Description of the dehumidification system
DESSICA DIA systems are modular and adaptable air dehumidification units specially designed to meet the requirements of users in the food processing industry :
- hygienic & solid construction made of AISI 304L or 316L stainless steel sheet, 0.12-inch-thick, smooth and non-sticky inside panel
- made with food contact material (ANIA certificate) for all parts in contact with process air
- easy access with dedicated maintenance doors
These dehumidification systems include the latest innovations for absorption desiccant rotors and use the new energy saving system (Dessica’s patent).
This new feature optimizes the rotation speed of the desiccant rotor in correlation with the evolution of the temperature and humidity conditions of the air to be treated.
DESSICA DIA systems offer a complete solution including filtration, heat exchangers and a control system.
The third generation PPS and PPX silica gel desiccant rotors mounted on our air dryers contains a high active silica gel component.
It provides a high dehumidification performance and reduce energy consumption compared to other silica gel desiccant rotors of the same dimensions.
The DIA boxes are connected to each other by rectangular flanges (0.12-inch folded sheet or 0.20-inch welded) and EPDM seals.
Operating principle of dehumidification systems
DESSICA systems uses two independent and countercurrent air flows through the desiccant rotor, with a slow and continuous pace :
- the main air flow (process air) is dried
- the secondary air flow (reactivation air), of lesser volume, is used to evacuate the moisture retained by the desiccant rotor
Two fans set in motion both air streams.
Silica gel is a high- performance hygroscopic material able to retain the moisture content from ambient air. By floating through the rotor, the humid air loses its moisture captured by the silica gel material.
The dry air is then totally usable. Reactivation air purpose is to evacuate the moisture captured by the silica gel in the rotor. The air is brought to an approximate temperature of 210°F to 320°F (100°C to 160°C) and then crosses the rotor against the wet air flow to remove the moisture retained in the silica gel. The moist reactivation air leaves the dehumidifier to be evacuated outside the building or any other premises.
Benefits of Dessica DIA systems
- Modular and adaptable
- Hygienic and solid construction
- Made with food contact materials
- Easy access with maintenance doors
- Patented Energy Saving System
Applications in the food processing industry
DESSICA DIA systems supplies dry air to feed drying, production processes in packaging or storage environments.
Dairy, food ingredients, meat processing and seafood products are among the many segments where DIA systems provide dry and sterile air.
1) Drying towers, ovens, fluid bed :
Most drying systems operate depending on outdoor climatic conditions : the production capacity is higher in cold weather when the air is dry and it is greatly reduced in hot weather when the absolute humidity of the air is at a high level. For example, a flow rate of 100 tons/h of air introduced into a drying system (for example, an spray drying tower), this represents more than 1 ton/h of additional water introduction or less depending on the time of the year! Besides being responsible for the drop-in production, humidity is also a challenge for the staff to find the right settings to operate the tower to its maximum capacity preventing several days of production disruption due to clogging.
The main benefits of the DESSICA solution are the following :
the production capacity of the drying system is constant and maximized and the residual moisture in the product stabilized throughout the year by air conditions without significant variation in all seasons
clogging and bulking of pulverized products is eliminated
the energy consumption is optimized : dehumidification is an exothermic phenomenon, it increases the temperature from the dry air and therefore reduces the heating of the upstream air in the process. Precooling by condensation can be eliminated or limited to periods of very high humidity by a regulated system giving priority to the dehumidification operation by the desiccant rotor. The energy saving system (DESSICA’s patent) significantly increases the energy efficiency of the system.
The ROI, particularly on a Spray drying tower, is quick for the following reasons :
• increase in production volume over the year
• predictable production volume regardless of climatic conditions
• Easy to adjust operating parameters; reducing staff intervention
• quality of the finished product, which is constant, dryer and therefore more value-added
• less production disruption due to clogging
2) Production environments...
In production, packaging or storage environments, dry air allows :
• prevention of physical (particle) or microbiological contamination
• retention of the original product characteristics
• hygiene, safety and working conditions improvements
• reduction of the post-wash drying process (increase in productivity and absence of post-contamination)
DESSICA DIA system selection
The size of a DIA system depends mainly on the front air velocity towards the various components, therefore the air flow to be treated.
Each component must be selected according to its own selection criteria. Usually, the desiccant rotor, the filtration systems, the cold and hot coils are crucial to define the size of the various casings. The humidity level in the dry air is also a determining factor for choosing the appropriate system size. Thus, the DIA are offered with two thickness dimensions for the desiccant
rotors allowing more flexibility in the sizing. The following quick selection tables are established on the sole criteria of the desiccant rotor.