Fluidized Bed Incinerator Research Articles

Enhancing the phosphorus bioavailability of thermally converted sewage sludge by phosphate-solubilising fungi

Biochars and ashes from sewage sludge have a high phosphorus (P) content, but plant P availability is typically rather low. Phosphate-solubilising microorganisms (PSM) have been shown to have the ability to solubilise P from different compounds. The aim of this study was to explore the P-solubilisation potential of different PSM on various biochars and ashes, and the effect of the addition of different carbon (C) and nitrogen (N) sources on their P-solubilisation activity. The most promising combination of PSM, thermal residue and nutrients was then tested for its effect on plant growth and P uptake in a pot trial. Six PSM strains (four Penicillium bilaiae (Pb), one Penicillium aculeatum (Pa) and one Aspergillus niger (An)) were tested on two sewage sludge ashes and one biochar. Pb.4 and An showed the highest P-solubilisation rates on fluid-bed incineration (FB-I) ash. Pb.4 solubilised higher amounts of P when it was supplied with fructose in combination with NH4-N, while An performed equally well with fructose, maltose, mannose and xylose in combination with NH4-N. Increasing the concentration of the C source generally also increased the P solubilisation. However, when FB-I ash was inoculated with Pb.4 plus xylose/NH4-N and applied to spring wheat in a pot trial with γ-irradiated soil, the inoculation did not significantly affect plant shoot biomass or P uptake. The results indicate that the amount and temporal availability of P solubilised by the fungal strain from the ash did not match plant requirements, suggesting that further work is required that focuses on further increasing solubilisation efficiency.

Reuse of bottom ash and fly ash from mechanical-bed and fluidized-bed municipal incinerators in manufacturing lightweight aggregates

This study involved the reuse of residues, including fly ash (FA) and bottom ash (BA), from municipal solid waste (MSW) incineration and reservoir sediment (RS) to make lightweight aggregates (LWAs) and to evaluate the effects of the incinerator type, material mixing ratio, and preparation conditions on the properties of the resulting aggregates. The MSW incineration ashes were mixed in three different ratios (65% BA + 15% FA, 70% BA + 10% FA, and 75% BA + 5% FA) with reservoir sediment and were sintered at temperatures of 950–1050 °C. The ash samples were obtained from an incineration plant equipped with fluidized-bed (FB) and mechanical-bed (MB) furnaces. The ash from the FB incinerator could be turned into LWAs at a relatively low temperature (1000 °C). Compressive strength measurements indicated that these aggregates were stronger than those manufactured using the ash from the MB incinerator. The BA and FA from the FB incinerator showed good chemical stabilities due to the operating conditions of the incinerator, suggesting that they are suitable for fabricating LWAs. Thus, the thermal synthesis of LWAs from mixtures of incineration residue and RS is a highly effective method for the recycling/disposal of MSW incinerator ash.

Influence of Air Pollution Control (APC) Systems and Furnace Type on the Characteristics of APC Residues from Municipal Solid Waste Incinerators

The characteristics of air pollution control (APC) residues are influenced by the furnace type, APC system, and waste composition. In this study, the characteristics of APC residues from nine municipal solid waste incineration plants (the compositions of incinerated solid waste are similar) with different furnace types and APC systems were compared.APC residues contain a great amount of Ca and Cl, and the contents of Al, Si, and Fe in the APC residues from fluidized bed incinerators are higher. The mineral compositions of APC residues are not influenced by the flue gas treatment process, but their contents vary. The contents of Cd, Pb, and Zn in the APC residues from fluidized bed incinerators are lower, while those of Cr, Ba, Cu, and Ni are greatly influenced by the APC systems, with the "grate+dry scrubber" APC residues having the lowest values. The differences in the heavy metal contents in the APC residues from two incinerators before and after the upgrading of the APC systems are not significant. The leaching toxicity of Pb in the APC residues from grate incinerators is higher than that from fluidized bed incinerators, while some elements with low contents in fluidized bed APC residues can be leached more in acetic acid buffer solution. The acid neutralization capacity of the APC residues is related to Ca content. The leaching concentrations of most heavy metals are significantly increased under strong acidity (Cd, Ni, and Zn:leachate pH < 8; Pb, Cu, and Cr:leachate pH < 4). The maximum leaching concentrations of As, Ba, Cu, Ni, and Pb in the APC residues from grate incinerators are mainly controlled by their total content. The leaching concentrations of As, Ba, Cu, Ni, and Pb in the APC residues from fluidized bed incinerators are lower than those from grate incinerators with similar metal contents, which may be due to their different chemical speciation influenced by furnace types and the complexation with Al and Fe compounds.

