Journal of The Energy Institute最新文献_第9页

Study on the effect of Ni-modified biochar-based catalysts on the steam reforming process of biomass and plastics for hydrogen production

IF 5.6 2区工程技术 Q2 ENERGY & FUELS

Journal of The Energy Institute

Pub Date : 2024-12-21 DOI: 10.1016/j.joei.2024.101960

Hengyu He, Zhen Zhou, Hong Tian, Chenyang Sun, Yanni Xuan

As traditional fossil fuels are gradually depleting, finding green and renewable alternative energy sources has become increasingly important. The steam reforming of waste plastics and biomass mixtures for hydrogen production is regarded as a promising solution. Biomass (wheat straw) and Plastic (low-density polyethylene) were picked as the study's basic materials, water (H₂O) was employed as the gasification agent, and biochar (Wheat straw charcoal)-loaded nickel (Ni) was utilized as the catalyst. BET, XRD, FTIR, SEM, and ICP-OMS have been employed to examine the modified biochar's catalyst chemical makeup and structural characteristics. The impact of varying Ni loadings catalyst, catalytic reforming temperature, steam flow rate, and feedstock blending ratio on the process of steam reforming of biomass/plastics to hydrogen were investigated. The outcomes showed that the catalyst Ni/WB-C had functional groups that contained oxygen and a rich pore structure. The optimal experimental conditions for steam reforming of biomass/plastics to hydrogen were achieved at a Ni loading of 15 wt%, pyrolysis temperature of 600 °C, catalytic reforming temperature of 800 °C, steam flow rate of 0.2 g/min, and biomass/plastic ratio of 5:5. In accordance with the aforementioned condition, the total gas yield, the H₂ yield, and its percentage, and the H₂/CO ratio, were found to be 109.4 mmol/g, 77.5 mmol/g, 70.8 %, and 3.97. Therefore, this study provides an effective new approach to enhance H₂ production from steam reforming of waste plastics/biomass.

{"title":"Study on the effect of Ni-modified biochar-based catalysts on the steam reforming process of biomass and plastics for hydrogen production","authors":"Hengyu He, Zhen Zhou, Hong Tian, Chenyang Sun, Yanni Xuan","doi":"10.1016/j.joei.2024.101960","DOIUrl":"10.1016/j.joei.2024.101960","url":null,"abstract":"<div><div>As traditional fossil fuels are gradually depleting, finding green and renewable alternative energy sources has become increasingly important. The steam reforming of waste plastics and biomass mixtures for hydrogen production is regarded as a promising solution. Biomass (wheat straw) and Plastic (low-density polyethylene) were picked as the study's basic materials, water (H<sub>2</sub>O) was employed as the gasification agent, and biochar (Wheat straw charcoal)-loaded nickel (Ni) was utilized as the catalyst. BET, XRD, FTIR, SEM, and ICP-OMS have been employed to examine the modified biochar's catalyst chemical makeup and structural characteristics. The impact of varying Ni loadings catalyst, catalytic reforming temperature, steam flow rate, and feedstock blending ratio on the process of steam reforming of biomass/plastics to hydrogen were investigated. The outcomes showed that the catalyst Ni/WB-C had functional groups that contained oxygen and a rich pore structure. The optimal experimental conditions for steam reforming of biomass/plastics to hydrogen were achieved at a Ni loading of 15 wt%, pyrolysis temperature of 600 °C, catalytic reforming temperature of 800 °C, steam flow rate of 0.2 g/min, and biomass/plastic ratio of 5:5. In accordance with the aforementioned condition, the total gas yield, the H<sub>2</sub> yield, and its percentage, and the H<sub>2</sub>/CO ratio, were found to be 109.4 mmol/g, 77.5 mmol/g, 70.8 %, and 3.97. Therefore, this study provides an effective new approach to enhance H<sub>2</sub> production from steam reforming of waste plastics/biomass.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"119 ","pages":"Article 101960"},"PeriodicalIF":5.6,"publicationDate":"2024-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143135984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Experimental study on CH4/NH3 turbulent lifted flames with the variations in air coflow velocity and fuel nozzle diameter

IF 5.6 2区工程技术 Q2 ENERGY & FUELS

Journal of The Energy Institute

Pub Date : 2024-12-21 DOI: 10.1016/j.joei.2024.101939

Kousuo Fu , Neng Tao , Liqiao Jiang , Honghao Wu , Xing Li , Haolin Yang , Xiaohan Wang

