7 research outputs found
Stabilization of persistent organic pollutants (POP) in flue gases in a biological waste incinerating facility
ArticleThe article focuses on a technology of flue gases stabilization in biological and hospital
waste incinerating facility. Hazardous particles and compounds formed in flue gas during the
process of thermal waste degradation need to be stabilized according to
an enacted legislation.
The aim of the research is to examine technological process of
polychlorinated dibenzodioxins
and
polychlorinated dibenzofurans
(PCDD/F) elimination in flue gas. PCDD/F
is group of
persistent organic pollutants which are resistant to environmental degradation and
are highly toxic
for the environment in very small amounts.
Experiments were performed in semi operation
hospital waste incinerating plant with heating power 1.5
MW and capacity 250
kg
h
-
1
of
incinerating material. It was observed that
formation of PCDD/F
exponentially grows with
increasing concentration of chlorides in the flue gas, but formation varies based on type of
congener. The highest concentration was measured for HxDF, 17,522
pg
Nm
-
3
and
HpDF,
16,334
pg
Nm
-
3
at chloride
concentration of
867
mg
Nm
-
3
. However, concentration of PCDD
congeners didn ́t exceeded
4,000
pg
Nm
-
3
for the same level of chlorides in flue gas. Two types
of activated carbon
Chezacarb and NORIT were tested for capability to stabilize PCDD/F in flue
gas. Results show that refining
effect for both sorbent are very similar. It was observed that 0.1
g
of activated carbon should be applied per 1
Nm
3
of flue gas in regard to reduce 3
–
4
ng
Nm
-
3
PCDD/F under required emission limit
Energy valorisation of citrus peel waste by torrefaction treatment
ArticleThe article deals with th
e issue of processing and utilization of citrus peel, which often
ends unused with other biodegradable waste. The research is concerned with the energy potential
of this raw material and its torrefaction conversion. The tested materials were orange peel (
C
itrus
sinensis
Osbeck cv 'Valencia',
Citrus sinensis
Osbeck cv 'Murcia') and grapefruit peel (
Citrus
paradise
'Ruby red'). Samples of dried materials underwent torrefaction treatment at 225
°C
,
250
°C
and 275
°C
for 30 minutes. Samples before and after tor
refaction were analysed for
proximate and elemental composition and for calorific value. Consequently, stoichiometric
combustion analyses were done. The torrefaction was performed in a LECO TGA 701
thermogravimetric analyzer under nitrogen atmosphere. The
results of proximate and elemental
analysis showed positive influence of torrefaction on the samples. The highest net calorific value
for orange peel is 24.97
MJ
kg
-
1
at the temperature of 275
°C
. The greatest differences in net
calorific values are betwee
n 225
°C
and 250
°C
where the increase is almost 3
MJ
kg
-
1
.
Subsequently, the increase between the 250
°C
and 275
°C
torrefaction temperatures is 1
MJ
kg
-
1
.
Weight loss at respective torrefaction temperatures showed similar time
-
dependent curves for all
sa
mples. Stoichiometric combustion analysis shows slight differences between original samples,
but great differences after torrefaction processing. Stoichiometric combustion parameters also
change proportionately with increasing temperature of torrefication.
