| 1. |
- Engström, Gunnar, et al.
(author)
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The Swedish CArdioPulmonary BioImage Study : objectives and design
- 2015
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In: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 278:6, s. 645-659
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Journal article (peer-reviewed)abstract
- Cardiopulmonary diseases are major causes of death worldwide, but currently recommended strategies for diagnosis and prevention may be outdated because of recent changes in risk factor patterns. The Swedish CArdioPulmonarybioImage Study (SCAPIS) combines the use of new imaging technologies, advances in large-scale 'omics' and epidemiological analyses to extensively characterize a Swedish cohort of 30 000 men and women aged between 50 and 64 years. The information obtained will be used to improve risk prediction of cardiopulmonary diseases and optimize the ability to study disease mechanisms. A comprehensive pilot study in 1111 individuals, which was completed in 2012, demonstrated the feasibility and financial and ethical consequences of SCAPIS. Recruitment to the national, multicentre study has recently started.
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| 2. |
- Engvall, Christer, et al.
(author)
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Can myocardial strain differentiate hypertrophic from infiltrative etiology of a thickened septum?
- 2011
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In: Echocardiography. - : Wiley. - 0742-2822 .- 1540-8175. ; 28:4, s. 408-415
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Journal article (peer-reviewed)abstract
- Septal systolic strain measurements showed reduced longitudinal function but its localized nature failed to demonstrate radial disturbances in patients with pathologically thickened septum. No difference was found in systolic strain between patients according to the etiology of septal thickness. This limitation might be either technical or is explained by the maintained radial function in all patient groups.
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| 3. |
- Kalm-Stephens, Pia, 1959-, et al.
(author)
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Incidence of asthma between adolescence and adulthood : early risk factors and gender differences
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Journal article (other academic/artistic)abstract
- Background: Several studies have shown gender differences in the prevalence of asthma at various ages. The aim was to investigate the development of respiratory symptoms between adolescence and adulthood in relation to baseline risk factors and gender, and the effect on self-rated health. Methods: In the study Screening project asthma in schools, adolescents aged 12–15 years answered a standardised respiratory questionnaire (ISAAC) and underwent measurements of fractional exhaled nitric oxide (FeNO) and lung function (FEV1) at baseline. Two follow-ups with similar questionnaires were performed after four and 16 years, with 491 subjects participating in all three examinations. Results: The prevalence rates of asthma and wheeze were unchanged after four years, but had increased after 16 years; the increase was significant for females only. A more continuous increase in allergic symptoms showed no gender difference. The adjusted odds ratio [aOR (95% confidence interval)] for the development of asthma was 4.11 (1.27, 13.24) times higher in females with reduced FEV1 and 1.13 (1.06, 1.20) times higher in males with higher FeNO at baseline. Females, but not males, with asthma, rated their health as poor to a higher extent than individuals without asthma at the last follow-up, 20.0% vs. 7.7% (p < 0.01). Conclusions: An increased prevalence of respiratory symptoms was seen primarily between late adolescence and young adulthood, and was significant for females but not males. To optimise health and wellbeing, gender differences in asthma development, associated risk factors, and treatment of respiratory symptoms, must be considered.
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| 4. |
- Liliedahl, Truls, et al.
(author)
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Defluidisation of fluidised beds during gasification of biomass
- 2011
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In: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 35:SUPPL. 1, s. S63-S70
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Journal article (peer-reviewed)abstract
- Defluidisation and agglomeration during fluidised bed gasification of biomass is analysed and discussed. It is argued that the agglomeration and defluidisation processes, in principle, closely resemble those that determine the behaviour of glass during glass processing. Crucial properties for working with glass melts are the viscosity, stickiness, surface tension, etc. It is, however, (very) difficult to theoretically quantify these properties through thermodynamics or other theoretical means. Hence it will be problematic to theoretically predict agglomeration and defluidisation. Models for predicting defluidisation must therefore probably be of an empirical nature. As a consequence of this, a number of fluidised bed gasification tests were empirically analysed with respect to defluidisation. In total 145 tests were evaluated; of these 51 defluidised or exhibited some kind of bed disturbance. A number of fuels and bed materials were included in the analysis using a multivariate statistical approach.Based on the analysis an empirical regression equation for predicting the defluidisation temperature during fluidised bed gasification is suggested.
