Fluidized Bed Incinerator Research Articles

Continuous, Real Time Analysis Of Firing Rate and Cake Solids From Fluid Bed Incinerator Flue Gas Data

Continuous, Real Time Analysis Of Firing Rate and Cake Solids From Fluid Bed Incinerator Flue Gas Data

Gains in Operating Efficiency Achieved With the Implementation of Continuous, Real-Time Analysis of Firing Rate and Cake Solids from Fluid Bed Incinerator Flue Gas Data

Gains in Operating Efficiency Achieved With the Implementation of Continuous, Real-Time Analysis of Firing Rate and Cake Solids from Fluid Bed Incinerator Flue Gas Data

Trace element partitioning in ashes from boilers firing pure wood or mixtures of solid waste with respect to fuel composition, chlorine content and temperature

Trace element partitioning in solid waste (household waste, industrial waste, waste wood chips and waste mixtures) incineration residues was investigated. Samples of fly ash and bottom ash were collected from six incineration facilities across Sweden including two grate fired and four fluidized bed incinerators, to have a variation in the input fuel composition (from pure biofuel to mixture of waste) and different temperature boiler conditions. As trace element concentrations in the input waste at the same facilities have already been analyzed, the present study focuses on the concentration of trace elements in the waste fuel, their distribution in the incineration residues with respect to chlorine content of waste and combustion temperature.Results indicate that Zn, Cu and Pb are dominating trace elements in the waste fuel. Highly volatile elements mercury and cadmium are mainly found in fly ash in all cases; 2/3 of lead also end up in fly ash while Zn, As and Sb show a large variation in distribution with most of them residing in the fly ash. Lithophilic elements such as copper and chromium are mainly found in bottom ash from grate fired facilities while partition mostly into fly ash from fluidized bed incinerators, especially for plants fuelled by waste wood or ordinary wood chips. There is no specific correlation between input concentration of an element in the waste fuel and fraction partitioned to fly ash. Temperature and chlorine content have significant effects on partitioning characteristics by increasing the formation and vaporization of highly volatile metal chlorides. Zinc and cadmium concentrations in fly ash increase with the incineration temperature.

Integrated drying and incineration of wet sewage sludge in combined bubbling and circulating fluidized bed units

An original integrated drying and incineration technique is proposed to dispose of sewage sludge with moisture content of about 80% in a circulating fluidized bed. This system combines a bubbling fluidized bed dryer with a circulating fluidized bed incinerator. After drying, sewage sludge with moisture less than 20% is transported directly and continuously from the fluidized bed dryer into a circulating fluidized bed incinerator. Pilot plant results showed that integrated drying and incineration is feasible in a unique single system. A 100 t/d Sewage Sludge Incineration Demonstration Project was constructed at the Qige sewage treatment plant in Hangzhou City in China. The operational performance showed that the main operation results conformed to the design values, from which it can be concluded that the scale-up of this technique is deemed both feasible and successful.

Influence of various chlorine additives on the partitioning of heavy metals during low-temperature two-stage fluidized bed incineration

In this study, a pilot-scale low-temperature two-stage fluidized bed incinerator was evaluated for the control of heavy metal emissions using various chlorine (Cl) additives. Artificial waste containing heavy metals was selected to simulate municipal solid waste (MSW). Operating parameters considered included the first-stage combustion temperature, gas velocity, and different kinds of Cl additives. Results showed that the low-temperature two-stage fluidized bed reactor can be an effective system for the treatment of MSW because of its low NOx, CO, HCl, and heavy metal emissions. The NOx and HCl emissions could be decreased by 42% and 70%, respectively. Further, the results showed that heavy metal emissions were reduced by bed material adsorption and filtration in the second stage. Regarding the Cl addition, although the Cl addition would reduce the metal capture in the first-stage sand bed, but those emitted metals could be effectively captured by the filtration of second stage. No matter choose what kind of additive, metal emissions in the low-temperature two-stage system are still lower than in a traditional high-temperature one-stage system. The results also showed that metal emissions depend not only on the combustion temperature but also on the physicochemical properties of the different metal species.

