The difference between different evaporator effect numbers

Multi-effect evaporation and concentration systems are designed to maximize steam efficiency and reduce energy consumption. The key characteristic of these systems is that the more effects (stages) added, the greater the steam savings. For example, with N effects, 1.2 kg of steam can evaporate N kg of water, meaning that evaporating 1 kg of water requires only 1.2/N kg of steam.

In practical terms:

- A two-effect system requires 0.6 kg of steam per kg of water.

- A three-effect system requires 0.4 kg.

- A four-effect system requires 0.3 kg.

However, increasing the number of effects also increases the heat transfer area required, which can make the system less economical beyond a certain point. Additionally, as the number of effects increases, the temperature difference in each stage decreases, limiting the feasibility of further expansion.

Typically, multi-effect extraction and concentration equipment, such as those produced by Hangzhou Huihe Machinery, uses a four-effect system. While some industrial evaporators can achieve up to seven effects, the trade-off between steam savings and equipment cost generally makes four effects the most practical choice.