In plate evaporators, wide and narrow flow channels on the feed side exhibit significant differences in the patterns of fouling occurrence, rate of development, scale morphology, pressure drop changes, and self-cleaning capability under concentration and crystallization conditions. It is not simply a matter of one being prone to fouling and the other not; there are substantial differences in performance when handling salt crystals and flocculent sludge-like materials. Narrow-channel plates have small flow channel gaps, allowing for very high material flow velocities inside the channels and strong shear forces. In systems capable of uniformly forming fine salt crystals, the high-velocity feed stream can carry away most of the crystals, making extensive deposition and wall scaling less likely. However, these plates are highly sensitive to large crystal particles and agglomerated flocs. Even slightly larger crystalline clumps or flocculated sludge can easily become lodged at the inlet of the plate channels, causing bridging blockages. Blockages occur suddenly; while the pressure differential changes gradually in the early stages, once bridging occurs, the pressure differential spikes rapidly within a short time, directly causing a sharp drop in material circulation flow rate. Blockages tend to occur at the corners of the flow channel inlets; even when many areas of the internal flow channels are free of scaling, the flow is cut off by solids lodged at the inlet. Once a localized blockage occurs, no material flows through that section of the channel; the interior rapidly dries out, and the salt crystals harden due to high temperatures, making subsequent cleaning and disassembly extremely difficult. Narrow channels are better suited for concentrating salts with fine crystals and virtually no flocculent suspended solids; if the feed contains flocs or large crystal particles, the frequency of malfunctions will increase significantly. Wide-channel plates have larger gaps, making it less likely for solid particles to bridge and cause blockages; large crystalline chunks and flocculent sludge clumps can pass through the channels without instantly blocking the material flow path. However, under the same circulation flow rate conditions, the flow velocity of the material within the channels decreases, and the fluid shear force weakens. Salt crystals do not cause an instantaneous blockage but instead slowly settle and accumulate on the plate surfaces and at the bottom of the flow channels, resulting in progressive fouling. The pressure drop rises continuously and gradually, without sudden spikes. In the early stages, the equipment can still maintain operation, though heat transfer efficiency gradually deteriorates. The scale layer spreads over a large area on the heat exchange plates; the entire plate is gradually covered by crystals, which accumulate to increasing thickness, causing the effective gap in the flow channels to continuously narrow. In many cases, the equipment can still operate, making it difficult for operators to detect the issue immediately. It is often not until heat transfer efficiency has significantly declined and evaporation rates have dropped that operators realize the scale layer has already become quite thick. Wide flow channels are particularly vulnerable to prolonged low-load, low-speed circulation, as the further reduction in flow velocity rapidly accelerates the accumulation of sediment and scale. The two types of flow channels also present differences in cleaning procedures. In narrow flow channels, bridging blockages occur where scale deposits become lodged at the inlet. Chemical cleaning agents struggle to fully penetrate the blocked channels, and soaking and flushing have limited effectiveness; in many cases, the plates must be disassembled for manual cleaning. In wide flow channels, even with thick salt scale deposits, the cleaning agent can circulate freely within the channels. Online acid washing and soaking can reach most of the scaled surface, resulting in more effective chemical cleaning and a lower frequency of plate disassembly. In actual operation, mixed operating conditions may also arise. For narrow flow channels, if the crystal particle size is very fine, continuous operation at high flow rates may actually make blockages less likely; for wide flow channels, once the circulation flow rate is maximized to maintain a high flow velocity, crystal settling can also be significantly mitigated. The risk with narrow flow channels is sudden bridging that causes shutdowns, while the risk with wide flow channels is latent, slow scaling, where evaporation capacity gradually declines but is not easily detected in a timely manner. When selecting a design, if the feed solution contains flocs introduced during pretreatment or the crystal particles are relatively large, prioritize wide-channel designs; if the feed is clean and the crystal particles are fine, and heat transfer efficiency is the primary goal, narrow-channel designs may be selected—provided that the minimum circulation flow rate is maintained to avoid operation at low flow rates.