Design and analysis of amulti‐stageaxial turbine for gasifiedcoal‐waterpower system

Abstract

Efficient coal gasification is critical to energy saving and environmental protection. Based on a power generation cycle of coal gasification in supercritical water, this article develops a design method for its low-pressure turbine component. The working medium is a mixture of gasified water and carbondioxide (H 2 O/CO 2). Preliminary design is combined with an optimization algorithm to get the optimum design parameters. To analyze turbine off-design performance, a quasi-one dimensional (Q1D) analysis method is proposed, and three dimensional CFD (3D CFD) predictions are also conducted. In addition, a property table for computing thermodynamic properties of mixture fluids is adopted. It is not only employed in the preliminary design, but also utilized by Q1D and 3D CFD calculations. Based on the developed procedure, a nine-stage H 2 O/CO 2 axial turbine is finally designed. Results indicate that the designed H 2 O/CO 2 turbine has an efficiency of 89.0% in the preliminary design, but 3D CFD predicts a lower value of 84%. This discrepancy is mainly due to a fact that the Q1D method ignores 3D flow effects because it uses empirical loss models to evaluate the performance. Moreover, both Q1D and 3D CFD numerical simulations prove a good off-design performance of the turbine.

Acid Corrosion Analysis in the Initial Condensation Zone of a H2O/CO2 Turbine

“…The low-pressure part of a supercritical H 2 O/CO 2 steam turbine with nine stages was designed by Zhang et al [29] and is investigated in this study. The design parameters of the turbine are shown in Table 3.…”

“…After checking the figures, the grid with N grid (being about 21 million) was taken for simulations of the supercritical H 2 O/CO 2 turbine. The accuracy of the same CFD method was validated by [29]. The surface roughness of the turbine blades increased gradually with the corrosion process on the blade surfaces.…”

“…The three-dimensional CFD method can be used for flow field simulation and predicting the aerodynamic performance of a turbine. A H 2 O/CO 2 turbine design methodology was developed by Zhang et al [29] and includes an optimal preliminary design method, a quasi-one dimensional (Q1D) performance analysis module, a reliable and efficient property table of the H 2 O/CO 2 mixture and a 3D CFD simulation strategy. Cao [30] adopted a method to predict the performance of compressors with different corrosion degrees whereby different roughness values are added to the surfaces of blades by using a wall function.…”