Figure 1 - available via license: CC BY
Content may be subject to copyright.
The batch-size pilot setup for experimental studies: 1-gasifier filled with a mixture of biomass pellets; 2-propane flame inlet nozzle; 3-primary air supply at the bottom of the gasifier; 4-secondary swirling air inlet at the combustor bottom; 5-water-cooled sections of the combustion chamber; 6-axially inserted central electrode; 7-openings the diagnostic tools. The technological scheme of main equipment and measurement instruments is available at Figure S2.
Source publication
The aim of this study was to provide more effective use of straw for energy production by co-firing wheat straw pellets with solid fuels (wood, peat pellets) under additional electric control of the combustion characteristics at thermo-chemical conversion of fuel mixtures. Effects of the DC electric field on the main combustion characteristics were...
Contexts in source publication
Context 1
... study the effects of the wheat straw co-firing with biomass pellets of different origin (wood or peat), a batch-size pilot setup with a heat output up to 4 kW has been developed. The experimental setup (Figure 1) consists of a cylindrical 88 Ø × 250 mm biomass gasifier (1), a propane burner (2), a primary air supply (3), a secondary swirling air supply (4) and two cylindrical 88 Ø × 600 mm water-cooled combustion chamber sections (5) and an axially inserted electrode (6). The batch-size pilot setup for experimental studies: 1-gasifier filled with a mixture of biomass pellets; 2-propane flame inlet nozzle; 3-primary air supply at the bottom of the gasifier; 4-secondary swirling air inlet at the combustor bottom; 5-water-cooled sections of the combustion chamber; 6-axially inserted central electrode; 7-openings the diagnostic tools. ...
Context 2
... thermochemical conversion of the biomass mixture lasted about 2600 s if straw is co-fired with wood pellets and about 3600 s if straw is co-fired with peat. The schematic diagram which describes the experiment is available at Figure S1. ...
Context 3
... air supply flowrate was estimated using Testo 6441 flowmeters (Testo SE & Co. KGaA, Lenzkirch, Germany) with an accuracy ± 3%. Figure 1. The batch-size pilot setup for experimental studies: 1-gasifier filled with a mixture of biomass pellets; 2-propane flame inlet nozzle; 3-primary air supply at the bottom of the gasifier; 4-secondary swirling air inlet at the combustor bottom; 5-water-cooled sections of the combustion chamber; 6-axially inserted central electrode; 7-openings the diagnostic tools. ...
Context 4
... thermochemical conversion of the biomass mixture lasted about 2600 s if straw is co-fired with wood pellets and about 3600 s if straw is co-fired with peat. The schematic diagram which describes the experiment is available at Figure S1. ...
Context 5
... complex measurements of the electric field effect on the formation of flow dynamics at co-firing of straw with wood or with peat pellets were provided for the positively bias voltage of the axially inserted electrode, which is inserted into the flame reaction zone at 130 mm from the secondary air supply nozzle (Figure 1), where the average flame temperature approaches to 1350K. For the given configuration of the electrode the electric body force acts on the positive flame ions enhancing the processes of radial and reverse axial heat/mass transfer. ...
Context 6
... complex measurements of the electric field effect on the formation of flow dynamics at cofiring of straw with wood or with peat pellets were provided for the positively bias voltage of the axially inserted electrode, which is inserted into the flame reaction zone at 130 mm from the secondary air supply nozzle (Figure 1), where the average flame temperature approaches to 1350K. For the given configuration of the electrode the electric body force acts on the positive flame ions enhancing the processes of radial and reverse axial heat/mass transfer. ...
Context 7
... the heat power of the device at the stage of self-sustained combustion keeps growing, the total produced heat per mass of burned solid fuel decreases after reaching its peak value at I = 1.9 mA at straw/wood co-firing and at I = 2.5 mA when co-firing straw and peat, which can be theoretically explained by the field-induced increase of the axial flow velocity and decrease of the air swirl intensity thus reducing the reaction residence time and by limiting mixing of the reactants (Figure 6). Finally, it should be noted however, that the field-enhanced thermo-chemical conversion of the mixtures affects the flue gas composition, increasing the carbon-neutral CO2 emission and combustion efficiency, whereas the air excess ratio in the products decreases to the minimum value, providing so the cleaner and more efficient heat production (Figure 10a,b). Finally, it should be noted however, that the field-enhanced thermo-chemical conversion of the mixtures affects the flue gas composition, increasing the carbon-neutral CO 2 emission and combustion efficiency, whereas the air excess ratio in the products decreases to the minimum value, providing so the cleaner and more efficient heat production (Figure 10a,b). ...
