The coking and regeneration of Ni/γ-Al2O3 for the cracking of toluene as a tar model compound were investigated. Special attention has been paid on the effect of coke nature, especially filamentous coke, on the regeneration performance. The catalyst was deactivated by cracking toluene at 700 °C for 0.5 h. The deactivated catalyst was then regenerated by calcination in air at 600 °C for 3 h. The cracking–regeneration cycle usage was carried out up to four times. The results showed that the toluene conversion decreased slowly from 28.2% by fresh catalyst to 22.6% by the third regenerated catalyst and then decreased quickly to 16.3% by the fourth regenerated catalyst. The increase of NiO crystal size from 12.8 to 18.0 nm and the decrease of Brunauer–Emmett–Teller (BET) surface area from 97.7 to 86.9 m2/g caused by sintering and remaining coke were the major reasons for the loss of catalytic activity of Ni catalyst after cycle usage. The cycle usage made the deposited coke more graphitized by slightly enhancing the formation of filamentous coke but reduced the total quantity of coke. The existence of filamentous coke required a higher regeneration temperature (600 °C) due to a more graphitized nature than amorphous coke. The formation and the growth of filamentous coke decreased the Ni particle size from 13.0 nm at 10 min to 11.4 nm at 30 min in the fresh cycle and weakened the interaction between metal and support.

•A simplified de-oiling technique was used as pretreatment to prepare AC.•KOH was used as activator and the adding ratio was 4:1.•Produced ACs owned high surface area of 1103 and 3292 m2/g.•The AC featured good adsorption capability and low heavy metal leaching.To convert the hazardous oily sludge into high quality activated carbon for water pollutant adsorption, a new preparing procedure has been proposed in current study by adding a de-oiling step before activation. The pore structure and surface chemistry of produced active carbons (ACs) were characterized by scanning electron microscopy, N2 adsorption-desorption, XRD, FTIR and XPS. Due to the high content of asphaltene, oily sludge is a promising material for activated carbon production. The surface area of the activated carbon prepared with the proposed de-oiling step was 3292 m2/g which was two times higher than that of normally prepared AC. Moreover, by applying the de-oiling step, the methylene blue adsorption capacities significantly increased from 17.8 mL/0.1 g to 64.6 mL/0.1 g reaching that of ACs generated from commercial asphalt. Moreover, the heavy metal leaching values of the ACs prepared were far below that of hazardous materials. Therefore, the oily sludge could be promising raw material for activated carbon production and the de-oiling procedure could improve the quality of ACs significantly.

•Physical and chemical properties of RDF char and BDF char were studied.•Activation energy and reaction heat of combustion and gasification were calculated.•BDF ash showed improved catalytic activity compared to RDF ash.•Catalytic activity became weaker due to the evaporation AAEM species.Two types of waste derived chars were prepared by pyrolyzing at 600 °C biomass derived fuel (BDF) produced from rice straw and refuse derived fuel (RDF) composed of municipal solid waste and sewage sludge. Thermogravimetric analysis and differential scanning calorimetry (TGA-DSC) were used to investigate the non-isothermal combustion and gasification of the two chars. Kinetic study and reaction heat analysis were carried out and the results were compared. The chemical composition, internal structure, surface condition and carbon structure were also characterized to help understand the basic properties of waste derived chars and its relationship with the reactivity. The results showed that the BDF char samples were more porous and active than the RDF char samples. The total surface area of the BDF char samples was 209.7 m2/g and the percent of micropore was over 90%. But the surface area and percent of micropore for the RDF char samples were significantly lower. The relative content of graphitic carbon was 54.4% for the RDF char and 72.5% for the BDF char samples, indicating a more ordered carbon structure of the BDF char. The activation energies under combustion and gasification conditions were 50.1 kJ mol−1 and 137.9 kJ mol−1 for the RDF char, and 36.6 kJ mol−1 and 119.5 kJ mol−1 for the BDF char, respectively, as calculated by Ozawa–Flynn–Wall method. The ash of the BDF char samples showed improved catalytic activity compared to the RDF char samples. However, the catalytic activity was weaker for the gasification process due to the evaporation of AAEM (alkali and alkaline earth metals) species at high temperatures, especially potassium.

