Municipal Solid Waste Incineration Plant Research Articles

Recycling of fly ash to synthesize zeolites for efficient removal of dioxins

The large amount of fly ash (FA) produced by coal-fired power plants places tremendous pressure on the environment. Meanwhile, toxic dioxins emitted from municipal solid waste incineration plants are of great concern. To address these challenges, a win-win approach was proposed to re-utilize FA for synthesis of zeolite materials for dioxins adsorption. The results indicate that the Si/Al molar ratio in the liquid-phase precursor significantly influences the distribution of Si-Al 4-membered rings (Si/Al=1) and Si-Al 4-membered rings (Si/Al=3) in the system. These units are key secondary structures of the zeolite skeleton, determining the proportions of A-type and X-type zeolites in the product. With the increasing Si/Al molar ratio of precursor, the specific surface area and Si/Al molar ratio of zeolites derived from fly ash (ZFA) both increased, while they played a positive and negative role in dioxins adsorption, respectively. The adsorption of dioxins by ZFA peaked at a Si/Al molar ratio of precursor of 1.5, reaching 4.13×105 pg I-TEF/g, surpassing activated carbon by 1.46 times. This study not only elucidates the mechanism of Si/Al molar ratio of precursor on crystalline transformation of ZFA, but also confirms the potential of ZFA in dioxins adsorption.

Potassium release and mitigation by additives in different biomass combustion systems

Deposition formation on heat-exchanging surfaces and corrosion limit the use and efficiency of solid biomass combustion systems. The main influencing factors on these ash-related problems are the potassium content, the form in which the potassium is bound to the fuel matrix, and the temperature in the combustion system. To avoid these deposition problems, choosing the right fuel for a particular combustion system and vice versa is important.In this work, the temperature in fluidized bed, grate firing, and suspension combustion systems is analyzed by using the example of the power plants Altenstadt and Avedøre, as well as a European municipal solid waste incineration plant. Additionally, the temperature-resolved potassium release of ten different biofuels is analyzed in an electrothermal vaporization unit (ETV) connected to an inductively coupled plasma optical emission spectrometer (ICP-OES). The potential of additives to mitigate the potassium release is analyzed by adding kaolin and coal fly ash to miscanthus, torrefied wood, and beechwood.The results show that hardly any potassium is released into the gas phase at the typical temperatures of fluidized bed systems. Most of the potassium release occurs between 1000 °C and 1400 °C, the typical temperature range of grate combustion systems. This shows that reducing the temperature of the fuel on the grate could drastically reduce the potassium release. However, due to the negative effect on the efficiency, other measures, such as using additives for capturing potassium species, are favored. At the temperatures in suspension-fired combustion systems, almost all potassium is released into the gas phase, and additives cannot mitigate the release at these temperatures. Additives can shift the potassium release of miscanthus and torrefied wood while showing no positive effect when mixed with beechwood.All in all, this work enables a quantitative comparison of various biofuels and a rough evaluation of the suitability of a fuel regarding the deposition formation for different combustion systems.

Prediction and Feed-In Tariffs of Municipal Solid Waste Generation in Beijing: Based on a GRA-BiLSTM Model

To cope with the increasing energy demand of people and solve the problem of a “Garbage Siege”, most cities have begun to adopt waste power generation (WTE). Compared to other WTE technologies, incineration has proven to be the most efficient technology for municipal solid waste (MSW) treatment. Therefore, to further explore the economic feasibility of MSW incineration plant construction, this study established a multi-factor prediction of MSW generation based on the GRA-BiLSTM model. By fully considering the relationship between the change in feed-in tariff (FIT) and the building of an incineration plant in Beijing, the economic feasibility of building an incineration plant is discussed based on the three scenarios set. The experimental results showed that (1) the combined model based on the GRA-BiLSTM showed good applicability for predicting MSW generation in Beijing, with MAE, MAPE, RMSE, and R2 values of 12.47, 5.97%, 18.5580, and 0.8950, respectively. (2) Based on the three scenarios set, the incineration power generation of Beijing MSW will show varying degrees of growth in 2022–2035. In order to meet future development, Beijing needs to build seven new incinerators, and the incineration rate should reach 100%. (3) According to setting different feed-in tariffs, based on the economic feasibility analysis, it is found that the feed-in tariff of MSW incineration for power generation in Beijing should be no less than $0.522/kWh. The government should encourage the construction of incineration plants and give policy support to enterprises that build incineration plants.

