Research Progress on Key Technologies for Coupled Combustion of Coal and Solid Waste in Coal-Fired Unit

[Introduction] The co-combustion of coal and solid waste can not only realize the energy recycling of solid waste, but also is one of the paths to realize carbon emission reduction of coal-fired power generation. [Method] This paper reviewed the study on co-combustion of coal and solid waste in coal-fired power plants, and mainly introduced the combustion application and technology development of co-combustion of coal and different solid wastes based on the current mainstream power plant boiler as a reactor; Evaluated the development of co-combustion technology of coal and solid waste from the perspectives of fuel economy, fly ash characteristics of mixed fuels, pollutant emissions, and carbon tax; Finally discussed the characteristics of direct and indirect mixing technologies. [Result] Direct co-combustion of coal and solid waste is required to minimize the impact on boiler operation, especially the emission of gas pollutants, the impact of fly ash on heat transfer surfaces, and the harmless disposal of fly ash. Indirect co-combustion can avoid the influence of mixed fuel combustion on the furnace, but requires high hardware cost investment and more complicated coupling technology. The oxygen-enriched combustion technology still needs to optimize the existing boiler structure to improve the applicability of the technology. [Conclusion] The direct co-combustion is better than the indirect co-combustion considering the realizability and the cost, and the extensive adaptability of circulating fluidized bed fuel is conducive to the application of direct co-combustion technology of coal and solid waste. With the development of the oxygen- enriched combustion technology based on the circulating fluidized bed, it is more conducive to realize carbon emission reduction in coal-fired power plant

The New Structure Design and Analysis of Energy Storage of Flywheel of Split Rotor

The braking of the rail transit train consumes a great quantity of energy, and the thermal energy produced in the process of braking can affect the normal operation of the transit train. Thus recycling the braking energy becomes a research hotspot of urban rail train. This paper made an overall analysis of regenerative braking process, the rationale, and the main features and then put forward the optimizing the structure of the composite flywheel concept and design calculation method. This paper also designs a new flywheel structure which can be applied on urban rail operating system. The new flywheel structure should be checked by finite element method and the radius of the rotor should be defined under the condition of meeting the requirements of carbon fiber material strength. Meanwhile, compared with the solid flywheel under the same condition, analysis shows that the maximum rotary inertia of the new flywheel and the quality energy density increased, and the discharge depth also perks up

Bending Properties of Short-Cut Basalt Fiber Shotcrete in Deep Soft Rock Roadway

To study the effect of short-cut basalt fiber (BF) on the bending and toughening properties of shotcrete, bending toughness tests of short-cut BF shotcrete slabs with different volume fractions were carried out. A transparent soil model and Scanning Electron Microscopy (SEM) were used to observe the distribution of BF with different volume fractions and analyze the toughness enhancement mechanism of basalt fiber shotcrete. The supporting effect of basalt fiber shotcrete with different volume fractions was verified by an underground engineering test. The test results show the following: (1) when the fiber content is within 3∼4.5 kg/m3, the distribution of BF in transparent soil is uniform, and it does not easily agglomerate, which is beneficial to improving the bending toughness of shotcrete. (2) The shotcrete slab with 4.5 kg/m3 fiber content had the best reinforcing effect. Compared with the control group, the peak load and absorption capacity increased by 56.67% and 636.96%, respectively, and the maximum crack width decreased by 32.10%. (3) The SEM analysis indicated that the basalt fibers distributed randomly and evenly in the concrete, which can form a three-dimensional spatial skeleton with a stable structure. Excessive fiber incorporation can increase fiber agglomeration during stirring and spraying. (4) The support results of an underground engineering test show that, in 35 days, short-cut basalt fiber shotcrete with 4.5 kg/m3 fiber content is better at restraining the surrounding rock than shotcrete with other fiber contents. BF has the properties of crack resistance, bridging, and toughening for shotcrete and can significantly improve the ability of shotcrete to restrain surrounding rock deformation. As a new type of fiber, BF has great significance in deep soft rock underground engineering

Study on the Stress Field and Crack Propagation of Coal Mass Induced by High-Pressure Air Blasting

