scholarly journals Effect of Solid Waste-Petroleum Coke Residue on the Hydration Reaction and Property of Concrete

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1216 ◽  
Author(s):  
Liang Wang ◽  
Hongzhu Quan ◽  
Qiuyi Li
Keyword(s):  
Petroleum Coke ◽  
Circulating Fluidized Bed ◽  
Strength Loss ◽  
Economic Benefits ◽  
Coke Residue ◽  
Mineral Admixtures ◽  
Cement Clinker ◽  
Utilization Rate ◽  
Hydration Reaction ◽  
Hydration Mechanism

Taking advantage of the desulfurization petroleum coke residue obtained from circulating fluidized bed boiler technology to replace a part of cement clinker and prepare the concrete can not only reduce the production of cement clinker and related CO2 emissions, but can also improve the utilization rate and utilization level of petroleum coke waste, which has good environmental and economic benefits. In this study, through the comprehensive analysis of a compressive strength test, X-ray diffraction test, and Cl− penetration resistance test, the hydration mechanism of desulfurized petroleum coke residue in concrete is revealed, and the optimum replacement ratios of single-added petroleum coke residue, multi-added petroleum coke residue, and mineral admixtures in concrete are evaluated and proposed. The results showed that mixing the 10% petroleum coke residue and 40% blast furnace slag would be most appropriate to replace the cement in concrete, thus the effective utilization of mineral admixtures and coke residue in concrete without strength loss could be realized.

scholarly journals Experiment and Analysis of Wedge Cutting Angle on Cutting Effect

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Deqiang Yang ◽  
Xuguang Wang ◽  
Yinjun Wang ◽  
Huaming An ◽  
Zhen Lei
Keyword(s):  
Construction Cost ◽  
Economic Benefits ◽  
Tunneling Rate ◽  
Vibration Velocity ◽  
Utilization Rate ◽  
Engineering Practice ◽  
Blasting Vibration ◽  
Cutting Depth ◽  
Vertical Side ◽  
Cutting Angle

In the process of tunnel excavation, large charge wedge cutting blasting is widely used to improve the effect of cut blasting and speed up the excavation rate, which is tantamount to increasing the construction cost. In order to save economic cost and improve cutting blasting effect, wedge cutting models with five different cutting angles were experimented and studied by using concrete materials on the basis of similarity theory analysis. The relationships among cutting depth, blasting volume, blasting fragment, and cutting angle are studied and deduced by the dimensional analysis method. The polynomial fitting of cutting depth, blasting volume, blasting fragment, and cutting angle is carried out according to the experimental data, and the corresponding fitting formula is obtained. The optimum cutting depth, hole utilization rate, blasting volume, and blasting fragment were obtained when the wedge cutting angle was 67° under the same charge. The values were 1.665 × 10−1 m, 92.5%, 8.390 × 10−3 m3, and 49.07 mm, respectively. With the use of TC4850N type blasting vibration meter, the blasting vibrations on the wedge in four directions are tested and analyzed. The results show that when wedge cutting inclination is 65 degrees, the peak vibration velocity is the minimum and the vibration intensity of the wedge cutting inclined side is generally smaller than that of the vertical side. Considering the cutting depth, blasting volume, blasting fragment, blasting vibration hazard, drilling error, tunneling construction cost, and other factors, the 65°∼69° wedge cutting blasting in engineering practice can improve the blasting tunneling rate and increase economic benefits. The experimental results show that the blasting tunneling rate is increased and the economic benefit is increased with the minimum construction tunneling cost, which has certain engineering significance.

scholarly journals Development on Thermochemical Energy Storage Based on CaO-Based Materials: A Review