Emission characteristics of PCDD/Fs, PAHs and PCBs during the combustion of sludge-coal water slurry

This study focused on the combustive feasibility of Sludge-coal water slurry (SCWS) in a commercial circulating fluidized bed incinerator, and on the emission characteristics of the inorganic and organic contaminants in the flue gas during the combustion of SCWS. The results showed the flue gases emitted contained nitrogen oxides (NOx), sulfur oxides (SOx), PAHs, PCBs and PCDD/Fs during the combustion of SCWS in different mixture ratio (0%, 10%, 20%, 30%, 40%). When the ratio of sludge increased, the concentration of NOx increased and the concentration of SOx decreased, while no significant changes were found for the other inorganic gases. The ∑PAHs concentration range was from 2.0015 μg/m3 (0%) to 9.7064 μg/m3 (30%), Low molecular weight PAHs (two or three rings) were the main component in flue gases in all proportions. The maximal value of the PCB concentration was 1.7852 μg/m3 (20%), while the minimal value was 0.6191 μg/m3 (0%), all PCBs are mainly low rings. The I-TEQ content of PCDD/Fs increased slightly with increasing of the ratio, but it was still less than that (0.12382 ng/m3) of CSW burning alone. In general, the total PCDD/Fs of 10%–30% ratio does not exceed 0.1 ng/m3 of EU standards. Therefore, the combustion of sludge coal water slurry is feasible, comparing emission of PAHs, PCBs and PCDD/Fs with flue gas emission standards, the best ratio of SCWS is 20%–30%.

Simultaneous removal of sulfur dioxide and polycyclic aromatic hydrocarbons from incineration flue gas using activated carbon fibers

Incineration flue gas contains polycyclic aromatic hydrocarbons (PAHs) and sulfur dioxide (SO2). The effects of SO2 concentration (0, 350, 750, and 1000 ppm), reaction temperature (160, 200, and 280 °C), and the type of activated carbon fibers (ACFs) on the removal of SO2 and PAHs by ACFs were examined in this study. A fluidized bed incinerator was used to simulate practical incineration flue gas. It was found that the presence of SO2 in the incineration flue gas could drastically decrease removal of PAHs because of competitive adsorption. The effect of rise in the reaction temperature from 160 to 280 °C on removal of PAHs was greater than that on SO2 removal at an SO2 concentration of 750 ppm. Among the three ACFs studied, ACF-B, with the highest microporous volume, highest O content, and the tightest structure, was the best adsorbent for removing SO2 and PAHs when these gases coexisted in the incineration flue gas.ImplicationsSimultaneous adsorption of sulfur dioxide (SO2) and polycyclic aromatic hydrocarbons (PAHs) emitted from incineration flue gas onto activated carbon fibers (ACFs) meant to devise a new technique showed that the presence of SO2 in the incineration flue gas leads to a drastic decrease in removal of PAHs because of competitive adsorption. Reaction temperature had a greater influence on PAHs removal than on SO2 removal. ACF-B, with the highest microporous volume, highest O content, and tightest structure among the three studied ACFs, was found to be the best adsorbent for removing SO2 and PAHs.

Characterization of fly ash from a circulating fluidized bed incinerator of municipal solid waste.

Treatment and disposal of fly ash in China are becoming increasingly difficult, since its production has steadily risen and its features are uncertain. The excess pollutant components of fly ash are the key factor affecting its treatment and resource utilization. In this study, fly ash samples collected from a power plant with circulating fluidized incinerators of municipal solid waste (MSW) located in Shandong Province (eastern China) were studied. The results showed that there were no obvious seasonal differences in properties of fly ash. The content of total salt, Zn, and pH exceeded the national standards and low-ring polycyclic aromatic hydrocarbons (PAHs) and polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (Fs) were the main organic components of fly ash for this power plant, which posed great threats to the surrounding environment. The amount of Zn of fly ash was higher than other heavy metals, which should be due to alkaline batteries of MSW. The leachate of fly ash had low concentrations of heavy metals and the main soluble components were sulfates and chlorides. The major mineral crystals of fly ash were SiO2, CaSO4, and Fe2O3. The main organic pollutants were low-ring PAHs, polychlorinated PCDDs, and low-chlorinated PCDFs, and concentrations were lower than the limiting values of the national regulations. Additionally, the distribution of PCDD/Fs had either a positive or a negative linear correlation with fly ash and flue gas, which was associated with the chlorinated degree of PCDD/Fs. The analysis was conducted to fully understand the properties of fly ash and to take appropriate methods for further comprehensive utilization.

