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Normalized mass loss versus temperature during pyrolysis process of rice straw, coal and mixture-dry basis.
Source publication
Vietnam as an agricultural country has a high potential in biomass, especially agricultural and forestry wastes. This resource offers a promising way to develop co – combustion technology of biomass and coal in Vietnam and thus tackle the environmental issues. A fundamental research was established to study combustion of Vietnamese rice straw and c...
Contexts in source publication
Context 1
... Figure 3 and Figure 4 show respectively normalized mass loss (TG curve) and derivative mass loss (DTG curve) of rice straw, coal and their mixture during pyrolysis process under N 2 atmosphere. Because of its low volatile matters, the coal DTG was much lower than the one of rice straw and the mixture. Note that the derivative mass of coal in the Figure 4 has been multiplied by 10 to facilitate the reading. The char yield of rice straw (22.8 %) is significantly lower than coal's one (92.3 %). The reason is obviously the very high difference in volatile matters content. The char yield of rice straw/coal mixture is 57%. This char yield of the mixture is equivalent to the weighted sum of the char yield of the two constitutive solid fuels. The maximum mass loss is measured at low temperature for rice straw (T DTG max = 308°C) and for mixture (T DTG max = 307°C), and at higher temperature for coal (T DTG max = 480 and 627 °C). The pyrolysis of rice straw and mixture occurs in a narrow temperature range compared to the pyrolysis of coal. Moreover, the rice straw pyrolysis starts at a lower temperature than the blends pyrolysis. It seems that the presence of coal in the mixture delays the reaction. The temperature T DTG max and the derivative mass loss of each sample are summarized in the Table ...
Context 2
... Figure 3 and Figure 4 show respectively normalized mass loss (TG curve) and derivative mass loss (DTG curve) of rice straw, coal and their mixture during pyrolysis process under N 2 atmosphere. Because of its low volatile matters, the coal DTG was much lower than the one of rice straw and the mixture. ...
Citations
... (a) the first loss of 11% due to moisture removal, meaning the presence of significant hydrophilic functional groups until 148 • C [58]; (b) the loss of 47.9% up to 400 • C and 16.4% up to 500 • C due to the removal of volatile materials (principally hemicellulose and cellulose, respectively); and (c) the pyrolysis of the more stable lignins in the range of 500-600 • C with a loss of 8.0%; this high thermal stability of lignin may be due to the formation of pseudolignin [59]. Also, the pyrolysis of char produced from the thermal degradation of pectins and hemicelluloses may be involved in this loss of weight [60]. The pyrolysis analysis was over at 850 • C with a low weight loss of 6.7%. ...
A new biosorbent obtained from Calabrese broccoli stalks has been prepared, characterised and used as an effective, low-cost and ecofriendly biomass to remove Pb(II) from aqueous solutions, without any complicated pretreatment. Structural and morphological characterisation were performed by TGA/DGT, FTIR and SEM/EDX; the main components are hemicellulose, starches, pectin, cellulose, lignin and phytochemicals, with important electron donor elements (such as S from glucosinolates of broccoli) involved in Pb(II) sorption. The biosorbent showed values of 0.52 and 0.65 g mL−1 for bulk and apparent densities, 20.6% porosity, a specific surface area of 15.3 m2 g−1, pHpzc 6.25, iodine capacity of 619 mg g−1 and a cation exchange capacity of 30.7 cmol kg−1. Very good sorption (88.3 ± 0.8%) occurred at pH 4.8 with a biomass dose of 10 g L−1 after 8 h. The Freundlich and Dubinin–Radushkevich isotherms and the pseudo-second-order kinetic models explained with good fits the favourable Pb(II) sorption on the heterogeneous surface of broccoli biomass. The maximum adsorption capacity was 586.7 mg g−1. The thermodynamic parameters evaluated showed the endothermic and spontaneous nature of the Pb(II) biosorption. The chemical mechanisms mainly involved complexation, ligand exchange and cation–π interaction, with possible precipitation.
... In the lower temperature range, the blend thermal behavior closes to biomass and in the higher temperature region, it is similar to coal. Hoang Anh Tran et al [8] investigated the combustion of Vietnam rice straw, coal and their blends in a macro TG reactor and found that there is a coupling phenomenon between pyrolysis and char oxidation when blending two solid fuels. ...
... There is a significant reduction in the T max , and T b compared to in the case of the only char oxidation. This could be explained by the oxidation of volatiles released in the devolatization process, resulted in an increase of particle temperature and an acceleration of the char oxidation at lower temperature [6,8]. There was nearly no change of mass yield in the temperature range of 550-900 °C for both samples. ...
This work focused on investigating the thermal behavior of the coniferous tree (beech) and broadleaf tree (beefwood) that are abundantly available in Vietnam during a low-oxygen combustion condition. Pyrolysis in 100% Nitrogen atmosphere, char oxidation and combustion in 3% Oxygen atmosphere were conducted using a Macro-thermogravimetric analyzer, from room temperature to 900 o C. Results showed that, regarding pyrolysis and char oxidation processes, beech biomass has the initial mass loss and the maximum mass loss at higher temperatures compared to beefwood biomass. For the overall combustion process, two stages could be clearly observed in differential thermal analysis curves, which correspond to devolatilization and char oxidation. However, the maximum combustion rate temperature and the char burnout temperature were sharply lower than in the case of pyrolysis and char oxidation that were carried out independently. This is likely due to volatile combustion of gaseous products released in devolatilization that could lead to an increase of the particle temperature and an acceleration of the pyrolysis and char oxidation kinetics. This highlighted the synergistic effects of pyrolysis and char oxidation in the overall combustion process. Results of this study could contribute to the understanding of the combustion profile of these kinds of biomass in a low oxygen atmosphere, in order to better organize the furnace combustion and effectively improve the efficiency of coal/biomass combustion.
