用外部第三方或其内部开发的动态数学模型进行核算,基本未考虑用气市场的波动性和调峰需求,估算结果明显低于LNG接收站达到设计负荷工况下的实际需求。为此,引入成熟的物流概念和技术,把握LNG产业链的物流本质,针对LNG接收站储罐的库存物流和LNG运输船到港、卸货的排队物流特性,建立了用于计算LNG接收站储罐罐容及其数量配置的动态数学模型。通过广东某LNG接收站项目实例计算比较可知,该模型具有以下优点:既可确定经济合理的LNG运输船船容及配置、LNG接收站罐容及配置,又可计算出非均匀船期条件下的LNG储罐罐容及所需配置数量,还可动态地掌握LNG储罐库存曲线的变化情况,为现货采办等经营手段提供可靠的决策依据。

Calculation of effective storage capacity of a LNG receiving station by dynamic mathematical modeling

To reasonably determine the storage capacity and the number of LNG tanks is one of the most important issues in the feasibility study of a LNG project. Presently, either the conceptual design (CD) or the Front End Engineering Design (FEED) companies abroad always adopt the static experiential models to estimate the storage capacity. Then they employ the third party or their self developed dynamic model to check the result. As in such cases, the fluctuation of the gas market and the peak shaving are not taken into consideration, the estimated results are obviously lower than the actual demand of a LNG receiving station under the designed load operation condition. By introducing the concept and technology of the experienced supply chains, in combination with the essence of the logistics activities in the LNG supply chain, this paper established a dynamic mathematical modeling to calculate the storage capacity and the number of LNG tanks based on the stock logistics for LNG tanks and queue logistics for the arriving and unloading of LNG ships at the jetty. To prove the validity of this dynamic modeling, a LNG receiving terminal in Guangdong Province was taken as a case study. The result shows that this dynamic modeling is capable of determining the capacity and deployment of LNG carriers and the LNG receiving tanks (even in such an irregular case with uncertain shipping date). Besides, it can also be applied to monitor the changing situation of the LNG tank capacity, and provide credible reference for the decision making on proper dealing modes, such as spot purchase.