2018 ◽  
Vol 10 (8) ◽  
pp. 2660 ◽  
Author(s):  
Yi Yuan ◽  
Yingjie Li ◽  
Jianli Zhao
Keyword(s):  
Renewable Energy ◽  
Energy Storage ◽  
Energy Density ◽  
Circulating Fluidized Bed ◽  
High Energy ◽  
High Energy Density ◽  
Hydration Reaction ◽  
Initial Sample ◽  
Storage Performance ◽  
Low Activity

The intermittent and inconsistent nature of some renewable energy, such as solar and wind, means the corresponding plants are unable to operate continuously. Thermochemical energy storage (TES) is an essential way to solve this problem. Due to the advantages of cheap price, high energy density, and ease to scaling, CaO-based material is thought as one of the most promising storage mediums for TES. In this paper, TES based on various cycles, such as CaO/CaCO3 cycles, CaO/Ca(OH)2 cycles, and coupling of CaO/Ca(OH)2 and CaO/CaCO3 cycles, were reviewed. The energy storage performances of CaO-based materials, as well as the modification approaches to improve their performance, were critically reviewed. The natural CaO-based materials for CaO/Ca(OH)2 TES experienced the multiple hydration/dehydration cycles tend to suffer from severe sintering which leads to the low activity and structural stability. It is found that higher dehydration temperature, lower initial sample temperature of the hydration reaction, higher vapor pressure in the hydration reactor, and the use of circulating fluidized bed (CFB) reactors all can improve the energy storage performance of CaO-based materials. In addition, the energy storage performance of CaO-based materials for CaO/Ca(OH)2 TES can be effectively improved by the various modification methods. The additions of Al2O3, Na2Si3O7, and nanoparticles of nano-SiO2 can improve the structural stabilities of CaO-based materials, while the addition of LiOH can improve the reactivities of CaO-based materials. This paper is devoted to a critical review on the development on thermochemical energy storage based on CaO-based materials in the recent years.

scholarly journals Study on the path of Integration use of Land Resource elements under the background of Rural Revitalization

2021 ◽  
Vol 236 ◽  
pp. 01040
Author(s):  
Hong Tang ◽  
Changpin Ji ◽  
Yan Zhao
Keyword(s):  
Rural Areas ◽  
Rapid Development ◽  
Economic Benefits ◽  
Utilization Rate ◽  
Circulation System ◽  
Land Resource ◽  
Resource Integration ◽  
Land Utilization ◽  
Negative Effects ◽  
Rural Economic Development

At present, with the rapid development of urban-rural integration, the problems of land fragmentation in rural areas, such as low land use rate, poor economic benefits, many production conflicts and disputes, land distribution difficulties and other negative effects, continue to appear, and the rural economic development is very severe. Based on this, this paper mainly studies the path of land resource integration, studies the reform of land system in various aspects, such as land circulation system, homestead reform, land acquisition system and other specific systems, and studies the specific path of land resource integration, so as to promote the land utilization rate, promote the rapid development of population industry and its development The increase of farmers' income.

Retrofitting 25T/h Pulverized Coal-Fired Boiler Into 35T/h Circulating Fluidized Bed Boiler for Burning Mixture of Coal and Bagasse

2005 ◽  
Author(s):  
Han-Ping Chen ◽  
Xian-Hua Wang ◽  
Shi-Hong Zhang ◽  
De-Chang Liu ◽  
Yu-Hua Lai ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Combustion Efficiency ◽  
Economic Benefits ◽  
Pulverized Coal ◽  
Industrial Wastes ◽  
Pollutant Emission ◽  
Fluidized Bed Combustion ◽  
Circulating Fluidized Bed Boiler ◽  
Combustion Technology

