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Impressum
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Economic
evaluation of NOx abatement techniques in the European Cement Industry
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Final Report
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September 1998
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Author:
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Jan Wulf-Schnabel
Dr. Joachim Lohse
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| Content |
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1. Background and Scope of this Study
2. NOx emissions from the European Cement Industry
3. Techniques for reduction of NOx emissions
4. Costs of the various NOx control techniques
5. External Costs of unreduced NOx emissions
6. Commercial advantages from using wastes as
fuel substitutes
7. Summary and Recommendation
8. Evaluated Literature
Annex
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| 1. Background and Scope of this Study |
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To an increasing extent, cement kilns are burning waste as a secondary
fuel. Until today, they are not covered by European legislation
that has set standards for pollution to air from plants for municipal
waste incineration, in particular Directives 89/429/EEC and 89/369/EEC.
The Commission is in the process of considering a revision to the
emission limit values set by the 1989 Directives. As part of the
revision it is considering extending the scope of these Directives
to cover cement kilns that burn waste as fuel, and in particular
to set standards for emissions of nitrogen oxides (NOx) from such
plants.
It is the objective of this study to consider the costs and benefits
of extending the scope of the Incineration Directive to specify
emission limit values from cement kilns burning waste as fuel.
Starting from the present situation of actual NOx emission levels
from existing cement kilns, the various technical options for a
reduction of NOx emissions are to be presented and discussed. These
technical alternatives shall be examined for
- the emission reduction that can be achieved by such techniques
and
- the investment and operational costs that these techniques
will eventually cause for the operator of the cement kiln.
At the macro-economic level, the costs of the NOx abatement measures
are to be compared to the damage costs of unreduced NOx emissions
from cement kilns burning waste as fuel. [For this cost-benefit-analysis
at the macro-economic level, the results from methodology developed
by ETSU (1996) for their examination of the costs and benefits of
the proposed new emission limits for municipal waste incineration
plants, will be transferred without detailed discussion.
On an individual plant level, the NOx reduction costs are compared
to the economic advantage that is given for the operator of a cement
kiln when he uses waste as a secondary fuel. |
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| 2. NOx emissions from the European Cement
Industry |
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On an average, the European cement kilns emit circa 1.300 milligrams
of nitrogen oxides per norm cubic meter of stack gas [mg NOx/Nm³,
referring to dry gas, 0 °C, 1 atm and 10% O2]. Emissions
of older plants often lie around 2.000 mg NOx/Nm³, while already
today some modern kilns emit less than 500 mg NOx/Nm³.
These NOx emissions from the European cement industry add up to
a total annual emission of 450.500 Mg NOx. This corresponds to between
10 and 15 per cent of the overall NOx emissions from all industrial
point sources, or 3-4 per cent of all NOx emissions (including diffuse
sources) in Europe.
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| 3. Techniques for reduction of NOx emissions |
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A variety of techniques have been developed in order to reduce
the NOx emission level from cement kilns (see Annex, Table 1). These
include general techniques of process control optimisation and primary
measures like fuel selection, low-NOx burners and staged combustion
that are able to reduce the formation of NOx at the source, but
also secondary measures like selective non-catalytic reduction (SNCR)
and selective catalytic reduction (SCR). With these latter techniques,
NOx emissions are reduced by a chemical reaction with a reducing
agent (mostly ammonia or ammonia water) that is injected into the
exhaust gas stream at a suitable temperature.(1)
By a combination of primary measures, at many European
cement kilns the NOx emission level has successfully been reduced
to circa 800-1100 mg NOx/Nm³, depending on individual circumstances.
Some modern kilns are even able to control their NOx emissions safely
below 500 mg/Nm³ by using only primary measures.
By using the SNCR technique, emission levels of 500-800
mg/Nm³ can be achieved, depending on the original emission level.(2)
Today, SNCR is in large scale operation at a number of European
kilns. It is applicable to those types of cement kilns (normally
preheater kilns) where the required temperature window is accessible.(3)
Still lower NOx emission levels (between 100 and 200 mg/Nm³)
can be achieved by the SCR technique. In the past, this technique
has been widely used for NOx abatement in other industries like
coal-fired power plants and waste incinerators. On cement kilns,
exhaust gas treatment before ("high-dust" SCR) or behind the electrostatic
precipitator ("low-dust" SCR) is principally possible. High dust
systems are preferred for both technical and economic reasons (IPTS,
1998), provided that the catalyst is not destroyed by the high concentrations
of dust.
After several successful pilot plant investigations in Italy, Austria
and Sweden in which no loss of catalyst was observed, a full-scale
SCR demonstration plant is now under construction in Germany.
If NOx emissions are controlled by primary measures only, the achievable
emission levels mentioned above may occasionally be exceeded for
short periods of time. In contrast to this, SNCR and SCR are able
to prevent such short-term peak emissions.
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| 4. Costs of the various NOx control techniques
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In this section, the annual costs of the various NOx control techniques
are calculated as capital expenditure account according to the static
method. The depreciation period was set at 10 years, the calculative
interest rate at 10 per cent annually (which is fairly high in comparison
to an interest rate of 6% p.a. which is common for investments in
environmental protection measures).
In addition to the capital costs, the operating costs were calculated
on the basis of estimated costs for consumables, electricity, pressure
air, maintenance and repair costs, and personnel. Assumptions on
costs are based on information received from kiln operators and
machine and plant engineering firms.
By this method, annual costs were calculated for the technical options
- combination of primary measures (i.e. process control optimisation,
low-NOx burners and fuel selection)
- a) + staged combustion
- SNCR
- SCR.
Primary measures are effective only when a combination of process
control optimisation, improved firing technique, low-NOx burners and
fuel selection is applied. Their costs must not be solely allocated
to NOx reduction because they bring about significant economic benefits
like improved product quality and reduced energy demand of the kiln.
