Steam Turbine System Research Articles

Simulation of Turbine-Generator

This study involved mathematical modeling of turbine generator simulator (TGS) and speed governing system for Fast Breeder Reactor (FBR). All steam turbine system utilize governor controlled valves at the inlet to the turbine to control the steam flow. The previously developed FBR and Pressurized water reactors (PWR) mathematical models (by author) [1] were connected to the same Turbine-generator model and controlled by the same method of control. Then a comparison between the dynamic performance transient response of FBR and PWR controlled plants were considered in two cases, load demand perturbation and reactivity perturbations. The steam chest and inlet piping to the turbine cylinder introduce delays between valve movement and change in the steam flow. The results show that the model is capable of simulating the dynamic transient response for FBR in two cases, load demand perturbation and reactivity perturbations.

Numerical analysis on utilizing excess steam for electricity production in cruise ships

Marine sector has a significant contribution to the global greenhouse gas emissions and energy usage. Despite that the energy efficiency of ship engines has been increased drastically and the usage of new type of fuels such as LNG has reduced the emissions, significant improvements in the energy efficiency of ship energy systems could be still achieved by the more effective usage of different heat streams. In this study, the potential for producing electric power from excess steam of large cruise ships is investigated. The analysis is carried out for annual operational profiles of case cruise ships and the excess steam utilization is studied by means of 0.5 MW–2 MW scale steam turbine system and a combination of steam turbine and low temperature ORC system. A notable potential in utilizing the excess steam into electricity production was identified. It was observed that due to the high variations in the ship operation, the steam turbine design power and off-design performance have a significant impact on the electrical energy production. In the studied case cruise ships, steam turbine having a low condensing temperature or a combination of steam turbine and low temperature ORC reached the highest annual electric energy production potential, ranging from 3920 MWh/a to 5310 MWh/a.

Integrated Reverse Engineering Strategy for Large-Scale Mechanical Systems: Application to a Steam Turbine Rotor

An integrated reverse engineering methodology is proposed for a large-scale fully operational steam turbine rotor, considering issues related to the development of the CAD and FE model and the application of robust and effective computational finite element model updating techniques based on experimental modal analysis procedures. First, using an integrated reverse engineering strategy, the digital shape of the three sections of a steam turbine rotor was developed and the final parametric CAD model was created. The finite element model of the turbine was developed using tetrahedral solid elements. Due to complex geometry of the structure, the developed model consists of about fifty-five million DOFs. The identification of modal characteristics of the frame is based on acceleration time histories, which are obtained through an experimental investigation of its dynamic response in a support-free state by imposing impulsive loading. Experimentally identified modal modes and modal frequencies compared to the FE model predicted ones constitute the actual measure of fit. CMA-ES optimization algorithm is then implemented in order to finely tune material parameters, such as modulus of elasticity and density, in order to best match experi-mental and numerical data. Direct comparison of the numerical and experimental data verified the reliability and accuracy of the methodology applied. The identified finite element model is repre-sentative of the initial structural condition of the turbine and is used to develop a simplified finite element model, which then used for the turbine rotordynamic analysis. Accumulated knowledge of the dynamic behavior of the specific steam turbine system, could be implemented in order to eval-uate stability or instability states, fatigue growth in the turbine blades, changes in the damping of the bearing system and perform necessary scheduled optimal and cost-effective maintenance strategies. Additionally, upon a series of scheduled experimental data collection, a permanent output-only vibration SHM system could be installed and even a proper dynamic balancing could be investigated and designed.

A generic algorithm of sustainability (GAS) function for industrial complex steam turbine and utility system optimisation

The GAS-function methodology is introduced in this paper in order to identify the sustainability objective function for optimisation of multiple interconnected complex steam turbines and utility network (ICSTUN) systems. Also, the complex steam turbine was modelled based on induction machine operation which enhances its performance. The boiler models were identified as the sustainability objective function which was further investigated under given operating constraints for optimisation of the ICSTUN system. The validated results show that relative error between field operation and simulation data were less than 1% on average, which is acceptable for engineering applications. The optimisation results indicate that contrary to previous authors' results and by comparing with actual field operational data information, coal flow rates for total site utility system of this investigated ICSTUN can be significantly reduced. It was therefore concluded that a significant reduction in the coal flow rate amounts is practicable in order to significantly reduce operating costs as well as the environmental and social issues associated with utilising fossil-fuels, while still satisfying the demand-side management objectives for the plant.

