液化天然气深冷-膜蒸馏海水淡化系统集成与分析

doi:10.11949/0438-1157.20201553

摘要/Abstract

摘要：

提出了一种PRICO天然气液化-膜蒸馏（MD）海水淡化系统集成方法，利用PRICO过程压缩机出口的余热驱动MD海水淡化。采用Aspen Plus和GAMS建立了集成系统的数学模型，综合考虑系统的结构、物流物性、设备规模、操作参数等系统设计问题，分析不同设计下系统的投资、能耗、运行费用以及MD单位产水成本。模型应用于一个处理量为1 kmol/s的PRICO天然气液化系统与MD集成的案例研究。计算结果表明，单位产水成本最小时，系统产水成本为1.98 USD/m³，淡水产量为5.78 m³/h，与反渗透等海水淡化技术相比，MD在经济性方面具有较强的竞争力。

关键词: 过程系统, 集成, 液化天然气, 膜蒸馏, 海水淡化

Abstract:

An integrated system of PRICO natural gas liquefaction-membrane distillation (MD) seawater desalination is proposed. The system utilizes the waste heat from compressor outlet of the PRICO process to drive MD seawater desalination. A mathematical model of the integrated system is formulated using Aspen Plus and GAMS. The model simultaneously considers the system structure, streams properties, equipment sizing, operating parameters, and other system design variables. The model is capable of optimizing the system design that achieves the optimal investment costs, energy consumption, operating costs, and MD unit water production costs with different system configurations. A case study of a PRICO process with processing capacity of 1 kmol/s integrated with MD process is investigated. Computational results show that the optimal system design is able to achieve a minimum water production cost of 1.98 USD/m³ with a freshwater production rate of 5.78 m³/h, demonstrating that MD is economically competitive compared with reverse osmosis and other seawater desalination technologies.

Key words: process system, integration, LNG, membrane distillation, seawater desalination

中图分类号:

TQ 028.8

徐健玮, 梁颖宗, 罗向龙, 陈健勇, 杨智, 陈颖. 液化天然气深冷-膜蒸馏海水淡化系统集成与分析[J]. 化工学报, 2021, 72(S1): 437-444.

XU Jianwei, LIANG Yingzong, LUO Xianglong, CHEN Jianyong, YANG Zhi, CHEN Ying. Integration and analysis of PRICO-membrane distillation seawater desalination system[J]. CIESC Journal, 2021, 72(S1): 437-444.

图/表 9

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设计参数	数值
天然气处理量	1 kmol/s
天然气压力	5.5 MPa
气态天然气温度	25℃
液化天然气温度	-155℃
制冷剂流量	2.4 kmol/s
冷凝器出口温度	25℃
节流阀入口温度	-155℃
节流阀出口温度	-167℃
冷海水温度	20℃
淡水产品温度	25℃
热海水温度	70℃
冷淡水温度	30℃
膜热侧流速	2 m/s
膜冷侧流速	2 m/s
最小换热温差	5℃

设计参数	数值
天然气处理量	1 kmol/s
天然气压力	5.5 MPa
气态天然气温度	25℃
液化天然气温度	-155℃
制冷剂流量	2.4 kmol/s
冷凝器出口温度	25℃
节流阀入口温度	-155℃
节流阀出口温度	-167℃
冷海水温度	20℃
淡水产品温度	25℃
热海水温度	70℃
冷淡水温度	30℃
膜热侧流速	2 m/s
膜冷侧流速	2 m/s
最小换热温差	5℃

物质	摩尔分数
物质	N₂	CH₄	C₂H₄	C₃H₈	C₄H₁₀-1
天然气	2.8%	89.8%	5.5%	1.88%	0.1%
混合制冷剂	12.53%	19.09%	32.96%	—	35.42%

物质	摩尔分数
物质	N₂	CH₄	C₂H₄	C₃H₈	C₄H₁₀-1
天然气	2.8%	89.8%	5.5%	1.88%	0.1%
混合制冷剂	12.53%	19.09%	32.96%	—	35.42%

项目	数值
电价P_e/（USD/(kW·h)）	0.13
清洁周期T_cl/d	5
清洁费用C_cl/( USD /次)	1.17
保养费C_m/( USD /a)	0.025(c_hx+c_pump)
保险费C_i/( USD /a)	0.01c_ca