Incineration Conditions Research Articles

Numerical simulation and intelligent prediction of a 500 t/d municipal solid waste incinerator

After classifying municipal solid waste (MSW), understanding how changes in its characteristics affect the incineration process becomes essential. Optimizing and adjusting operating parameters is crucial to ensure the smooth operation of MSW incinerators. In this study, we developed a three-dimensional numerical simulation model for a 500 t/d MSW incinerator, based on a two-fluid model that accounts for grate motion. We examined the effects of load and moisture on the combustion process. Using the results from the numerical simulation and on-site operational data, we established a machine learning model to predict incinerator conditions based on load, waste particle size, and moisture content. The average relative errors for the training and test sets were approximately 0.33 % and 0.44 %, respectively. Finally, we compared the influence of different operating parameters on flue gas temperature. Our numerical simulation model and intelligent prediction method offer valuable guidance for optimizing existing MSW incinerators and designing new ones.

Influence of operating parameters on the yield of micro-plastics from plastics incineration

Plastics account for a large proportion of domestic waste. However, micro-plastics will be produced after the plastic is incinerated. The purpose of this study is to find out the change rule of micro-plastics produced during incineration under different conditions. Combining micro-FTIR and PCA algorithm is a good tool to identify the micro-plastics. The PE, PP and PVC micro-plastics are distinguished using PCA-FTIR spectra. The results show different incineration conditions significantly affect the output of micro-plastics. The yield of micro-plastics increases with increasing temperature for both PP and PVC. And the yield of micro-plastics decreases with the increase in flow rate. The maximum amount of micro-plastics is produced by PE, which is 6.62 × 103 after 1 g PE incineration. The yield of micro-plastics in the co-incineration of PE and PP, as well as PE and PVC, significantly increased to 1.42 and 1.89 times of the calculated values, respectively. The nano-particles are also observed. The FTIR and EDS results show that the nano-particles are the products of incineration of plastics, including partly CH bond and unburned carbon, tar and 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.

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.

Optimization of Nanoparticle Collection by a Pilot-Scale Spray Scrubber Operated Under Waste Incineration Conditions: Using Box–Behnken Design

Optimization of Nanoparticle Collection by a Pilot-Scale Spray Scrubber Operated Under Waste Incineration Conditions: Using Box–Behnken Design

Incinerability of PFOA and HFPO-DA: Mechanisms, kinetics, and thermal stability ranking

Thermal treatment is currently the only full-scale technology for the destruction of per- and polyfluoroalkyl substances (PFAS) in wastes. However, concerns exist about the emission of incomplete combustion products from incinerators. To address critical knowledge gaps around the incinerability of PFAS, highest-level coupled cluster theory was applied to elucidate the primary thermal destruction pathways, mechanisms, and kinetics for perfluorooctanoic acid (PFOA) and hexafluoropropylene oxide dimer acid (HFPO-DA, sometimes referred to as “GenX”). These PFAS were then ranked based on U.S. EPA's Thermal Stability Index, which ranges from Class 1 for the most thermally stable chemicals to Class 7 for the most thermally labile chemicals. Initial decomposition of both carboxylic acids proceeds through HF elimination at the α-carbon, but for PFOA surprisingly shifts towards C-COOH bond dissociation in the presence of ammonia due to ammonium stabilization of the variational transition state. Branching substantially reduces the required incineration temperatures, while chain length has no impact on perfluoroalkyl carboxylic acid (PFCA) decomposition rates. Bimolecular reactions with secondary species such as counterions and radicals have lower activation barriers than unimolecular decomposition, but their second-order kinetics depend on concentration and thus waste stream composition, which varies in practice. Simulating radical concentrations under typical incineration conditions, the determined free energies of activation suggest an incinerability ranking for linear PFOA in Class 3, for branched PFOA in Class 4, and for HFPO-DA as well as both PFOA and HFPO-DA ammonium salts in Class 5. Collectively, the temperatures needed to destroy 99.99% of PFOA, HFPO-DA, and other PFCAs in 2 seconds gas residence time are well below those of other commonly incinerated organic compounds such as chlorobenzene (Class 1). Ultimately, sufficient supply of radical donors is critical to ensure safe, efficient, and complete destruction of PFAS during thermal treatment.