Molten carbonate fuel cell (MCFC)-based hybrid propulsion systems for a liquefied hydrogen tanker

This study proposes a molten carbonate fuel cell (MCFC)-based hybrid propulsion system for a liquefied hydrogen tanker. This system consists of a molten carbonate fuel cell and a bottoming cycle. Gas turbine and steam turbine systems are considered for recovering heat from fuel cell exhaust gases. The MCFC generates a considerable propulsion power, and the turbomachinery generates the remainder of the power. The hybrid systems are evaluated regarding system efficiency, economic feasibility, and exhaust emissions. The MCFC with a gas turbine has higher system efficiency than that with a steam turbine. The air compressor consumes substantial power and should be mechanically connected to the gas turbine. Although fuel cell-based systems are less economical than other propulsion systems, they may satisfy the environmental regulations. When the ship is at berth, the MCFC systems can be utilized as distributed generation that is connected to the onshore-power grid.

Energy, Exergy and Economic Feasibility Analyses of a 60 MW Conventional Steam Power Plant Integrated with Parabolic Trough Solar Collectors Using Nanofluids

The present study focuses on the detailed technical and cost-effective feasibility analyses of a 60 MWe steam power plant integrated with parabolic trough solar collectors. Aluminum oxide (Al2O3) nanoparticles are mixed with thermal oil to be used as a heat transfer fluid in the collector loops. The electric power is generated using steam Rankine cycle. For this purpose, the steam turbine of 60 MWe production capability of Teknecik power plant located in Northern Cyprus has been analyzed and an integrated solar steam turbine system is presented which generates electric power. Detailed energy and exergy assessment of the solar thermal plant is carried out. The important parameters are examined including overall energy and exergy efficiencies, exergy destruction rate and system performance by varying direct normal irradiation (DNI), mass flow rate of the collector, ambient and inlet temperatures. Furthermore, thermal power available from the solar field at various solar multiples is assessed, and levelized energy cost has been calculated. Results show that turbines are the main source of exergy destruction (63855 kW) followed by feedwater heaters and boiler. Overall energetic and exergetic efficiencies of the system are observed to be 22.64 and 23.83%, respectively. The integration of PTC system with conventional plant results in a reduction in fuel consumption which significantly brings down the CO2 emissions by almost 33%.

Fuzzy Arithmetical Modeling of a Steam Turbine and a Boiler System

The steam turbine and a boiler are important components of a power generation plant. Improved effciency of a power plant leads to increase of energy production and less waste. In this paper, a model of the power plant as a multivariable system using fuzzy arithmetic which is based on the Transformation Method (TM) is presented. The analytical solution is used to evaluate the state space model. The TM is then used to quantify the in uence of each parameter and their gain factors are calculated to allow estimation of relative measures of uncertainty. The method is applied to a boiler and a steam turbine systems for simulation, analysis and indication of TM's efficiency. The efficiency of TM is presented in this paper.

Aquadest Production System as Steam Turbine Bottom Cycle I: Influence of Pressure of Cooling Water Tank and Pinch Point Temperature Difference of Condenser

The condenser heat from the steam turbine system is discharged into the environment in a way that is likely to damage the environment. This paper simulates a system that produces aquadest with throttled 10% water of condenser output to the cooling water tank with vacuum pressure so as to produce water vapor. This water vapor is condensed in a cooling machine to produce aquadest. The cold water coming out of the cooling water tank is mixed with cooling water from the sea so the temperature is lower causing the condenser output water to be lower temperature (more environmentally friendly). This simulation varies the pressure of cooling water tanks and Pinch Points Temperature Difference (PPTD) of condenser. From the simulation it is found that the higher the pressure of the cooling water tank causes Specific Aquadest Production (SAP), and Energy Consumtion (EC) is getting smaller. The smaller PPTD leads to Specific Aquadest Production (SAP), Specific Energy Consumtion (SEC) and Energy Consumtion (EC) getting smaller. This simulation has the best result that is able to produce aquadest as much as 0.0133 [kg/s], increase the efficiency of steam power plant by 0.21%, and lower condenser water temperature by 0.9 °C.