Many environmental problems caused by the significant increase in carbon emissions are receiving widely attention, while developing ammonia-containing fuel combustion technology is an essential and feasible strategy. In this paper, an experimental study and theoretical analysis of CH₄/NH₃ jet flame in air coflow were carried out to investigate the effects of air coflow velocity and fuel nozzle diameter variations on the combustion characteristics of ammonia-blended conventional fuels. With the increase of ammonia concentration, the flame chemical luminosity of blended fuels gradually decreased, and the flame root transitioned from bright blue to dark orange. The nozzle diameter and air coflow velocity significantly affected whether the CH₄/NH₃ jet attached flame can develop into a lifted flame. Meanwhile, three trends and developmental stages of liftoff height with increasing jet velocity were identified for CH₄/NH₃ turbulent flame, which could be attributed to the ammonia concentration and the flow regime of fuel stream, respectively. The experimental results indicated that the blowoff limit and steady burning region decreased gradually with the increase of ammonia mixing ratio and air coflow velocity, which were positively correlated with the nozzle diameter. Based on the premixed flame model and large-scale mixing model, flammability limit range and relative dilution effect of the fuel mixture were found as important factors in predicting the liftoff height. The results indicated that the modified models could estimate the liftoff height better. In addition, the impact mechanism of air coflow velocity on the blowoff limit in two prediction models was discussed, and a more accurate prediction of the blowoff velocity was achieved by introducing the correction factor k.

{"title":"Experimental study on CH4/NH3 turbulent lifted flames with the variations in air coflow velocity and fuel nozzle diameter","authors":"Kousuo Fu , Neng Tao , Liqiao Jiang , Honghao Wu , Xing Li , Haolin Yang , Xiaohan Wang","doi":"10.1016/j.joei.2024.101939","DOIUrl":"10.1016/j.joei.2024.101939","url":null,"abstract":"<div><div>Many environmental problems caused by the significant increase in carbon emissions are receiving widely attention, while developing ammonia-containing fuel combustion technology is an essential and feasible strategy. In this paper, an experimental study and theoretical analysis of CH<sub>4</sub>/NH<sub>3</sub> jet flame in air coflow were carried out to investigate the effects of air coflow velocity and fuel nozzle diameter variations on the combustion characteristics of ammonia-blended conventional fuels. With the increase of ammonia concentration, the flame chemical luminosity of blended fuels gradually decreased, and the flame root transitioned from bright blue to dark orange. The nozzle diameter and air coflow velocity significantly affected whether the CH<sub>4</sub>/NH<sub>3</sub> jet attached flame can develop into a lifted flame. Meanwhile, three trends and developmental stages of liftoff height with increasing jet velocity were identified for CH<sub>4</sub>/NH<sub>3</sub> turbulent flame, which could be attributed to the ammonia concentration and the flow regime of fuel stream, respectively. The experimental results indicated that the blowoff limit and steady burning region decreased gradually with the increase of ammonia mixing ratio and air coflow velocity, which were positively correlated with the nozzle diameter. Based on the premixed flame model and large-scale mixing model, flammability limit range and relative dilution effect of the fuel mixture were found as important factors in predicting the liftoff height. The results indicated that the modified models could estimate the liftoff height better. In addition, the impact mechanism of air coflow velocity on the blowoff limit in two prediction models was discussed, and a more accurate prediction of the blowoff velocity was achieved by introducing the correction factor <em>k</em>.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"119 ","pages":"Article 101939"},"PeriodicalIF":5.6,"publicationDate":"2024-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Insight into the instability of ammonia-methane laminar diffusion flame

IF 5.6 2区工程技术 Q2 ENERGY & FUELS

Journal of The Energy Institute

Pub Date : 2024-12-20 DOI: 10.1016/j.joei.2024.101961

Guorong Lin , Chenyang Fan , Zheng Fu , Haizhao Li , Ye Liu , Huiyong Du , Bin Xu , Shuo Jin , Mingliang Wei

Ammonia is one of carbon-neutral hydrogen derivatives and is identified as a sustainable fuel for mobile applications. However, the combustion instability of pure ammonia remains a significant challenge. In this study, the combustion instability of ammonia flame with methane as a combustion promoter was investigated using high-speed photography and schlieren techniques on ammonia-methane-air co-flow laminar diffusion flames. It was found that after exceeding a threshold of fuel flow rate (Q_f), the stable laminar flame turned to a regular and reproducible oscillation, accompanying by periodic bulging and separation of the flame. The addition of co-flow air increases flame flickering frequency, which can be reduced by increasing the Q_f. In contrast to the pure methane diffusion flame with distinct luminous zones, the NH₃/CH₄ diffusion flame exhibits a reddish-orange color with no distinguishable luminous zone. Additionally, the addition of ammonia shrinks the appearance of flames, and slightly decreases the flame flickering frequency at 30 % substitution, while increases it at 50 % substitution. A spindle-shape shear layer between the flame and the surrounding air, exhibiting periodic motion during the flickering sequence. The addition of ammonia decreases the maximum shear layer diameter and increases its motion velocity. The co-flow air pushes the vortex formation location downstream, reducing fluctuation amplitude of the shear layer. Ammonia substitution further promotes this downstream shift, potentially lessening the flame flickering.