Necessary adaptations of low-NOx burners to the specific kiln routine
may cause more frequent down times at the beginning that will be overcome
after some experience. Operating costs consist of maintenance and
repair costs of process automation and low-NOx burners, costs for
cooling of the main flame, and increased costs for fuel with a low
nitrogen content.
Staged combustion is calculated separately because it is not
feasible for all kiln types but mainly for precalciner kilns. Costs
of staged combustion therefore must be seen in addition to the costs
of primary measures.
The costs of the secondary measures SNCR and SCR are characterised
by higher investment costs for SCR but higher operating costs for
SNCR. Kiln capacity has little influence on the investment costs but
is crucial for the operating costs: these are dominated by the ammonia
(NH3) consumption which itself depends on the NH3
dosage, the exhaust gas volume and thus the kiln capacity. NH3
dosage is relatively lower for the catalytic reduction (SCR) technique
that achieves optimum performance of 90% NOx reduction at a stochiometric
ratio of 0,9 (0,9 Mole of NH3 for reduction of 1 Mole NOx),
while SNCR requires an average molar ratio of 1,2 in order to achieve
its optimum of 60% NOx reduction. For costs of both SNCR and SCR,
key parameters are the initial NOx level in the raw gas and the NOx
target concentration, because for economic reasons many kiln operators
will inject only the minimum amount of NH3 that will suffice
to achieve the target. For calculation of SCR costs, an exchange of
catalyst after five years is taken into account. Costs of 25% ammonia
water are reported by various experts between 65 and 100 ECU per metric
tonne(4) (our calculations are based
on 80 ECU/Mg).
Repair and maintenance costs are assumed at 2% of the capital investments.
For all calculations, energy costs are assumed at 0,04 ECU/kWh (according
to CEMBUREAU, 1997). They make up only a minor contribution to the
overall costs.
The cost accounting results were related to three different
kiln sizes, "kiln A" with a capacity of 1.000 Mg clinker per day [Mg/d],
"kiln B" producing 2.500 Mg/d and "kiln C" with a daily production
of 5.000 Mg clinker. For these typical kiln sizes, the specific costs
of NOx reduction measurements in terms of ECU per metric tonne of
clinker produced [ECU / Mg clinker] are calculated (see Annex to this
study).
The respective costs of the various NOx reduction techniques at the
different kilns are calculated for two different initial emission
levels (2.000 and 1.300 mg/Nm³) and for both optimum reduction and
reduction to a pre-set emission level (Tables 2, 3 and 4). The results
are presented in graphical form in Figures 1-4.
In effect, the costs of the combined primary measures are between
0,68 and 1,6 ECU per Mg of clinker; an additional staged combustion
will cost an extra 0,05 - 0,23 ECU/Mg clinker. (It should be kept
in mind here that costs of process control bring about other economic
benefits with respect to product quality and energy demand).
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As can be seen from Table 4, NOx reduction to 800 mg/Nm³ or lower
by the SNCR technique will cost between 0,47 and 1,4 ECU/Mg clinker,
depending largely on the quantitative ammonia consumption and hence
on the initial NOx emission level and the target level to be achieved.
Concerning the costs of the SCR technique, less practical experience
has been made so far. Starting from an initial level of 1.300 mg NOx
/Nm³, these costs will make up between 0,49 and 1,44 ECU / Mg clinker
as long as the same target levels as for SNCR are to be achieved (e.g.
800 or 500 mg/Nm³).
SCR is the only technique that can safely achieve NOx levels below
200 mg/Nm³. It will then cost circa 0,75-1,87 ECU/Mg clinker. Ultimately,
the operating time of the catalyst will be crucial for the annual
costs of SCR. This life-time of catalyst, however, has not yet been
determined at a full-scale installation.
In Table 5 (Annex), an alternative mathematical model is used to calculate
the annual equivalent costs of the NOx minimisation measures. For
this calculation, the discount rate was set at 8 per cent annually.
When this model is applied to "kiln B" and an initial NOx emission
level of 2.000 mg/Nm³, the annual equivalent costs are between 4,1
and 6,9 per cent higher than the respective costs calculated by the
static method. |
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| 5. External Costs of unreduced NOx emissions |
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The external costs of industrial emissions of nitrogen
oxides have been assessed for waste incinerators by ETSU (1996).
For three municipal locations in Europe, ETSU calculated the damage
to human health, materials and buildings, and secondary effects
of ozone that is formed by atmospheric reactions of NOx as follows:
External costs of NOx (in ECU / Mg of NOx)
for a stack height of 100m [ETSU 1996]
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Location
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Human health |
Materials & Buildings |
Ozone |
Sum |
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Paris
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16.874
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236
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2.530
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19.640
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Stuttgart
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15.576
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307
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2.530
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18.413
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Birmingham
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6.726
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165
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2.530
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9.421
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For all three sites, damage to human health
is the biggest external effect even although only the acute injuries
to human health were taken into account by the authors. Damage to
materials is relatively low in relation to the other external costs.
The external damage from ozone formation is considered to be irrespective
of the location because of long-range atmospheric transport.
Along the lines of the ETSU study, the externalities of NOx emissions
from the European cement industry must be assumed to lie between the
theoretical extremes of circa 2.500 per Mg of NOx for a fictitious
cement kiln in an absolutely remote area where no health and material
damages are caused and damage from ozone is the only external factor,
and an upper value of circa 20.000 ECU / Mg NOx for a cement kiln
in a densely populated area like Paris.
In practice, waste incinerators are often located in more densely
populated areas where most of the municipal waste arises. Cement kilns
are normally located on the site of the geogenic ressources of raw
materials, which can be in rural areas as well as in close vicinity
to a city.
