Power Units In China Research Articles

Which coal-fired power units in China should be prioritized for decommissioning?

China's total installed coal power capacity is larger than that of all other countries combined. However, for China to attain its objectives of carbon peak in 2030 and carbon neutrality in 2060, a considerable number of these units will have to be phased out. Therefore, it is crucial to identify which coal-fired power units should be prioritized for decommissioning. This study constructs a stacking evaluation model comprising multiple sub-models, based on the power resource endowment, power generation efficiency, and social responsibility. This model is employed to assess each existing coal-fired power unit in China, with the objective of determining which units should be prioritized for retirement. Additionally, the impact on power supply and heating systems in various Chinese provinces is assessed based on these decommissioning scenarios. The results show that: ① Compared to a single model, the stacking evaluation model developed in this study exhibits higher accuracy and robustness. ② China should prioritize the phasing out of small, inefficient coal-fired power units that do not supply heat and are located in regions with a higher proportion of thermal power generation. Approximately 23.1 % (679 units) of coal-fired power units will need to be retired by 2030. ③ The retirement of outdated coal-fired power units will lead to a more efficient, modern, and healthier Chinese power system. ④ The closure of 679 outdated coal-fired units will not result in a shortage of electricity but will substantially affect urban heating. Northern provinces reliant on district heating anticipate a loss of 516.42 million GJ/year in heating capacity.

Multifactor configurations of coal power technology in China substantially differ in life-cycle environmental impacts

The expansion of coal power in China has led to a coexistence of multiple technologies, whereas differences in environmental impacts of each other remain hitherto unclear. This gap is largely a result of the difficulty of fully covering the factors that significantly affect environmental performances and the lack of fine data inventory. The limitation welcomes an approach that can go well beyond characterizing coal power technology with a single factor. To this end, we surveyed the information data for all coal power units in China to couple four factors (viz. operating parameter, boiler type, cooling approach, and turbine mode) into 22 types of multifactor technology configurations, as well as the first-hand operating data of nearly half of all coal power units in China to compile an elaborate data inventory that each configuration includes 88 input and output data. These fine data were modeled by the life cycle assessment method of CML 2016 to quantify twelve environmental impact categories. The results show substantial differences in environmental impacts exist for different technology configurations. High operating parameters gain environmental friendliness but the diversification of boiler type and cooling approach to improve the applicability of coal quality and water resources increases environmental impacts. The insignificant impact of the turbine mode is owning to the exergy allocation that eliminates the quality gap in electrical and thermal energy. The technology-level differences are aggregated into the provincial level by various configuration structures, which show markedly spatial heterogeneity varying by impact categories. This implies a great potential for structural adjustment and an overall improvement requires cleaner production beyond that, focused on the coal power generation process and its upstream coal supply process. Our modeling shows a majority of results with an uncertainty of lower than 10 %, which is robust for the proposal of policy suggestions.

Quantifying stranded assets of the coal-fired power in China under the Paris Agreement target

ABSTRACT Coal-fired power plays a critical role in China’s compliance with the Paris Agreement. This research quantifies China’s stranded coal assets under different coal capacity expansion scenarios with an integrated approach and high-precision coal-fired power database. From a top-down perspective, firstly, the pathway of China’s coal-fired power capacity consistent with the global 2°C scenario is outlined and then those stranded coal-fired power plants are identified with a bottom-up perspective. Stranded value is estimated based upon a cash flow algorithm. Results show that if coal capacity stabilizes during 2020–2030, China will only incur a sizeable yet manageable stranded asset loss (USD 55 billion, 2020–2045). However, a continued increase of coal-fired capacity, of another 200∼400 GW, would significantly enlarge the loss by 2.7∼7.2 times. Further, once commissioned coal-fired power would form a resource lock-in effect. Thus, it will miss a short-term opportunity to develop new energy sources and induce a long-term need to invest in coal-fired power negative emission technology. Therefore, halting the construction of new coal-fired plants is a low-cost and no-regret option for China. Key policy insights Even with the largest coal-fired power capacity in the world, China still has the chance to decommission the coal-fired power units gradually at a relatively low cost. Continuing to build new coal-fired power units in China will increase the risk of stranded assets, especially for North China Grid and Northwest China Grid. Taking immediate action to stop building new coal-fired power units would be the low-cost and no-regret option for China. The local financial sector needs to work with the energy sector to gradually withdraw from the coal sector and support clean and renewable energy.

