Harvesting the Potential of CO2 before it is Injected into Geological Reservoirs

To store CO2 in geological reservoirs, expansion valves have been used to intentionally release supercritical CO2 from high-pressure containers at a source point to lower-pressure pipelines and transport to a selected injection site. Using expansion valves, however, has some shortcomings: (i) the fluid potential, in the form of kinetic energy and pressure which can produce mechanical work or electricity, is wasted, and (ii) due to the Joule-Thomson cooling effect, the reduction in the temperature of the released CO2 stream might be so dramatic that it can induce thermal contraction of the injection well causing fracture instability in the storage formation. To avoid these problems, it has been suggested that before injection, CO2, should be heated to a temperature slightly higher than that of the reservoir. However, heating could increase the cost of CO2 injection. This work explores the use of a Tesla Turbine, instead of an expansion valve, to harvest the potential of CO2, in the form of its pressure and kinetics, to generate mechanical work when it is released from a high-pressure container to a lower-pressure transport pipeline. The goal is to avoid throttling losses and to produce useful power because of the expansion process. In addition, due to the friction between the gas and the turbine disks, the expanded gas temperature reduction is not as dramatic as in the case when an expansion valve is used. Thus, as far as CO2 injection is concerned, the need for preheating can be minimized.

A preliminary design method for axisymmetric turbomachinery disks based on topology optimization

The topology optimization can be used to obtain preliminary turbomachinery disk designs which meet strength requirement. In order to eliminate enclosed holes which challenge manufacturing processes and to ensure distinct solid-void interface in the optimal result obtained by the topology optimization, a density distribution function is introduced for each element column in the design domain. Then, a parameter in each function is used to determine the disk’s thickness at corresponding radial position by controlling element densities. Once thicknesses at all radial positions are optimized, the shape of disk is thus determined. In this way, the optimization problem can be simplified by using these parameters as design variables. Illustrative examples are carried out to demonstrate the effectiveness of the proposed method in designing both compressor disks and turbine disks in comparison to the software T-Axis Disk and shape optimization method.

Probabilistic Fracture Mechanics for Mature Service Frame Rotors

Large gas turbine design and service business are challenged with increased demands towards flexible operations, increasing number of start-stop cycles and intermediate cycles. Probabilistic fracture mechanics (PFM) simulation design tools have matured and became robust and reliable. We present a probabilistic re-evaluation of Siemens E-class turbine disks by the combination of probabilistic two-dimensional axisymmetric part analysis of the disk and a novel probabilistic approach for the three-dimensional blade attachment. The first addresses the risk of inherent forging flaws, the latter combines the risk of surface crack initiation, growth and failure. Both models consider the heterogeneous nature of material properties, flaw geometries and detectability. These novel concepts developed at Siemens allow for an optimization of resource usage and safety, as well as the development of new service and inspection concepts for a variety of service frames and classes.

Probabilistic Fracture Mechanics for Mature Service Frame Rotors

Large gas turbine design and service business are challenged with increased demands towards flexible operations, increasing number of start-stop cycles and intermediate cycles. Probabilistic fracture mechanics (PFM) simulation design tools have matured and became robust and reliable. We present a probabilistic re-evaluation of Siemens E-class turbine disks by the combination of probabilistic two-dimensional axisymmetric part analysis of the disk and a novel probabilistic approach for the three-dimensional blade attachment. The first addresses the risk of inherent forging flaws, the latter combines the risk of surface crack initiation, growth and failure. Both models consider the heterogeneous nature of material properties, flaw geometries and detectability. These novel concepts developed at Siemens allow for an optimization of resource usage and safety, as well as the development of new service and inspection concepts for a variety of service frames and classes.

Dynamic Characteristics Analysis and Optimization Design of a Simulated Power Turbine Rotor Based on Finite Element Method

The vibration optimum design for a simulated power turbine rotor without blades on the disk by using an optimization method based on the finite element method is described in this paper. The installation position of the two-stage turbine disks is chosen as design variables under the constraints of feasible regions for the critical speeds of the rotor. The objective functions are to minimize the transient response of the acceleration at the bearings and the amplitude of the disks. Predictions of the dynamic characteristics of the rotor are obtained by using ANSYS code. The optimization problem is solved by using commercial optimization code ISIGHT. The optimum installation position of the two-stage turbine disks is determined after optimization design. Experimental tests under the optimized structure show that the amplitude of the two-stage turbine disks which are recognized as the most concerned optimization objectives are reduced by 59 % and 56 % respectively in comparison with the comparative structure. The encouraging results demonstrate the potential of the presented method as an engineering design tool and also lay a foundation for the design of the real power turbine rotor used in turbo-shaft engine.