Determination of Kinetic and Diffusion Parameters Needed to Predict the Behavior of CaO-Based CO2 Sorbent and Sorbent-Catalyst Materials

For about 10 years, this research group has developed and utilized a particle grain model (PGM), to simulate CO2-capture carried out by CaO-based porous particles. Chemical kinetics and diffusion parameters were either taken from literature studies or fixed by fitting experimental sorption data. As recently observed, this procedure was not fully satisfactory and revealed systematic, minor discrepancies between PGM numerical results and experimental data when predicting sorbents behavior during the initial chemically controlled regime of carbonation. This work deals with the experimental determination of kinetic and diffusion parameters, utilized in the PGM, by means of straightforward thermogravimetric analysis (TGA) tests on small samples of materials to be evaluated for CO2 sorption and sorption-enhanced processes. To validate this procedure, the carbonation of two Ni–CaO–mayenite combined sorbent-catalyst materials (CSCMs) was studied in TGA. The experimental data so obtained were used to infer carbona..

Steam Gasification of Lignite in a Bench-Scale Fluidized-Bed Gasifier Using Olivine as Bed Material

The gasification of lignite could be a promising sustainable alternative to combustion, because it causes reduced emissions and allows the production of syngas, which is a versatile gaseous fuel that can be used for cogeneration, Fischer-Tropsch synthesis, or the synthesis of other bio-fuels, such as methanol. For the safe and smooth exploitation of syngas, it is fundamental to have a high quality gas, with a high content of H2 and CO and minimum content of pollutants, such as particulate and tars. In this work, experimental tests on lignite gasification are carried out in a bench-scale fluidized-bed reactor with olivine as bed material, chosen for its catalytic properties that can enhance tar reduction. Some operating parameters were changed throughout the tests, in order to study their influence on the quality of the syngas produced, and pressure fluctuation signals were acquired to evaluate the fluidization quality and diagnose correlated sintering or the agglomeration of bed particles. The e ect of temperature and small air injections in the freeboard were investigated and evaluated in terms of the conversion eciencies, gas composition, and tar produced.The authors kindly acknowledge the financial support of the European Project LIG2LIQ (RFCS-01-2017 GA796585) co-funded by the European Commission managed Research Fund for Coal and Steel (RFCS)

Steam Gasification of Lignite in a Bench-Scale Fluidized-Bed Gasifier Using Olivine as Bed Material

The gasification of lignite could be a promising sustainable alternative to combustion, because it causes reduced emissions and allows the production of syngas, which is a versatile gaseous fuel that can be used for cogeneration, Fischer-Tropsch synthesis, or the synthesis of other bio-fuels, such as methanol. For the safe and smooth exploitation of syngas, it is fundamental to have a high quality gas, with a high content of H₂ and CO and minimum content of pollutants, such as particulate and tars. In this work, experimental tests on lignite gasification are carried out in a bench-scale fluidized-bed reactor with olivine as bed material, chosen for its catalytic properties that can enhance tar reduction. Some operating parameters were changed throughout the tests, in order to study their influence on the quality of the syngas produced, and pressure fluctuation signals were acquired to evaluate the fluidization quality and diagnose correlated sintering or the agglomeration of bed particles. The effect of temperature and small air injections in the freeboard were investigated and evaluated in terms of the conversion efficiencies, gas composition, and tar produced

A Novel Role of Peripheral Corticotropin-Releasing Hormone (CRH) on Dermal Fibroblasts

