During the operation of evaporators, "excessive alkali carry-over in secondary water" is a tricky problem frequently encountered by many enterprises — sometimes the operating parameters seem normal, but the alkali carry-over amount suddenly increases, leaving people at a loss. Recently, Director Ju, a senior expert in the industry, has conducted an in-depth sharing session regarding this issue. Covering everything from design principles to practical operations, he explained the key underlying causes clearly and thoroughly, and today we will take everyone to learn about it together!

I. Core Crux: Don’t Let "Overload Operation" Undermine the Evaporator

Director Ju emphasized that when the alkali carry-over in secondary water fluctuates (sometimes high, sometimes low), the root cause often lies in "operational overload". The design parameters of evaporators are all precisely calculated, and once the actual operation exceeds the rated capacity, the alkali carry-over issue is prone to occur. Specifically, there are two common scenarios that lead to overload, and everyone can check against these to identify potential issues:

1.Excessive Steam Temperature: Temperature difference widens, leading to a "false high" in production capacity

When designing an evaporator, a reasonable steam temperature range is clearly defined. However, in actual production, there are cases where "the steam temperature is higher than the design value" — this directly causes the temperature difference inside the evaporator to widen, the evaporation rate to accelerate, and the production capacity seems to increase, but it has already exceeded the equipment's rated capacity.

Why does this cause alkali carry-over? Director Ju explained: The diameter of an evaporator’s separation chamber is designed based on the rated capacity. When the production capacity exceeds the limit, the "empty tower gas velocity" inside the separation chamber will increase accordingly. An excessively high gas velocity, like a "strong wind", will sweep droplets of the alkaline solution into the secondary water, resulting in excessive alkali carry-over. Therefore, do not blindly pursue "high production capacity"; when the steam temperature exceeds the design value, timely adjustment is the key.

2.Excessive Stock Solution Temperature: Flash Evaporation Amount Surges, Leading to "Out-of-Control" Production Capacity

Besides steam temperature, the temperature of the stock solution also affects production capacity. If the stock solution is overheated during the heat exchange process (resulting in excessively high temperature), it will generate a large amount of flash steam after entering the evaporator — as soon as the flash evaporation amount increases, the evaporation capacity will also "passively increase" accordingly. At this point, if one still insists on "holding onto high production capacity" and continues to maintain excessive operation, the risk of alkali carry-over in secondary water will rise sharply.

II. Key Countermeasures: Strictly Control Production Capacity and Uphold the "Rated Red Line"

Since overload is the main cause, the solutions naturally need to focus on "controlling production capacity". Director Ju has provided specific operational recommendations:

For cases where the stock solution temperature is excessively high, one can utilize the evaporator’s "two-stage design" — focus on controlling the flow rate of the stock solution entering the flash steam stage, stabilize the overall production capacity "within the rated value" (preferably ≤ the rated capacity), and avoid pursuing large production capacity beyond the equipment’s load-bearing range for an extended period.

To put it simply: Do not be greedy for excessive capacity or exceed the limits; keep the evaporator operating in its designed "comfort zone," and the issue of alkali carry-over in secondary water will be significantly reduced.

Summary: Don’t let "high production capacity" cover up "high risks"

Director Ju’s sharing actually reminds us that the operation of an evaporator emphasizes "following the rules of operation" rather than "pursuing forced breakthroughs". The rated capacity is not a "restraint" but a "protective line" for the stable operation of the equipment — when there is excessive steam temperature or excessively high stock solution temperature, it may seem to increase production capacity in the short term, but in reality, it will disrupt the gas velocity balance in the separation chamber, leading to recurring alkali carry-over issues.

Going forward, when everyone encounters excessively high alkali carry-over in secondary water again, you may first check: Is the steam temperature exceeding the design value? Is the stock solution temperature too high? Has the production capacity exceeded the rated range? If you keep these key points under control, the evaporator will operate more stably, and the production efficiency can also be more sustainable.