Patent ID: 7935844

Claim:
A process for energy recovery during the production of aromatic carboxylic acids by liquid phase oxidation of aromatic hydrocarbons wherein reaction overhead vapor comprising reaction solvent and water is formed, the process comprising the steps of: a) performing a high efficiency separation on the reaction overhead vapor to form at least a high pressure gaseous overhead stream comprising water and organic impurities; b) recovering heat energy from the high pressure gaseous overhead stream by exchanging heat with a heat sink material such that a condensate comprising from about 20 wt % to about 60 wt % of the water present in the high pressure gaseous overhead stream is formed and a high pressure off-gas comprising about 40 to about 80 wt % of the water present in the high pressure gaseous overhead stream remains uncondensed, and temperature or pressure of the heat sink material is increased; c) expanding high pressure off-gas remaining uncondensed from step (b) comprising about 40 to about 80 wt % of the water present in the high pressure gaseous overhead stream to recover energy in the form of work from the high pressure off-gas; and (d) directing heat sink material increased in temperature or pressure in step (b) to another step of the process for heating or to use outside the process.