Butterfly valves are widely used in industrial field, and under certain working conditions, strong unstable flow will occur in the butterfly valve and cause vibration in pipeline system. By taking the connecting pipe of the medium and low pressure cylinder of a 600 MW heating unit as the research object, the mechanism of unstable flow in the butterfly valve and the vibration of the connecting pipe was revealed through the combination of field measurement and steady numerical simulation. Then, based on the flow pattern optimization, a new type of butterfly valve with valve plate and diversion structure was designed, and the unsteady numerical simulation of the maximum vibration condition of the original butterfly valve and the optimized butterfly valve was carried out. The results show that, after adding the flow-guiding structure to the valve plate, most of the main steam flow moves along the middle of the steam inlet pipe of the low-pressure cylinder. This can effectively weaken the exciting force generated by unstable flow and suppress the vibration of the connecting pipe. The new butterfly valve proposed can be applied to suppress the vibration of the pipeline system with small opening of the butterfly valve.

The industrial production and urban residents’ lives have led to a large amount of wastewater and sludge, and the landfilling of sludge has caused severe ecological damage. To facilitate the large-scale disposal of municipal sludge, transform waste into valuable resources, and prepare low-carbon, low-cost thermal storage materials, an idea is innovatively proposed, in which the silicon carbide, boron nitride, and expanded graphite is added as thermal conductivity enhancers to enhance the thermal conductivity of sludge incineration ash/potassium nitrate composite phase change thermal storage materials (50% sludge incineration ash+50% potassium nitrate). The composite phase change thermal storage materials were prepared, and the effects of thermal conductivity enhancers on thermal performance of these materials were investigated. The results indicate that, the expanded graphite is not suitable as a thermal conductivity enhancer for sludge incineration ash/potassium nitrate composite phase change thermal storage materials. The addition of a thermal conductivity enhancer with a mass fraction of 2% is optimal for improving melting latent heat, with boron nitride performing better than silicon carbide. The samples with 2% boron nitride shows the most significant increase in thermal conductivity, rising by 65%, 93%, 117%, and 203% compared with samples SC3 (without thermal conductivity enhancers) at temperatures of 100 ℃ to 400 ℃, respectively. After undergoing 1 000 cycles of heating/cooling, the samples with 2% boron nitride have a latent heat of 35.29 J/g and a thermal storage density of 292.1 J/g, while the samples with 2% silicon carbide have a latent heat of 40.90 J/g and a thermal storage density of 334.9 J/g. The heat transfer rates for the samples with 2% silicon carbide and 2% boron nitride are 0.16 ℃/s and 0.17 ℃/s, respectively. This preliminary evidence demonstrates the feasibility of using silicon carbide and boron nitride as thermal conductivity enhancers for sludge incineration ash/potassium nitrate composite phase change thermal storage materials.

Improving the heat transfer efficiency between liquid lead-bismuth eutectic (LBE) and supercritical carbon dioxide (S-CO₂) is of great significance for advancing the development of advanced nuclear energy systems. The heat transfer performance of printed circuit heat exchangers (PCHE) with different channel structures (straight shaped, wing-shaped, S-shaped and Z-shaped) is investigated through numerical simulation. The results show that the thermal resistance on cold side of the heat exchanger is significantly higher than that on the hot side, with the average heat transfer coefficient of the hot side in straight-channel PCHE being 26.2 times that of the cold side. Under the condition of a fixed hot-side channel structure, the effects of different cold-side channel structures on PCHE heat transfer performance are explored. The results indicate that, compared with straight channels, the heat transfer of Z-shaped, S-shaped and wing-shaped channels increases by 23.3%, 22.2%, and 10.6%, respectively, while the specific pumping power improves by 1.48 times, 1.68 times, and 1.44 times, respectively. In addition, the dynamic performance of different PCHE designs when the cold-side flow rate increases by 20% is compared, revealing that the straight-channel PCHE has the shortest rebalancing time. The pressure drop loss is more significant than the improvement in heat transfer. These findings provide theoretical guidance for optimizing the design of LBE/S-CO₂ heat exchangers and contribute to enhancing the thermal efficiency of next-generation nuclear energy systems.

