Vacuum evaporation of milk has a lot of advantages. This process allows water to evaporate at lower temperatures, which reduces the risk of denaturation of milk proteins and preserves its taste. In addition, vacuum evaporation reduces the consumption of coolants (steam and water), which makes the process more efficient and economical.
Also, vacuum evaporation helps to remove trapped air from milk, improving curd stability and reducing syneresis during storage. This makes it the preferred method for producing condensed milk and other dairy products that require concentration. A specialized vacuum evaporator is best suited for evaporating milk under vacuum conditions. It allows you to effectively remove water from milk at low temperatures, which preserves its taste as well as the nutritional qualities. Vacuum evaporators are available in various configurations, such as film and circulation models; they can be single, double, or multi-vessel setups, depending on the required capacity and the method of vapor compression.
To select the right evaporator, it is important to take into account parameters such as the performance of moisture evaporation as well as the steam, electricity and water consumption for cooling, installed power and the equipment dimensions. This will help to determine the most suitable model for your requirements and production conditions. The selection of a vacuum evaporator design relies on numerous factors, such as the product type, desired capacity, and energy efficiency considerations. Falling film vacuum evaporators are often considered one of the best choices for milk and dairy products, as they provide a high degree of concentration with minimal time spent by the product in the temperature-affected zone. This helps to maintain the quality and nutritional properties of the milk.
In addition, mechanical vapor compression (MVR), thermal vapor compression (TVR), and combined systems (MTVR) represent alternative options that may better suit the specific production requirements of the customer. It's also important to note that multi-stage evaporation units - evaporators can be significantly more energy efficient as they operate at lower pressure and temperature conditions. Other factors to consider when selecting the right evaporator include the end product quality, heat recovery, condensate quality, and cleaning time, alongside associated costs such as cleaning, production facility expenses, environmental factors, and overall investment costs.
For small-scale condensed milk production, particularly when working with a limited budget, we recommend utilizing a circulating type vacuum evaporation unit. These units are typically more cost-effective and well-suited for low-volume production, offering efficient evaporation while minimizing any adverse effects on the milk's quality.
Film-type vacuum evaporators use a thin film of milk, which increases the surface area in contact with heat, facilitating faster and more uniform evaporation. This not only reduces processing time but also mitigates the risk of overheating and denaturation of milk proteins. When selecting a specific model, it's crucial to consider parameters such as performance, ease of maintenance, and the availability of spare parts. Additionally, it's important to assess the experience and reputation of the manufacturer. Hybrid vacuum evaporators, which combine features of the film-type and the forced circulation units, are recognized as the most energy-efficient option.
The operating principle of a vacuum evaporation unit with forced circulation for thickening liquid solutions and its features:
- Vacuum evaporation units with forced circulation are designed for concentrating liquid solutions by evaporating the solvent.
- The evaporation process is applied to volatile liquids containing non-volatile or low-volatile substances.
- During the boiling process, the solvent evaporates, resulting in the increased concentration of non-volatile substances.
During the initial stage of processing, vacuum conditions are established within the installation. This is achieved using a specialized pump that removes air and other gases from the working chamber. Creating a vacuum is essential for reducing pressure and accelerating the evaporation of the liquid. The liquid undergoes evaporation to remove it from the product, facilitated by the reduced pressure inside the chamber. At lower pressure, the liquid begins to evaporate at a temperature lower than that required under normal atmospheric pressure conditions. The installation typically features special surfaces on which the liquid evaporates. These surfaces may be heated or have an enlarged area to enhance the evaporation rate. Subsequently, the vapor of the liquid evaporated in the vacuum condenses back into liquid form. This condensation occurs in a separate section of the installation, where conditions are optimized for cooling the vapors and facilitating their transformation into liquid. The condensed liquid is then collected and discharged from the installation.
The remaining gas or steam can be removed from the system using a vacuum pump.
The design of vacuum evaporation units with a forced circulation
The basis of such an installation is a heat exchanger (plate or shell-and-tube, vertical or horizontal type). It ensures effective heat exchange between the liquid and steam. Vacuum evaporation units have an evaporation chamber where the evaporation process takes place. Some equipment models are supplemented with a condenser, inside which the secondary steam is converted back into a liquid state.
Advantages
- Evaporation units with forced circulation have a high rate of evaporation, energy savings and a high quality of the finished product.
- They allow you to preserve the organoleptic properties of the original liquid.
Productivity
These units typically have an average productivity of around 90 kg/hour, with a concentration coefficient reaching up to 65%. Vacuum-forced circulation evaporators serve as the foundational equipment for the industrial concentration of various liquids. For further information or specific model specifications, please don't hesitate to contact us.
To concentrate very viscous products, vacuum evaporation units are equipped with a mixing device.
Vacuum evaporation machines with a mixing device, in addition to the main advantages of vacuum evaporation plants, which include:
- Preservation of nutrients and coloring pigments. Low evaporation temperatures allow for more nutrients and coloring pigments to be retained within the product.
- Possibility of carrying out the process at lower temperatures. This reduces the risk of thermal decomposition of sensitive substances.
- Improved product quality. Thanks to mild processing conditions, the quality of the final product remains high.
There are also additional benefits provided by mixing the product during thermal processing, such as:
- High efficiency when processing large volumes. Vacuum evaporation units are especially effective when working with large volumes of liquid product.
- Increasing the useful temperature difference between the heating agent and the solution, which improves heat transfer.
Vacuum evaporators with a stirrer are especially important for processing thick, highly viscous products. Mixing, especially when the working unit is positioned at an angle utilizing the gravity mixing method, helps to ensure even heat distribution and prevents the product from burning, which can be a problem with high viscosities. In addition, it promotes more efficient evaporation, since stirring improves contact between the product and the steam. This process significantly enhances the quality of the final product while minimizing the risk of defects.
The presence of scrapers on the mixing device significantly improves heat transfer, especially when working with highly viscous products. Scrapers help remove deposits from the heating surface - this ensures more efficient and uniform heating of the product. In addition, the use of pigs reduces the need to frequently stop the plant for cleaning, which increases its productivity and reduces operating costs.
