TARGETING FOR FURNACE SYSTEMS USING PINCH ANALYSIS

An important feature of pinch analysis is its ability to set performance targets for utility consumption for any given process prior to detailed design. However, due to certain limitations in the established concepts, targeting is generally limited to the simpler utility systems such as multiple steam levels or a combination of flue gas and steam. Several new concepts are introduced for the representation of more complex utility and process systems, the most important of which is called the balanced grand composite curves. These concepts enhance the user's understanding of the thermal interactions between a utility system and its associated process, through the use of separate process and utility grand composite curves. They also greatly simplify mixed utility targeting. In the particular case where a furnace with air preheat is used to heat a process, they lead to the development of a simple noniterative procedure to target those furnace operating conditions corresponding to minimum fuel firing. The procedure can also be extended to target more complex multiple utility systems.