In the industrial track of alumina production, evaporators serve as the core "power engines." Evaporator area and evaporation intensity are the crucial "accelerators" and "brakes" that determine how smoothly and quickly these engines operate. Industry experts have uncovered the truth behind these two parameters and found that there are significant issues hidden in the design methods commonly used by many enterprises!

Why does the area calculated by experience always "fail"?

Many factories are accustomed to using the empirical value of "evaporation intensity" to calculate the area of evaporators. In simple terms, it involves estimating the size of the equipment based on how much water can be evaporated per square meter. However, this "traditional approach" has frequently led to problems in actual production.

1.The "Pitfalls" of Empirical Values: The Same Calculation Method, but Different Results

An alumina plant in Shanxi put into operation an evaporator with a designed evaporation capacity of 370 tons. However, it could only evaporate about 220 tons per day, resulting in a production capacity reduction of nearly 40%! Why? It turned out that during the design process, the manufacturer took a shortcut by directly applying an empirical formula without considering the differences between its seven - effect evaporator and ordinary equipment. Each stage of a seven - effect evaporator has a smaller temperature difference, requiring a larger "heating surface" for heat transfer. But the empirical calculation method failed to account for this factor, resulting in an insufficient evaporator area. As a result, heat cannot be effectively transferred, and water evaporation is severely hindered.

2. Cognitive Misconception: Must the Area of a Single - Effect Evaporator be Large?

In the past, it was commonly believed that the area of the first stage (first effect) of an evaporator must be larger than that of the subsequent stages. Two 500-ton evaporators in an alumina plant in Hebei Province fell victim to this misconception. Designed based on traditional experience, the equipment malfunctioned during the summer. Although it could barely operate in winter, the evaporation capacity dropped sharply as soon as summer arrived. Upon closer inspection, the problem was found in the heat balance calculations: the plant had miscalculated the evaporation capacity of the last stage (final effect), resulting in an insufficient supply of cooling water. As temperatures rose in summer, the vacuum inside the equipment could not be maintained, and the evaporation efficiency was halved.

Heat Balance Calculation: The Secret Weapon to Revive Evaporators

Since the empirical method is unreliable, how can we design evaporators accurately and effectively? The answer lies in heat balance calculations. This is like giving the evaporator a comprehensive "physical examination," precisely calculating how much heat enters, how much heat exits, and how water evaporates.

Take the alumina plant in Shanxi as an example. Later, they redesigned the evaporator using heat balance calculations and found that to achieve an evaporation capacity of 370 tons, the equipment area needed to be increased by 20% compared to the original design. After the adjustment, not only did the equipment meet the production target, but the steam consumption also decreased by 15%. The cost savings in one year were enough to purchase several new sets of equipment!

Let's take a look at the case in Hebei. The manufacturer corrected the evaporation volume value of the final effect, recalculated the cooling water volume, and "prescribed the right medicine" for the equipment. After the renovation, even during the hottest days of summer, the vacuum level of the evaporator remained stable, and the evaporation volume has never fallen short again.

From "Gut Feeling" to "Precise Calculation": A Major Transformation is Underway in the Industry

Nowadays, more and more enterprises have come to realize that evaporator design can no longer rely on "approximate" experience but rather on scientific calculations. Many factories have started to build their own "data treasure troves," recording equipment data under different concentrations and temperatures. As a result, the calculation error has decreased from the original 15% to 3%. Additionally, some enterprises use professional software to simulate equipment operation, reducing the design cycle from 45 days to 22 days, effectively doubling the efficiency!

In the highly competitive alumina industry, every square inch of an evaporator holds real value. The transition from "empiricism" to "data - driven" approaches is not just a technological upgrade; it is a revolution in thinking. As an engineer once said, "To ensure that the equipment doesn't hold back production, every single data point must be put to use!"