Context 8
... it should be noted however, that the field-enhanced thermo-chemical conversion of the mixtures affects the flue gas composition, increasing the carbon-neutral CO2 emission and combustion efficiency, whereas the air excess ratio in the products decreases to the minimum value, providing so the cleaner and more efficient heat production (Figure 10a,b). Finally, it should be noted however, that the field-enhanced thermo-chemical conversion of the mixtures affects the flue gas composition, increasing the carbon-neutral CO 2 emission and combustion efficiency, whereas the air excess ratio in the products decreases to the minimum value, providing so the cleaner and more efficient heat production (Figure 10a,b). Finally, it should be noted however, that the field-enhanced thermo-chemical conversion of the mixtures affects the flue gas composition, increasing the carbon-neutral CO2 emission and combustion efficiency, whereas the air excess ratio in the products decreases to the minimum value, providing so the cleaner and more efficient heat production (Figure 10a,b). ...
Context 9
... it should be noted however, that the field-enhanced thermo-chemical conversion of the mixtures affects the flue gas composition, increasing the carbon-neutral CO 2 emission and combustion efficiency, whereas the air excess ratio in the products decreases to the minimum value, providing so the cleaner and more efficient heat production (Figure 10a,b). Finally, it should be noted however, that the field-enhanced thermo-chemical conversion of the mixtures affects the flue gas composition, increasing the carbon-neutral CO2 emission and combustion efficiency, whereas the air excess ratio in the products decreases to the minimum value, providing so the cleaner and more efficient heat production (Figure 10a,b). Figure 10. ...
Context 10
... it should be noted however, that the field-enhanced thermo-chemical conversion of the mixtures affects the flue gas composition, increasing the carbon-neutral CO2 emission and combustion efficiency, whereas the air excess ratio in the products decreases to the minimum value, providing so the cleaner and more efficient heat production (Figure 10a,b). Figure 10. Electric field effect on the CO 2 volume fraction in flue gases when co-firing 30% straw with wood (a) or with peat (b) pellets. ...
Context 11
... development of the axial distribution of the radial velocity (0 < r < 1; 0 < x < 2) is illustrated in Figure 11. The radial velocity distribution on the z-axis at r = 0.5 demonstrates a strong decrease to negative values at the flame base z/R 0 = [0; 0.75], whereas at r = 0.75 this distribution shows the most pronounced value decrease at z/R 0 = [0. ...
Context 12
... development of the axial distribution of the radial velocity (0 < r < 1; 0 < x < 2) is illustrated in Figure 11. The radial velocity distribution on the z-axis at r = 0.5 demonstrates a strong decrease to negative values at the flame base z/R0 = [0; 0.75], whereas at r = 0.75 this distribution shows the most pronounced value decrease at z/R0 = [0. ...
Context 13
... with a correlating decrease in radially-averaged flow temperature (Table 2). In Figure 12, the represented temperature distribution in the combustion chamber section shows an increase of the maximum temperature Tmax at the center of the flame base z/R0 = [0; 1], which may occur due to the field induced radial motion of the reactants towards the center and their more complete burnout. However, the action of the Lorenz force at Pe > P0 leads to a decrease of the radiallyaverage flow temperature Tav, which can be accompanied by a decrease of the visible flame radius. ...
Context 14
... the action of the Lorenz force at Pe > P0 leads to a decrease of the radiallyaverage flow temperature Tav, which can be accompanied by a decrease of the visible flame radius. In Figure 12, the represented temperature distribution in the combustion chamber section shows an increase of the maximum temperature T max at the center of the flame base z/ R 0 = [0; 1], which may occur due to the field induced radial motion of the reactants towards the center and their more complete burnout. However, the action of the Lorenz force at P e > P 0 leads to a decrease of the radially-average flow temperature T av , which can be accompanied by a decrease of the visible flame radius. ...
Similar publications
Background: Emotional exhaustion, and reduced perception of personal accomplishment is commonly defined as burn out syndrome. This may develop when there is significant stress without adequate support and resources in the face of work overload, as commonly happens with physicians and undergraduate medical students.Methods: This work attempted to st...
Job burnout can reduce job performance. The present study aimed to investigate the job burnout syndrome and its effective factors among military personnel. In this cross-sectional study, 930 military personnel from different areas were selected via cluster sampling. For data collection, the job burnout questionnaire and the job description index we...