In China, there are a large number of pulverized coal-fired industrial boilers, whose steam capacities are usually relatively small. These boilers can burn only high-grade coal and have low combustion efficiency. Furthermore, the combustion emissions, such as SO2 and NOx, pollute the environment severely. Therefore it is very important and urgent to adopt economically efficient and environmentally friendly technologies to retrofit these boilers. At the same time, there are many industrial wastes, such as bagasse, wood waste, rubbish, petroleum coke and so on, need burning disposal in China. Fluidized bed combustion technology is a kind of clear combustion technology, which has many advantages, such as excellence fuel flexibility, high combustion efficiency, low pollutant emission and good turndown capability etc. So, adopting fluidized bed combustion technology, retrofitting pulverized coal-fired boiler into fluidized bed boiler can realize pure burning various wastes or co-firing with coal, which should have great economic benefits and social benefits. And the application prospect of the method is also extensive. The State Key Laboratory of Coal Combustion has successfully retrofitted a 25t/h pulverized coal-fired boiler into circulating fluidized bed boiler with in-bed tubes and downward exhaust cyclone. The retrofitted boiler can burn mixture of coal and bagasse and the steam capacity reaches 35t/h. This paper presents the retrofitting measures and the operation status of the boiler after retrofitting.

scholarly journals Research and design of grid connection and waste heat utilization of marine generating units

2020 ◽  
Vol 165 ◽  
pp. 06003
Author(s):  
Anning Yi ◽  
Hongtao Guo
Keyword(s):  
Power Generation ◽  
Service Life ◽  
Temperature Difference ◽  
Electromagnetic Interference ◽  
Frequency Conversion ◽  
Waste Heat ◽  
Economic Benefits ◽  
Energy Output ◽  
Utilization Rate ◽  
Energy Unit

This work is based on the use of waste heat from the temperature difference semiconductor heat exchanger, which can effectively use the waste heat in the exhaust gas, and convert it into electrical energy output through the temperature difference semiconductor material, which can increase engine efficiency and reduce energy consumption; at the same time, it can reduce engine noise and vibration. Extended service life. Due to the strong electromagnetic interference and severe vibration of the generator, there are few remote control devices on the market for the generator. This project uses a 2.4G wireless communication module to control the frequency conversion and speed regulation of the generator. In order to save manpower, start remotely, stop as soon as possible, monitor the operating status of the waste heat temperature difference power generation, reasonably replace the power, start quickly, and reach the electromechanical Integrated product. The realization of intelligent frequency conversion technology can adjust the engine speed according to different electrical appliances, adapt to external loads, realize automatic voltage adjustment, and save fuel consumption. The grid-connected system solves the frequency and phase problems of generators of different models, generations, and manufacturers in parallel, and realizes the re-mixing of old generators, which greatly improves the service life of engines and the best power generation supply, and reduces power generation systems and storage. The configuration cost of the energy unit improves the comprehensive utilization rate of the equipment, has a higher working efficiency, has good economic benefits, and can achieve the purpose of energy saving and emission reduction.

OP42 Cost-Benefit Of Computed Tomography In Secondary Hospitals In China

2017 ◽  
Vol 33 (S1) ◽  
pp. 19-19
Author(s):  
Hui Sun ◽  
Yingyao Chen ◽  
Jian Ming ◽  
Yan Wei ◽  
Luyang He
Keyword(s):  
Computed Tomography ◽  
Detection Rate ◽  
Cost Benefit ◽  
Economic Benefits ◽  
Cost Recovery ◽  
Utilization Rate ◽  
Effective Utilization ◽  
Equipment Utilization ◽  
The Cost ◽  
Benefit Cost

