Self-Heat Recuperation: Theory and Applications

Since the 1970s, energy saving has contributed to various elements of societies around the world for economic reasons. Recently, energy saving technology has attracted increased interest in many countries as a means to suppress global warming and to reduce the use of fossil fuels. The combustion of fossil fuels for heating produces a large amount of carbon dioxide (CO2), which is the main contributor to global greenhouse gas effects (Eastop & Croft 1990, Kemp 2007). Thus, the reduction of energy consumption for heating is a very important issue. To date, to reduce energy consumption, heat recovery technology such as pinch technology, which exchanges heat between the hot and cold streams in a process, has been applied to thermal processes (Linnhoff et al. 1979, Cerda et al. 1983, Linnhoff et al. 1983, Linnhoff 1993, Linnhoff & Eastwood 1997, Ebrahim & Kawari 2000). A simple example of this technology is the application of a feed-effluent heat exchanger in thermal processes, wherein heat is exchanged between feed (cold) and effluent (hot) streams to recirculate the self-heat of the stream (Seider et al. 2004). To exchange the heat, an additional heat source may be required, depending on the available temperature difference between two streams for heat exchange. The additional heat may be provided by the combustion of fossil fuels, leading to exergy destruction during heat production (Som & Datta 2008). In addition, many energy saving technologies recently developed are only considered on the basis of the first law of thermodynamics, i.e. energy conservation. Hence, process design methods based on these technologies are distinguished by cascading heat utilization.