Production of synthetic hydrocarbons

A process for operating a thermal desalination unit comprising:

• adding the first high temperature heat transfer fluid stream and the saline water at ambient temperature to the thermal desalination unit;
• exchanging heat between fluidly segregated 1a) saline water and 2a) first water vapor to produce fluidly segregated 1b) preheated saline water and 2b) first condensed desalinated water, respectively;
• exchanging heat between fluidly segregated 1c) preheated saline water and 2c) first high temperature heat transfer fluid stream to produce fluidly separated 1d) second water vapor and first brine and 2d) first low temperature heat transfer fluid stream;
• exchanging heat between fluidly segregated 1e) preheated saline water and 2e) second water vapor to produce fluidly segregated 1f) first water vapor and second brine and 2f) second condensed desalinated water;
• withdrawing first and second condensed desalinated water as desalinated water product;
• and
• withdrawing first and second brine as a brine effluent stream.

A heat integration system between an electrolysis unit and a thermal desalination unit in an eFuels production system, the heat integration system comprising:

• a) the thermal desalination unit configured to receive seawater and a first amount of thermal energy and to produce a desalinated water stream and a brine effluent stream;
• b) the electrolysis unit configured to receive a demineralized water stream and an amount of electrical energy to produce a hydrogen stream, an oxygen stream, and a second amount of thermal energy and to produce a second high temperature heat transfer fluid stream;
• and
• c) a fluidly segregated piping system containing a heat transfer fluid configured to:
• i) withdraw from the electrolysis unit a first flow of the heat transfer fluid at a first temperature;
• ii) divide the first flow into a second flow and a third flow of the heat transfer fluid;
• iii) add heat to the second flow and deliver the second flow of the heat transfer fluid to the thermal desalination unit at a second temperature, wherein the second temperature is higher than the first temperature;
• iv) withdraw from the thermal desalination unit the second flow of the heat transfer fluid at a third temperature, wherein the third temperature is lower than the second temperature;
• v) join the second flow of the heat transfer fluid from the thermal desalination unit with the third flow of the heat transfer fluid to form a combined flow equivalent to the first flow;
• and
• vi) remove heat from the combined flow and deliver the combined flow of the heat transfer fluid to the electrolyzer at a fourth temperature, wherein the fourth temperature is lower than the third temperature.