Page 53 - Materials Chemistry, Second Edition

L1644_C01.fm Page 29 Monday, October 20, 2003 11:46 AM

TABLE 1.2 (CONTINUED)
Overview of Data from the MSWI Plant in Tarragona, Spain

Without new
Situation filters With new filters

Longitude (∞) d 1.211 1.211
Terrain elevation (m) 90 90
a Corresponds to the measured value, not to the adjusted one used in the LCA
study (see Chapter 2).
b Heavy metals is a sum parameter in the form of Pb equivalents of the following
heavy metals: As, B, Cr, Cu, Hg, Mn, Mo, Ni, Pb, and Sb. Cd is considered apart
for its toxic relevance and As and Ni for their carcinogenic relevance.
c Although there are two stacks with 1.4 m, due to the limitations of the dispersion
models used, one stack with a diameter of 1.98 was considered.
d Initially the data were in UTM, the Mercator transversal projection. The
conversion was made using the algorithm in http://www.dwap.co.uk/welcome.
;
ronmental Management and Analysis (AGA) Group of the Universitat Rovira i Virgili
in Tarragona, Spain. The MS–Excel-based model takes into account the elementary
waste input composition and relevant plant data, such as plant layout and process
specific constants.
In the model, the steam generator consists of grate firing and heat recovery
systems and a regenerative air preheater. Energy production is calculated using the
heating value of the waste input and the state points of the steam utilization process.
For the macroelements (C, H, N, O, S and Cl, F), the flue gas composition is
determined by simple thermodynamic calculation of the combustion, taking excess
air into account. The heavy metals, however, are calculated on the basis of transfer
coefficients (Kremer et al., 1998). Emissions of CO and TOC depend on the amount
of flue gas. For the emissions of NO and PCDD/Fs, empirical formulas are used.
x
Because acid-forming substances like S, Cl, and F are partly absorbed by basic ash
components, the total amount of SO , HCl, and HF in the flue gas is reduced
2
respectively. The flue gas purification consists of an electrostatic precipitator, a two-
stage gas scrubber for the removal of acid gases (using NaOH and CaCO for
3
neutralization), a denitrogenation unit (DeNOx with selective catalytic reduction
using NH ) and an entrained flow absorber with active carbon injection for the
3
removal of dioxins and heavy metals. The plant is a semidry type; all wastewater is
evaporated in a spray dryer after the heat exchanger.
The processes and calculations are distributed to several MS–Excel workbooks.
The processes represented by the workbook files are linked together by their
input–output sheets. The division into workbooks and their major dependencies are
shown in Figure 1.11.
Based on the modular model, a future scenario, scenario 3 to be used in Chapter
7, was created for an MSWI similar to the current plant in Tarragona, but with
DeNOx as an additional gas cleaning system. An overview of the calculated inputs
and outputs for the SIRUSA waste incineration plant is given in Table 1.3. All the

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