Biomass Combustion Process Research Articles

Development of a numerical method for the rapid prediction of ignition performance of biomass particles

Ignition is a critical step of the combustion process of biomass, due to its substantial impact on flame characteristics, process efficiency, and pollutant formation. This paper aims to develop a robust zero-dimensional ignition model as an effective tool to quickly estimate the ignition behaviour of biomass fuels. The numerical approach integrates an established devolatilization model with a well-tested mechanism for gas-phase reaction kinetics. The ignition delay time is determined from the sum of the devolatilization time and ignition time of the evolved gas species, as specified by the maximum in the OH radical concentration. The central premise of the modelling routine is that kinetics govern the ignition delay during biomass initial heating and thermochemical conversion which makes the elemental fuel composition the most important fuel property and heating rate the most important reactor condition. The predictions of the model are tested and verified against published experimentally measured ignition data for seven pulverized biomass fuels and are found to be in good agreement. The model for the first time can reasonably distinguish ignition behaviours of different biomass fuels, enabling its use in wider industrial applications.

Life Cycle Assessment Applied to End-of-Life Scenarios of Sargassum spp. for Application in Civil Construction

Environmental risks and vulnerabilities in coastal regions include the massive deposits of brown algae of the genus Sargassum in regions such as the Caribbean, Gulf of Mexico, and northern Brazil. Efforts have been made to turn this problem into an opportunity by seeking new uses for this biomass in the sectors of food, agriculture, health, biofuels, bioremediation, and civil construction. Thus, this study aimed to produce quantitative data for different end-of-life scenarios of the Sargassum algae, seeking for potential applications of this macroalgae in the civil construction sector. For this purpose, we conducted a life cycle assessment (LCA) study of the Sargassum algae, in its natural destination, and evaluated its potential impact. This evaluation was then compared to the possible impacts of alternatives to their end of life, such as landfill disposal, drying and grinding to use as fibers or particles, burning the biomass to generate energy and fly ash, using a consequential LCA and the indicators of the ReCiPe 2016 method. For each of the proposed scenarios, the functional unit of 1 kg of the three types of unprocessed Sargassum algae that are found in the Brazilian deposits (natans I, natans VIII, and fluitans) was considered separately, and also for a composition that is closer to that found in the Brazilian deposits (50% fluitans, 15% natans I, and 35% natans VIII). The results for both natural decomposition scenarios demonstrated a dominant contribution to the categories of impact for climate change, marine eutrophication, and land use, thus justifying the search for new initiatives for the use of the algae. The burning process showed a significant contribution to most of the indicators, with emphasis on the massive generation of particulate, inherent to the biomass burning process; however, it showed a reduction in the magnitude of climate change emissions from around 47% to less than 2%. Finally, the proposed scenario of processing Sargassum biomass to obtain particles presented prevalence of magnitude for potential impact in most of the proposed indicators, due to the processes with high electricity consumption, but keeping climate change emissions’ relative reduction from 47% to 6%. Thus, new studies may further investigate the potential of application of these materials in different products and components of civil construction.

The Effect of CaO on the CO and NOx Emission Characteristics of Fast-Growing Grass Combustion

Fast-growing grass is a biomass material with characteristics such as high temperature and drought resistance; rapid growth and development; and repeated germination and cutting. Therefore, it is a popular biomass fuel. It is required that the pollutants produced during the biomass combustion process are appropriately controlled. For this purpose, our study analyses the influence of combustion temperature and calcium oxide (CaO) on the nitrogen oxides (NOx) and carbon monoxide (CO) emission characteristics of fast-growing grass combustion using the biomass combustion flue gas analysis and testing platform. The results of our analysis revealed that CaO additive can simultaneously reduce the peak and total NOx emissions at 750 °C. Particularly, 5% CaO demonstrated a significant control effect on the NOx emission from the fast-growing grass combustion process, with a peak and total emissions reduction of 47.05% and 56.81%, respectively. In addition, with an increase in temperature, the CO emission curve attains a second peak higher than the first peak, and the peak and total emissions show a decreasing trend.

