HEAT EXCHANGERS DESIGN FOR THE REGASIFICATION SYSTEM OF THE LNG TERMINAL WITH ANNUAL CAPACITY OF 5 BILLION M3

Abstract

The paper is devoted to the important scientific and technical problem of development of the modern and high-efficient storage and regasification liquefied natural gas terminal. The design, calculated performance and mass-dimensional parameters of heat exchangers and pumping equipment for the regasification system of the LNG terminal with annual capacity of 5 billion m³ at the northern Black Sea coast conditions are presented. The regasification system provides evaporation and superheating of liquefied natural gas to meet the given parameters of evaporated gas at the inlet of the main pipeline. The composition of the system includes heat exchangers: reboilers to evaporate the liquefied gas and superheaters to get the necessary temperature of evaporated gas. The seawater is suggested as the source of heat for evaporation and superheating of the natural gas, with the pumping station is to be used for pumping the water through heat exchangers. To make a sufficient investigation the change in seawater temperature throughout the season is had to be taken into account. Peculiarities of the annual maintenance of reboilers, superheaters and pumps due to change in the seawater temperature have been shown in the paper. A shell-and-tube heat exchanger type with multiple reverse flow of LNG is suggested to use for the reboiler. The superheater is designed as the finned-tube heat exchanger with multiple cross-flow of seawater. The set of limits was applied to the calculations among them are: the temperature drop of seawater on the heat exchanger is less then 3 °C (±1) and the maximum permissible speed of seawater in heat exchanger is 2 m/s. According to the calculations, the necessary amount of reboilers and superheaters is 10 items each type with the dimensions of reboiler about 1,25×1,4×4,1 m and superheater about 3,6×1,55×1,55 m. Seawater flow adjustment during the year, corresponding to its temperature, permits to meat ecological limits and to provide the regasification of the daily capacity of liquefied natural gas at the pressure of 4 MPa and outlet temperature greater than 2 ºC as it is shown by dint of mathematical simulation. The range of seawater flow is 6700…9350 kg/s, the necessary pumping station power – 4300 kWt