In the mixing process of fine materials (powder), Nitrogen usage is required and needed if what has to be treated is:
- combustible materials (Atex codes);
- hygroscopic products;
- biodegradable and oxidizing compounds;
- products to be thermally controlled.
The formation of a potential explosive atmosphere is a natural consequence of many industrial processes and activities. Using only nitrogen gas, it is possible to simply realize, under safety conditions, the pneumatic conveying and mixing of a variety of fine combustible materials (granular or powder). What should has to be performed is to maintain the oxygen concentration below the MOC level that is well defined for any different combustible fine materials.
Biodegradable and oxidizing compounds
The usage of Nitrogen gas, during the mixing phase, turns out to be one of the most effective secondary advantages in term of really extended “shelf life” of the managed products. With the substitution of air with pure nitrogen, the oxygen is no more present if not in a very low level. In such a ideal conditions, many organic substances easy to be biodegraded in presence of O2 are maintained untouched being their quality equal to the original: taste, flavour organolectic properties will be well uncorrupted.
Nitrogen, gas without moisture, if used instead of air with hygroscopic products, succeeds in perfect mixing, due to its fluidizing potential. This aspect ensure dis-aggregation of fine hygroscopic materials stored inside vertical silos. Because of any formation of lumps and bridges on the bottom of the silos (cone), an almost eliminated maintenance and plant failures are noticeable. All the classical needed operations, related to cleaning and restart up of clogged silos, using Nitrogen appear vague remembrances, as their frequency will have been strongly decreased.
Products to be thermally controlled
There are some specific applications,typically in food area, in which could be necessary, in addiction to mixing activities, also to control the temperature of the whole stored mass. In such cases, the nitrogen can be introduced in two different physical forms. Nitrogen gas as a source of mechanical energy, N2 liquid to decrease and control the temperature. Some temperature probes inside the silos, coupled with a specific software, regulate the optimal liquid nitrogen flow rate.Thermal control and fluidization effect are obtained, as for customer expectation.