Frequent turnover of behavior technicians working with individuals with autism spectrum disorder (ASD) may have negative impacts on organizations, staff, and patients. The current paper set out to conduct a systematic review of predictors of staff retention in behavior technicians. Two databases were searched to identify studies relating to retenti...
Citations
... Peat pellets have been shown to be used as biofuel in co-firing applications to enhance the efficiency of energy production systems. Studies have explored the mechanisms of co-firing of solid fuels with wheat straw pellets under controlled combustion conditions, aiming to optimize energy production processes (Barmina et al., 2019). Moreover, hydrothermal carbonization of peat moss, either alone or co-processed with agricultural biomass like miscanthus, can lead to the production of hydrochar, which can then be pelletized to create densified biofuels (Roy et al., 2018). ...
Pellets derived from non-food biomass, like wood and agricultural residues, represent a promising second-generation biofuel. Pellet
based biofuels have the potential to offer a cleaner and environmentally friendly alternative to conventional fossil fuels. There are several variables that affect pellet quality, such as biomass feedstock properties, pelletization processes, and the proper application of the pre-treatment techniques. Pre-treatment techniques can vary to include pyrolysis or torrefaction. Several raw materials are proposed for pellet-based biomass, such as agricultural residue pellets, grass pellets, and composite pellets. This chapter demonstrated that wood-based pellets are the most commonly used. Moreover, specific tropical wood species like Acacia wrightii and Ebenopsis ebano exhibit high energy density and mechanical strength. This makes them suitable for industrial heating applications. This chapter showed the potential of pellets as a sustainable energy solution. More efforts should be directed toward refining pellet production processes and expanding pellet applications in various sectors, including residential heating, power generation, and large-scale industrial processes. This chapter concludes that the pellet industry contributes to a circular economy by providing biofuel while mitigating waste.
... Therefore, the gradual replacement of fossil fuels with different types of renewable fuels for energy production is considered as a promising tool to control global warming [2; 3]. To provide such replacement, combustion of different renewable solid fuels can be used in practical applications [4]. Combustion of biomass blends with wheat straw, which is a widespread biomass with a relatively high energy potential, is of high particular interest [5]. ...
... To control structural changes of pellets due to MW pre-treatment, change of the weight, variations of the surface area and porosity were measured. The higher heating value (HHV) of pre-treated pellets was estimated from measurements of their elemental composition by varying the pre-treatment regime using the methods which are described in [4]. ...
... The effects of MW pre-treatment regime of the wheat straw pellets and the composition of the fuel blends on kinetics and average values of the flame temperature, heat capacity and composition of emissions were studied using the thermocouples, Testo 350 gas analyser and calorimetric measurements of cooling the water flow of the device. Measurement methods and the estimated accuracy are described in detail in [4]. ...
... Two types of pilot-scale experimental devices were used to study the thermal decomposition and combustion processes of microwave-activated biomass pellets [17,18]. A microwave reactor was used for the pretreatment of different origin commercial pellets: wheat straw pellets with an average diameter of 8 mm and moisture content of 10.2%, wood (softwood) pellets with an average diameter of 6 mm and moisture content of 7.14%, and peat pellets with an average diameter of 8 mm and moisture content of 8.9%. ...
... A pilot device with an average heat capacity up to 5 kW, which combined a gasifier of biomass pellets and a combustor [18], was used to study the thermal decomposition and combustion of mw pretreated pellets ( Figure 1). The gasifier was filled with pretreated biomass pellets (340-500g); the thermal decomposition was initiated using additional heat supply by a propane flame flow into the upper part of the biomass layer and was supported using the primary air supply below the layer of biomass pellets at an average air supply rate of 40 L/min. ...
... The burnout of volatiles downstream of the combustor was enhanced using the secondary swirling air supply at an average air supply rate 60 L/min. The effect of mw pretreatment on the thermal decomposition of pretreated pellets and combustion of volatiles was estimated, providing the complex measurements of the kinetics of the weight loss rate of pretreated pellets and the yield of volatiles during their gasification (using the sampling procedure and a Testo 350 gas analyzer (Vietnam), kinetics of the flame temperature, heat output from the device and composition of emissions, using methodology described in [18]. ...