A comprehensive pyrolysis model for lignocellulosic biomass particles with a special emphasis on the anisotropic characteristics

The porous and fibrous structural tissue of lignocellulosic biomass serves as a transport channel for water and nutrients along the growth direction, indicating a highly anisotropic nature of biomass. The anisotropies of the thermal and structural properties of biomass have substantial influences on particle-scale reactions, transport processes, and morphological evolution during thermal conversions. An in-depth investigation of the anisotropic characteristics of these physicochemical phenomena in pyrolysis benefits in the understanding of biomass gasification and combustion processes. In this study, a comprehensive 2D axisymmetric mathematical model is developed to quantitatively analyze the pyrolysis behaviors of a cylindrical wood particle with or without anisotropy. Correlative unsteady energy and mass conservation equations are combined with a multistep kinetic model of biomass devolatilization. To improve the numerical descriptions of volatiles flowing in a porous biomass matrix, the constitutive equations of the Brinkman equation and dusty gas model are adopted. Moreover, a binary differential equation is used to calculate the simultaneous changes in the pore structure and shrinkage of the wood particles. When considering anisotropy, validations of the model against literature data demonstrate that it can reliably predict the intraparticle temperature profiles, weight loss, and particle shrinking degree of lignocellulosic biomass. Using this model, the coupling effects of multi-physical fields and reactions inside pyrolyzing wood particles are explored. It is revealed that the anisotropic characteristics of biomass influence not only the orientations of intraparticle heat and mass transport processes but also their mechanisms, resulting in varying degrees of secondary reactions and particle shrinkage.

Bibliometric Analysis of the Alternative Biomass Types and Biomass Combustion Technologies

Abstract As renewable energy demand grows, different sectors (especially energy and household) face increasing fuel shortages. Increasing interest in alternative biomass for heat production also increases the need to develop appropriate combustion technologies. This paper investigates studies carried out in the context of renewable energy. The main objectives of the article are to identify the trends between alternative biomass types and combustion processes and to find binding keywords between the topics mentioned. Two bibliometric methods – performance analysis and science mapping analysis – are applied to analyse scientific literature related to the specific application from the Scopus database. Performance analysis results show that the number of publications and citations on using alternative biomass in energy is increasing annually. The most significant number of publications in terms of biomass types are municipal solid waste and algae, while in terms of combustion technologies, it is about direct combustion and gasification. According to the results of scientific mapping analysis, algae has a strong link to climate change and sustainability issues.

Quantitative Tomographic Laser Absorption Imaging of Atomic Potassium during Combustion of Potassium Chloride Salt and Biomass.

Gaseous potassium (K) species play an important role in biomass combustion processes, and imaging techniques are powerful tools to investigate the related gas-phase chemistry. Here, laser absorption imaging of gaseous atomic K in flames is implemented using tunable diode laser absorption spectroscopy at 769.9 nm and a high-speed complementary metal oxide semiconductor (CMOS) camera recording at 30 kfps. Atomic K absorption spectra are acquired for each camera pixel in a field of view of 28 × 28 mm at a rate of 100 Hz. The technique is used to determine the spatial distribution of atomic K concentration during the conversion of potassium chloride (KCl) salt and wheat straw particles in a laminar premixed CH4/air flame with an image pixel resolution of up to 120 μm. Due to axisymmetry in setup geometry and, consequently, atomic K distributions, the radial atomic K concentration fields could be reconstructed by one-dimensional tomography. For the KCl sample, the K concentration field was in excellent agreement with previous point measurements. In the case of wheat straw, atomic K concentrations of around 3 ppm were observed in a cylindrical flame during devolatilization. In the char conversion phase, a spherical layer of atomic K, with concentrations reaching 25 ppm, was found within 5 mm of the particle surface, while the concentration rapidly decreased to sub-ppm levels along the vertical axis. In both cases, a thin (∼1 mm) layer without any atomic K was observed in close vicinity to the particle, suggesting that the potassium was initially not released in its atomic form.