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| 5. |
- Malinovschi, Andrei, 1978-, et al.
(author)
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Assessment of Global Lung Function Initiative (GLI) reference equations for diffusing capacity in relation to respiratory burden in the Swedish CArdioPulmonary bioImage Study (SCAPIS)
- 2020
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In: European Respiratory Journal. - Lausanne, Switzerland : European Respiratory Society (ERS). - 0903-1936 .- 1399-3003. ; 56:2
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Journal article (peer-reviewed)abstract
- The Global Lung Function Initiative (GLI) has recently published international reference values for diffusing capacity of the lung for carbon monoxide (DLCO). Lower limit of normal (LLN), i.e. the 5th percentile, usually defines impaired DLCO. We examined if the GLI LLN for DLCO differs from the LLN in a Swedish population of healthy, never-smoking individuals and how any such differences affect identification of subjects with respiratory burden.Spirometry, DLCO, chest high-resolution computed tomography (HRCT) and questionnaires were obtained from the first 15 040 participants, aged 50–64 years, of the Swedish CArdioPulmonary bioImage Study (SCAPIS). Both GLI reference values and the lambda-mu-sigma (LMS) method were used to define the LLN in asymptomatic never-smokers without respiratory disease (n=4903, of which 2329 were women).Both the median and LLN for DLCO from SCAPIS were above the median and LLN from the GLI (p<0.05). The prevalence of DLCO DLCO >GLI LLN but DLCO >GLI LLN but versus 4.5%, p<0.001), chronic airflow limitation (8.5% versus 3.9%, p<0.001) and chronic bronchitis (8.3% versus 4.4%, p<0.01) than subjects (n=13 600) with normal DLCO (>GLI LLN and >SCAPIS LLN). No differences were found with regard to physician-diagnosed asthma.The GLI LLN for DLCO is lower than the estimated LLN in healthy, never-smoking, middle-aged Swedish adults. Individuals with DLCO above the GLI LLN but below the SCAPIS LLN had, to a larger extent, an increased respiratory burden. This suggests clinical implications for choosing an adequate LLN for studied populations.
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| 6. |
- Malinovschi, Andrei, 1978-, et al.
(author)
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Consequences of Using Post- or Prebronchodilator Reference Values in Interpreting Spirometry
- 2023
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In: American Journal of Respiratory and Critical Care Medicine. - : American Thoracic Society. - 1073-449X .- 1535-4970. ; 208:4, s. 461-471
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Journal article (peer-reviewed)abstract
- RATIONALE: Post-bronchodilator (BD) spirometry is used for diagnosis of chronic obstructive pulmonary disease (COPD). However, pre-BD reference values are used for spirometry interpretation.OBJECTIVES: To compare the resulting prevalence rates of abnormal spirometry and study the consequences of using pre- or post-BD reference values generated within the Swedish CArdioPulmonary bioImage Study (SCAPIS) when interpreting post-BD spirometry in a general population.METHODS: SCAPIS reference values for post-BD and pre-BD spirometry were based on 10,156 and 1,498 never-smoking, healthy participants, respectively. We studied the associations of abnormal spirometry, defined by using pre- or post-BD reference values, with respiratory burden in the SCAPIS general population (28,851 individuals).MEASUREMENTS AND MAIN RESULTS: Bronchodilation resulted in higher predicted median and lower limit of normal (LLN) for FEV1/FVC ratio. The prevalence of post-BD FEV1/FVC < pre-bronchodilator LLN was 4.8% and that of post-BD FEV1/FVC < post-bronchodilator LLN was 9.9% for the general population. An additional 5.1% was identified as having an abnormal post-BD FEV1/FVC ratio and this group had more respiratory symptoms, emphysema (13.5% vs. 4.1%, p<0.001) and self-reported physician-diagnosed COPD (2.8% vs. 0.5%, p<0.001) than subjects with post-BD FEV1/FVC ratio > LLN for both pre- and post-bronchodilation).CONCLUSIONS: Pre- and post-bronchodilator spirometry reference values differ with regard to FEV1/FVC ratio. Use of post-bronchodilator reference values doubled the population prevalence of airflow obstruction; this was related to a higher respiratory burden. Using post-bronchodilator reference values when interpreting post-bronchodilator spirometry might enable identification of individuals with mild disease and be clinically relevant.
