Numerical and experimental studies on effects of moisture content on combustion characteristics of simulated municipal solid wastes in a fixed bed

Sun, Rui; Ismail, Tamer M.; Ren, Xiaohan; elsalam, Sahar Mahmoud Abd

doi:10.1016/j.wasman.2015.02.018

Cited by 53 publications

(20 citation statements)

References 25 publications

(19 reference statements)

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“…When moisture exists, effect of chlorine precipitation from municipal solid waste combustion is that combustion temperature is meaningfully reduced with the same chlorine precipitation rate. When the presence of moisture, sawdust waste that is not free of volatile chlorine released HCl gas during the incineration process after the inorganic chloride salt is obtained by transfer [15]. because of the existence of kitchen waste with high moisture content from municipal solid waste, the amount of HCl released during combustion of municipal solid waste increases.…”

Section: Hcl Release Characteristic Of Municipalmentioning

confidence: 99%

“…In the case of full combustion, chlorine in poly-vinyl chloride (PVC) substances can be converted into HCl. When the presence of moisture, the increase of moisture in municipal solid waste can provide more H free radicals under high temperature combustion conditions, so that C free radicals have more opportunities to effectively collide with H free radicals [15]. The release has little effect at low temperature, but it aggravates the release of HCl during combustion at medium-high temperature.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Municipal Solid Waste Torrefaction and Classification Pretreatment on Hydrogen Chloride Release

Hu¹,

Ning²,

Zhu³

et al. 2021

SJEE

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The incineration treatment of municipal solid waste is widely used, but gas-phase hydrogen chloride (HCl) generated during the incineration seriously threatens the heating surface of boiler tail, and even causes serious harm to environment. Through incineration experiments, this paper found that many factors (temperature, oxygen concentration, residence time and moisture content) affect the HCl emission characteristics in the process of municipal solid waste incineration treatment. In order to effectively cut back the HCl emission in incineration treatment of municipal solid waste, this paper proposes torrefaction and classification pretreatment of municipal solid waste. Torrefaction pretreatment has a significant inhibitory effect on HCl emission during the incineration of mixed municipal solid waste. At the same time, compared with the incineration treatment of mixed municipal solid waste, sawdust and plastic municipal solid waste of the same quality after classification pretreatment can effectively curb HCl emissions within the entire temperature range. In particular, HCl emissions are reduced by 35% during sawdust incineration treatment at 400°C. Furthermore, by studying the reaction mechanics of HCl generation during combustion at different temperatures, and the reaction rate of HCl generation is: mixed municipal solid waste >plastic >sawdust. Therefore, this paper believes that torrefaction and classification pretreatment of mixed municipal solid waste is beneficial to inhibit the precipitation of chlorine during the incineration process and promotes the resource utilization of municipal solid waste, which is of significant significance for energy conservation and emission reduction.

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Section: Hcl Release Characteristic Of Municipalmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of Municipal Solid Waste Torrefaction and Classification Pretreatment on Hydrogen Chloride Release

Hu¹,

Ning²,

Zhu³

et al. 2021

SJEE

View full text Add to dashboard Cite

show abstract

“…A one-dimensional fixed-bed system has been typically used by researchers at home and abroad to study the grate-fired process. [22][23][24][25] This approach follows the Lagrangian method, where time is used to simulate the space and the local changes are used to reflect the global changes. In this approach, the combustion results at different times are superposed, and the combustion characteristics and products of different spaces on the real grate are simulated and obtained.…”

Section: Small-scale One-dimensional Fixedbed Systemmentioning

confidence: 99%

Effect of temperature and reaction atmosphere on nitric oxide emission during a char grate‐fired process in local flue gas recirculation

