Are the plates burned when changing boards?
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Replace it with another plate that is not commonly used (material Ni201, 50% alkali solution on one side, circulating water on the other side. Circulating water cools the alkali solution. The heat exchange temperature is not greater than 200℃) remove the plate and replace it with another plate of the same model (material LC-Ni/CS, 39% alkali liquid on one side, steam condensate on the other side. The steam condensate heats the lye. Heat exchange temperature 170℃). After using it for less than a month, the following phenomenon occurs. What is the reason?
It is caused by the accumulation of impurities in the alkali solution. Generally, there is a filter before replacing the plate, right?
The scale is so severe that it seems that it is not suitable for plate replacement or that it needs to be cleaned and swept regularly?
It feels like it was replaced by steam, and then the steam flow rate was high, causing the plate replacement (as can be seen in the last picture) to wear out the steam inlet hole, and it was no longer able to buffer the steam impact. This causes local overheating of the plate close to the inlet hole, resulting in this burning phenomenon. Don't know if that's the case.
We have done similar working conditions. The alumina plant used to heat lye to boil the scabs in the pipes. The lye concentration is around 40, and the shell-and-tube type is used. In your working condition, like liquid-liquid heat exchange, plate exchange is very good and the heat exchange efficiency is high. However, for such high temperatures, it is best to use shell-and-tube type. For example, we are doing spiral winding with very good results. It is convenient to add a WeChat chat, qsxs888888
This situation should be caused by corrosion. It is possible to check the corrosion rate of alkali solution at different temperatures and the corresponding material selection.