Trouble-free storage, pneumatic conveyance and metering of hygroscopic bulk products, example: urea
The storage of hygroscopic bulk products in larger vessels/silos frequently causes problems such as clumping and encrustations, up to and including complete blockage. In 1978, the solids solutions group constructed the first outdoor metal silos for urea and granulated sugar, the provisions implemented then resulting in trouble-free operation and retaining their validity even today. Pneumatic conveyance, vibratory bowls with integrated cutters for discharge of Big Bags and a vibratory grid integrated into the silos are, as plant-engineering solutions, of an importance equal to that of adherence to the specified product and ambient temperatures and relative air-humidity in filling of silos with hygroscopic bulk products.
1. Introduction
Urea, due to its extremely pronounced capacity to absorb and fix water, is classified as highly hygroscopic. The product is an important nitrogen fertilizer, and is also used industrially as a binder in insulating panels and chipboards, for example. It has also recently come into use for the reduction of oxides of nitrogen in the exhaust gas emitted by motor vehicles, and in the use of substitute fuels, in the cement industry, for instance. Urea is injected in solution into the hot exhaust flow downstream internal combustion engines, where it reduces the oxides of nitrogen in...
