problems in the candy factory 1

[mike8181]

I have a problem with the scaling of pipes (carbonate,chalk.lme formation). The water tests show that the ph is ok, german hardness is ok . Also theres a blackening of stainless steel r 316 L and corrosion of the injection moulding press which is made of a cu-al-ni-fe alloy. I use sodium hydroxide as the cleaning agent and a boost of hydrogen peroxide to clean the pipes and the stainles steel tanks. My suspects are the resin udes in the softening unit bayer lewatit s 1467 and the composition of the naoh / h2o2 mixture , maybe i need the correct mixture , i want to know the ideal mixture of naoh and h202 for cleaning 5000 litre tanks and the correct resin for the softening unit.
The water used for cleaning is normal room temperature , the process water is 85 c . The pressure is 3 bar , velocity of water is 3ft/sec. The flow is not turbulent, i know that this type of flow causes scaling. The water used for cleaning is softened water ph 8-9 , german hardness 3.5 , I also understand that there should be some amount of hardness in process water as this develops a protective barier above the surface of the metal.My company is in the netherlands and I have contacted the ppl who make the press about the alloy , apparently its a popular choice. There is no substitute for the h202 , so im really clueless. The softening unit manufacturers claim that their unit works well and the water tests prove that the water entering and leaving the unit is ok.

 

[sshep]

I am curious about the view that water hardness is desirable for passive film formation, usually lower is better for any heat transfer application.

I feel you should be checking your softening process further. I didn't even find Lewatit S1467 resin on their website.

best wishes,
sshep

 

[mike8181]

its s 1468 , i mentioned s 1467 as purolite suggested their pfc 100 is similair to s 1467 , btw the problem is solved , it was the softening unit (though lubron doesnt want to accept that) and the combination of detergents naoh+h2o2..