Thermo-ecological performance analysis of a double-reheat Rankine cycle steam turbine system (RCSTS) with open and close feed water heaters

Thermo-ecological performance analysis of a double-reheat Rankine cycle steam turbine system (RCSTS) with open and close feed water heaters

Thermo-ecological performance analysis of a double-reheat Rankine cycle steam turbine system (RCSTS) with open and close feed water heaters

This study presents the exergetic and thermo-ecological performance optimisation of a Rankine cycle steam turbine system (RCSTS) consisting of three turbines, one open feed water heater (OFWH) and two closed feed water heaters (CFWHs). In this study, different performance characteristics such as effective power, effective power density, exergy efficiency, exergy destruction and ecological coefficient of performance (ECOP) are used to investigate and optimise the system performance. The effects of condenser pressure, OFWH pressure and reheat pressures on the performance characteristics of the system have been examined by considering the irreversibilities and system properties. The results showed that the component pressures considerably affect the system performance. Therefore, they should be optimised to obtain maximum performance characteristics.

Thermodynamic analyses of a solar-based combined cycle integrated with electrolyzer for hydrogen production

In the current study, a combined steam and gas turbine system integrated with solar system is studied thermodynamically. In addition, an electrolyzer is added to the integrated system for hydrogen production which makes the current system more environmental friendly and sustainable. This system is then evaluated by employing thermodynamic analysis to obtain both energetic and exergetic efficiencies. The parametric studies are also conducted to investigate the effects of varying operating conditions and state properties on both energy and exergy efficiencies. The present results show that while gas turbine can generate 312 MW directly, 151.72 MW power is generated by steam turbine using solar collectors and exhausted gases recovered from the gas turbine. Furthermore, by adding electrolyzer to the integrated system, a total of 131.3 g/s (472.68 kg/h) hydrogen is generated by using excess electricity which leads to more sustainability system.

Bending fault evaluation for the HP-IP rotor system of the nuclear steam turbine based on the dynamic model

With considering the unbalance mass-fluid film bearings-rotor elements, a dynamics model for the nuclear half-speed 1000 MW saturated steam turbine with No. Dongfang HN1089 is constructed. By solving of the Reynolds Equation and the dynamics model, the oil pressure distribution and dynamic coefficients of the fluid film bearings, and the unbalance response of the rotor, are obtained. The method for evaluating the bending fault based on the dynamics model is proposed, in which the bending parameter is transformed as the unbalance mass. A case on the bending fault evaluation for HN1089 is carried out. The results show that the response sensitivity of HN1089 on the unbalance mass is about 1/6 that of the thermal power units with the same capacity (1000 MW); and it is difficult to decrease the excited response from the bending fault even to add the maximum unbalance mass. In actual, the removing stress in the partial zone and turning method are applied to deal with the HP-IP rotor bending fault, and the response of the repaired rotor is 0.033 m by the actual field test. The results show the model and the method for evaluating the bending fault are accurate and reasonable, which will provide the important theoretical guide for fast and accurately dealing with such bending fault in the steam turbine rotor system.

Development and Application of an Engineering Simulator for HTR-PM Using THERMIX/BLAST and vPower

Different from most current commercial nuclear power plants, the High-Temperature gas-cooled Reactor Pebble-bed Module (HTR-PM) power plant consists of two reactor modules connected to a common steam turbine system that will bring a special coupling effect between the two reactor modules. An engineering simulator of the HTR-PM plant was developed by embedding the THERMIX/BLAST code into the vPower simulation platform. Two sets of nuclear steam supply systems of HTR-PM, including two reactors, two steam generators, two helium blowers, and the helium flow ducts, were simulated by two THERMIX/BLAST code modules, respectively. The entire secondary loop system was simulated using intrinsic models of the vPower simulation platform. The vPower platform connects and synchronizes the two THERMIX/BLAST modules, as well as the simulation module for the secondary loop system. The engineering simulator was applied to simulate the behavior of HTR-PM under steady-state operation, startup and shutdown processes, and accident conditions. The coupling effect during the condition conversion process and the thermal characteristics under accident conditions of HTR-PM were analyzed by the engineering simulator.

