Process and system for dehydrating a product stream in ethanol production

A method for dehydrating a product stream in ethanol production, the method comprising:

• distilling a feed mixture including ethanol and water with one or more distillation units to form a distillation unit bottom stream and a vaporous overhead stream;
• contacting a molecular sieve unit with a byproduct stream comprising at least a portion of the vaporous overhead stream, thereby forming a product stream and a regenerate stream;
• contacting the regenerate stream with a separation system comprising a first stripper column and a membrane, thereby forming a first stripper column bottom stream, a permeate and a retentate;
• directing at least a portion of the first stripper column bottom stream to the one or more distillation units;
• directing at least a portion of the distillation unit bottom stream to a plurality of evaporators;
• directing at least a portion of the product stream to the plurality of evaporators, wherein the plurality of evaporators comprise at least a first evaporator and a second evaporator connected without any intervening evaporators therebetween;
• and
• forming a vegetal steam at each of the plurality of evaporators, wherein the vegetal steam formed by the first evaporator is directed from the first evaporator to the second evaporator.

A system for dehydrating a product stream in ethanol production, the system comprising:

• one or more distillation units in fluid communication with a feed source such that the one or more distillation units receive a feed mixture including ethanol and water, to form a distillation unit bottom stream and a vaporous overhead stream;
• a molecular sieve unit in fluid communication with a byproduct stream comprising at least a portion of the vaporous overhead stream, the molecular sieve unit configured to form a product stream and a regenerate stream;
• a separation system comprising a stripper column and a membrane, the separation system in fluid communication with the regenerate stream, thereby forming a permeate and a retentate, wherein the stripper column is in fluid communication with the one or more distillation units;
• and
• a plurality of evaporators arranged to include at least one selected from a first-effect evaporator, a second-effect evaporator, a third-effect evaporator, a fourth-effect evaporator, a fifth-effect evaporator, a sixth-effect evaporator, a seventh-effect evaporator, and an eighth-effect evaporator, the plurality of evaporators in fluid communication with the product stream and at least a portion of the distillation unit bottom stream, wherein the plurality of evaporators comprise at least a first evaporator and a second evaporator connected without any intervening evaporators therebetween, wherein each of the plurality of evaporators is configured to form a vegetal steam, and wherein the vegetal steam formed by the first evaporator is directed from the first evaporator to the second evaporator.