scholarly journals Assessment of the Impact of Modification of Calcium Sorbents and the Possibility of Their Use in Desulfurization for Oxy-Fuel Combustion Process

Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1284
Author(s):  
Michał Wichliński ◽  
Renata Włodarczyk
Keyword(s):  
Flue Gas ◽  
Mercury Porosimetry ◽  
Combustion Process ◽  
Flue Gas Desulfurization ◽  
Sorption Coefficient ◽  
Lithium Compounds ◽  
Process Modification ◽  
The Absolute ◽  
Reactivity Coefficient ◽  
The Impact

The paper describes the possibilities of simple and effective modification of calcium sorbents used for flue gas desulfurization with a size between of 125–250 µm. The additives to the sorbents in the amount of 0.5% and 1.0% were inorganic sodium and lithium compounds. The research on the reactivity of sorbents was analyzed in the process of simultaneous calcination and sulfation at the temperature of 850 °C. The type of Na+ or Li+ cations and the inorganic salt anions have an influence on the modification of calcium sorbents in order to improve the efficiency of the calcination and sulfation process. Modification of calcium sorbents by adding inorganic sodium and lithium compounds, regardless of the amount, changes the reactivity coefficient RI [mol/mol] and the absolute sorption coefficient CI [g S/kg sorbent]. In the case of inorganic sodium salt (Additive 1), regardless of the amount of modifier added, there was a visible improvement in the reactivity of the sorbent: 1.0% of the additive caused an increase in the RI coefficient in relation to the raw sorbent by over 14%, and in the case of the CI coefficient by over 24%. Additional research was the analysis of the limestone behavior mechanism during the simultaneous calcination and sulfation (SCS) process under conditions of elevated temperature and with variable CO2 and O2 contents in the flue gas. The behavior of sorbents with a size distribution of 125–250 µm was assessed on the basis of the change in mass of the samples by determining the reactivity coefficient RI, [mol/mol] and the absolute sorption coefficient CI, [g S/kg sorbent]. Using the mercury porosimetry technique, the change in sorbent porosity in the subsequent stages of the simultaneous calcination and sulfation process was investigated. The process was carried out in the temperature range corresponding to the oxy-combustion (i.e., from 850 °C to 1000 °C).

The Partition Period of Thermodynamic Calculation and the Numerical Simulation for Lignite Blended Supercritical Boiler

2014 ◽  
Vol 1030-1032 ◽  
pp. 648-652
Author(s):  
Cai Ying Ban ◽  
Xu Ao Lu ◽  
Jian Meng Yang ◽  
Xu Ran ◽  
Feng Ying Liang
Keyword(s):  
Numerical Simulation ◽  
Flue Gas ◽  
Thermodynamic Calculation ◽  
Heat Load ◽  
Combustion Process ◽  
Heating Surface ◽  
Gas Temperature ◽  
Boiler Furnace ◽  
Geometry Model ◽  
The Impact

The purpose of this paper is to study the impact of furnace temperature and load after blending in lignite, based on CFD software FLUENT-6.3,this paper choose the appropriate geometry model and the physical and mathematical models, and numerical simulation of the different conditions 600MW supercritical once-through boiler blending lignite furnace combustion process is curried out. And through a 600MW supercritical coal-fired boiler furnace lignite blended performed sections thermodynamic calculation under different conditions, worked out the furnace flue gas temperature, CO, CO2concentration distribute trend and radiant heat each section surface heat load conditions. The specific amount were blended with 5%, 10%, 15%, 20% were not dried lignite and dried lignite 20% after five conditions. And obtained a conclusion is the temperature and radiation heating surface flue gas heat load in the overall trend under the various conditions.

scholarly journals Gas Combustion Efficiency Enhancement: Application Study of Intense Elestrostatic Field

2019 ◽  
Vol 56 (4) ◽  
pp. 3-16
Author(s):  
O. Krickis ◽  
N. Zeltins
Keyword(s):  
Electrostatic Field ◽  
Flue Gas ◽  
Combustion Process ◽  
Field Application ◽  
Process Efficiency ◽  
Simultaneous Increase ◽  
Efficiency Enhancement ◽  
Gas Temperature ◽  
Gas Combustion ◽  
The Impact

Abstract A number of international, European Union and Latvian legislative acts have been developed, which regulate the efficiency of gas combustion plants and greenhouse gas emissions in the atmosphere. These legislative acts require the development of new scientifically efficient methods for gas optimal combustion with a minor impact on the environment. In order to achieve such a goal, different methods can be used, but the most efficient is an intensive electrostatic field application to control combustion and harmful emission formation in premixed flames. In the framework of the current study, the authors developed a hybrid burner, which allowed generating an intensive electrostatic field with intensity of more than 1000 kV/m. The study also investigated the impact of such a field on the formation of harmful emissions, including CO2 and flue gas temperature. The empirical results showed that an intensive DC electrostatic field generated inside of the burner had an impact on the flame shape, CO2, NOx emissions and flue gas temperature. In its turn, by applying an intensive pulsating electrostatic field (multivariable experiment) it was possible to achieve the reduction in NOx, CO emissions with a simultaneous increase in flue gas temperature, which was related to combustion process efficiency enhancement.

