LNG接收站贸易交接在线取样技术
Online Sampling Technology Used for LNG Terminal Custody Transfer
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- 引用格式:
-
张,奕,艾绍平,王,浩,安,娜.LNG接收站贸易交接在线取样技术[J].天然气与石油,2015,33(2):0.doi:
Zhang Yi, Ai Shaoping, Wang Hao, An Na.Online Sampling Technology Used for LNG Terminal Custody Transfer[J].Natural Gas and Oil,2015,33(2):0.doi:
- DOI:
- 作者:
- 张 奕 艾绍平 王 浩 安 娜
Zhang Yi, Ai Shaoping, Wang Hao, An Na
- 作者单位:
- 中石油京唐液化天然气有限公司
PetroChina Jing-Tang LNG Co., Ltd.,
- 关键词:
- LNG接收站；计量；在线取样；分馏；过冷度；探头；汽化器；超临界
LNG terminal; Metering; Online sampling; Fractionation; Super cooling; Probe; Vaporizer; Supercritical
- 摘要:
- 为在LNG接收站卸船过程中获得接卸LNG的热值，需在接卸期间进行精确的在线取样，这是准确进行贸易交接的先决条件。通过对贸易交接计量流程和在线取样工艺流程以及在线取样系统的分析，对取样过程的关键工艺技术进行了研究，提出取样系统的控制要求。经过综合研究和分析得出：在线取样应在气质均匀的过渡流状态且卸货速率和压力稳定的全速卸货过程中进行，以保证取样具有代表性；LNG样品进入汽化器前必须保持过冷状态，防止汽化分馏，而经过汽化器需在超临界状态全部充分汽化且不会凝析来保持与原样品组分比例一致，这是取样的关键控制因素，并以实例进行了过冷度计算；整个取样过程中应对关键工艺参数进行实时的密切监控。因此，取样时间段的选择很重要，对取样系统设备性能要求很高。
Accurate online sampling is necessary to obtain LNG heat value during its unloading at LNG terminal and it is the precondition of accurate custody transfer. Analyzed are technological processes of custody transfer metering and online sampling and online sampling system structure, studied is the key technology used in sampling process and proposed are control requirements of sampling system. Analysis and study results show that online sampling shall be completed during full speed unloading process when gas quality transition flow is smooth and unloading rate and pressure are stable so as to ensure the representative of samples. LNG samples shall be kept in super cooled state before being put into the vaporizer in order to prevent gasification and fractionation. All of LNG samples shall be gasified fully and not condensate in supercritical state when passing the vaporizer so as to keep the same components with those of original samples, which is the key controlling factor of sampling. The key parameters shall be closely monitored throughout the whole sampling process. Therefore, selection of sampling time is very important and sampling system shall have good property.
