1,721,051 research outputs found
Sustainable energy production using solid materials
No full textThis textbook focuses on sustainable energy production using solid materials. With explanatory tables and figures, case studies, worked-out examples, and up-to-date bibliographies of other works, the book provides an in-depth exploration of the most innovative aspects of the field. Readers of the book will gain critical skills in characterizing and reacting to biomass, including the formation of pollutants, as well as using fluidized bed reactors for heterogeneous processes. The book also explores innovative methods for mitigating the greenhouse effect, reusing ashes as adsorbents or in cement production, and thermochemical solar energy storage. This book will give students, novice researchers, and industry professionals valuable insights and knowledge into the sustainable production of energy using solid materials
Sherwood (Sh) Number in Chemical Engineering Applications—A Brief Review
No full textThis paper reviews a series of cases for which the correct determination of the mass transfer coefficient is decisive for an appropriate design of the system and its operating conditions. The cases are of interest for applications in the energy sector, such as the thermoconversion of a fuel particle, processes in pipes, packed and fluidised beds, and corollary unit operations, such as extraction, absorption, and adsorption. The analysis is carried out by examining the expressions for the determination of the Sherwood number (which contains the mass transfer coefficient), and, when possible, generalised relationships (also in graphic form) have been provided, to offer a useful tool to cognoscenti
Performance assessment of a demonstration-scale biomass gasification power plant using material and energy flow analyses
No full textIn this study, biomass gasification was investigated in a 1.5 MWth bubbling fluidized bed demonstration plant using air or an air/steam mixture as gasifying agent, and olivine as bed material. The gasification tests were performed in autothermal conditions and keeping constant the equivalence ratio at 0.30. The gasification products, such as producer gas, elutriated particles, tar, and contaminant gases were comprehensively charac-terized. Moreover, the performance of the whole gasification plant and that of its specific process units were quantitatively assessed by employing material and energy flow analyses. The results indicated that steam addition improved the producer gas quality by promoting tar and char conversion into permanent gases, thus increasing the producer gas specific yield, even if the lower heating value of the producer gas and cold gas ef-ficiency slightly decreased. Material flow analysis highlighted that the carbon conversion efficiency was mainly affected by the carbon loss due to the solid particles collected by the cyclone, while energy flow analysis revealed that the cold gas efficiency was significantly influenced by the energy the system used to convert the starting biomass into producer gas. The biomass conversion efficiency into electrical energy was about 24 %
A Modeling and Simulation Study to Accommodate Sorbent Sintering in a Ca-Looping System Coupled with a Cement Plant
No full textOne major bottleneck for the commercialization of Ca-looping (CaL) systems as a promising carbon capture and sequestration (CCS) technology is the decay of the CO2 capture capacity of sorbent particles due to sintering during cyclic operation. The main objective of this study is to develop a predictive process simulation of a steady-state CaL system for tail-end CO2 capture from cement plants. To characterize the CaL system, two modeling approaches were developed and integrated into the Aspen Plus process simulator. While the constrained equilibrium modeling approach accounts for the limitations that sorbent sintering and carbonation-calcination equilibrium impose on the overall performance of the system, the active space time approach relates the basic carbonator design to its operating conditions. The CaL simulation predictions of the sorbent carrying capacity and CO2 capture efficiency were validated against literature experimental data over wide ranges of operating conditions. This study is useful for the further commercialization of the CaL system through its seamless integration with other processes
Gasification of Spruce Wood Chips in a 1.5 MWth Fluidised Bed Reactor
No full textProduction of syngas from the gasification of a biomass is attracting attention with an eye to the concepts of circularity, sustainability, and recent needs, triggered by socio-political events, to increase the level of self-sufficiency of energy sources for a given community. This manuscript reports on the gasification of spruce wood chips in a demonstration fluidised bed gasifier (1.5 MWth, height of 5.40 m, internal diameter of 1.2 m), with 0.2–0.4 mm olivine inventory (1000 kg). Gasification was carried out in air, at four different values of equivalence ratio (from 27% to 36%). The bed was fluidised at about 0.6 m/s, and the bed temperature resulted in the range of about 960–1030 °C as a function of the different tests. A mass flow rate of biomass in the range of about 360–480 kg/h (as a function of the different tests) was fed to the fluidised bed gasifier. Syngas lower heating value, specific mass and energetic yield, and chemical composition, were reported along with data on the production of elutriated fines. Moreover, tar compounds were collected, quantified and chemically speciated. The effect of the equivalence ratio on the main process parameter was critically discussed, proposing useful analytical relationships for the prediction of syngas lower heating value, tar mass flow rate and chemical composition
Fluidised bed gasification of biomasses and wastes to produce hydrogen‐rich syn‐gas – a review
