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.

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.

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.

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.

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.

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.

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.

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.

The TiO₂ surface is functionalized with different concentrations of K₂CO₃ and polyethyleneimine (PEI), and in-depth research on CO₂ adsorption performance and mechanism is conducted. CO₂ low-temperature adsorbent was successfully prepared by ultrasonic impregnation method using K₂CO₃ and PEI as functionalized materials and commercial selective catalytic reduction (SCR) catalyst white embryo (porous TiO₂) as carrier. The physicochemical properties of the modified adsorbents were characterized using X-ray diffraction (XRD), differential thermogravimetry (DTG), Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results indicate that, K₂CO₃ and PEI activate the porous structure of TiO₂, enhancing the density of surface alkaline active sites. This enhancement facilitates the accommodation of PEI and K₂CO₃, exposes adsorption active sites, and promotes CO₂ diffusion and CO₂ adsorption. 50%PEI@TiO₂ introduces numerous active functional groups and alkaline amine sites, achieving a CO₂ adsorption capacity of 2.11 mmol/g. By measuring the CO₂ adsorption by 50%PEI@TiO₂ adsorbent and fitting to Langmuir and Freundlich adsorption isotherm models, it finds that CO₂ is mainly adsorbed physically, and van der Waals force plays a major role during adsorption. The optimal adsorption and desorption temperatures for CO₂ are 50 ℃ and 110 ℃, respectively. The cyclic experiment showed that, compared with PEI, K₂CO₃-loaded adsorbents exhibit greater stability, with a decrease in adsorption capacity of less than 10% after 30 cycles. These findings suggest that functionalized materials based on commercial SCR catalyst TiO₂ pellets hold promise for low-temperature CO₂ capture in industry flue gases.

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.