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Effects of H_2/CO/CH_4 syngas composition variation on the NO_x and CO emission characteristics in a partially-premixed gas turbine combustor

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Science China(Technological Sciences) 2016年第12期59卷 1804-1813页

作者： Lee Min Chul department of safety Engineering College of EngineeringFire Disaster Prevention Research CenterIncheon National University

This paper reports the effects of variations in the fuel composition of H_2/CO/CH_4 syngas on the characteristics of NO_x and CO emissions in a partially-premixed gas turbine combustor. Combustion tests were conducted on a full range of fuel compositions by varying each component gas from 0% to 100% at heat inputs of 40 and 50 k Wth. Flame temperature, combustor liner temperature, ignition delay time, and flame structure were investigated computationally and experimentally to judge whether they are significant indicators of NO_x and CO formation. The characteristics of and reasons for NO_x and CO emissions were investigated by analyzing the emission mechanisms and relationships among fuel property, equivalence ratio, flame temperature, liner temperature, flame shape. The flame structures were investigated using the following flame visualization methods:(1) time-averaged OH* chemiluminescence and its Abel-deconvolution;(2) direct photography; and(3) instantaneous OH-PLIF. The flame structures were greatly changed by the fuel composition and heat input, and they were subjected to key affecting parameters of the temperatures of the flames and the liners. NO_x and CO emissions also largely varied according to fuel composition and heat input, showing neither linearly nor exponentially clear proportional trends toward the syngas compositions because of the singular conditions. For example, only the 100% CO flame at low load emitted lots of CO, whereas complete combustion was observed in other cases. However, the qualitative observations showed that the root causes of NO_x emission behaviors were flame temperature and flame structure, which were directly related to the residence time in the flame. Various sets of practical test results were obtained, and these results could contribute to the optimal selection of the fuel-feeding condition when fuel is changed from natural gas to syngas in order to minimize NO_x and CO emissions with stable combustion.

关键词： gas turbine combustor NO_x and CO emission synthetic gas OH* chemiluminescence planar laser induced fluorescence

Combustion Characteristics of Solid Refuse Fuels from Different Waste Sources

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Journal of Renewable Materials 2020年第7期8卷 789-799页

作者： Jong Seong Chae Seok Wan Kim Tae In Ohm department of Civil and Environmental Engineering Hanbat National UniversityDaejeon34158Korea department of fire and Environmental safety Daegu Haany UniversityDaegu38610Korea

In the production(as co-fuel or alone)of solid refuse fuel(SRF),knowledge about the characteristics of the raw materials is required for an ecofriendly and effective combustion *** are commonly produced by drying combustible waste and removing incombustible matter,resulting in a higher combustibility as compared to the original ***,the characteristics of SRFs may highly vary depending on where and from which materials they were ***,we investigated the characteristics of various SRFs using thermogravimetric analysis(TGA).As a TGA sample is commonly small,on the scale of milligrams,and,unlike homogeneous fuels,SRFs are heterogeneous,individual SRF samples analysed with this method may not represent the bulk material,and sample properties may vary significantly between ***,we further performed combustion experiments using a small-scale combustor and sample sizes from 1 to 10 *** optimise SRF combustor design and determine the SRF characteristics,proximate,elemental,heating value,TG,and differential thermogravimetric analyses were conducted,and weight losses and gas concentrations at different temperatures were measured upon *** lower heating values of the three analysed SRFs were 20,976,16,873,and 19,762 kJ/kg,and their Cl contents were 0.89,0.95,and 1.27 wt.%(legal criterion[Cl]<2.0 wt.%).TGA and small combustor experiments showed that complete weight loss was achieved below 500°***,CO was detected until 620°C.

关键词： Solid refuse fuel small-scale combustor thermogravimetric analysis waste gas concentration

Design and Performance Simulation of a Novel Liquid CO_2 Cycle Refrigeration System for Heat Hazard Control in Coal Mines

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Journal of Thermal Science 2019年第3期28卷 585-595页

作者： ZHAI Xiaowei XU Yu YU Zhijin College of safety Science and Engineering Xi'an University of Science and Technology Shaanxi Key Laboratory of Prevention and Control of Coal fire

LCO_2(liquid CO_2) can absorb heat and release latent heat via phase transition, which can provide considerable cooling energy and effectively solve the problem of thermal damage in deep coal mining processes. A LCO_2 cycle refrigeration system is designed to continuously cool down the working face in a mine, and CO_2 is cyclically utilized. Additionally, LCO_2 is used not only as a cold source but also to prevent spontaneous combustion of coal in the gob. COMSOL Multiphysics simulation software is used to characterize the thermal performance of the heat exchange system, where the heat transfers between the CO_2 and the airflow. For a LCO_2 consumption of 13.54 m^3/h, the temperature of the airflow in the tunnel decreases by 7.72°C, and the cooling volume of the system reaches 142.99 kW/h; the cooling volume provides a latent heat release of 46.68 k W/h. The main influencing factors of the refrigeration system, such as ventilation flux, LCO_2 flow, LCO_2 temperature and initial tunnel temperature, are also analyzed quantitatively through the software. The temperature of the steady airflow in the tunnel is proportional to the square of the local fan ventilation flux, and it decreases linearly with an increase in the LCO_2 flow but increases with both the temperature of the LCO_2 and the initial temperature in the tunnel. When the temperature difference between the LCO_2 and wind increases, the heat exchange between the CO_2 and wind intensifies, and the cooling volume increases.

