Overhauled and Regenerated Steam Turbine: Reconditioning Process and Application

Abstract

The present work aims to analyze the economic convenience of using a reconditioned steam turbine within a waste-to-energy plant for municipal solid waste. First, the methodology for the evaluation of the functional conditions of the disused steam turbine will be identified through a complete revision of the turbine itself, paying attention to components subject to greater wear. The considered steam turbine is a disused and malfunctioning machine considered “a disposal.” The overhaul operations necessary for reconditioning are preceded by an analysis of the typical failures of steam turbines that allows to identify the components with the highest incidence of failures and to evaluate the frequency of occurrence and severity of the damage. The analysis of all possible fault chains and the maintenance history of the steam turbine are aimed at defining the inspection methodology to be carried out on the various components. Once the functionality has been verified and the necessary reconditioning operations of the steam turbine have been completed, the possibility of its reuse in a waste-to-energy plant for municipal solid waste will be analyzed. Through appropriate market analysis simulation, the actual possibility of using the reconditioned steam turbine within an existing plant used as a reference plant will be evaluated. The economic evaluations and the calculation of the return time must provide for a comparison of the purchase costs of a revised steam turbine compared to a new one, considering the revenues related to the sale of the electricity produced, the thermal power generated, and the revenues related to waste treatment. In the present work, the authors wanted to underline the importance of considering the waste-to-energy of municipal solid waste as an added value rather than as a mere cost aimed only at the inertization process. In addition, it can be underlined that the use of a reconditioned steam turbine also guarantees economic convenience since the payback time is equal to two years.