Latest ArticlesDriven by the “dual-carbon” goals, the establishment of integrated energy systems in industrial parks, and the large-scale renewable integration have imposed heightened flexibility requirements on coal blending for thermal power units. The coal blending process comprises two stages: pre-furnace and in-furnace operations. During pre-furnace blending, a minimum coal quality deviation model addresses low-calorific-value coal utilization. Chaos search-based adaptive mutation particle swarm optimization blends such coal into furnace-compliant mixtures meeting boiler specifications. For in-furnace blending, dynamic adjustment of coal ratios across load ranges ensures load stability while minimizing fuel costs. A two-stage optimization model resolves circulating fluidized bed (CFB) boiler blending: Stage 1 selects coal feeder combinations according to weekly peak chemical plant loads and PV generation scenarios; Stage 2 optimizes coal feed rates under load-balance constraints, incorporating desulfurization-driven sulfur content limits. Comparative analysis under spring irradiance conditions reveals that in-furnace blending of two coals reduces daily combustion costs by 4.36×105 yuan. Post-retrofit evaluation of blending of three coals demonstrates a further reduction in daily fuel costs.
This study aims to investigate the applicable conditions and key operational parameters for an integrated compression, purification, decarbonization, and denitrification process applied to natural gas oxy-fuel combustion flue gas. The research seeks to clarify the technical feasibility and performance boundaries of this process for achieving efficient carbon dioxide (CO2) capture coupled with deep removal of nitrogen oxides (NOx), providing a practical solution for integrated carbon capture and pollutant control in natural gas oxy-fuel combustion systems.
A steady-state process model for the compression and purification of oxy-fuel combustion flue gas was developed using Aspen Plus, which accurately describes the thermodynamic behavior of the high-pressure, multi-component gas mixture. Through systematic simulation and parametric sensitivity analysis, the study focused on the combined effects of the initial CO2 volume fraction in the flue gas and the system operating pressure on process performance. Key performance indicators evaluated include the CO2 recovery rate, liquid CO2 product purity, NOx removal efficiency, and specific comprehensive power consumption.
The simulation results establish a definitive and strong correlation between the CO2 recovery efficiency and the initial concentration of CO2 in the flue gas. A clear technical threshold is identified: to attain a CO2 recovery rate of 80% or higher, the initial CO2 volume fraction must exceed 60%. This finding defines a primary applicability criterion for the compression-purification approach. Subsequent analysis concentrated on flue gas compositions meeting this high-concentration criterion (>60% CO2). Within this domain, the system operating pressure emerges as the most influential parameter governing the synergistic relationship between NOx abatement and CO2 purification efficiency. Detailed parametric optimization reveals a distinct optimal operating pressure of 2.8 MPa. Operating at this pressure enables the process to achieve superior performance across all key metrics: the NOx removal efficiency surpasses 94%, the purified liquid CO2 product attains a purity of 95% or higher, and the target CO2 recovery rate of ≥80% is reliably maintained. Crucially, this operating point corresponds precisely to the minimum in specific power consumption, which is quantified at 120.1 kW·h per ton of CO2 captured. This represents an optimal trade-off, balancing high environmental performance with minimized energy penalty, a critical factor for economic feasibility.
The compression and purification technology is suitable for treating oxy-fuel combustion flue gas with a high initial CO2 volume fraction (>60%). By optimizing the system pressure to 2.8 MPa, efficient CO2 capture and deep NOx removal can be achieved simultaneously with low energy consumption. This study clarifies the key performance thresholds and optimal operating parameters for this integrated process, providing a concrete and feasible technical solution for achieving pollution reduction, carbon mitigation, and resource utilization in natural gas oxy-fuel combustion systems.
Driven by the large-scale integration of renewable energy and the national “dual-carbon” strategic goals, the construction of a new power system imposes higher requirements on the flexible operation of coal-fired units. However, coal-fired units face challenges such as reduced combustion instability and steam parameters deviating from design values during low-load operation. Therefore, in-depth research on coordinated control characteristics of low-load stable combustion and flue gas temperature in boilers is of significant importance for deep and flexible peak regulation. Taking a 600 MW subcritical tangentially fired boiler in a power plant as the object, the effects of injecting primary air exhaust gas from the pulverized coal conveying system into different locations of the furnace (main combustion zone, reduction zone, burnout zone) on the velocity, temperature and component concentration field, and the flue gas temperature at the platen zone are systematically studied under 50% load condition. The analysis specifically focuses on the synergistic influence mechanism of combustion organization on the combustion stability of the boiler and the regulation of flue gas temperature. The results indicate that injecting primary air exhaust gas into various furnace locations can form a stable tangential flow pattern and high-temperature zone, without significantly affecting the boiler’s low-load combustion stability. Injecting the primary air exhaust gas into the reduction zone elevates the high-temperature flame region to some extent, which is beneficial for maintaining steam parameters during deep flexible peak regulation, yielding superior coordinated performance for both low-load stable combustion and flue gas temperature regulation. Through numerical analysis, the coordinated control strategy for achieving stable combustion at low loads and regulating flue gas temperature through the reuse of primary air exhaust gas is determined. The study results can provide a basis for the low-load operation of this type of coal-fired boiler during deep peak shaving.
