A phenomenological investigation into potassium migration and ash sintering characteristics during p.f. combustion of lignites with and without K2CO3 addition

IET Renewable Power Gen

Zhu

et al. 2021

The high content of the AAEMs in Zhundong (ZD) coal causes easily slagging on the heating surface of boilers, and the addition of rice husk hydrochar (RHC) is expected to alleviate slagging by introducing SiO2 content. ZD coal is co‐fired with RHC according to different blend ratios, co‐combustion ashes are prepared subsequently at different temperatures. The co‐combustion characteristics of blends are studied firstly by using TGA, considering the combustion process can bring impacts on ash characteristics. Then the effects of the blend ratio and ashing temperature on the ash characteristics are discussed. The ash samples are characterized by XRF, ICP‐AES, XRD and SEM. The results show that an increase in the blend ratio of the RHC reduces the ignition temperature and lengthens the burnout time, which transforms the ash characteristics. The contents of quartz, gehlenite and andalusite greatly increase. The number of fine particles in the ash decreases, while the particle size increases. The ash fusion temperatures (AFTs) are at the lowest value at 8:2 and exceed totally that of ZD coal at 7:3. Considering to increase the AFTs of ZD coal, at least the blend ratio of 7:3 of ZD coal and RHC is recommended for co‐combustion.

Section: Microstructural Characteristics Of the Ash From The Blends O...mentioning

confidence: 99%

Co‐combustion and ash characteristics of Zhundong coal with rice husk hydrochar prepared by the hydrothermal carbonization technology for co‐combustion

IET Renewable Power Gen

Zhu

et al. 2021

“…The unreacted silica particles are in the shape of a cube, while reacted silica particles obtained at the gasification temperatures of 650℃ and 750℃ show folds and micropores on the particle surface respectively. It is indicated that temperature can affect the morphology and size of ash particulates [39].Nevertheless, as shown in Fig. 5(b,c) and Fig.…”

Section: Sem-edx Analysis Of Reacted Samplesmentioning

confidence: 84%

“…Sintering phenomena is a heat-induced mass transport driven by the reduction of free surface energy kinetically controlled by temperature in a particle bed [37].Once sintering occurs in the process of ash deposition, the deposited ash particles are gradually sintered together, and the particle size and strength increase gradually, eventually forming sintered or molten sediments [38].The performance of simulated ash was investigated qualitatively by comparing the morphology change of unreacted silica and reacted silica particles with and without CaO at different temperatures.…”

Section: Sem-edx Analysis Of Reacted Samplesmentioning

confidence: 99%

Autothermal CaO looping biomass gasification to increase process energy efficiency and reduce ash sintering

Zhang

Gao

et al. 2020

Fuel

Biomass gasification is considered as a promising renewable energy technology to address climate change caused by greenhouse gas emissions and produce portable and clean energy products. However, biomass must be combusted in the traditional gasification to maintain the process, while excessive gasification temperature will lead to ash sintering, resulting in the shutdown of the equipment. Autothermal biomass gasification is directly maintained by carbonation reaction, which can maximize the production of combustible gas and reuse carbon dioxide in the flue gas. Lab-scale results indicated that similar H2 yield can be obtained via Auto-CaL-Gas technology at lower operating temperatures. Moreover, H2 concentration increased by 23.29% at 650℃with CaO than at 750℃ without CaO, and 14.11% at 550℃ with CaO than at 650℃ without CaO, respectively, thus saving energy consumption and improving total energy efficiency in the biomass gasification process.

“…The general law of porous structural transformation during sintering can be obtained by combining the pore parameters with the degree of ash agglomeration ,, (Section ). During the beginning stage of sintering, as shown in Figure , a large number of small pores were generated, and the total pore number increased rapidly.…”

Section: Resultsmentioning

confidence: 99%

Experimental Study of the Pore Structure during Coal and Biomass Ash Sintering Based on X-ray CT Technology

Zhou

et al. 2021

Energy Fuels

This paper explores the evolution of pore structure parameters during Zhundong coal and biomass ash sintering at 1473 K. Additionally, the influences of blending biomass ash with different proportions are determined. The pore parameters, including the porosity, diameter, number, and frequency of the equivalent diameter, were processed by reconstructing and processing three-dimensional (3D) data on the basis of X-ray computed microtomography (XCT). The maximum porosities for the cases of pure coal and mixture of 10% biomass and 50% biomass during sintering are determined to be 46.6, 42.6, and 24.0%, respectively, while the frequencies of small pores (<0.2 mm) in the coal ash samples are lower than those in the other cases. In addition, the mineralogical phase transformation during sintering is identified by X-ray diffraction analysis. The condensate in the pores mainly comprises NaCl, CaSO 4 , and KCl, which indicates that the volatilization of alkali metals and the formation and gasification of anhydrite occur throughout the sintering process.