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| 7. |
- Mareschal, Sylvain, et al.
(author)
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Challenging conventional karyotyping by next-generation karyotyping in 281 intensively treated patients with AML
- 2021
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In: Blood Advances. - : American Society of Hematology. - 2473-9529 .- 2473-9537. ; 5:4, s. 1003-1016
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Journal article (peer-reviewed)abstract
- Although copy number alterations (CNAs) and translocations constitute the backbone of the diagnosis and prognostication of acute myeloid leukemia (AML), techniques used for their assessment in routine diagnostics have not been reconsidered for decades. We used a combination of 2 next-generation sequencing-based techniques to challenge the currently recommended conventional cytogenetic analysis (CCA), comparing the approaches in a series of 281 intensively treated patients with AML. Shallow whole-genome sequencing (sWGS) outperformed CCA in detecting European Leukemia Net (ELN)-defining CNAs and showed that CCA overestimated monosomies and suboptimally reported karyotype complexity. Still, the concordance between CCA and sWGS for all ELN CNA-related criteria was 94%. Moreover, using in silico dilution, we showed that 1 million reads per patient would be enough to accurately assess ELN-defining CNAs. Total genomic loss, defined as a total loss 200 Mb by sWGS, was found to be a better marker for genetic complexity and poor prognosis compared with the CCA-based definition of complex karyotype. For fusion detection, the concordance between CCA and whole-transcriptome sequencing (WTS) was 99%. WTS had better sensitivity in identifying inv(16) and KMT2A rearrangements while showing limitations in detecting lowly expressed PML-RARA fusions. Ligation-dependent reverse transcription polymerase chain reaction was used for validation and was shown to be a fast and reliable method for fusion detection. We conclude that a next-generation sequencing-based approach can replace conventional CCA for karyotyping, provided that efforts are made to cover lowly expressed fusion transcripts.
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| 8. |
- Torén, Kjell, 1952, et al.
(author)
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Chronic airflow limitation and its relation to respiratory symptoms among ever-smokers and never-smokers: a cross-sectional study
- 2020
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In: Bmj Open Respiratory Research. - : BMJ. - 2052-4439. ; 7:1
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Journal article (peer-reviewed)abstract
- Background The diagnosis of chronic obstructive pulmonary disease is based on the presence of persistent respiratory symptoms and chronic airflow limitation (CAL). CAL is based on the ratio of forced expiratory volume in 1 s to forced vital capacity (FEV1:FVC) after bronchodilation, and FEV1:FVC less than the fifth percentile is often used as a cut-off for CAL. The aim was to investigate if increasing percentiles of FEV1:FVC were associated withany respiratory symptom(cough with phlegm, dyspnoea or wheezing) in a general population sample of never-smokers and ever-smokers. Methods In a cross-sectional study comprising 15 128 adults (50-64 years), 7120 never-smokers and 8008 ever-smokers completed a respiratory questionnaire and performed FEV(1)and FVC after bronchodilation. We calculated theirz-scores for FEV1:FVC and defined the fifth percentile using the Global Lung Function Initiative (GLI) reference value, GLI(5)and increasing percentiles up to GLI(25). We analysed the associations between different strata of percentiles and prevalence ofany respiratory symptomusing multivariable logistic regression for estimation of OR. Results Among all subjects, regardless of smoking habits, the odds ofany respiratory symptomwere elevated up to the GLI(15-20)strata. Among never-smokers, the odds ofany respiratory symptomwere elevated at GLI(<5)(OR 3.57, 95% CI 2.43 to 5.23) and at GLI(5-10)(OR 2.57, 95% CI 1.69 to 3.91), but not at higher percentiles. Among ever-smokers, the odds ofany respiratory symptomwere elevated from GLI(<5)(OR 4.64, 95% CI 3.79 to 5.68) up to GLI(>= 25)(OR 1.33, 95% CI 1.00 to 1.75). Conclusions The association between percentages of FEV1:FVC and respiratory symptoms differed depending on smoking history. Our results support a higher percentile cut-off for FEV1:FVC for never-smokers and, in particular, for ever-smokers.
