Integrierte Vermeidung und Verminderung der Umweltverschmutzung

Chapter 3
3.2.52.3 Solid output
Ashes from solid fuel fired boilers and scale and inert soot deposits which are removed during
periodic boiler maintenance and cleaning, are produced. They are sent for landfill.
3.2.52.4 Noise
Normal boiler operations do not give rise to noise outside the installation, but this depends on
the measures taken to contain the noise and the proximity of neighbouring premises. During
process interruptions, and during periods of testing and commissioning, there may be short
periods when the boiler safety relief valve operates. This effect is likely to be local to the
installation but could be a source of nuisance during that period. Large relief valves can be
provided with silencers.
3.2.53 Water use (U.3)
3.2.53.1 Water
Waste water from water regeneration and residues from other processes are discharged to water.
Minimisation of water consumption by process optimisation and water recycling can be applied.
3.2.53.2 Solid output
Mineral sludges and spent resins from water treatment processes need to be disposed of.
3.2.54 Vacuum generation (U.4)
3.2.54.1 Water
Water is used in water-ring type vacuum pumps for cooling and for sealing. To reduce water
consumption, the water is normally recirculated in closed-circuit systems with a bleed off
determined by the condensable matter. Waste water is produced which contains soluble organic
material.
If steam jet ejectors are used for vacuum production, not only the media coming from the
evacuated plant has to be condensed, but also the driving steam of the jet ejector. This is
normally done in spray condensers. Here, water is used to condense the steam along with any
volatiles carried over. For large installations, the volume of water used to condense the steam
can be significant, i.e. during refining of sugar or edible oil. The volatile material carried over is
condensed in the water thereby increasing the level of dissolved organic material. To reduce
water consumption, water can be recirculated over cooling towers. In this case a bleed from the
system is required for the condensed steam. This can lead to a concentration of the organic
material condensed in the water. With indirect condensers or heat-exchangers, the volume of
condensate is equivalent to the condensed live steam and other condensable matter, and will
contain any organic volatiles carried over. With chilling or freezing systems, the volume of
condensate is reduced further.
3.2.54.2 Air emissions
Depending on the material being processed, air evacuated by vacuum pumps may contain
volatile material, which, if not properly controlled, may result in odour problems.
Non-condensable material may be discharged into the air with steam jet ejectors. Depending on
the material being processed, this discharge may result in odour emissions. If condenser water is
recirculated over cooling towers, the drift/mist from the towers may result in odour emissions.
Indirect recirculation with heat-exchangers with two cycles may be used in this case. Heatexchangers
have to be cleaned regularly.
146 January 2006 RHC/EIPPCB/FDM_BREF_FINAL