Residual, sequential extraction, and ecological risk assessment of some metals in ash from municipal solid waste incineration, Vietnam

Abstract Incineration plants for electricity generation have offered a solution to the challenges of domestic solid waste treatment in many countries. However, their emissions, fly ash (FA) and bottom ash (BA), have had a detrimental impact on environmental quality. This study investigated the morphology, element composition, and concentration of metals in FA and BA from municipal solid waste incineration plants using scanning electronic microscopy/energy-dispersive X-ray and inductively coupled plasma mass spectrometry techniques. It also evaluated the distribution ratios of metal species across five fractions: exchangeable, carbonate-bound, oxide-bound, organic-bound, and sulfide-bound, and residual. The total metal content in both FA and BA was comparable, with calcium having the highest concentration (28,170–135,130 mg·kg−1 dry weight) and silver having the lowest (5.26–19.3 mg·kg−1 dry weight). However, the percentage proportion of metals differed between the extracted fractions. Except for cadmium in FA, ecological risk assessment indicated low direct bioavailability and potential risk of metals in both FA and BA. These findings contribute to the hazard assessment of FA and BA generated from waste incinerators and provide a scientific basis for developing treatment techniques for this type of waste.

Occurrence, distribution and annual emissions of chlorinated paraffins in hazardous byproducts from municipal solid waste incineration plants in South China

Nowadays incineration technology has become the most mainstream way for the disposal of municipal wastes. Short chain chlorinated paraffins (SCCPs) and medium chain chlorinated paraffins (MCCPs) are currently classified as new persistent organic pollutants (POPs) and candidate POPs under the Stockholm Convention, respectively. However, the occurrence and contamination characteristics of these main hazardous byproducts (e.g., leachate, fly ash, and bottom ash) from municipal solid waste incineration (MSWI) plants have remained unknown. This study focused on the SCCPs and MCCPs (defined as CPs) contamination and their annual emissions from leachate, fly ash, and bottom ash among three typical MSWI plants in Shenzhen, South China. Compared to the dissolved phase of the leachate, higher concentrations of CPs were detected in the adsorbed phase. The total concentrations of CPs ranged from lower method detection limits (<MDLs) to 448 ng/g in fly ash and 124 to 7230 ng/g in bottom ash. The ratios of MCCPs to SCCPs were generally >1 in leachate (i.e., adsorbed phase) and bottom ash, while the opposite results were found in fly ash. The dominant SCCP congener groups were C10Cl6–7 in leachate and fly ash, and C13Cl6–7 in bottom ash. The dominant MCCP congener groups were C14Cl7–8 in leachate, fly ash and bottom ash samples. Principal component analysis (PCA) revealed the dominant CPs in fly ash were obviously different from those in leachate and bottom ash. Estimated total annual emissions of CPs from the three main hazardous byproducts generated from typical MSWI plants were estimated between 66.2 and 7510 kg/y and bottom ash contributed the most to the CP emissions. Overall, this study is the first report on CP contamination in hazardous byproducts from MSWI plants, and can provide basic data support for CP contamination control.