Assessment on Optimal Level of Reactive Biosilica Affected by Incineration Conditions in Perlis Rice Husk Ash as Supplementary Cementitious Materials in Concrete

Rice husk (RH) is an agricultural waste transformed to produce secondary by-products and is widely accepted as a substitution of cement or concrete mixtures. This paper deals with the optimal level of SiO2 content due to various incineration conditions of rice husk grown in Perlis, Malaysia. RH was burnt in a controlled environment with a targeted temperature of 650, 750 and 850 °C at various incineration period between 1 and 6 h. All the ashes were assessed for visual inspection and physiochemical and mineralogical properties using X-ray fluorescence (XRF) and X-ray diffraction (XRD). From the analysis, a significant amount of SiO2 in the range of 89–93 wt % was successfully obtained with the preferable properties of supplementary cementitious materials: amorphous silica with high reactivity, ultrafine size, and large surface area. Contrary, the burning temperature of 850 °C greater than 4 h incineration period is not advisable to be used as it transformed into a crystalline phase. No obvious color changes were observed for the ashes as the amount oxide compound of K2O causes carbon entrapped in surface melting. To sum up, 650 °C incineration for 1 h shows an optimum result, and the RH is bearable to reduce the negative impact on the environment.

Effects of incineration conditions on dioxins from simulated municipal solid waste incineration

By changing the simulation incineration conditions of municipal solid waste incineration experiment (nickel catalyst, water), analysing the reaction temperature, incineration exhaust gas flow, concentration of exhaust gas composition, the dioxin concentrations, the toxicity of dioxin equivalent of absorbing liquid, and the change of the absorption liquid organic matter concentration, to explore the effect of different combustion conditions on dioxins from simulated municipal solid waste incineration. The results showed that the addition of nickel catalyst and water could promote the conversion of macromolecule organic matter to small molecule organic matter during the incineration process, and effectively inhibited the precursor synthesis of dioxins, the suppression ratio of dioxins were decreased by 80.7% and the total equivalent toxicity of dioxins were decreased by 98%.

Assessment of plutonium inventory management in the french nuclear fleet with the fuel cycle simulator CLASS

The ASTRID French project aimed at designing, building and operating a sodium fast reactor cooled with liquid sodium. One of the goals of the project was to demonstrate the feasibility of the plutonium multi-recycling in a fast spectrum. Commissariat à l’énergie atomique et aux énergies alternatives (CEA - Atomic & Alternative Energies Commission) has recently announced the abandon of the project which involves that no sodium fast reactor project is planned in France. As a consequence, there is a real interest in assessing technical feasibility for alternative plutonium management. In this work, the plutonium multi-recycling in PWR is assessed from fuel cycle simulations performed with the library CLASS developed by CNRS/IN2P3. The technical conditions for plutonium incineration and stabilization are investigated. It is shown that plutonium can be stabilized with 30% of PWR using multi-reprocessed plutonium in MOX fuel, the rest being composed by PWR loaded with UOX. The transuranic (plutonium and minor actinides) stabilization involves a plutonium incineration. For this reason, around 50% of PWR using multi-reprocessed plutonium is required and the nuclear power has to decrease. In this paper, the methodology and the output analysis are described in detail.

