Deep participation in peak regulation is a fundamental issue in flexible peak regulation. The ability to operate coal-fired power units under ultra-low load plays a crucial role in China's pursuit of its energy goals. This study focuses on the performance analysis of a self-preheating pulverized coal burner with high coal concentration under ultra-low load conditions through simulations and experiments. A numerical comparison between the performance of a traditional swirl burner and a self-preheating burner is conducted using a 5 MW combustion test furnace. The results demonstrate that the self-preheating burner exhibits superior combustion stability and can maintain stable combustion even at an ultra-low load of 15 %. Additionally, the air distribution of the selfpreheating burner under ultra-low load conditions is investigated numerically. The results reveal that under 15 % load, primary air rate of 12.0 % and internal secondary air rate of 54.2 % enable the self-preheating burner to achieve stable combustion performance with a char burnout rate of 98.6 %. Furthermore, in the absence of separated over fire air (SOFA) conditions, the NOx emission level ranges from 150 to 165 mg/m3. Based on numerical results, the self-preheating burner is implemented in an industrial setting, specifically a 29 MW coalfired industrial boiler demonstration project. The results indicate that the self-preheating burner can achieve stable combustion at approximately 13 % load, with an average combustion efficiency of 93.24 %. The research validates the excellent performance of the designed self-preheating burner under ultra-low load conditions, which contributes to addressing the challenge of deep participation in peak regulation.

Nantun (NT) oil shale of ultra-high oil yield (>30%) is rare in the world, while the characteristics of this kind of oil shale are not widely reported. An oil shale pyrolysis experiment has been conducted in a tube furnace. The products of gas, oil and char are collected and analyzed on their yield and properties in the range of 450 to 650 degrees C. The oil yield remained above 30% in the range of 450 to 550 degrees C and decreased rapidly from 30.84% to 9.35% at 550 to 650 degrees C. The char yield drops from 66.14% to 57.94% as the pyrolysis temperature increases, and aliphatic hydrocarbon components in char have been cracked completely at 450 degrees C. The yield of pyrolysis gas rises as the pyrolysis temperature increases. CO accounts for the largest proportion of pyrolysis gas, with a volume fraction of over 70%. Based on the characteristics of pyrolysis products, an ultra-high-quality oil shale pyrolysis and utilization process and an Aspen Plus simulation model have been developed that provides estimated material and energy equilibriums for an industrial self-sustaining pyrolysis process to produce char and shale oil. This process can produce 0.61 kg oil and 0.29 kg char per kilogram of oil shale under self-sustaining conditions at 500 degrees C. In practical applications, the pyrolysis temperature is recommended to be 500 degrees C.

Biomass gasification technology offers a sustainable solution for managing agricultural waste, mitigating environmental pollution, and enhancing living standards. This work deploys Aspen Plus to simulate a downdraft gasifier with an integrated H-2 reforming module. The impact of key factors, including air equivalence ratio (ER), gasification system pressure, water vapor input, gasification agent temperature, and oxygen content, are considered. Specifically, optimal ER initially improved the gasification efficiency, with a peak followed by a decline. Water vapor addition elevated H-2 content, while increased gasifying agent temperature and oxygen concentration enhanced efficiency. However, the increased gasification pressure will lead to a decrease in gasification efficiency. Subsequently, the effect of reforming temperature, CaO, and water vapor input in the hydrogen production model was examined. An appropriate excess of water vapor and calcium oxide were crucial for maximizing H 2 concentration. As the reforming temperature increased from 200 degrees C to 600 degrees C, the H-2 concentration showed an initial increase and then stabilizes. However, beyond 600 degrees C, there was a rapid decline. Under optimal conditions (H2O/C > 1.3, CaO/C > 1.1, temperature 550-600 degrees C), the product gas generated during gasification and reforming processes achieved a high H-2 concentration of 98%-99%. These findings affirmed the substantial potential of biomass gasification in high-efficiency H-2 production.

