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Methanol-to-olefins (MTO), the most important catalytic process producing ethylene and propylene from non-oil feedstocks (coal, natural gas, biomass, CO 2 , etc.), is hindered by rapid catalyst deactivation due to coke deposition. Common practice to recover catalyst activity, i.e. removing coke via air combustion or steam gasification, unavoidably eliminates the active hydrocarbon pool species (HCPs) favoring light olefins formation. Density functional theory calculations and structured illumination microscopy reveal that naphthalenic cations, active HCPs enhancing ethylene production, are highly stable within SAPO-34 zeolites at high temperature. Here, we demonstrate a strategy of directly transforming coke to naphthalenic species in SAPO-34 zeolites via steam cracking. Fluidized bed reactor-regenerator pilot experiments show that an unexpectedly high light olefins selectivity of 85% is achieved in MTO reaction with 88% valuable CO and H 2 and negligible CO 2 as byproducts from regeneration under industrial-alike continuous operations. This strategy significantly boosts the economics and sustainability of MTO process. Methanol-to-olefins is hindered by rapid catalyst deactivation due to coke deposition. Here the authors demonstrate an approach of directly transforming coke to active intermediates to simultaneously recover catalyst activity and boost light olefins selectivity.

Based on the low-carbon transition needs of coal-fired boilers, this study conducted industrial trials of direct biomass co-firing on a 620 t/h high-temperature, high-pressure circulating fluidized bed (CFB) boiler, gradually increasing the co-firing ratio. It used compressed biomass pellets, achieving stable 20 wt% (weight percent) operation. By analyzing boiler parameters and post-shutdown samples, the comprehensive impact of biomass co-firing on the boiler system was assessed. The results indicate that biomass pellets were blended with coal at the last conveyor belt section before the furnace, successfully ensuring operational continuity during co-firing. Further, co-firing biomass up rates of to 20 wt% do not significantly impact the fuel combustion efficiency (gaseous and solid phases) or boiler thermal efficiency and also have positive effects in reducing the bottom ash and SOx and NOx emissions and lowering the risk of low-temperature corrosion. The biomass co-firing slightly increases the combustion share in the dense phase zone and raises the bed temperature. The strong ash adhesion characteristics of the biomass were observed, which were overcome by increasing the ash blowing frequency. Under 20 wt% co-firing, the annual CO2 emissions reductions can reach 130,000 tons. This study provides technical references and practical experience for the engineering application of direct biomass co-firing in industrial-scale CFB boilers.

Fluidized bed combustion of biomass requires maintaining stable properties of the inert bed material, which plays a key role in heat transfer, temperature stabilization and uniform fuel distribution in circulating fluidized bed (CFB) boilers. During long-term operation, quartz sand, i.e., the most commonly used inert material, undergoes physical and chemical degradation processes such as attrition, sintering and coating with alkali-rich ash, leading to changes in particle size distribution (PSD), deterioration of fluidization quality, temperature non-uniformities and an increased risk of bed agglomeration. This study analyzes quality management strategies for inert bed materials in biomass-fired CFB systems, with particular emphasis on the influence of PSD on boiler hydrodynamics and thermal behavior. Based on industrial operating data, sieve analyses and CFD simulations performed under representative operating conditions, a recommended mean particle diameter range of approximately 150–200 μm is identified as critical for maintaining stable circulation and uniform temperature fields. Numerical results demonstrate that deviations toward coarser bed materials significantly reduce solids circulation, promote segregation in the lower furnace region and lead to local temperature increases, thereby increasing agglomeration risk. The study further discusses practical approaches to bed material monitoring, regeneration and make-up management in relation to biomass type and ash characteristics. The results confirm that systematic control of inert bed material quality is an essential prerequisite for reliable, efficient and low-emission operation of biomass-fired CFB boilers.

