Ammonia, as a low-carbon fuel, has important application prospects in the field of industrial combustion. However, the dynamic characteristics of liquid ammonia gasification process are complex, and conventional mechanism models are difficult to meet high-precision control requirements. To address the problem of unstable control caused by insufficient modeling accuracy in the liquid ammonia gasification process in ammonia combustion systems, a dynamic modeling method that combines mechanism with data fusion is proposed. By establishing a nonlinear mechanism model based on thermodynamic laws, and combining with a data-driven model based on recursive fuzzy C-means (RFCM) clustering and recursive least square (RLS) algorithm, a hybrid dynamic model with adaptive weight optimization is constructed. On this basis, decoupling control strategies are developed to achieve precise control of the gasification systems. Experimental verification shows that, the proposed model significantly improves the prediction accuracy of the gasification process, and the decoupling control scheme based on this dynamic model achieves stable ammonia supply, verifying the effectiveness and engineering practicality of the dynamic model that integrates mechanism and data for the control system. This method provides an effective solution for intelligent control of ammonia fuel combustion systems and has promotional value for the engineering application of clean energy technology.

In the context of carbon peak and carbon neutrality, renewable power to ammonia (RePtA) technology has garnered widespread attentions due to its ability to scale up the consumption of renewable energy and green hydrogen. However, the hydrogen production from renewable energy in RePtA systems exhibits significant volatility, posing challenges to stable operation of the Haber-Bosch ammonia synthesis process. To address this issue, a discrete multi-steady-state flexible load operation strategy for ammonia synthesis process is proposed. A two-stage optimization model for capacity configuration and coordinated chemical operation scheduling is established using the PSO-MILP algorithm. A case simulation analysis was conducted on a demonstration project under construction in Inner Mongolia, and the technical and economic performance of three different flexible schemes was compared. The result indicates that, compared with the conventional steady state schemes, the discrete multi-state flexible operation strategy’s economic efficiency improved significantly after capacity and operation coordination optimization, with annual revenue increased by 67 150 000 yuan. Compared with the fully flexible operation strategies, the new strategy significantly enhances the stability of the ammonia synthesis process, reducing production load volatility by 78.16%. The proposed optimization model can balance the investment economic efficiency and operational safety of the RePtA system, and its findings are expected to provide some guidance for actual production operations.

To tackle the challenges associated with the poor combustion performance of ammonia fuels and the high NO_x emissions in exhaust gases, experimental research on enhancing ammonia combustion through the use of a swirling burner combined with a gliding arc plasma generator was carried out. The effects of various combustion enhancement methods, including methane-assisted combustion, plasma-assisted combustion, and plasma-coupled methane-assisted combustion, on the combustion characteristics of NH₃ swirling flames and the generation of NO were investigated. The experimental results indicated that, compared with the methane-assisted combustion, both plasma-coupled methane-assisted combustion and plasma-assisted combustion significantly enhanced the stability of ammonia combustion. This improvement was evidenced by a substantial expansion of the stable combustion limit range of the NH₃ swirling flame, enabling normal combustion within an NH₃/Air equivalence ratio range of 0~5.0. In comparison to single methane-assisted or plasma-assisted combustion, plasma-coupled methane-assisted combustion (with a plasma power of 0.8 kW and a methane flow rate of 1 L/min) significantly enhanced the active species H_α and OH generated by the discharge, thereby strengthening the chemical effects in plasma-assisted combustion. Under these conditions, the NO emission mass concentration in the exhaust gases rapidly decreased from over 7 000 mg/m³ to approximately 100 mg/m³ as the NH₃/Air equivalence ratio was increased from 0.6 to 0.8. Furthermore, the gas temperature under these conditions was only slightly lower than that observed in pure plasma-assisted combustion, where the flame temperature of ammonia combustion could reach up to approximately 2 030 K.

The use of large-scale coal-fired power units mixed with refused derived fuel (RDF) can reduce carbon emissions and solve the problem of waste management. To verify the feasibility of co-firing RDF in coal-fired boilers, initial tests were conducted using a one-dimensional furnace to determine the maximum allowable proportion of RDF. Then, pilot-scale tests were carried out on a 4 MW boiler to study the effect of RDF co-firing on coal grinding, combustion, pollutant emissions, and slagging and fouling. The results showed that, when the co-firing ratio of RDF was less than 10% (mass ratio), the mass concentration of dioxins in the flue gas, and dioxins and heavy metals in the ash residue were all below the pollutant control standards. When 10% of RDF was co-grounded with coal in a medium speed mill, the fineness of R₉₀ increased to 27.2%. When the coal and RDF were mixed and co-fired, the flame temperature and NO_x formation concentration decreased, the slagging in the combustion air zone increased, while the horizontal flue fouling changes were relatively minor, and the combustible content in the bottom slag increased to about 15%. The research will provide reference for co-firing RDF in coal-fired boilers.

The technology of co-firing ammonia with natural gas has become a global research focus due to its significant potential in reducing carbon emissions. During the combustion process, ammonia faces challenges such as difficulty in ignition, slow flame propagation speed, and susceptibility to blow-off. The addition of natural gas can significantly improve these combustion characteristics, thereby promoting the widespread application of ammonia fuel and opening up new avenues for the development of clean energy. Firstly, the application potential of natural gas-ammonia co-firing technology is evaluated from the perspectives of technical and economic feasibility, and its positive significance in the energy transition process is analyzed. Then, drawing on research findings at the reaction kinetics level, the chemical reaction mechanisms of ammonia and natural gas co-firing are elucidated. On this basis, the latest domestic and international research progress in this field is reviewed, covering experimental studies, numerical simulations, and low-NO_x stable combustion control strategies. It is pointed out that significant discrepancies still exist among different mechanism models in terms of simulation accuracy and experimental prediction universality. Future research needs to combine multi-scale simulations to develop more adaptable ammonia combustion prediction models that can balance accuracy and efficiency. Finally, the challenges encountered in the practical application of natural gas-ammonia co-firing technology are summarized, and future research directions are proposed, aiming to provide a theoretical basis and practical guidance for the in-depth development of this technology.

