SWISS CEMENT PLANTS AND ALTERNATIVE FUELS: A SUCCESS
STORY
SPEAKER ANDRÉ G. CALUORI
HCB energy management Bündner Cement AG, CH-7204 Untervaz,
Switzerland
The Swiss cement plants have formulated their goal: substitution of up to 75%
of coal and heavy oil by alternative fuels. This program leads to a remarkable
improvement of the environmental situation in Switzerland as well as abroad. In
the mean time these activities contribute to solving the problem with disposing
waste. Moreover, a considerable reduction of waste disposal cost is reached.
Finally energy costs of the cement kilns are reduced.
In 1997, 150´000 tons of alternative fuels were burned in the Swiss cement
kilns: with that the degree of substitution has reached 34%, being nearly half the
objective.
The Swiss cement industry has set its goal: a substitution of up to 75% of fossil
combustibles such as coal and heavy oil by alternative fuels. The alternative
fuels mainly consist in well defined fractions of waste.
In close co-operation with the Swiss federal office for the environment, forest
and landscape such fractions were identified and described in the “thesis
paper”, a document worked out by a body of experts. This document describes
the conditions under which waste fractions can be burnt in cement kilns,
causing an ecological benefit. Permitted waste fractions are listed up in a
“positive list”. Since mid 1998 the combustion of alternative fuels is supported
by the coming to force of the “guidelines for the use of waste in cement kilns”, a
decree of the federal office for the environment, forest and landscape. Thus the
cement industry is enabled to increase the amount of incinerated waste.
Moreover the decree facilitates the decision-making when permissions to
operate kilns with alternative fuels are applied for. In 1997 another two
companies got the permission to burn all waste fractions that meet the
requirements of the thesis paperin their kilns.
This situation has lead to a further increase of the burning of alternative fuels. In
1997 more than 150´000 tons of alternative fuels have been burnt. The degree
of substitution has reached as much as 34% by the end of 1997. This amount of
alternative fuels corresponds to an energetic value of 3´500 TJ being an
equivalent of 140´000 tons of coal.
%
Degree of substitution
100
90
80
70
60
50
40
30
20
10
0
YEAR
1990
91
92
93 94
95
96 97
98
99 2000
Thus the activities of the cement industry are an important contribution to the
Swiss action programme energy 2000 (reduction of energy consumption: 15%
target contribution, reduction of CO2 emissions 13% target contribution).
The contribution of the cement industry is shown in the following pie chart.
Share of cement industry
Sector industry
Other sectors
The pie chart has to be read as follows: the whole circle corresponds to the
overall savings by the programme energy 2000. The cement industry, with its
dominating share in the sector industry, contributes about 15% to the overall
result.
In the cement kilns the following alternative fuels are used: timber, waste oil,
solvents, waste plastics from industry ( without PVC), tyres and rubber, meat
flour, tallow, and dried sewage sludge.
The distribution of these fractions in 1997 was as follows:
Renewable energies
Distribution of
Alternative fuels
1
2
3
4
5
6
7
8
9
10
Semi-renewable
energies
1 waste oil
2. waste petcoke
3. tallow
4. dried sewage sludge
5. timber
6. meat flour
7. various
8. plastics
9. imprg. Saw dust
10. solvents
The share of renewable energies has reached 56´000 tons/a,i.e. one third of the
alternative energy brought into the kilns comes from renewable energies.
The activities are more and more shifted towards the use of renewable
energies, above all dried sewage sludge. The use of dried sewage sludge in
cement kilns is regarded to be an excellent option for it does not only replace
fossil energy but also raw material from the quarry. The ash of sewage sludge
has a favourable composition: It contains SiO2, CaO, AL2O3, and Fe2O3, the
components used in the process of burning clinker. This fact is shown in the
following diagram:
0
100
CaO IN%
20
80
40
60
coal
60
Sewage
Sludge
lignite
3
40
tyr
es
clinker
80
SiO2in%
20
100
0
0
20
40
60
80
100
AL2O3 +Fe2O3 in%
Therefore, in 1998 a study was carried out on this topic. The study examined
the overall environmental impact of several ways of drying and disposing
sludge: drying with fossil fuels or/and waste heat, burning the sludge in
incineration planst, toxic waste incineration plants or cement kilns. With the
parameters total investment, operating costs, primary energy consumption,
emissions of CO2 and NOX1 a ranking of the different options was drawn up with
the goal to evaluate the economic and ecological best way to dry and to dispose
sewage sludge. The result was, that dryng sewage sludge with waste heat or
with about 50% of waste heat and fossil fuels respectively and burning it in
cement kilns is the economic and ecological best way to dispose sewage
sludge: it causes least overall impacts to the environment. At the same time this
option is financially most interesting for all parties, the communities as”holders”
of the sewage sludge, the cement plants and the national economy. The result
of the study is shown in the following graphic:
investment
10
8
NOx –emissions
CO2 emissions
operating costs
primary energy
consumption
average of sevenoptions
drying and burning in cement plants
This way to dispose sewage sludge, which is in fact a conversion into energy
and clinker, opens the way to a potential of 85´000 t/a to be burnt in the Swiss
cement plants.
The Swiss cement plants have started up their website under
www\cemsuisse.ch. It represents a market place to inform holders of waste on
the conditions of cement plants and helps the cement plants to procure
alternative fuels.