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| 9. |
- Torén, Kjell, 1952, et al.
(author)
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The ratio FEV1/FVC and its association to respiratory symptoms-A Swedish general population study
- 2021
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In: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 41:2, s. 181-191
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Journal article (peer-reviewed)abstract
- Chronic airflow limitation (CAL) can be defined as fixed ratio of forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) any respiratory symptom. In a cross-sectional general population study, 15,128 adults (50-64 years of age), 7,120 never-smokers and 8,008 ever-smokers completed a respiratory questionnaire and performed FEV1 and FVC after bronchodilation. We calculated different ratios of FEV1/FVC from 0.40 to 1.0 using 0.70 as reference category. We analysed odds ratios (OR) between different ratios and any respiratory symptom using adjusted multivariable logistic regression. Among all subjects, regardless of smoking habits, the lowest odds for any respiratory symptom was at FEV1/FVC = 0.82, OR 0.48 (95% CI 0.41-0.56). Among never-smokers, the lowest odds for any respiratory symptom was at FEV1/FVC = 0.81, OR 0.53 (95% CI 0.41-0.70). Among ever-smokers, the odds for any respiratory symptom was lowest at FEV1/FVC = 0.81, OR 0.43 (95% CI 0.16-1.19), although the rate of inclining in odds was small in the upper part, that is FEV1/FVC = 0.85 showed similar odds, OR 0.45 (95% CI 0.38-0.55). We concluded that the odds for any respiratory symptoms continuously decreased with higher FEV1/FVC ratios and reached a minimum around 0.80-0.85, with similar results among never-smokers. These results indicate that the optimal threshold associated with respiratory symptoms may be higher than 0.70 and this should be further investigated in prospective longitudinal studies.
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| 10. |
- Tornhammar, P., et al.
(author)
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Association of cardiometabolic risk factors with hospitalisation or death due to COVID-19: Population-based cohort study in Sweden (SCAPIS)
- 2021
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In: BMJ Open. - : BMJ. - 2044-6055. ; 11:9
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Journal article (peer-reviewed)abstract
- Objective To assess the association of cardiometabolic risk factors with hospitalisation or death due to COVID-19 in the general population. Design, setting and participants Swedish population-based cohort including 29 955 participants. Exposures Cardiometabolic risk factors assessed between 2014 and 2018. Main outcome measures Hospitalisation or death due to COVID-19, as registered in nationwide registers from 31 January 2020 through 12 September 2020. Associations of cardiometabolic risk factors with the outcome were assessed using logistic regression adjusted for age, sex, birthplace and education. Results Mean (SD) age was 61.2 (4.5) and 51.5% were women. 69 participants experienced hospitalisation or death due to COVID-19. Examples of statistically significant associations between baseline factors and subsequent hospitalisation or death due to COVID-19 included overweight (adjusted OR (aOR) vs normal weight 2.73 (95% CI 1.25 to 5.94)), obesity (aOR vs normal weight 4.09 (95% CI 1.82 to 9.18)), pre-diabetes (aOR vs normoglycaemia 2.56 (95% CI 1.44 to 4.55)), diabetes (aOR vs normoglycaemia 3.96 (95% CI 2.13 to 7.36)), sedentary time (aOR per hour/day increase 1.10 (95% CI 1.02 to 1.17)), grade 2 hypertension (aOR vs normotension 2.44 (95% CI 1.10 to 5.44)) and high density lipoprotein cholesterol (aOR per mmol/L increase 0.33 (95% CI 0.17 to 0.65)). Statistically significant associations were not observed for grade 1 hypertension (aOR vs normotension 1.03 (95% CI 0.55 to 1.96)), current smoking (aOR 0.56 (95% CI 0.24 to 1.30)), total cholesterol (aOR per mmol/L increase 0.90 (95% CI 0.71 to 1.13)), low density lipoprotein cholesterol (aOR per mmol/L increase 0.90 (95% CI 0.69 to 1.15)) and coronary artery calcium score (aOR per 10 units increase 1.00 (95% CI 0.99 to 1.01)). Conclusions In a large population-based sample from the general population, several cardiometabolic risk factors were associated with hospitalisation or death due to COVID-19. © Authors 2021
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| 11. |
- Wang, Juan, 1984-
(author)
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Asthma and Rhinitis among Adults in Sweden and China : Risk Factors in the Home Environment
- 2018
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Doctoral thesis (other academic/artistic)abstract
