Abstract
Chemical process comprises multiple units that are linked together through process streams. Though it has the advantages of operation independence and flexibility, it will lead to considerable energy consumption and equipment investment. Existing studies have placed more stress on the heat integration and steam reduction for single unit. However, it is rarely optimized for the linking stream. In this study, local heat exchanger network was optimized based on the proposed hot direct feed/discharge strategy. On the whole, the heat integration consists of the integrations in the hot direct feed/discharge region and the downstream process. This strategy was capable of regulating the temperature distribution and improving the freedom of energy comprehensive optimization. The heat integration for downstream process was re-optimized under the principle of minimum steam consumption, where minimum steam flowrate was determined using the latent heat and the sensible heat of steam simultaneously. As revealed from the results, the optimal design decreased hot utility and cold utility by 32.24 MW and 29.14 MW. The steam condensate contributed 6.0 MW heat, which was provided by the latent heat of steam originally. Furthermore, as demonstrated from techno-economic analysis, an annual increment of 3.09 M$ benefit was achieved in a 0.6 Mt/y coal-to-olefins (CTO) process.
NSTL
Elsevier