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- W2890849698 abstract "This paper presents a comprehensive review on the development of the modelling of ash deposition with particle combustion, sticking, rebound and removal behaviors. The modelling of ash deposit morphomology is also included. Ash deposition in coal and biomass fired boilers will induce many ash-related issues (such as slagging, fouling and corrosion) which will reduce the boiler efficiency and capacity. Some traditional prediction methods have been proposed to evaluate ash deposition. However, these methods are based on chemical compositions of ash deposits and the operating temperatures in boilers, which are unable to fully predict the complex ash deposition process. Great efforts have been made to develop mechanistic models to predict ash deposition processes in nature. The behavior of ash formation and deposition in the boilers plays a key role in the design of boilers and the selection of fuels. The ash formation process is primarily due to the fragmentation and coalescence of mineral matters in fuels and only a small portion of ash is formed. When ash particles impact the heat transfer surfaces, only a few particles will deposit on these surfaces and several ash deposition mechanisms have been identified to predict their behaviors, such as inertial impaction (for large particles), thermophoresis (for fine particles) and condensation (for vapors). The ash deposition mechanisms used in the experimental, numerical and mechanistic studies coupled with the fuels and investigated systems are summarized in this paper. Numerous attempts have been made to develop different models to overcome the shortcomings of traditional methods. As such, various numerical attempts have been made to predict the growth behavior of ash deposition in furnaces and boilers by employing comprehensive combustion models coupled with high fidelity computational fluid dynamics (CFD) modelling methods for different types of fuels. Furthermore, several combustion codes have been incorporated into the ash deposition models, including the fuel combustion process (the release of volatiles, devolatilization and char combustion), wall reaction and consumption sub-models as well as the packed bed and overbed combustion sub-models. Moreover, several ash deposition sub-models have been developed to predict the ash deposition growth behavior using computational fluid dynamics (CFD) methods in combustors of different scales. In order to better understand the impact behavior of ash particles, some analytical models such as dynamic models and kinetic models have been developed. For accurate prediction of impaction efficiency, an impaction correction factor has been proposed to reduce the effect of coarse meshes on the impaction efficiency. Also, the stickiness of ash particles which is determined by kinetic energy, viscosity and molten degree of ash particles plays a key role in the ash formation and deposition processes and determines whether ash particles stick on the surfaces or rebound from the surfaces. Briefly, three main types of particle adhesion theories are used to evaluate if an impacting particle bounces off or sticks to the surface, namely, the viscosity-based empirical model, the critical velocity model and the melt fraction model. When the particles impact the heat transfer surfaces, they may rebound from the surface or remove the ash deposit. The particle surface energy with its static contact angle is also important in determining the sticking efficiency. In addition, several rebound criteria have been proposed to predict the particle rebound behavior, which include the critical rebound velocity, energy balance, excess energy, bouncing potential and critical impact angle on a flat or oblique plate or on a heat transfer tube. Tremendous efforts have also been made to develop the theories and mechanisms of ash deposition as well as removal on the surfaces of heat exchangers, some of which were based on the Kern-Seaton theory. Furthermore, several removal sub-models have been proposed to predict the particle removal behavior, including the energy balance, moment conservation, energy dissipation, critical moment theory, critical shear velocity and critical impact angle. In the actual fouling process, the growth behavior of fouling on the tube surfaces changes the original tube shape continuously. The fly ash deposited on the surface alters the boundary of heat transfer and affects the distribution of the temperature, flow field as well as the deposition rates. Various theoretical methods have been proposed to predict the ash deposit morphology, including the lattice Boltzmann method (LBM), dynamic meshing method, and time and mass magnification factors. In addition, many investigations have focused on developing models for inter-particle thermal conductivity by studying the ash deposit microstructure to characterize the thermal and morphological changes through an ash deposit. Several ash deposition layer models have been experimentally and theorectically studied in details, including the two-layer, three-layer, four-layer and six-layer sub-models." @default.
- W2890849698 created "2018-09-27" @default.
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- W2890849698 date "2018-11-01" @default.
- W2890849698 modified "2023-10-11" @default.
