Process composition analysis via online mass spectrometry

A method for liquefied natural gas (LNG) liquefaction, the method comprising:

• receiving a gas feed stream;
• condensing the gas feed stream into an LNG product stream;
• removing nitrogen from the LNG product stream using a nitrogen rejection unit to produce a final LNG product stream;
• determining nitrogen content by performing a compositional analysis to generate mass spectrometry data of a plurality of process samples using mass spectrometry without gas chromatography applied to the plurality of process samples, the compositional analysis is performed on the plurality of process samples simultaneously, the plurality of process samples are taken from the final LNG product stream output by the nitrogen rejection unit and from an intermediate stream at a location before the nitrogen rejection unit;
• determining a nitrogen removal rate of the nitrogen rejection unit by comparing the nitrogen content of the plurality of process samples taken from the final LNG product stream output by the nitrogen rejection unit and from the intermediate stream at the location before the nitrogen rejection unit;
• and
• controlling, via control logic, at least one of one or more LNG facility parameters of an LNG facility or one or more operating parameters of the nitrogen rejection unit based on changes in the nitrogen removal rate.

A system for liquefied natural gas (LNG) liquefaction, the system comprising:

• an LNG facility operable to condense a gas feed stream received at the LNG facility into a LNG product stream;
• a nitrogen rejection unit coupled with the LNG facility, the nitrogen rejection unit operable to remove nitrogen from the LNG product stream to produce and output a final LNG product stream;
• an analyzer coupled with the LNG facility and operable to obtain mass spectrometry data for a plurality of process samples simultaneously, the analyzer including a mass spectrometer without a gas chromatograph, the plurality of process samples taken from the final LNG product stream output by the nitrogen rejection unit and from an intermediate stream at a location before the nitrogen rejection unit, the analyzer determining a nitrogen removal rate of the nitrogen rejection unit by comparing a nitrogen content of the plurality of process samples taken from the final LNG product stream output by the nitrogen rejection unit and from the intermediate stream at the location before the nitrogen rejection unit;
• and
• control logic operable to control at least one of one or more LNG facility parameters of the LNG facility or one or more operating parameters of the nitrogen rejection unit based on changes in the nitrogen removal rate.