Dispatch optimization of thermal power unit flexibility transformation under the deep peak shaving demand based on invasive weed optimization

The rapid development of new energy represented by wind power and photovoltaic power generation necessitates higher requirements for the flexibility of traditional thermal power generation units. The role of thermal power units will change from conventional main power to auxiliary power, not only because of the need for the survival and development of thermal power enterprises, but also because of the inevitable requirement for promoting the revolution of power energy production and consumption in China. The economy of thermal power unit flexibility transformation is an important constraint factor for decision-making in thermal power unit transformation. How to consider the economic factor of the thermal power unit transformation is a key problem for decision-making. In this paper, a nonlinear programming model is proposed to solve the problem. By introducing greedy strategy and improved reproduction strategy, an improved invasive weed optimization (IWO) algorithm is also proposed to solve the problem. Finally, a case study with three different scenario assumptions was conducted according to the most used transformation schemes of thermal power units in China, and the results were derived by using the proposed model and the improved IWO method. The comparative analysis of the results showed that the more the thermal power units participated in deep peak shaving, the greater the risk of the flexibility transformation of the thermal power units. In addition, under the condition of the same proportion of peak shaving, the risk of transformation without oil peak shaving was lower than that of oil peak shaving. Thus, the improved IWO algorithm can provide a stable and satisfactory solution. The research in this paper can provide a more scientific basis for decision-making on the flexibility transformation of the thermal power unit and can provide a reference for the selection of the flexibility transformation scheme of the thermal power unit.

Discharge characteristic of barbed electrodes in electrostatic precipitator

Electrostatic precipitator (ESP) is the mainstream technology for controlling emissions of coal-fired thermal power units in China. The barbed electrode (RS or BS) is paired with the electrostatic precipitators. However, such electrodes have serious internal suppression effects and easily cause the current density in some areas to be zero, affecting the electric field distribution. To explore this characteristic, the current density distribution on the surface of the collecting plate was tested on the electrostatic precipitator experimental device, and the suppression effect of the BS barbed electrode and the existence of the “current blind zone” were obtained. The mathematical model of corona discharge was then established to numerically solve the V-I characteristics of the BS barbed electrode's inner and outer discharge tips and quantify the suppression effect between the discharge tips. Finally, to improve the suppression effect and the current density distribution, the BS barbed electrode's structural parameters optimization schemes and supporting circular tubes in the single electrode-plate ESP model were proposed. The results show that the spurs' optimized structure can effectively improve the corona discharge capacity and weaken the suppression effect. At the same time, it was found that when the supporting component is a round tube or flat plate, the shielding effect will be produced. The addition of auxiliary needles on the supporting round tube cannot improve the current density distribution. Additional needles on the supporting plate can eliminate the phenomenon that the current density is zero. The shielding effect of the supporting tube is further explained. The research results provide a theoretical and experimental basis for the optimal design of barbed electrode and ESP's electrode configuration.

A data-based approach for benchmark interval determination with varying operating conditions in the coal-fired power unit

The modern coal-fired power units in China are mostly operated in a flexible manner. However, flexible operation results in performance degradation, energy-efficiency penalties, and increased energy consumption, which necessitates the detection of performance degradation to save energy. This paper presents a model for detecting the performance degradation of coal-fired power units by determining the benchmark intervals of variables under varying operating conditions using data-mining methods. The K-means clustering method is employed to categorize the operating conditions according to the similarity of historical operational data. Gaussian mixture model is adopted to determine the benchmark interval with respect to the varying operating conditions by estimating the probability of historical runtime data. The methodology is validated using a feedwater heating system of an on-duty coal-fired power unit. The results indicate that in comparison with the design-based method, the proposed method can provide benchmark intervals for 225 operating conditions. In addition, the determined benchmark interval can detect performance degradation earlier than design-based values, thereby providing opportunities for energy-efficiency enhancement.