To address the challenges of flow regulation and pressure mismatch in conventional solid-gas coupled hydrogen storage reactors, this study proposes a novel reactor configuration incorporating the Venturi entrainment effect. A multi-physics coupled numerical model is developed to investigate the influence of nozzle structural parameters and key operating conditions on hydrogen release performance, and comparative analyses are conducted against single-mode hydrogen storage systems. The results demonstrate that nozzle geometry has a significant nonlinear effect on entrainment performance. Specifically, a nozzle with a length of 9~13 mm and diameter of approximately 0.4 mm achieves an optimal balance between system stability and entrainment efficiency. Increasing the high-pressure hydrogen inlet pressure enhances the instantaneous flow rate but reduces the entrainment ratio. Higher outlet backpressure improves the entrainment ratio but suppresses the jet strength and dynamic response. Elevating the thermal management temperature of the solid-state hydrogen storage unit accelerates the initial hydrogen release rate, but its influence on the later stages is limited. With a solid-to-gas ratio of 1:1, the coupled hydrogen storage scheme reduces the volume by approximately 34.4% and the compression energy consumption by about 41.7% compared to a 20 MPa gaseous hydrogen storage scheme. Compared to the single-mode solid-state storage scheme, thermal management energy consumption of this coupled scheme reduces by nearly 50.0%, demonstrating a significant advantage in energy efficiency synergy. This study provides a theoretical foundation and engineering guidance for the structural optimization and operational strategy development of solid-gas coupled hydrogen storage reactors.
As an important path for the combination of renewable energy and hydrogen energy, the technology coupling wind solar power with hydrogen production and storage through water electrolysis has shown great potential in energy transformation. However, large-scale grid-connected hydrogen production stations have problems such as uneven power distribution and insufficient consideration of the differences in response characteristics between alkaline and proton exchange membrane (PEM) electrolyzers. Therefore, this paper proposes an optimized scheduling strategy for the double-layer array of wind-solar hydrogen production hybrid electrolyzers. Firstly, with the goal of maximizing the net income of the system, a multi-time-scale optimization strategy is adopted to allocate the power of the wind and solar hydrogen production system. Secondly, considering the differences in hydrogen production efficiency and dynamic response characteristics between the alkaline and the PEM electrolyzers, optimal scheduling is performed for the array of alkaline and PEM hybrid electrolyzers. As a result, based on the two-layer optimization strategy, the ratio of the on-grid electricity generation to the power generation of the grid-connected wind and solar hydrogen production and storage system is infinitely close to the set value of 40%, and the comprehensive power curtailment rate is 1.89%, which greatly reduces the curtailment rate of wind and solar power in the system. The operational characteristics of the alkaline and PEM electrolyzers are fully utilized to achieve the full utilization of fluctuating renewable energy and enhance the stability and safety of the hydrogen production system operation.
Ammonia-coal co-firing mode for power generation can significantly reduce the carbon emission level of the unit. But when the ammonia blending ratio is too high, the ammonia blending/pure ammonia burner is not properly arranged, and the ammonia-coal co-combustion effect is not good, the escaped ammonia will react with SO2/SO3 at low temperature, increasing the risk of corrosion and fouling on low temperature heating surfaces. To solve this problem, 168-hours continuous corrosion experiments of No.20 and ND steel specimens in an oxidizing atmosphere of NH3-SO2-O2-CO2-H2O(g)-N2 at 250 ℃ and 150 ℃ were carried out. The effects of temperature, NH3 volume fraction and fly ash coating on the corrosion rate of metal specimens were mainly investigated, and the corroded metal specimens and ash samples were analyzed in terms of micro-morphology and mineral phase. The experimental results showed that the average corrosion rate of ND steel specimens decreased by 58% when the volume fraction of ammonia was increased from 0.002 5% to 0.005 0%. The corrosion rate of No.20 steel coated with fly ash was significantly accelerated in the atmosphere of NH3 with volume fraction of 0.005%, and the average corrosion rate reached 0.003 6 mg/(cm2·h). Elevating temperature significantly accelerated the corrosion rate. ND steel coated with fly ash showed the fastest average corrosion rate at 250 ℃ (0.011 2 mg/(cm2·h)). At 250 ℃, CaSO3 was newly generated and it was detected in the ND steel-coated ash samples, which may have promoted adhesion among ash particles. After the corrosion of No.20 steel coated with fly ash at 150 ℃, the ash sample had a serious agglomeration effect, which is mainly due to the newly generated NH4HSO4 and (NH4)2SO3 promoting the agglomeration effect among ash particles. In the future, when a large proportion of ammonia is mixed with coal-fired units, especially when medium and high sulfur coal is used, special attention should be paid to the change of fly ash characteristics and the risk of fouling and corrosion on low temperature heating surfaces.