High-pressure air blasting (HPAB) is one type of physical blasting technique that enhances the extraction rate of coalbed methane by impacting the coal mass with high-pressure gas to create cracks within it. First, based on the physical and mechanical parameters of the simulated coal rock mass, the RHT constitutive model of the coal rock mass was established, and its parameters were determined. Then, the laws of crack propagation and stress wave decay in coal induced by high-pressure air blasting were revealed by comparing the effect with that of equivalent explosive blasting. Next, the HPAB experiment was simulated to explore the coal crack propagation law under in-situ stress conditions. Finally, the HPAB experiment was carried out and the results of this experiment were compared with the numerical simulation results. The results indicate that the crack propagation induced by high-pressure air blasting is considered as two major stages, i.e., the crack initiation and crack propagation stage induced by the stress wave and the crack stable propagation stage induced by the duration high-pressure gas. In the case of equal energy, the peak stress wave of high-pressure gas is smaller, decays more slowly and has a longer action time, compared to explosive blasting. Therefore, the number of initial random cracks in coal mass induced by high-pressure air blasting is less, and the range of crack propagation induced by high-pressure air blasting is larger. When λ = 0 (λ is the ratio of the horizontal in-situ stress to the vertical in-situ stress), the in-situ stress in the coal seam can promote the propagation of vertical cracks but inhibit the propagation of horizontal cracks. When λ = 0.5 and 1, the in-situ stress inhibits the propagation of both horizontal and vertical cracks

Study on the Stress Field and Crack Propagation of Coal Mass Induced by High-Pressure Air Blasting

High-pressure air blasting (HPAB) is one type of physical blasting technique that enhances the extraction rate of coalbed methane by impacting the coal mass with high-pressure gas to create cracks within it. First, based on the physical and mechanical parameters of the simulated coal rock mass, the RHT constitutive model of the coal rock mass was established, and its parameters were determined. Then, the laws of crack propagation and stress wave decay in coal induced by high-pressure air blasting were revealed by comparing the effect with that of equivalent explosive blasting. Next, the HPAB experiment was simulated to explore the coal crack propagation law under in-situ stress conditions. Finally, the HPAB experiment was carried out and the results of this experiment were compared with the numerical simulation results. The results indicate that the crack propagation induced by high-pressure air blasting is considered as two major stages, i.e., the crack initiation and crack propagation stage induced by the stress wave and the crack stable propagation stage induced by the duration high-pressure gas. In the case of equal energy, the peak stress wave of high-pressure gas is smaller, decays more slowly and has a longer action time, compared to explosive blasting. Therefore, the number of initial random cracks in coal mass induced by high-pressure air blasting is less, and the range of crack propagation induced by high-pressure air blasting is larger. When λ = 0 (λ is the ratio of the horizontal in-situ stress to the vertical in-situ stress), the in-situ stress in the coal seam can promote the propagation of vertical cracks but inhibit the propagation of horizontal cracks. When λ = 0.5 and 1, the in-situ stress inhibits the propagation of both horizontal and vertical cracks

The impact of over-maturation on the sensory and nutritional quality of Gouqi (Chinese wolfberry) wine

This study compared the nutritional quality and sensory attributes of wine made from dried Gouqi berries that were mature (NDG), mildly over-matured (MDG) and severely over-matured (SDG). Whilst these wines had the similar physicochemical properties, the MDG wine possessed higher polysaccharide levels, whereas the highest total flavonoids were found in the NDG wine. A slight difference in the amino acid composition was observed in these wines, whereas they exhibited the same biogenic amines composition. The MDG and SDG wines exhibited weaker fruity, floral and caramel aromas compared with the NDG wine. However, these wines showed similar chemical and fatty aromas. Sensory evaluation revealed that these wines could be distinguished by panelists, and the NDG wine was preferred by most tasters, followed by the MDG and SDG wines. These results suggest that the Gouqi wine made from mature berries exhibits the best nutritional and organoleptic quality. However, the over-matured and severely over-matured berries could also be useful for Gouqi berry wine production but with different nutritional and sensory properties. Copyright (c) 2017 The Institute of Brewing & Distillin

