Falling Film Thin Film Multiple Effect Evaporator Design TVR Multiple Effect Heated Evaporation Plants Evaporator Design

The introduction of Falling film evaporator

Liquor falls down the inside wall of a vertical tube in a thin film that covers the circumference of the entire tube.  High heat transfer coefficients are possible, even with very low delta T.  In the center of the tube is the vapor that has evaporated from the liquor.  The vapor can either flow down the tube with the liquor or up the tube counter flow to the liquor.  After leaving the tube, the vapor flows to a separator to remove liquor drops from the vapor.

Separators are typically centrifugal or impingement using chevrons.  They can be external to the falling film vessel or in some cases they can be integrated with the falling film vessel to save space and reduce installation costs.

Fouling liquors require recirculation.  Even with recirculation, pump power is much lower than forced circulation.  Heat sensitive liquors can be configured for once through operation resulting in a residence time of only a few minutes with very little power consumption for the transfer pumps.

Falling film evaporators work well in zero to low fouling applications and normally can’t be used as crystallizers.  However, they can be combined with forced circulation evaporators so crystallization and fouling liquors can be done in a single evaporator system.

Because low delta T evaporation is possible, falling film works well with MVR and TVR where low delta T operation results in low power and steam operating cost.

Where the maximum liquor temperature is limited due to the material being evaporated or a low grade heat source such as exhaust vapor from dryers or liquefaction vapor, more effects are possible compared to rising film.  

Falling film evaporators are commonly used in the food, pharmaceutical, chemical, pulp & paper, and power industries.

Product Advantages

Owing to the features of high heat transfer coefficient, suitability for small temperature differences high vacuum evaporation, it can widely use waste heat(such as the dryer’s hot air and flue gas), the residual heat(of condensing water, process water and flash steam) to form a waste heat evaporation unit. It completes the task of concentration by reducing or eliminating the use of fresh steam in order to achieve the “ZERO” breakthrough of using the raw steam for evaporation.

The JMZ evaporator is characterized by high efficiency of heat conduction, small temperature difference, no boiling point loss due to liquid level.

Application

Multi effect falling evaporator is widely used in starch and its ramification industry, alcohol industry and chemical industry for evaporation, concentrating and crystallization etc.

Technological Process

Project Cases