Increasing the reliability of biomass solid fuel combustion using a combined regenerative heat exchanger as an indirect burner

In this study, an indirect burner system for solid biomass fuel is designed. The design is motivated by the need to solve the problem related to a direct burner system, such as slagging and high pollutant emissions due to the high-temperature burning process. Therefore, the utilization of an indirect burner is expected to improve the reliability of the solid biomass combustion process. It also can be used to reduce coal consumption by using an indirect burner where the working fluid reaches a relatively higher temperature before entering the boiler. The design used the first principle method for creating the regenerator heat exchanger. The regenerator consists of a mantle and coil heat exchanger. The test used solid biomass fuel for the combustion process where the working fluid first enters the mantle heat exchanger and then the coil heat exchanger. As a result, the mantle absorbs sufficient heat losses from the combustion chamber with the highest temperature increment of 19 °C. The warm water from the mantle then flows to the coil arrangement within the combustion chamber. As a result, the highest temperature of the coil is 84.5 °C. The heat transfer rate for the coil and mantle is 57.2–85.6 and 124.9–141.5 W. The key finding is that the combined regenerative heat exchanger can deliver a higher transfer rate. This can be achieved since the heat exchanger utilizes the same flow distribution, increasing the mean temperature differences at the inlet. Thus, it can produce an average heat transfer rate of 210.5 W. Therefore, energy consumption for coal or other fossil fuels can be reduced significantly. The data can be used for further improvement of the existing boiler system and help to increase the thermal efficiency of the system.

Slow thermal decomposition of lignocelluloses compared to numerical model: Fine particle emission, gaseous products analysis

This paper is focused on aerosol fine particle release during the thermal decomposition of beech wood samples with identical mass under an oxidizing and inert atmosphere. This thermal degradation of wood is a significant part of the biomass combustion and pyrolytic process. This contribution focuses on nanoparticles emission with specifying sizes and concentrations in the range of 18–545 nm during thermal degradation processes and determining correlations between individual thermal degradation processes of a wood sample with the same weights but with different heating rates. The flue gases' chemical composition was simultaneously analyzed using a quadrupole mass spectrometer during the thermal degradation process. The weight loss of the sample and its derivation were monitored using a thermogravimeter. This combination made it possible to identify the ranges with the highest particle emission concerning the wood sample and the sample's heating rate. The fine particle identification apparatus uses a Scanning Mobility Particle Sizer and a condensation particle counter. This experimentally obtained data were then compared with the numerical model CPD-Bio. In this case, the comparison was focused on the prediction of the temperatures of the individual pyrolysis stages, at which gaseous products and especially tars are formed.

The role of sources and meteorology in driving PM2.5-bound chlorine

The role of chloride in atmospheric chemistry received increased attention over recent years. Given the primary and chemical-active nature of PM2.5-bound chlorine (p-Cl-), it makes sense to get to know the sources and processes of p-Cl-. The temporal behavior of observed p-Cl- concentration based on 1-h high resolution exhibited seasonal variation of high in winter, low in summer and diurnal variation of high in the morning, low in afternoon. Meteorological normalization technique based on random forest was used to disentangle the effects of emission changes which affected the seasonal variation and meteorology which was related to diurnal variation on p-Cl-. Generalized additive model (GAM) identified RH and temperature as the key meteorological factors of p-Cl- generation, and p-Cl- pollution was serious under the condition of low temperature and high RH. Dispersion-normalized positive matrix factorization (DN-PMF) was used to apportion the p-Cl- to its sources, finding that coal combustion was the main source of p-Cl-, followed by biomass burning and industrial process emissions. Our results will provide the basis for further analysis the causes of p-Cl- pollution and composite air pollution control strategies.