Fate of sulfur and chlorine during co-incineration of municipal solid waste and industrial organic solid waste

In China, the co-incineration of municipal solid waste (MSW) with industrial organic solid waste (IOSW) is increasingly adopted. Compared with MSW, IOSW contains higher levels of sulfur (S) and chlorine (Cl), presenting significant challenges for controlling S/Cl emissions in MSW incineration plants. In this study, the impact of co-incinerating IOSW was investigated in a 500 t/d incinerator grate, focusing on the emissions and transformation behaviors of S/Cl. IOSW, with a consistent sulfur content of about 0.22 wt% and a more variable chlorine content averaging 0.53 wt%, contains over 40 % organic sulfur and >90 % organic chlorine, higher than in MSW. The results of co-incineration experiments showed that the median SO2 concentration in the flue gas was stable at 50 mg/m3, while HCl concentration decreased initially and then increased as the co-incineration ratio of IOSW rose from 20 % to 40 %. Furthermore, the concentrations of SO2 and HCl were not significantly influenced by wind flow but were positively affected by the rising furnace temperatures. Besides, the co-incineration ratio had minimal impact on sulfur in fly ash before deacidification, primarily derived from the gas stream. However, the (Na + K)/Cl ratio in fly ash progressively increased from 1.5 to 1.9, and the Ca content decreased from 0.35 % to 0.15 % as the co-incineration ratio rose to 40 %, indicating more chlorine migration into the fly ash at higher co-incineration rates. This research offers essential guidance for effectively controlling pollutant emissions during the co-incineration of IOSW, specifically the S/Cl pollutants.

Simultaneous economic and exergetic optimization of a municipal solid waste incineration plant for sustainable power generation

Simultaneous economic and exergetic optimization of a Municipal Solid Waste (MSW) incineration power generation plant is performed in this research for reaching the higher power production, lower payback period and higher exergy efficiency with more stringent environmental protection. To reach these goals, modeling and optimizing of MSW incineration plant were performed by the ASPEN Plus and MATLAB software respectively. The first method named exergo-economic, used a single objective function (the sum of exergy destruction cost rate and total equipment cost rate). The second method used multi-objective optimization with two objective functions (the total equipment cost rate and exergy efficiency). Results of applying the exergo-economic optimizing for a local MSW plant with feeding rate of 30 ton/hr provided a system which increased the power generation for about 0.65% and decreased the payback period for 0.2 year in comparison with that for a single economic optimization method.Results showed that for generating the same power output from MSW plant (10139.5 kW), 44,116,660 m3/year natural gas fuel with 7,824,371 $/year fuel cost was required.Finally, the flue gas cleaning and carbon dioxide removal systems were also modeled for the optimum designed MSW incineration plant.

Cooperative Event-Triggered Fuzzy-Neural Multivariable Control With Multitask Learning for Municipal Solid Waste Incineration Process

Municipal solid waste incineration (MSWI) is an industrial process with multiple mechanism reactions, which has strong coupling and time-varying dynamics. It is extremely difficult to design a feasible multivariable controller for MSWI process due to the complex composition of municipal solid waste and fluctuation of calorific value. To solve these problems, a cooperative event-triggered fuzzy-neural multivariable controller with multi-task learning (CETFNMC-MTL) is proposed to realize the adaptive multivariable control of MSWI process. First, a fuzzy-neural multivariable controller is established to control furnace temperature and oxygen content synchronously. Second, a dynamic self-organizing mechanism based on multi-task learning is designed, which splits and merges neurons by calculating the dynamic time warping distance and cumulative contribution of neurons in the continuous time. Third, a cooperative event-triggered mechanism is introduced to improve controller update efficiency while reducing mechanical wear and computational burden. Then, the stability of parameters learning and structure self-organizing process is analyzed to guarantee the successful application of CETFNMC-MTL. Finally, the effectiveness of the controller is tested with process data from an MSWI plant in Beijing, China. The results show that the proposed CETFNMC-MTL has adaptive learning ability, while reducing energy consumption and improving control accuracy.