Technical assessment of the Biomass Integrated Gasification/Gas Turbine Combined Cycle (BIG/GTCC) incorporation in the sugarcane industry

Biomass Integrated Gasifier/Gas Turbine Combined Cycle (BIG/GTCC) systems in the sugarcane industry, are capable to produce more electricity per unit of biomass consumed than the conventional Condensing Extraction Steam Turbine (CEST) systems. A technical analysis of the introduction of BIG/GTCC technology in the sugarcane industry for electricity and heat generation, using wet sugarcane bagasse as fuel, was conducted. For sugar plants, with large steam requirements, the implementation of the “pure” BIG/GTCC is not convenient due to the size of the required gas turbine and of the gasification island. The “partial” BIG/GTCC appear to be better alternative, by the combination of the torrefaction pretreatment and entrained flow gasifier, CHOREN Carbo-V® type, permitting a net electricity generation efficiency of 14.7% and the increment of the CEST cogeneration efficiency; , using wet sugarcane bagasse as feedstock. This arrangement avoid observed problems in previous experiences with the continuum handling and feeding of shredded sugarcane bagasse to the gasifier.

Energy-loss Analysis of Thermal Power Unit Based on Multifactor Disturbance Theory

A new energy-loss analysis based on multifactor disturbance theory was studied in this paper. Due to the strong coupling characteristic of steam turbine system, the disturbance factors were decoupled and categorized. The main steam pressure, main steam temperature, reheat steam temperature and exhaust steam pressure were categorized as the large independent disturbance factors, while the terminal temperature differences (TTDs) of the regenerative heaters were categorized as small independent disturbance factors. The single-factor calculation method for energy-loss of heater TTDs neglected the interaction between each heater, thus all heater should be considered as a whole system when calculating the energy-loss of TTDs changes. The energy-loss of large independent disturbance was calculated based on global variable condition calculation method. Through calculating the energy-loss caused by the classified disturbance factors, the relative errors between the theoretical value and operation value were -3.00% for100%THA (turbine heat acceptance), -9.75 for 75%THA and 16.47% for 50%THA. The relative errors meet the requirements of the onsite guidance.

Energy analysis on Coalbed Methane (CBM) coupled power systems

Coalbed Methane (CBM) contains 97% of CH4 and very less amount of sulphur. Methane is a very high calorific value (≅55.7MJ/kg) gas as well as a greenhouse gas, which gets adsorbed on coal beds during coalification. Hence, capture of this CBM gas prior to coal mining not only prevents fire hazard but also the emission of greenhouse gas into the atmosphere. As the CBM gas is enriched in chemical energy, it is a promising source for power generation. In the present study, Raniganj (Jharkhand, India) Coal Field (RCF) properties are considered for CBM case study. A detailed energy analysis for the CBM and ECBM integrated carbon neutral power generating systems such as steam turbine, combined cycle (CC) and fuel cell systems is presented and the net thermal efficiency of each power plant with carbon capture and storage is estimated. High pressure coal seam is considered for combined cycle and solid oxide fuel cell (SOFC) cycle operation. Integration of power plant with CBM is studied for various coal seam operating pressures in the range of 3–1MPa and a high net thermal efficiency of 68.3% is found at 30bar with carbon capture and storage (CCS) for CBM integrated fuel cell cycle. In case of CBM integrated combined cycle and steam turbine system, a net thermal efficiency of 45% and 41% is estimated, respectively. An increase in 0.5% net thermal efficiency is calculated for ECBM case as compared to CBM under identical operating conditions of coal seam.

MANAGING ENGINEERING INNOVATIONS IN THE PALM OIL INDUSTRY

The engineering innovation outlook in Malaysia is not very good. The estimated number of technical people in Malaysia was reported to be only around 0.7 per cent of the workforce as compared to 30 per cent in the advanced countries. The government has set up various agencies and has launched various policy guidelines to create the ecosystem that can stimulate and sustain innovation and creativity in the palm oil industry. More incentives and support from all related agencies are needed to encourage capital investment in innovation. Entrepreneurs planning to seed technology innovation into the palm oil industry must provide in-depth technical guidance and engineering support services to the millers to ensure efficient plant operation and maintenance. Without adequate technical support services, the technology cannot develop its roots in the industry and the potential innovation is pre-maturely dismissed as an unsuitable technology for the palm oil industry. Potential disruptive technologies, such as the Evaporator Technology and the ORC (Organic Rankine Cycle) Biomass Power Plant Technology, need to be recognised and managed differently. The entry of the disruptive innovation, such as the Evaporator (zero liquid discharge) Technology, into the palm oil industry may initially be confined to a limited market segment, such as near to population areas, before becoming the standard practice in the industry eventually. The ORC biomass power plant may enter into the palm oil industry at the start as a BOOT (build, own, operate and transfer) project. The sound financial viability of the BOOT project will quickly convince the palm oil millers to invest in the new innovation themselves to replace their existing inefficient boiler and steam turbine systems. The established related businesses, that are going to be affected by the potential disruptive technologies, must not ignore the entry of these disruptive innovations. They must adopt appropriate management practices that enable them to fit in with the ongoing disruption in the marketplace in order for them to survive. Mill owners, who are alert enough to recognise the emergence and presence of disruptive innovations, would take the appropriate preventive measures to safeguard their interests. Keywords: Technologies, palm oil industry, sustaining innovation, disruptive innovation.

