In the alumina production process, as a core piece of equipment, the performance of evaporators directly affects a company's production costs and efficiency. However, multiple enterprises, including an alumina company in Hebei, one in Shanxi, and another in Chongqing, have successively encountered production difficulties due to evaporator problems. Behind these cases lie numerous easily overlooked "pitfalls" in the evaporator selection process. In particular, errors in heat balance calculations have become a "fatal blind spot" in equipment selection for the industry. It is extremely urgent for alumina enterprises to conduct in - depth analyses of these cases and summarize strategies for avoiding these pitfalls.

I: In - depth Analysis of Typical Cases

01: A 500-ton evaporator of an alumina company in Chongqing encountered the dual problems of insufficient evaporation volume and soda leakage in the final effect during operation. Field inspections by our technical team revealed that the temperature of the cooling water discharge reached as high as 57 degrees Celsius in April, and the actual evaporation volume was only a little over 430 tons. Upon verification, there was a serious deviation in the calculation of the evaporation volume of the final effect by the manufacturer. The erroneous value of 81 tons differed significantly from the actual requirement of 140 tons. The cooling system and the size of the separation chamber configured based on the incorrect data made it difficult to maintain the vacuum degree and resulted in poor gas-liquid separation, thus leading to the failure to meet the evaporation volume standard and the occurrence of soda leakage. If enterprises fail to pay attention to the accuracy of heat balance calculations during the equipment selection process, they are highly likely to fall into similar equipment performance dilemmas.

02: Looking back at the cases of an alumina company in Hebei and another in Shanxi, equipment performance defects were also triggered by errors in heat balance calculations. For a 370-ton evaporator of an alumina company in Shanxi, the manufacturer calculated the heat transfer area using empirical values of evaporation intensity, failing to fully consider the characteristics of the seven-effect evaporator. This led to insufficient heat transfer area, and the production capacity never met the standard. As for a 500-ton evaporator of an alumina company in Hebei, miscalculation of the evaporation volume at the final effect and improper configuration of the cooling water volume caused a drop in vacuum degree during summer and a sharp reduction in evaporation volume. These cases repeatedly demonstrate that errors in heat balance calculations are the "number one trap" in evaporator selection.

II: Focus on Heat Balance Calculations: A Guide to Avoiding Pitfalls in Evaporator Selection

So, how can alumina enterprises avoid these "pitfalls" when selecting evaporators?

Firstly, enterprises should abandon the mindset of "empiricism" and refrain from relying solely on the equipment manufacturers' past cases or simple parameter comparisons. Heat balance calculations require customized designs that integrate the enterprise's own raw material characteristics, production processes, operating conditions, and other factors to ensure that the equipment is tailored to actual production needs.

Secondly, when communicating with equipment suppliers, enterprises must request them to provide detailed and comprehensive heat balance calculation reports, including the calculation processes and bases for parameters such as temperature, pressure, flow rate, heat transfer area of each effect, and evaporation volume of the final effect.

In addition, enterprises should give priority to suppliers with extensive experience in designing evaporators for the alumina industry and proficiency in advanced heat balance calculation techniques. It is essential to assess the professional backgrounds of their technical teams and the outcomes of their past projects, so as to prevent selection errors caused by insufficient supplier capabilities.

The "pitfalls" in evaporator selection often lurk in the details, and heat balance calculation is the crucial detail that determines the success or failure of the equipment. Only by attaching great importance to heat balance calculations and maintaining a rigorous and professional attitude during the selection process can alumina enterprises select evaporators with reliable performance. This approach helps them avoid falling into a vicious cycle of equipment failures, production disruptions, and rising costs, thus laying a solid foundation for the efficient and stable operation of their production processes.