Abstract
This publication considers the numerical simulation of
flow,
combustion, heat transfer and nitrogen pollutants in
furnaces.
The main emphasis is on the presentation and application
of a
computational environment for pulverized fuel (and spray)
combustion in multi-burner furnaces. The submodels of the
computational environment include the (k,epsilon)-model
and a
multiple-time-scale model of turbulence, the eddy breakup
and eddy
dissipation concepts for gaseous combustion, a stochastic
Lagrangian description of particles, a flux method and a
variant
of the discrete transfer method for radiative heat
transfer, and
reduced schemes for the formation and destruction of
nitric
oxide. The flow equations are solved with the
Phoenics-program of
CHAM Ltd, to which a technique to refine the
computational grid
locally has been added by the author.
Three applications are presented. In the simulation of
the
combustion of light fuel oil in a 300 kW furnace and of
pulverized
peat in a 5 MW furnace only some of the submodels have
been used.
The computed results of these two applications agree well
with the
experiments in the far field region of the furnace and
for the
overall features. The agreement in the near burner regime
is only
satisfactory. The qualitatively different behaviour of
the
combustion of pulverized peat under various firing
conditions
could also be simulated. The computation of the
combustion of
pulverized coal in a 250 MW boiler furnace under various
firing
conditions showed the applicability of the submodels to a
multi-burner furnace. The computed results are in
reasonable
agreement with the available measurements at the exit of
the boiler
furnace for temperature, char burnout and the
concentration of
nitric oxide. The principal factors related to the
submodels, to the
boundary conditions and to the discretizations, which
affect the
accuracy of the computed results, are discussed. Expected
development of submodels and computing techniques are
briefly
considered. The results obtained indicate that, properly
used, the
present submodels and computing power are already
capable of
providing a useful insight into the local conditions in
the
furnace. Such an insight is needed e.g. for a successful
application
of in-furnace methods to reduce nitrogen pollutants.
Original language | English |
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Qualification | Doctor Degree |
Awarding Institution |
|
Award date | 10 Dec 1993 |
Place of Publication | Espoo |
Publisher | |
Print ISBNs | 951-38-4397-1 |
Publication status | Published - 1993 |
MoE publication type | G4 Doctoral dissertation (monograph) |
Keywords
- combustion
- furnaces
- emissions
- pollutants
- air pollution
- nitrogen oxides
- numerical analysis
- simulation