Heat balance of chemical production system is not only the basic element for maintain the production process and its operation, but also has a very important value for scientific, engineering and economic research. This article is mainly focus on heat energy production and consumption of production system for using catalytic oxidation method (o-xylene and air) method to produce phthalic anhydride (phthalic anhydride). Analysising and accounting system-wide network of distribution and utilization of steam; of major energy-using equipment, a brief account and the corresponding analysis. Proposed to improve or adjust the relevant process parameters or control aspects of the proposal or the measures, particularly for major energy-consuming processes such as distillation, heat recovery and other related technology and equipment were part of accounting, and pointed out ways to improve energy use or way. So that the conclusions and guidance has strong practical significance. Also take into account the general production of chemicals (endothermic and exothermic type) process energy channels or follow the guidelines of the discussion. Chemical processes in general have a certain energy saving guide.
Key words: chemical energy of phthalic anhydride production process heat balance of chemical energy use