{"title":"Insight into the instability of ammonia-methane laminar diffusion flame","authors":"Guorong Lin , Chenyang Fan , Zheng Fu , Haizhao Li , Ye Liu , Huiyong Du , Bin Xu , Shuo Jin , Mingliang Wei","doi":"10.1016/j.joei.2024.101961","DOIUrl":"10.1016/j.joei.2024.101961","url":null,"abstract":"<div><div>Ammonia is one of carbon-neutral hydrogen derivatives and is identified as a sustainable fuel for mobile applications. However, the combustion instability of pure ammonia remains a significant challenge. In this study, the combustion instability of ammonia flame with methane as a combustion promoter was investigated using high-speed photography and schlieren techniques on ammonia-methane-air co-flow laminar diffusion flames. It was found that after exceeding a threshold of fuel flow rate (<em>Q</em><sub><em>f</em></sub>), the stable laminar flame turned to a regular and reproducible oscillation, accompanying by periodic bulging and separation of the flame. The addition of co-flow air increases flame flickering frequency, which can be reduced by increasing the <em>Q</em><sub><em>f</em></sub>. In contrast to the pure methane diffusion flame with distinct luminous zones, the NH<sub>3</sub>/CH<sub>4</sub> diffusion flame exhibits a reddish-orange color with no distinguishable luminous zone. Additionally, the addition of ammonia shrinks the appearance of flames, and slightly decreases the flame flickering frequency at 30 % substitution, while increases it at 50 % substitution. A spindle-shape shear layer between the flame and the surrounding air, exhibiting periodic motion during the flickering sequence. The addition of ammonia decreases the maximum shear layer diameter and increases its motion velocity. The co-flow air pushes the vortex formation location downstream, reducing fluctuation amplitude of the shear layer. Ammonia substitution further promotes this downstream shift, potentially lessening the flame flickering.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"119 ","pages":"Article 101961"},"PeriodicalIF":5.6,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143135978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A novel low-NO burner with in-burner high-speed air jet array for ammonia-coal co-firing: Integrating ammonia pyrolysis and deep air staging

IF 5.6 2区工程技术 Q2 ENERGY & FUELS

Journal of The Energy Institute

Pub Date : 2024-12-19 DOI: 10.1016/j.joei.2024.101952

Baohua Zhang , Mingxin Qu , Wenjun He , Bo Pang , Ronghao Yu , Kai Zhang , Zhicheng Xie , Xiaowei Liu , Yishu Xu

Co-firing of the carbon-free fuel ammonia in coal-fired power stations is an effective measure to reduce CO₂ emission. Considering the high nitrogen content in ammonia, ammonia-coal co-firing burner should be crucially and elaborately designed to minimize the NO emission. Here, a novel swirl burner design with in-burner high-speed air jet array (HAJA) was proposed. Structure design and CFD simulations of a 50kWth HAJA burner were performed with a conventional burner as benchmark, and combustion and emission performance under coal firing, ammonia-coal co-firing and pure ammonia firing conditions were evaluated. The results showed that both ammonia-coal blends and coal/ammonia single fuel could be stable burned in the proposed burner. Also importantly, the NO emission of the proposed burner was lower than that of the prototype burner at same combustion conditions. The in-burner air jet array generates high-speed tertiary air jets multipoint-distributed on the periphery and downstream of secondary air, which lengthen the oxygen-lean pyrolysis zone and main combustion zone. This deep air-staged effect helpfully inhibits NO formation and reduces the NO emission as the promoted pyrolysis of ammonia before combustion and lowered the peak temperature, especially for ammonia-coal co-firing. Moreover, the emission performance of HAJA could be flexibly controlled by the velocity of the tertiary air jets at constant total excess air coefficient, and in the simulated scenarios, increasing velocity could reduce the NO formation. Besides, effects of changing the ratio of primary air and secondary air rate on the combustion and emission performance of HAJA burner were also investigated.