Co-combustion of biomass and coal can significantly reduce the pollutants and carbon emissions. However, the pollutants emission, ash characteristics and their influence factors during co-combustion of coal and biomass are still obscure. A micro-fluidized bed reactor was used to investigate the co-combustion of rice husk (RH) and bituminous coal (SC). The effects of combustion temperature, atmosphere and blending ratio on the emission characteristics of NO, SO₂ and ash were studied. The results indicated that, with the increase of temperature, the mass concentration of NO emissions during co-combustion rose at first and then fell, while the SO₂ emissions mass concentration gradually increased. High temperature would promote the interaction of minerals in the ash, generating Na₂Al₂SiO₆ and lowering the melting point of the co-combustion ash. In oxygen-deficient atmosphere, NO and SO₂ emission mass concentrations increased with the O₂ volume fraction. In oxygen-enriched atmosphere, the NO emission mass concentration gradually decreased as the O₂ volume fraction increased, while the SO₂ emission mass concentration increased at first and then decreased. The influence of reaction atmosphere on the main composition and crystal structure of the co-combustion ash was relatively minor. NO and SO₂ emissions during co-combustion can be effectively reduced due to the addition of RH. As the RH blending ratio was increased, Ca₃Al₂O₆ in ash tended to form low-melting-point compounds with SiO₂, leading to a noticeable melting phenomenon.

Aiming at the difficulties in renewable energy consumption and the demand for low-carbon development in the integrated energy system, an optimal scheduling method considering the joint operation of hydrogen-doped gas-fired units with hydrogen-doped and ammonia-doped coal-fired units is proposed. Firstly, to account for the uncertainty and correlation of wind and solar power outputs, a joint wind-solar output modeling approach based on the Frank Copula function is adopted. Typical wind-solar scenarios are generated through marginal distribution fitting using kernel density estimation, Monte Carlo sampling, and K-means clustering, thereby enhancing the robustness of the scheduling model. Meanwhile, energy conversion models for power-to-hydrogen and hydrogen-to-ammonia processes are developed to enable the efficient transformation of renewable energy into hydrogen and ammonia. Secondly, the refined operation model of hydrogen-doped combustion of gas-fired units and ammonia-doped combustion of coal-fired units is constructed in response to the demand for low-carbon transformation of conventional fossil energy units, so as to optimize the synergistic utilization of hydrogen and ammonia fuels in the power generation process. Then, the optimal dispatching model is constructed by combining with the laddering-type carbon trading mechanism with the goal of minimizing the total operation cost of the system, which is to minimize the total cost of the system. Moreover, the optimal scheduling model is constructed with the objective of minimizing the total operating cost of the system in combination with the stepped carbon trading mechanism and solved by the CPLEX solver. Finally, different scenarios are set up and comparative analysis are carried out. The results indicate that, the introduction of hydrogen-to-ammonia conversion, building upon hydrogen energy utilization, significantly mitigates wind and solar power curtailment within the system. The combined operation of hydrogen-doped gas-fired unit and ammonia-doped coal-fired unit leads to concurrent reductions in both total operational costs and carbon emissions. The study provides a reference for the development of decarbonization of integrated energy systems.

In the context of “carbon peak, carbon neutral”, how to utilize biomass fuel safely, efficiently and environmentally friendly has become a hot research issue in the industry. The research progress of biomass fuel fluidized bed combustion technology both domestically and internationally was summarized based on the extensive practical engineering experience in fluidized bed combustion, providing a comprehensive overview of progress in biomass fluidized bed combustion power generation technology from an engineering perspective. The analysis compares the characteristics and problems of biomass boilers, with particular emphasis on the research and application status of biomass utilization in circulating fluidized bed. In addition, the combustion characteristics of biomass fuels, NO_x pollutant emission control, chlorine corrosion, and ash deposition and slagging issues caused by alkali metals in fluidized bed combustion were discussed. The reaction mechanisms in each process were described, and the future development directions of related technical issues were forecasted.

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.

The “double high” characteristics of new power system make its frequency stability face a huge challenge. Energy storage assisted thermal power unit frequency regulation technology has become a key core technology to ensure the stable operation of the new power system. The mainstream form of energy storage used in this technology, lithium battery storage, suffers from short lifespan and poor safety in use. The features of supercapacitor energy storage like high power, long cycle life, and high security, are highly compatible with the energy-storage requirements of frequency regulation of the energy storage assisted thermal power unit, but the supercapacitor’s response to the continuous unidirectional command is poor. Therefore, it is necessary to explore the technical route of hybrid energy storage to achieve complementary advantages of the two types of energy storage. The hybrid energy storage capacity configuration of supercapacitor and lithium battery was studied, the energy storage capacity configuration method based on the actual AGC frequency regulation command was designed, considering the characteristics of power-type energy storage devices and energy-type energy storage devices. Moreover, the frequency regulation performance and economy of three typical capacity configuration schemes were compared, and the optimal scheme was determined. Finally, engineering verification was carried out. The actual operation data show that, the supercapacitor hybrid energy storage system can improve the frequency regulation performance of the thermal power unit by 59.77%, extend the service life of the lithium battery to 3.6 times, and improve the system economy.