The coal gasification process produces a large amount of coal gasification slag (CGS), which accumulates heavy metals from the raw coal. The CGS not only occupies land resources during long-term storage but also poses potential ecological pollution risks. In this study, eight different CGS samples from various regions of China were analyzed to determine their chemical composition and evaluate their environmental risks. Two leaching methods recommended by the Ministry of Ecology and Environment of China were employed to conduct leaching experiments, aiming to assess the hazardous waste level of CGS. The results indicated that the risk index of YL-FS and XJ-CS reached 101.87 and 87.15, respectively, classifying them as medium-risk materials. The remaining samples were categorized as low-risk materials. CGS itself is not classified as hazardous solid waste. The leaching results revealed that the concentration of Be in the leaching solution of NMG-CS and XJ-CS exceeded 0.005 mg/L, placing them in Class II of general industrial solid waste. The remaining samples exhibited minimal leaching toxicity and were classified as Class I general industrial solid waste.

A massive amount of coal gangue is produced during the mining and washing processes of coal, and it has become China's largest solid waste. Therefore, the disposal of coal gangue is extremely urgent. In this paper, a norvel coal gangue disposal technology is proposed, which is mainly divided into two stages: high temperature preheating pyrolysis and char combustion. A 300,000 tons/year demostration project of self-sustainable direct combustion decarbonization without auxiliary fuel is eatablished. The weight loss characteristics and kinetic analysis of ultra-low calorific value coal gangue in this process were studied by thermogravimetric analysis, compared with the normal calorific value coal gangue. The results show that the equipment has advantages and stability for the disposal of ultra-low calorific value coal gangue, and the removal rate of combustible components can reach 88.47 % on average. Based on analysis of TG data, it is determined that the best model describing stage 1, stage 2 and stage 3 of coal gangue pyrolysis process is D3, F2 and F2 model respectively, and the best model describing char combustion process is D2 model. Comparison experiments were carried out for ultra-low caloric value coal gangue under different heating rates and combustion temperatures. It is concluded that the residence time and combustion temperature in actual engineering have influence on the process, and it is suggested that the combustion temperature of char should be 800 similar to 900 degrees C. The research presented in this paper can provide innovative solutions for the disposal of coal gangue, and provide corresponding theoretical guidance.

Carbon quantum dots (CQDs) was prepared and supported on 2D Bi2MoO6 by hydrothermal method to prepare 2D Bi2MoO6/CQDs composite photocatalyst with up-conversion luminescence (UPCL) characteristics. The properties of 2D Bi2MoO6/CQDs were characterized by a series of characterization tools. Then, 2D Bi2MoO6 and 2D Bi2MoO6/CQDs catalysts were applied to photocatalytic Hg0 removal. The experimental results show that Hg0 removal efficiency of 2D Bi2MoO6/CQDs increased from 30.5% to 80.1% under visible light and from 7.2% to 26.4% under near-infrared light compared with 2D Bi2MoO6. The photostability test shows that 2D Bi2MoO6/CQDs nanocomposites could maintain high photostability after five photoreaction cycles. UPCL test proved that CQDs had the ability to absorb infrared light and emit visible light, thus expanding the light utilization range of composite catalyst. Moreover, in N2+6%O2+12%CO2+NO atmosphere, Hg0 removal efficiency of 2D Bi2MoO6/CQDs first dropped and then raised with the increase of NO concentration due to the simultaneous reduction and oxidation of NO in the system. Finally, the ESR test shows that the modification of CQDs could not only enhance light absorption rang of photocatalyst, but also promote the transfer of photogenerated carriers on the catalyst surface, thereby enhancing the photocatalytic Hg0 removal capability of the 2D Bi2MoO6/CQDs catalyst.