•A rapid, cost-effective, and comparative methodology was proposed to evaluate the HVs of burning MSW online.•Models ranked in descending order of performance are ANFIS, RF, SVM, MLP.•A well trained model is capable of characterizing the variation trend of HVs accurately.The heating values, particularly lower heating values of burning municipal solid waste are critically important parameters in operating circulating fluidized bed incineration systems. However, the heating values change widely and frequently, while there is no reliable real-time instrument to measure heating values in the process of incinerating municipal solid waste. A rapid, cost-effective, and comparative methodology was proposed to evaluate the heating values of burning MSW online based on prior knowledge, expert experience, and data-mining techniques. First, selecting the input variables of the model by analyzing the operational mechanism of circulating fluidized bed incinerators, and the corresponding heating value was classified into one of nine fuzzy expressions according to expert advice. Development of prediction models by employing four different nonlinear models was undertaken, including a multilayer perceptron neural network, a support vector machine, an adaptive neuro-fuzzy inference system, and a random forest; a series of optimization schemes were implemented simultaneously in order to improve the performance of each model. Finally, a comprehensive comparison study was carried out to evaluate the performance of the models. Results indicate that the adaptive neuro-fuzzy inference system model outperforms the other three models, with the random forest model performing second-best, and the multilayer perceptron model performing at the worst level. A model with sufficient accuracy would contribute adequately to the control of circulating fluidized bed incinerator operation and provide reliable heating value signals for an automatic combustion control system.

•An innovative three-stage system for co-gasification of MSW with high alkali coal char was developed.•The tar and HCl content in produced gas could be controlled as low as 11.3 mg/Nm3 and 17.6 mg/Nm3, respectively.•The syngas can reach a low heating value (LHV) of 12.2 MJ/Nm3 and yield rate of 1.57 Nm3/kg.•The effects of pyrolysis, reduction temperature and equivalence ratios (ER) have been evaluated experimentally.The commercial scale up of municipal solid waste (MSW) gasification system is restricted by the low quality of the syngas, especially due to the low heating value and high contents of tar and HCl. In this study, an innovative three-stage system for co-gasification of MSW with high alkali coal char was developed. The modeled MSW was pyrolyzed in the first stage and the raw syngas was partially oxidized in the second stage and then reduced with high alkali coal char in the final stage to produce high quality syngas. The effects of temperatures and equivalence ratios (ER) have been evaluated experimentally and the concentration of condensable tar species and HCl was examined carefully. In general, the two key pollutants in produced gas could be controlled as low as 11.3 mg/Nm3 (tar content) and 17.6 mg/Nm3 (HCl content). Meanwhile, the level of H2, CO, CH4 in synthesis gas reach a stable high level of 41.9 vol%, 29.3 vol% and 7.49 vol%, respectively, while the lower heating value (LHV) attains 12.2 MJ/Nm3, meeting the intake-gas conditions for internal combustion engines. The experimental results confirm that the highest pyrolysis temperature leads to the maximum gas yield from oxidation stage (i.e., 0.913 Nm3/kg at 650 °C), to be compared with 0.898 Nm3/kg (550 °C) and 0.747 Nm3/kg (450 °C). The lowest gasification temperature (800 °C) is indicated as most favorable for HCl removal from syngas, linked with the advancement of reversible reactions between HCl and Ca-based compounds. H2, tar and LHV all decrease with rising equivalence ratio. In summary, the high-quality syngas can be produced at a steady yield rate of 1.57 Nm3/kg from three-stage gasifier, due to dichlorination and catalytic tar cracking action of high alkali coal char at a low cost.

