Process integration exchangers

Polley GT (1993) Heat Exchanger Design and Process Integration, Chem Eng, 8 16. 

Kemp, I.C., Deakin, A.W., 1989. The cascade analysis for energy and process integration of batch processes, Part 1, Chem. Eng. Res. Des., 67 495-509 Kiperstok, A., Sharratt, P.N., 1995. On the optimization of mass exchange networks for the removal of pollutants. Trans. IChemE, 73b 271-277... 

Processing temperatures, heat exchanger network, 13 222 Process integration... 

Product- to-Feed Heat Interchange. Heat exchange is commonly used to cool the product of a thermal process by preheating the feed to that process, thus providing a natural stabilizing, feed forward type of process integration. Product-to-feed interchange is common on reactors as well as distillation (qv) trains. 

Application To produce ammonia from hydrocarbon feedstocks using a high-pressure heat exchange-based steam reforming process integrated with a low-pressure advanced ammonia synthesis process. 

Step 3 is next because the reactor is typically the heart of an industrial process and the methods for heat removal are intrinsically part of the reactor design. So it is usually not optional what degrees of freedom can be used for exothermic reactor control. When the heat generated in an exothermic reactor is used within the process via energy integration, we must ensure that the energy is dissipated and not recycled. Hence we examine process-to-process heat exchangers and... 

Step 3 of our plantwide control design procedure involves two activities. The first is to design the control loops for the removal of heat from exothermic chemical reactors. We dealt with this problem in Chap. 4, where we showed various methods to remove heat from exothermic reactors and how to control the temperature in such reactors. At that point we assumed that the heat was removed directly and permanently from the process (e.g., by cooling water). How-ever. it is wasteful to discard the reactor heat to plant utilities when we need to add heat in other unit operations within the process. Instead, a more efficient alternative is to heat-integrate various parts of the plant by the use of process-to-process heat exchangers. 

Step 3. The open-loop instability of the reactor acts somewhat like a constraint, since closed-loop control of reactor temperature is required. By design, the exothermic reactor heat is removed via cooling water in the reactor and product condenser. We choose to control reactor temperature with reactor cooling water flow because of its direct effect. There are no process-to-process heat exchangers and no heat integration in this process. Disturbances can then be rejected to the plant utility system via cooling water or steam. 

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