For the assessment of the external cost-benefit ratio of NOx emission
reductions in the cement industry, two scenarios were calculated,
one on the basis of an external damage of 5.000 ECU per Mg NOx, the
second one on the basis of 10.000 ECU damage per Mg NOx. For these
two scenarios, the externalities were calculated for two kilns, "Variant
A" with an initial emission level of 1.300 mg NOx / Nm³
(European average), "Variant B" with an initial NOx emission
of 2.000 mg NOx /Nm³.
As can be seen from Table 6, a reduction of NOx emissions from the
cement industry will significantly reduce the external damage caused
by these emissions. For two typical cases, the costs and benefits
from NOx reduction measures are plotted in graphical form in Figures
5 and 6. The ratio between these benefits and the costs which are
necessary to achieve is calculated in Table 7.
Starting from the European emission average of 1.300 mg NOx /Nm³,
every ECU that is spent for NOx reduction will yield external benefits
worth between 2 and 31 ECU, depending on the detailed conditions of
the single case. Because of the maximum reduction of external damages,
the largest cost-benefit ratio of 1:31 is achieved by an optimum application
of the SCR technique (i.e. target emission level < 200 mg /Nm³)
if the external damage of NOx is assumed to be 10.000 ECU/Mg NOx (Table
7).
For an initial emission level of 2.000 mg NOx per Nm3, the cost-benefit
ratio of NOx reduction measures will lie between 1:4 and 1:42. Again,
the SCR technique is able to yield the highest benefits.
Implementation of a legal NOx emission limit of 800 mg / Nm³
on all European cement kilns will yield cost-benefit ratios between
1:3 and 1:33, depending on the circumstances of the individual case.
These cost-benefit ratios will decrease slightly (between four and
seven per cent) when they are based on the alternative calculating
model of annual equivalent costs instead of annual costs by the static
method. On the other hand, cost-benefit ratios will be higher by 50
per cent when the damage costs are assumed to be 15.000 ECU/Mg NOx
instead of 10.000 ECU/Mg NOx. |
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| 6. Commercial advantages from using wastes
as fuel substitutes |
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By taking in wastes as secondary fuel, an economic advantage is
given for the operator of a cement kiln for two reasons: On the
one hand, he can save expenses for regular fuel, on the other hand
he can charge a disposal fee for the wastes (Figure 7).
Based on data about fuel costs and disposal fees that was obtained
from various industries, the economic net revenue from the substitution
of 5% of regular fuel by wastes as secondary fuel is estimated at
circa 0,7 ECU per Mg of clinker produced.
In practice, many European kiln operators are presently substituting
between 25% and 50% of their energy demand by secondary fuels, corresponding
to an economic advantage of often more than 5 ECU/Mg clinker.
Depending on the kiln size, the proportion of wastes whose co-incineration
can cover the costs of NOx reduction measurements, will lie between
5 and 7% of the overall energy demand for both primary measures
and the SNCR technique. Substitution of 5-10% of the energy demand
can finance the same emission reduction (from 1.300 to 500 mg NOx
/ Nm³) by applying the SCR technique.
Between 6 and 12% of regular fuel have to be substituted by wastes
in order to finance a reduction of NOx emissions from 2.000 to 800
mg / Nm³ by either the SNCR or the SCR technique.
In a medium-size or large kiln equipped with a cyclone preheater,
for achievement of the same emission reduction the costs of SCR
can be equal or even lower than the costs for SNCR (Table 4 and
Figures 3-4).
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| 7. Summary and Recommendation |
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A variety of techniques have been developed that allow cement kilns
to reduce their emissions of nitrogen oxides to levels below 800
mg NOx /Nm³. The most relevant techniques to be mentioned here are
several primary measures, staged combustion, selective non-catalytic
reduction (SNCR), and the rather new technique of selective catalytic
reduction (SCR).
Although not every one of these techniques is applicable to each
kiln type, for every kiln there is at least one technical option
feasible that enables the operator to control the NOx emissions
below the above-mentioned level.
When the allowed NOx emission level for cement kilns is lowered
to 800 mg / Nm³, the external benefit from the avoided damage caused
by NOx emissions will be between three and 33 times higher than
the necessary expenses for the reduction measures.
Depending on the initial emission level before the technical improvement,
for the annual costs of the NOx reduction measures the kiln operator
will have to spend approximately the revenue which he receives from
co-incineration of wastes equivalent to between 5 and 12 per cent
of the kilns total energy demand. In many cases, the expenses for
NOx reduction measures will even be much lower than this.
For most kilns, more than one technical option is available to achieve
the proposed NOx emission reduction below 800 mg/Nm³. Depending
on the individual circumstances, some of these options are able
to achieve even lower emission levels around 500 mg NOx per Nm³.
There are, however, a number of cement kilns that might face difficulties
if the allowed NOx emissions were legally restricted to 500 mg/Nm³,
because the well-established technologies are either not applicable
to the specific kiln type, or they will not suffice to achieve the
required target level of 500 mg/Nm³.
A legal limitation of NOx emissions to a level below 200 mg/Nm³
would force all kiln operators to instal an SCR catalyst. The external
cost-benefit ratio for such a reduction will lie between 1:7 and
1:42 and will thus be significantly higher than for the NOx reduction
to 800 mg/Nm³. However, no long-term experiences with full-scale
SCR installations have been made yet in the cement industry, thus
leaving a certain degree of uncertainty about the life-time of the
catalyst and the subsequent overall costs of this technique.
At present, it may therefore be too early to justify an emission
limit of 200 mg/Nm³ for every cement kiln in Europe. Because of
the optimum cost-benefit ratio, but depending on the future experiences
with the SCR technique, in a medium-term perspective a legal emission
limit of 200 mg/Nm³ maybe appropriate for those European cement
kilns that are co-incinerating wastes on a large scale.
