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Batch Sodium Hypochlorite System
Produce 1,000 - 3,000 Gallon Batches of Sodium Hypochlorite
The Powell Batch Sodium Hypochlorite System is based on our 40 plus years of experience
with bleach operations. The system is designed to produce 1000-3000 gallon batches of
sodium hypochlorite. The user will use chlorine from 1-ton containers or 150-pound
cylinders. The cooling tower, cooling water pump, recycle pump, filters, and heat
exchanger are supplied.
The purchaser supplies remote (not skid-mounted) PVC pipe, fittings, and valves,
since it is believed these can be obtained locally.
The basic principle of operation is to put water into the Powell recycle tank and
add 50% caustic until the strength of the caustic is approximately 6.75% (typical).
Within a few batches, the amount of water and amount of caustic to be added will
be established and then lines may be drawn on the tank to show the operators how
much water, and then caustic, to add.
The 50% caustic can be pumped into the tank or pulled into the system from the shipping
container or a storage tank by partially closing the recycle tank outlet valve and
opening the 50% caustic tank storage valve.
After the caustic is mixed, chlorine is added to the solution to react with the
caustic, except for a small amount of excess (0.2% by weight typical).
The final excess caustic endpoint is controlled by the batch controller. Sodium
Hypochlorite strength can be varied by changing the strength of the diluted caustic.
When the sodium hypochlorite has been made, the product can be pumped through the
final filter and then to a storage tank or the bottling line. Use of the filters
helps to ensure that the bleach product is clean and, with most of the solids removed,
it will be more stable and less oxygen will evolve from the bleach.
Almost all strengths of sodium hypochlorite can be produced with this batch system.
However, the high strength bleach above 11% may have to be cooled during storage
in order to keep the product stable. In some cases the cooling tower water may have
to be replaced with a small chiller to keep the bleach cool during production, although
normally that is not the case.
Once strong sodium hypochlorite is produced,
the bleach storage tanks can be chilled with a small plate and frame heat exchanger
using a recycle pump and a small chiller if required by ambient conditions.