Lab-scale characterization of emissions from incineration of halogen- and sulfur-containing nanowastes by use of a tubular furnace

Many solid materials contain nanoparticles to enhance their functionalities. The question of whether they may release nanoparticles at different moments of their life cycle is raised. Lifecycle includes waste management. There is therefore a need to determine the fate of nanoparticles when the materials they are incorporated in are incinerated. The present study aims at shedding light on these issues. In this context, three real-life wastes selected for their specific compositions were combusted in a lab-scale furnace under incineration conditions. The first two wastes contained nanoparticles, namely silica and titanium dioxide. The third waste was purposely nanoparticle free. In addition, the waste containing titanium dioxide did contain chlorine and the nanoparticle-free material was partly made of sulfur. Disposal of halogen and sulfur-containing garbage implies an incineration temperature of 1100 °C. This complex waste composition was seen as an opportunity to assess possible interactions between nanoparticles and hazardous elements such as chlorine and sulfur during the combustion. Most of the analyses were supported by electronic microscopy imaging after having sampled particles in the fumes and in the bottom ashes. Eventually, three mechanistic scenarios were drawn from these experiments. Focus was made on the evolution of the nanostructure. It was observed to be preserved for the first waste. It disappeared both from the aerosol and the residue for the second waste. The third material, though not initially nanostructured, led to the formation of a nanostructure in the aerosol.

Formation of Friedel’s salt in simulated municipal solid waste incineration bottom ash

To recycle incineration bottom ash as a raw material in cement production, it is important to reduce the chlorides in the ash. Due to Friedel’s salt, washing only is insufficient to remove the chlorides. However, limited research has examined the mechanism of Friedel’s salt formation in ash. In particular, the effect of heating in an incinerator has not been reported. In this study, we investigated the formation of Friedel’s salt using reagents. Friedel’s salt was sufficiently formed upon heating at 1350 °C for 24 h and curing for 30 days. Higher temperatures than actual incineration conditions were required to produce pure Friedel’s salt, but a small amount of chlorine was also fixed in samples closer to actual incineration conditions. XRD and TG/DTA showed that the fixed chlorine most likely contained Friedel’s salt analogues. Washing experiments conducted to understand the leachability of chlorides from samples showed that 20–69% of the fixed chlorine did not dissolve during washing. The leaching behavior of the coexisting materials suggested that some of the fixed chlorine was present not in the form of Ca4Al2O6Cl2·10H2O but in chlorides or mixtures of chlorides with Ca and Cl bound at ratios of 1:1–2, which are more easily dissolved.

Stable Operation of Rotary Stoker Furnace for Industrial Waste

Incineration is one of the most common methods for the treatment of industrial waste. Large amounts of bottom ash are buried without being reused. By reducing components such as toxic metals contained in bottom ash under suitable incineration conditions, landfill waste can be reduced, and re-use of bottom ash can be increased. In this study, effects of the air supplied to the bottom of a commercialy used rotary stoker furnace was investigated as the first step to improve incineration conditions. Bottom ash content must be controlled against various types of industrial waste whose content changes from day to day. The characteristics of industrial waste containing typical components were numerically investigated using a combustion simulation program. It was found that if the primary air used for combustion is not preheated, auxiliary fuel is required to burn waste. Preheated primary air increases the drying rate of the input material, and allows burning of waste without auxiliary fuel. At the furnace, components and calorific values of input raw material are controlled by mixing different types of waste together. Preheated primary air enables reduction of bottom ash, reduction of auxiliary fuel consumption, and stabilization of furnace operation.

Inventory of MSWI Fly Ash in Switzerland: Heavy Metal Recovery Potential and Their Properties for Acid Leaching

From the year 2021 on, heavy metals from Swiss municipal solid waste incineration (MSWI) fly ash (FA) must be recovered before landfilling. This is predominantly performed by acid leaching. As a basis for the development of defined recovery rates and for the implementation of the recovery process, the authorities and plant operators need information on the geochemical properties of FA. This study provides extended chemical and mineralogical characterization of all FA produced in 29 MSWI plants in Switzerland. Acid neutralizing capacity (ANC) and metallic aluminum (Al0) were additionally analyzed to estimate the effort for acid leaching. Results show that all FA samples are composed of similar constituents, but their content varies due to differences in waste input and incineration conditions. Based on their geochemical properties, the ashes could be divided into four types describing the leachability: very good (6 FA), good (10 FA), moderate (5 FA), and poor leaching potential (8 FA). Due to the large differences it is suggested that the required recovery rates are adjusted to the leaching potential. The quantity of heavy metals recoverable by acid leaching was estimated to be 2420 t/y Zn, 530 t/y Pb, 66 t/y Cu and 22 t/y Cd.

