Natural gas mainly consists of methane, inert gas, and some heavy hydrocarbons, such as ethane, propane, and butane etc. which are referred as natural gas liquids (NGL). The distribution pipeline companies and natural gas buyers usually specify their desirable ranges of natural gas components and heating values. These specifications may vary widely with respect to different markets. In U.S., for instance, the relatively low heating value is required for the natural gas. Generally, there are two ways to adjust the heating value: adding inert gas or extract NGL. Since NGL can be feedstock for many chemical processes, it has more economic values than that as part of the natural gas stream. Thus, it would be more desirable to lower heating value via NGL recovery. However, a major concern for building NGL fractionator system is the huge amount of cooling and heating duties requested by the condenser and reboiler.
As known, shale gas as one of the most promising unconventional gases is a raising star in the global energy market. Currently, treated shale gas is usually burnt to generate electricity after simply treatment. However, if NGL recovery could be conducted for shale gas, the overall profit will be significantly increased. The problem about NGL recovery for shale gas is that it has to be liquefied first before sent to the fractionation system, which will require a lot of cold energy.
On the other hand, the liquefied natural gas that shipped to receiving terminals needs re-gasification before distribution. A major concern here is the heating energy consumption because natural gas liquefaction needs a great deal of heating energy. In this work, a new conceptual design of natural gas receiving terminals is proposed, which integrates re-gasification with shale gas liquefaction and NGL recovery. The cold energy from re-gasification could be partly recovered by shale gas liquefaction and NGL fractionators’ condensers. Meanwhile, recovered NGL can be easily transported to nearby chemical plants because natural gas receiving terminals normally are built near chemical industry concentrated coast regions. The optimal design and operation of the proposed receiving terminal are identified via coupling rigorous process simulation and simplified optimization models.
See more of this Group/Topical: Process Development Division