Experimental Study on Damage Fracture Law of Coal from Solid-Propellant Blasting

The low permeability of coal seams has always been the main bottleneck restricting coalbed methane drainage. In this paper, a coal seam anti-reflection technology with solid-propellant blasting was proposed, and the composition and proportion of the solid propellants were determined based on the principle of oxygen balance. The authors designed a solid-propellant blasting damage fracture experiment of simulation coal, tested the impact pressure on a blast hole wall, measured the ultrasonic wave velocity, explosive strain and crack propagation velocity, and then revealed the blasting damage fracture process and mechanism of coal based on the experimental results and damage fracture mechanics theory. The history curve of impact pressure time can be divided into three processes including the slow pressurization process, dramatic increase process, and nonlinear pressure relief process. The pressure distribution along the whole blasting hole was uneven, and the peak pressure was relatively small, but the pressure action time was long. The damage and fracture process of coal solid-propellant blasting can be divided into two stages including the rapid damage fracture development stage and the stable slow damage fracture development stage. Firstly, the explosion stress wave produced and rapidly accelerated the radial cracks extension; secondly, the cracks slowly expanded over a large area by the combined effects of the high-pressure gases, the gas, and the original rock stress

Experimental Study on Damage Fracture Law of Coal from Solid-Propellant Blasting

The low permeability of coal seams has always been the main bottleneck restricting coalbed methane drainage. In this paper, a coal seam anti-reflection technology with solid-propellant blasting was proposed, and the composition and proportion of the solid propellants were determined based on the principle of oxygen balance. The authors designed a solid-propellant blasting damage fracture experiment of simulation coal, tested the impact pressure on a blast hole wall, measured the ultrasonic wave velocity, explosive strain and crack propagation velocity, and then revealed the blasting damage fracture process and mechanism of coal based on the experimental results and damage fracture mechanics theory. The history curve of impact pressure time can be divided into three processes including the slow pressurization process, dramatic increase process, and nonlinear pressure relief process. The pressure distribution along the whole blasting hole was uneven, and the peak pressure was relatively small, but the pressure action time was long. The damage and fracture process of coal solid-propellant blasting can be divided into two stages including the rapid damage fracture development stage and the stable slow damage fracture development stage. Firstly, the explosion stress wave produced and rapidly accelerated the radial cracks extension; secondly, the cracks slowly expanded over a large area by the combined effects of the high-pressure gases, the gas, and the original rock stress

Systematical Investigation of Flicker Noise in 14 nm FinFET Devices towards Stochastic Computing Application

Stochastic computing (SC) is widely known for its high error tolerance and efficient computing ability of complex functions with remarkably simple logic gates. The noise of electronic devices is widely used to be the entropy source due to its randomness. Compared with thermal noise and random telegraph noise (RTN), flicker noise is favored by researchers because of its high noise density. Meanwhile, unlike using RRAM, PCRAM and other emerging memory devices as the entropy source, using logic devices does not require any additional process steps, which is significant for industrialization. In this work, we systematically and statistically studied the 1/f noise characteristics of 14 nm FinFET, and found that miniaturizing the channel area of the device or lowering the ambient temperature can effectively increase the 1/f noise density of the device. This is of great importance to improve the accuracy of the SC system and simplify the complexity of the stochastic number generator (SNG) circuit. At the same time, these rules of 1/f noise characteristics in FinFET devices can provide good guidance for our device selection in circuit design

Biodegradable and Reusable Cellulose-Based Nanofiber Membrane Preparation for Mask Filter by Electrospinning

Environmentally friendly face masks with high filtration efficiency are in urgent need to fight against the COVID-19 pandemic, as well as other airborne viruses, bacteria and particulate matters. In this study, coaxial electrospinning was employed to fabricate a lithium chloride enhanced cellulose acetate/thermoplastic polyurethanes (CA/TPU-LiCl) face mask nanofiber filtration membrane, which was biodegradable and reusable. The analysis results show that the CA/TPU-LiCl membrane had an excellent filtration performance: when the filtration efficiency reached 99.8%, the pressure drop was only 52 Pa. The membrane also had an outstanding reusability. The filtration performance maintained at 98.2% after 10 test cycles, and an alcohol immersion disinfection treatment showed no effect on its filtration performance. In summary, the CA/TPU-LiCl nanofiber membrane made in this work is a promising biodegradable and reusable filtration material with a wide range of potential applications, including high-performance face mask