Selenium leaching behaviors from MSWI fly ash and its control

A large number of fly ash samples from mechanical grate furnaces at a municipal solid waste incineration (MSWI) plant were examined including Se speciation and content. Se leaching behaviors before and after solidification/stabilization(S/S) treatment were comparatively studied. The results showed that Se in the MSWI fly ash was present mainly in the form of selenite with small amounts of physically adsorbed SeO2(s). Se in the low alkalinity ash (pH ∼ 7) tended to be more leachable than that in the high alkalinity ash (pH ∼ 12). The chelation treatment would further raise the risk of Se leaching into the environment from the low alkalinity ash (pH ∼ 7). Three Fe-containing additives (zero-valent iron (ZVI)、α-Fe2O3 and Fe3O4) were introduced, respectively in attempt to immobilize Se in the low alkalinity MSWI fly ash. A strong positive effect was found with ZVI addition in terms of Se leaching from low alkalinity chelated MSWI ash. Comparatively, iron oxides showed no obvious effect. The adjustment to ash alkalinity (CaO addition) exhibited a comparable effect to ZVI addition, which provided another option to control Se leaching from low alkalinity chelated ash.

A knowledge transfer online stochastic configuration network-based prediction model for furnace temperature in a municipal solid waste incineration process

To alleviate the concept drift of an offline prediction model for the furnace temperature in a municipal solid waste incineration (MSWI) process caused by changes in working conditions, a prediction method for the furnace temperature based on a knowledge transfer online stochastic configuration network is proposed in this work. The proposed method includes offline learning and online learning. First, a stochastic configuration network is utilized to construct the offline furnace temperature prediction model, and a knowledge transfer method is employed to update the model under new operating conditions in the offline learning stage. Then, the updated model is used as the initial state of online modeling. Second, the recursive solution of the model output weights is presented to adapt to the dynamic change in incineration conditions, and a direction forgetting mechanism is utilized to enhance the result of the prediction model for the furnace temperature under nonpersistence of excitation in the online stage. Finally, to further verify the proposed online modeling method, the real historical data of an MSWI plant are utilized to finish the comparative experiments. The experimental results with the other methods show that the proposed prediction method for the furnace temperature presents a smaller error. Hence, the proposed method can reduce the influence of working conditions on the accuracy of furnace temperature prediction models.

Impact and recoverability of metals from waste: a case study on bottom ash from municipal solid waste incineration plants

Impact and recoverability of metals from waste: a case study on bottom ash from municipal solid waste incineration plants

Novel cost-effective oxygen-enriched melting method for MSWI fly ash

ABSTRACT Herein, a novel oxygen-enriched melting process for fly ash, which uses the biogas produced from the leachate of municipal solid waste incineration (MSWI) plants, is proposed to reduce the high cost of conventional fly ash – melting technology. The fly ash composition was estimated via X-ray fluorescence analysis; the six constituent elements detected in fly ash in the decreasing order of their content were calcium, chlorine, silicon, sulfur, sodium, and potassium. Based on literature and actual production data, the average yield of the leachate was 15% of the total waste entering the MSWI plants and the COD of leachate was 30,000–75,000 mg/L. The amount of biogas that can be used per ton of fly ash was calculated to be 62.0–157.0 m3. The analysis of melting thermal equilibrium revealed the amount of biogas required per ton of fly ash as 57.8 m3. The aforementioned research findings indicate that the biogas produced by MSWI plants can successfully meet the demands of the oxygen-enriched melting of fly ash produced in these plants. By establishing an oxygen-enriched-melting pilot platform, the pilot tests of melting were conducted on fly ash; the results revealed the good melting effects of fly ash. The X-ray diffraction analysis of the slag demonstrated that the content of the vitreous body met the technical requirements for glassy substances. Furthermore, the leaching toxicity test results revealed that heavy metals were well solidified in the slag. This study presents a novel fly ash – melting scheme for MSWI fly ash, namely, biogas oxygen-enriched melting strategy, which has the advantages of technical feasibility and cost-effectiveness. The proposed technique exhibits considerable prospects for widespread application in MSWI plants in China and can play an important role in the safe disposal of fly ash. Implications: In this paper, a low-cost melting method of municipal solid waste incineration(MSWI) fly ash is proposed. This method uses the biogas generated by MSWI plant itself as fuel for melting. Through research, it has been found that the production of biogas can meet the demand for fly ash melting. Adopting biogas as a molten fuel can significantly reduce the cost of melting, thereby significantly reducing the cost of fly ash melting. This study established a pilot scale platform for the melting of biogas and conducted pilot scale experiments on fly ash and additives. The experimental results showed that the melting system operated well and achieved the vitrification of fly ash. The leaching test results of the molten slag showed that heavy metals were well solidified in the slag. The research results can be extended to the MSWI plant for application, which can significantly reduce the cost of fly ash melting disposal, and has broad application prospects.