Flue Gas Recirculation in a Gas Turbine: Impact on Performance and Operational Behavior

2011 ◽  
Author(s):  
Frank Sander ◽  
Richard Carroni ◽  
Stefan Rofka ◽  
Eribert Benz
Keyword(s):  
Power Plant ◽  
Co2 Capture ◽  
Flue Gas ◽  
Power Plants ◽  
Combustion Process ◽  
Combined Cycle ◽  
Flue Gas Recirculation ◽  
Overall Performance ◽  
Gas Recirculation ◽  
The Impact

The rigorous reduction of greenhouse gas emissions in the upcoming decades is only achievable with contribution from the following strategies: production efficiency, demand reduction of energy and carbon dioxide (CO2) capture from fossil fueled power plants. Since fossil fueled power plants contribute largely to the overall global greenhouse gas emissions (> 25% [1]), it is worthwhile to capture and store the produced CO2 from those power generation processes. For natural-gas-fired power plants, post-combustion CO2 capture is the most mature technology for low emissions power plants. The capture of CO2 is achieved by chemical absorption of CO2 from the exhaust gas of the power plant. Compared to coal fired power plants, an advantage of applying CO2 capture to a natural-gas-fired combined cycle power plant (CCPP) is that the reference cycle (without CO2 capture) achieves a high net efficiency. This far outweighs the drawback of the lower CO2 concentration in the exhaust. Flue Gas Recirculation (FGR) means that flue gas after the HRSG is partially cooled down and then fed back to the GT intake. In this context FGR is beneficial because the concentration of CO2 can be significantly increased, the volumetric flow to the CO2 capture unit will be reduced, and the overall performance of the CCPP with CO2 capture is increased. In this work the impact of FGR on both the Gas Turbine (GT) and the Combined Cycle Power Plant (CCPP) is investigated and analyzed. In addition, the impact of FGR for a CCPP with and without CO2 capture is investigated. The fraction of flue gas that is recirculated back to the GT, need further to be cooled, before it is mixed with ambient air. Sensitivity studies on flue gas recirculation ratio and temperature are conducted. Both parameters affect the GT with respect to change in composition of working fluid, the relative humidity at the compressor inlet, and the impact on overall performance on both GT and CCPP. The conditions at the inlet of the compressor also determine how the GT and water/steam cycle are impacted separately due to FGR. For the combustion system the air/fuel-ratio (AFR) is an important parameter to show the impact of FGR on the combustion process. The AFR indicates how close the combustion process operates to stoichiometric (or technical) limit for complete combustion. The lower the AFR, the closer operates the combustion process to the stoichiometric limit. Furthermore, the impact on existing operational limitations and the operational behavior in general are investigated and discussed in context of an operation concept for a GT with FGR.

Pressurised Oxy-Coal Combustion Rankine-Cycle for Future Zero Emission Power Plants: Process Design and Energy Analysis

2008 ◽  
Author(s):  
Marco Gazzino ◽  
Giancarlo Benelli
Keyword(s):  
Flue Gas ◽  
Process Design ◽  
Energy Analysis ◽  
Combustion Process ◽  
Rankine Cycle ◽  
Air Separation ◽  
Regenerative Heat ◽  
Separation Unit ◽  
High Heat Transfer ◽  
The Impact

This paper presents the process design and the energy analysis for a coal-fired power plant based on pressurised oxycoal combustion and including carbon capture technologies. A combustion technology performing a pressurised combustion of coal in an atmosphere of O2/CO2/H2O and including flue gases recycling has been selected. Combustion and steam production occur in separated equipments and the combustor’s design allows achieving high ash removal efficiency. The Rankine cycle has been chosen as the most viable thermodynamic cycle in a short-term scenario. Oxygen required by the combustion process is supplied by a cryogenic Air Separation Unit (ASU) and a double-reheat ultrasupercritical cycle is employed with main steam conditions of 250bar/605°C and reheat steam temperatures of 605°C/620°C. All choices related to thermal cycle selection and process design have been conducted upon the principle of feasibility and reliability. In order to increase net plant efficiency both sensible and latent heat is recovered from the flue gas stream before entering the purification and compression section. By operating in pressure it becomes possible to recover a larger amount of heat than in the atmospheric case. As a result, all low pressure steam bleedings and the corresponding regenerative heat exchangers can be eliminated. Process simulation is carried out in the paper and the expected efficiency is evaluated, as well as other cycle performance parameters. Since a relevant benefit may arise from the combustion of cheap coals, the impact of burning high-ash content and low ash-fusion-temperature coals is assessed. The impact of energy penalties associated to oxygen production and the benefit arising from high heat-transfer coefficients due to the increased pressure of the flue gas are deeply investigated.

