Dynamic simulation on cryogenic multi-stream heat exchange processes with multi-node coupling method

doi:10.11949/j.issn.0438-1157.20181120

Abstract

Abstract:

Multi-Stream Heat Exchanger (MSHE) is the core component of gas liquefaction system, its working performance can significantly affect the cooling characteristics and thermal efficiency of system. Based on the principle of two-phase volume node, this article established dynamic simulation method for Mixed-Refrigerant (MR) cryogenic system with a Multi-Node Coupling (MNV) MSHE model. The study results reveal that the heat leak's influence on cooling characteristics of MSHE is negligible during start-up process, while significant and can't negligible in low temperature situation. The liquid-level oscillation in MSHE channel can significantly impact the cooling characteristics, and induce the circulating MR composition shift, cooling capacity and cooling-down rate oscillation in further, which may deteriorate the cooling performance of the MSHE. The results suggest that measures should be taken in design and operation process to avoid the liquid level oscillation phenomenon in MR low-temperature MSHE channels.

摘要：

多股流换热器是气体液化低温系统的核心部件，其工作性能对低温系统的降温特性和热力效率的影响显著。基于气液两相的容积节点原理建立多节点耦合的混合工质低温换热器动态模型及计算方法，对多股流换热器动态降温特性进行研究，重点分析换热器的漏热率和（屯液）液位波动对系统降温特性的影响。研究结果表明漏热对启动过程降温特性影响不大，而在降温至低温区时较为显著。换热器液位波动对系统动态降温特性会有显著影响，低温多股流换热器通道内液位波动会引起循环工质组分、有效制冷量、降温速度的波动，从而造成系统降温速度显著偏离优化工作状态，效率降低。这表明在混合工质低温多股流换热器的设计和操作过程中应尽量采取措施，以避免通道内积液波动现象出现。

CLC Number:

ZHANG Pu, ZHOU Li, GUO Kaihua, CHEN Zhenghua, WANG Weijie. Dynamic simulation on cryogenic multi-stream heat exchange processes with multi-node coupling method[J]. CIESC Journal, 2018, 69(S2): 167-173.

张镨, 周理, 郭开华, 陈正华, 王伟杰. 基于多点耦合的低温多股流换热过程动态模拟[J]. 化工学报, 2018, 69(S2): 167-173.

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