A novel process for the desalination of MSWI fly ash via in-situ leachate concentrate washing and residue solution electrolysis

Desalination of municipal solid waste incineration (MSWI) fly ash is necessary prior to its disposal. Water washing followed by evaporation crystallization for salt extraction is a popular desalination process for MSWI fly ash, while facing large water consumption, high evaporation energy consumption, and difficulties in crystalline NaCl selling. Leachate concentrate is another hazardous waste produced in MSWI plant which is hard to be degraded. In this work, a novel process for the desalination of MSWI fly ash via leachate concentrate washing and residue solution electrolysis was proposed. The effects of liquid-to-solid (L/S) ratio and washing step were discussed. Low-carbon electrolysis strategy for the high-salt washed leachate concentrate was explored. Results showed that leachate concentrate washing displayed the similar desalination performance to water washing and the preferred L/S ratio was 3. The dissolution of Cl in fly ash exceeded 92 % after its twice washing. The desalination capacity of leachate concentrate decreased sharply with increasing using times while its salinity increased steadily. With CO2 injection in a regulating chamber, stable electrolysis of the washed leachate concentrate was achieved. The findings are expected to provide guidance on the treatment of MSWI fly ash, leachate concentrate as well as high-salt wastewater in other fields.

Assessment of Zn, Pb and Cd in Soil around an MSW Incineration Plant: Using Risk Assessment and Multivariate Statistical Techniques

To investigate and evaluate the spatial distribution of Zn, Pb and Cd in the soil around a municipal solid waste incineration plant and its ecological risks, Zn, Pb and Cd were analyzed in soil samples around a municipal solid waste incineration plant in Chengdu, Sichuan Province, China. The results revealed that the average content of Zn and Pb did not exceed the soil environmental quality value for the risk control standard for soil contamination of agricultural land (GB15618-2018), but the average content of Cd in the soil was higher than this standard. Multivariate statistical analysis indicated that Cd was the predominant pollutant and had strong correlations with Zn and Pb. The Cd content was most impacted by human activities, which also explained that this municipal solid waste incineration plant has little effect on Zn, Pb and Cd in the surrounding soil. The geo-accumulation index decreased in the order of Cd &gt; Zn &gt; Pb, and the geo-accumulation index of Cd was greater than 5, indicating that the pollution level for Cd was extremely heavy. The comprehensive potential ecological risk index (RI) of various heavy metals was greater than 1200, And the potential ecological risk level of the study area was high. The contribution rate of Cd to RI was relatively large, and Cd pollution should be paid more attention to.

Analysis and Assessment of the Soil Environment Around a Plateau Municipal Solid Waste Incineration Plant

