Product case history: humidity and gelatine
A scraped heat surface heat exchanger extrudes lacerated gelatine “noodles” from a gelatinous liquid, creating the greatest possible surface exposure for drying. An oscillating belt then distributes the “noodles” onto the dryer conveyor.
Just entering the gelatine market, a major chemical company in India approached Kathabar Inc. for its equipment needs. Based upon the desired production rate, the company sized and supplied a continuous gelatine dryer system and recommended a 29,000-cfm dehumidification system to be used in conjunction with the dryer.
The dehumidification equipment, positioned adjacent to the gelatine dryer, removes moisture from the air to allow for high drying efficiency. In the first zone of the dryer, 20% rh air is needed so moisture can be extracted from the gelatine by vapor pressure differential.
In subsequent dryer zones, higher temperature and humidity air completes the gelatine drying to the desired moisture content.
The air inside the dryer is moved through the gelatine bed by low horsepower fans. In each dryer zone, heating coils are used as the air is directed upward and downward through the sequential zones of the dryer.
Conveyor speed and drying temperatures vary with the gelatine concentrations and extractions. At the discharge end, the product is broken up by a rough grinder in preparation for further processing and storage.
Climate controlComplicating the process further was India’s climate, where they experience a monsoon (wet) season.
With the gelatine dryer process requiring 100% outside air, a liquid desiccant dehumidification system — capable of removing up to 150 grains of moisture from the air — was necessary to supply 20% rh, even at monsoon conditions.
During continuous, 24-hour operation of the system, 52,800 lb of water are removed each day. In effect, the system “weatherproofs” the dryer, allowing for a more consistent end product — regardless of outside weather conditions.
Another benefit of pairing the dehumidifier with continuous dryers was energy savings for the customer. Supplying dehumidified air to the dryer allows for use of waste heat from the dryer.
Adding to the savings is the use of cooling tower water as a coolant and low-pressure steam for regeneration. In this application, the system eliminates 3,980,250 Btuh or 332 ton of air conditioning refrigeration and 1,472,040 Btuh of reheat energy.
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