And since LNG is a global business, both metric and English units are used. LNG is typically measured in volumetric units. When in liquid form, LNG is commonly measured in metric tonnes. But you will sometimes see it measured in the amount of gas that it will provide when converted back to gaseous form. In this case, common units are billions of cubic meters bcm or billions of cubic feet Bcf.
Measurement is the challenge since volume is a function of pressure and temperature. For marine vessels:. Mass measurement provides a standard way to measure LNG. Another issue is that no global quality standard for LNG exists, and energy contents may differ. Arjan recommends that:. This can be measured from a sample of the natural gas obtained using a sample taker. A heat exchanger and then a gas density meter can supply this measurement. LNG typically contains propane, which helps ignite the fuel in the engine.
If the methane number is too low, the propane may ignite early, causing the engine to knock. This will result in damage to an engine and knowing the methane number will help to avoid this. Knowing the LNG gas composition from the purchaser or having a gas chromatograph to measure the components helps in knowing the optimum combustion control strategy.
Within the EU there are regulations for the transfer of fluids. Companies in the EU and other joining countries are obliged to follow these regulations for installations and custody transfer points. Within this annex there are five categories, each having its own accuracy requirements based on difficulty of measurement.
LNG, and all other cryogenic liquids, fall into category 2. Newer LNG plants were being built with larger, more efficient trains, and, in the case of adjoining plants such as in Qatar have shared facilities, thereby minimizing unit costs. Rising demand for steel and nickel, and high demand for engineering resources, are blamed for the reversal in the long-term declining cost trend.
This alarming trend will force project promoters to make increasingly aggressive LNG price forecasts and will undoubtedly result in squeezing of margins, and possibly, uneconomic projects if future prices do not live up to expectations. Rising LNG prices are also encouraging development of gas resources previously considered uneconomic. Smaller and more remote fields could be developed using converted or specially constructed ships that will combine LNG production and storage systems, similar to FPSO production for oil fields.
LNG is usually transported to the gas consumer by specially designed refrigerated ships. The ships operate at low atmospheric pressure unlike LPG carriers, which operate at much higher pressures , transporting the LNG in individual insulated tanks. Insulation around the tanks maintains the temperature of the liquid cargo, keeping the boil-off conversion back to gas to a minimum.
Because most older ships do not have active refrigeration systems onboard, ships use the produced boil-off gas as engine fuel. On a typical voyage, an estimated 0. However, as the LNG short-term and spot trade increases, ships are loading LNG from different plants and discharging their cargoes wherever the prices are best at the time. LNG receiving terminals, also called regasification facilities or regas facilities, receive LNG ships, store the LNG until required, and send out gaseous methane into the local pipeline grid.
The main components of a regas facility are the offloading berths and port facilities, LNG storage tanks, vaporizers to convert the LNG into gaseous phase, and pipeline link to the local gas grid. LNG tankers may also be offloaded offshore, away from congested and shallow ports.
This is accomplished using a floating mooring system similar to that used for oil imports via undersea insulated LNG pipelines to a land-based regas facility. The largest component of receiving terminal capital cost is the vaporizer process equipment.
Vaporizers warm LNG from — Conceptually, vaporizers are relatively simple units in which LNG is pumped through tubular or paneled heat exchangers, allowing the temperature to rise.
Contact with seawater in warmer climates or heated water in colder climates keeps the heat exchangers warm. Large volumes of seawater are kept flowing through the system to avoid ice buildup on the panels.
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