Seizing the Opportunity for Improved Energy Efficiency of an Existing Fluid Bed Incinerator

Seizing the Opportunity for Improved Energy Efficiency of an Existing Fluid Bed Incinerator

Stabilization of heavy metals in fly ashes from municipal solid waste incineration via wet milling

This study reports the stabilization of toxic heavy metals in fly ashes from incineration of municipal solid waste (MSW) in a grate furnace incinerator (GFI) and a fluidized bed incinerator (FBI) using wet milling without water-extraction pretreatment. After wet milling for 24 h, the relative leaching rates (RLRs) were decreased for all the studied heavy metals (Cr, Cu, Zn, Cd and Pb) and met the regulatory leaching concentrations as determined by Toxicity Characteristic Leaching Procedure (TCLP). For the GFI fly ash, the RLRs of Cr, Cu, Zn and Pb decreased from 11.00%, 4.27%, 5.12%, and 72.64% to 0.81%, 0.08%, 0.33%, and 1.12%, respectively. The decreased rate of RLRs for all four heavy metals had exceeded 90%. For the FBI fly ash, the RLRs of Cr, Cu, Zn, Cd and Pb decreased from 6.81%, 0.09%, 1.99%, 8.92%, and 0.10% to 1.51%, 0.05%, 1.14%, 3.05% and 0.02%, respectively. European Community Bureau of Reference (BCR) sequential extraction results demonstrate that, for the GFI fly ash, wet milling led to decreases in the water- and acid-soluble and reducible fractions, but an increase in the more stable residual fraction. For the FBI fly ash, except for Cu, the residual fraction increased while the water- and acid-soluble fraction largely decreased after wet milling.

Performance evaluation of circulating fluidized bed incineration of municipal solid waste by multivariate outlier detection in China

This first nationwide survey was conducted to evaluate the overall performance of the circulating fluidized bed (CFB) incineration of municipal solid waste (MSW) in 2014-2015 in China. Total 23 CFB incineration power plants were evaluated. The data for monthly average flue gas emission of particles, CO, NO x , SO2 and HCl were collected over 12 consecutive months. The data were analyzed to assess the overall performance of CFB incineration by applying the Mahalanobis distance as a multivariate outlier detection method. Although the flue gas emission parameters had met the Chinese national emission standards, there were 11 total outliers (abnormal behavior) detected in 6 out of 23 CFB incineration power plants from the perspective of the MSWincineration performance. The results demonstrate that it is more important for a better performance of CFBs to reduce the frequencies of the MSW load changes, rather than the magnitudes of the MSW load changes, particularly reducing the frequencies in the range of 10% and more of the load changes, under the same and stable conditions. Furthermore, the overloading occurs more often than the underloading during the operation of the CFB incineration power plants in China. The frequent overloading is 0% to 30% of the designed capacity. To achieve the stable performance of CFBs in practice, an appropriately designed MSW storage capacity is suggested to build in a plant to buffer and reduce the frequency of the load changes.