•Longer residence time resulted in higher aromatics production in the oil product.•The incorporation of Zn on HZSM-5 enhanced the total aromatic yield in the oil product.•Highest naphthalenes yield (67.5%) was obtained over 3% Zn modified HZSM-5.•The coke deposited on HZSM-5 was slightly reduced by Zn incorporation.As a potential energy resource with high content of crude oil, hydrocarbon recovery from oily sludge has attracted intensive interests. In this paper, a catalytic pyrolysis experiment of oily sludge has been conducted using HZSM-5 and Zn loaded HZSM-5 zeolites in a two-stage tubular fixed-bed reactor to recover aromatics. The physicochemical properties of HZSM-5 zeolites before and after Zn loading were characterized by XRD, FTIR, N2-adsorption and NH3-TPD. The detailed compositions of oil product samples obtained from pyrolysis at differene residence time and over modified HZSM-5 were analyzed by gas chromatography-mass spectrometry (GC–MS). Results showed that the total aromatic hydrocarbons (TAH) yield increased from 48.7% to 92.2% as residence time changed from 1.0 s to 7.6 s, indicating longer contact time led to a much higher aromatics production. However, under 7.6 s, aromatics were more concentrated on polyaromatics with three or more benzene rings. By contrast, 3.8 s was regarded as the optimum residence time for a higher aromatic yield (84.8%) and the highest selectivity (67.4%) of naphthalenes yield. The catalytic effects of Zn modified HZSM-5 were investigated under 1.9 s. The incorporation of 3% Zn enhanced the TAH yield from 58.7% to 81.0%, as well as the naphthalenes yield (from 31.5% to 67.5%). The promotion of dehydrogenation and deoxygenation over Zn modified zeolite was confirmed by a remarkable increase of the H2 and CO2 yield. Coke depositon on the catalysts was further studied by thermogravimetric (TG) and X-ray photoelectron spectroscopy (XPS) analysis. The coke was determined as polyaromatics coke due to the polycondensation reaction over HZSM-5. Moreover, longer residence time promoted the formation of coke while the loading of Zn slightly reduced it.

•The highest tar conversion of 94.9% was achieved by activation and Ni loading.•H2O/CO2 activation created a more porous and hierarchical pore structure of char.•Better dispersion of Ni particles on char gave a more stable catalytic activity.•Raw char should be initially activated before used as catalyst or catalyst support.High catalytic activity biochar from biomass waste by co-processing of H2O/CO2 activation and nickel loading for the conversion of tar model compound (toluene) were prepared. Raw char was produced by pyrolyzing pine wood sawdust at 800 °C for 1 h, then activated by CO2 or H2O (15 vol.% in N2) at 800–900 °C for 20–80 min. The nickel loading amount was 2 mmol/g-char (11.74 wt.%). The catalytic cracking of toluene was carried out in a lab-scale fixed bed reactor at 800 °C with a residence time of 0.13 s. The results showed that activation significantly improved the average toluene conversion from 40.1% by raw char to 93.2% by activated char (H80). High porosity and hierarchical pore structure, more defects in graphene-like carbon structure and oxygen containing groups on the surface (CO) contributed to the higher catalytic activity of activated chars. The nickel loading increased the toluene conversion of raw char (Ni-char) and activated char (Ni-C900) from 40.1 to 80.8% and from 77.7 to 94.9%, respectively, due to the additional supply of active sites. The toluene conversion ratio of Ni-C900 was larger than that of Ni-char due to a more uniform dispersion of nickel on the activated char support. Thus, the raw biochar should be initially activated before used as catalyst or catalyst support to obtain a higher and more stable catalytic activity for tar conversion.

Oily sludge has received increasing attention for its hazardousness as well as its high potential as an energy resource. Previous studies have developed many methods for oil recovery from oily sludge. In this paper, the effect of KOH on improving the quality of oil product from different oily sludge through pyrolysis was studied. Gel permeation chromatography (GPC), rheometer and gas chromatography–mass spectrometry (GC–MS) were applied to characterize the pyrolysis oil products. The product yields along with possible reaction mechanisms and kinetic characteristics were discussed. It was found that the oil yield decreased while the gaseous yield and solid residues increased with the addition of KOH. The GPC results showed that hydrocarbon species in the pyrolysis oil were more pure and the average molecular weight could be reduced by 53% for the used sample when KOH was added, which could be possibly explained by the cracking reaction of heavy oil into light species. The viscosity of the oil product also showed a significant reduction while the heating value increased in the case of adding KOH. Additionally, SARA fractions were extracted from oil to obtain the asphaltenes content and to identify the detailed components of saturated compounds. Results showed that the concentration of asphaltenes was declined by half and more saturate hydrocarbons (such as C14H30 to C17H36) were produced when KOH ratio reached up to 10%. It revealed that quality of oil product was improved in terms of smaller average molecular weight, lower viscosity, higher heating value, less asphaltenes and more straight chain hydrocarbons.

