I. Core Mechanism: During dry running, multiple factors converge simultaneously, causing salt crystals to rapidly precipitate and seize the impeller.

Without feed material to cool and dilute the mixture during dry running, the temperature in the pump chamber rises sharply in localized areas.

During normal operation, the continuous flow of high-salt mother liquor carries away frictional heat, keeping the salt content stably dissolved; During dry running, friction between the impeller, the medium, and the mechanical seal generates heat within seconds, causing the temperature in the sealed pump chamber to rise rapidly. This leads to the vaporization of trace amounts of water, causing the local salt concentration to instantly exceed the saturation threshold, resulting in the instantaneous precipitation of a large number of inorganic salt microcrystals.

The flow field stagnates; the microcrystals are not flushed by liquid and directly deposit and adhere

During material transfer, high-speed liquid flow generates strong shear forces, carrying away microcrystals before they can adhere; during dry running, the liquid inside the pump is nearly stationary, causing the newly precipitated fine salt crystals to directly settle and adhere to the impeller, gaps in the pump casing, and shaft sleeve crevices, rapidly accumulating to form a crystalline layer.

The interface between wet and dry zones accelerates crystal solidification and agglomeration

After running dry, the liquid level drops, and certain areas of the pump cavity are no longer submerged. The precipitated salt crystals lose their protective water film, rapidly dehydrate, and harden; when material is reintroduced, new and old crystals overlap and compact, causing the crystal layer within the gaps to thicken dramatically.

The pump’s tight clearances are easily filled and seized by crystals

The clearances between the impeller and pump casing, the shaft sleeve and seal gland, and the orifice ring are only a few tenths of a millimeter; even a small accumulation of microcrystals can fill these gaps. Due to the high hardness of the crystals and the absence of lubrication or cushioning, the impeller is directly locked by the hard salt layer, causing it to seize within seconds and resulting in motor overload.

Salt precipitation in concentrated mother liquor exhibits irreversible accumulation characteristics

The inorganic salt crystals precipitated from high-salt mother liquor possess extremely strong adhesion and cannot be washed away by water flow like sludge; once formed within the gaps, they are difficult to dislodge even with subsequent normal feed, continuing to thicken until the system is completely seized.