Experimental performance of an advanced metal volumetric air receiver for Solar Towers

Solar Tower Technology is a promising way to generate sustainable electricity from concentrated solar radiation. In one of the most effective variants of this technology, a so called volumetric air receiver is used to convert concentrated radiation into heat. This component consists of a high temperature resistant cellular material which absorbs radiation and transfers the heat to an air flow which is fed from the ambient and from recirculated air. It is called volumetric, because the radiation may penetrate into the “volume” of the receiver through the open, permeable cells of the material. In this way a larger amount of heat transfer surface supports the solid to gaseous heat transfer in comparison to a tubular closed receiver. Finally the heated air is directed to the steam generator of a conventional steam turbine system. In this study an advanced cellular metal honeycomb structure has been designed, manufactured and tested for use as an open volumetric receiver. It consists of winded pairs of flat and corrugated metal foils. The technology is based on a one which has been primarily developed for the treatment of combustion engine exhaust gases. A number of variations of the pure linear honeycomb structure have been introduced to increase local turbulence and radial flow. Firstly, a set of samples has been tested in laboratory scale experiments to determine effective properties and the solar-to-thermal efficiency. After that, results have been compared with theoretical predictions. Finally, the three most promising materials have been used for a 500 kW test on the research platform of the Solar Tower Jülich. Air outlet temperatures of more than 800 °C have been achieved with efficiencies of about 80%, which is about 5% more than the state-of-the-art technology, which is currently used at the main receiver of the Solar Tower. Next to this, lifetime models will be developed to increase the overall reliability of the technology.

二相ノズルおよびタービンに関する研究

Low temperature thermal energy included in hot spring or waste-heat at factories has been abandoned until now. It is reported that geothermal heat of up to 120 degrees corresponds to the energy of 7.4GW. Among them, a new technology that attempts to recover the thermal energy by driving turbine with two-phase flow which is generated by flashing hot water has been developed. The high momentum and low velocity two-phase flow drives the turbine at synchronous speed to the generator. This eliminates the need for the expensive gearbox required for the conventional steam turbine systems and thereby improves the reliability and reduces the maintenance. However, the improvement of efficiency and stability is required to put to the practical use. Therefore, the basic experiment to understand the performance of two-phase turbine and flashing nozzle was conducted and discussed by using water instead of organic fluid. Water is expected to be used to prevent the environmental destruction. The visualization of two-phase flow at the nozzle exit was conducted and the power output of two-phase turbine was measured. The experimental and analytical results showed that: (1) the non-equilibrium degree changed from nozzle throat to exit.; (2) steel wool in the convergent part of nozzle could effectively reduce the non-equilibrium and suppressed the pulsation of two-phase jet; (3) the practical two-phase jet velocity was obtained from the maximum turbine efficiency and compared with the prediction with non-equilibrium model.

Program development for performance analysis of a steam turbine system with the use of overload valve

The global energy market has grown steadily as various energy technologies have been developed. Renewable energy has been used widely but conventional power plants are still used as major electric power sources, including steam turbines and gas turbines. Recently, flexible power plant operation in terms of load management has become important in the power generation industry. For flexible operation, overload valve operation has been introduced for ultra-supercritical steam turbine plants. Overload valve operation is an operation wherein some of the steam at the control valve is bypassed into the middle of the high pressure turbine. In this study, an in-house program is developed for the analysis of ultra-supercritical steam turbines using overload valve operation. A full off-design analysis is performed based on theoretical and empirical correlations. Four kinds of operations were comparatively investigated; control valve operation, sliding pressure operation, and two types of overload valve operation. The influence of the overload valve is analyzed in terms of operating characteristics and performance.