{"title":"A novel low-NO burner with in-burner high-speed air jet array for ammonia-coal co-firing: Integrating ammonia pyrolysis and deep air staging","authors":"Baohua Zhang , Mingxin Qu , Wenjun He , Bo Pang , Ronghao Yu , Kai Zhang , Zhicheng Xie , Xiaowei Liu , Yishu Xu","doi":"10.1016/j.joei.2024.101952","DOIUrl":"10.1016/j.joei.2024.101952","url":null,"abstract":"<div><div>Co-firing of the carbon-free fuel ammonia in coal-fired power stations is an effective measure to reduce CO<sub>2</sub> emission. Considering the high nitrogen content in ammonia, ammonia-coal co-firing burner should be crucially and elaborately designed to minimize the NO emission. Here, a novel swirl burner design with in-burner high-speed air jet array (HAJA) was proposed. Structure design and CFD simulations of a 50kWth HAJA burner were performed with a conventional burner as benchmark, and combustion and emission performance under coal firing, ammonia-coal co-firing and pure ammonia firing conditions were evaluated. The results showed that both ammonia-coal blends and coal/ammonia single fuel could be stable burned in the proposed burner. Also importantly, the NO emission of the proposed burner was lower than that of the prototype burner at same combustion conditions. The in-burner air jet array generates high-speed tertiary air jets multipoint-distributed on the periphery and downstream of secondary air, which lengthen the oxygen-lean pyrolysis zone and main combustion zone. This deep air-staged effect helpfully inhibits NO formation and reduces the NO emission as the promoted pyrolysis of ammonia before combustion and lowered the peak temperature, especially for ammonia-coal co-firing. Moreover, the emission performance of HAJA could be flexibly controlled by the velocity of the tertiary air jets at constant total excess air coefficient, and in the simulated scenarios, increasing velocity could reduce the NO formation. Besides, effects of changing the ratio of primary air and secondary air rate on the combustion and emission performance of HAJA burner were also investigated.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"119 ","pages":"Article 101952"},"PeriodicalIF":5.6,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Progress in CFD simulation for ammonia-fueled internal combustion engines and gas turbines

IF 5.6 2区工程技术 Q2 ENERGY & FUELS

Journal of The Energy Institute

Pub Date : 2024-12-19 DOI: 10.1016/j.joei.2024.101951

Ning-Ning Yao , Yi-Feng Chen , Li-Ming Wei , Qi-Yu Xu , Wei-Guo Pan

With the urgent demand for global carbon neutrality, ammonia is increasingly seen as a promising alternative to traditional fossil fuels for use in internal combustion engines (ICEs) and gas turbines (GTs). However, the practical industrial applications have faced obstacles due to certain unfavorable combustion characteristics of ammonia. This necessitates the development of advanced and innovative computational tools to enable the clean and efficient utilization of ammonia fuels. The combination of lower cost, enhanced controllability, and detailed information on local and global fluid flow, heat transfer, and mass transfer phenomena provided by Computational Fluid Dynamics (CFD) simulations makes it indispensable for the development and optimization of ammonia-fueled ICEs and GTs, paving the way for cleaner and more efficient propulsion systems within the energy sector. Herein, this work systematically introduces and analyzes ammonia-fueled ICEs and GTs along with their numerical simulation methods, models, and chemical kinetic mechanisms. The similarities and differences of various simulation methods in ammonia fuel-related combustion are summarized, highlighting those methodologies applied in the numerical studies under the corresponding conditions, and focusing on the current state, and shortcomings of utilzing CFD in ICEs and GTs. By providing this comprehensive information, options and references are provided for related numerical simulation research. Finally, based on the results of the current simulation studies, future goals are indicated for advancing CFD simulation of ammonia-fueled ICEs and GTs, which will contribute to the low-carbon transition of industry.

