A process for heat integration in engineering processes is provided in which, in a heat carrier circuit, a heat carrier medium takes up heat from a first process stream in a first heat exchanger and releases it to a refrigeration system. In a refrigerant circuit, a refrigerant is cooled in the refrigeration system and the refrigerant takes up heat from a second process stream in a second heat exchanger or a second process stream is cooled in the refrigeration system. The first process stream is a vapor stream from a thermal separation apparatus, and the temperature of the heat carrier medium is increased by heat supply between egress from the first heat exchanger and ingress into the refrigeration system.