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8. Evaluated Literature |
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BACHER 1998: Betriebsergebnisse mit einer SCR-Pilotanlage - Diskussion
gesamtökologischer Aspekte, Fachseminar des Bayrischen Landesamt
für Umweltschutz, Wackersdorf, 02.07.98.
BILLHARDT et al., 1996: Stand der NOx-Minderung in der Zementindustrie.
- ZKG International 49, 1996, No. 10, pp. 545-560.
BRAND, WANKA 1990: Brennstoffeinsparungen an einem Lepolofen durch
Ionisierung der Primärluft mit dem Vapormid-Verfahren, ZKG International
43, 1990, No.1, pp. 1-12.
BUWAL 1996: Bundesamt für Umwelt, Wald und Landschaft (Hrsg.): NOx-Minderung
in Zementwerken, Stand der Technik, Bern 1996.
CEMBUREAU, 1997: Best available techniques for the Cement Industry.
- Brussels, 11/1997.
ETSU, 1996: Economic Evaluation of the Draft Incineration Directive.
- Report produced for the European Commission DG XI, Contract N°
B4-3040/95/001047/MAR/B1.
HACKEL/MAUSCHITZ 1997: Albert Hackl und Gerd Mauschitz: Emissionen
aus Anlagen der österreichischen Zementindustrie II, Jahresreihe
1994 - 1996, Wien Juli 1997.
IPTS, 1998: Draft Reference Document on best available techniques
in the Cement and Lime industries. - Institute for Prospective Technological
Studies, European IPPC Bureau, Seville, August 1998.
KIRSCH 1996: Schriftliches Statement als Obmann des Ausschusses
„Umwelt" des Vereins Deutscher Zementwerke (VDZ) zur Anhörung über
die Begrenzung der Stickstoffoxid-Emissionen in der Zementindustrie
durch den Länderausschuß für Immissionsschutz (LAI) am 20.05.1996,
Düsseldorf.
KUHLMANN 1996: Wortbeitrag als Vertreter des Vereins der Deutschen
Zementindustrie (VDZ) zur Anhörung über die Begrenzung der Stickstoffoxid-Emissionen
in der Zementindustrie durch den Länderausschuß für Immissionsschutz
(LAI) am 20.05.1996, Düsseldorf.
REITER & STROH 1995: Behandlung von Abfällen in der Zementindustrie,
Bundesministerium für Umwelt (Hrsg.), Band 72, Wien, Dezember 1995.
ROSE 1996: Wortbeitrag als Anlagenbauer zur Anhörung über die Begrenzung
der Stickstoffoxid-Emissionen in der Zementindustrie durch den Länderausschuß
für Immissionsschutz (LAI) am 20.05.1996, Düsseldorf.
ROSEMANN 1996: Schriftliches Statement der Alsen AG zur Anhörung
über die Begrenzung der Stickstoffoxid-Emissionen in der Zementindustrie
durch den Länderausschuß für Immissionsschutz (LAI) am 20.05.1996,
Düsseldorf.
RUHLAND 1996: Schriftliches Statement zur Anhörung über die Begrenzung
der Stickstoffoxid-Emissionen in der Zementindustrie durch den Länderausschuß
für Immissionsschutz (LAI) am 20.05.1996, Düsseldorf.
SAMANT 1998: Betriebsergebnisse mit einer SCR-Pilotanlage - Konzeptionierung
einer Großanlage. - Fachseminar des Bayrischen Landesamt für Umweltschutz,
Wackersdorf, 02.07.98.
SCHNEIDER 1996: Sekundäre Minderungsverfahren, sonstige Minderungsverfahren
und Stand der Technik außerhalb der Bundesrepublik Deutschland.
Schriftliche Stellungnahme zur Anhörung über die Begrenzung der
Stickstoffoxid-Emissionen in der Zementindustrie durch den Länderausschuß
für Immissionsschutz (LAI) am 20.05.1996, Düsseldorf.
UBA Österreich 1997: Diskussionsentwurf der Studie „Beste verfügbare
Technik bei Anlagen zur Zementherstellung". B. Reiter, I. Schindler,
J. Stubenvoll, Wien 7/97.
UBA 1995: Demonstrationsanlage zur prozeßtechnischen Minderung von
NOx-Emissionen durch Reduktion mit CO und anschließender Nachverbrennung.
- Dr. Billhardt im Auftrag des Umweltbundesamtes, 3071-5/207, Berlin,
12/1995.
XELLER 1998: Neue Entwicklungen bei der NOX-Minderung in der Zementindustrie,
Teil 1, ZKG-International, Nr. 3/1998; Teil 2, ZKG-International,
Nr. 4/1998.
Further consultations for this project were held with:
Austrian Energy and Environment, Elektro Mark AG, Elex AG, KHD
Humboldt-Wedag, Kirchdorfer Zementwerk Hofmann GesmbH, Krupp-Polysius
AG, Lurgi Umwelt GmbH, Noell-KRC Energie- und Umwelttechnik GmbH,
Readymix Zementwerke GmbH, Spenner Zement GmbH& Co. KG, Umweltbundesamt
Berlin, Umweltbundesamt Wien.
The contribution of competent persons from these companies and institutions
to this study is gratefully acknowledged.
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| Annex |
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Tables
Table 1Technical options for NOx reduction
Table 2 Cost comparison of various NOX reduction measures at optimum
reduction efficiency and an initial emission level of 2.000 mg/Nm3
Table 3 Cost comparison of various NOX reduction measures
at optimum reduction efficiency and an initial emission
level of 1.300 mg/Nm3
Table 4 Costs of NOx reduction measures for various target
emission levels
Table 5 Alternative calculation model of annual equivalent costs
for "kiln B"
Table 6 Annual equivalent costs at optimum reduction efficiency
Table 7 External damage from NOx emissions and benefit from NOx
reduction measures
Table 8 Ratio between benefits and costs.