INTRODUCTION:With the promotion of a tiered medical service system, secondary hospitals will play a more important role in the future. This study aims to explore the cost-benefit of computed tomography (CT) in secondary hospitals in China, with a view to providing information for overall economic management in hospitals as well as for regional planning of medical equipment in different areas.METHODS:Fifty-eight secondary hospitals from six provinces located in the eastern, central, and western regions of China were selected as the study sample. Questionnaires were used to collect information on the cost structure, efficiency, and benefits of CT in the secondary hospitals in the past 5 years. Cost analysis was conducted from the perspective of the hospitals, which mainly referred to direct fixed costs and variable costs. We analyzed the investment recovery years a, cost recovery rate b, and benefit-cost ratio to evaluate the economic benefits of CT. We also analyzed the technological benefits of CT based on its effective utilization rate c and positive detection rate. a:Investment recovery years = total original investment / (annual net income + annual depreciation expense)b:Cost recovery rate = average income per check / average cost per checkc:Effective utilization rate = single equipment utilization rate * positive detection rate(Single equipment utilization rate = actual working time / rated working time)RESULTS:Depreciation costs (36.3 percent) were the largest proportion of all costs over the 5-year period, followed by material costs (22.2 percent), maintenance costs (18.2 percent), labor costs (17.1 percent), and electricity consumption (1.2 percent). The investment recovery periods of CT in the eastern, central, and western regions were 2.5, 2.8, and 3.1 years, respectively; the cost recovery rates were 186.5 percent, 172.0 percent, and 174.1 percent, respectively; the benefit-cost ratios were 1.9, 1.7, and 1.7, respectively; the effective utilization rates were 46.1 percent, 58.3 percent, and 71.2 percent, respectively; and the positive detection rates were 52.3 percent, 60.5 percent, and 73.3 percent, respectively.CONCLUSIONS:The current study indicates that the cost-benefit of CT is good in secondary hospitals, especially in terms of economic benefits. But to achieve greater technological benefits in all three regions, more appropriate utilization of CT is needed.

scholarly journals Mechanical Properties and Microscopic Mechanism of Coral Sand-Cement Mortar

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Luoxin Wang ◽  
Junshuai Mei ◽  
Jing Wu ◽  
Xingyang He ◽  
Hainan Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cement Mortar ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Hardened Cement ◽  
Hydration Reaction ◽  
Microscopic Mechanism ◽  
X Ray ◽  
Volume Stability ◽  
Coral Sand

The workability and mechanical performance of coral sand-cement mortar (coral mortar, for short) and the modification effects of mineral admixtures on the coral mortar were studied in this paper. The results showed that the strength of coral mortar was lower than that of standard mortar, but the strength of coral mortar was improved by compositing with the mineral admixture, which can be attributed to the improvement of the microstructure and interface transition area. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to explore the microscopic mechanism involved in the mechanical properties, volume stability, and hydration of mortar. The analyses revealed that the internal curing effect of coral sand improved the mechanical properties of mortar and its ability to resist shrinkage. The uneven surface of coral sand formed a meshing state of close combination with the hardened cement mortar, which helped to improve the volume stability of mortar. The Ca2+ and Mg2+ ions from coral sand participated in the hydration reaction of cement, which contributed to generating more hydration products. Moreover, the microaggregate filling and pozzolanic effects of fly ash and slag improved the mechanical properties of coral mortar and resistance to chloride ion diffusion.

scholarly journals Experimental Study on the Concrete with Compound Admixture of Iron Tailings and Slag Powder under Low Cement Clinker System

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Ruidong Wu ◽  
Juanhong Liu
Keyword(s):  
Diffusion Coefficient ◽  
Mineral Admixture ◽  
Chloride Diffusion ◽  
Cement Clinker ◽  
Hydration Reaction ◽  
Chloride Diffusion Coefficient ◽  
Carbonation Depth ◽  
Mixture Ratio ◽  
Slag Powder ◽  
Powder Content

In order to study the performance of concrete with compound admixture of iron tailings and slag powder under low cement clinker system, the mixture ratio of different iron tailings powder and slag powder was designed to prepare C30 and C50 concrete. The workability, strength, carbonation depth, chloride diffusion coefficient, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) of concrete were measured, respectively. The test results show that iron tailings powder is beneficial to improve the workability, and the strength of concrete decreases with the increase of iron tailings powder content, while the carbonation depth and chloride diffusion coefficient increase with the increase of iron tailings powder content. Under low cement clinker system, the iron tailings powder should not be used alone (below 70% of mineral admixture). When the ratio of iron tailings to slag powder is 1 : 1, the strength, carbonation depth, chloride ion permeation coefficient, and the microstructure of concrete are roughly the same to that of concrete with single slag powder. So, the iron tailings powder can replace S95 grade slag powder in the same quantity. Iron tailings powder does not take part in hydration reaction, but it can improve particle gradation, reach close accumulation, and increase the quantity of central grains.