No full textThe sustainable fulfilment of world energy demand should be based on the diversification of the energetic portfolio and, at the same time, on the decrease of the use of fossil fuels in favour of renewable energy sources. This perspective review article focuses its attention on a particular source of renewable energy, i.e. biomass. As non-fossil materials of natural origin, biomasses are formed by storing, in the noble and stable form of chemical bonds, solar energy. Gasification has been here chosen as biomass thermoconversion route: general concepts and history, chemical reactions and uses of syn-gas, and the role of tar, are addressed. Fluidised beds are discussed as reactors to carry out biomass gasification, also considering that a new approach based on dual interconnected fluidised bed schemes can realise the concept of sorption-enhanced gasification (to increase H2 productivity). Syn-gas and tar characteristics are presented and, finally, an original case study concerning the fluidised bed gasification of civil and industrial sludges is presented. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI)
Manufacture of artificial aggregate using MSWI bottom ash
No full textThis paper reports the results of an investigation on material recovery by stabilization/solidification of
bottom ash coming from a municipal solid waste incineration plant. Stabilization/solidification was carried
out to produce artificial aggregate in a rotary plate granulator by adding hydraulic binders based on
cement, lime and coal fly ash. Different mixes were tested in which the bottom ash content ranged
between 60% and 90%. To avoid undesirable swelling in hardened products, the ash was previously milled
and then granulated at room temperature. The granules were tested to assess their suitability to be used
as artificial aggregate through the measurement of the following properties: density, water absorption
capacity, compressive strength and heavy metals release upon leaching. It was demonstrated that the
granules can be classified as lightweight aggregate with mechanical strength strongly dependent on
the type of binder. Concrete mixes were prepared with the granulated artificial aggregate and tested
for in-service performance, proving to be suitable for the manufacture of standard concrete blocks in
all the cases investigated
Experimental and Modeling Studies of Sr2+and Cs+Sorption on Cryogels and Comparison to Commercial Adsorbents
No full textIn this work, two cryogels with the key monomers methacrylic acid and 2-acrylamido-2-methyl-1-propansulfonic acid (named AAC and SAC, respectively) with various functional groups were used as adsorbents for the removal of cesium and strontium ions from aqueous solutions. Kinetics, equilibrium, and column studies were carried out including experiments in different water matrices (ultrapure, tap, and river water) and comparison to commercial adsorbents. AAC reached sorption capacity of 362 mg g-1 for Cs+ and 209 mg g-1 for Sr2+, whereas SAC polymer showed maximum removal capacities of 259 and 211 mg g-1 for Cs+ and Sr2+, respectively. The five cycles of adsorption/desorption experiments showed a maximum of 8% loss of effectiveness for both cryogels. Batch kinetics adsorption data were modeled by using a rigorous diffusional model coupled to a novel fractal-like expression for variable surface diffusivity. The model revealed that the surface diffusivity dependence on time is nonmonotonic, with the occurrence of a maximum. Also, both fluid film and intraparticle transport resistances were shown to be important, with the internal one being more influential. The cryogels and two commercial materials (ion-exchange resin and zeolite) were tested for the removal of Cs+ and Sr2+ in ultrapure, tap, and river water; the results showed that the cryogels exhibit competitive effectiveness
Use of fluidized bed combustion wastes for the synthesis of low- energy cements
No full textAmong the low-energy binders, calcium sulphoaluminate cements are worthy of consideration also because a wide range of industrial solid wastes can be utilized in their manufacture. In this paper, it has been proposed the use of mixtures composed by fluidized bed combustion wastes as raw materials for the synthesis of calcium sulphoaluminate cements. Several systems based on two fluidized bed combustion-derived wastes (a sulpho-calcic fly ash and a silico-aluminous fly ash) and a solid waste generated within a traditional coal-fired power plant were heated in a laboratory electric oven for 2 hours at temperatures ranging from 1050°C to 1300°C. Calcium sulphoaluminate was often obtained and its formation was related to the waste nature and the burning temperature
Investigating the behavior of six limestones in presence of steam in dual interconnected fluidized beds, under operating conditions relevant for sorption-enhanced gasification
No full textThis paper presents results on the behavior, in terms of CO2 capture capacity and attrition/fragmentation tendency, for six limestones processed in a dual interconnected fluidized beds system under operating conditions simulating those of sorption-enhanced gasification in presence of water vapor. Ten calcination/carbonation cycles have been carried out for each sorbent; in particular, carbonation has been carried out at two temperature levels (650 °C and 700 °C), with a CO2 and H2O inlet concentration of 10% for both gases. Degree of CaO carbonation (with related modelling) along the cycles, and particle size distribution at the end of the cycles, have been analyzed and discussed, together with results coming from ex situ impact fragmentation tests carried out in a specifically devoted apparatus. The discussion has been extended to particular cases in which the system was operated in the absence of steam, to analyze the role of this species on the sorbent behavior
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