to derim the interior surfaces of a cryogenic heat exchanger application_number US 69462710 A description reference will now be made in detail to embodiments of the invention one or more examples of which are illustrated in the accompanying drawings each example is provided by way of explanation of the invention not as a limitation of the invention it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention for instance features illustrated or described as part of one embodiment can be used in another embodiment to yield a still further embodiment thus it is intended that the present invention cover such modifications and variations that come within the scope of the appended claims and their equivalents a cascaded lng process uses one or more refrigerant systems for sequentially transferring heat energy from the natural gas stream to the environment where different refrigeration systems may use different refrigerants each refrigeration system functions as a heat pump by removing heat energy from the natural gas stream as the stream is progressively cooled to lower and lower temperatures in so doing the thermal energy removed from the natural gas stream is ultimately rejected pumped to the environment via energy exchange with one or more refrigerants the design of.