高効率熱回収型ごみ焼却炉における計測制御システム(「21世紀型諸問題と制御工学・応用の接点特集号」)

高効率熱回収型ごみ焼却炉における計測制御システム(「21世紀型諸問題と制御工学・応用の接点特集号」)

Comparison of ANN (MLP), ANFIS, SVM, and RF models for the online classification of heating value of burning municipal solid waste in circulating fluidized bed incinerators

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.

5-5 過給式流動炉実証運転における下水汚泥の排ガス特性((2)燃焼,Session 5 燃焼・熱利用)

5-5 過給式流動炉実証運転における下水汚泥の排ガス特性((2)燃焼,Session 5 燃焼・熱利用)

Towards better environmental performance of wastewater sludge treatment using endpoint approach in LCA methodology.

The aim of this study is to use the life cycle assessment method to measure the environmental performance of the sludge incineration process in a wastewater treatment plant and to propose an alternative that can reduce the environmental impact. To show the damages caused by the treatment processes, the study aimed to use an endpoint approach in evaluating impacts on human health, ecosystem quality, and resources due to the processes. A case study was taken at Bissell Point Wastewater Treatment Plant in Saint Louis, Missouri, U.S. The plant-specific data along with literature data from technical publications were used to build an inventory, and then analyzed the environmental burdens from sludge handling unit in the year 2011. The impact assessment method chosen was ReCipe 2008. The existing scenario (dewatering-multiple hearth incineration-ash to landfill) was evaluated and three alternative scenarios (fluid bed incineration and anaerobic digestion with and without land application) with energy recovery from heat or biogas were proposed and analyzed to find the one with the least environmental impact. The existing scenario shows that the most significant impacts are related to depletion in resources and damage to human health. These impacts mainly came from the operation phase (electricity and fuel consumption and emissions related to combustion). Alternatives showed better performance than the existing scenario. Using ReCipe endpoint methodology, and among the three alternatives tested, the anaerobic digestion had the best overall environmental performance. It is recommended to convert to fluid bed incineration if the concerns were more about human health or to anaerobic digestion if the concerns were more about depletion in resources. The endpoint approach may simplify the outcomes of this study as follows: if the plant is converted to fluid bed incineration, it could prevent an average of 43.2 DALYs in human life, save 0.059 species in the area from extinction, and make a 62% reduction in the plant’s current expenses needed by future generations to extract resources per year. At the same time it may prevent 36.1 DALYs in humans, save 0.157 species, and make a 101% reduction in current expenses on resources per year, if converting to anaerobic digestion.

Simultaneous removal of SO2 and PAHs by adding calcium-based additives during sewage sludge incineration in a fluidized bed incinerator

In this paper, the simultaneous removal of sulfur dioxide (SO2) and polycyclic aromatic hydrocarbons (PAHs) by adding calcium-based additives [CaO, Ca(OH)2, and CaCO3] during sewage sludge incineration was investigated in a fluidized bed incinerator. The effects of the types, CaO/S (mole ratio) and particle size of calcium-based additives on PAHs or PAHs Toxic Equivalent Quantity concentrations (TEQs) were also considered. The experimental results indicated that CaO had a better performance of reducing SO2 and PAHs emission, and the removal efficiencies of SO2, PAHs and PAHs TEQs at 850 °C were 86.89, 38.88 and 75.19%, respectively. Meanwhile, the increase of CaO/S and decrease of particle size were beneficial for suppressing PAHs formation and capturing SO2. Moreover, the adsorption and catalytic effect of calcium-based additives were regarded as inhibiting PAHs formation.

Distribution Characteristics of Heavy Metals in Different Size Fly Ash from a Sewage Sludge Circulating Fluidized Bed Incinerator

Fly ash samples were collected from a sewage sludge incineration power plant in Zhejiang Province, China, where household sludge was mixed with industrial sludge in a ratio of 1:1. A dry-type centrifugal air classifier was used to separate and obtain particles with different sizes. According to the different air flow rates, five size fractions were obtained. The total size distribution of fly ash is described in this paper, and the chemical composition, mineralogical phase, and microstructure of the five fractions of fly ash were detected using X-ray fluorescence spectrometry, X-ray diffractometry, and scanning electron microscopy with energy-dispersive X-ray spectrometry, respectively. The heavy metal content and speciation with various particle sizes were analyzed using a sequential chemical extraction procedure. An integrated evaluation method that considers the type, content, toxicity, and stability of heavy metals was used to evaluate pollutants of the different particle size segments. An attempt was...