The supercritical circulating fluidized bed (CFB) boiler, which combines the advantages of CFB combustion with low cost emission control and supercritical steam cycle with high efficiency of coal energy, is believed to be the future of CFB combustion technology. It is also of greatest importance for low rank coal utilization in China. Different from the supercritical pulverized coal boiler that has been developed more than 50 years, the supercritical CFB boiler is still a new one which requires further investigation. Without any precedentor engineering reference, Chinese researchers have conducted fundamental research, development, design of the supercritical CFB boilers independently. The design theory and key technology for supercritical CFB boiler were proposed. Key components and novel structures were invented. The first 600 MWe supercritical CFB boiler and its auxiliaries were successfully developed and demonstrated in Baima Power Plant, Shenhua Group as well as the simulator, control technology, installation technology, commissioning technology, system integration and operation technology. Compared with the 460 MWe supercritical CFB in Poland, developed in the same period and the only other supercritical one of commercial running in the word beside Baima, the 600 MWe one in Baima has a better performance. Besides, supercritical CFB boilers of 350 MWe have been developed and widely commercialized in China. In this paper, the updated progress of 660 MWe ultra-supercritical CFB boilers under development is introduced.

The continuous generation of agricultural, industrial, and urban waste necessitates effective waste management strategies. One promising approach is incorporating these residues as fillers in polymer composites. This study investigated the influence of coal processing-derived fillers, specifically microspheres and fluidized-bed combustion fly ash, on the structure and properties of composite rigid polyurethane foam. Polyurethane foams were produced through manual mixing and casting, with composite foams containing a combination of 5% microspheres and 5–15% fly ash by weight. The analysis of the samples investigated their structural, thermal, and mechanical properties. The samples consistently displayed predominantly pentagonal, regularly shaped cells. Infrared spectroscopy revealed no observable chemical bonding between the matrix and filler materials. Mechanical analysis was performed to evaluate the materials’ characteristics, revealing significant variations in compressive strength and Young’s modulus values. The results indicate that the addition of fillers did not impact the cellular and chemical composition of the polyurethane matrix. Furthermore, the composite material specimens were subjected to accelerated aging in a laboratory dryer and outdoor exposure in order to assess their thermal stability. This analysis revealed notable alterations in both the cellular composition and mechanical properties of the composite foam materials.

This study investigates the effects of the co-combustion of coal and açai seed in circulating fluidized bed (CFB) boilers, highlighting the increase in thermal efficiency and relevance of a less-polluting source of energy. Using the computer software 1.5D CeSFaMB™® v4.3.0, simulations of the co-combustion process of coal and biomass were carried out in a CFB boiler, obtaining results such as the temperature profile, boiler efficiency and emissions. The work acquired data regarding the equipment in real operational conditions, consisting of the fundamental geometric and operational parameters used in the simulation campaign. The thermal and chemical properties of the fuels were analyzed by carrying out proximate, ultimate, heating value, particle size and specific mass analyses. The model validation was achieved by simulating the boiler in its real operating conditions and comparing the obtained results with the real data; the obtained error was below 10%. Simulations with different fractions of açai seed for energy replacement (10% and 30%) were carried out. As a result, an increase in the average temperature of the bed was observed, highlighting the region immediately above the dense bed. An increase in boiler efficiency was verified from 56% to 85% with 10% açai and to 83% with 30% açai seed. Decreases in SO2 and CO emissions with the insertion of açai were obtained, showing that co-combustion is more complete, while CO2 emissions were increased due to the higher quantity of fuel inserted into the equipment. The fossil CO2 emissions were reduced.

