Rising Film Evaporation

Evaporators are used in process engineering and food technology for increasing the concentration of solutions. The allows the operating behaviour of a rising film evaporator to be investigated. The untreated solution is fed from the feed tank below into the evaporator. The evaporator is a double pipe heat exchanger that is heated by steam. The steam pressure on the casing side is adjusted with a PID controller. A cyclone is installed after the evaporator to separate the evaporated solvent and the concentrated solution. The solvent vapour removed is condensed in a water-cooled condenser and collected in a tank. The concentrated solution can also be collected in a tank or fed back into the evaporator for the concentration to be increased further. Part of the solvent is removed by evaporation, which means that the solution retains a higher concentration of dissolved solids. Film evaporators are used in particular for temperature-sensitive solutions such as milk.

To clean the system while installed, a pump and cleaning nozzles are fitted in the condensate and concentrate tanks.

Common salt and water are the recommended materials for experiments.

The two tanks, the cyclone and the condenser are made of glass for better observation. The system can also be operated under a vacuum to reduce the boiling point of the solvent. All relevant pressures, temperatures and flow rates are measured to allow evaluation and monitoring of the process.

Specification:

Water jet pump and vacuum controller to reduce the evaporation temperature

Separation of concentrated solution and evaporated solvent using glass cyclone

Glass tanks for concentrate and condensate

Measurement of flow rate, pressure and temperature

Steam supply from laboratory network

Glass condenser for condensation of removed solvent vapour

Stainless steel feed tank

Rising film evaporator for increasing the concentration of temperature-sensitive solutions

Stainless steel steam-heated single pipe evaporator

Control valve for adjustment of steam pressure via PID controller.

Technical data

Rising film evaporator

Heat transfer surface: approx. 0,08m2

Length: approx. 1,2m

Control valve: Kvs value: 0,4m3/h

Tanks

Feed: approx. 30L

Concentrate, condensate: approx. 10L each

Water jet pump

Final vacuum: approx. 100mbar

Flow rate: approx. 90L/min

Vacuum controller: -100…0kPa

Condenser for solvent vapour

Heat transfer surface: approx. 0,2m2

Measuring ranges

Flow rate: 2…36L/h; 0…1000L/h

Temperature: 7x 0…170°C

Pressure: -1…1bar; 0…6bar (abs); 0…10bar

230V, 50Hz, 1 phase

230V, 60Hz, 1 phase

120V, 60Hz, 1 phase

Dimensions and weight

LxWxH: 1420x750x2640mm

Weight: approx. 300kg.