Ash Fusion Characteristics and Transformation Behaviors during Bamboo Combustion in Comparison with Straw and Poplar

Abstract

In this work, the bamboo ash fusion and sintering characteristics were studied to evaluate its potential application in combustion for the production of heat and power. Poplar and wheat straw were used in the experimental test as the reference fuels for comparison. Standard ash fusion tests and ash sintering tests were carried out at elevated temperatures. The results indicate that bamboo has a low ash melting temperature of 862 °C, much lower than that of poplar. In spite of the high K content in bamboo ash, no severe melting and sintering was observed under the temperature lower than 1000 °C. The ashes after the tests were analyzed using SEM/EDX, XRF, and XRD techniques to illustrate the ash transformation behavior. Standard ash fusion tests indicated that the melting temperatures of bamboo, wheat straw, and poplar ashes are 862 °C, 770 °C, and 1088 °C, respectively. No severe sintering can be observed for poplar due to the large existence of refractory compounds. Ash sintering occurred when the temperature is higher than 800 °C, for wheat straw, due to the formation of the low melting temperature K-rich silicate. Additionally, bamboo ash has a relatively high P content compared to that of wheat straw, which facilitates the formation of high melting temperature compounds of K–Ca/Mg phosphates. Moreover, the ash content in bamboo is low. As a conclusion, bamboo is a good quality biofuel which can be fired in biomass combustion plants without severe sintering at a temperature lower than 1000 °C.

Growing Poplar in Acid Soils: Biomass Yield and Ash Behavior

“…The study findings confirm that woody biomass produced from poplar does not undergo severe sintering during the combustion process [42]. This has been shown to be related to the high melting temperature of the ash and to the presence of large amounts of refractive compounds in the ash [43]. Nonetheless, the present findings show that K/Ca ratios may be higher than previously reported for poplar [44].…”

Physical, Chemical and Mechanical Properties of Two-Age Bambusa tuldoides Briquettes

“…Ash has an important implication on harvesting or industrial operations. Bamboo ash content varies according to species and management, equal to or less than 1% [22,23]. In the present study, where different bamboo ages were sampled, a higher ash content found is still within the limits described [24,25].…”

“…Also, increasing age led to a decrease in N, P, K, and Ca and increased Mg concentration. The relatively high value of P stands out for being considered an essential element due to its characteristic of facilitating the formation of high melting point K-Ca / Mg phosphate compounds, which, combined with the low ash content, would characterize bamboo as a promising biofuel for not presenting severe sintering at temperatures below 1000 °C [23].…”

“…According to Table 1, the HHV values found were slightly lower than those found in the literature. Considering data from several pieces of research, such as mean HHV values of 19.4 MJ kg -1 for Bambusa spp [23], mean HHV values between 19.09 and 19.57 MJ kg -1 for the species Phyllostachys nigra, Phyllostachys bambusoides, and Phyllostachys bissetii [22], and B. vulgaris with an average value of 19.12 MJ kg -1 , which are slightly below average [3]. On the other hand, it´s possible to track research data with HHV values closer to those of this study, 18.7 MJ kg -1 for B. tuldoides, and 17.6 MJ kg -1 for B. vulgaris [29].…”

Physical and chemical characterization of Chinese maize stalk leaf ash: Calcining temperature and aqueous solution

“…Silica, potassium oxide, magnesium oxide, and lime compounds were predominantly observed in the samples. The abundance of K in MSLA together with the high Si content favors the formation of alkali-rich silicates and thus decreases the ash melting temperature (Zhu et al 2018). Meanwhile, the contents of refractory species Mg, Ca, Fe, Al, Si, S, and P were nearly constant or slightly increased with temperature.…”