scholarly journals Effects of Expansive Agents on the Early Hydration Kinetics of Cementitious Binders

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1900 ◽  
Author(s):  
Miao Miao ◽  
Qingyang Liu ◽  
Jian Zhou ◽  
Jingjing Feng
Keyword(s):  
Fly Ash ◽  
Hydration Heat ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Hydration Reaction ◽  
Hydration Kinetics ◽  
Early Hydration ◽  
Expansive Agent ◽  
Mechanical Performances ◽  
Kinetics Of

The addition of expansive agents could overcome the main disadvantages of raw concrete including high brittleness and low tensile strength. Few studies have investigated the early hydration kinetics of expansive cementitious binders, though the findings from the early hydration kinetics are helpful for understanding their technical performances. In this study, mixtures of 3CaO•3Al2O3•CaSO4 and CaSO4 (i.e., ZY-type™ expansive agent) with different proportions of mineral admixtures (e.g., fly ash and slag) were added into cement pastes to investigate the early hydration kinetics mechanism of expansive cementitious binders. Early hydration heat evolution rate and cumulative hydration heat were measured by isothermal calorimeter. Kinetic parameters were estimated based on the Krstulovic–Dabic model and Knudsen equations. Mechanical performances of expansive cementitious binders were tested in order to evaluate if they met the basic requirements of shrinkage-compensating materials in technical use. The early hydration heat released from cementitious binders containing ZY-type™ expansive agent was much greater than that released by pure cement, supporting the idea that addition of the expansive agent would improve the reaction of cement. The early hydration kinetic rates were decreased due to the reactions of the mineral admixture (e.g., fly ash or slag) and the ZY-type™ expansive agent in the cement system. The hydration reaction of cementitious binders containing ZY-type™ expansive agent obeyed the Krstulovic–Dabic model well. Three processes are involved in the hydration reaction of cementitious binders containing ZY-type™ expansive agent. These are nucleation and crystal growth (NG), interactions at phase boundaries (I), and diffusion (D). The 14-day expansion rates of cementitious binders containing ZY-type™ expansive agent are in the range of 2.0 × 10−4 to 3.5 × 10−4, which could meet the basic requirements of anti-cracking performances in technical use according to Chinese industry standard JGJ/T 178-2009. This study could provide an insight into understanding the effects of expansive agents on the hydration and mechanical performances of cementitious binders.

The Activation of Steel Slag and its Application in Construction and Building Materials

2014 ◽  
Vol 884-885 ◽  
pp. 702-705 ◽  
Author(s):  
Lan Lan Li ◽  
Feng Qing Zhao ◽  
Shao Jie Liu
Keyword(s):  
Building Materials ◽  
Steel Slag ◽  
Concrete Block ◽  
Cement Clinker ◽  
Research Progress ◽  
Hydration Reaction ◽  
Crude Steel ◽  
Volume Stability ◽  
Industrial Solid Waste ◽  
Combined Use

Steel slag as the discharged residue during steelmaking process is a kind of industrial solid waste, accounting for about 15 to 20 percent of crude steel in production. Steel slag is mainly similar with cement clinker in mineral and chemical composition, and possesses potential hydration reaction activity. The properties of steel slag, the research progress of activation and volume stability were summarized in this paper. Several approaches of steel slag utilization in construction and building materials were introduced. The combined use of various activation methods and proper treatment will increase the volume of steel slag in autoclaved tailings bricks and aerated concrete block.

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