Critical Review on the Chemical Reaction Pathways Underpinning the Primary Decomposition Behavior of Chlorine-Bearing Compounds under Simulated Municipal Solid Waste Incineration Conditions

Incineration has been proven as one of the most viable and efficient waste-to-energy strategies for the handling of rapidly mounting municipal solid waste (MSW). However, as a generic and key eleme...

Aftertreatment of Carbon Particles Emitted by Diesel Engine Using a Combination of Corona and Dielectric Barrier Discharge

The collection and incineration mechanisms in the particulate matter (PM) aftertreatment technique proposed by the author were investigated. An experiment for actual exhaust gas was performed by sampling 10 NL/min of exhaust gas from the flue gas from a stationary diesel engine generator. The reactor for PM aftertreatment comprised a glass tube with surrounding corona needles that projected negative charges. Various combinations of voltages applied to each of the corona needles and the surface electrodes were compared. The results enhanced the hypothesis that negatively charged PM is attracted by the dielectric surface that is positively charged by positive ions supplied by the electrode on the glass surface. Subsequently, conditions for carbon incineration by nonthermal plasma were investigated using a simulated dielectric barrier discharge electrode and carbon black particles applied to the surface. It was found that the gap length over which the carbon-adhered area and the surface electrode face each other is the key factor for the rate of incineration.

Study on the relationship between waste classification, combustion condition and dioxin emission from waste incineration

Domestic waste in China is mainly collected as a combination of different types of materials. The components are variable and complex, with very different combustion characteristics making it difficult to optimize the burning to reduce pollution. There are still some controversies about the accuracy of using carbon monoxide (CO) emission to characterize waste incineration performance. Here, we investigated the relationship between waste classification, incineration conditions and dioxin emission and concluded that the concentration of CO in flue gas could not be used as the only criterion of combustion efficiency and safety. Considering the close relationship between the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and products of incomplete combustion, the relatively low concentrations of CO are not a reliable indicator that an incinerator equipped with an activated carbon injection system and fabric filter could achieve the national standards for PCDD/F emission. The goal, therefore, is not only to lower the emission of PCDD/Fs and other pollutants through classifying the waste components at the source, but also to reduce the need for the treatment of incinerated waste to protect the environment and to increase the power generation efficiency of municipal solid waste incineration (MSWI) plants. As the demand for waste disposal continues to rapidly increase, the need for a safe waste incineration system with dioxin emission controls makes the classification of waste an indispensable part of future MSWI systems.

Waste incineration of Polytetrafluoroethylene (PTFE) to evaluate potential formation of per- and Poly-Fluorinated Alkyl Substances (PFAS) in flue gas

In recent years, concerns over some per- and polyfluorinated alkyl substances (PFAS) have grown steadily. PFAS are a large group of chemical substances with widely differing properties. While one class of PFAS, fluoropolymers, have been demonstrated to meet the OECD criteria for polymers of low concern during the in use phase of their lifecycle, questions remain regarding waste handling at the end of useful life for products containing fluoropolymers. To show that polytetrafluoroethylene (PTFE) can be almost fully transformed into fluorine (F) (as hydrofluoric acid (HF)) and to study the possible generation of low molecular weight per- and polyfluorinated alkyl substances (PFAS), PTFE combustion under typical waste incineration conditions at the BRENDA (German acronym for “Brennkammer mit Dampfkessel”) pilot plant at Karlsruhe Institute of Technology (KIT) was investigated. Results indicate that, within procedural quantitation limits, no statistically significant evidence was found that the PFAS studied were created during the incineration of PTFE. Therefore, municipal incineration of PTFE using best available technologies (BAT) is not a significant source of the studied PFAS and should be considered an acceptable form of waste treatment.

