Influence of Tubular Turbine Runaway for Back Pressure Power Generation on the Stability of Circulating Cooling Water System

Abstract

With the increasing maturity of tubular turbine power generation technology, an increasing number of industrial applications use it to recover the rich back pressure energy of a circulating cooling water system (CCWS). However, the influence of tubular turbine runaway on the stability of CCWS is still unclear. This work combines the one-dimensional (1D) method of characteristics (MOC) with the three-dimensional (3D) computational fluid dynamics (CFD), develops a 1D CCWS and 3D tubular turbine coupling simulation method, and simulates the runaway and runaway shutdown processes of tubular turbine under small flow rate condition and large flow rate condition in the real system. Results show that the main operating parameters of the system slightly change when the tubular turbine transitions from the steady state to the runaway condition. The runner’s radial force substantially increases in the runaway condition of the tubular turbine, and the phenomenon of violent oscillation is observed compared with the steady state. During the shutdown process of the tubular turbine runaway condition, the valves in parallel and series with the faulty turbine adopt a reasonable cooperative control strategy, which allows for a smooth recovery of the system operating pressure to the original steady state conditions.

A Numerical Study on the Performance of a Pumping Station with Bell-Mouth-Based Vertical Pumps during an Accidental Shutdown

“…Also, the range of utilization of the 4-quadrant characteristics is very broad in PAT (Pump as Turbine) applications, from the PAT turbine startup [27][28][29], through the pump-turbine transition [30,31], up to the "S" zone close to the turbine runaway conditions, where the so-called S-instability occurs [32][33][34][35][36][37]. The simulation of pump performance during the accidental shutdown can be found, e.g., in [38], where a large vertical mixed-flow pump with a draft tube is modeled inside the commercial CFD software ANSYS Fluent with the angular momentum acting on the impeller updated in each time step by a User-Defined Function (UDF), or in [39], where the runaway and runaway shutdown processes of the tubular turbine inside the circulating cooling water system are simulated based on the combination of CFD and the method of characteristics (MOC) and also using the Fluent UDF. The process of power failure in the case of the submersible tubular pump is also solved in [40] using the direct combination of the Fluent code and the 6DOF model based on the fourth-order multi-point Adams-Moulton formula.…”

Flow Evolution and Energy Loss Mechanism in Accidental Shutdown Process of a Large Submersible Mixed-Flow Pump System

“…Zhang et al (2013) conducted simulation and experiment for a centrifugal pump shutdown process by establishing a closed pipeline system, and analyzed its transient characteristics and flow field evolution. Wang et al (2022) carried out numerical simulation of a water turbine runaway process based on the CFX platform and developed Fortran programs. Fu et al (2020) simulated the transient flow characteristics of pipeline pump during its outage runaway process based on VOF model in Fluent.…”