Question

what is crystallization?how can you get urea from its solution?

Answer 1

Crystallization means that the solidification of atoms or molecules into a highly structured form called a crystal also refer to the solid-liquid separation and purification technique in which mass transfer occurs from the liquid solution to a pure solid crystalline phase. But if you cut out immediately, The solution is easy to block the pipeline. Also mentioned is how to prevent the crystallization of urea by-products. The urea crystallization of the by-product of urea is mainly formed after the reaction. They are difficult to dissolve into the water, forming a solid surface.

Answer 2

Crystallization is the process by which a solid forms, where the atoms or molecules are highly organized into a structure known as a crystal. Some of the ways by which crystals form are precipitating from a solution, freezing, or more rarely deposition directly from a gas. 
Crystallization of urea from an evaporative aqueous solution sessile droplet at sub-boiling temperatures and surfaces with different wettability