The cracking of model tar species from municipal solid waste gasification using dried sewage sludge char (DSS char) and bottom ash catalyst (BAC) was investigated, and the catalytic performance was compared to that of well-studied calcined dolomite, NiO/γ-Al2O3, and non-catalytic thermal cracking. The effects of the temperature, internal structure, chemical composition, and functional groups on the performance of tar cracking were characterized. The results showed that, when toluene was selected as the model tar species, conversion ratios for all catalysts were over 94% at 950 °C. The cracking efficiency was ordered as NiO/γ-Al2O3 > calcined dolomite > DSS char > BAC > thermal cracking. When the temperature increased from 750 to 850 °C, the conversion ratios for DSS char and BAC increased from 68.8 and 40.1% to 81.5 and 63.2%, respectively. H2 and coke were the major products of toluene cracking, and catalysts promoted the yield of hydrogen. The lower heating value of the product gas followed the same rules of the conversion ratio. Coke deposition from toluene cracking will decrease the Brunauer–Emmett–Teller surface area of the catalysts, inevitably leading to the deactivation.

The catalytic cracking of model tar species (toluene) using sewage sludge char (SSC) was investigated. The effects of typical syngas components from municipal solid waste (MSW) gasification on toluene conversion ratio, cracking product distribution, and characteristics of the SSC catalyst were studied. Deposited coke significantly decreased the Brunauer–Emmett–Teller (BET) surface area from 74.213 to 51.782 m2/g in a N2 atmosphere. CO2 and steam slowed the decrease of the BET surface area. Hydrogen chloride (HCl) showed a negative effect on the pore structure by the formation of low-melting-point chlorides, which melted above 750 °C and blocked the pores. The cracking efficiency in different reaction atmospheres was ordered as CO2/H2O/N2 > H2/CO/H2O/N2 > H2/CO/H2O/HCl/N2 > N2. The conversion ratios were all above 65% at 750 °C, which reached more than 93% at 950 °C. The highest conversion ratio of 97.1% was achieved at 950 °C when CO2 and steam were presented. CO2 and steam significantly increased the tar conversion ratio and enhanced the resistance of deactivation. CO and H2 increased the tar conversion ratio and changed the cracking product distribution mainly by gas-phase reactions. Besides, when 300 ppm of HCl was presented, the toluene conversion ratio decreased from 86 to 81.2% at 850 °C.

•A new U-type gasification-catalysis system is delicately designed.•Operating conditions can greatly affect gasification performance of leather scraps.•Water vapor can increase the yield of hydrogen twice.•The highest hydrogen yield of 74.7 g per kg ISW is obtained for leather residue.•Pore structure of bottom ash is analyzed to evaluate the gasification results.The development of clean and low-cost hydrogen production method is of great research interests and environmental benefits. In this paper, a U-type gasification system which consisted of a downdraft gasifier, a cyclone separator and a catalytic tar cracking bed was delicately designed for producing hydrogen-enriched syngas from artificial leather scrap, typical industrial solid waste (ISW) discharged from shoes and suitcase manufactures. The influences of air/fuel equivalence ratio (ER), gasifying agent, catalyst, and reaction temperature were experimentally studied to achieve the optimal hydrogen yield and carbon conversion rate. Results showed that when saturated air was used as gasifying agent, H2 yield reached a highest value of 74.75 g per kg ISW at ER = 0.3 and further increasing ER would decrease the yield of H2 and deteriorated the syngas quality due to the promoted oxidation reaction and the dilution of N2. Compared with the pure air gasification, the addition of water vapor could significantly enhance the yield of hydrogen from 37.67 g/kg to 74.58 g/kg. Moreover, lower heat value (LHV) of syngas and carbon conversion efficiency increased by 22.5% and 17.9% at the gasification temperature of 700 °C, respectively, when replacing air with air/steam as the gasifying agent. The use of calcined dolomite could not only crack tar species in the syngas into light components efficiently, but also could reduce the concentration of CO2 due to the recarbonation effect of CaO. Higher gasification temperature could promote H2 yield, but the heat value of syngas would decrease. For ISW sample investigated in this study, the highest energy conversion efficiency of 84.4% was obtained at the gasification temperature of 700 °C and the ER of 0.2 when air/steam and calcined dolomite were used as gasifying agent and catalyst.