A novel power generation system integrating an organic Rankine cycle (ORC) with an air-cooled coal-fired power plant is proposed to achieve cascaded utilization of steam energy and enhance output power capability. Based on the efficient thermoelectric conversion characteristics of the ORC system at low and medium temperatures, the steam expanding to a certain level in the coal-fired unit is extracted to drive the ORC system for higher output power. This coupling scheme can achieve the multiple purposes of increasing output power, recovering exhaust steam waste heat and preventing air cooler icing in winter. Focusing on a 600 MW coal-fired power plant, thermodynamic performance evaluation has been carried out. The results show that, when the extraction flow rate is 160 kg/s, the thermal efficiency of the system at 50% THA, 75% THA and 100% THA loads increases by 3.48, 1.72 and 1.08 percentage points, respectively. The exergy efficiency increases by 3.38, 1.68 and 1.05 percentage points, and the coal consumption rate decreases by 27.72, 12.88 and 7.92 g/(kW·h), respectively. The heat recovery rate reaches 64.57%, 25.64% and 15.40%, respectively. This approach not only improves the performance of existing air-cooled coal-fired power plants, but also reduces coal consumption, and the research results can provide a way to improve the overall performance of power plants.

The ignition, burnout, and slagging performance of Baoqing lignite raw coal and its dried lignite with different moisture contents was experimentally investigated using an ignition furnace and one-dimensional furnace test platform. The results show that, the ignition temperature of Baoqing raw coal is 415 ℃, which is highly prone to ignition. Compared to the influence of moisture on ignition temperature, the effect of fineness on ignition temperature is more significant. At low loads, the water and steam react with the water gas of coke in the early stages of combustion, which has a significant impact on the consumption rate of coke. Due to its high moisture content, raw coal undergoes intense reactions during the initial combustion stage, resulting in a rapid decrease in mass fraction of combustible materials in fly ash and a stronger tendency towards slagging. However, excessive moisture is not conducive to the complete combustion of coal powder in the later stage of combustion. As the fineness of coal powder R₉₀ increases, the burnout rate of coal powder decreases. But overall, the burnout rate of both Baoqing raw coal and dry coal is above 99%, indicating the Baoqing coal is highly flammable, and the effect of oxygen on burnout rate is not significant.

Carbon capture, utilization, and storage (CCUS) technology has made significant progress in reducing CO₂ emissions in recent years, but its large-scale application is hindered by high energy consumption and high complexity. To enhance energy utilization efficiency, integrated of carbon capture and utilization (ICCU) has emerged as a promising research focus. ICCU process enables the capture and in situ conversion of CO₂ via dual-functional materials (DFM), converting the captured CO₂ directly into economically valuable chemicals with high efficiency. Compared with the conventional CCUS technologies, ICCU significantly simplifies processes such as desorption, compression, and transportation, demonstrating substantial potential for large-scale application. This review focuses on ICCU-methanation (ICCU-Met) process, first providing a systematic introduction to the process and a thermodynamic analysis of its feasibility. Then, the DFMs used in ICCU-Met are discussed intensively, their performance is compared in terms of CO₂ capture capacity, catalytic activity, and stability. The review also critically examines the scaling-up challenges of ICCU-Met technology in practical applications, including issues such as the effects of real-world flue gas conditions, reactor design, and economic feasibility. Finally, the review summarizes the developmental bottlenecks of this process and proposes potential research directions for the future.

Direct air capture (DAC) technology, a representative negative carbon emission solution, stands as a pivotal technology for achieving carbon neutrality. However, it still confronts challenges of high costs and energy consumption. The synergistic integration of DAC with carbon utilization technologies, namely transforming captured CO₂ into high-value products, can enhance carbon reduction efficiency while lowering lifecycle costs, rendering it a critical component in the carbon neutrality roadmap. This paper systematically reviews the classification and underlying principles of DAC, summarizes recent advancements and challenges in its integration with photovoltaic, electrochemical, and thermal CO₂ conversion technologies, and concludes with an outlook on the future development and applications of deep coupled DAC and carbon utilization.