210 次世代型流動床式高効率ごみ発電施設技術について : 平塚市「環境事業センター」の運転状況報告(廃棄物発電・バイオマス発電,熱利用技術)

For the Hiratsuka City "Kankyou Jigyo Center (New Environment Management Center)", Ebara has delivered advanced fluidized-bed waste incineration technology by which efficient Energy-from-Waste can be realized. After 11 months commercial operation since October 2013 with 63,000 tons of total waste throughput, it has been revealed that gross thermal efficiency is 19.6% and net thermal efficiency is 13.7% in average. Thanks to high responsivity and controllability of the system, main steam flow rate, generated power or transmitted power can be positively and reliably controlled. As a result, it has been achieved that the transmitted power can be well stabilized within a range of ±3% around its target value with a probability of approx. 94%.

次世代型下水汚泥焼却炉「過給式流動燃焼システム」の実用化

次世代型下水汚泥焼却炉「過給式流動燃焼システム」の実用化

次世代型下水汚泥焼却炉「過給式流動燃焼システム」の実用化

次世代型下水汚泥焼却炉「過給式流動燃焼システム」の実用化

Agglomeration characteristics during fluidized bed combustion of salty wastewater

Fluidized bed combustion is a well-established and widely used technology for treatment of combustible wastewater. However, agglomeration is always encountered in industrial practice when dealing with wastewater that is rich in alkali metals. The objective of this present paper is to illustrate the agglomeration behaviors during fluidized bed incineration of salty wastewater. Various operational parameters were presented, viz. salt content, bed temperature, fluidizing gas velocity, static bed height, bed materials, and different additives. On the basis of SEM/EDX and XRD analysis of agglomerate samples, the mechanisms of agglomerate formation as well as the inhibition mechanisms of agglomeration for different additives were also discussed. The results show that agglomeration is promoted by the increasing of salt content, bed temperature, bed height, particle size, and by the decline of fluidizing gas velocity. All the additives tested, including CaCO3, Al2O3, Fe2O3 and Kaolin, are effective to different extents in inhibiting agglomeration. Physical effects were found to be the main inhibition mechanisms of agglomeration when the bed temperature is below 850°C. Moreover, better results were also observed with increasing of additive amounts.

Control of inhalable particulate lead emission from incinerator using kaolin in two addition modes

Particulate lead emission control by kaolin was performed in a fluidized bed incinerator at 850–1000°C. The inhalable particulate lead was sampled after a cyclone by a low pressureimpactor. The lead capture process is proposed as three steps: 1) after capture the kaolin particle reacts with lead vapor to form PbO·Al2O3·2SiO2, then 2) lead nanoparticles from homogeneous nucleation of lead vapor conglutinate onto the melting surface of kaolin, and 3) simultaneously, fine particles containing lead conglutinate onto coarse kaolin particles. The kaolin was added in two modes: 1) mixing with solid fuel, and 2) injecting with secondary air. Compared with mode one, kaolin injection caused a much higher concentration of kaolin in the flue gas which led to the capture characteristic difference between two modes. The optimum temperature for mode one to achieve the maximum capture efficiency of submicron lead was 950°C. The optimum kaolin addition proportion for mode two to achieve the maximum capture efficiency was 3%. Overall, kaolin injection is a more effective mode to control submicron lead emission over the temperature range from 850°C to 900°C, while kaolin mixed with the fuel is a simple mode and is more effective at 950°C.

