Process Integration Techniques for Cogeneration and Trigeneration Systems

Abstract: The production of various energy outputs and other useful secondary by-products from one or more energy inputs is known as polygeneration. The application of polygeneration schemes implies a high degree of Process Integration. This is particularly the case when various utility services are provided from a single source; for instance, when using a waste stream as fuel, energy can be extracted via combustion; then steam can be raised and used for process heating, power production and even process cooling. When only heating and power are produced for use within the site, the system is referred to as cogeneration; when cooling is additionally produced, the system is referred to as trigeneration. This chapter focuses on trigeneration systems, describes their main components, establishes the criteria for its appropriate selection and looks at the use of Process Integration techniques for the design of such systems in the context of background processes. The design of trigeneration systems requires the development of simple and reliable thermodynamic models for evaluating the thermal performance of prime movers at full and part load. Such models are necessary to evaluate operation in situations where plant throughput changes due to seasonal marked demands.