Conceptual optimisation of utility networks for operational variations – I. Targets and level optimisation
Mavromatis, S.P., Kokossis, A.C.
Chemical Engineering Science, vol.53, no.8, p.1585-1608
Operational variations; Process design; Steam turbine network synthesis; Utility systems
The design of utility networks involves two major tasks: the selection of the steam levels, with respect to their pressure or saturation temperature, and the determination of the configuration of the operating units between the steam levels. Both tasks require models that enable the conversion of the cogeneration potential into shaftwork targets, on the basis of which the profitability of the proposed designs is decided. This paper introduces a new targeting model and procedures to analyse existing design options ahead of design. The turbine hardware model (THM) accounts for the variation of efficiency with the turbine size, load and operating conditions in a simple, yet accurate way. The model is derived by exploiting basic steam turbine principles and engineering knowledge. It is applicable to any type of units and can provide accurate estimates of its performance over the entire operation range. As such, it can be used for setting realistic targets for shaftwork at the early stages of design, as well as for selecting the steam levels that maximise the potential for power cogeneration. The application of the THM is illustrated through a number of examples involving simple and multiple operations, and a comparison is made with a constant efficiency model.