- W2890849698 title "Modeling of ash formation and deposition processes in coal and biomass fired boilers: A comprehensive review" @default.
- W2890849698 cites W1519505193 @default.
- W2890849698 cites W1535190853 @default.
- W2890849698 cites W1546531301 @default.
- W2890849698 cites W1561833587 @default.
- W2890849698 cites W1657108523 @default.
- W2890849698 cites W1669006332 @default.
- W2890849698 cites W1702963157 @default.
- W2890849698 cites W1813576013 @default.
- W2890849698 cites W1817445719 @default.
- W2890849698 cites W1856997086 @default.
- W2890849698 cites W188321684 @default.
- W2890849698 cites W1964084113 @default.
- W2890849698 cites W1964500472 @default.
- W2890849698 cites W1966167461 @default.
- W2890849698 cites W1966174025 @default.
- W2890849698 cites W1966253832 @default.
- W2890849698 cites W1966524821 @default.
- W2890849698 cites W1969065734 @default.
- W2890849698 cites W1969072689 @default.
- W2890849698 cites W1970582229 @default.
- W2890849698 cites W1970801361 @default.
- W2890849698 cites W1970957327 @default.
- W2890849698 cites W1970994002 @default.
- W2890849698 cites W1971137917 @default.
- W2890849698 cites W1972064878 @default.
- W2890849698 cites W1972262958 @default.
- W2890849698 cites W1973504304 @default.
- W2890849698 cites W1974428016 @default.
- W2890849698 cites W1975454471 @default.
- W2890849698 cites W1975929515 @default.
- W2890849698 cites W1977103689 @default.
- W2890849698 cites W1979131668 @default.
- W2890849698 cites W1979334207 @default.
- W2890849698 cites W1980064454 @default.
- W2890849698 cites W1980144028 @default.
- W2890849698 cites W198028628 @default.
- W2890849698 cites W1981433174 @default.
- W2890849698 cites W1981718790 @default.
- W2890849698 cites W1981722681 @default.
- W2890849698 cites W1981981279 @default.
- W2890849698 cites W1982242228 @default.
- W2890849698 cites W1982431988 @default.
- W2890849698 cites W1982504001 @default.
- W2890849698 cites W1982981654 @default.
- W2890849698 cites W1983044561 @default.
- W2890849698 cites W1983295584 @default.
- W2890849698 cites W1983631084 @default.
- W2890849698 cites W1984430829 @default.
- W2890849698 cites W1984701822 @default.
- W2890849698 cites W1984818481 @default.
- W2890849698 cites W1987096487 @default.
- W2890849698 cites W1987207564 @default.
- W2890849698 cites W1987676528 @default.
- W2890849698 cites W1988524963 @default.
- W2890849698 cites W1989698972 @default.
- W2890849698 cites W1990650978 @default.
- W2890849698 cites W1990838950 @default.
- W2890849698 cites W1991692939 @default.
- W2890849698 cites W1993145840 @default.
- W2890849698 cites W1994355389 @default.
- W2890849698 cites W1994602482 @default.
- W2890849698 cites W1994687619 @default.
- W2890849698 cites W1995037671 @default.
- W2890849698 cites W1995184762 @default.
- W2890849698 cites W1995872576 @default.
- W2890849698 cites W1996999616 @default.
- W2890849698 cites W1997446009 @default.
- W2890849698 cites W1998577540 @default.
- W2890849698 cites W1998774108 @default.
- W2890849698 cites W1999909706 @default.
- W2890849698 cites W2000745217 @default.
- W2890849698 cites W2000790687 @default.
- W2890849698 cites W2001502069 @default.
- W2890849698 cites W2001556622 @default.
- W2890849698 cites W2002343655 @default.
- W2890849698 cites W2003182915 @default.
- W2890849698 cites W2003341064 @default.
- W2890849698 cites W2003935924 @default.
- W2890849698 cites W2004117423 @default.
- W2890849698 cites W2004564760 @default.
- W2890849698 cites W2004929164 @default.
- W2890849698 cites W2005146570 @default.
- W2890849698 cites W2005598410 @default.
- W2890849698 cites W2006080689 @default.