Dehumidifying Air So Candy's Just Right
October 1, 2010
Candy and confectionery manufacturers pay careful attention to the moisture level of their production area environment. When they don’t, the sweet product can be too soft, too hard or stick together.
Liquid desiccant dehumidification systems deliver precise, energy efficient temperature and humidity control for candy and confectionery manufacturing, packaging and storage. The technology can provide improved product quality, increased sanitation and prolonged product shelf life.
The dehumidification system works by utilizing a continuous volume of liquid desiccant solution sprayed over an evaporator coil or contact-surface packing to cool, remove moisture and sanitize the air. A fan induces the air to be conditioned across the coil or contact surface and into the process space. Due to the nature of the liquid, the coil never freezes and defrost cycles are not required. This allows leaving-air conditions to remain constant.
Kathabar Dehumidification Systems Inc., Somerset, N.J., provided three candy industry customers with different requirements with three unique solutions using liquid desiccant dehumidification.
Candy Plant No. 1Candy Plant No. 1 needed conditioned air supplied to the forming and wrapping areas of the plant. Kathabar created a system with separate units for each area and connected them with a single regenerator. Due to pressurization and exhaust requirements, the forming area’s cooling system used 100 percent outside air precooled with a cooling coil to remove the "easy" water from the air. A Kathabar model 1200FV unit reduced the air to 50°F (10°C) and 20 percent relative humidity (RH). This air, plus supplemental recirculated-air cooling units, then held the space at 60°F (15.6°C) and 35 percent RH. The Kathabar system used 46 tons of 35°F (1.67°C) propylene glycol as a coolant (figure 1).
The wrapping area (figure 2) had a separate Kathabar air system handling 20 percent outside air and 80 percent return air. Again, the coolant was 35°F (1.67°C) propylene glycol. The Kathabar dehumidifier delivered 57°F (13.9°C), 20 percent RH air to the space, where again, supplemental cooling with air handling controlled it at 70°F (23.9°C) and 35 percent RH.
The common model 6FP regenerator for the two units required a maximum of 145 lb/hr of 15 psig low-pressure steam. A solution interchange was used in the system to further reduce the already low energy requirements.
Using a common regenerator reduced the system’s first cost, saved floor space, and required only one regenerator air inlet (figure 3). The single regenerator used less heat energy and reduced steam and condensate piping as well as the amount of ductwork, penetrations and controls.
Numerous conditioners can work with a common regenerator. In this case, two conditioners and a regenerator comprised the dehumidification system.
Candy Plant No. 2Candy Plant No. 2 needed flexibility. The manufacturer wanted to combine systems and separate the conditioner from the regenerator with either vertical or horizontal distance. In this combined panning and packaging system, Kathabar mixed outside air and return air from the packaging area. The system delivered 55°F (12.8°C) and 20 percent RH air to the packaging room where ceiling-hung recirculated-air cooling units handled the sensible loads. For two pans, the system used 1,500 cfm directly off the Kathabar units. This air, plus pressurization air from the packaging room, was made up of outside air.
The model 800FV conditioner was sized to handle a wash-down load for the packaging room. During normal operations, the unit removed 255 lb/hr of water from the air. However, after a wash-down cycle, the unit removed 355 lb/hr of water and dried the space completely in two hours.
The model 6FP regenerator was located in a boiler room 50 feet from the model 800FV conditioner location with small piping connecting the two units.
Candy Plant No. 3Candy Plant No. 3 needed climate control for storage in a multi-level warehouse at 60°F (15.6°C) and 35 percent RH. Sensible or temperature control was handled by return-air handling units on each floor that cooled the air only to the temperature required to maintain 60°F (15.6°C). The single Kathabar unit then fed 53°F (11.7°C), 15 percent RH air to each floor and maintained the proper 35 percent RH.
The 17,500 scfm unit used 40 tons of 28°F (-2.22°C) propylene glycol as a coolant, but chilled water at 42°F (5.56°C) also could have been used. The regenerator was a model 3FP, which requires 950 scfm for regeneration – a mere 5.55 percent of the total dehumidification air volume. This low regeneration air volume reduces energy requirements, minimizes equipment room space, and lowers utilities. Only 448 lb/hr of 15 psig steam was needed for the regenerator.
Moisture levels are of utmost importance to candy and confectionery production, efficiency and quality. Kathabar’s liquid desiccant dehumidification systems provided consistent temperature and humidity conditions necessary for the differing needs of the three candy applications.
For more information, go to www.kathabar.com.