An innovative tomographic method using tunable diode laser absorption spectroscopy (TDLAS) and algebraic reconstruction technique (ART) is presented in this paper for detecting two-dimensional distribution of H2O concentration and temperature in a premixed flame. The collimated laser beam emitted from a low cost diode laser module was delicately split into 24 sub-beams passing through the flame from different angles and the acquired laser absorption signals were used to retrieve flame temperature and H2O concentration simultaneously. The efficiency of the proposed reconstruction system and the effect of measurement noise were numerically evaluated. The temperature and H2O concentration in flat methane/air premixed flames under three different equivalence ratios were experimentally measured and reconstruction results were compared with model calculations. Numerical assessments indicate that the TDLAS tomographic system is capable for temperature and H2O concentration profiles detecting even the noise strength reaches 3% of absorption signal. Experimental results under different combustion conditions are well demonstrated along the vertical direction and the distribution profiles are in good agreement with model calculation. The proposed method exhibits great potential for 2-D or 3-D combustion diagnostics including non-uniform flames.

Due to the high moisture content (25–65%) dewatering is essential for the clean and efficient utilization of lignite as fuel or feedstock for chemical industry. In order to quantitatively evaluate the desorption energy of contained water content, a prediction model was proposed in this paper based on Lennard-Jones 10-4-3 solid–fluid potential equation and Clausius–Clapeyron principle using lignite pore structure and specific surface area. Based on the proposed model, the drying behavior of two typical Chinese lignite respectively collected from coal mine at Xinjiang and Inner Mongolia districts were experimentally studied and intelligent gravimetric analysis (IGA) was employed for model evaluation. Results show that the water content of original coal sample are 22.4% and 37.6% by weight for Xinjiang and Inner Mongolia lignite, respectively. After air drying at 40 °C, the water content can be dramatically reduced to 13.4% and 17.9%. The overall dewatering energy of the retained moisture after air dying are 38.84 kJ/(100 g air dried coal) for Xinjiang lignite and 53.57 kJ/(100 g air dried coal) for Inner Mongolia lignite. From IGA analysis, it was found that the gradient of the desorption energy of Xinjiang lignite against water content can be separated into three main water desorption stages according to the energy cost.

Heavy metals released from municipal solid waste incinerators have become a major environmental concern. A comprehensive knowledge of metal vapor condensation in fly ash particles during incineration is essential for alleviating heavy metal toxicity, and for optimizing incineration process parameters and flue-gas cleaning systems. In this paper, the condensation of zinc vapor during flue-gas cooling in a 200 t/d fluidized bed incinerator and a 150 t/d moving grate incinerator was characterized and comparatively studied using high resolution synchrotron X-ray absorption spectroscopy (XAS). Principal component analysis, target transformation, and linear combination fitting were employed to identify zinc species directly from size fractionated fly ash particles. The chemical reaction behaviors of different zinc species were described by thermodynamic equilibrium simulations. Consistent with previous theoretical analysis and laboratory scale tests, the condensation behavior of zinc in an industrial incineration system is mainly affected by the sulfur/chlorine ratio and the inorganic particulates. It is found that zinc chloride is the major zinc species in a moving grate incinerator but willemite dominates in the fluidized bed incinerator. The high sulfur and silica/alumina particle concentration in the fluidized bed system changes the condensation propensity of vapors of Zn compounds. Adjusting the concentrations of SO2 in flue-gas can inhibit the formation of zinc chlorides. Silica, alumina, aluminosilicates, and calcium-based compounds are potential sorbents for transforming zinc to less harmful species. To prevent toxic zinc species contained in fine particles from escaping into the atmosphere, wet scrubbers are more suitable for cleaning flue-gases in moving grate incineration systems, while improving the efficiency of dust removal is more important for fluidized bed incineration systems.寻找金属污染物在热转化过程中的生成和迁移规律, 为可燃固体废弃物高效清洁能源化利用提供科学指导。飞灰采自两台不同类型在运行固废焚烧炉; 采样位置位于烟气净化系统之前以规避干扰; 利用同 步辐射技术中的X射线近边吸收结构和吸收精细 结构谱图结合热力学模拟对金属锌的形态进行分 析和研究。1. 金属锌在炉排炉飞灰小颗粒上主要以氯化物形 式存在, 而在流化床飞灰小颗粒上是以铝硅酸盐 为主; 2. 燃烧过程中的高硫氮比能够有效减少锌 有毒形态的生成; 3. 硅、铝和钙基材料是锌蒸汽 有效的吸附剂。