At present, under the guidance of the national dual-carbon target strategy, carbon capture technology is being vigorously developed and has become an important technology to promote the utilization of carbon dioxide resources and significantly reduce greenhouse gas emissions. As fossil fuel stocks gradually decrease and the prices continue to rise, the search for new environmentally friendly green fuel has become a research hotspot. By coupling renewable energy such as wind energy and photovoltaic with carbon capture, the conventional fossil energy is fully utilized and converted into downstream products with high added value, such as syngas, methane, methanol, formic acid, and so on, which can achieve large-scale low-carbon emission reduction, reduce the gap of energy and chemical raw materials, increase economic income, and drive the strong growth of green industry, and is in line with the national green environmental protection strategic plan. Based on the analysis on the research status, mainstream technology routes, main equipment and demonstration projects, the direction of further research and development of the integrated carbon capture and transformation technology is pointed out, and the prospect of its industrial application is prospected.

Xinjiang Zhundong coal has abundant reserves and contains a relatively high content of alkaline earth metal elements. The high-calcium fly ash generated from its combustion serves as an excellent raw material for CO₂ sequestration. By adopting the atmospheric pressure direct wet carbonation process, research and optimization analysis were carried out on the carbonation of high-calcium fly ash, focusing on key parameters such as flue gas flow rate, temperature, and solid-liquid ratio. A kinetic model was constructed to determine the key factors and rate-controlling steps. Meanwhile, the performance of this process in chlorine removal and heavy metal removal was evaluated. It was found that, increasing the flue gas flow rate and reducing the solid-liquid ratio can effectively enhance the degree of carbonation per unit mass of fly ash. During the rapid carbonation stage (0~20 min), low temperature is beneficial for increasing the degree of carbonation, but the effect is not significant. In the rapid carbonation zone, the reaction of fly ash is mainly controlled by solid-film diffusion, with a correlation coefficient of 0.917 37 and an activation energy of 10.36 kJ/mol. After optimization by the response surface method, the optimal operating condition parameters are as follows: temperature of 57.1 ℃, flue gas flow rate of 2.86 L/min, and solid-liquid ratio of 200.0 g/L. Under these conditions, the average actual degree of carbonation reaches 30.2%. The chlorine content of the fly ash processed according to these parameters meets the requirements for reinforced products in the JC/T 409—2016 standard. For typical heavy metals such as arsenic and copper, the removal rates reach 88.4% and 55.6% respectively, indicating that this process has a certain detoxification ability. Therefore, the atmospheric wet carbonation of high calcium fly ash in Zhundong has great potential for application.

The ecological, environmental, and social issues caused by greenhouse gas emissions, mainly CO₂, are receiving increasing attentions and concerns from human beings. At present, the carbon sequestration technology using flue gas from thermal power plants as CO₂ source is still in the pilot and industrial development stage, but there is no standardized methodology and accounting method for carbon reduction benefits of the carbon sequestration process. Combining the industrialization practice of the first domestic “CCUS Technology Research and Demonstration Project for Carbon Dioxide Chemical Chain Mineralization Utilization in Thermal Power Plants” constructed and operated by a power plant, the carbon emission reduction benefits of the CCUS technology pathway for chemical chain mineralization utilization were calculated and evaluated using the life cycle assessment (LCA) carbon emission factor method. The annual CO₂ processing capacity of the above demonstration project is 1 364.56 tons, which can achieve a net reduction of 708.12 tons of CO₂, reaching a net emission reduction rate of 52%. By scaling up the annual processing capacity of demonstration project to 100 000 tons, the net reduction rate of CO₂ emission in the project can be increased to 76%. The research method has broad prospects for carbon reduction applications and can provide technical support for China to achieve carbon neutrality goals.