Method and system for controlling refrigerant composition in case of gas tube leaks in a heat exchanger

A method for cooling a gaseous process stream, the method comprises the steps of:

• providing a heat exchanger unit for cooling a gaseous process stream, wherein the heat exchanger unit comprises a heat exchanger vessel comprising a plurality of process stream conduits, and a first and second refrigerant inlets connected to a plurality of refrigerant conduits;
• receiving the gaseous process stream in the plurality of process stream conduits and discharging a cooled process stream from the plurality of process stream conduits,
• receiving at least part of a pre-cooled mixed refrigerant stream in the plurality of refrigerant conduits and discharging a cooled mixed refrigerant stream from the plurality of refrigerant conduits;
• receiving at least a portion of the cooled mixed refrigerant stream at an expansion device of the heat exchanger unit and discharging a further cooled mixed refrigerant stream from the expansion device,
• providing the further cooled mixed refrigerant stream to at least one of a third refrigerant inlet and a fourth refrigerant inlet of the heat exchanger vessel to provide cooling to the plurality of process stream conduits and to the plurality of refrigerant conduits;
• receiving, by the refrigerant bleed vessel of the heat exchanger unit, a first refrigerant split-off stream split off from the cooled mixed refrigerant stream upstream to the expansion device,
• receiving, by the refrigerant bleed vessel, a second refrigerant split-off stream split off from the pre-cooled mixed refrigerant stream upstream to the first or second refrigerant inlet;
• discharging a bleed stream from a bleed outlet of the refrigerant bleed vessel;
• and
• discharging a recycle stream from a recycle outlet of the refrigerant bleed vessel, the recycle outlet being fluidly connected to at least one of the third refrigerant inlet and the fourth refrigerant inlet of the heat exchanger vessel.