Evaluation of the efficiency of a Venturi scrubber in particulate matter collection smaller than 2.5µm emitted by biomass burning.

Energy demand has increased worldwide, and biomass burning is one of the solutions most used by industries, especially in countries that have a great potential in agriculture, such as Brazil. However, these energy sources generate pollutants, consisting of particulate matter (PM) with a complex chemical composition, such as sugarcane bagasse (SB) burning. Controlling these emissions is necessary; therefore, the aim was to evaluate PM collection using a rectangular Venturi scrubber (RVS), and its effects on the composition of the PM emitted. Considering the appropriate use of biomass as an industrial fuel and the emerging need for a technique capable of efficiently removing pollutants from biomass burning, this study shows the control of emissions as an innovation in a situation such as the industrial one with the use of a Venturi scrubber in fine particle collection, in addition to using portable and representative isokinetic sampling equipment of these particles. The pilot-scale simulation of the biomass burning process, the representative sampling of fine particles and obtaining parameters to control pollutant emissions for a Venturi scrubber, meets the current situation of concern about air quality. The average collection efficiency values were 96.6% for PM> 2.5, 85.5% for PM1.0–2.5, and 66.9% for PM< 1.0. The ionic analysis for PM< 1.0 filters showed potassium, chloride, nitrate, and nitrite at concentrations ranging from 20.12 to 36.5 μg/m3. As the ethanol and sugar plants will continue to generate electricity with sugarcane bagasse burning, emission control technologies and cost-effective and efficient portable samplers are needed to monitor particulate materials and improve current gas cleaning equipment projects.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-022-22786-3.

Measurement report: Large contribution of biomass burning and aqueous-phase processes to the wintertime secondary organic aerosol formation in Xi'an, Northwest China

Abstract. Secondary organic aerosol (SOA) plays an important role in particulate air pollution, but its formation mechanism is still not fully understood. The chemical composition of non-refractory particulate matter with a diameter ≤2.5 µm (NR-PM2.5), OA sources, and SOA formation mechanisms were investigated in urban Xi'an during winter 2018. The fractional contribution of SOA to total OA mass (58 %) was larger than primary OA (POA, 42 %). Biomass-burning-influenced oxygenated OA (OOA-BB) was resolved in urban Xi'an and was formed from the photochemical oxidation and aging of biomass burning OA (BBOA). The formation of OOA-BB was more favorable on days with a larger OA fraction and higher BBOA concentration. In comparison, the aqueous-phase processed oxygenated OA (aq-OOA) was more dependent on the secondary inorganic aerosol (SIA) content and aerosol liquid water content (ALWC), and it showed a large increase (to 50 % of OA) during SIA-enhanced periods. Further van Krevelen (VK) diagram analysis suggests that the addition of carboxylic acid groups with fragmentation dominated OA aging on reference days, while the increased aq-OOA contributions during SIA-enhanced periods likely reflect OA evolution due to the addition of alcohol or peroxide groups.

Effect of water vapor content on corrosion performance of aluminide coatings on TP347H in a simulated biomass combustion environment

Large numbers of power plants are taking biomass energy to replace fossil fuels. However, biomass combustion process deposits a substantial amount of potassium chloride in the boiler pipe, which causes high-temperature corrosion. This paper investigated the corrosion mechanism of aluminide coatings deposited on TP347H stainless steel under experimental conditions with different water vapor content in a simulated biomass combustion environment. H2O promoted the production of more dense multilayer metal oxides in the aluminide coating on the TP347H stainless steel in the presence of water vapor. The coatings suffered the most severe intergranular attack without water vapor. The intergranular corrosion of coatings subjected to 30% water vapor was less severe than that of coatings exposed to 15% water vapor due to the corrosion inhibiting impact of water vapor. It is indicated that water vapor can essentially influence the corrosion process in a biomass combustion environment.

