The steam supplied to the equipment for three-effect evaporation will decrease

It is likely that too much feed was added in a short period of time, causing the temperature of the liquid in the first stage to drop below the evaporation temperature; as a result, the amount of evaporation decreased, and consequently there was less secondary steam in the first stage； This matter needs to be considered from two aspects: ① Is there a problem with your material feeding control? ； ②If the high salt content leads to a large feed volume, or if the low temperature after preheating is the cause, then an additional steam heat exchanger stage must be added for reinforcement. In short, it is necessary to ensure that the liquid temperature of the material in the evaporation chamber remains consistently above the evaporation temperature

It is the reduction in primary steam (the steam entering the shell-and-tube exchanger in the first stage), not the reduction in the secondary steam from the first stage.

Do you also have problems with steam generation?

Preheat the feed pumped to the first stage to the operating temperature of that stage

There were no similar situations before; could there be a problem with the equipment?

What does steam reduction refer to – a reduction in temperature or pressure? It is normal for temperature and pressure to drop, as the material entering the equipment needs to be preheated; to reach the boiling point, steam is consumed, which leads to a decrease in temperature and pressure.

The pressure is reduced, and the temperature of the material is around 50 degrees. Before it is pumped into the first stage, it is preheated using two plate heat exchangers; however, these plate heat exchangers use condensed water for heating rather than steam, with steam being used only to heat the shell-and-tube heat exchangers in the first stage.

If the steam pressure remains unchanged, it indicates that steam is being trapped; a decrease in pressure suggests that steam is being consumed. If the boiling point of the material being evaporated increases, the material enters the evaporator after preheating, and at this point there is room for the material concentration to decrease as it evaporates, which in turn leads to steam consumption. A decrease in steam pressure is therefore a normal phenomenon. As the material concentration increases and its boiling point rises, the amount of evaporation decreases slightly, and steam consumption slows down. At this point, steam may again become trapped, meaning that the pressure stabilizes once more. The introduction of new material often results in a decrease in steam pressure. It is necessary to consider the overall operation of the entire equipment to determine whether such phenomena are normal.

It seems to be a problem with the low temperature of the raw materials. Also, for shell-and-tube heat exchangers, is it better to keep the valve at the steam non-condensable gas outlet open wide for better heating effects, or should it be kept closed to achieve better heating results?