{"title":"Progress in CFD simulation for ammonia-fueled internal combustion engines and gas turbines","authors":"Ning-Ning Yao , Yi-Feng Chen , Li-Ming Wei , Qi-Yu Xu , Wei-Guo Pan","doi":"10.1016/j.joei.2024.101951","DOIUrl":"10.1016/j.joei.2024.101951","url":null,"abstract":"<div><div>With the urgent demand for global carbon neutrality, ammonia is increasingly seen as a promising alternative to traditional fossil fuels for use in internal combustion engines (ICEs) and gas turbines (GTs). However, the practical industrial applications have faced obstacles due to certain unfavorable combustion characteristics of ammonia. This necessitates the development of advanced and innovative computational tools to enable the clean and efficient utilization of ammonia fuels. The combination of lower cost, enhanced controllability, and detailed information on local and global fluid flow, heat transfer, and mass transfer phenomena provided by Computational Fluid Dynamics (CFD) simulations makes it indispensable for the development and optimization of ammonia-fueled ICEs and GTs, paving the way for cleaner and more efficient propulsion systems within the energy sector. Herein, this work systematically introduces and analyzes ammonia-fueled ICEs and GTs along with their numerical simulation methods, models, and chemical kinetic mechanisms. The similarities and differences of various simulation methods in ammonia fuel-related combustion are summarized, highlighting those methodologies applied in the numerical studies under the corresponding conditions, and focusing on the current state, and shortcomings of utilzing CFD in ICEs and GTs. By providing this comprehensive information, options and references are provided for related numerical simulation research. Finally, based on the results of the current simulation studies, future goals are indicated for advancing CFD simulation of ammonia-fueled ICEs and GTs, which will contribute to the low-carbon transition of industry.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"119 ","pages":"Article 101951"},"PeriodicalIF":5.6,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143135892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Simulation of selective catalytic reduction of NO and oxidation of CO and C7H8 over V2O5-TiO2 catalyst

IF 5.6 2区工程技术 Q2 ENERGY & FUELS

Journal of The Energy Institute

Pub Date : 2024-12-19 DOI: 10.1016/j.joei.2024.101956

Qingyuan Hua, Boxiong Shen

A three-dimensional model of a single-channel honeycomb NH₃-SCR catalytic converter was developed to simulate the catalytic reduction of NO and the simultaneous oxidation of CO and C₇H₈. The accuracy of the model was validated against experimental data. The effects of different operation conditions (such as space velocity, temperature, and inlet concentration) on the conversion efficiency of NO and CO were investigated, along with the distribution of gas components at various locations within the catalyst channel and along the catalyst wall. Compared to inlet gas concentrations, space velocity and temperature had a more significant impact on NO catalytic reduction and CO oxidation. Additionally, the oxidation behavior of toluene (C₇H₈) and its influence on the removal efficiency of NO and CO were analyzed by the simulation at the same time.

引用次数: 0

Investigation on the role of hydrogen in polyethylene hydropyrolysis process via ReaxFF molecular dynamic simulation

IF 5.6 2区工程技术 Q2 ENERGY & FUELS

Journal of The Energy Institute

Pub Date : 2024-12-18 DOI: 10.1016/j.joei.2024.101953

Guanqun Luo , Xiangkun Zhang , Linjia Yin , Jing Su , Kaige Wang

Pyrolysis is one of the promising ways to valorize waste plastics into valuable products, and the introduction of hydrogen can further enhance the quality of products. In this study, the role of hydrogen in the catalyst-free hydropyrolysis of polyethylene (PE) at different temperatures was systematically investigated via ReaxFF molecular dynamic simulation. The accuracy of the model was validated by comparing with the thermogravimetric experimental results and the corresponding kinetics, as well as an appropriate degree of polymerization of PE was screened. The results indicate that temperature played a decisive role in the hydropyrolysis of PE. An increase in temperature significantly accelerated the rate of breakage of C-C and C-H bonds in PE, thus improving the yield and shifting the product distribution towards low carbon numbers. The initial hydrogen in the system had an almost negligible effect on the yield, while its effect on the product distribution was opposite to the temperature. The presence of hydrogen slowed down the stretching process of the C-C bond through intermolecular forces, thus inhibiting the cleavage of different types of C-C bonds. As a result, the product distribution shifted to the high carbon numbers and the average unsaturation of products decreased. This effect of hydrogen gradually diminished when the temperature increased. In addition, high temperature also promoted the dehydrogenation reaction rate of PE and its depolymerization intermediates, which increased the average unsaturation of products; however, the involvement of hydrogen in the chemical reaction during the middle and late stages of the reaction at high temperatures in turn led to a certain decrease in the average unsaturation of the products. This study provides a theoretical basis for the design and optimization of PE hydropyrolysis process.