Arctic spring and summertime aerosol optical depth baseline from long-term observations and model reanalyses – Part 2: Statistics of extreme AOD events, and implications for the impact of regional biomass burning processes

Abstract. In a companion paper (Xian et al., 2022, part 1 of the study), we present an Arctic aerosol optical depth (AOD) climatology and trend analysis for 2003–2019 spring and summertime periods derived from a combination of aerosol reanalyses, remote-sensing retrievals, and ground observations. Continued from the previous discussion and as the second part of the study, we report the statistics and trends of Arctic AOD extreme events using the U.S. Navy Aerosol Analysis and Prediction System ReAnalysis version 1 (NAAPS-RA v1), the sun photometer data from the AErosol RObotic NETwork (AERONET) sites, and the oceanic Maritime Aerosol Network (MAN) measurements. Here, extreme AOD events are defined as events with AOD exceeding the 95th percentile (denoted “AOD95”) of AOD distributions for given locations using 6-hourly or daily AOD data. While AERONET and MAN data estimate the Arctic median 550 nm AOD value to be 0.07, the 95th percentile value is 0.24. Such extreme events are dominated by fine-mode aerosol particles, largely attributable to biomass burning (BB) smoke events for the North American Arctic, the Asian Arctic, and most areas of the Arctic Ocean. However, extreme AOD events for the lower European Arctic are more attributable to anthropogenic and biogenic fine particles. The extreme-event occurrence dominance of sea salt is largely limited to the North Atlantic and Norwegian Sea. The extreme AOD amplitudes of anthropogenic and biogenic fine-mode and sea salt AOD are, however, significantly lower than those regions where extreme smoke AOD is dominant. Even for sites distant from BB source regions, BB smoke is the principal driver of AOD variation above the AOD95 threshold. Maximum AOD values in the high Arctic in 2010–2019 have increased compared to 2003–2009, indicating stronger extreme BB smoke influence in more recent years. The occurrence of extreme smoke events tended to be more equally distributed over all months (April–August) during the 2003–2009 period while being more concentrated in the late season (July–August) during the 2010–2019 period. The temporal shift of the occurrence of AOD extreme events is likely due to improved control of early-season agriculture burning, climate-change-related increases in summertime lightning frequencies, and a reduction in anthropogenic pollution over the 2010–2019 period.

CAPTURING OF CARBON DI OXIDE AND PREVENTION OF CORROSION IN BIOMASS PRODUCTION

The generation of heat, electricity is being produced through biomass burning process, but it is seen that it has many challenges. The capture and storage of CO2emissions produced from the combustion of biomass and many other industrialization processes is a great deal to the world. Carbon di oxide emission percentage is continuously increasing in the atmosphere, thus this leads to the climate change in the form of global warming. This study analyses the viable and potent method of capturing carbon di oxide, transporting it in an affordable way and finally then safe storage of itself and increase the temperature as well as corrosive resistivity. KEYWORDS: - Pre combustion capture, post combustion capture, biogas, biogas digester,ccs

Source identification and toxicity apportionment of polycyclic aromatic hydrocarbons in surface soils in Beijing and Tianjin using a PMF-TEQ method.

Beijing and Tianjin are two of the largest cities in northern China with high population densities and highly developed manufacturing industries. In the past decade, some authors have reported their PAH concentrations in surface soils, identified their sources and quantitatively reported their health risks. However, the contributions of different PAH sources to their toxicity have not been reported thus far. In this study, we reviewed the PAH concentrations, contributions of different sources to the toxicity, and cancer risks in soils from different land use types found within Beijing and Tianjin from data gathered by 41 studies. The total PAH concentration varied in the range of 175.7–1989.0 ng g-1 with a higher median PAH concentration detected in urban soils (789.7 ng g-1), followed by suburban soils (647.3 ng g-1) and rural soils (390.8 ng g-1). Source identification using diagnostic ratios and principal component analysis (PCA) suggested that the PAHs in all three land use types mainly originated from biomass and coal combustion, vehicular emissions, and petrogenic processes with contributions varying from 13% to 62%. Furthermore, results from a positive matrix factorization (PMF) model suggested that vehicular emissions and coal combustion in urban soils, and the vehicular emissions, coal combustion and biomass combustion in suburban and rural soils dominated the total PAH concentrations (>85%). These results were consistent with those of the PCA model. Results of the additional toxicity apportionment performed using the PMF model suggested that vehicular emissions and coal combustion contributed the most to the toxic equivalent quantity for Benzo(a)Pyrene (BaPTEQ) and, by extension, to the carcinogenic potencies. The incremental lifetime cancer risk (ILCR) values suggested a low risk level for adults exposed to PAHs in the different land use types found within Beijing and Tianjin.