Co-firing of carbon-neutral biomass with coal is the most economic and promising technology to reduce CO 2 emission from coal combustion currently. Limited by the biomass distribution feature and collection cost in China, the biomass co-firing in large-scale coal power plants can only be at a small ratio of biomass. However, for the industrial boilers used for distributing energy system, it is able to co-fire biomass at a high ratio and even purely burn biomass. Biomass combustion in the grate furnace and circulated fluidized bed has been widely adopted, in contrast, the study and application of biomass co-firing in the pulverized coal industrial boilers of higher efficiency and automation degree at a high-ratio is rare. In this paper, the biomass high-ratio co-firing in a new developed pre-pyrolysis pulverized coal industrial boiler is studied. The effects of biomass co-firing ratio on temperature distribution, wall heat flux, specie distribution and NO x emission are discussed. The CFD modeling results show that biomass co-firing or even pure combustion follows the similar temperature and specie distribution of pure coal combustion. With the increase of biomass co-firing ratio, the combustion in the primary zone is strengthened, however, due to the higher moisture content in biomass, the flame is overall delayed, the oxygen consumption rate decreases, and the volatile and CO concentrations increases in the primary combustion zone. Because of the dual effects from flame delay and higher nitrogen content in biomass, with the increase of biomass co-firing ratio, the NO x emission increases first and then decreases. This study indicates that the pre-pyrolysis pulverized coal combustion technology is feasible to co-fire biomass at a high ratio and even hundred percent. When the nitrogen content of biomass is controlled, the NO x emission can be significantly reduced by biomass co-firing.

In the process of coal mining, washing and utilization, a huge amount of coal gangue (CG) is produced, which has become the largest solid waste in China. Large accumulation of CG is not only occupying the land area, but also leading to severe environment pollution. Therefore, the disposal of CG is extremely urgent in China. In this paper, a novelty process of CG pyrolysis is proposed, which can achieve self-sustaining treatment of CG. Based on the analysis results of pyrolysis experiments, the process simulation is established by Aspen plus software. By comparing the effects of CG type and pyrolysis temperature on the system, the stability and flexibility of the system is analyzed. The experiments results show that, with the increase of pyrolysis temperature, the oil and gases yields of CG pyrolysis increases. The simulation results show that under the same process conditions, the economy of the system strongly depends on the quality of CG, and the method proposed in this paper is more economical to treat ultra-low calorific value CG. The pyrolysis temperature also significantly affects the energy self-balance of the system, and the recommended pyrolysis temperature is about 600 celcius for industry process.

Coal gasification is one of the most promising clean coal technologies. However, gasification process also produces a huge amount of solid waste of high carbon content, named coal gasification fine slag. The coal gasification fine slag is mainly handled by landfilling, which is not only a hazardous pollution, but also wasting the energy from residual carbon. Developing a technology to utilize coal gasification fine slag and recover the residual carbon is becoming essential for an eco-friendly coal chemical industry. In this paper, the enrichment behavior of residual carbon in coal gasification fine slag by a spiral separator is studied. The raw coal gasification fine slag sample and separator products are characterized on particle size distribution, size-depending ash content, reactivity, micromorphology and porous structure. The experimental results show that the spiral separator is efficient to remove ash and enriched carbonaceous components in coal gasification fine slag by separating feed (100%) into concentrate (81.2%), middlings (8.8%), and tailings (10.08%), where the ash content in tailings is up to 90%, accounting for 18.5% of total ash in feeding. The beneficial product "concentrate" has a good distribution of size-depending ash content, that most combustibles are enriched in these particles of diameter >100 μm. After spiral separator, the concentrate products have a more pure and developed porous structure with the surface area increasing from 199.8 m2/g (feeding) to 231.8 m2/g, as well as a better combustion reactivity of lower ignition temperature compared with feedings. Accordingly, an economic and feasible combination process of spiral separator connecting sieve can produce an enriched-carbon product of ∼45% yield and ∼80% carbonaceous content. The Iodine adsorption ability of sieved products increases by 47.6% compared with feed, and reaches up to about half of industry activated carbon. The finally sieved concentrate products have a good market prospect as fuel and adsorbent.