Industrial paraformaldehyde takes dilute formaldehyde solution as raw material, evaporates under reduced pressure, condenses in the presence of a catalyst, and then filters, washes and vacuum-drys to obtain finished products.
Among them, the vacuum drying process is more critical, and there are two types of rake vacuum drying and spray drying.
The product produced by spray drying has uniform particles and good solubility, which is dominant.
Chemical Reaction Equation: nCH2O- (CH2O)n
Each ton of solid formaldehyde consumes 3.18 tons of 37% formaldehyde solution.
The main production equipment includes: thickener, condenser, evaporator, filter, dryer, fan, pump, etc.
The principle of paraformaldehyde production process
1. Formaldehyde solution is easy to polymerize under concentrated or low temperature conditions. The higher the concentration of formaldehyde, the easier it is to polymerize.
2. It is easy to depolymerize under high temperature or dilution conditions;
3. Step-by-step control and concentration of industrial formaldehyde;
4. Concentration trend: transition from relatively low temperature and high vacuum to high temperature and low vacuum;
5. Relatively high temperature before granulation.