Gaseous emissions from advanced CLC and oxyfuel fluidized bed combustion of coal and biomass in a complex geometry facility:A comprehensive model

Since the formation of gaseous pollutants during solid fuel combustion in circulating fluidized bed (CFB) units, especially under oxyfuel combustion and chemical looping combustion conditions, is an extremely complex process, the development of a simple predictive model of gas emissions is of practical significance. This paper introduces a novel approach based on fuzzy logic (FL), one of the main artificial intelligence (AI) methods, for the prediction of CO2, CO, NOx (i.e., NO + NO2), N2O, and SOx (i.e., SO2 + SO3) concentrations in flue gases from coal and biomass combustion in various operational sceneries. The simulations are carried out for different combustion environments, i.e., air-firing, oxyfuel, iG-CLC (in-situ gasification chemical looping combustion), and CLOU (chemical looping with oxygen uncoupling), under a wide range of operating parameters. A mixture of oxygen with CO2 was used for oxyfuel combustion. Three different oxygen carriers (OC) were examined in the study for iG-CLC and CLOU, i.e., ilmenite, copper oxide (60% wt.) with the support of carbonate waste from ore flotation, and copper oxide (60% wt.) with the support of ilmenite (20% wt.) and fly ash. The validation of the model was successfully performed on a complex geometry laboratory–scale 5 kWth Dual-Fluidized-Bed Chemical-Looping-Combustion of Solid-Fuels (DFB-CLC-SF) facility. The gaseous pollutant emissions predicted using the developed model were in good agreement with experimental results. The maximum relative error between measured and predicted by the model emissions was lower than 8%. The proposed method constitutes a quick and easy-to-run technique and a complementary tool compared to the experimental procedures and the programmed computing approach. The developed fuzzy logic-based model of gaseous emissions from advanced combustion (GasAdComb) of solid fuels can be easily applied by scientists and engineers to simulate and optimize coal and biomass combustion processes.

Global Emissions of Hydrogen Chloride and Particulate Chloride from Continental Sources.

Gaseous and particulate chlorine species play an important role in modulating tropospheric oxidation capacity, aerosol water uptake, visibility degradation, and human health. The lack of recent global continental chlorine emissions has hindered modeling studies of the role of chlorine in the atmosphere. Here, we develop a comprehensive global emission inventory of gaseous HCl and particulate Cl- (pCl), including 35 sources categorized in six source sectors based on published up-to-date activity data and emission factors. These emissions are gridded at a spatial resolution of 0.1° × 0.1° for the years 1960 to 2014. The estimated emissions of HCl and pCl in 2014 are 2354 (1661-3201) and 2321 (930-3264) Gg Cl a-1, respectively. Emissions of HCl are mostly from open waste burning (38%), open biomass burning (19%), energy (19%), and residential (13%) sectors, and the major sources classified by fuel type are combustion of waste (43%), biomass (32%), and coal (25%). Emissions of pCl are mostly from biofuel (29%) and open biomass burning processes (44%). The sectoral and spatial distributions of HCl and pCl emissions are very heterogeneous along the study period, and the temporal trends are mainly driven by the changes in emission factors, energy intensity, economy, and population.

