Typical Process Diagram for Small LNG Regasification (Part 2)

As mentioned in part 1, small LNG regasification facility typically consists of LNG unloading facility (which can be flexible hose or marine loading arm), LNG storage tank, LNG sendout pump, ambient air vaporizer, and metering. In part 1 we already discussed about LNG unloading facility and LNG storage tank. In this part I want to share the rest of them.

LNG Sendout Pump

LNG sendout pump is used to increase pressure of LNG before being sent to vaporizer. In LNG facility, there are two most common type of pump: submerged centrifugal pump and reciprocating pump.

Submerged centrifugal pump is used when LNG flowrate is high but the pressure in low to medium. Meanwhile reciprocating pump is used when the flow is low but the pressure is high.

Ambient Air Vaporizer

There are several type of vaporizer used in LNG regasification facility. Among those type of vaporizer, natural draft ambient air vaporizer is considered the most economical. It utilizes ambient air to vaporize LNG.

Ambient air vaporizer is usually installed as two groups of equipment. While one group is operating, the other group is defrosting. Switching between one group and another one is usually every 4-8 hours, however it is actually depend on ambient condition and outlet gas temperature. When gas temperature decreases to certain level, we can adjust it by faster switching of AAV.

At downstream of AAV, temperature transmitter connected to low alarm and interlock of low-low temperature is installed. The function of interlock is to ensure downstream piping from cracking because material used at downstream of AAV is usually carbon steel.

Metering System

After the LNG is vaporized, gas produced is metered in metering system. Metering system is also used for transaction purpose. Depend on requirement, metering system monitor component composition and energy content of the gas.