Based on the computational particle fluid dynamics (CPFD) numerical simulation method, the study takes the 660 MW supercritical circulating fluidized bed (CFB) boiler in Pingshuo, Shanxi as the research object. A full-loop model of the furnace is established and numerically simulated. On the basis of the parameters of the actual furnace, the material distribution characteristics of six cyclone separators are investigated. By altering the ratio of primary to secondary air, the uniformity of primary air, and the uniformity of secondary air, the effect of operational parameter changes on the gas-solid flow field within the furnace and the material distribution at the cyclone separator inlets is analyzed. The results indicate that the distribution characteristics of particles within the furnace lead to a distribution feature of particle mass flow rate at the cyclone separator inlets, which is “high on both sides and low in the middle”. When the total air volume is constant, a larger ratio of primary to secondary air can reduce the deviation in particle mass flow rate at the cyclone separator inlets. The uniformity of air distribution for both primary and secondary air in the furnace also affects the particle mass flow rate distribution at the cyclone separator inlets. The deviations in particle mass flow rate at the inlets of the six cyclone separators reach their minimum when the wind speed deviation at the middle air distribution plate is 10% and the deviation in the middle secondary air volume is 5%, respectively.

Circulating fluidized bed (CFB) boilers are characterized by high thermal inertia and strong heat storage capacity, enabling banked fire and near-zero output peak shaving. However, there is limited experimental research on banked fire and peak regulation in large-scale CFB units, with a lack of studies on key parameter variations and control strategies during this process. In this study, a banked fire and peak regulation test was conducted on a supercritical 350 MW CFB boiler to investigate the evolution of critical parameters during shutdown and propose optimization strategies for boiler feedwater flow rate and integrated turbine valve position control. These optimizations aim to maximize the peak shaving duration while ensuring operational safety. Experimental results demonstrate that the optimized supercritical CFB unit achieved 85 minutes of shutdown peak regulation with a load of 5~8 MW. Throughout the test, the boiler maintained dry operation, while the main and reheat steam temperatures decreased from 566.0 ℃ and 553.0 ℃ to 482.0 ℃ and 472.0 ℃, with average cooling rates of 0.99 ℃/min and 0.95 ℃/min, respectively. The average bed temperature declined from 875.8 ℃ to 730.9 ℃ at a rate of 1.70 ℃/min. During the test, the maximum exhaust temperature of the high-pressure cylinder reached 380.0 ℃, with the steam temperature at the regulating stage exceeding that of the cylinder inner wall. The wall temperature deviation at the outlet of the boiler water-cooled walls and mid-partition walls gradually decreased, peaking at 97.5 ℃. These findings confirm the feasibility of hour-level shutdown peak regulation in supercritical CFB units and provide a reference for engineering applications of similar units.

With the rapid expansion of new energy power generation capacity in China, the insufficient load regulation capability of coal-fired power plants has become increasingly evident. In order to explore the start-stop peak regulation capability of supercritical circulating fluidized bed (CFB) power units, a 350 MW supercritical CFB unit was taken as the research object, and experimental studies on banked-fire hot standby and rapid start-stop operations were conducted. The experimental results demonstrated that the supercritical CFB unit can rapidly reduce its load to near zero (with an average load change rate of about 10%Pe/min) during bank firing, and then maintain hot standby for 108 minutes. After banked firing, the boiler quickly switched to wet-state operation, with the main steam pressure decreasing rapidly at a rate of 0.13 MPa/min. By reasonably controlling the feedwater flow, the working fluid temperature and wall temperature of the water-cooled walls and water-cooled panels were kept stable. The heat released from the combustion of residual carbon caused the bed temperature to decrease slowly during banked firing, which also provided favorable conditions for re-ignition. During the load lift phase, the unit could be quickly started, with NO_x emission mass concentration reaching an instantaneous peak of 101 mg/m³, while the hourly average was stable below 50 mg/m³. Throughout the entire experimental period, SO₂ emission mass concentration was consistently below 35 mg/m³, and pollutant emissions met the ultra-low-emission requirements. All parameters of the steam turbine and generator remained within normal ranges during the hot standby and startup/shutdown. The rapid decline in main steam pressure and the low superheat of the main steam temperature were the main factors limiting the duration of banked firing in this experiment. The relevant research work provides a reference for the start-stop peak regulation of higher-parameter supercritical and ultra-supercritical CFB units.

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.