关键词： LCO2 refrigeration working face cooling numerical simulation heat exchange

Insights into Pyrolysis of Nano-Polystyrene Particles: Thermochemical Behaviors and Kinetics Analysis

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Journal of Thermal Science 2019年第4期28卷 763-771页

作者： DING Li ZHAO Jianping PAN Yong GUAN Jin JIANG Juncheng WANG Qingsheng College of Mechanical and Power Engineering Nanjing Tech UniversityNanjing 211816China College of safety Science and Engineering Nanjing Tech UniversityNanjing 211816China department of fire Protection and safety Oklahoma State UniversityStillwater 74078USA

The thermal degradation kinetics of nano-polystyrene particles with diameters of 60,90,160,and 225 nm were investigated in nitrogen atmosphere using thermogravimetric analysis(TGA).Various kinetic models were employed to determine the thermal degradation mechanism and ***-polystyrene particles have relatively lower thermal stability when compared to *** differential thermo–gravimetric(DTG)data and apparent activation energies indicate that the thermal degradation of nano-polystyrene particles at 60 nm is a two-step reaction process where the second step plays a dominant role,while nano-polystyrene particles with diameter greater than 60 nm exhibit single-step *** to most micro/macro polystyrene particles,DTG peaks of nano-polystyrene particles shift towards higher temperatures with increasing heating *** degradation of nano-polystyrene particles under nitrogen atmosphere follows the first-order reaction ***,the apparent activation energies increase(162-181 kJ·mol–1)with the increase of particle sizes(60-225 nm).This study could provide some insights into pyrolysis of nano-polystyrene particles and a safer process of manufacturing,storage and handling of nano-polystyrene particles.

关键词： nano-polystyrene thermal decomposition kinetics mechanism

Required width of exit to avoid the faster-is-slower effect in highly competitive evacuation

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Chinese Physics B 2017年第8期26卷 219-224页

作者：张玉春马剑司有亮冉桐吴凡雨王国元林鹏 department of fire safety Engineering Faculty of Geosciences and Environmental EngineeringSouthwest Jiaotong UniversityChengdu 610031China School of Transportation and Logistics Southwest Jiaotong UniversityChengdu 610031China

A group of competitive people escaping through an exit could lead to the formation of a deadlock, which significantly increases the evacuation time. Such a phenomenon is called the faster-is-slower effect（FIS） and it has been experimentally verified in different systems of particles flowing through an opening. In this paper, the numerical simulation based on discrete element method（DEM） is adopted to study a group of highly competitive people through an exit of varying widths. The FIS effect is observed for a narrow exit whilst it is not observed for the exit wide enough to accommodate two people through it side-by-side. Experimental validation of such a phenomenon with humans is difficult due to ethical issues. The mouse is a kind of self-driven and soft-body creature and it exhibits selfish behaviour under stressed *** flowing through an opening in different systems, such as pedestrian flow, animal flow, silo flow, etc. have similar characteristics. Therefore, experimental study is conducted by driving mice to escape through an exit of different widths at varying levels of stimulus. The escape time through a narrow exit（i.e., 2 cm） increases obviously with the increase of stimulus level but it is quite opposite to a wider exit（i.e., 4 cm）. The FIS effect is avoided for an exit wide enough to accommodate two mice passing through it side-by-side. The study illustrates that FIF effect could be effectively prevented for an exit when its width is twice the size of particles.

关键词： faster-is-slower effect DEM exit width highly competitive evacuation

A numerical study of contact force in competitive evacuation

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Chinese Physics B 2017年第10期26卷 295-301页

作者：林鹏马剑司有亮吴凡雨王国元王建宇 department of fire safety Engineering Faculty of Geosciences and Environmental Engineering Southwest Jiaotong University Chengdu 610031 China School of Transportation and Logistics Southwest Jiaotong University Chengdu 610031 China

Crowd force by the pushing or crushing of people has resulted in a number of accidents in recent decades. The aftermath investigations have shown that the physical interaction of a highly competitive crowd could produce dangerous pressure up to 4500 N/m, which leads to compressive asphyxia or even death. In this paper, a numerical model based on discrete element method （DEM） as referenced from granular flow was proposed to model the evacuation process of a group of highly competitive people, in which the movement of people follows Newton＇s second law and the body deformation due to compression follows Hertz contact model. The study shows that the clogs occur periodically and flow rate fluctuates greatly if all people strive to pass through a narrow exit at high enough desired velocity. Two types of contact forces acting on people are studied. The first one, i.e., vector contact force, accounts for the movement of the people following Newton＇s second law. The second one, i.e., scale contact force, accounts for the physical deformation of the human body following the contact law. Simulation shows that the forces chain in crowd flow is turbulent and fragile. A few narrow zones with intense forces are observed in the force field, which is similar to the strain localization observed in granular flow. The force acting on a person could be as high as 4500 N due to force localization, which may be the root cause of compressive asphyxia of people in many crowd incidents.