- The main aim of this thesis was to evaluate associations between selected home environment factors and asthma, rhinitis and respiratory symptoms among adults from Sweden, China and northern Europe. Two studies were performed in Sweden, one in China, and one longitudinal cohort study was performed in northern Europe. Dampness/mould was common, and was a main risk factor in all studies. Other risk factors for asthma symptoms in Sweden included window pane condensation in winter, multi-family buildings constructed from 1961-1975, rented apartments, environment tobacco smoke (ETS), and living in a colder climate zone. Higher ventilation flow in Sweden was associated with less asthma symptoms. Risk factors for rhinitis in Sweden included window pane condensation, a higher moisture load, concrete slab foundation constructed before 1991, multi-family buildings constructed from 1976-1985, rented apartments and living in densely populated areas. Risk factors for rhinitis in China included window pane condensation, recent redecoration, new furniture, presence of cockroaches, pet keeping, ETS and living near a main road or highway. Frequently cleaning of the home and putting beddings to sunshine were protective factors for rhinitis in China. Other risk factors for respiratory infections in Sweden included houses with a brick façade, window pane condensation, a higher moisture load, multi-family buildings constructed from 1976-1985, rented apartments and living in densely populated areas. Furthermore, dampness and mould, and mould odour were risk factors for onset of asthma and rhinitis in northern Europe. In conclusion, indoor dampness and mould can be a risk factor for asthma and rhinitis in Sweden, China and northern Europe. Certain construction years (1961-1985), ETS, recent redecoration, new furniture, living in urban areas and exposure to traffic air pollution can be risk factors for asthma, rhinitis or respiratory infections. A high ventilation flow and daily cleaning at home can be protective.
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| 12. |
- Zevenhoven-Onderwater, Maria, et al.
(author)
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The ash chemistry in fluidised bed gasification of biomass fuels. Part I : Predicting the chemistry of melting ashes and ash-bed material interaction
- 2001
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In: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 80:10, s. 1489-1502
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Journal article (peer-reviewed)abstract
- This paper is part I in a series of two describing the modelling of the ash-chemistry of seven biomass fuels under reducing, pressurised conditions in fluidised bed gasification by means of thermodynamic multi-phase multi-component equilibrium (TPCE) calculations. The fuels considered were Salix, a Scandinavian forest residue, Miscanthus, Reed Canary Grass, Eucalyptus, Arundo Donax and Lucerne. The composition and amount of phases have been calculated for the gasification of the fuel as such and in presence of an excess amount of calcite, dolomite, magnesium olivine sand and sand by using TPCE calculations in a temperature interval of 600-900°C and a pressure of 10 bar. It was found that interaction of inorganic compounds released from the fuels with bed material is a prerequisite for the formation of bed agglomerates. The presence of an excess of dolomite decreased the amount of alkali components in the bed, thereby increasing the amount of alkali components volatilised. A silica bed, however, binds most alkali released from the fuel, retaining it in the bed as low melting alkali silicates. The chances of experiencing operating problems due to bed agglomeration may increase hereby significantly. Calculations at atmospheric pressure show that the amounts of melt present will be smaller when compared to pressurised conditions, thereby decreasing the chances of bed agglomeration. In a pressurised gasifier using calcite or dolomite as bed material a small amount of an alkali carbonate rich melt can be expected at temperatures above 620°C with each of the seven biomass fuels fired. In silica-rich cases such as when firing Miscanthus, Reed Canary Grass, Arundo Donax or using a Si-rich bed material a melt can be expected at temperatures above 770°C. The amount of melt is rather high, i.e. 12-100% of the original ash formed. In the case of a magnesium olivine sand bed an alkali melt can be expected at 620°C. At temperatures above 800°C, a silicate melt can form as well. The amount of melt was hi gh, i.e. 60-300% of the original ash formed, showing a significant contribution of the bed material.
