Cleaner Production in Jeans Laundries in Northeast Brazil - Implementing Environmental and Resource Management - page 85

Fig. 9.2. Old steam boiler and furnace (source: photo taken by the author)
Given the high water consumption, more advanced strategies for increasing en-
ergy efficiency have to consider measures to reduce the amount of fuel used to
produce steam. An analysis of the distribution of required water temperatures re-
veals that 54% of the total water consumption refers to 'cold water', i.e. water of
ambient temperature. A further 31% describes water with temperatures in the
range of 40 to 60°C. Under these conditions, two very promising options exist.
First, heat exchangers could be used to preheat water entering the machines by the
remaining heat of the effluent. The second option includes the application of solar
energy to produce hot water.
Regarding the first option, Baudach (2007) refers to a theoretical potential to
reduce energy consumption of up to 40% by installing heat exchangers. The main
obstacle lies in the complexity of applied washing processes, which complicates
the separation of the used water. Another low-cost possibility could be using heat
energy of the gas leaving through the furnace chimneys in order to preheat water
before entering the boiler. In any case, the area of reusing heat energy deserves
more research.
The second option, using solar collectors, might be even more promising and
also a visible sign of a more 'ecologically correct laundry', at least in terms of en-