Limitations of the toxicity characteristic leaching procedure for providing a conservative estimate of landfilled municipal solid waste incineration ash leaching

ABSTRACTLimitations of the toxicity characteristic leaching procedure (TCLP) for simulating pollutant leaching from wastes disposed of in full-scale landfills are well understood in the waste management profession; the TCLP solution has a lower pH and greater organic acid content than typical landfill leachate. The TCLP serves its intended regulatory objective, however, as long as a conservative estimate of leaching is provided. Here, we examine TCLP’s ability to represent worst-case leaching conditions for monofilled municipal solid waste incineration (MSWI) ash. A critical examination of TCLP’s applicability to MSWI ash is especially relevant, as ash management at MSWI facilities often centers on passing TCLP, regardless of environmental risk posed by the ash or its recyclability. Multiple batch leaching tests were conducted on different MSWI ash streams: mixed ash, fly ash, and different size fractions of bottom ash. Batch-test results were compared with leachate simulating MSWI ash monofills. The TCLP did not consistently provide the most conservative estimate of leaching, supporting the need to consider alternative methodologies in future regulatory development.Implications: This paper analyzes the existing hazardous waste regulatory testing requirement for municipal solid waste incinerator (MSWI) ash management to evaluate whether the TCLP serves its intended purpose in providing the most conservative estimate of landfilled MSWI ash. The results will serve as guidance and motivation for policy makers and the regulatory community to reevaluate the TCLP’s application for characterizing MSWI ash leaching in certain disposal scenarios and could promote consideration of alternative testing procedures based upon results of this study. This study serves to promote representative and accurate quantification of leaching risk from MSWI ash.

Thermal decomposition/incineration of nano-enabled coatings and effects of nanofiller/matrix properties and operational conditions on byproduct release dynamics: Potential environmental health implications

Nano-enabled coatings (NECs) are a growing class of nanomaterials used in architectural applications that are likely to be thermally decomposed at their end-of-life via commercial waste incineration or accidental fires in buildings, thereby increasing concern over the potential release of engineered nanomaterials (ENMs) used as nanofillers. This is especially important for NECs as they have a larger surface-to-volume ratio compared to more traditional nano-enabled products (NEPs). In addition, questions remain about effects of nanofiller and NEC matrix properties and incineration operational conditions on NECs' thermal decomposition (TD) behavior and the physicochemical and morphological (PCM) properties of associated byproducts. In this study, the recently developed Integrated Exposure Generation System (INEXS) platform was used to identify important factors governing TD of NECs and assess potential environmental health implications. Findings confirm that nanofiller chemical composition, size and mass loading in the matrix, as well as incineration conditions, influence nanofiller release into the aerosol. Conversely, the morphology, mass-size distribution and the overall elemental and organic carbon content of the released aerosol are primarily governed by the host NEC matrix properties. The remaining residual ash properties are strongly dependent on the physicochemical composition of the nanofiller. Overall, the study highlights important byproduct release dynamics and exposure profiles during TD of NECs and warrants further studies on understanding the synergistic interactions between the released byproducts, their fate and transformations, and their toxicological and environmental health implications.

Development and Characterization of MgO Coatings on 316L Stainless Steel

The present work deals with the development of MgO coatings on ASTM 316L stainless steel using pulsed laser deposition technique employing KrF excimer laser (λ = 248 nm). Two important process variables, namely oxygen partial pressure and substrate temperature, were varied to get uniform coatings. The process parameters were optimized based on the microstructure and uniformity of the coatings, which had the direct bearing on the performance of the coating. Structural, morphological and microstructural characterizations of the coatings were carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy. While XRD studies confirmed the phase purity and the strain associated with the coating and the substrate, SEM studies revealed the microstructural integrity and morphology of the coatings in addition to establishing the chemistry of coatings. Field testing of the coatings for their sodium compatibility, particularly in aggressive conditions of incineration, confirmed the successful performance of the coatings.