GB1429954A - Natural gas - Google Patents

Abstract

1429954 Odorizing natural gas SAN DIEGO GAS & ELECTRIC CO and DUAL FUEL SYSTEMS Inc 26 Sept 1973 [2 Oct 1972] 44976/73 Heading C5E Natural gas is odorized by (a) providing liquid natural gas (LNG), and either (i) (b) forming a mixture of a diluent and a thiophene odorant, (c) introducing the odorant-diluent mixture into the LNG in a required amount; or (ii) (b) forming a solution of a thiophene odorant having a freezing point above the boiling point of LNG with a diluent having a freezing point below the boiling point of LNG, the diluentodorant ratio being such that the odorant is maintained in solution without precipitation upon introduction into the LNG, (c) cooling the odorant-diluent solution to a temperature no lower than a.predetermined minimum temperature above the boiling point of LNG, the predetermined minimum temperature being the temperature corresponding to the minimum temperature at which effective thermal agitation to mix the solution of odorant and diluent and the LNG occurs, and (d) introducing the cooled odorant-diluent solution into the LNG in a required amount. The diluent may be propane and the thiophene may be tetrahydrothiophene 2-methylthiophene, 3-methylthiophene and mixtures thereof, the cooling in (ii) (c) being to a temperature below the boiling point of propane and above that below which effective thermal agitation of the LNG does not occur. The predetermined minimum temperature is -60‹ F. and the solution is cooled to at least - 20‹ F. At least 20 parts by volume diluent may be present per part odorant in the odorantdiluent solution. The LNG and the odorantdiluent solution may be mechanically agitated during step (d), e.g. by injecting the cooled odorant-diluent solution into the LNG under a pressure exceeding that of the LNG, or after step (d).