Thermal integration of trigeneration systems

Trigeneration can be considered as a special case of the application of cogeneration systems where a fraction of the shaft work or residual heat is used for running a refrigeration system. This work focuses on trigeneration schemes where a gas turbine is used as a prime mover for power production and cooling is generated by a typical compression–refrigeration system. In most applications, a gas turbine will meet either the process power requirements or the heating needs, but it is unlikely that both would be satisfied simultaneously in the most efficient manner. The selection of the gas turbine that minimizes the heat losses to the ambient while supplying the required power can be readily accomplished by superimposing the turbine exhaust gas temperature profile to the process streams profile in a T vs enthalpy curve. This is because the maximum overall efficiency depends on the process heat and power demands and on the shape of the heat demand profile of the process. The use of the thermodynamic model helps to simulate the main components of the system and permits a fast and interactive way to design the optimum trigeneration scheme using the performance data of commercial gas turbines.