What is the crystallization temperature of concentrated sulfuric acid? How should winter crystallization be dealt with?

Thread Content

The temperature at which liquid sulfuric acid turns into solid sulfuric acid is called the crystallization temperature. The crystallization temperature varies with the sulfuric acid concentration, and this variation pattern is irregular. The crystallization temperature of 93% sulfuric acid is -27°C, while that of 98% sulfuric acid is -0.7°C. To avoid sulfuric acid freezing incidents in winter, an appropriate concentration of sulfuric acid should be selected based on the local climate conditions. In regions such as the northeast and northwest of our country, where winters are cold, if 98% sulfuric acid, which is prone to freezing, is to be produced, appropriate anti-freezing and insulation measures must be taken during its production, storage, and transportation to prevent potential accidents caused by crystallization in pipelines or sulfuric acid storage facilities. In winter, to prevent crystallization in the sulfuric acid storage tank, a heating strip can be installed on the surface of the tank, covered with insulation material, which is then secured from the outside using iron sheeting. When producing or transporting 98% acid, the pipes should be flushed with 93% acid, and the acid should be drained after flushing. During winter shutdown for maintenance, the remaining acid in the pipes should be drained to prevent crystallization from causing the pipes to crack. If acid accumulation occurs due to reasons such as insufficient slope in some sections of the pipes, resulting in pipe freezing, heating or steam should be used for thawing.