What are the resource benefits of circulating fluidized bed power generation technology? Take some key thermal power units in China as an example

Efficient use of natural resources is an important part of China's energy industry to achieve sustainable development. The promotion of circulating fluidized bed (CFB) boilers is an important way to save coal and other resources from the source. This article first analyzes the connotation of resource benefits generated by CFB boilers. From the perspective of CFB technology used for low-calorific value coal recycling, coal recovery rate and sustainable development of coal resources (mainly coal can extend mining time), the resource benefits obtained by CFB are analyzed. The resource benefits obtained were analyzed. Second, based on the input-output nonlinear optimization theory, aiming at maximizing the resource benefits of CFB technology, constructing a CFB technology resource benefit nonlinear optimization model, measuring output benefits-added value, that is, the extension time of coal years and coal mining recovery rate increased value. Finally, based on the installed capacity data of China's CFB technology units from 1990 to 2015, the model designed two scenarios for China's future CFB technology development, and predicted China's 2020 CFB machine assembly capacity and power generation. On this basis, by analyzing the degree of coal resource conservation and the extension of the exploitable years, the model derives the resource benefits generated by CFB technology under different scenarios and the impact on the sustainable development of China's coal resources. These conclusions provide a quantitative basis for China's future CFB technology development.

Research on Optimization of Emission Reduction Scheme for Thermal Power Based on Linear Programming

Coal-fired thermal power units emit a large amount of air pollutants, which has aggravated air pollution in China and seriously affected people’s life and health. Therefore, it is necessary to formulate more reasonable emission reduction plans for thermal power units in China, so as to reduce air pollution. In order to maximize the comprehensive benefit of thermal power emission reduction, this paper put forward a method of optimizing the emission reduction scheme of thermal power units based on linear programming, and calculated the emission reductions in future.

Application Prospect of Coal-fired coupled Biomass in Technical Transformation of Thermal Power Unit

The development of thermal power units in China is restricted. In the process of transformation, coupled biomass power generation is the main direction of the transformation in the fuel sides. This paper introduces the constraints of thermal power units, the main ways of coal-fired coupling power generation, the technical route of coupling biomass in all of 84 pilot thermal power units and the problems faced by coupled biomass power generation. On this basis, some suggestions on the application of coal-fired coupling power generation in enterprises are put forward.

Allocating Output Electricity in a Solar-Aided Coal-Fired Power Generation System and Assessing Its CO2 Emission Reductions in China

Coal-fired power generation in China is facing huge challenges due to its high share in the total electricity generation and its environmental problems. A solar-aided coal-fired power generation (SACPG) system, based on the integration of solar thermal energy into a conventional coal-fired power system, is an effective way to utilize solar energy and reduce coal consumption. The reasonable allocation of output electricity to solar energy and coal in a SACPG system and the evaluation of its CO2 emission reductions can help to acquire subsidies or financial support granted to renewable electricity and CO2 emission reductions. A methodology is proposed from the view of the technical characteristics of a SACPG system and the government regulation. The coal-to-electricity efficiency of the baseline unit or the coal-fired power system in a SACPG system is the key factor in the methodology, and it can be calculated on the basis of the norm of energy consumption of coal-fired power units in China. Then, the allocation of the output electricity to solar energy and coal can be calculated, and so can the CO2 emission reductions by the solar-coal hybrid system. Taking a 600 MW SACPG system as an example, the methodology is further illustrated. The methodology can guarantee that the calculation of output electricity allocation in a SACPG system and the calculation of its CO2 emission reductions are accurate, conservative and transparent for its subsidies or financial support.