关键词： crowd flow discrete element method (DEM) contact force force localization

Influence of opening ratios and directions of windows on natural smoke exhaust effect in atrium buildings

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Building Simulation 2022年第4期15卷 571-582页

作者： Peng Wang Xiankun Wang Keheng Chen Hongyu Wei Qianhang Feng Yuanyi Xie Xuechao He Yanqiu Chen department of fire Protection Engineering Southwest Jiaotong UniversityChengduSichuan 610031China Sichuan fire Research Institute of MEM China

In this paper,the influence of different opening ratios and different opening directions of the windows on the natural smoke exhaust was studied through a series of real fire experiments and simulation *** the open area of the window could effectively improve the overall smoke exhaust *** the top windows were open and the opening ratio increased from 19.2%to 24.3%,the optical density was decreased by 12.4%.The average smoke exhaust rate per unit area of the window did not change *** the area of the natural smoke exhaust window could effectively increase the smoke exhaust rate and improve the overall effect of smoke *** the top windows were open,the temperature rise on the top floor was 30.8%-47.5%lower while the visibility was 16.8%-21.9%higher than that when the side windows were open.

关键词： natural smoke exhaust atrium opening ratio opening direction

Maximizing biomass utilization: An integrated strategy for coproducing multiple chemicals

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Journal of Energy Chemistry 2025年第1期100卷 180-191页

作者： Byeongchan Ahn Sua Jo Jonggeol Na J.Jay Liu Young-Ju Kim Wangyun Won department of Chemical and Biological Engineering Korea University department of Chemical Engineering (Integrated process) Kyung Hee University department of Chemical Engineering and Materials Science Ewha Womans University department of Chemical Engineering Pukyong National University Resources Engineering Plant Research department Korea Institute of Geoscience and Mineral Resources

Lignocellulosic biomass is one of the viable solutions to alleviate the global warming. However, the limited utilization of biomass majorly focused on cellulose and hemicellulose restricts the economic and environmental feasibilities. To cope with this issue, we proposed an integrated process of co-producing 1,6-hexanediol（1,6-HDO） with tetrahydrofuran and adipic acid from biomass, referred to as Strategy A. To compare the impacts of lignin upgrading and feedstock, Strategy B, which co-produces tetrahydrofuran alone, and Strategy C, which is the traditional route to produce 1,6-HDO from fossil fuels, were used. Heat networks are also designed to reduce operating costs and indirect carbon emissions due to energy consumption, saving 87% and 83% of the heat and cooling requirements, respectively, in Strategy A. The market competitiveness of Strategy A was evaluated by determining the minimum selling price through techno-economic analysis, and sustainability was thoroughly investigated by quantifying the environmental impacts through both midpoint and endpoint life-cycle assessments（LCAs）.Strategy A was found to be the most favorable both economically（USRDSCHARDOLLAR3,402/ton） and environmentally（-26.9 kg CO2eq.）. This indicates that lignin valorization is not only economically but also environmentally preferred. Finally, changes in economic and environmental feasibilities depending on economic, process, and environmental parameters were investigated using sensitivity and uncertainty analyses. The results of these analyses provide valuable insight into bio-based chemical production.

关键词： Biorefinery Carbon mitigation Climate change Global warming Lignin utilization Bioeconomy

A state-of-the-art review of the development of self-healing concrete for resilient infrastructure

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Frontiers of Structural and Civil Engineering 2024年第2期18卷 151-169页

作者： Dong LU Xi JIANG Yao ZHANG Shaowei ZHANG Guoyang LU Zhen LENG department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityHong Kong 999077China Laboratory of fire safety School of Safety Engineering and Emergency ManagementShijiazhuang Tiedao UniversityShijiazhuang 050043China department of Architecture and Civil Engineering City University of Hong KongHong Kong 999077China

The brittleness of cement composites makes cracks almost inevitable,producing a serious limitation on the lifespan,resilience,and safety of concrete *** address this brittleness,self-healing concrete has been developed for regaining its mechanical and durability properties after becoming cracked,thereby promising sustainable development of concrete *** paper provides a comprehensive review of the latest developments in self-healing *** begins by summarizing the methods used to evaluate the self-healing efficiency of ***,it compares strategies for achieving healing *** then discusses the typical approaches for developing self-healing ***,critical insights are proposed to guide future studies on the development of novel self-healing *** review will be useful for researchers and practitioners interested in the field of self-healing concrete and its potential to improve the durability,resilience,and safety of concrete infrastructure.

关键词： resilient infrastructure sustainable concrete self-healing cracks