Predictive model for the determination of the discharge flow in pressure relief valves on steam applications

Abstract

This article presents the development of a predictive model which quantify the flow discharge of steam in safety valves, based on tests conducted with Nitrogen in a test bench. The proposed model was built with experimental data obtained through test bench measurements that meet the requirement of the current ASME / API regulations. Simulations were performed in the CFD tool of the ANSYS® software, which was validated using the experimental data obtained, to increase the sample size within the operating range of the valves and thus reduce the costs of experimentation. These results were related to the variables that influence the phenomenon through a multivariate regression, which yielded an expression capable of predicting the steam flow through the safety valve. The proposed correlation calculates the correction factor to predict the flow discharged by the valve operating in the steam generator and based on the measurement of the Nitrogen discharge flow in the test bench. The reproducibility of the developed model was validated through a Durbin-Watson test for residues, a hypothesis test for the model and a normality test, where the predictive capacity of the correlations was verified.