ABSTRACT To understand the source, distribution and degree of pollution of heavy metals in the soil around a plateau municipal solid waste incineration plant, a municipal solid waste incineration plant in Lhasa was taken as the research object in this study. The soil surrounding the facility was sampled, and the contents of heavy metals, including Cu, Pb, Zn, Cr, Ni, Cd, As, and Hg, in the soil were analyzed. Then, heavy metal pollution and risk assessments were conducted using the geoaccumulation index method, Nemerow index method, and potential ecological risk index method. Additionally, correlation and principal component analysis were used to determine the correlation between heavy metals in the soil and their sources of pollution. The results showed that based on the Nemerow comprehensive pollution index, the soil surrounding the incineration plant generally had a low level of pollution. Through the analysis of individual potential ecological risk indices, it was found that only the heavy metal Cd presented moderate potential risks, while the other seven heavy metals had mild potential risks. The average value of the total potential risk coefficient was 107.31, which was less than 150, indicating that there was a slight potential risk associated with the soil around the incineration plant. There was significant correlation between six heavy metals, namely, Cu, Pb, Zn, Cr, Ni, and Cd, in the soil around the incineration plant. Their pollution sources were similar, and their levels tended to be affected by the incineration plant. However, there was no significant correlation between the heavy metals As and Hg and the other six heavy metals. These two heavy metals had independent sources of pollution but were also influenced by human activities.

A Comprehensively Improved Interval Type-2 Fuzzy Neural Network for NOx Emissions Prediction in MSWI Process

The accurate and timely prediction of nitrogen oxides (NOx) emissions ensures eco-friendly and efficient operations for municipal solid waste incineration (MSWI) plants. Due to the high nonlinearity and uncertainty in MSWI processes, constructing an efficient prediction model remains challenging. This work proposes a comprehensively improved interval type-2 fuzzy neural network (CI-IT2FNN) for NOx emissions prediction. First, the neighborhood rough set (NRS) is introduced to determine the structure of this fuzzy neural network automatically, including the number of fuzzy rules and their corresponding consequent parameters. Second, an adaptive shape factor is added to the fuzzy membership function to better cope with the uncertainty, which can help to improve the generalization ability of network. Furthermore, to reduce the computational complexity, the Begian-Melek-Mendel (BMM) method is utilized as the defuzzification method in this study. Then, by integrating the linear least square estimation (LSE) and gradient decent (GD), a hierarchical learning algorithm is applied to adjust the network parameters to further enhance the learning efficiency and accuracy. Finally, after being evaluated by a benchmark simulation, the proposed CI-IT2FNN demonstrates its effectiveness and superiority on NOx emissions prediction.

Modular stochastic configuration network based prediction model for NOx emissions in municipal solid waste incineration process

The accurate prediction of the nitrogen oxides (NOx) emissions is extremely important for pollutant control in municipal solid waste incineration (MSWI) process. Modular neural network (MNN) provides a support for predicting NOx emissions to overcome the limitations of a single model in nonlinear processes and different climatic conditions. However, the design of sub model for MNN is a challenge. We propose a method based on MNN and adaptive ensemble stochastic configuration network (m-AESCN) in this work. First, fuzzy C-means algorithm decomposes the task into several sub datasets with similar characteristics, and an evaluation function is used to guarantee the optimal decomposition result. Second, for each sub dataset, an adaptive ensemble stochastic configuration network as the sub model of modular neural network. The optimal output for sub model can be obtained by an adaptive weighting method based on variance. Third, in testing phase, a sub model activation method based on cluster centroid is proposed to select a suitable sub model. Besides, the m-AESCN method is validated by the real data of an MSWI plant and shows considerable performance in two different datasets. And the proposed method is compared with several modeling methods, such as stochastic configuration network, support vector regression, random forest and so on. The experimental results under two datasets prove that the maximum improvements in accuracy of m-AESCN are 39.74% and 31.67%, respectively.

