Experiments and modeling of fixed-bed debarking residue pyrolysis: The effect of fuel bed properties on product yields

This paper presents a study on the fixed-bed pyrolysis of debarking residue obtained from Norway spruce. Analysis is based on the dynamic model of packed bed pyrolysis which was calibrated by determining appropriate reaction rates and enthalpies to match the model predictions with the experimental data. The model comprises mass, energy and momentum equations coupled with a rate equation that describes both the primary and secondary pyrolysis reactions. The experiments used for the model calibration determined the yields of solid, liquid and gaseous pyrolysis products as well as their compositions at three distinct holding temperatures. Subsequently, the dynamic model was used to predict the product yields and to analyze the underlying phenomena controlling the overall pyrolysis reaction in a fixed-bed reactor.Peer reviewe

Clinical outcomes and complications of treatment with supraflex stent in patients with coronary artery disease: One year follow up

Cardiovascular disease is one of the most important causes of morbidity and mortality in the world. Prevention is often a percutaneous coronary intervention. The new generation of stents is the Sirolimus Eluting Stent. The current study was aimed to investigate the clinical outcomes and complications of treatment with supraflex stent during one year follow up in patients with coronary artery disease. This cross-sectional study was performed on patients with myocardial ischemia who were candidate for angioplasty between 2017 -2018 in Imam Reza Hospital, Mashhad, Iran. Patients were followed for four primary end points including Target lesion revascularization (TLR), stent thrombosis (ST), myocardium infarction (MI) and cardiac death (CD) for one year. Descriptive data were analyzed by Freidman at a significance level of 0.05. A total of 287 patients were enrolled in the study. There was no TLR, MI, ST and CD records in the one month follow up. Six months follow up demonstrated three TLR patients and three MI patients, but no ST and death were reported. After one year follow up, three cases of CD and four ST cases were found in patients treated with supraflex stent. Based on the Freidman test, the highest rate of TLR was revealed in a six-month follow-up when comparing with onemonth and twelve-month follow-up (p = 0.05). No significant relationship was found between the other cases. The most common complications associated with supraflex stent were TLR and MI in six-month follow-up. The most likely occurrence of CD and ST were found in one year follow up

CO₂ gasification of bio-char derived from conventional and microwave pyrolysis

Thermal-chemical processing of biomass is expected to provide renewable and clean energy and fuels in the future. Due to the nature of endothermic reactions, microwave and conventional heating have been applied to this technology. However, more studies need to be carried out to clarify the difference between these two heating technologies. In this work, we investigated two bio-char samples produced from conventional pyrolysis of wood biomass (yield of bio-char: 38.48 and 59.70 wt.%, respectively) and one bio-char produced from microwave pyrolysis with a yield of 45.16 wt.% from the same biomass sample at different process conditions. Various methodologies have been used to characterise the bio-chars. CO₂ gasification of bio-char has also been studied using a thermogravimetric analyser (TGA) and a fixed-bed reaction system. The results show that volatile and carbon contents of the bio-char derived from microwave pyrolysis were between the two conventional bio-chars. However, the microwave bio-char is more reactive for CO₂ gasification, as more CO was released during TGA experiments, and the CO release peak was narrower compared with the CO₂ gasification of the conventional bio-chars. It is suggested that the conventional bio-char is less reactive due to the presence of more secondary chars which are produced from secondary reactions of volatiles during the conventional biomass pyrolysis. While the microwave pyrolysis generates more uniform bio-chars with less secondary char, and therefore, has advantages of producing bio-char for downstream char gasification

Optimization study of incineration in a incinerator with a vertical radiation shaft.

