Experimental Verification Analysis of Propane Pre-Cooling and Dual Nitrogen Expansion Liquefaction Process Adaptable for Floating Liquid Natural Gas (FLNG) in South China Sea Deep Water Gas Field

Abstract

Liquefaction process is one of the key technologies of offshore FLNG device and is charged by a few of the company’s patent protection. Due to the special offshore operating environment, the choice of FLNG liquefaction process is different from that of onshore. It is very important that FLNG liquefaction process suitable for the marine environment and the oil and gas properties of the South China Sea. In this paper, the static and dynamic performance of propane pre-cooling and dual nitrogen expansion liquefaction process with independent intellectual property rights have been verified by experiment loop simulation with small scale 2000m3/d and middle scale 20000m3/d. Dynamic simulation experimental measures for liquefying key devices such as cold box placed on the swing experiment platform and propane separation tank and the cold box between difference of liquid level changes, are used to verify offshore adaptability of the liquefaction process. Through the static experiments of a small experimental loop with the scale of 2000m3/d simulation considers the liquefaction rate of 93%, energy consumption 0.42kw.h/m3; Dynamic experimental results through the cold box placed on the swinging platform shows that the heat transfer performance of cold box is not affected when FLNG hull roll wave reached 3.6 degrees. The mid-scale experimental simulation of 20000m3/d show that the liquefaction process has the advantages of simple debugging process, convenient operation, quick shutdown and restart, flexible operation, good adaptability to offshore operating parameters, and can realize 3 sets of refrigeration cycles simulation. The propane pre-cooling and dual nitrogen expansion liquefaction process with independent intellectual property rights through the static and dynamic experiments of small and middle scale experimental loop, is verified to the characteristics of high liquefaction rate, low energy consumption and good offshore adaptability. The liquefaction process with independent intellectual property rights can be used to as one of FLNG facility key technologies to develop offshore gas field and faraway from onshore of the South China Sea.