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| 13. |
- Zhou, Chunguang, et al.
(author)
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Biomass oxygen/steam gasification in a pressurized bubbling fluidized bed : Agglomeration behavior
- 2016
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In: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 172, s. 230-250
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Journal article (peer-reviewed)abstract
- In this study, the anti-agglomeration abilities of Ca- and Mg-containing bed materials, including dolomite and magnesite, in a pressurized bubbling fluidized bed gasifier using pine pellets and birch chips as feedstock, is investigated. The most typical bed material-silica sand-was also included as a reference for comparison. The sustainability of the operation was evaluated via analyzing the temperatures at different levels along the bed height. During the performances, the aim was to keep the temperature at the bottom zone of the reactor at around 870 °C. However, the success highly depends on the bed materials used in the bed and the temperature can vary significantly in case of agglomeration or bad mixing of bed materials and char particles. Both Glanshammar and Sala dolomites performed well with no observed agglomeration tendencies. In case of magnesite, the bed exhibited a high agglomeration tendency. Silica sand displayed the most severe agglomeration among all bed materials, even when birch chips with a low silica content was fed at a relatively low temperature. The solid samples of all the bed materials were inspected by light microscopy and Scanning Electron Microscopy (SEM). The Energy Dispersive Spectroscopy (EDS) detector was used to detect the elemental distribution in the surface. The crystal chemical structure was analyzed using X-ray Diffraction (XRD). Magnesite agglomerates glued together by big molten ash particles. There was no coating layer detected on magnesite particles at bed temperatures - below 870 °C. But when the temperature was above 1000 °C, a significant amount of small molten ash particles was deposited on the magnesite particles, indicating a pronounced tendency for formation of a coating layer in case of long-term operation. An increasing trend of Si on the surface of dolomite particles was observed. Simultaneously, potassium deposition on the surface is not obvious. The analyses, based on the XRD diffraction and the K2O-SiO2-MgO and K2O-SiO2-CaO ternary diagrams, suggest that the observed decreases in the risks for agglomeration using dolomite, cannot be attributed to formation of alkali-containing compounds with higher melting points, but to the reaction between dolomite and silica, consuming a considerable portion of silicon and thus hinder the formation of low-melting potassium silicate, as well as its ability to stabilize the temperatures under pressurized conditions.
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| 14. |
- Zhou, Chunguang, 1986-, et al.
(author)
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Early Detection of Bed Defluidization in Steam-Oxygen Biomass-Pressurized Fluidized Bed Gasifiers
- 2023
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In: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 63:1, s. 672-690
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Journal article (peer-reviewed)abstract
- In the present study, an improved understanding of dynamic temperature and differential pressure phenomena during pressurized biomass gasification in a bubbling fluidized bed is used to develop a method for the early detection of bed defluidization. Experiments with silica sand as a bed material and three different biomass feedstocks, namely, birch chips, grot chips, and pine pellets, were conducted. For comparison, experiments using magnesite and dolomite as the bed materials were also conducted. The main variables potentially influencing bed fluidization, including K content and K/Si ratio in fuel feedstock, bed temperature, steam, and fluidization velocity, were considered in relation to their effect on bed defluidization time. Correlation of differential pressure and temperature at different positions in the bed with fluidized bed changes, such as char accumulation, sticky coating formation on particles, and char consumption, was evaluated and identified. The study demonstrates that under the operating conditions investigated, it is possible to determine the bed defluidization tendency fairly accurately using a combination of bed temperature deviation and the deviation of two series of dynamic differential pressure signals, measured at different bed positions.