By taking a 150 000 tons/year carbon dioxide capture system in a power plant as the research object, a comprehensive analysis was conducted for its water usage, water consumption and water balance. Moreover, the water balance of the carbon capture system was experimentally studied and compared under different loads. The experimental results show that, the main problem in the current capture system’s water balance is that the outlet temperature at the top of the absorption tower is higher than the inlet flue gas temperature. Under high-load conditions, the reaction heat inside the absorption tower is relatively large, resulting in an excessively high exhaust steam temperature and a significant increase in system water consumption. After the outlet temperature of the absorption tower was reduced from 54 ℃ to 43 ℃, the system water consumption reduced by approximately 86.7%, demonstrating remarkable energy-saving effects. In light of this, combined with the actual operation situation, suggestions are put forward to further improve the temperature field of the absorption tower and reduce the outlet temperature of the absorption tower by adjusting the circulating water volume and enhancing the heat transfer efficiency of the lean solution cooler and the tail gas scrubber. The experimental results can provide guidance for efficient and economical operation of carbon capture systems.

Carbon capture, utilization and storage technology is an important way to realize the carbon peaking and carbon neutrality goals in China. Among them, the non-aqueous phase absorbents have great energy-saving potential, and it is suitable for the existing mixed amine reactor, which has a large development potential. However, there are still problems such as high viscosity of CO₂ saturated solution and low circulating load. In this regard, a non-aqueous absorption system with low viscosity and regeneration temperature was constructed using secondary amine MCA as the absorbing component and EG as the organic solvent. The absorption and regeneration performance of MCA/EG was investigated. The results showed that, the absorption load of 3 mol/L MCA/EG solvent was up to 2.14 mol/L, and the viscosity was only 44.19 mPa∙s. Under the condition of absorption at 40 ℃ for 30 min and regeneration at 80 ℃ for 25 min, the cyclic load was as high as 0.98 mol/L, which is 1.46 times of the cyclic load of 30% MEA/H₂O solution at 105.5 ℃. The reaction heat of the absorbent was measured to be -82.85 kJ/mol by C80 microcalorimeter, which was lower than that of the MEA/H₂O solution. The reaction mechanism of CO₂ capture by MCA/EG was explored by ¹³C NMR and quantum chemical calculations. It was found that the stability of the reaction products was reduced for the steric hindrance effect of MCA. The carbamates transform into alkyl carbonate by reacting with EG to realize the regeneration at low temperatures. MCA/EG can realize the stable operation of non-aqueous phase absorbent and expand the scope of waste heat utilization in absorbent regeneration, which has a great advantage of energy reduction.

Taking CO₂ absorption by amine solutions in industrial-scale spray towers as the research object, a computational fluid dynamics (CFD) model is established to describe the gas-liquid two-phase flow, interphase heat and mass transfer, and chemical reaction process in industrial-scale spray scrubber, based on the Euler-Lagrange method. The reliability of the CFD model is validated by experimental data of CO₂ absorption by monoethanolamine (MEA) solution. On this basis, the fundamental laws of heat and mass transfer and chemical reactions accompanying the CO₂ absorption process, as well as the effects of the absorbents’ chemical composition, gas-liquid phase flow characteristics, and operating pressure on the efficiency of CO₂ removal in a spray tower were investigated. The numerical results indicate that, the volume fraction of CO₂ in flue gas decreases with the increase of scrubber height, while both the gas temperature and water vapor pressure firstly increase and then decrease with the increase of elevation. With the increase of CO₂ load in lean solution from 0.1 to 0.4, the highest gas temperature in the scrubber declines from 70 ℃ to 54 ℃. The overall decarbonization efficiency for the spray scrubber significantly decreases when the load of lean solution is greater than 0.25. When the superficial gas velocity is greater than 2.5 m/s, the enhancement of increased mass transfer specific interface area on CO₂ absorption is restricted ascribed to the declines of gas residence time and mass transfer coefficient. For the decrease of operating pressure in spray scrubber from 101 kPa to 70 kPa, the CO₂ removal efficiency decreases by about 15.9 percentage points.

Due to the low-carbon transformation requirement of domestic coal power units in the “carbon peak and carbon neutrality” situation, exploring a new industrialization way in solid adsorption CO₂ capture technology on CCUS, and developing a new solid chemical sorbent to capture CO₂ from coal-fired flue gas, are important for realizing large-scale application of such technology. Current researches on solid adsorption CO₂ capture technology in China mainly focus on the theory level. This study systematically reviews and analyzes the research progress on solid sorbent materials at low, medium and high temperatures, points out the directions for further research, and identifies the research content needed for scaled application. A typical high-temperature calcium-based sorbent is used as an example to analyze the industrial applications of the entire process, including the sorbent preparation, sorbent scaling up, sorbent granulation and molding, reactor design, and CO₂ capture system verification for calcium looping. This study can provide references for aspects including further key technology research and breakthroughs, the construction of a full process for solid adsorption CO₂ capture with high activity and low energy requirement, and the realization of the large-scale application of solid adsorption CO₂ capture technology.

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.