To address the reduction in power generation efficiency caused by dust accumulation on PV modules, this study proposes a seasonally optimal cleaning strategy that overcomes the limitations of conventional fixed-interval and dynamic cleaning methods which often neglect seasonal variability.
Based on historical meteorological and PV generation data, time-varying predictive models of the performance ratio (PR) and dust accumulation are established for spring, autumn, and winter. An improved multi-objective particle swarm optimization (IMOPSO) algorithm is developed, incorporating a differential evolution mutation strategy and a fitness value caching mechanism to enhance optimization performance. Taking both power output and cleaning cost as objective functions, the seasonal cleaning intervals are optimized.
Using a PV power station in Changzhou, Jiangsu Province as a case study, the optimized cleaning intervals are determined to be 25 days in spring, 28 days in autumn, and 20 days in winter. Compared to the uncleaned condition, the optimized strategy leads to increases in power generation of 1.83%, 2.01%, and 3.52% for spring, autumn, and winter, respectively.
The IMOPSO algorithm boasts fast convergence speed and uniform solution set distribution. The proposed seasonal cleaning strategy fully accounts for the impact of seasons on dust accumulation, enabling it to increase power generation while controlling cleaning costs. This provides a scientific basis for the formulation of cleaning schemes for photovoltaic power stations.
To solve the two core problems of solar-coal hybrid power generation, namely the high cost of solar collectors and the low solar conversion efficiency, a novel low-cost and efficient solar-coal hybrid power generation system was proposed.
In this new system, by using low-temperature evacuated tube solar energy to drive the waste heat recovery, the cost of solar collectors can be reduced significantly and solar amplified utilization is achieved. The performance of the new system was revealed by simulation, thermodynamic analysis, and economic analysis.
Based on a typical 600 MW unit, the new system exhibited a solar-to-electricity efficiency of 32.68% via the novel mode of evacuated tube solar-driven waste heat recovery. The cost of solar collecting devices in the proposed system was reduced to 34.9% of that in the conventional system. The cost of solar-generated electricity was kept at 0.440 yuan/(kW·h). [Conclusions] The thermal and economic performance of the proposed system was significantly improved compared with that of the conventional one, and the key problems in the field of solar-coal hybrid power generation have been solved.
Traditional biomass resources are rarely adopted by coal-fired power plants due to their seasonal availability and regional dispersion. A novel Arundo donax L. variety, characterized by high yield and robust adaptability to marginal lands such as tidal flats and coastal wetlands, offers a viable solution to these challenges. In this study, based on a 2×1 000 MW ultra-supercritical pressure once-through boiler, co-firing experiments of this novel Arundo donax L. were carried out, and its effects on thermal system, powder making system, and combustion characteristics of thermal power units were analyzed. The results show that the thermal power plant unit operation is stable after adding 15% Arundo donax L. particles. However, the stone coal discharge increases, the coal mill current is elevated by about 5%~10%, the maximum elevation of the coal mill inlet and outlet differential pressure is elevated by 10%~15%, the combustion intensity in the furnace decreases slightly. The low grindability index of Arundo donax L. is the key factor affecting the operation of the unit, and the study concludes that the torrefaction interval of about 250~300 ℃ is the best interval to improve the grindability index of Arundo donax L.
The ultra-supercritical double-reheat power generation technology has become an important development direction of thermal power generation technology due to its high efficiency and low emissions. A dynamic simulation model of the double-reheat boiler was established by the GSE software based on a 660 MW ultra-supercritical double-reheat coal-fired boiler with triple-rear passes. The variation laws of the main, primary, and secondary reheat steam parameters after disturbance by coal flow rate, feed-water flow rate, feed-water temperature and excess air coefficient under 100%THA working condition were calculated in detail. Moreover, the variation laws of steam temperature at the boiler outlet under the working conditions of 100%THA, 75%THA and 50%THA were compared. The simulation results show that the response of steam parameters at the boiler outlet is the slowest after feed-water temperature is disturbed, and the stability time is approximately 2 300 s under 100%THA working condition. The response of steam parameters at the boiler outlet is the fastest after excess air coefficient is disturbed, and the stability time is approximately 720 s. The stability times of the steam parameters at the boiler outlet are approximately 1 040 s and 1 250 s respectively after coal flow rate and feed-water flow rate are disturbed. In the initial stages of transient processes after coal flow rate, excess air coefficient and feed-water temperature are disturbed, there are short-term “reverse” changes in the steam temperature at the boiler outlet. In addition, the thermal inertia of the double-reheat boiler will increase as the boiler load decreases. The simulated dynamic characteristics of the double-reheat coal-fired boiler with triple-rear passes can provide the basis for further optimization of the unit operation control strategies.
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