The resulting comnbustion
balance figures show significantly lower need for mass of fuel in the case of the torrefied material
for a given heat output thanks to the net calorific value
being nearly doubled
Specialty types of waste paper as an energetic commodity
ArticleThe collection and recycling rate of paper and paper packaging material has been on a
rise. From 2010 to 2016 in Czech Republic, the recycled amount of all paper went up by 32%,
while the share of energy use in waste paper utilization decreased f
rom 5.5% to 3.8%. However,
not every paper and cardboard product can be recycled, and some are rejected from the recycling
stream. Recycling specialty types of paper with other grades of recyclable paper is often not
possible and their production is not hi
gh enough for their separate recycling to be feasible. If
material utilization is not feasible then within the waste hierarchy the next best treatment is their
energy utilization. Therefore, this article evaluates selected types of specialty paper for thei
r
energy content. They were silicone coated papers, polymer coated papers, and paper cores. For
all samples proximate, elemental and calorimetric analyses were determined and based on them
stoichiometric combustion calculations were performed. Silicon coat
ed papers fared generally
well having small to reasonable ash content 1
–
10% and net calorific value from 15.10 to 17.10
MJ
kg
-
1
on dry basis. Polymer coated papers had ash content around 6% and net calorific value
from value from 16.29 to 22.98
MJ
kg
-
1
on
dry basis. With the exception of paper cores and self
-
copying paper, all evaluated paper types could be recommended as a component in refuse derived
fuels. The least suitable samples were paper cores with nearly 20% wt. of ash and net calorific
value 12.45
MJ
kg
-
1
on dry basis
Hydrothermal carbonization and torrefaction of cabbage waste
ArticleIn recent years, waste biomass has been increasingly becoming an energy source. The
utilization of biomass includes a number of potential treatments: thermochemical,
physicochemical and biochemical. In the food industry, significant amounts of biodegradable
wastes are produced which have to be quickly treated to not pose an environmental problem. In
this work cabbage waste (Brassica oleracea var. capitata) was treated by hydrothermal
carbonization and torrefaction.
Hydrothermal carbonization experiments were carried out in a pressure reactor vessel
Berghof BR-300 (inner volume 400 mL, temperature regulation by Berghof BTC 3000). The
carbonization took place at target temperatures 180 °C and 225 °C. Torrefaction tests were
carried out in a thermogravimetric programmable oven LECO TGA701 under nitrogen
atmosphere at temperatures 225 °C, 250 °C and 275 °C. The residence time was 30 min for both
processes. Proximate and elemental composition, as well as calorific value was analysed in all
samples. To express the influence of the treatments on combustion behaviour, stoichiometric
combustion calculations were performed.
The analyses show a positive effect of both torrefaction and hydrothermal carbonization on fuel
properties in the samples. Most obvious is the reduction in oxygen content which depends on the
process temperature. After hydrothermal carbonization at 225 °C the oxygen content was lowered
by 46.7%. The net calorific value increased proportionally with temperature in both processes.
After hydrothermal carbonization at 225 °C the net calorific value increased on average by
3 MJ kg-1
to 20.89 MJ kg-1
. Both tested processes significantly increased the fuel value of this
biodegradable waste
Evaluation of dried compost for energy use via co-combustion with wood
ArticleThere is still a question of utilization of compost of unsatisfactory quality. This article
deals with energy utilization of untreated compost. The energy utilization of raw compost as a
fuel is not directly possible without further processing. Separation
might be necessary due to large
amount of mineral content (soils and other inert substances).
This article is focused on the analysis of the basic fuel characteristics of compost. Proximate and
elemental analyses were performed and stoichiometric combusti
on was calculated. Finally, the
sample was co
-
burned with wood biomass in a fixed grate combustion device and the gaseous
emissions were determined in dependence on the amount of combustion air supplied. The
emissions were expressed in graphs against exces
s air coefficient and flue gas temperature.
Elemental analysis of the compost sample shows high percentage of ash up to 61.70% wt. on dry
basis causing low average calorific value of 8.51
MJ
kg
-
1
on dry basis. For combustion tests, the
heating value was in
creased by addition of wood chips to reach an average calorific value of the
mixture to 13.4
MJ
kg
-
1
. The determined stoichiometric parameters can help in optimization of
diffusion controlled combustion of composts or similar materials. In combustion of th
e mixture
of compost and wood biomass an optimum of emission parameters was found not exceeding the
emission limits. Measured emission concentrations show the possibility of optimizing the
combustion processes and temperatures while lowering CO emissions v
ia the regulation of
combustion air