Method and system for producing a cooled hydrocarbons stream

The pressure of a mixed refrigerant in a selected point in a mixed refrigerant circuit, which relates to the total number of molecules available in the mixed refrigerant circuit, is used to optimize a cooling process. A real time optimization model is employed to calculate a pressure target value for the pressure in a selected point in the mixed refrigerant circuit. The calculation is based on a plurality of measured variables. The power load is kept below a pre-determined maximum power load and while keeping the discharge temperature below a pre-determined maximum discharge temperature. At least one makeup stream of one of said components is selectively fed to the mixed refrigerant circuit, and/or at least one bleed stream of refrigerant is bled from the mixed refrigerant circuit, whereby decreasing a differential between an actual pressure in said selected point and said pressure target value.