Modeling of a Steam Turbine Including Partial Arc Admission for Use in a Process Simulation Software Environment

Abstract

A dynamic process model of a steam turbine, including partial arc admission operation, is presented. Models were made for the first stage and last stage, with the middle stages assumed to have a constant pressure ratio and efficiency. A condenser model is also pre sented. The paper discusses the function and importance of the steam turbine's entrance design and the first stage. The results for steam turbines with a partial arc entrance are shown and compare well with experimental data available in the literature; in particular, the "valve loop" behavior as the steam flow rate is reduced. This is important to model correctly since it significantly influences the downstream state variables of the steam, and thus the characteristic of the entire steam turbine, e.g., state conditions at extractions, overall turbine flow, and condenser behavior. The importance of the last stage (the stage just upstream of the condenser) in determining the overall flow rate and exhaust condi tions to the condenser is described and shown via results.

Development of a Dynamic Model and Control System for Load-Following Studies of Supercritical Pulverized Coal Power Plants

“…The leading stage model was considered separately for two reasons: capturing the change in the leading stage efficiency under extremely nonlinear property changes and considering the control setups for fixed-pressure operation [27]. For fixed-pressure operation, separate governing valves are used in the control of separate arcs of admission into the turbine.…”

“…The efficiency, η is , of the leading stage is then calculated using Equations (3) and (4). The equations used for this model are adapted from the work of Liese [27].…”

“…The modeling of the final turbine stage is important since this stage typically operates under a choked flow condition, and it has different performance characteristics than other stages. In addition, due to condensation in this stage under typical operating conditions, the stage efficiency calculation needs to be modified [27]. The Stodola equation (Equation 10) is considered to represent the flow through this stage in the presence of condensation.…”

“…The power produced by the condensing stage is shown by Equation 15as a function of the real enthalpy drop accounting for the presence of moisture. Here, these equations are adapted from Liese [27], as follows:…”

Development of a Dynamic Model and Control System for Load-Following Operation of Supercritical Pulverized Coal Power Plants

“…Three separate ST models are considered to capture the operating characteristics of the various stages of the ST. As a part of SCPC dynamic model development, following models were developed (Sarda et al, 2018) by modifying the ST model developed by Liese (Liese, 2014). After the IP turbines there are auxiliary extractions connected to various reboilers and a single turbine for auxiliary equipment, and the steam goes to the LP section that comprises of five stages, with two extractions to FWHs 5 and 6, after stages 1 and 2, respectively.…”