The objective of the study was to investigate a more effective use of commercially available biomass pellets (wheat straw, wood, peat) using microwave pretreatment to improve heat production. Pellets were pretreated using the originally designed microwave torrefaction device. The effects of microwave (mw) pretreatment were quantified, providing measurements of the weight loss and elemental composition of pellets and estimating the effect of mw pretreatment on their porosity, surface area and calorific values at pretreatment temperatures of T = 448–553 K. Obtained results show that the highest structural variations and elemental composition during mw pretreatment were obtained for wheat straw pellets, with an increase in reactivity, a decreasing in the duration of the thermal decomposition by about 40% and an increase in the yield of combustible volatiles. Increased reactivity of pretreated pellets enhanced the ignition and burnout of volatiles, decreasing the duration of the burnout of pretreated wheat straw, wood and peat pellets by 40%, 24% and 9%, respectively, and increasing the peak and average values of the flame temperature, heat output, and produced heat energy by 40–50%, with a correlating increase of combustion efficiency and the mass fraction of carbon-neutral CO2 emission. Thus, the applicability of microwave pretreatment for the control and improvement of heat production was confirmed.
... However, the use of renewable sources, especially agricultural or herbaceous residues, for energy production is limited by their low calorific value, high moisture, nitrogen and ash contents in biomass [3]. Combined processes of biomass thermochemical conversion are developed to improve the main combustion characteristics and the composition of the products by co-firing of problematic biomass fuels (agricultural or herbaceous residues) with wood [3; 4] or fossil fuels (gaseous, coal or peat) [5][6][7]. Moreover, biomass characteristics can be improved by washing, drying, granulation or conversion of biomass into biogas or bioethanol. ...
... The effect of mw pre-treatment on thermochemical conversion of biomass pellets (wood, peat, wheat straw) was studied using the small-scale periodic operation experimental setup with a heat output up to 5 kW and the previously developed methodology of experimental measurements [7]. The main components of the setup: a biomass gasifier, two vertical and one T-shaped water-cooled sections of the combustor with the inner diameter D = 88 mm. ...
... Barmina et al. [144] studied the electric field effect on the thermal decomposition and co-combustion of straw with solid fuel pellets. The fixed bed experimental setup with a heat output of 4 kW was used. ...
The strong demand for sustainable energy supplies had escalated the discovery, and intensive research into cleaner energy sources, as well as efficient energy management practices. In the context of the circular economy, the efforts target not only the optimisation of resource utilisation at various stages, but the products’ eco-design is also emphasized to extend their life spans. Based on the concept of comprehensive circular integration, this review discusses the roles of Process Integration approaches, renewable energy sources utilisation and design modifications in addressing the process of energy and exergy efficiency improvement. The primary focus is to enhance the economic and environmental performance through process analysis, modelling and optimisation. The paper is categorised into sections to show the contribution of each aspect clearly, namely: (a) Design and numerical study for innovative energy-efficient technologies; (b) Process Integration—heat and power; (c) Process energy efficiency or emissions analysis; (d) Optimisation of renewable energy resources supply chain. Each section is assessed based on the latest contribution of this journal’s Special Issue from the 21st conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction (PRES 2018). The key results are highlighted and summarised within the broader context of the state of the art development.
The Doctoral Thesis examines the control of the swirling flame flow dynamics with an external static electric field by firing the gaseous products of thermal decomposition of pelletized straw, woody biomass, and peat with the aim of more efficient heat production with a decrease of flue gas emissions. The intensification of the downward vortex in the electric field has been determined, ensuring improved mixing of the air vortex with the biomass thermal decomposition gas flow, intensifying the convective mass transfer towards the heating surfaces, and increasing the amount of heat energy produced in the biomass thermochemical conversion process.
With the aim to control and improve the thermo-chemical conversion of straw pellets, the experimental investigations of the DC electric field effect on the combustion dynamics and heat energy production were made. The electric field effect on the gasification/combustion characteristics was studied using three different positions of the positively charged electrode in flame. First, the electrode was positioned coaxially downstream the flame flow. Next, the electrode was positioned coaxially upstream the flame flow and, finally, the electrode was positioned across the downstream flow. The bias voltage of the electrode varied in the range from 0.6 up to 1.8 kV, while the ion current in flame was limited to 5 mA. The results of experimental investigations show that the DC electric field intensifies the thermal decomposition of straw pellets and enhances mixing of volatiles with air causing changes in combustion dynamics and heat energy production, which depend on position and the bias voltage of the electrode. The increase in the average volume fraction of CO2 (by 6 %) and the decrease in the mass fraction of unburned volatiles in the products (CO by 60 % and H2 by 73 %) for the upstream field configuration of the electrode and the ion current 0.5–1.8 mA indicate more complete combustion of volatiles.