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| 15. |
- Zhou, Chunguang, 1986-, et al.
(author)
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Fragmentation of dolomite bed material at elevated temperature in the presence of H2O & CO2 : Implications for fluidized bed gasification
- 2020
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In: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 260
-
Journal article (peer-reviewed)abstract
- With the aims of improving the understanding of the use of dolomite bed materials in a fluidized bed (FB) gasifier, dolomite primary fragmentation behaviors and mechanisms at elevated temperatures were thoroughly investigated by means of quantitative analysis of particles production, size distribution, and particles shape (in terms of HS circularity and convexity). Crystalline Glanshammar and amorphous Sala dolomites of different original particle sizes (300-350 mu m, 350-500 mu m, and 500-1000 mu m) were treated under various conditions, such as temperatures of 650,750, and 950 degrees C and gas conditions of N-2, N-2 & steam, and H2O & CO2. Crystalline Glanshammar dolomite exhibited severe fragmentation, while amorphous Sala dolomite only fragmented slightly. Fragmentation mechanisms were proposed for amorphous and crystalline dolomite. In case of the Glanshammar dolomite, the release of H2O trapped in the crystal lattices and trace level of CO2 at structure defects, contributed to 10% and 55% of the primary fragmentation, respectively. The presence of CO2 can significantly mitigate the fragmentation of crystalline Glanshammar dolomite, which is probably either due to the prevention of CO2-dissociation at the defects or filling of cations by interchanging CO2- with the dolomite, consequently, allowing for a stabilization of dolomite structure. The analysis shows that elutriation in fluidized bed gasifier can be reduced significantly when either using amorphous Sala dolomite as bed material or treatment of the Glanshammar dolomite in the presence of CO2 before its utilization in a fluidized bed.
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| 16. |
- Zhou, Chunguang, 1986-, et al.
(author)
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Fragmentation of dolomite bed material at elevated temperature in the presence of H2O & CO2: Implications for fluidized bed gasification
- 2020
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In: Fuel. - 0016-2361 .- 1873-7153. ; 260, s. 116340-
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Journal article (peer-reviewed)abstract
- Dolomiteshowssuperiortarcrackingandanti-agglomerationabilitiesingasificationprocesses,whileitsfrag-mentation at elevated temperatures is still a major obstacle inhibiting its applications in fluidized bed (FB)applications.ToimprovetheunderstandingofitsperformanceinpressurizedFBgasification,weinvestigatedfragmentationbehaviorsofcrystallineGlanshammarandamorphousSaladolomiteatbothisothermalandnon-isothermal modes under pressurized H2O and CO2conditions. A series of tests under various conditions, i.e.pressure, temperature, heating rate, gas atmosphere, and dolomite types, was conducted. The primary frag-mentation of Glanshammar is significantly reduced at 10 bar. Dolomite exposed to aPH2Oof 10 bar has thelowestfragmentationamongallcases.Bothdolomiteswerealsoloadedintoapressurizedfluidizedbedgasifierasbedmaterial.Glanshammarexhibitsapproximately14%lossofitsinitialmassofbed,amuchhigherlosscompared to the Sala dolomite with only 5.5%. Fragmentation mechanisms at pressurized conditions in thepresence of H2O and CO2and measures to mitigate dolomite fragmentation in pressurized FB gasifiers areproposed. During gasification, both high operating pressure and highPH2Oare beneficial for fragmentationmitigation.Tomitigateaninitialfragmentationofdolomiteduringthereactorheating-upstage,apressurizationto the operating pressure before reaching the initial fragmentation temperature of dolomite (400 °C) is re-commended. Crystalline dolomite, is the preferred choice, if a pretreatment at a high-pressure using H2O isapplied.
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| 17. |
- Zhou, Chunguang, 1986-, et al.