Microencapsulation is an advanced food processing technology, using which any compound can be encapsulated inside a particular material, making a tiny sphere of diameter ranging from 1 μm to several 100 μm. Microencapsulation is done for protecting the sensitive compounds and, hence, ensuring their safe delivery. The compound or active material which is encapsulated is called the core and the material which is used for encapsulating is called the encapsulant. Encapsulants can be either polymeric or nonpolymeric materials like cellulose, ethylene glycol, and gelatin. There are several techniques used for microencapsulation. Fluidized bed coating, spray cooling, spray drying, extrusion, and coacervation are few to be named. The selection of a particular technique depends upon the properties of the core material, encapsulant, and different properties and morphology of the capsules desired. The characterization and optimization of efficient and successful encapsulation can be done by studying the encapsulation efficiency and various properties of the capsules like morphology, size, hydrophobicity, hygroscopicity, solubility, surface tension, thermal behavior, and mechanical properties. Microencapsulation is a technology that is extensively used in foods, whether as a fortifying tool or as a mode for the development of a functional food. Based on the fundamental understanding of encapsulation and latest research and findings from literature, this review critically analyses and brings together the utilization of this particular technique in foods, different methods used for encapsulation, different properties of the capsules which result from the different techniques adopted for microencapsulation and different release mechanisms used for delivering the compounds. Different techniques of microencapsulation: (a) spray drying; (b) fluidized bed coating; (c) coacervation; (d) extrusion

Comprehensive control of greenhouse gas emissions and response to climate change are concerns of countries around the world to protect living homes. The steel industry is responsible for over 10% of global CO 2 emissions, with approximately 80% of these emissions coming from the ironmaking process. Great efforts have been made in both blast furnace (BF) and non-blast furnace ironmaking processes to reduce emissions. Fluidized bed technology has become a crucial method used to process iron ore powder in non-blast furnace ironmaking, such as smelting reduction and direct reduction. This paper introduces the working principle and several typical working states of fluidized bed (FB) technology to clarify the key to fluidized bed process operation. And different kinds of fluidized bed ironmaking processes in recent decades are compared, including FIOR, DIOS, Circored, Circofer, FINMET, HIsmelt, FINEX, etc. Finally, the possible problems and solutions in the future development of fluidized bed ironmaking are analyzed. Hope that this work can contribute to the advancement of basic theory and technology research in fluidized bed reduction, and provide support for hydrogen metallurgy in the steel industry. Graphical Abstract

The gas-solid fluidized bed with liquid spray has been used in the industrial processing. Investigating the flow behaviors is crucial for optimizing the fluidized bed reactor. This research experimentally investigated the effects of gas velocities, temperature, height-to-diameter ratios, and solid-liquid ratios on flow characteristic in a spray-fluidized bed. The findings revealed that as the gas velocities increased, the standard deviation of pressure pulsation exhibited an upward trend, while the fluidization index initially decreases before subsequently increasing, achieving optimal fluidization quality at a velocity of 0.25 m/s. As the temperature rises, the trends of the pressure pulsation show contrasting trends before and after adding liquid, with the lowest fluidization index observed at 510 °C. An increased height-to-diameter ratio contributes to a rise in the pressure pulsation, and the fluidization index first decreases and then tends to be stable. Additionally, as the solid-liquid ratios increase, the pressure pulsation also rises after adding liquid, and the entrainment rate was negatively correlated with the average particle size of the remaining particles in the bed. The findings elucidate liquid-phase effects on gas-solid dynamics, directly informing strategies to optimize chlorination efficiency of the carbonized slag and improve reactor stability.

Synthetic polymers-based controlled release urea (CRU) leaves non-biodegradable coating shells when applied in soil. Several alternative green materials are used to produce CRU, but most of these studies have issues pertaining to nitrogen release longevity, process viability, and the ease of application of the finished product. In this study, we utilized tapioca starch, modified by polyvinyl alcohol and citric acid, as coating material to produce controlled release coated urea granules in a rotary fluidized bed equipment. Response surface methodology is employed for studying the interactive effect of process parameters on urea release characteristics. Statistical analysis indicates that the fluidizing air temperature and spray rate are the most influential among all five process parameters studied. The optimum values of fluidizing air temperature (80 °C), spray rate (0.13 mL/s), atomizing pressure (3.98 bar), process time (110 min), and spray temperature (70 °C) were evaluated by multi-objective optimization while using genetic algorithms in MATLAB®. Urea coated by modified-starch was double coated by a geopolymer to enhance the controlled release characteristics that produced promising results with respect to the longevity of nitrogen release from the final product. This study provides leads for the design of a fluidized bed for the scaled-up production of CRU.