IceBlast process
In
ice blast, ice particles are accelerated by a stream of high velocity air
to do impact cleaning work. Ice particles are not free flowing and will
pack and agglomerate when static. For ice blast to work reliably, ice
particles must be created and consumed continuously in a dynamic state.
Equipment-wise,
it requires refrigeration and ice making. These are the two most reliable
industrial components today as our entire food supply infrastructure
depends on them. They can operate reliably under harsh climatic and
environmental conditions, even in third-world countries. The cost of ice
making is low as even local fish stores can afford it. In combination,
they have the attributes of a robust industrial process that is reliable
and cost-effective. In comparison, production of ice crystals by cryogenic
fluids is neither cost effective nor reliable in comparison. The most
reliable ice making process is known as “immersed cold drum”. (Figure
9). As refrigerant cools a rotating drum surface, a thin sheet of ice is
immediately formed. Under appropriate conditions of drum diameter,
temperature and rotational speed, the ice sheet can be formed with
sufficient internal stress that when its frontal edge impacts a doctor
blade, the sheet fractures into small ice fragments similar to the
shattering effect of a broken stressed (safety or Pyrex) glass.
Figure
9. Immersed Cold Drum for Ice Making.
Above
the doctor blade is mounted a tube with a longitudinal slot over the
entire length of the blade. One end of this tube is connected to a venturi-type
nozzle that draws by vacuum the ice fragments from the tube. The other end
of the tube is connected to a compressed air source that supplies
sufficient air to balance the vacuum created by the venturi. In this
manner, ice fragments are instantly fluidized and moved to the nozzle by
the induced flow. (Figure 10).
Figure
10. Ice Blast Process.
In
this process design, there is no mechanical intervention within the ice
particle production area. This allows ice particles to flow with no
interference. This process takes advantage of the natural fragmentation of
a stressed ice sheet to create particles and not rely on any mechanical
means to size them.
An
ice blast machine is therefore a collection of refrigeration, an icemaker
and a blast nozzle. These are proven commercially available components. To
operate an ice
blast machine, only standard utilities such as water, air and electricity
are required A typical ice blast machine uses 100 LPH of water, 15 KW of
electricity and about 8 M 3
/min
of compressed air. As ice particles disintegrate on impact, they create a
blast mist that helps to suppress dust from the operation and to cool the
environment for the workers. This is particularly helpful in the summer.
Evaporation will normally reduce the net liquid waste to about 10-40 LPH.