On the reliability of reusing bottom ash from municipal solid waste incineration as aggregate in concrete

The present work concerns an experimental investigation on the use of residues derived from fluidized bed incinerators as aggregates for concrete. Concrete mixtures were obtained from conventional mix designs used in the production of unreinforced precast elements by partial replacement of natural aggregates with recycled components. The characterization was performed by means of physical and mechanical tests according to the prescriptions of the Italian technical code for construction, with special attention to the probabilistic evaluation of the compressive strength and an investigation of the tensile behavior of the considered specimens. The simplified statistical analysis shows that mixtures containing recycled aggregates may achieve characteristic values of the compressive strength that are very close to the performance of conventional mix designs that are commonly used in the investigated applications. The average compressive strength and the material reliability, i.e., the scattering of results, of concretes containing recycled aggregates are both comparable with those of the reference concrete. Conversely, an investigation on the tensile strength points out a lower performance for mix designs including recycled aggregates. In both cases, the adoption of 42.5R cement is found to remarkably improve experimental results, i.e., to reduce the gap between the performance of concretes containing recycled aggregates and the reference concrete.

Development of a low-temperature two-stage fluidized bed incinerator for controlling heavy-metal emission in flue gases

This study develops a low-temperature two-stage fluidized bed system for treating municipal solid waste. This new system can decrease the emission of heavy metals, has low construction costs, and can save energy owing to its lower operating temperature. To confirm the treatment efficiency of this system, the combustion efficiency and heavy-metal emission were determined. An artificial waste containing heavy metals (chromium, lead, and cadmium) was used in this study. The tested parameters included first-stage temperature and system gas velocity. Results obtained using a thermogravimetric analyzer with a differential scanning calorimeter indicated that the first-stage temperature should be controlled to at least 400 °C. Although, a large amount of carbon monoxide was emitted after the first stage, it was efficiently consumed in the second. Loss of the ignition values of ash residues were between 0.005% and 0.166%, and they exhibited a negative correlation with temperature and gas velocity. Furthermore, the emission concentration of heavy metals in the two-stage system was lower than that of the traditional one-stage fluidized bed system. The heavy-metal emissions can be decreased by between 16% and 82% using the low-temperature operating process, silica sand adsorption, and the filtration of the secondary stage.

Emergy Evaluation of the Urban Solid Waste Handling in Liaoning Province, China

Waste management is a distinct practice aimed at reducing its effects on health and the environment and increasing energy and material recovery. The urban waste management industry has been slow to adopt new technologies, such as sanitary landfills and incineration, which enable better treatment results. The aim of a thorough ecological-economic evaluation of different treatment technologies is to extract the maximum practical benefits from investments and to ensure the minimum environmental impacts of wastes. This paper compares four garbage treatment systems, including sanitary landfills systems, fluidized bed incineration system, grate type incineration system and the current landfills system in Liaoning Province, China. By considering the economic and environmental impacts of waste treatment and disposal, impact of emissions, and contribution of wastes input, this paper constructed an emergy-based urban solid waste model for evaluating the sustainability of the holistic systems. The results in Liaoning indicate that the human health losses caused by the harmful air emissions are ranked in this order: fluidized bed incineration > grate type incineration > current landfills > sanitary landfills, while the ecosystem losses are ranked: grate type incineration > fluidized bed incineration > sanitary landfills > current landfills. The electricity yield ratios are ranked: grate type incineration > fluidized bed incineration > sanitary landfills > current landfills. Taken together this suggests that in considering the incineration option, decision makers must weigh the benefits of incineration against the significant operating costs, potential environmental impacts, and technical difficulties of operating. Emergy analysis of the urban solid treatment systems can provide a set of useful tools which can be used to compare the comprehensive performances of different waste treatment processes for decision-making and optimizing the whole process.

Evidence of formation of the tridymite form of AlPO4 in some municipal sewage sludge ashes

Evidence is provided that the tridymite component observed in the X-ray diffraction patterns of some sewage sludge ashes (SSAs) should not be interpreted as the tridymite modification of SiO2 but as the tridymite form of AlPO4. This proof is based on a combined X-ray Powder Diffraction (XRD), X-ray fluorescence (XRF) and Mossbauer spectroscopy investigation of two SSAs produced at two fluidized bed incineration facilities, located in different municipalities and operated differently. The structural and chemical characterization was carried out on the ‘as received’ SSA samples as well as on the residues of these two SSAs pretreated by leaching in citric acid. In addition, direct proof is presented that the tridymite form of AlPO4 does crystallize from X-ray amorphous precursors under conditions that mimic the huge heating rate and short retention time (just seconds at T ≈ 850 °C) typical for fluidized bed incinerators.

