| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for producing high-purity terephthalic acid in excellent energy recovery efficiency by effectively using steam generated by a pressure drop cooling in a crystallization process. <P>SOLUTION: The method for producing high-purity terephthalic acid comprises (I) a process for slurrying crude terephthalic acid by liquid-phase oxidation of para-xylene, (II) a process for forming an aqueous solution of crude terephthalic acid by heating the slurry by a plurality of heat exchangers in stages, (III) a process for hydrogenating the aqueous solution, (IV) a process for crystallizing terephthalic acid by the pressure drop cooling of the obtained aqueous solution by a plurality of crystallization tanks in stages and (V) a process for solid-liquid separation of the obtained slurry. The process (II) comprises at least one of a process for introducing steam generated in the process (IV) to the heat exchangers and heating the slurry and a process for introducing a high-temperature fluid comprising steam generated in the process (IV) and a condensate formed in the heat exchangers to which steam at pressure and temperature higher than those of the steam is introduced to the heat exchangers and heating the crude terephthalic acid slurry. <P>COPYRIGHT: (C)2008,JPO&INPIT |