{"title":"Investigation on the role of hydrogen in polyethylene hydropyrolysis process via ReaxFF molecular dynamic simulation","authors":"Guanqun Luo , Xiangkun Zhang , Linjia Yin , Jing Su , Kaige Wang","doi":"10.1016/j.joei.2024.101953","DOIUrl":"10.1016/j.joei.2024.101953","url":null,"abstract":"<div><div>Pyrolysis is one of the promising ways to valorize waste plastics into valuable products, and the introduction of hydrogen can further enhance the quality of products. In this study, the role of hydrogen in the catalyst-free hydropyrolysis of polyethylene (PE) at different temperatures was systematically investigated via ReaxFF molecular dynamic simulation. The accuracy of the model was validated by comparing with the thermogravimetric experimental results and the corresponding kinetics, as well as an appropriate degree of polymerization of PE was screened. The results indicate that temperature played a decisive role in the hydropyrolysis of PE. An increase in temperature significantly accelerated the rate of breakage of C-C and C-H bonds in PE, thus improving the yield and shifting the product distribution towards low carbon numbers. The initial hydrogen in the system had an almost negligible effect on the yield, while its effect on the product distribution was opposite to the temperature. The presence of hydrogen slowed down the stretching process of the C-C bond through intermolecular forces, thus inhibiting the cleavage of different types of C-C bonds. As a result, the product distribution shifted to the high carbon numbers and the average unsaturation of products decreased. This effect of hydrogen gradually diminished when the temperature increased. In addition, high temperature also promoted the dehydrogenation reaction rate of PE and its depolymerization intermediates, which increased the average unsaturation of products; however, the involvement of hydrogen in the chemical reaction during the middle and late stages of the reaction at high temperatures in turn led to a certain decrease in the average unsaturation of the products. This study provides a theoretical basis for the design and optimization of PE hydropyrolysis process.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"119 ","pages":"Article 101953"},"PeriodicalIF":5.6,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143135981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Numerical study on flame structure and NOx generation under different Coal/NH3 co-firing strategies in a 1000 MW utility boiler

IF 5.6 2区工程技术 Q2 ENERGY & FUELS

Journal of The Energy Institute

Pub Date : 2024-12-18 DOI: 10.1016/j.joei.2024.101957

Mingyu Liu , Sheng Chen , Hongwei Zhu , Jingying Xu

Coal/ammonia (NH₃) co-firing in power plants is acknowledged as a promising technology for mitigating carbon emissions at source. However, due to the high nitrogen content in NH₃, there is a risk of NO_x emissions. This study conducts a numerical simulation on coal/NH₃ co-combustion in a 1000 MW ultra-supercritical boiler, exploring the impacts of injection strategies on combustion and NO generation characteristics. The strategies investigated include: (1) uniformly injecting NH₃ through all burners, (2) non-uniform NH₃ injection through selected burners, and (3) NH₃ injection via NH₃ nozzles. Results reveal that, when NH₃ is uniformly injected through all burners, a high co-firing ratio (40 % by calorific value) is needed to establish an elongated flame structure at the burner outlet. Under this condition, NO concentrations at the furnace outlet are reduced to 142.3 ppm, respectively, which are lower than that in pure coal combustion. Non-uniform NH₃ injection through selected burners leads to the formation of elongated flame at lower NH₃ co-firing ratios, thus diminishing NO production. When introduced through nozzles at the lower section of the primary combustion zone, NH₃ tends to move downward to the ash hopper, where intense pyrolysis occurs, limiting the conversion of NH₃ to NO and reducing NO emissions.

{"title":"Numerical study on flame structure and NOx generation under different Coal/NH3 co-firing strategies in a 1000 MW utility boiler","authors":"Mingyu Liu , Sheng Chen , Hongwei Zhu , Jingying Xu","doi":"10.1016/j.joei.2024.101957","DOIUrl":"10.1016/j.joei.2024.101957","url":null,"abstract":"<div><div>Coal/ammonia (NH<sub>3</sub>) co-firing in power plants is acknowledged as a promising technology for mitigating carbon emissions at source. However, due to the high nitrogen content in NH<sub>3</sub>, there is a risk of NO<sub>x</sub> emissions. This study conducts a numerical simulation on coal/NH<sub>3</sub> co-combustion in a 1000 MW ultra-supercritical boiler, exploring the impacts of injection strategies on combustion and NO generation characteristics. The strategies investigated include: (1) uniformly injecting NH<sub>3</sub> through all burners, (2) non-uniform NH<sub>3</sub> injection through selected burners, and (3) NH<sub>3</sub> injection via NH<sub>3</sub> nozzles. Results reveal that, when NH<sub>3</sub> is uniformly injected through all burners, a high co-firing ratio (40 % by calorific value) is needed to establish an elongated flame structure at the burner outlet. Under this condition, NO concentrations at the furnace outlet are reduced to 142.3 ppm, respectively, which are lower than that in pure coal combustion. Non-uniform NH<sub>3</sub> injection through selected burners leads to the formation of elongated flame at lower NH<sub>3</sub> co-firing ratios, thus diminishing NO production. When introduced through nozzles at the lower section of the primary combustion zone, NH<sub>3</sub> tends to move downward to the ash hopper, where intense pyrolysis occurs, limiting the conversion of NH<sub>3</sub> to NO and reducing NO emissions.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"119 ","pages":"Article 101957"},"PeriodicalIF":5.6,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143135983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Recovering value-added hydrocarbons from aluminum foil-laminated plastic residue through catalytic pyrolysis using WO3 supported on rice husk ash

