Abstract
Currently, the design of advanced moving grate (AMG) incinerators for solid waste is aided by computational simulations. The simulation approach couples a waste bed model to characterize the incineration processes of the waste material on top of the moving grate, with a computational fluid dynamics (CFD) model to reproduce the heated air movement and reactions in the incinerator space above. However, the simulation results of AMG incinerators are rarely compared with actual field measurements for validation in the literature so far. In this study, we first examine the sensitivity of pyrolysis kinetics in the waste bed model using three existing alternatives. The predictions of combustion characteristics, including the bed height, flow and temperature distributions, composition of stack gases and gas emissions are obtained for the three alternatives and compared with measurements from a simple laboratory furnace. The results show that the pyrolysis kinetics mechanism can significantly affect the outputs from the waste bed model for incineration modelling. Subsequently, we propose a new coupling approach based on a recent AMG waste bed model (which includes the complex pyrolysis kinetics inside the waste bed on top of the moving grate) and the freeboard CFD simulations. The new approach is then used to predict the field performance of a large scale waste-to-energy (WTE) plant and the predictions are compared directly with the real measurements in various operational scenarios. The comparison shows an overall satisfactory agreement in terms of temperature and exit gases composition given the complexity of the real life operations, although the CO emission is slightly underpredicted.
Highlights
Sustainable waste management is of critical importance worldwide and for the developing countries in Asia [1,2,3,4,5]
The results show that both the temperature and gas emissions from the furnace are sensitive to pyrolysis kinetics
The unknown Reynolds stress term in the Reynolds-averaged Navier–Stokes (RANS) equation was computed with the eddy viscosity, μt, solved by the RNG k-ε turbulence closure through two equations corresponding to turbulence kinetic energy (k) and the rate of the dissipation of turbulence energy (ε), respectively
Summary
Sustainable waste management is of critical importance worldwide and for the developing countries in Asia [1,2,3,4,5]. AAmmoonngg tthhee vvaarriioouuss ttyyppeess ooff ssoolliidd wwaassttee iinncciinneerraattoorr nnoowwaaddaayyss,, tthhee aaddvvaanncceedd mmoovviinngg ggrraattee ((AAMMGG)) iinncciinneerraattoorr iiss tthhee mmoosstt ccoommmmoonn cchhooiiccee. CCoommppuuttaattiioonnaall ssiimmuullaattiioonnss hhaavvee bbeeeenn uusseedd ttoo pprreeddiicctt tthhee ppeerrffoorrmmaannccee ooff AAMMGG iinncciinneerraattoorrss ffoorr ddeessiiggnn iimmpprroovveemmeenntt aanndd vveerriiffiiccaattiioonn. With respect to the freeboard CFD simulations, various approaches have been reported in previous studies using different turbulence closures and turbulence/reaction modelling methods [8,11,21,22,23,24]. We propose a new approach for the AMG incinerator modelling by coupling the AMG waste bed model developed recently by [27] (which includes the complex pyrolysis kinetics inside the waste bed on top of the moving grate) and the freeboard CFD simulations. The study represents the rare reporting of the comparison between the computational predictions and field measurements from a prototype large scale WTE facility for validation
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