Utilizing heat sinks for further energy efficiency improvement in multiple heat integrated five-column methanol distillation scheme

Abstract Although the potential of energy efficiency improvement of methanol distillation is largely reduced, heats are still in lack of recovery for discharging along with liquid products at embarrassing temperatures. Instead of routinely elevating certain stream temperatures to make a heat source at the cost of other energies. This work suggests an opposite strategy to utilize heat sinks to obtain temperature differences enough for heat recovery. In our former publication, compositions of lower boiling points are observed at the medium pressure column and the atmospheric column, whence make heat sinks available. This facilitates process adjustments for higher heat efficiency: (1) transit the medium column into a preceding atmospheric column, (2) pressured column top vapor distributes heat for thermal integration between bottoms of the light ends column and the preceding atmospheric column, (3) steam condensate from all the reboilers take over 90% heat supply to the former atmospheric column. Compared with the prototype, these changes knock down 31.85% specific stream consumption from 0.919 to 0.697 kg (steam)/kg (methanol). Exemplified by the evolution of five-column methanol distillations, the heat sinks strategy adds another train of thought to create heat transfer drive when utilizing low temperature heat for thermal coupling within chemical plant installations.