Environmental Engineering Reference
In-Depth Information
sive as the use of fire wood (less than 0.08 R$ per pair of jeans). Even though a
difference of 0.09-0.10 R$ in specific costs might be not that huge, given a
monthly output of 100,000 jeans, it amounts in an increase of fuel costs of ap-
proximately 9,360 R$ compared to the use of wood.
One of the medium sized laundries in Caruaru switched from fuel wood to ba-
gasse pellets. It was possible to observe their laundering process for one day. In
total, 241 pieces of jeans were washed, resulting in the consumption of 240 kg of
bagasse and 13,000 litres of water. For this company, specific fuel costs amount to
0.21 R$ per pair of jeans. It is however difficult to say in how far this represents a
typical average value. Nevertheless, this laundry serves as example that the use of
bagasse seems to be economically feasible.
9.4.2 Energy Flows and Losses in Laundries
Based on an analysis of one of the biggest laundries, typical examples for energy
losses will be presented. It has to be noted that the situation in many of the
smaller, less-organized laundries is often worse. Besides the lack of knowledge,
for many owners it seems to be simply not attractive to invest in measures to im-
prove energy efficiency. Firewood is quite cheap in absence of control by authori-
ties. Especially in smaller laundries, old boilers with combustion efficiencies of
60% or even below are still in use. More advances steam boilers typically have
combustion efficiencies of 70-80%. The main problem is excess of air during the
combustion process (Baudach 2007). Furthermore, the overcapacity of many boil-
ers in use contributes to lower efficiency. The above mentioned boiler systems
consist of a furnace and the actual boiler part (see
Figure 9.2
). In latest-developed
devices available on market both functional parts are combined, reducing addi-
tional heat losses. Therefore, replacement of the older boiler by models of the
newest generation with an adequate capacity might improve energy efficiency
considerably.
Furthermore, in many laundries steam tubes from boilers to washing machines
and driers are either incompletely or not at all insulated, which leads to significant
and unnecessary losses of energy. In cases where tubes are insulated, very often
valves and connections lack insulation. Particularly in smaller and less-organized
companies, tubes are unnecessarily long and not insulated at all. Proper insulation
is neither complicated nor requires high investment costs. It contributes signifi-
cantly to the improvement of efficiency and thereby offers benefits for the entre-
preneurs as well as for the environment. Due to insufficient awareness and cost
controlling by the owners, this point often receives no attention at all.
Additionally, Baudach (2007) mentions the potential for reducing the amount
of steam and electric energy used for the driers by avoiding too long drying proc-
esses. Installing control technology with sensors for temperature and humidity al-
lows the stopping of the drying process automatically once threshold values have
been reached. Further, employing heat exchangers allows for the use of heat en-
ergy contained in exit air in order to preheat air entering the machines.
Search WWH ::
Custom Search