IF 5.6 2区工程技术 Q2 ENERGY & FUELS

Journal of The Energy Institute

Pub Date : 2024-12-18 DOI: 10.1016/j.joei.2024.101955

Edyjancleide Rodrigues da Silva , Gabriel Henrique de Oliveira Santos , Joemil Oliveira de Deus Junior , Júlio de Andrade Oliveira Marques , Dulce Maria de Araújo Melo , José Luiz Francisco Alves , Renata Martins Braga

Following a circular economy strategy, recovering value-added hydrocarbons from plastic residues through catalytic pyrolysis is an innovative and promising approach for both resource conservation and refuse valorization. The main objective of the current work is to investigate the impact of tungsten trioxide (WO₃) supported on rice husk ash (RHA) as a new, low-cost catalyst on the flash pyrolysis of aluminum foil-laminated plastic residue. The catalyst performance was investigated using a micro-furnace temperature-programmable pyrolyzer interfaced with gas chromatographic separation and mass spectrometry detection. The energy-related attributes of aluminum foil-laminated plastic residue have confirmed its potential as raw material for pyrolytic oil production, owing to its high energy content (31.76 MJ kg⁻¹), volatile matter content (82.5 wt%), moderate ash content (17.5 wt%), negligible fixed carbon content (below 0.01 wt%), and predominant mass loss below 500 °C. The catalytic test results demonstrated that the concentration of alkanes increased by 2.5-fold and cyclic aliphatic compounds by 1.9-fold when utilizing the WO₃/RHA catalyst compared to non-catalytic pyrolysis. From the hydrocarbon distributions, success was achieved by the WO₃/RHA catalyst in the cracking of heavy hydrocarbons (above C₁₂) into valuable light hydrocarbons (C₅–C₁₂). The results permit us to conclude that utilizing the WO₃/RHA catalyst enhances the yield of alkanes and cyclic aliphatic compounds within the C₅–C₁₂ range in the condensable volatile products, which are valuable gasoline-range hydrocarbons. Utilizing the proposed catalyst offers a potentially low-cost way to convert plastic waste into gasoline-range transportation fuel, enabling the achievement of a circular economy for plastic residues through catalytic pyrolysis, unlike traditional treatment methods.

{"title":"Recovering value-added hydrocarbons from aluminum foil-laminated plastic residue through catalytic pyrolysis using WO3 supported on rice husk ash","authors":"Edyjancleide Rodrigues da Silva , Gabriel Henrique de Oliveira Santos , Joemil Oliveira de Deus Junior , Júlio de Andrade Oliveira Marques , Dulce Maria de Araújo Melo , José Luiz Francisco Alves , Renata Martins Braga","doi":"10.1016/j.joei.2024.101955","DOIUrl":"10.1016/j.joei.2024.101955","url":null,"abstract":"<div><div>Following a circular economy strategy, recovering value-added hydrocarbons from plastic residues through catalytic pyrolysis is an innovative and promising approach for both resource conservation and refuse valorization. The main objective of the current work is to investigate the impact of tungsten trioxide (WO<sub>3</sub>) supported on rice husk ash (RHA) as a new, low-cost catalyst on the flash pyrolysis of aluminum foil-laminated plastic residue. The catalyst performance was investigated using a micro-furnace temperature-programmable pyrolyzer interfaced with gas chromatographic separation and mass spectrometry detection. The energy-related attributes of aluminum foil-laminated plastic residue have confirmed its potential as raw material for pyrolytic oil production, owing to its high energy content (31.76 MJ kg<sup>−1</sup>), volatile matter content (82.5 wt%), moderate ash content (17.5 wt%), negligible fixed carbon content (below 0.01 wt%), and predominant mass loss below 500 °C. The catalytic test results demonstrated that the concentration of alkanes increased by 2.5-fold and cyclic aliphatic compounds by 1.9-fold when utilizing the WO<sub>3</sub>/RHA catalyst compared to non-catalytic pyrolysis. From the hydrocarbon distributions, success was achieved by the WO<sub>3</sub>/RHA catalyst in the cracking of heavy hydrocarbons (above C<sub>12</sub>) into valuable light hydrocarbons (C<sub>5</sub>–C<sub>12</sub>). The results permit us to conclude that utilizing the WO<sub>3</sub>/RHA catalyst enhances the yield of alkanes and cyclic aliphatic compounds within the C<sub>5</sub>–C<sub>12</sub> range in the condensable volatile products, which are valuable gasoline-range hydrocarbons. Utilizing the proposed catalyst offers a potentially low-cost way to convert plastic waste into gasoline-range transportation fuel, enabling the achievement of a circular economy for plastic residues through catalytic pyrolysis, unlike traditional treatment methods.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"119 ","pages":"Article 101955"},"PeriodicalIF":5.6,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143135980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Mechanism investigation of the effect of coal gangue composition on the conversion of ammonia and nitric oxide on its surface