Figures
Figure 1 Optimum NOx reduction and costs for various techniques
(initial emission level 2.000 mg NOx/Nm³)
Figure 2 Optimum NOx reduction and costs for various techniques
(initial emission level 1.300 mg NOx/Nm³)
Figure 3 Costs of NOx reduction from 2.000 to 800 mg NOx/Nm³
Figure 4 Costs of NOx reduction from 1.300 to 500 mg NOx/Nm³
Figure 5 Costs and benefits of NOx reduction measures
(initial level 1.300 mg NOx/Nm³, damage 5.000 ECU/Mg NOx)
Figure 6 Costs and benefits of NOx reduction measures
(initial level 2.000 mg NOx/Nm³, damage 10.000 ECU/Mg NOx)
Figure 7 Net revenue from co-incineration of wastes.
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Table 1 Technical options for NOx reduction |
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| Technical measure |
NOX reduction achieved in practice |
Comments |
| Primary measures |
Optimum emission level:
< 500 mg/Nm3
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only by combination of several measures (at new kilns) |
| Process control optimisation |
0 to 20% reduction potential |
automatic process control is state of the art today at numerous
cement kilns in the EU. |
| LowNOx - burner |
0% to 30% reduction potential |
exchange of conventional burners is state of the art at numerous
cement kilns in the EU. |
| Ionisation |
0% |
supplier claims a reduction potential up to 25% of total NOx. |
| Fuel selection |
circa 50% in combination with other measures; circa 25% NOx
reduction potential by fuel selection alone |
e.g. switch from pit-coal to lignite or secondary fuels with
high proportion of volatile constituents |
| shift of energy input from main burner to secondary firing |
10 to 30% reduction |
not applicable to all kiln types |
| staged combustion |
10 to 40% reduction |
not applicable to all kiln types; success depends on initial
NOx level |
| fluidized bed combustion |
50% reduction (only in combination with other primary measures) |
expensive for small and medium-size kilns; only feasible for
new kilns (not for all kiln types) |
| Secondary measures |
Optimum 100 - 200 mg/m3 (with SCR technique) |
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| SNCR |
reduction potential 60% |
risk of NH3 escape |
| SCR |
reduction potential 90% |
NOx emission can be safely kept below 200 mg/m3 |
| Lurenox |
reduction potential 60-70% |
technique in R&D state only; special catalyst required. |
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Table 2 Cost comparison of various NOx
reduction measures at optimumreduction efficiency and an initial
emission level of 2.000g/Nm3 [in ECU] |
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| Kiln A |
Prim.M
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(PM+)SC
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SNCR
|
SCR
|
| Repayment |
210.000
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50.000
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85.000
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210.000
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| Interest |
105.000
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25.000
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42.500
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105.00
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| Operation costs |
270.00
|
10.000
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383.140
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366.605
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| Annual costs |
585.000
|
85.000
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510.640
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681.605
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| Kiln B |
Prim.M
|
(PM+)SC
|
SNCR
|
SCR
|
| Repayment |
22.000
|
55.000
|
90.000
|
230.000
|
| Interest |
110.000
|
27.500
|
45.000
|
115.000
|
| Operation costs |
505.000
|
10.000
|
933.350
|
795.012
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| Annual costs |
835.000
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92.500
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1.068.350
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1.140.012
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| Kiln C |
Prim.M
|
(PM+)SC
|
SNCR
|
SCR
|
| Repayment |
230.000
|
60.000
|
100.000
|
260.000
|
| Interest |
115.000
|
30.000
|
50.000
|
130.000
|
| Operation costs |
890.000
|
10.000
|
1.850.699
|
1.890.025
|
| Annual costs |
1.235.000
|
100.000
|
2.000.699
|
1.890.025
|
| |
| |
| NOx reduction costs in ECU/Mg clinker |
| |
Prim.M
|
(PM+)SC
|
SNCR
|
SCR
|
| Kiln A |
1,60
|
0,23
|
1,40
|
1,87
|
| Kiln B |
0,92
|
0,10
|
1,17
|
1,25
|
| Kiln C |
0,68
|
0,05
|
1,10
|
1,04
|
| |
| |
| Achievable emission level [mg NOx / Nm3] |
| |
Prim.M
|
(PM+)SC
|
SNCR
|
SCR
|
| Kiln A - C |
1.100
|
900
|
800
|
200
|
|
| |
Explanatory remark: Staged combustion (SC) is technically
feasible only in combination with Primary Measures (PM). Costs for
SC therefore have to be taken in addition to costs for PM while
the achievable emission level is to be seen in combination of PM+SC.
