Advanced Materials Research Vols. 860-863

Abstract: Gas turbine blade is the key components of generator which using natural gas as the power source. The airflow channel on the gas turbine blade has an important effect on the blade life and the power generation efficiency. Diamond-nickel composite plated grinding needle was usually used for the airflow channel finish. The process of the diamond-nickel composite plated grinding needle was introduced in this paper. Monolayer of the ~60μm diamond was first embedded in 12μm~15μm nickel layer, then followed with 25μm~30μm thicker nickel layer plated to hold the diamond tightly. The results show that, the coating adhesion was affected by the bath pH and the roughness of the needle original surface. The grinding needle manufactured in optimized process was tested with MICROMOT 50/E drill grinder at the speed of 8000rpm, the results showed that, 5-7 holes were drilled on the glass with thickness of 1.5mm; the drilling speed was 1.5mm/min.

Abstract: Natural gas has been one of the most important kinds of vehicle fuel since the discovery of abundant shale gas storage. Operating costs of diesel engine can be reduced by replacing diesel with diesel-CNG dual fuel. The present contribution is mainly about the electronic control system of diesel-CNG dual fuel engine. Hardware and software of the electronic control system were designed. Two control strategies named equivalent power control strategy and diesel-saving control strategy were put forward for different control targets. Furthermore, these two strategies were testified by experiments conducted on engine test bench. Results show that average natural gas replacement could up to 70%. Comparing with diesel engine, fuel consumption of diesel-CNG dual fuel engine can be reduced significantly and the power increases slightly also. Both power and economy performances of the engine are improved.

Abstract: The advantages and basic structure of hydraulic free-piston engine (HFPE) were presented. And the operation principle of a single piston compression-ignition HFPE was analyzed. Based on the basic theory of thermodynamics, hydraulic fluid mechanics and dynamics, the system simulation model for a single-piston compression-ignition HFPE was established in the environment of MATLAB/SIMULINK. The simulation results, which accord with the related literature data, indicate that the asymmetric characteristics of piston motion in the entire cycle are very obvious, the compression stroke duration is longer than the expansion stroke, the time at around the top dead center (TDC) is short. The piston assembly motion is a process when the energy balance is fulfilled, and some factors must be taken into account for design optimization, such as the piston assembly mass, compression accumulator pressure, fuel injection timing and fuel injection quantity.

Abstract: The experiments of the economy performance and emissions of diesel engine fueled with ethanol-n butanol-diesel were performed on a dual-cylinder direct injection diesel engine. The results show that without modification on the engine, while the mixed proportion of ethanol getting larger, the equivalent brake specific fuel consumption decreases and effective thermal efficiency increases when the diesel engine work on medium and high loads condition, NO_X emissions and smoke decreased obviously. But the smoke increased when the proportion of ethanol is 20%. And the results also indicate that it is beneficial for decreasing the smoke and NO_X emissions to reduce suitably fuel supply advance angle when the diesel engine fueled with blend fuel mixed high proportion of ethanol.

Abstract: A thorough investigation on the effect of a 320MW steam turbine rotor notch fillet radius on thermal and mechanical stresses during start up is presented. The approach consists of a shape design and analysis procedure which incorporates a finite element model. The finite element model is used to characterize the radius of the rotor notch fillet for ensuring the designed thermal and mechanical stress state/pattern and associated deflection during start-up. The results indicate that the notch fillet radius r has significant impact on the total stress of the rotor, in particular on thermal stress. It is determined that the thermal stress is decreased as the notch fillet radius r increases to a critical value. However, the thermal stress becomes saturated as the radius is increased to values larger than the critical value. The results also indicate that the rotor notch fillet radius has little effect on the deflection of the rotor during start-up. This investigation could be very useful to designers for construction of the design guidelines for steam turbine rotors.

Abstract: The simulation of the reheat condensing steam turbine model that BPA and integrated power system stability calculation procedure given, has a large deviation with the actual experimental data. This model does not consider the regenerative steam extraction module, thus ignoring the storage effect of the regenerative steam extraction module. By analyzing the principles of reheat condensing steam turbines thermal process, based on the real turbine structure, establish multi-stage regenerative steam extraction model. Through dynamic simulation of the model was analyzed and compared with the actual data showed good results. Improved model is more realistic, more suitable for grid stability calculations.

Abstract: The current determination of stagnant rate cannot eliminate the dynamic effects, especially the change rate of speed. Consider the problem of the current determination of stagnant rate, this work presents one determination method based on adaptive chatter algorithm .Simulation shows it can eliminate the impact of dynamics effectively. The method achieves the measurement online due to the signal of chatter can adapt to the dead zone of servo system. At last, the selection of the signal frequency is discussed.

Abstract: The jam fault diagnosis of slide valve oil motive has great significance on the safe and stable operation of steam turbine. As limited data available from DEH, the jam fault is difficultly diagnosed directly by DEH data. This paper defines insensitivity to represent the level of the jam fault of slide valve oil motive system. Through the simulation and research of the jam fault features of the slide valve oil motive, the relationship between the rate of change of the input signal and the insensitivity of the jam fault diagnosis is be found . Then jam fault diagnosis strategy based on DEH data was put forward and it shows good results with verification by the actual data.

Abstract: This article introduces the definition of delay rate in turbine electro-hydraulic control system and its significance in practical applications, and builds the simulation model to measure it. By introducing and analyzing the principal of current domestic delay rate measuring method that uses uplink and downlink ramp signal, it can be found that this kind of determination is affected by the speed largely, and simulation experiments show its validity. Aiming at solving problems of this method, a measuring method of static delay rate based on the frequency step disturbance has been put forward and simulated.

Abstract: Traditional condition monitoring methods are not suitable for the nonlinear operation parameters and time-variable operation conditions. We propose an independent component analysis method based on sliding window statistics (SSWICA). This method uses statistics in sliding windows of parameters as input samples, then uses a N-step forward sliding window ICA method to modeling. Then we monitor the operating state of the equipments by observing whether the SPE index of real-time parameters exceeds the control limits. SSWICA is applied to condition monitoring of condenser in 600MW unit, comparing with traditional ICA monitoring methods based on sliding window. The results show SSWICA can accurately reflect current operating state and related changes of condensers state parameters, recognize steady, unsteady and fault conditions effectively. It is valuable for engineering practice and suitable for the application to equipments condition monitoring in power plant.