... In the lower temperature range, the blend thermal behavior closes to biomass and in the higher temperature region, it is similar to coal. Hoang Anh Tran et al [8] investigated the combustion of Vietnam rice straw, coal and their blends in a macro TG reactor and found that there is a coupling phenomenon between pyrolysis and char oxidation when blending two solid fuels. ...
... There is a significant reduction in the T max , and T b compared to in the case of the only char oxidation. This could be explained by the oxidation of volatiles released in the devolatization process, resulted in an increase of particle temperature and an acceleration of the char oxidation at lower temperature [6,8]. There was nearly no change of mass yield in the temperature range of 550-900 °C for both samples. ...
This work focused on investigating the thermal behavior of the coniferous tree (beech) and broadleaf tree (beefwood) that are abundantly available in Vietnam during a low-oxygen combustion condition. Pyrolysis in 100% Nitrogen atmosphere, char oxidation and combustion in 3% Oxygen atmosphere were conducted using a Macro-thermogravimetric analyzer, from room temperature to 900 o C. Results showed that, regarding pyrolysis and char oxidation processes, beech biomass has the initial mass loss and the maximum mass loss at higher temperatures compared to beefwood biomass. For the overall combustion process, two stages could be clearly observed in differential thermal analysis curves, which correspond to devolatilization and char oxidation. However, the maximum combustion rate temperature and the char burnout temperature were sharply lower than in the case of pyrolysis and char oxidation that were carried out independently. This is likely due to volatile combustion of gaseous products released in devolatilization that could lead to an increase of the particle temperature and an acceleration of the pyrolysis and char oxidation kinetics. This highlighted the synergistic effects of pyrolysis and char oxidation in the overall combustion process. Results of this study could contribute to the understanding of the combustion profile of these kinds of biomass in a low oxygen atmosphere, in order to better organize the furnace combustion and effectively improve the efficiency of coal/biomass combustion.
... In the lower temperature range, the blend thermal behavior closes to biomass and in the higher temperature region, it is similar to coal. Hoang Anh Tran et al [8] investigated the combustion of Vietnam rice straw, coal and their blends in a macro TG reactor and found that there is a coupling phenomenon between pyrolysis and char oxidation when blending two solid fuels. ...
... There is a significant reduction in the T max , and T b compared to in the case of the only char oxidation. This could be explained by the oxidation of volatiles released in the devolatization process, resulted in an increase of particle temperature and an acceleration of the char oxidation at lower temperature [6,8]. There was nearly no change of mass yield in the temperature range of 550-900 °C for both samples. ...
This work focused on investigating the thermal behavior of the coniferous tree (beech) and broadleaf tree (beefwood) that are abundantly available in Vietnam during a low-oxygen combustion condition. Pyrolysis in 100% Nitrogen atmosphere, char oxidation and combustion in 3% Oxygen atmosphere were conducted using a Macro-thermogravimetric analyzer, from room temperature to 900 o C. Results showed that, regarding pyrolysis and char oxidation processes, beech biomass has the initial mass loss and the maximum mass loss at higher temperatures compared to beefwood biomass. For the overall combustion process, two stages could be clearly observed in differential thermal analysis curves, which correspond to devolatilization and char oxidation. However, the maximum combustion rate temperature and the char burnout temperature were sharply lower than in the case of pyrolysis and char oxidation that were carried out independently. This is likely due to volatile combustion of gaseous products released in devolatilization that could lead to an increase of the particle temperature and an acceleration of the pyrolysis and char oxidation kinetics. This highlighted the synergistic effects of pyrolysis and char oxidation in the overall combustion process. Results of this study could contribute to the understanding of the combustion profile of these kinds of biomass in a low oxygen atmosphere, in order to better organize the furnace combustion and effectively improve the efficiency of coal/biomass combustion.
... [9] The synergistic effects when blending two solid fuels were also observed. [10] Air pollution from the system is also mitigated. [7] Despite these advantages, several issues in current technologies still exist, such as low thermal efficiency, heat load instability, slagging. ...
In the context of sustainable development, co‐gasification or co‐firing of biomass residues and coal is becoming a relevant solution to mitigate the negative impact of fossil fuels. For this reason, it is crucial to understand the characteristics, as well as the thermal behaviors of these residues, especially in a low‐oxygen condition that is often found in industrial processes. In this study, woody residues, namely bamboo and rubberwood chips that are abundantly available in Vietnam were characterized. Thermal degradation of these residues in 4 % oxygen was also conducted using a Macro‐thermogravimetric analyzer, from room temperature to 700 °C. The results showed that bamboo had a higher volatile matter and a higher hemicellulose content compared to rubberwood chips, hence is easier for ignition in a thermochemical conversion process. Regarding the thermal behaviors of these residues in a reduced‐oxygen condition, three stages could be clearly observed in the TGA‐DTG curves. Rubberwood chip had a higher ignition temperature and higher temperatures of maximum mass loss rate compared to bamboo chip. Results could contribute to the understanding of the thermal behaviors of these biomass feedstocks in order to improve the efficiency of co‐gasification or co‐firing processes.