Incineration of kitchen waste with high nitrogen in vortexing fluidized-bed incinerator and its NO emission characteristics

Some municipal solid waste (MSW) can be used as the fuel. Combustion of MSW with high nitrogen content is successfully conducted in a lab-scale vortexing fluidized-bed incinerator (VFBI). Pigskin with 16.5 wt.% nitrogen content was used to simulate the high nitrogen content kitchen waste, and silica sand was used as the bed material. The effects of operating conditions, such as the bed temperature, freeboard temperature, excess oxygen ratio, and static bed height on the CO and NO concentrations at the exit of combustor and cyclone were investigated. The experimental results show that the freeboard temperature is the most important factor for CO emission. The order of operating conditions impact on the NO emission is: (1) excess oxygen ratio; (2) bed temperature; (3) freeboard temperature; and (4) static bed height. Utilizing cyclone can significantly reduce the CO emission concentration when the CO concentration released from the freeboard is higher than 50 ppm. On the other hand, the cyclone has no significant effect on the NO emission. Despite having high nitrogen content, a low conversion from fuel-N to NO was attained. Compared with other types of combustors, VFBI reduces the CO and NO emission concentrations much better when burning MSW with high nitrogen content.

Comparison of CaO’s effect on the fate of heavy metals during thermal treatment of two typical types of MSWI fly ashes in China

Both grate and fluidized bed incinerators are widely used for MSW incineration in China. CaO addition for removing hazardous emissions from MSWI flue gas changes the characteristics of fly ash and affects the thermal behavior of heavy metals when the ash is reheated. In the present work, two types of MSWI fly ashes, sampled from both grate and fluidized bed incinerators respectively, were thermal treated at 1023–1323K and the fate of heavy metals was observed. The results show that both of the fly ashes were rich in Ca and Ca-compounds were the main alkaline matter which strongly affected the leaching behavior of heavy metals. Ca was mostly in the forms of Ca(OH)2 and CaCO3 in the fly ash from grate incinerator in which nascent fly ash particles were covered by Ca-compounds. In contrast, the content of Ca was lower in the fly ash from fluidized bed incinerator and Ca was mostly in the form of CaSO4. Chemical reactions among Ca-compounds caused particle agglomeration in thermal treated fly ash from grate incinerator, restraining the heavy metals volatilization. In thermal treated fly ash from fluidized bed incinerator, Ca was converted into aluminosilicates especially at 1323K which enhanced heavy metals immobilization, decreasing their volatile fractions as well as leaching concentrations. Particle agglomeration hardly affected the leaching behavior of heavy metals. However, it suppressed the leachable-CaCrO4 formation and lowered Cr leaching concentration.

Pollutant emission characteristics of rice husk combustion in a vortexing fluidized bed incinerator

Rice husk with high volatile content was burned in a pilot scale vortexing fluidized bed incinerator. The fluidized bed incinerator was constructed of 6 mm stainless steel with 0.45 m in diameter and 5 m in height. The emission characteristics of CO, NO, and SO2 were studied. The effects of operating parameters, such as primary air flow rate, secondary air flow rate, and excess air ratio on the pollutant emissions were also investigated. The results show that a large proportion of combustion occurs at the bed surface and the freeboard zone. The SO2 concentration in the flue gas decreases with increasing excess air ratio, while the NOx concentration shows reverse trend. The flow rate of secondary air has a significant impact on the CO emission. For a fixed primary air flowrate, CO emission decreases with the secondary air flowrate. For a fixed excess air ratio, CO emission decreases with the ratio of secondary to primary air flow. The minimum CO emission of 72 ppm is attained at the operating condition of 40% excess air ratio and 0.6 partition air ratio. The NOx and SO2 concentrations in the flue gas at this condition are 159 and 36 ppm, which conform to the EPA regulation of Taiwan.