Pollutant Emission and Energy Consumption Analysis of Environmental Protection Facilities in Ultra-Low Emission Coal-Fired Power Units

A total of 30 coal-fired power units in China were assessed with regard to the effects of ultra-low emission retrofitting on pollutant emission and on the consumption of both energy and materials of environmental protection facilities. SO2, NOx, and dust emission were compared, together with the energy and material usage of desulfurization and selective catalytic reduction denitrification facilities before and after retrofitting. Following retrofitting, the average SO2, NOx, and dust emission performance were 0.042, 0.1, and 0.004 g/(kW·h), respectively, all of which are much lower than the current averages of coal-fired units in the United States. The average station service power consumption rate of desulfurization facilities increased from 1.12 to 1.29% following retrofitting, while limestone usage increased from 112.6 to 155.5 kg/(104 kW·h) and liquid ammonia consumption increased from 4.1 to 4.31 kg/(104 kW·h).

Analysis on operation reliability of wind power units in China

As an important direction of renewable energy, wind energy has developed rapidly, but there are also many problems. The reliability of wind turbines has received wide attention. This paper mainly studies and analyzes the development of wind turbines, basic structure, operation and maintenance of the unit, and then puts forward suggestions for improving the reliability of wind turbines in China.

Development Status and Outlook for Nuclear Power in China

This paper introduces the basic situation and the latest progress of nuclear power units in China, as well as the related measures of improving the safety level of nuclear facilities. Under the requirement of the “national energy administration's 13th five-year plan for energy technology innovation”, China has launched a series of development plans for nuclear power and small modular reactors, carryed out the demonstration construction project of marine nuclear power platform, and established relevant standards. At last, it summarizes the current challenges and future outlook for nuclear power in China.

Tempospacial energy-saving effect-based diagnosis in large coal-fired power units: Energy-saving benchmark state

The energy-saving analytics of coal-fired power units in China is confronting new challenges especially with even more complicated system structure, higher working medium parameters, time-dependent varying operation conditions and boundaries such as load rate, coal quality, ambient temperature and humidity. Compared with the traditional optimization of specific operating parameters, the idea of the energy-consumption benchmark state was proposed. The equivalent specific fuel consumption (ESFC) analytics was introduced to determine the energy-consumption benchmark state, with the minimum ESFC under varying operation boundaries. Models for the energy-consumption benchmark state were established, and the endogenous additional specific consumption (ASFC) and exogenous ASFC were calculated. By comparing the benchmark state with the actual state, the energy-saving tempospacial effect can be quantified. As a case study, the energy consumption model of a 1000 MW ultra supercritical power unit was built. The results show that system energy consumption can be mainly reduced by improving the performance of turbine subsystem. This nearly doubles the resultant by improving the boiler system. The energy saving effect of each component increases with the decrease of load and has a greater influence under a lower load rate. The heat and mass transfer process takes priority in energy saving diagnosis of related components and processes. This makes great reference for the design and operation optimization of coal-fired power units.

Does China’s Energy Development Plan Affect Energy Conservation? Empirical Evidence from Coal-Fired Power Generation

ABSTRACTDrawing on provincial panel data in China, we study the causal relationship between generation hours and coal consumption rate of coal-fired power and its implication for energy conservation in China’s energy development plan. Empirical results suggest that (1) low generation hours resulting from peak regulation were the main reason for poor efficiency of coal-fired power units in China; (2) increase in power generation hours reduces the coal consumption rate of coal-fired units, but about 70 percent of this effect depends on the dispatching modes; (3) according to China’s Twelfth Five-Year Energy Plan, generation hours of coal-fired power will decrease by 2015 compared to that of 2006–10, which would have adverse effects on coal consumption of rate of coal-fired power plants.