Yang

Gao

et al. 2021

Can J Chem Eng

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Local flue gas recirculation (LFGR) is an effective technology for reducing nitrogen oxide (NO x ) emissions from coal-fired industrial boilers. The temperature and reaction atmosphere changes when flue gas is recycled, thereby affecting both the grate-fired process and NO x emission. In this paper, the boundary of LFGR was simulated by changing the experimental parameters. On a small-scale one-dimensional fixed-bed system, the effects of temperature, O 2 flux, and CO, CO 2 , and recycled NO concentrations on oxidation-reduction layering and char nitrogen conversion during the char grate-fired process were studied. The effect of temperature and recycled flue gas components on nitric oxide (NO) emissions during the char grate-fired process was then analyzed based on the mass proportion of oxygen-absent and oxygen-present parts. The results show that, with the introduction of recycled flue gas, increasing the temperature will also increase the reduction layer mass and proportion, and, subsequently, inhibit NO emissions; increasing the O 2 flux will reduce the reduction layer proportion and subsequently promote NO emissions; increasing the CO and CO 2 concentrations will reduce the NO emitted from the oxidation layer, yet has limited effects on the entire char bed; and recycled NO will significantly reduce the NO emissions. The effect of LFGR-induced changes in temperature and reaction atmosphere on NO emissions can be ascribed to the negative effect of the increase in O 2 flux and the positive effect of the increase in temperature and CO, CO 2 , and recycled NO concentrations.

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“…The proposed k−ε model also describes the turbulent kinetic energy and the dissipation rate, i.e., the exchange between the amount of turbulence and the computation time. 38 This code should achieve a converged solution over 1500 iterations; given the limits of our computer capacity and other issues, we stopped at 1500 iterations. The interactions between the gas and solid phases are simulated, and the convective heat exchange and momentum (the drag in the gas and solid phases) are incorporated into the model.…”

Section: Computational Modeling Approachmentioning

confidence: 99%

“…In the present work, a theoretical and experimental study was conducted on a fixed bed for corn straw combustion. In comparison to our previous mathematical model and simulations − and our experimental work on a fixed bed, the mathematical model has been improved and is applied to assess the complicated combustion behavior of corn in a current reactor based on changes in the particle size. Using a current experimental furnace, the results were obtained to validate the present COMMENT-Code (Combustion Mathematics and Energy Transport) based on comparisons between the existing experimental and model results.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Chopped Corn Straw Lengths for Combustion in a Fixed Bed Using a Numerical Model

et al. 2018

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In this paper, both a numerical model and an experimental study were developed to determine the important parameters of corn length for combustion behavior in a fixed-bed reactor. As an important factor impacting thermal conversion, changes in the burning rate follow variations in corn length, which then affect gas emissions. As a result of insufficient knowledge concerning the mechanisms of complex combustion, the development of a combustion system has been restricted. Modeling of this combustion system will complement experimental data; however, improving such a model is challenging as a result of the unique characteristics of corn, such as its moisture content and porosity. The results show that corn straw with a shorter length has a shorter ignition time, increased bed temperature, and reduced amounts of unburned carbon in the ash residues. Furthermore, the burning of shorter corn straw causes high emission concentrations from pyrolysis products, such as CH 4 , CO, and most prevalently NO, near the grate, which indicates the beginning of the char oxidation stage. Corn straw with longer lengths increases the difficulty of accurately modeling the irregular shape of corn straw particles for theoretical calculations. In addition, in an actual bed, local bed structures that have not been uniformly mixed result in uncertainties in the flame propagation as well as the time at which the fuel is ignited. The application of numerical modeling allows for a more detailed description of the corn combustion process and can be used as a reference to develop biomass combustion in a large system.

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Numerical and experimental studies on effects of moisture content on combustion characteristics of simulated municipal solid wastes in a fixed bed

Cited by 53 publications

References 25 publications

Effects of Municipal Solid Waste Torrefaction and Classification Pretreatment on Hydrogen Chloride Release

Effects of Municipal Solid Waste Torrefaction and Classification Pretreatment on Hydrogen Chloride Release

Effect of temperature and reaction atmosphere on nitric oxide emission during a char grate‐fired process in local flue gas recirculation

Assessment of Chopped Corn Straw Lengths for Combustion in a Fixed Bed Using a Numerical Model

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