Experimental investigation of the sloshing influence on FLNG liquefaction system

ABSTRACT

With the exploitation of oil and gas resources in the ocean, the application of FLNG is more and more extensive. The FLNG ships will face with sloshing, which will exert an influence on the performance of the system. In order to study the effect of sloshing on the double mixed refrigerant liquefaction process, a sloshing platform of six degrees of freedom is built to perform the sloshing experiment of DMR system. The experimental on yaw, roll and pitch is carried out by measuring the temperature, pressure, flow and pressure difference at key nodes to analyze the effects of three different sloshing forms on the overall liquefaction performance and the equipment. It can be found that sloshing will reduce liquefaction performance and increase power consumption. The sloshing has an adverse effect on the distribution of fluid in the heat exchanger and reduces the heat transfer effect. In addition, the sloshing has a greater impact on the wound tube heat exchanger than the plate fin heat exchanger. The effect of the yaw is negligible and the effect of the roll is biggest. The research results can provide reference and guidance for offshore FLNG production.

KEYWORDS:

• FLNG
• liquefaction system
• sloshing effect
• experimental research
• six degree of freedom
• double mixing refrigerant

Notations

Ta1	=	Temperature of feed gas after plat fin heat exchanger
Ta2	=	Temperature of precooling refrigerant before throttling
Ta3	=	Temperature of precooling refrigerant after throttling
Tb1	=	Temperature of feed gas after wound tube heat exchanger
Tb2	=	Temperature of feed gas before wound tube heat exchanger
Tb3	=	Temperature of cryogenic refrigerant before throttling
Tb4	=	Temperature of cryogenic refrigerant after throttling
Tc	=	Temperature of feed gas after throttling
Pa1	=	Pressure of precooling refrigerant at the outlet of throttling
Pa2	=	Pressure of precooling refrigerant at the inlet of throttling
Pa3	=	Pressure of precooling refrigerant at the outlet of precooling compressor
Pd1	=	Pressure drop of plat fin heat exchanger
Pd2	=	Pressure drop of wound tube heat exchanger
Pb1	=	Pressure of cryogenic gas refrigerant at the outlet of throttling
Pb2	=	Pressure of cryogenic gas refrigerant at the inlet of throttling
Pb3	=	Pressure of cryogenic liquid refrigerant at the outlet of throttling
Pb4	=	Pressure of cryogenic liquid refrigerant at the inlet of throttling
Pc1	=	Pressure of feed gas at the inlet of throttling
Pc2	=	Pressure of feed gas at the outlet of throttling
Q1	=	Flow rate of precooling refrigerant
Q2	=	Flow rate of cryogenic refrigerant
Q3	=	Flow rate of feed gas
$h_f$	=	Resistance loss, m;
$\mathit{\lambda }$	=	Resistance coefficient;
$\mathit{L}$	=	Pipe length, m;
$\mathit{D}$	=	Pipe diameter, m;
$\mathit{\upsilon }$	=	Fluid velocity, m/s;
$\mathit{g}$	=	Acceleration of gravity, m/s2;
$W_1$	=	Power consumption of precooled compressor, kW;
$W_2$	=	Power consumption of cryogenic compressor, kW;
$\mathit{Q}$	=	Feed gas flow rate, Nm3.

Additional information

Funding

This work was supported by the National Key R&D Plan [grant number 2017YFB0903605], National Natural Science Foundation of China [grant number 51606188], the frontier science research project of CAS [grant number QYZDB-SSW-JSC023], Transformational Technologies for Clean Energy and Demonstration, Strategic Priority Research Program of the Chinses Academy of Sciences [grant number XDA21070200].

Notes on contributors

Xueyu Chang

Xueyu Chang, Assistant Engineer, is mainly engaged in liquefied natural gas and turbomachinery.

Yuxing Li

Yuxing Li, Professor, is mainly engaged in LNG and oil and gas gathering and transportation.

Jianlu Zhu

Jianlu Zhu, Ph.D., is mainly engaged in liquefied natural gas and heat transfer research.

Xuehui Zhang

Xuehui Zhang, Ph.D., Senior Engineer, is mainly engaged in residual pressure recovery and turbomachinery.

Wen. Li

Wen. Li, Ph.D., Professor, is mainly engaged in the research of turbomachinery.

Chao. Wang

Chao. Wang, Engineer, is mainly engaged in heat transfer research.

Haisheng Chen

Haisheng Chen, Professor, is mainly engaged in energy storage system and turbomachinery research.

Jie Chen

Jie Chen, Vice Chief Engineer, is mainly engaged in liquefied natural gas (LNG) and offshore FLNG research.

Weiping Zeng

Weiping Zeng, Engineer, is mainly engaged in liquefied natural gas and offshore FLNG research.