Peng Fu

Models for Entropy Analysis of Single-Phase Heated Surface under Transient Condition and Analysis on Its Contrast with That of Steady Condition

The aim is to describe the irreversibility of energy system under transient conditions scientifically and analyze the further dynamic reasons. Models for entropy distribution under transient conditions are established and applied to reheater of a 1913t/h-boiler. The results show that some error occurs when model for steady conditions are used for transient conditions. The main reason is that the heat stored in metal and the time rate of entropy are ignored.

Energy Consumption of Turbine Unit with Varying Exhaust Pressure under Off-Designed Conditions

The exhaust pressure affects the economic performance of the whole power unit greatly. Based on the theory of energy specific fuel consumption (ESFC), the changing principle of energy consumption in a power unit was studied. In the turbine unit, the energy-consumption caused by topological factors was also discussed with different exhaust pressure. The results showed that the changing of exhaust pressure makes great effects on topological energy consumption of steam turbine. It makes great reference for the energy-saving diagnosis of the energy consumption for the overall power units.

Thermal Economic Analysis of Desuperheating System in Large Scale Power Generation Unit

The desuperheating water can affect the thermal economy in a power plant. Based on the equations of mass and energy balance equations for steam-water distribution, the calculation model for the thermal economic performance of the thermal system in a coal-fired power plant was established. And this model was used in a 1000MW ultra supercritical coal-fired power generation unit under different conditions with varying flow of desuperheating water (DW). The results show that the DW of reheater has larger impact on the thermal economic of power unit than that of superheater.

Multi-Factors Analysis of Condenser Vacuum under Overall Working Conditions

It is of great significance to determine an optimal condenser vacuum for energy-saving diagnosis, for the vacuum means a lot to the safe and economic operation of thermal power units. The key parameters were calculated by the practical data, such as the cleanliness factor. The condenser heat transfer coefficient is affected by both the dirty of condenser water side and other factors on the basis of the method of adjusting the circulating-water flow unilaterally to get the optimal vacuum of condenser in this paper. The impacts of the exhausting steam resistance, the oxygen content of condensate caused by the change of the circulating-water flow were considered in this paper. The practical operation data was analysed with the results from HEI. The simulations were examined in the comparison of heat transfer coefficient. The impacts of unit energy consumption characteristics under overall working conditions caused by condenser vacuum were obtained in the approach based on the theory of energy specific fuel consumption (ESFC). The variation of auxiliary specific consumption as the temperature of circulating-water changing was obtained. The results indicated that the optimal condenser vacuum determined by the method aiming at maximum output power and many factors under overall working conditions accounted for played an important role in the energy saving diagnosis of thermal power units.

Method for Determining Energy-Consumption Benchmark State in the Thermal System of Coal-Fired Units Based on Hybrid Model

Considering the varying operation conditions and ambient constraints, the in-depth energy conservation of thermal power units is confronting new challenges. Based on the already made ‘energy-consumption benchmark state’ concept, the description of energy-consumption benchmark state was obtained in this paper to describe the economic performance of coal-fired power thermal system with the varying operation boundary, operation conditions and equipment performance. Breaking the limitations of traditional modelling which always make statistic analysis and mechanism analysis isolate, hybrid modeling method synthesizing the merit of the mechanism analysis and statistical method was proposed. Considering the heat transfer characteristics of thermal system, this model make the energy-consumption of unit correspondence with parameter sets of thermal system. Optimized parameter sets were gained with the fuel specific consumption setting as the optimization objective, thus obtain the energy-consumption benchmark state in thermal system of coal-fired units. The results show that the method for determining energy-consumption benchmark state in the thermal system of coal-fired units based on hybrid model makes significant reference for the energy-saving diagnosis and operation optimization of thermal power units under overall working conditions.

Mechanism of Energy-Consumption Benchmark State for Coal-Fired Power Units with Varying Boundary

The in-depth energy conservation of thermal power units is confronting new challenges under the varying operation conditions and ambient constraints. Compared with traditional optimal values, the description of energy-consumption benchmark state was proposed to describe the economic performance of thermal power units with the varying operation boundary, operation conditions and equipment performance. The energy consumption interactions of units were divided into 4 parts: parameters, equipment, subsystems and units. The models for energy-consumption benchmark states were established with the fuel specific consumption (FSC) setting as the optimization objective. Such a method was performed on a 600MW supercritical power unit and the results show that the energy-consumption benchmark state, which is related with the varying boundary, can reflect the boundary condition, operation lever and equipment performance. It makes significant reference for the energy-saving diagnosis and operation optimization of thermal power units under overall working conditions.

Distribution Characteristics of Exergy Dissipation of a Large-Scale Coal-Fired Power Generation Units

The distributions of exergy dissipation in a 1000MW coal-fired power plant under different operation conditions were analyzed. Mass and energy balance models of different components were constructed to determine the thermodynamic properties of each stream. A variant of exergy analysis, the proposed equivalent specific fuel consumption (ESFC) analysis, were conducted to determine the additional specific fuel consumptions (ASFC) of individual component and, therefore, to obtain the characteristic of its temporal and spatial distribution. The off-design modeling of main components was established. The methodology and results of analysis in this paper can be taken as valuable guidance for the optimal design and operation of thermal power plants and for the improvement and retrofits for more cost-effective and environmental-friendly power plants.

Thermodynamic Models and its Application for Open Feedwater Heaters under Transient Conditions

The aim of this paper is to find the energy distribution principle of open feedwater heaters under transient conditions. Taking a heater as the example and employing the first and second law of thermodynamics, thermodynamic models for vapor-liquid, mixture-liquid and liquid-liquid heaters were established and applied. And its energy distribution is obtained. The results indicate that that some error occurs when models for steady conditions are used at transient states. And the drain-cooler section has the largest error. The major factor is the exergy stored in exothermic fluid.

Simulation and Investigation on Exergy Destruction Distribution in Single-Phase Heated Surfaces of Boiler under Transient Conditions

The aim is to describe the irreversibility of energy system under transient conditions more scientifically and to lay foundation for further energy saving under transient conditions. On the basis of the existing research, a model for exergy destruction in single-phase heated surfaces of boiler under transient conditions was established. Taking a 1913t/h-boiler as an example, exergy destructions in single-phase heated surfaces of the boiler and their distributions among processes were calculated respectively. The results were compared with those calculated by models under steady conditions. The analysis shows that exergy destruction in each heated surface under transient condition is still mainly related to the difference of temperature and transferred heat. Some error occurs when models for steady conditions are used for simulation of transient conditions. The main reason is that the heat stored in metal as well as the time rate of exergy is ignored.