| 摘要 |
[20] A process for the production of a selected quantity of ethane as a component of a production inventory of mixed refrigerant for an LNG production plant prior to start-up of 5 the LNG production plant is described. The process comprises the steps of: a) circulating a pre-cooled gas through the liquefaction facility to produce a pre-cooled liquefaction stream; b) directing a bypass stream of dry sweet scrubbed gas through the light mixed refrigerant circuit of the pre-cooled liquefaction facility at a first mass flow rate to fill the pre-cooled liquefaction facility with the bypass stream; c) running one or more of the 10 compressors in the mixed refrigerant circuit to compress the bypass stream of dry sweet scrubbed gas and produce a pressurised bypass gas stream; d) cooling the pressurised bypass gas stream using the propane refrigeration circuit to produce a cooled pressurised bypass gas stream; e) circulating the cooled pressurised bypass gas stream through the light mixed refrigerant circuit of the main heat exchanger whereby the cooled pressurised 15 bypass gas is cooled as it expands across an expansion valve into the shell side circuit of the main heat exchanger; f) repeating step e) to progressively cool the cooled pressurised bypass stream to form a fully condensed cooled liquid bypass stream; g) evaporating the cooled liquid bypass stream in the shell side circuit of the main heat exchanger to produce a first fraction rich in nitrogen and methane and a second fraction rich in ethane, propane, 20 butane and the heavy hydrocarbons; h) flaring a mass flow rate of the first fraction from the cold end of the main heat exchanger; i) adjusting a mass flow rate of the bypass stream of step b) to compensate for the mass flow rate of the first fraction being flared in step h); j) directing the second fraction to flow out of the warm end of the shell side circuit into the bypass stream being fed to the mixed refrigerant circuit in step to produce an ethane 25 saturated pressurized bypass stream; and, k) cooling the ethane-saturated pressurized bypass stream in the propane refrigerant circuit to produce a condensed heavy mixed refrigerant stream containing liquid ethane for storage in a buffer storage vessel. |