An emergy-LCA analysis of municipal solid waste management

Waste management is a specific practice aimed at reducing the effects of waste materials on the environment and increasing material and energy recovery. The Beijing Municipal Solid Waste Collection and Treatment System has been slow to adopt new technologies capable to enable better treatment results. The aim of the present ecological-economic evaluation of different treatment technologies is to achieve the maximum practical benefits from investments and to ensure the minimum environmental impacts of waste flows based on variable source-separated collection and transportation rates. This paper compared four garbage treatment systems, including separate collection and transportation, sanitary landfills systems, fluidized bed incineration system, and the composting system in Beijing. Results show that as far as the Source Separation Rate (SSR) increased, the yield of recycled materials and sorted waste also rose. High SSR and Separated Transportation Rate (STR) could make recycling more beneficial: however, if more than one approach is applied, it is possible to organize the different steps in a way that minimizes costs and losses. A joint emergy-LCA method is applied in this study to assess the environmental impact of input and output flows and suggest process improvement. The integration offers a way to quantitatively and qualitatively assess costs and benefits, for aware and sound MSW management.

Characterization of Bottom and Fly Ashes Generated Co-incineration of Biomass with Automotive Shredder Residue

One of the viable techniques to reduce land filling of automotive shredder residue is by co-incinerating them with biomass. This study focuses on characterization of bottom and fly ashes produced from the coincineration of the automotive shredded residue with oil palm biomass. The co-incineration was carried out in a pilot-scale fluidized bed incinerator. The oil palm biomass used was oil palm shell while the automotive shredded residue was obtained from a local recycling company. The characterization was done based on particle size distribution, morphology (SEM analysis) and chemical composition (EDS analysis). In term of chemical composition the ashes contain C (Carbon), O (Oxygen), Si (Silicon), K (Potassium), Ca (Calcium) and Fe (Ferum.

Evonik to commission additional R&D operations at its Marl site

In Vienna approximately 1 million tons of waste is incinerated annually. Therefore 13 lines of waste incineration, including fluidized bed incinerators, rotary kilns and grate furnaces, are in operation. Beside municipal solid waste, hazardous waste as well as communal sewage sludge are utilized. All incinerator lines use a wet flue gas cleaning system. Based on the zinc, lead and copper concentrations in its solid residues and knowledge on the mass flow of the residues, a detailed material flow analysis is carried out, that determines the total throughput of these metals. It turns out that 800 t of zinc, 300 t of lead and 550 t of copper pass through Vienna's waste incineration cluster annually. Approximately half of the zinc can be found in the fly ashes of the waste incinerators investigated. In Switzerland a process that recovers pure zinc (> 99.99%) as well as a mixed fraction of lead, copper, zinc and cadmium out of waste incineration fly ash, has been realized at full scale. A comparison between the expected operational costs, on the one hand, and the anticipated revenues from recovered metals and reduced disposal costs resulting from the application of this technology to the investigated waste incinerators, on the other, is discussed within this work. Main drivers responsible for the economical non-applicability to Vienna, are examined.