A data envelopment analysis for energy efficiency of coal-fired power units in China

In this article, the non-parametric data envelopment analysis method (DEA) is employed to evaluate energy efficiency (EE) of 34 coal-fired power units in China. Input-oriented CCR (Charnes, Cooper and Rhodes) model is used for EE analysis. Two efficiency indices, generalized EE and special EE are defined and analyzed. The generalized EE is calculated based on four input parameters: coal consumption, oil consumption, water consumption and auxiliary power consumption by power units. The special EE is only based on two input parameters: coal consumption and auxiliary power consumption. Relations between these two EE indices and non-comparable factors including quality of coal, load factor, capacity factor, parameters of main steam and cooling method are studied. Comparison between EE evaluation results of the two indices is conducted. Results show that these two kinds of EE are more sensitive to the load factor than the capacity factor. The influence of the cooling method on EE is larger than that of main steam parameter. The influence of non-comparable factors on the special EE is stronger than that on the generalized EE.

ICOPE-15-C080 Comparative Study on Foundation Dynamic Characteristics of Nuclear Power Units in China

ICOPE-15-C080 Comparative Study on Foundation Dynamic Characteristics of Nuclear Power Units in China

Heat transfer characteristics and energy-consumption benchmark state with varying operation boundaries for coal-fired power units: An exergy analytics approach

The energy-saving analytics of coal-fired power units in China is confronting new challenges especially under varying working conditions and operation boundaries, such as load rate, coal quality and ambient temperature. Compared with traditional optimization of specific operating parameters, the idea of energy-consumption benchmark state was proposed. The exergy analytics was introduced to determine the energy-consumption benchmark state, with the minimum exergy destruction under varying operation boundaries. The heat transfer coefficient and condenser vacuum were calculated by considering the influence of operation boundaries in different coal quality and ambient temperature. The coal rate was figured out for the coal fuel in different composition and calorific values, for the circulating water condition in different temperatures and cooling modes with different load rate. As a case study, the energy consumption model of a 1000 MW ultra supercritical power unit was built on the platform of Ebsilon and tested by practical operation data of power unit. The results show that the heat transfer coefficient and condenser vacuum change greatly with different coal composition and circulating water temperatures under different working conditions. The energy-consumption benchmark state of power unit is also operation condition and boundary-dependant. The coal rate of such benchmark state is considerably less than that of the actual state with the same operation boundaries. This makes great reference for the operation optimization of coal-fired power units.

Analysis of Energy Efficiency for Coal-fired Power Units Based on Data Envelopment Analysis Model

In this article, the non-parametric data envelopment analysis method (DEA) is employed to evaluate energy efficiency (EE) of coal-fired power units in China. The data set contains inputs and outputs of 34 coal-fired power units with the capacity of 600MW. Input-oriented CCR (Charnes-Cooper-Rhodes) is employed. The value of CCR efficiency calculated in this paper is based on two input parameters: fuel consumption and auxiliary power consumption. The relations between EE and factors including, parameter of main steam, cooling method, capacity utilization rate and annual utilization hours are analysed. Some relation curves are fitted.

A nonlinear model of flow-structure interaction between steam leakage through labyrinth seal and the whirling rotor

A nonlinear model of flow-structure interaction between steam leakage through labyrinth seal and the whirling rotor was presented. The particular concern was placed on incorporating thermal properties of the steam fluid into the mathematical model. To see the influence of the steam fluid on the whirling rotor, two sets of thermal parameters of the steam fluid, e.g., temperature and pressure drop in each seal cavity, were selected from the typical 1000 MW supercritical and 300 MW subcritical power units in China. The interlocking seal widely employed in practical situations was chosen for study. The rotor-seal system was modeled as a Jeffcott rotor subject to shear stress and pressure force associated with the steam leakage. Spatio-temporal variation of the steam forcing on the rotor surface in the coverage of the seal clearance and the cavity volume was specifically delineated by using the Muzynska model and the perturbation analysis, respectively. The governing equation of rotor dynamics including the influence of the steam leakage was solved by using the fourth-order Runge-Kutta method, resulting in the orbit of the whirling rotor. Stability of the rotor was inspected by using Liapunov’s first method. The results showed that the destabilization speed of the rotor was significantly influenced by the steam leakage.