|
| |
|
| |
|
| |
|
| |
Table 3 Cost comparison of various NOx
reduction measures at optimumreduction efficiency and
an initial emission level of 1.300 mg/Nm3[in ECU] |
| |
| Kiln A |
Prim.M
|
(PM+)SC
|
SNCR
|
SCR
|
| Repayment |
210.000
|
50.000
|
85.000
|
210.000
|
| Interest |
105.000
|
25.000
|
42.500
|
105.000
|
| Operation costs |
270.000
|
10.000
|
254.991
|
270.493
|
| Annual costs |
585.000
|
85.000
|
382.491
|
585.493
|
|
|
| Kiln B |
Prim.M
|
(PM+)SC
|
SNCR
|
SCR
|
| Repayment |
220.000
|
55.000
|
90.000
|
230.000
|
| Interest |
110.000
|
27.500
|
45.000
|
115.000
|
| Operation costs |
505.000
|
10.000
|
612.977
|
554.733
|
| Annual costs |
835.000
|
92.500
|
747.977
|
899.733
|
|
|
| Kiln C |
Prim.M
|
(PM+)SC
|
SNCR
|
SCR
|
| Repayment |
230.000
|
60.000
|
100.000
|
260.000
|
| Interest |
115.000
|
30.000
|
50.000
|
130.000
|
| Operation costs |
890.000
|
10.000
|
1.209.955
|
1.019.466
|
| Annual costs |
1.235.000
|
100.000
|
1.350.000
|
1.409.466
|
|
|
| |
| NOx reduction costs in ECU/Mg clinker |
| |
Prim.M
|
(PM+)SC
|
SNCR
|
SCR
|
| Kiln A |
1,60
|
0,23
|
1,05
|
1,60
|
| Kiln B |
0,92
|
0,10
|
0,82
|
0,99
|
| Kiln C |
0,68
|
0,05
|
0,75
|
0,77
|
|
|
| |
| Achievable emission level [mg NOx / Nm3] |
| |
Prim.M
|
(PM+)SC
|
SNCR
|
SCR
|
| Kiln A - C |
1.100
|
800
|
500
|
130
|
| |
|
| |
Explanatory remark: Staged combustion
(SC) is technically feasible only in combination with Primary Measures
(PM). Costs for SC therefore have to be taken in addition to costs
for PM while the achievable emission level is to be seen in combination
of PM+SC. |
| |
|
| |
|
| |
|
| |
Table 4 Costs of NOx reduction measures
for various target emission levels
(in ECU/Mg clinker) |
| |
|
Variant A: initial emission level 1300 mg NOx/Nm3
(EU average)
|
| |
|
target emissons level
|
1300
|
1000
|
800
|
500
|
200
|
| Kiln A (1000t clinker/d) |
|
| Primary+MSC |
0
|
1,84
|
1,84
|
1,84
|
n.p.
|
| SNCR |
0
|
0,61
|
0,78
|
1,05
|
n.p.
|
| SCR |
0
|
1,24
|
1,32
|
1,44
|
1,58
|
| |
| Kiln B (2500t clinker/d) |
|
| Primary+MSC |
0
|
1,02
|
1,02
|
1,02
|
n.p.
|
| SNCR |
0
|
0,39
|
0,55
|
0,82
|
n.m.
|
| SCR |
0
|
0,62
|
0,70
|
0,82
|
0,75
|
| |
| Kiln C (5000 t clinker/d) |
|
| Primary+MSC |
0
|
0,73
|
0,73
|
0,73
|
n.p.
|
| SNCR |
0
|
0,31
|
0,47
|
0,75
|
n.m.
|
| SCR |
0
|
0,41
|
0,49
|
0,61
|
0,75
|
|
|
Variant B: initial emission level 2000 mg NOx/Nm3
(EU upper level)
|
| |
|
target emissons level
|
1300
|
1000
|
800
|
500
|
200
|
| Kiln A (1000t clinker/d) |
|
| Primary+MSC |
0
|
1,84
|
1,84
|
1,84
|
n.p.
|
| SNCR |
0
|
0,61
|
0,78
|
1,05
|
n.p.
|
| SCR |
0
|
1,24
|
1,32
|
1,44
|
1,58
|
| |
| Kiln B (2500t clinker/d) |
|
| Primary+MSC |
0
|
1,02
|
1,02
|
1,02
|
n.p.
|
| SNCR |
0
|
0,39
|
0,55
|
0,82
|
n.m.
|
| SCR |
0
|
0,62
|
0,70
|
0,82
|
0,75
|
| |
| Kiln C (5000 t clinker/d) |
|
| Primary+MSC |
0
|
0,73
|
0,73
|
0,73
|
n.p.
|
| SNCR |
0
|
0,31
|
0,47
|
0,75
|
n.m.
|
| SCR |
0
|
0,41
|
0,49
|
0,61
|
0,75
|
| |
|
| |
|
| |
|
| |
|
| |
Table 6: Annual equivalent costs at optiminm
reduction efficiency
(Kiln B, initial level 2.000 NOx/Nm3) |
| |
Primary Measures
(Target level 1.100 mg NOx/Nm3) |
|
Year
|
Expenditure
|
Operating
costs
|
Sum
|
Discount
factor
|
Present value
|
Net present value
|
Annual equivalent
costs
|
|
0
|
2.200.000
|
505.000
|
2.705.000 |
1.00
|
2.705.000
|
5.859.678
|
873.265
|
|
1
|
0
|
505.000
|
505.000
|
0,93
|
467.593
|
|
|
|
2
|
0
|
505.000
|
505.000
|
0,86
|
432.956
|
|
|
|
3
|
0
|
505.000
|
505.000
|
0,79
|
400.885
|
|
|
|
4
|
0
|
505.000
|
505.000
|
0,74
|
371.190
|
|
|
|
5
|
0
|
505.000
|
505.000
|
0,68
|
343.695
|
|
|
|
6
|
0
|
505.000
|
505.000
|
0,63
|
318.236
|
|
|
|
7
|
0
|
505.000
|
505.000
|
0,58
|
294.663
|
|
|
|
8
|
0
|
505.000
|
505.000
|
0,54
|
272.836
|
|
|
|
9
|
0
|
505.000
|
505.000
|