Potential recovery of phosphorus during the fluidized bed incineration of sewage sludge

Phosphorus is a limited non-renewable resource that is indispensable as an essential nutrient for the growth of organisms in most ecosystems. To demonstrate the reuse of phosphorus resources from sewage sludge ash (SSA), experiments were conducted in a pilot circulating fluidized bed kiln. The experimental results demonstrated that high temperature and calcium oxide (CaO) were beneficial for the transformation of non-apatite inorganic phosphorus (NAIP) to apatite phosphorus (AP). Thermogravimetric differential scanning calorimetry analysis was combined with X-ray diffraction measurements to simulate the process of sewage sludge incineration of the crystal phase transition between aluminium phosphate (AlPO4) and CaO, forming stable AP in the temperature range of 675–850 °C. Additionally, 89.29% of the phosphorus was enriched in sewage sludge bottom ash and 5.61% was distributed in fly ash, with AP being the primary component in the fly ash at 850 °C. AP content generally increased with decreasing particle size, whereas NAIP content exhibited the opposite tendency, and became stable when the particle size was less than 37.5 μm.

Evaluation of concrete production with solid residues obtained from fluidized-bed incineration of MSW-derived solid recovered fuel (SRF)

The aim of this work was to evaluate the use of solid residues derived from municipal solid waste-derived solid recovered fuel incinerated in a circulating fluidized-bed boiler for concrete production. The concrete mixtures casted by partially replacing the natural aggregates with bottom ash (27 %) and exhausted sand (13 %), according to the European standards for concrete, may be classified in the C16/20 class. The leaching tests performed on monolithic concrete samples showed that the concentrations measured in the leachates were lower than limit values for waste recovery, with the only exception of nickel for the mixture made with the exhausted sand.

Levels and profiles of dioxins from circulating fluidised bed incineration

Levels and profiles of dioxins from circulating fluidised bed incineration

Levels and profiles of dioxins from circulating fluidised bed incineration

In China, minimising the emissions of polychlorinated dibenzo-pdioxins and dibenzofurans (PCDD/F) from municipal solid waste incineration (MSWI) remains full of challenges. This paper presents a comprehensive diagnosis of formation, destruction and removal of dioxins in MSWI, after finding out their main area of formation and the parameters influencing their level and signature. The PCDD/F loads significantly increase between furnace exit and the entrance of the air pollution control system (APCS), i.e., in the temperature range of 450 to 250°C. In addition, co-combustion of low-calorific municipal solid waste (MSW) with sulphur-containing coal provides pathways to reduce PCDD/F creation by improving combustion conditions, reducing precursors and unburned carbon, and suppressing PCDD/F formation by the SO2 liberated. Adequate activated carbon (AC) feeding systems and adsorption ability of AC are essential for removing dioxins.

Environmental impact assessment of wood ash utilization in forest road construction and maintenance — A field study

The ever increasing use of wood material as fuel for green energy production requires innovative, environmentally safe strategies for recycling of the remaining wood ash. Utilizing wood ash in forest road construction and maintenance to improve mechanical stability has been suggested as a feasible recycling option. To investigate the environmental impact of wood ash application in forest road maintenance, a two-year field experiment was conducted at two Austrian forest sites (Kobernausserwald (KO) (soil pH5.5) and Weyregg (WE) (pH7.7)) differing in their soil chemical properties. Two different ashes, one produced by grate incineration (GA) and the other by fluidized bed incineration in a mixture with 15vol% burnt lime (FBA), were incorporated in repeated road sections at a 15:85% (V/V) ash-to-soil rate. Leaching waters from the road body were collected and analyzed for 32 environmentally relevant parameters over two years. Upon termination of the experiment, sub-road soil samples were collected and analyzed for ash-related changes in soil chemistry. Even though a larger number of parameters was affected by the ash application at the alkaline site (WE), we observed the most pronounced initial increases of pH as well as Al, As, Fe, Mn, Ni, Co, Cu, Mo, and NO2− concentrations in leachates beneath GA-treated road bodies at Kobernausserwald due to the lower soil buffer capacity at this site. Despite the observed effects our results indicate that, when specific requirements are met (i.e. appropriate ash quality, sufficient soil buffer capacity below the road body, and single time-point ash incorporation within several decades), wood ash application in forest road construction is generally environmentally acceptable.