In the production of paraformaldehyde and polyoxymethylene, high concentrations of formaldehyde are required as raw materials. But the normal formaldehyde production, whether it is silver or iron molybdenum, the product concentration is not more than 55%. So the need for raw materials for dehydration dehydration enrichment, and enrichment process will produce dilute formaldehyde. Dioformaldehyde is usually used to produce downstream products (such as urotropine, methylal, etc.) that are not required for formaldehyde feedstock concentrations and enrichment and recycling.
Commonly used dilute formaldehyde concentration recovery technology there are two, respectively, decompression flash separation process and pressurized distillation enrichment process. The former in the concentration process will once again produce about 8% of the dilute formaldehyde; the latter can be recovered 36-46% of the formaldehyde solution, but in the pressurized distillation process, with the increase in pressure, formaldehyde prone to disproportionation reaction Formic acid, which will not only cause formaldehyde loss, more importantly, formic acid will seriously corrode the equipment, although this problem can be selected by the higher grade of special steel to solve, but the investment will be too high, very economical.
I company dilute formaldehyde enrichment recovery technology, in the pressurized distillation method on the basis of the process and equipment, such as internal technical improvements, resulting in reduced corrosion, equipment investment reduction, and integrated with the tower and tower Heat load, production and energy consumption greatly reduced.
95 tons / day 22% dilute formaldehyde concentrated recovery as an example.