Corticotropin-releasing hormone, or factor, (CRH or CRF) exerts important biological effects in multiple peripheral tissues via paracrine/autocrine actions. The aim of our study was to assess the effects of endogenous CRH in the biology of mouse and human skin fibroblasts, the primary cell type involved in wound healing. We show expression of CRH and its receptors in primary fibroblasts, and we demonstrate the functionality of fibroblast CRH receptors by induction of cAMP. Fibroblasts genetically deficient in Crh (Crh−/−) had higher proliferation and migration rates and compromised production of IL-6 and TGF-β1 compared to the wildtype (Crh+/+) cells. Human primary cultures of foreskin fibroblasts exposed to the CRF1 antagonist antalarmin recapitulated the findings in the Crh−/− cells, exhibiting altered proliferative and migratory behavior and suppressed production of IL-6. In conclusion, our findings show an important role of fibroblast-expressed CRH in the proliferation, migration, and cytokine production of these cells, processes associated with the skin response to injury. Our data suggest that the immunomodulatory effects of CRH may include an important, albeit not explored yet, role in epidermal tissue remodeling and regeneration and maintenance of tissue homeostasis

Devolatilization of Residual Biomasses for Chemical Looping Gasification in Fluidized Beds Made Up of Oxygen-Carriers

The chemical looping gasification of residual biomasses—operated in fluidized beds composed of oxygen-carriers—may allow the production of biofuels from syngas. This biomass-to-fuel chain can contribute to mitigate climate change, avoiding the accumulation of greenhouse gases in our atmosphere. The ongoing European research project Horizon2020 CLARA (G.A. 817841) investigates wheat-straw-pellets (WSP) and raw-pine-forest-residue (RPR) pellets as feedstocks for chemical looping gasification. This work presents experimental results from devolatilizations of WSP and RPR, in bubbling beds made of three different oxygen-carriers or sand (inert reference), at 700, 800, 900 °C. Devolatilization is a key step of gasification, influencing syngas quality and quantity. Tests were performed at laboratory-scale, by a quartz reactor (fluidizing agent: N2). For each pellet, collected data allowed the quantification of released gases (H2, CO, CO2, CH4, hydrocarbons) and mass balances, to obtain gas yield (ηav), carbon conversion (χavC), H2/CO ratio (λav) and syngas composition. A simplified single-first order-reaction model was adopted to kinetically analyze experimental data. WSP performed as RPR; this is a good indication, considering that RPR is similar to commercial pellets. Temperature is the dominating parameter: at 900 °C, the highest quality and quantity of syngas was obtained (WSP: ηav = 0.035–0.042 molgas gbiomass−1, χavC = 73–83%, λav = 0.8–1.0); RPR: ηav = 0.036–0.041 molgas gbiomass−1, χavC = 67–71%, λav = 0.9–1.0), and oxygen-carries generally performed better than sand. The kinetic analysis suggested that the oxygen-carrier ilmenite ensured the fastest conversion of C and H atoms into gases, at tested conditions

Experimental Study of Absorbent Hygiene Product Devolatilization in a Bubbling Fluidized Bed

This paper aims to investigate the usage of waste from Absorbent Hygienic Products (AHP) as a fuel for gasification or pyrolysis, two attractive routes to obtain valuable products and dispose of this kind of waste. The study experimentally investigated the devolatilization of coarsely shredded materials from diapers, in a laboratory-scale bubbling fluidized bed made of sand, as a representative preparatory step of the above-mentioned thermochemical conversions. Two versions of shredded materials were considered: as-manufactured diapers (AHPam, as a reference), and the cellulosic fraction of sterilized used diapers (AHPus). Results were presented, obtained from physical-chemical characterization of AHPam and AHPus (TGA, CHNS/O, proximate and ultimate analyses, XRF, ICP-AES, SEM-EDS), as well as from their devolatilizations at 500–600–700–800 °C under two different atmospheres (air plus nitrogen, or pure nitrogen as a reference). Generally, temperature influenced syngas composition the most, with better performances under pure nitrogen. At 700–800 °C under pure nitrogen, the highest syngas quality and yield were obtained. For AHPam and AHPus, respectively: (i) H2 equaled 29.5 vol% and 23.7 vol%, while hydrocarbons equaled 14.8 vol% and 7.4 vol% on dry, dilution-free basis; (ii) 53.7 Nl and 46.0 Nl of syngas were produced, per 100 g of fuel. Overall, AHP emerged as an interesting fuel for thermochemical conversions