scholarly journals Experimental and numerical study on combustion of baled biomass in cigar burners and effects of flue gas re-circulation

2016 ◽  
Vol 20 (suppl. 1) ◽  
pp. 151-165 ◽  
Author(s):  
Aleksandar Eric ◽  
Stevan Nemoda ◽  
Dragoljub Dakic ◽  
Branislav Repic ◽  
Dejan Djurovic
Keyword(s):  
Combustion Chamber ◽  
Flue Gas ◽  
Numerical Study ◽  
Combustion Process ◽  
Maximum Temperature ◽  
Biomass Combustion ◽  
Biomass Ash ◽  
Maximum Temperatures ◽  
Gas Recirculation ◽  
The Impact

The paper presents results of experimental and numerical investigation addressing combustion of baled agricultural biomass in a 50 kW experimental furnace equipped with cigar burners. Experiments performed included measurements of all parameters deemed important for mass and energy balance, as well as parameters defining quality of the combustion process. Experimental results were compared with results of numerical simulations performed with previously developed CFD model. The model takes into account complex thermo mechanical combustion processes occurring in a porous layer of biomass bales and the surrounding fluid. The combustion process and the corresponding model were deemed stationary. Comparison of experimental and numerical results obtained through research presented in this paper showed satisfactory correspondence, leading to the conclusion that the model developed could be used for analysis of different effects associated with variations in process parameters and/or structural modifications in industrial biomass facilities. Mathematical model developed was also utilized to examine the impact of flue gas recirculation on maximum temperatures in the combustion chamber. Gas recirculation was found to have positive effect on the reduction of maximum temperature in the combustion chamber, as well as on the reduction of maximum temperature zone in the chamber. The conclusions made provided valuable inputs towards prevention of biomass ash sintering, which occurs at higher temperatures and negatively affects biomass combustion process.

Prognostic value of absolute monocyte count in chronic lymphocytic leukaemia

2015 ◽  
Vol 156 (15) ◽  
pp. 592-597
Author(s):  
László Szerafin ◽  
János Jakó ◽  
Ferenc Riskó
Keyword(s):  
Chronic Lymphocytic Leukaemia ◽  
Prognostic Value ◽  
Lymphocytic Leukaemia ◽  
Treatment Time ◽  
Monocyte Count ◽  
Time To Treatment ◽  
Causes Of Mortality ◽  
The Absolute ◽  
The Impact ◽  
Overal Survival

Introduction: The low peripheral absolute lymphocyte and high monocyte count have been reported to correlate with poor clinical outcome in various lymphomas and other cancers. However, a few data known about the prognostic value of absolute monocyte count in chronic lymphocytic leukaemia. Aim: The aim of the authors was to investigate the impact of absolute monocyte count measured at the time of diagnosis in patients with chronic lymphocytic leukaemia on the time to treatment and overal survival. Method: Between January 1, 2005 and December 31, 2012, 223 patients with newly-diagnosed chronic lymphocytic leukaemia were included. The rate of patients needing treatment, time to treatment, overal survival and causes of mortality based on Rai stages, CD38, ZAP-70 positivity and absolute monocyte count were analyzed. Results: Therapy was necessary in 21.1%, 57.4%, 88.9%, 88.9% and 100% of patients in Rai stage 0, I, II, III an IV, respectively; in 61.9% and 60.8% of patients exhibiting CD38 and ZAP-70 positivity, respectively; and in 76.9%, 21.2% and 66.2% of patients if the absolute monocyte count was <0.25 G/l, between 0.25–0.75 G/l and >0.75 G/l, respectively. The median time to treatment and the median overal survival were 19.5, 65, and 35.5 months; and 41.5, 65, and 49.5 months according to the three groups of monocyte counts. The relative risk of beginning the therapy was 1.62 (p<0.01) in patients with absolute monocyte count <0.25 G/l or >0.75 G/l, as compared to those with 0.25–0.75 G/l, and the risk of overal survival was 2.41 (p<0.01) in patients with absolute monocyte count lower than 0.25 G/l as compared to those with higher than 0.25 G/l. The relative risks remained significant in Rai 0 patients, too. The leading causes of mortality were infections (41.7%) and the chronic lymphocytic leukaemia (58.3%) in patients with low monocyte count, while tumours (25.9–35.3%) and other events (48.1 and11.8%) occurred in patients with medium or high monocyte counts. Conclusions: Patients with low and high monocyte counts had a shorter time to treatment compared to patients who belonged to the intermediate monocyte count group. The low absolute monocyte count was associated with increased mortality caused by infectious complications and chronic lymphocytic leukaemia. The absolute monocyte count may give additional prognostic information in Rai stage 0, too. Orv. Hetil., 2015, 156(15), 592–597.

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