Seven-effect two-stage evaporator

During the operation of the entire evaporation system, the secondary steam produced by each effect evaporator can serve as a heat source for the next effect, realizing tiered utilization of thermal energy. Inside each evaporator, the solution achieves continuous evaporation and concentration under the heating action of steam. Taking the common seven-effect two-stage countercurrent process as an example (seven-effect tubular falling film evaporator, five-stage self-evaporator, original liquid flash evaporator), this process employs a two-stage evaporative countercurrent operational model. The first stage comprises the original liquid flash evaporator, VII effect, and VI effect; the second stage consists of V effect, IV effect, III effect, II effect, I effect, and four-stage flash evaporator. The evaporative feed liquid is divided into two parts entering the evaporation system. One part of the feed liquid enters through the original liquid flash evaporator and after evaporation concentration through VII effect and VI effect, it exits from VI effect. The other part enters through V effect and is consecutively evaporated and concentrated through IV effect, III effect, II effect, I effect, first, second, third, fourth, and fifth stage flash evaporators, exiting from the fifth-stage flash evaporator. This two-stage design can better accommodate the characteristics and process requirements of different solutions, significantly enhancing energy utilization and evaporation efficiency.

Technical Advantages
01. Energy-saving and efficient: The seven-effect evaporation design, combined with the two-stage process, demonstrates exceptional performance in energy utilization, placing the energy-saving seven-effect two-stage falling film evaporator technology at the world's leading level. Compared to traditional evaporators, it can significantly reduce energy consumption and operational costs. For instance, in large-scale alumina production processes, it can provide substantial long-term savings in energy expenses for enterprises.
02. Patent-backed technology: Around this evaporator, Jiuyie Chemical has conducted in-depth research on membrane distributors, foam removers, new types of evaporative condensers, and the complete recovery of high-quality condensate, applying for over 30 patents. These patented technologies optimize the performance of the evaporator at various stages, such as a precise membrane distributor ensuring uniform distribution of the solution on the heating surface, enhancing evaporation efficiency; an efficient foam remover effectively separating droplets in the steam, ensuring steam quality; and a new evaporative condenser enhancing condensation effects, improving overall operational stability.
03. Adaptability to complex needs: The modular structure allows for flexible responses to different production sites and process conditions. For factories with limited space, various modular devices can be arranged flexibly; for materials with different characteristics, whether high viscosity, prone to crystallization, or thermosensitive solutions, stable and efficient evaporation and concentration can be achieved through optimized process flows.
Application Fields
Alumina Industry
In alumina production, the size of the evaporator heating chambers increases as production capacity rises, presenting challenges in manufacturing, transportation, hoisting, and installation. In response, Jiuyie Chemical applied for the patent product “Falling Film Evaporator with Multi-Heating Chamber Structure” in 2021 and received authorization, successfully implemented in the 1.2 million tons alumina project of the Jinjiang Group at the Qianxinx Chemical Co. in Tiandong, Guangxi. The seven-effect falling film evaporator adopted in this project has an average evaporation capacity of 580t/h, with a maximum capacity of up to 630t/h; if using the low-concentration trihydrate soft bauxite process, the evaporation capacity can reach 700t/h. This evaporator successfully solves related challenges of super-large diameter heating chambers, significantly promoting industry development.
Other Industries
In addition to the alumina industry, this evaporator is widely applied in paper making, wastewater treatment, bioprocessing, food production, chemical industry, pharmaceuticals, and salt production. In the paper industry, it is used for the evaporation and concentration of black liquor from pulp, achieving resource recovery and environmental protection; in the food industry, it evaporates and concentrates juices, syrups, etc., preserving the nutritional components and flavors of the food.
For many years, Jiuyie Chemical has produced dozens of different specifications of products for major aluminum companies both domestically and abroad utilizing the seven-effect two-stage modular evaporator, maintaining good operational status, with technical indicators far exceeding design values, receiving numerous positive reviews from customers, demonstrating the reliability and advancement of the product in practical applications.