A key product of the chemical industry, caustic soda
is commonly produced by electrolysis of brine solution
through membrane cells. The resulting low concentration caustic soda
(32% NaOH) can be concentrated up to 50%, 73% or even to solidification (99.5%
NaOH or higher) to be used in a wide range of applications, such as pulp and
paper, cellulose based textile, alumina, soap, detergent, cleaners and many
others.
Our know-how acquired over almost a hundred years in the
chlor-alkali industry, starting with the diaphragm and mercerising caustic soda
field, our wide experience in many process industries and our expertise in heat
transfer allow us to provide an optimised design of caustic soda concentration
units.
Compact and modular, caustic soda units are well suited to the
skid mounted conception : easy to transport, they require few manpower to set
up and run on.
Facing highly corrosive properties, it is important to
choose the right material, suitable for a long life and safe plant operation.
Factors enhancing corrosion risk such as high temperature, mechanical stress
and specific impurities must be taken into account when designing the unit.
Kestner has successful experience with different materials such as Nickel 200
and 201, Incolloy 825, stainless steel 316 L and 304L, etc …. Low metal content
in the concentrated caustic soda is therefore guaranteed.
Anhydrous
concentration of caustic soda is among Kestner‘s strengths. From 32% or 50%
NaOH, with a possible 73% NaOH intermediate step, we are able to concentrate
the caustic soda up to 99-99.5% with climbing and falling film evaporators. The
resulting high quality of the product allows the production of flakes,
pastilles and prills. The recommended process ensures a smaller boiler size and
minimum energy consumption.
Reaching temperature higher than 350°C,
anhydrous caustic soda is not easy to treat : Kestner is used to dealing with
complicated parameters such as material choice, good control of heating media
and transfer of very high freezing point solutions.
Kestner is also
well known to provide calcium chloride
concentration and crystallisation units.
