Calculation of transmission process parameters for LNG pipeline

The physical parameters of LNG during pipelining can be determined by LKP and its correlation equations. The constant items of simple fluid and reference fluid in LKP equation were respectively obtained through fitting the experimental data of argon and normal octane by Lee-Kesler. In this article, LKP equation expression with contrast density, constant pressure heat capacity expression with calculating states principle (CSP)and the mixture viscosity calculation formula of LNG were given. The "super-cooling" state principle was used to calculate the pipeline transmission process parameters of non-gasified LNG pipeline. The calculation method for hydraulic, thermodynamic parameters of pipe and the thickness of cold insulation layer were also given. Taking the Dalian LNG receiving terminal as an example, if the operational parameters of a 6 km-long pipe with the elevation difference of 48.5 m were calculated, the following results would be obtained: (1)the pressure drop of the pipe was 0.338 MPa, (2)the thickness of cold insulation layer was 0.145 mm, (3)the transmission temperature of LNG was at -154 ℃ when the LNG was pumped to the terminal. Therefore, if transmission pressure were at 1.194 MPa, LNG would be kept liquefied state in the whole pipeline. The transmission feasibility of LNG under "super-cooling" state was also verified.