Investigation of mitigation of nitric oxide emission characteristics and slagging properties from biomass combustion by the additive of coal gangue

The co-combustion of coal gangue (CG) and biomass was expected to increase the utilization rate of solid waste and compensating for individual feedstock disadvantages. However, the emission of nitric oxide (NO) and ash melting characteristics during this process was of concern, but no relevant study had focused on this. In this work, the combustion behavior of Salix limb(SL)/Wheat straw(WS), CG and biomass-CG blends was studied by non-isothermal thermogravimetry and tube oven method. The results indicated that when CG was mixed into biomass fuel as an additive, the burn-out effect of CG was improved. The NO emissions from the experimental value of 80% SL/WS blend with 20% CG were reduced by 8.9%/10.1% compared to the theoretical value. Moreover, the potassium aluminum silicates with high melting temperatures were formed in the ash of the composite fuel, which reduced the serious slagging phenomenon that has been observed in the biomass combustion process. The composite fuel of 80% biomass (SL/WS) + 20% CG could promote combustion and reduce NO emissions, which was a meaningful method to treat CG to the maximum benefit and reduced the phenomenon of biomass slagging.

Water soluble reactive phosphate (SRP) in atmospheric particles over East Mediterranean: The importance of dust and biomass burning events

The importance of dust and biomass burning episodes on the atmospheric concentration of water-soluble reactive phosphate (SRP) was determined in the eastern Mediterranean. SRP was measured with a new rapid real-time automated analytical system with a time resolution of a few minutes per sample and with an extremely low detection limit. The average atmospheric concentration of SRP during the sampling campaign was estimated at 0.35 ± 0.25 (median 0.30) nmol P m−3. The maximum concentration of SRP (3.08 nmol P m−3) was recorded during an intense dust episode, and was almost ten times higher than the campaign average, confirming that Saharan dust was an important primary source of bioavailable P to the eastern Mediterranean, especially during the spring period when 60% of the events occurred. Predicted increases in the frequency and intensity of dust storms in the area will enhance the role of the atmosphere as a source of bioavailable P for the Mediterranean marine ecosystem. During the warm period, when Northerly winds prevailed, biomass burning processes contributed significantly to soluble phosphorus delivered from atmospheric sources to the eastern Mediterranean. These inputs during warm periods are especially important for the Eastern Mediterranean, where biological productivity is strongly limited by nutrient availability.

Three-dimensional modelling and optimization of an industrial dual fluidized bed biomass gasification decoupling combustion reactor

Dual fluidized bed biomass gasification decoupling combustion technology, as a promising technology to realizing the highly efficient and stable combustion for high-water-containing biomass fuel and lower NOx emission, has drawn worldwide attention from researchers in recent years. In this work, a three-dimensional industrial dual fluidized bed biomass gasification decoupling combustion reactor was modelled using the reactive multiphase particle-in-cell approach, and the secondary air operating parameters concerning total secondary air ratio, upper secondary air ratio, upper secondary air height, and upper secondary air injection models of the biomass gasification combustion reactor were optimized to enhance its performance further. Results show that the biomass gasification combustion model, established and comprehensively verified by comparing the simulated values with measured data in this work, shows a good prediction accuracy of gas–solid flow, heat transfer, and biomass combustion processes. With the total secondary air ratio, the upper secondary air ratio and the upper secondary air height increase, the gas-phase entrainment effects on the axial particle concentration distribution below the upper secondary air feed port in the dense zone weakens, and the overall biomass combustion efficiency decreases. Compared with the single injection model for the upper secondary air injection, the gas-phase entrainment effects on the axial particle concentration distribution were enhanced, and the overall biomass combustion efficiency was improved when adopting the opposite injection or circular injection model. Finally, the optimal secondary air operating parameters for the biomass gasification combustion reactor were obtained from the combustion and gasification views, providing an essential theoretical reference for industrial-scale dual fluidized bed biomass gasification decoupling combustion reactor optimization, biomass gasification decoupling combustion process enhancement, and efficient biomass energy utilization.