0,50
|
252.626
|
|
|
| |
Primary Measures and Staged Combustion
(Target level 900 mg NOx/Nm3) |
|
Year
|
Expenditure
|
Operating costs
|
Sum
|
Discount
factor
|
Present value
|
Net present value
|
Annual equivalent costs
|
|
0
|
2.750.000 |
515.000
|
3.265.000
|
1.00
|
3.265.000
|
7.663.883 |
1.142.145 |
|
1
|
0
|
515.000
|
515.000
|
0,93
|
476.852
|
|
|
|
2
|
0
|
515.000
|
515.000
|
0,86
|
441.529
|
|
|
|
3
|
0
|
515.000
|
515.000
|
0,79
|
408.824
|
|
|
|
4
|
0
|
515.000
|
515.000
|
0,74
|
378.540
|
|
|
|
5
|
0
|
515.000
|
515.000
|
0,68
|
350.500
|
|
|
|
6
|
0
|
515.000
|
515.000
|
0,63
|
324.537
|
|
|
|
7
|
0
|
515.000
|
515.000
|
0,58
|
300.498
|
|
|
|
8
|
0
|
515.000
|
515.000
|
0,54
|
278.238
|
|
|
|
9
|
0
|
515.000
|
515.000
|
0,50
|
257.628
|
|
|
| |
SNCR
(Target level 800 mg NOx/Nm3) |
|
Year
|
Expenditure
|
Operating costs
|
Sum
|
Discount
factor
|
Present value
|
Net present value
|
Annual equivalent costs
|
|
0
|
900.000
|
933.350
|
1.833.350
|
1.00
|
1.833.350
|
7.663.883
|
1.142.145
|
|
1
|
0
|
933.350
|
933.350
|
0,93
|
864.213
|
|
|
|
2
|
0
|
933.350
|
933.350
|
0,86
|
800.197
|
|
|
|
3
|
0
|
933.350
|
933.350
|
0,79
|
740.923
|
|
|
|
4
|
0
|
933.350
|
933.350
|
0,74
|
686.040
|
|
|
|
5
|
0
|
933.350
|
933.350
|
0,68
|
635.222
|
|
|
|
6
|
0
|
933.350
|
933.350
|
0,63
|
588.169
|
|
|
|
7
|
0
|
933.350
|
933.350
|
0,58
|
544.601
|
|
|
|
8
|
0
|
933.350
|
933.350
|
0,54
|
504.260
|
|
|
|
9
|
0
|
933.350
|
933.350
|
0,50
|
466.907
|
|
|
| |
SCR
(Target level 200 mg NOx/Nm3) |
|
Year
|
Expenditure
|
Operating costs
|
Sum
|
Discount
factor
|
Present value
|
Net present value
|
Annual equivalent costs
|
|
0
|
2.550.000
|
732.512
|
3.282.512
|
1.00
|
3.282.512
|
8.028.578
|
1.196.495
|
|
1
|
0
|
732.512
|
732.512
|
0,93
|
678.252
|
|
|
|
2
|
0
|
732.512
|
732.512
|
0,86
|
628.011
|
|
|
|
3
|
0
|
732.512
|
732.512
|
0,79
|
581.492
|
|
|
|
4
|
0
|
732.512
|
732.512
|
0,74
|
538.418
|
|
|
|
5
|
250.000
|
732.512
|
982.512
|
0,68
|
668.681
|
|
|
|
6
|
0
|
732.512
|
732.512
|
0,63
|
461.607
|
|
|
|
7
|
0
|
732.512
|
732.512
|
0,58
|
427.414
|
|
|
|
8
|
0
|
732.512
|
732.512
|
0,54
|
395.753
|
|
|
|
9
|
0
|
732.512
|
732.512
|
0,50
|
366.438
|
|
|
|
| |
|
| |
|
| |
|
| |
Table 7: External damage from NOx emissions
and benefit from NOx reduction measures |
| |
|
NOx [mg/Nm3]
|
2.000
|
1.300
|
1.000
|
800
|
500
|
200
|
| NOx [kg/Mg clinker] |
4,27
|
2,77
|
2,13
|
1,71
|
1,07
|
0,43
|
|
Reduction
[kg/Mg]
|
| Variante A |
0,00
|
0,00
|
0,64
|
1,07
|
1,71
|
2,35
|
| Variante B |
0,00
|
1,49
|
2,13
|
2,56
|
3,2
|
3,84
|
External costs
[ECU/mg NOx] |
| Scenario 1 |
5.000
|
5.000
|
5.000
|
5.000
|
5.000
|
5.000
|
| Scenario 2 |
10,000
|
10,000
|
10,000
|
10,000
|
10,000
|
10,000
|
External benefit
(Kiln 1 [ECU/Mg clinker]) |
| Scenario 1 |
0,00
|
0,00
|
3,20
|
5,33
|
8,53
|
11,73
|
| Scenario 2 |
0,00
|
0,00
|
6,40
|
10,67
|
17,07
|
23,47
|
External benefit
(Kiln 2 [ECU/Mg clinker]) |
| Scenario 1 |
0,00
|
7,47
|
10,67
|
12,80
|
16,00
|
19,20
|
| Scenario 2 |
0,00
|
14,93
|
21,33
|
25,60
|
32,00
|
38,40
|
External damage
[ECU/Mg clinker] |
| Scenario 1 |
21,33
|
13,87
|
10,67
|
8,53
|
5,33
|
2,13
|
| Scenario 2 |
42,67
|
27,73
|
21,33
|
17,07
|
10,67
|
4,27
|
|
| |
Variant A: 1.300 mg/Nm3 initial level (EU
average)(equivalent to 2,77 kg NOx/mg clinker) |
| |
Variant B: 2.000 mg/Nm3 initial level (equivalent
to 4,27 kg NOx/mg clinker) |
| |
|
| |
|
| |
|
| |
Table 8:Ratio between benefits and costs |
| |
| NOx target level [mg/Nm3] |
1300
|
1000
|
800
|
500
|
200
|
| |
| Variant A: |
External damage 5.000 ECU/Mg NOx |
KilnA
1000 t clinker/d |
Primary +MSC |
|
1,7
|
2,9
|
4,6
|
n.p.
|
| SNCR |
|
5,9
|
6,9
|
8,1
|
n.p.
|
| SCR |
|
2,6
|
4,0
|
5,9
|
7,7
|
Kiln B
2500 t clinker/d |
Primary +MSC |
|
3,1
|
5,2
|
8,4
|
n.p.