Centrifugation is an efficient and environmentally friendly method to recover valuable oil resources from petroleum sludge. In this paper, the Monte Carlo method was used to predict the settling behavior of different-sized water droplets based on the Navier–Stokes equation. Differential scanning calorimetry (DSC) was used to deduce the size distribution of emulsified water droplets in petroleum sludge. Numerical estimation and experimental analysis both show that the water removal rate increases with a rising centrifugal speed. When the centrifugal speed increased from 2000 to 10 000 rpm, the water removal rate increased from 28 to 99%. Meanwhile, the critical separation size of the emulsified water droplet decreased from over 14 μm at 2000 rpm to around 3 μm at 10 000 rpm. The Monte Carlo method was successfully applied to assess the effect of petroleum viscosity and centrifugal speed on the water removal rate, and the simulations are in good agreement with DSC analysis. The results of this study can provide quantitative information and guidance for optimizing the centrifugation of petroleum sludge for oil recovery.

The surface characteristics of solid particles found in two petroleum sludges were studied, along with their effect on oil recovery. The particles were classified into three types based on their microstructures and settling behavior during centrifugation. Wettability of sludge particles and modified quartz was comparatively investigated by the sessile drop method; solids from petroleum sludge were found to have a contact angle close to that of acidified quartz. When the contact angle decreased from 135.1° to 85.8° and 16.9° in unmodified, acidified, and alkylated quartz, respectively, the oil residue following centrifugation increased from 0.9 to 5.2 and 10.0%. Solids found in petroleum sludge are more hydrophobic than solids from oil sand. Pretreatment methods that can decrease the oil–solids interaction, such as anti-alkylation, will improve oil recovery from petroleum sludge.

Advanced thermal treatment of refuse-derived fuels (RDFs) necessitates accurate determination of the key component fractions and comprehensive understanding of the decomposition characteristics during thermal conversion. In this paper, the linear weighted sum method is employed to retrieve mass fractions of key components in different municipal solid waste (MSW)-derived fuel pellets through thermogravimetric (TG) analysis. A new Gaussian-fitting-based adjusting model is proposed to quantitatively assess the effect of the interaction on the decomposition of individual components based on differential thermogravimetric (DTG) analysis. Results show that the mass fractions of combustible key components can be determined from DTG curves and by applying the Gaussian-fitting-based adjusting model, the effects of the interaction on the decomposition of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), and cellulose can be identified. It is found that, after mixing PE into RDFs, both the reaction time and activation energy of PE are decreased. The degradation of PVC starts at a higher temperature within the temperature range from 200 to 380 °C, and its reaction time is decreased by 50% within the temperature range from 380 to 500 °C. The activation energy of cellulose is slightly increased. The model proposed in this paper could be a promising method to evaluate the interaction between different key components in mixed samples for optimizing the parameters of the thermal conversion system.