An extensive series of experimental tests were carried out at the Sheffield municipal solid waste incinerator plant (30 MW) from September 1988 to July 1989 to investigate the influence of the design and operating parameters on the performance of the incinerator which burns domestic and commercial wastes (500 ton/day). The following measurements were made around the plant: temperature measurements, pressure measurements, flue gas composition analysis and determination of physical and chemical properties of Sheffield refuse. Several other miscellaneous measurements were also made to monitor the effect of variation of operating parameters on the performance characteristics of the incinerator. A combustion model of Essenhigh type was then employed to model the combustion processes inside the solid refuse bed on top of the travelling grate. In addition a mathematical model of the finite difference type (FLUENT) was used to predict the three dimensional reacting flows (gaseous phase) within the incinerator geometry. Experimental measurements of gas composition, temperature and exit velocity were compared with model predictions. Modelling results were generally in good agreement with measurements. As a result of the test data and the mathematical modelling of the whole process, suggestions for design improvements for the Sheffield municipal solid waste incinerator were made which will substantially increase the efficiency, reduce emissions of pollutants and reduce the maintenance costs at the plant. These are: a) replacing the existing secondary air system with secondary air nozzles and the use of more secondary air (up to 20 % of total air) in order to generate turbulence in the high intensity combustion zone where it is most needed and b) introducing a baffle into the main stream inside the radiation shaft in order to lower the gas temperatures entering the precipitator and to remove the existing recirculation zone in the shaft

Experiments and modeling of fixed-bed debarking residue pyrolysis

This paper presents a study on the fixed-bed pyrolysis of debarking residue obtained from Norway spruce. Analysis is based on the dynamic model of packed bed pyrolysis which was calibrated by determining appropriate reaction rates and enthalpies to match the model predictions with the experimental data. The model comprises mass, energy and momentum equations coupled with a rate equation that describes both the primary and secondary pyrolysis reactions. The experiments used for the model calibration determined the yields of solid, liquid and gaseous pyrolysis products as well as their compositions at three distinct holding temperatures. Subsequently, the dynamic model was used to predict the product yields and to analyze the underlying phenomena controlling the overall pyrolysis reaction in a fixed-bed reactor. (C) 2015 Elsevier Ltd. All rights reserved.Peer reviewe

Development of a Liquid Metal Based Fuel Gas Scrubbing System

The objective of this research project is to perform studies on an analogous room temperature packed bed scrubber operating under non-wetting conditions, providing insight and understanding towards the development of a high temperature packed bed gas scrubber irrigated by molten tin

A study on the combustion dynamics of a biomass fuel bed in a BioGrate boiler

The main objective of this research was to study fuel bed combustion dynamics of a BioGrate boiler with a mechanistic model. First, the fuel specific pyrolysis reaction rates were experimentally determined for the model. Second, the model was validated and finally, it was used to investigate the effects of the primary air flows on drying, pyrolysis and char consumption rates occurring inside the fuel bed. The research results are presented and the role of the dynamic behaviour of the reactions on improving the efficiency of the biomass combustion process discussed.Peer reviewe

Predicting risk of the fall among aged adult residents of a nursing home

Background Fall is one of the most important outcomes of geriatric medicine. The European Assessment System (EASY) Care Standard provides a tool for assessing the risk of the falls. We aimed to evaluate the validity of the Easy-Care risk of the falls (ECRF) sub-score among the residents of a large nursing home. Method A longitudinal study was conducted within a maximum of 34 months following up for falling in Kahrizak Charity Foundation. At the baseline the demographic, mental status and the depression data of 194 subjects aged ≥60 was collected. The Easy-Care standard tools and Performance-Oriented Mobility Assessment (POMA) were also used for data collecting. The time, location, and cause of the falls were recorded immediately after each fall incident. The Correlation between POMA and ECRF scores and the factor analysis of ECRF were considered as the concurrent and construct validity respectively. The Factor affecting the fall occurrence was assessed using the Cox-regression model. Result The mean age of the participants was 76.02 (SD 8.82). Fifty two individuals (27.3%) fell at least once during the mean 756 (SD 187)-day follow up. The Spearman correlation coefficient between ECRF and POMA scores was -0.458 (P < 0.01). Three components were detected in the factor analysis of the ECRF. In the univariate Cox-regression model, the hazard ratio was 1.04 (CI: 1.00–1.07) for each score increase of the ECRF. For the six-month follow-up, at the ECRF cut-off point two of eight, the sensitivity and specificity were calculated as 85.7% and 64.5% respectively. Conclusion It seems that the ECRF is a valid tool for predicting the next 6 months’ fall incidents in older adults