(author)
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Fragmentation of dolomite bed material at pressurized conditions in the presence of H2O and CO2 : Implications for pressurized fluidized bed gasification
- 2021
-
In: Fuel. - : Elsevier Ltd. - 0016-2361 .- 1873-7153. ; 285
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Journal article (peer-reviewed)abstract
- Dolomite shows superior tar cracking and anti-agglomeration abilities in gasification processes, while its fragmentation at elevated temperatures is still a major obstacle inhibiting its applications in fluidized bed (FB) applications. To improve the understanding of its performance in pressurized FB gasification, we investigated fragmentation behaviors of crystalline Glanshammar and amorphous Sala dolomite at both isothermal and non-isothermal modes under pressurized H2O and CO2 conditions. A series of tests under various conditions, i.e. pressure, temperature, heating rate, gas atmosphere, and dolomite types, was conducted. The primary fragmentation of Glanshammar is significantly reduced at 10 bar. Dolomite exposed to a PH2O of 10 bar has the lowest fragmentation among all cases. Both dolomites were also loaded into a pressurized fluidized bed gasifier as bed material. Glanshammar exhibits approximately 14% loss of its initial mass of bed, a much higher loss compared to the Sala dolomite with only 5.5%. Fragmentation mechanisms at pressurized conditions in the presence of H2O and CO2 and measures to mitigate dolomite fragmentation in pressurized FB gasifiers are proposed. During gasification, both high operating pressure and high PH2O are beneficial for fragmentation mitigation. To mitigate an initial fragmentation of dolomite during the reactor heating-up stage, a pressurization to the operating pressure before reaching the initial fragmentation temperature of dolomite (400 °C) is recommended. Crystalline dolomite, is the preferred choice, if a pretreatment at a high-pressure using H2O is applied.
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| 18. |
- Zhou, Chunguang, et al.
(author)
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Selection of dolomite bed material for pressurized biomass gasification in BFB
- 2017
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In: Fuel processing technology. - : Elsevier. - 0378-3820 .- 1873-7188. ; 167, s. 511-523
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Journal article (peer-reviewed)abstract
- Dolomite is considered advantageous as bed material in fluidized bed gasification processes, due to its catalytic tar cracking and anti-sintering properties. However, in case of pressurized fluidized bed gasifiers, the use of dolomite is challenging. High temperature in the presence of steam favors the production of clean syngas due to the intensified cracking of tar in the presence of CaO, whereas it simultaneously increases the tendency of fragmentation of dolomite particles after full calcination. The present study was carried out to examine the influence of the properties of dolomite on the stability of dolomite in a pressurized fluidized bed gasifier, with the aim of determining criteria for dolomite selection. Glanshanunar dolomite exhibited a better stability in the mechanical strength after calcination, compared to Sala dolomite. The corresponding change of micro-structure that occurred during dolomite chemical transformation was presented. The crystal pattern and Si distribution in the crystal lattice are the possible explanations for the superior performance of the Glanshammar dolomite compared to the Sala dolomite.
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| 19. |
- Zhou, Chunguang, 1986-, et al.
(author)
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Selection of dolomite bed material for pressurized biomass gasification in BFB
- 2017
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In: Fuel processing technology. - : ELSEVIER SCIENCE BV. - 0378-3820 .- 1873-7188. ; 159, s. 460-473
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Journal article (peer-reviewed)abstract
- Dolomite is considered advantageous as bed material in fluidized bed gasification processes, due to its catalytic tar cracking and anti-sintering properties. However, in case of pressurized fluidized bed gasifiers, the use of dolomite is challenging. High temperature in the presence of steam favors the production of clean syngas due to the intensified cracking of tar in the presence of CaO, whereas it simultaneously increases the tendency of fragmentation of dolomite particles after full calcination. The present study was carried out to examine the influence of the properties of dolomite on the stability of dolomite in a pressurized fluidized bed gasifier, with the aim of determining criteria for dolomite selection. Glanshammar dolomite exhibited a better stability in the mechanital strength after calcination, compared to Sala dolomite. The corresponding change of micro-structure that occurred during dolomite chemical transformation was presented. The crystal pattern and Si distribution in the crystal lattice are the possible explanations for the superior performance of the Glanshammar dolomite compared to the Sala dolomite.
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