|
| SNCR |
|
8,3
|
9,7
|
10,4
|
n.p.
|
| SCR |
|
5,1
|
7,6
|
10,4
|
12,2
|
Kiln C
5000 t clinker/d |
Primary +MSC |
|
4,4
|
7,3
|
11,7
|
n.p.
|
| SNCR |
|
10,3
|
11,3
|
11,5
|
n.p.
|
| SCR |
|
7,8
|
10,9
|
14,0
|
15,7
|
| |
| Variant A: |
External damage 10.000 ECU/Mg NOx |
KilnA
1000 t clinker/d |
Primary +MSC |
|
3,5
|
5,8
|
9,3
|
n.p.
|
| SNCR |
|
10,4
|
13,7
|
16,3
|
n.p.
|
| SCR |
|
5,2
|
8,1
|
11,8
|
14,9
|
Kiln B
2500 t clinker/d |
Primary +MSC |
|
6,3
|
10,5
|
16,8
|
n.p.
|
| SNCR |
|
16,6
|
19,5
|
20,8
|
n.p.
|
| SCR |
|
10,3
|
15,2
|
20,7
|
24,5
|
Kiln C
5000 t clinker/d |
Primary +MSC |
|
8,7
|
14,6
|
23,3
|
n.p.
|
| SNCR |
|
20,6
|
22,5
|
22,9
|
n.p.
|
| SCR |
|
15,7
|
21,8
|
28,0
|
31,5
|
| |
| Variant B: |
External damage 5.000 ECU/Mg NOx |
KilnA
1000 t clinker/d |
Primary +MSC |
4,1
|
5,8
|
7,0
|
n.p.
|
n.p.
|
| SNCR |
7,6
|
13,1
|
9,1
|
n.p.
|
n.p.
|
| SCR |
5,3
|
8,1
|
7,9
|
9,2
|
10,3
|
Kiln B
2500 t clinker/d |
Primary +MSC |
7,3
|
10,5
|
12,6
|
n.p.
|
n.p.
|
| SNCR |
9,9
|
18,2
|
10,9
|
n.p.
|
n.p.
|
| SCR |
9,5
|
15,1
|
12,8
|
14,2
|
15,4
|
Kiln C
5000 t clinker/d |
Primary +MSC |
10,2
|
14,6
|
17,5
|
n.p.
|
n.p.
|
| SNCR |
11,0
|
20,9
|
11,7
|
n.p.
|
n.p.
|
| SCR |
12,7
|
21,7
|
16,3
|
17,6
|
21,1
|
| |
| Variant B: |
External damage 10.000 ECU/Mg NOx |
KilnA
1000 t clinker/d |
Primary +MSC |
8,1
|
11,6
|
13,9
|
n.p.
|
n.p.
|
| SNCR |
15,2
|
26,2
|
18,3
|
n.p.
|
n.p.
|
| SCR |
10,6
|
16,1
|
15,8
|
18,4
|
20,6
|
Kiln B
2500 t clinker/d |
Primary +MSC |
14,7
|
21,0
|
25,2
|
n.p.
|
n.p.
|
| SNCR |
19,8
|
36,4
|
21,9
|
n.p.
|
n.p.
|
| SCR |
18,9
|
30,2
|
25,6
|
28,5
|
30,7
|
Kiln C
5000 t clinker/d |
Primary +MSC |
20,4
|
29,2
|
35,0
|
n.p.
|
n.p.
|
| SNCR |
22,0
|
41,7
|
23,4
|
n.p.
|
n.p.
|
| SCR |
25,4
|
43,3
|
32,6
|
35,2
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42,2
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Variant A: initial emission level 1.300
mg NOx/Nm3 (EU average) |
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Variant B: initial emission level 2.000
mg NOx/Nm3 (EU upper level) |
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n.p.: not possible |
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Figure 1 Optimum NOx reduction and costs
for various techniques
(initial emission level 2.000 mg NOx/Nm³) |
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Figure 2 Optimum NOx reduction and costs
for various techniques
(initial emission level 1.300 mg NOx/Nm³) |
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Figure 3 Costs of NOx reduction from 2.000
to 800 mg NOx/Nm³ |
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Figure 4 Costs of NOx reduction from 1.300
to 500 mg NOx/Nm³ |
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Figure 5 Costs and benefits of NOx reduction
measures
(initial level 1.300 mg NOx/Nm³, damage 5.000 ECU/Mg NOx) |
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Figure 6 Costs and benefits of NOx reduction
measures
(initial level 2.000 mg NOx/Nm³, damage 10.000 ECU/Mg NOx) |
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Figure 7 Net revenue from co-incineration
of wastes |
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1. For a more detailed
technical description, the reader is referred to the "Draft Reference
Document on BAT in the Cement and Lime industries" by IPTS, August
1998. (back)
2. As a general rule, it is said that SNCR can
lower the NOx emissions of a kiln by 60 per cent, corresponding
e.g. to a reduction from 2.000 to 800 mg/Nm³ or from 1.300 to 500
mg/Nm³. Applying SNCR for further NOx reduction below 500 mg/Nm³
appears to be a merely theoretical option that often leads to problems
in practice. (back)
3. On precalciner kilns, it is more difficult
to find a convenient temperature window. These kilns, however, have
much better circumstances for successful primary measures. (back)
4. Some kiln operators can keep these costs
low by using e.g. photographic fluid wastes as the reducing agent;
however, these are not available throughout Europe. (back)
5. Both scenarios will presumably underestimate
the external benefit that will arise from the reduction of NOx emissions
from the cement industry. However, a more detailed analysis would
have to be based on a detailed assessment of one or several specific
sites, which would have been clearly beyond the scope of this study.(back)
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| Contact |
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Dirk
Jepsen |
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