A Non-Manipulated Variable Analysis of Solid-Phase Combustion in the Furnace of Municipal Solid-Waste Incineration Process Based on the Biorthogonal Numerical-Simulation Experiment

The operating conditions of municipal solid waste incineration (MSWI) are influenced by manipulated variables, such as the feed rate, primary air, and grate speed, as well as non-manipulated variables, such as municipal solid waste (MSW) particle size, mixing coefficient, emissivity, moisture content, and the ratio of C to O. Based on the actual data of an MSWI plant in Beijing, a non-manipulated variable single-factor analysis of solid-phase combustion in the furnace was carried out based on the biorthogonal numerical simulation experiment. First, a solid-phase combustion analysis of the MSWI process was performed for non-manipulated variables, with the main non-manipulated variables determined. Then, based on FLIC 2.3c software, the numerical model was established under benchmark operating conditions. Based on the biorthogonal experiment, several groups of numerical model inputs were designed to generate mechanism data in multi-operating conditions. Finally, a multi-condition numerical simulation experiment was used to study solid-phase combustion under different conditions and analyze non-manipulated variables. The simulation results showed that the maximum solid temperature was 1360 K under the benchmark operating condition and ranged from 1120 to 1470 K under five conditions. Large-size particles and large emissivity were beneficial to solid-phase combustion, while high moisture content and a large mixing coefficient weakened combustion. The results provide support for the subsequent optimal control of the whole MSWI process.

Unveiling the occurrence, distribution, removal, and environmental impacts of 65 emerging contaminants in neglected fresh leachate from municipal solid waste incineration plants

Emerging contaminants (ECs) are commonly found in environmental media. Yet leachate from municipal solid waste incineration plants (MSWIPs), which can serve as a reservoir for various contaminants, including ECs, has received little investigation. To address this gap, 65 ECs were analyzed in the fresh leachate and biological effluent from three major MSWIPs in Shanghai. Results indicated that over half (56%) of the 65 ECs were detected in fresh leachate. Different ECs would be removed to varying degrees after biological treatment, including polycyclic aromatic hydrocarbons (PAHs) (65%), polybrominated diphenyl ethers (PBDEs) (51%), phthalate esters (PAEs) (36%), and organophosphorus pesticides (OPPs) (34%). Notably, for tetrabromobisphenol A (TBBPA), a PBDE substitute, only 2% was removed after biological treatment, while polychlorinated biphenyls (PCBs) were effectively removed at 83%. Water solubility and the octanol-water partition coefficient are key factors influencing the distribution and removal of ECs in leachate. the effluent will still contain refractory ECs even after the biological treatment. These residual ECs discharged to sewers can impact wastewater treatment plants or contaminate surface water and groundwater. These findings provide insights into the leachate contamination by ECs, their environmental fate, factors affecting their behavior, and potential environmental impacts.

Three-Dimensional Numerical Modeling and Analysis for the Municipal Solid-Waste Incineration of the Grate Furnace for Particulate-Matter Generation

A 3D numerical model of the municipal solid waste incineration (MSWI) process was constructed based on a grate furnace with a daily processing capacity of 800 tons. Fluent was used for analyzing key factors affecting the concentration and diffusion level of particulate matter (PM). According to the actual MSWI plant working condition, a 3D model of the incinerator and the waste heat boiler has been constructed under benchmarks. Key factors affecting PM generation were determined by combining mechanistic knowledge and experts’ experience. They were the combustion temperature of solid phase municipal solid waste (MSW), the wall’s PM collision mode, and the second baffle length. Subsequently, the process of resolving the 3D numerical model was delineated. Then, a univariate analysis of the aforementioned 3D model was conducted for the three pivotal factors mentioned above. Conclusively, the effect of the important factors on the number of particles at the outflow of the incinerator was analyzed via orthogonal experiments to obtain the optimal combination. PM concentration initially diminished and then rose with the increased combustion temperature of the solid-phase MSW. Furthermore, a noteworthy reduction in PM concentration was observed when the second baffle length was 12.45–12.95 m. The greatest influence on the PM concentration of the outlet was posed by the wall’s PM collision mode, followed by the second baffle length. The appropriate adjustment of the combustion temperature of the solid-phase MSW, selection of wall materials, and design of the second baffle length were beneficial for diminishing PM concentration and ensuring long-term stable operation of the MSWI process. The combinative optimality of the three key factors was acquired via orthogonal experiments, which proved the subsequent optimal control of PM concentration at the outlet.