Three-dimensional Simulation of Flow and Combustion for Pulverised Coal Injection

Abstract

A three-dimensional numerical model of pulverised coal injection has been developed for simulating coal flow and combustion in the tuyere and raceway of a blast furnace. The model has been used to simulate previously reported combustion tests, which feature an inclined co-axial lance with an annular cooling gas. The predicted coal burnout agrees well with that measured for three coals with volatile contents and particle size ranging between 20.2-36.4 % and particle sizes 1-200 mm. Many important phenomena including flow asymmetry, recirculating flow and particle dispersion in the combustion chamber have been predicted. The current model can reproduce the experimental observations including the effects on burnout of coal flowrate and the introduction of methane for lance cooling.

Three-dimensional Modelling of Coal Combustion in Blast Furnace

“…Figure 15 shows more comparisons with the measurements, at a specific position downstream (925 mm from lance tip) under a wide-range of O/C ratio (atomic O-to-C) from 1.85-3.97 ( Table 8). The results indicate that, the final burnouts at that position predicted using the present and previous models appear similar, and they are both comparable to the measured data 17,33) at 925 mma sampling point far away from the lance tip. That is, the two model are both correct for the burnout prediction at this point, in spite of omitted char gasification reactions in the previous models.…”

“…To date, a few 3D studies have been reported in the literature. [13][14][15][16][17] Murai et al 13) and Goto et al 14) reported a 3D simulation for blowpipe and on this basis some lance arrangements were examined for co-injections of coal/plastic and coal/gas. Du et al 15) reported a model for blowpipe and tuyere.…”

“…This approach is interesting but difficult to be applied generally to a practical system where the number of particles is huge. Guo et al 17) recently reported a model for tuyere and raceway cavity, and demonstrated that the model can describe some typical phenomena of coal combustion. However, this model showed a limited capability, e.g.…”

Computational Fluid Dynamics (CFD) Modeling for High Rate Pulverized Coal Injection (PCI) into the Blast Furnace

“…More recently, commercial software was utilized to simulate coal de-volatilization and combustion in a combustion chamber [22] and in a tuyere-raceway system with an assumed raceway shape [23] . The particle phase was treated as a dispersed phase using a Lagrangian method and a stochastic model was used to calculate particle turbulent dispersion.…”

“…The heterogeneous char reaction rate is assumed to be of first-order with respect to oxygen, carbon dioxide and water vapor concentrations [22] .…”