Process points of falling film evaporation technology
1. Process flow design
The process flow design of the falling film evaporator is a key factor affecting the concentration effect. Common processes include downflow, countercurrent, mixed flow and flat flow.
In the downstream process, the solution and steam flow in the same direction make it suitable for dealing with heat-sensitive materials, especially in the case of high concentrations of good performance.
Countercurrent processing is a method of processing liquids and steam that involve the use of temperature and concentration changes to modify the viscosity of the solution. The raw materials are liquid and steam, which flow in opposite directions.
A mixed flow system integrates the benefits of both downstream and countercurrent processes. However, it should be noted that the operational complexity of this system is significant and places high demands on automation control systems.
Flat flow: all effects are fed and discharged, making it suitable for the evaporation of saturated solutions.
2. Please ensure that the preheat is preheated and that the preheat is graded.
Preheating is an essential step in the process of falling film evaporation. It has been shown to enhance evaporation efficiency and reduce energy consumption. For instance, in the concentration process of maltose syrup, the implementation of dilute solution preheating at a gradual rate, in conjunction with the utilisation of low-temperature steam for incremental preheating, has been demonstrated to result in substantial reductions in steam consumption.
3. The process is subject to precise regulation of temperature and pressure.
Precise control of temperature and pressure is crucial to the effect of falling film evaporation. The process of producing maltose syrup necessitates precise regulation of the temperature of the heating and evaporation chambers. For instance, in the four-effect falling film evaporation system, the temperature of the heating chamber of the first effect is set at 105°C, and the solution temperature of the evaporation chamber is 96°C; the temperature of the heating chamber of the fourth effect is 76°C, and the solution temperature of the evaporation chamber is 68°C.
4. Control of both the flow rate and the liquid level is essential.
Ensuring the stability of flow rate and liquid level is crucial for maintaining a seamless evaporation process. The automated control system enables real-time monitoring and adjustment of syrup flow and liquid level, ensuring the stability of the evaporation process.
Quality control points
1. Syrup concentration control:
- Ensure that the final concentration of the maltose syrup meets the process requirements by precisely controlling the temperature, vacuum and flow rate during evaporation. For example, the syrup is concentrated from 43.3 per cent to 82-83 per cent.
- The concentration of the syrup is regularly checked to ensure that it is within the specified range .
2. Prevent scaling and clogging:
- Maltose syrup is prone to scaling during evaporation, which affects heat transfer efficiency. Therefore, the evaporator needs to be cleaned regularly to keep the heating tubes clean.
- Use suitable cleaning agent and cleaning process to ensure the cleanliness of the inner wall of the heating tube .
3. Product quality monitoring:
- During the evaporation process, the colour, transparency and impurity content of the syrup need to be monitored to ensure product quality.
- Ion exchange and decolourisation processes are used to remove impurities and colours from the syrup to improve product quality.
Conclusion
The falling film evaporation technology has significant advantages in maltose syrup concentration, through reasonable process design and strict quality control, it can effectively improve the production efficiency, reduce energy consumption, and at the same time ensure product quality. With the continuous progress of technology, the application of falling film evaporation technology in the field of maltose syrup concentration will be more widely used.