When the shape of single wood spheres was captured and processed under different pyrolysis environments instantaneously, the evolution of sample geometry was obtained and a shrinkage model was proposed in this paper. The proposed shrinkage model was coupled with a one-dimensional unsteady wood pyrolysis model to predict the temperature profiles and mass variation as well as product distribution within wood spheres. A one-step drying mechanism and three parallel primary decomposition reactions as well as three secondary cracking reactions were used to describe the entire pyrolysis process. Experiments were carried out to assess the efficiency of the model prediction, and the effects of volume shrinkage on the temperature, weight loss, and product distribution were analyzed and discussed. Experimental results show that the shrinkage rate is proportional to the furnace temperature, and the average shrinkage rate increases from 0.39 to 0.53 mm/min for 20 mm wood spheres and from 0.26 to 0.55 mm/min for 30 mm wood spheres when the furnace temperature increases from 673 to 973 K. However, the final shrinkage ratio is inversely proportional to the furnace temperature and decreases with the increased sphere diameter. The peaks of simulated temperature profiles are in good agreement with experimental results when shrinkage is considered. Simulated mass loss profiles with shrinkage agree well with experimental data. On the contrary, if a constant particle size is used, the deviation between simulated and measured residual fractions is about 24% for the wood spheres studied in this paper.

This study presented a novel diagnosis for the combustion of coal–water slurry (CWS) in a pilot-scale slag-tap vertical cyclone furnace using flame images and three-dimensional temperature distributions reconstructed from these flame images through a two-step inverse radiation analysis. The accuracy of the reconstructed temperature was evaluated by infrared thermometer measurements, with a discrepancy of less than 50 K. The effects of the air/fuel equivalence ratio, the air distribution pattern, and the furnace load on combustion performance were analyzed based on the reconstructed temperature profiles. Experimental and analytical results showed that flame stability was clearly represented by the variance of the image pixel values. The three-dimensional temperature profiles also effectively illustrated the combustion characteristics in the cyclone furnace under different air/fuel settings. By appropriately supplying air, the combustion efficiency of CWS can be maintained at >99% in the proposed cyclone furnace.

A new approach to inverse radiation analysis is presented for non-intrusive 3-D flame temperature reconstruction using flame emission images from four CCD camera detectors installed on the furnace wall. The scattering from participating medium in the flame was considered by combining the discrete radiative transfer method with the discrete ordinate method. A modified minimum residual algorithm was employed to calculate the least squares solution of the ill-conditioned inverse problem. A numerical test problem simulating real temperature measurements in an industrial furnace was used to assess the performance of the proposed method. These assessments indicate that this method is capable of reconstructing 3-D temperature distributions fast and accurately, even with noisy flame emission data. Such a capability has potential in real-time temperature measurement for combustion optimization and pollution emission control.

Temperature is the most important parameter for the improvement of combustion efficiency and the control of pollutants. In order to obtain accurate flame temperatures in a rotary kiln incinerator using non-intrusive thermographic method, the effective flame emissivity was studied. A combined narrow- and wide-band model and Mie scattering method were used to calculate the radiative properties for gases and fly-ash particles under different combustion conditions. The effects of the air/waste ratio and fly-ash particles on the effective flame emissivity were discussed. The results of numerical calculations showed that the effective emissivity decreased from 0.90 to 0.80 when the air/waste ratio increased from 1.0 to 1.8, and the effect of the fly-ash particles was ignorable under the conditions discussed in this paper. Experimental measurement results indicated that the accuracy of the thermographic temperature measurements improved significantly if the setting of the flame emissivity was adjusted according to the air/waste ratio.

•A rapid and cost-effective prediction for the LHV of MSW was developed.•The prediction equation was based on estimated LHVs of wet combustibles in MSW.•The prediction performance of the equation is suitable for practical application.A rapid and cost-effective prediction method based on wet physical composition has been developed to determine the lower heating value (LHV) of municipal solid waste (MSW) for practical applications in China. The heating values (HVs) of clean combustibles were measured in detail, and the effect of combustibles, food waste, and ash content on HV was studied to develop the model. The weighted average HV can be used to predict the MSW HV with high accuracy. Based on the moisture measurements of each major real combustible and the HV of clean solid waste, a predictive model of the LHV of real MSW was developed. To assess the prediction performance, information was collected on 103 MSW samples from 31 major cities in China from 1994 to 2012. Compared with five predictive models based on the wet physical composition from different regions in the world, the predictive result of the developed model is the most accurate. The prediction performance can be improved further if the MSW is sorted better and if more information is collected on the individual moisture contents of the waste.