A COMPUTATIONAL, MODULAR APPROACH TO THE SIMULATION OF POWERPLANTS

The paper describes the development, the implementation and the practi cal application of a new modular procedure for the numerical simulatio n of thermal powerplants. The procedure has resulted in a FORTRAN code , named ''CAMEL'' (Italian acronym for ''Modular Elemental Plant Calcu lation), which is also described in detail. The plant -any plant, but application of the procedure is presently limited to thermal powerplan t- is described in terms of three matrices, named the Interconnection matrix IM, the plant matrix PM and the Topographic matrix TM, which co ntain in an orderly fashion all of the design data and the ''topologic al'' description of the plant configuration. The Interconnection matri x is equivalent to a structured list of the flows (of matter and energ y) which are fed to or extracted from any of the ''n'' plant component s; the Plant matrix is a table of the design values of all the fluxes in the plant, and the Topographic matrix is a reference table which al lows the logical location of any component to be found both in PM and in IM. Starting from a set of design input data, CAMEL calculates, com ponent, all the values of the thermodynamic variables of interest whic h do not already appear in PM; more precisely, CAMEL can calculate the numerical value of all the parameters needed to uniquely determine th e thermodynamic and/or energetic state of whatsoever flux in the plant by calling for each component the corresponding routine, which return s the numerical value of all the variables it can calculate at the ''p resent'' stage of the simulation. It is important to underscore that t hese routines can calculate a component not as whole machine but equat ion by equation, i.e., the routine must not necessarily calculate all of the operating parameters of the component at the same stage of the simulation, but only those which can be calculated with the data known at the current stage of the simulation and that are involved in the s ame physical event described by one of the equations included in the s et which pertains to that component. CAMEL can perform, at the user's request, either a single plant simulation or a sensitivity analysis of the behaviour of the plant. At present, CAMEL is only capable of perf orming sensitivity analysis of plants at design conditions and in a li mited number of (steady state) off-design conditions (i.e., the analys is is aimed at the optimization of the design operating conditions of the plant): in principle it is possible to implement a transient compu tation, but this has not yet been done. CAMEL has been implemented for powerplant simulation, but the core has been structured to allow the code to handle with any kind of processor-plant, provided the code's c omponent library is large enough. The paper reports the philosophy of the approach, describes the details of the algorithm, discusses the fl ow chart of the numerical code and presents detailed results for an in dustrial case-study: a combined-cycle power station for electrical gen eration.