Refrigerant storage in LNG production

Abstract

A refrigerant tank (40) holds a hydrocarbon refrigerant (42) used by refrigeration equipment (14) to cool natural gas to about −163° C. to produce LNG (liquefied natural gas) (45). The refrigerant is stored on a floating structure (10) in a way that avoids dangers that would arise if the refrigerant were stored on deck with the refrigeration equipment. A refrigerant container (40) is stored in one of the LNG tanks (20) that holds LNG at about −163° C.

Description

CROSS-REFERENCE[0001]Applicant claims priority from U.S. provisional patent application Ser. No. 60 / 898,858 filed Feb. 1, 2007.BACKGROUND OF THE INVENTION[0002]Natural gas is transported long distances by tankers that carry the natural gas cooled to about −163° C. so it is in a liquid state as LNG (liquefied natural gas) or as LPG (liquefied petroleum gas). The LNG has a volume that is less than 0.2% of the volume of natural gas in a gaseous state (at atmospheric pressure). A recent development in the LNG industry is to liquefy natural gas offshore on board a floating liquefaction structure such as a vessel or barge that is usually more than a kilometer from shore. The floating structure carries refrigeration equipment to cool the natural gas to a liquid state and carries insulated LNG tanks to store the LNG prior to offloading it to a tanker. The LNG tank or tanks lie in the vessel hull primarily below the deck of the vessel. Refrigeration equipment is generally located on the deck...

AI Technical Summary

Benefits of technology

The invention is a floating structure with refrigeration equipment and LNG tanks that have a refrigerant container for storing refrigerant. The refrigerant container holds a large amount of refrigerant, which is used by the refrigeration equipment. The refrigerant container is stored within one of the LNG tanks, which keeps it safe and convenient. The refrigerant includes liquefied gases, such as ethane and propane, which are stored at a temperature of approximately -190°C. The refrigerant container is vented directly into the LNG tank, because any vapor is a proper part of LNG. The invention provides a safer and convenient way to store and use refrigerant in a floating structure.

Problems solved by technology

), the refrigerant is flammable and poses a great danger to the crew in the event of a leak.

Images