IF 5.6 2区工程技术 Q2 ENERGY & FUELS

Journal of The Energy Institute

Pub Date : 2024-12-18 DOI: 10.1016/j.joei.2024.101954

Guoqing Chen , Xinwei Yang , Zhuo Chang , Yuanyuan Zhang , Fengling Yang , Jing Wang

Ammonia (NH₃) has emerged as a zero-carbon fuel that can be co-firing with coal. This co-firing practice offers a dual advantage: it reduces carbon emissions to some extent while also enhancing the utilization rate of low-calorific-value fuels such as coal gangue. In this study, we investigated the adsorption and conversion of NH₃ in coal gangue under different atmospheres and temperatures and its influence on NO reduction by means of a fixed-bed reaction system and characterization methods such as SEM, XRD and XPS. Findings reveal that under the atmosphere containing only NH₃ and N₂, the higher content of Fe₂O₃ and organic components in Changzhi gangue (CS) leads to heightened conversion activity of NH₃. Of these, NO will be produced as a byproduct of the reaction between NH₃ and the oxygen in the coal gangue. Under the coexistence of NH₃ and O₂, CS had a surface adsorbed O content of 67.47 %, which exceeded that of PS. The oxidation reaction of NH₃ was contributed by the surface acidic sites of CS with different active ingredients and the synergistic effect of chemisorbed O. As a result, the CS outlet had a higher NH₃ conversion (96.86 %) and NO selectivity (99.15 %) than the PS outlet. Under the coexistence of NH₃ and NO, the NO reduction efficiency of CS reaches 99.98 % at 850 °C, and the ability of NO to oxidize NH₃ is weaker than the ability of O₂. Under the coexistence of NH₃, NO and O₂, the oxidation of NH₃ gradually dominated with increasing temperature and led to the production of additional NO.

{"title":"Mechanism investigation of the effect of coal gangue composition on the conversion of ammonia and nitric oxide on its surface","authors":"Guoqing Chen , Xinwei Yang , Zhuo Chang , Yuanyuan Zhang , Fengling Yang , Jing Wang","doi":"10.1016/j.joei.2024.101954","DOIUrl":"10.1016/j.joei.2024.101954","url":null,"abstract":"<div><div>Ammonia (NH<sub>3</sub>) has emerged as a zero-carbon fuel that can be co-firing with coal. This co-firing practice offers a dual advantage: it reduces carbon emissions to some extent while also enhancing the utilization rate of low-calorific-value fuels such as coal gangue. In this study, we investigated the adsorption and conversion of NH<sub>3</sub> in coal gangue under different atmospheres and temperatures and its influence on NO reduction by means of a fixed-bed reaction system and characterization methods such as SEM, XRD and XPS. Findings reveal that under the atmosphere containing only NH<sub>3</sub> and N<sub>2</sub>, the higher content of Fe<sub>2</sub>O<sub>3</sub> and organic components in Changzhi gangue (CS) leads to heightened conversion activity of NH<sub>3</sub>. Of these, NO will be produced as a byproduct of the reaction between NH<sub>3</sub> and the oxygen in the coal gangue. Under the coexistence of NH<sub>3</sub> and O<sub>2</sub>, CS had a surface adsorbed O content of 67.47 %, which exceeded that of PS. The oxidation reaction of NH<sub>3</sub> was contributed by the surface acidic sites of CS with different active ingredients and the synergistic effect of chemisorbed O. As a result, the CS outlet had a higher NH<sub>3</sub> conversion (96.86 %) and NO selectivity (99.15 %) than the PS outlet. Under the coexistence of NH<sub>3</sub> and NO, the NO reduction efficiency of CS reaches 99.98 % at 850 °C, and the ability of NO to oxidize NH<sub>3</sub> is weaker than the ability of O<sub>2</sub>. Under the coexistence of NH<sub>3</sub>, NO and O<sub>2</sub>, the oxidation of NH<sub>3</sub> gradually dominated with increasing temperature and led to the production of additional NO.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"119 ","pages":"Article 101954"},"PeriodicalIF":5.6,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143135982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0