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Carel Industries humiFog units for multizone (left) and single zone (right) duct applications. Credit: Carel Industries S.p.A.
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Carel Industries’ Daniel Chen, marketing manager for HVAC in the APAC region.
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A Smart Fog ES100 humidifier in action.
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humiFog unit for direct room applications
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A Smart Fog ES100 humidifier installed at a storage facility.
Tobacco needs to be stored at a quite narrow relative humidity range to retain its quality. Tobacco Asia talked to two suppliers of humidification systems.
Tobacco is a rather delicate (even fickle) commodity that requires appropriate handling and needs to be stored at the right air conditions if it is to retain its quality and aroma. Being naturally hygroscopic, it attracts moisture from its environment. When relative air humidity (rh) gets too high, mold and mildew can easily grow and a dank odor develops as the leaves begin to decompose rapidly. Insect pests also may settle in when tobacco bales are too moist. Yet if the air’s rh value becomes too low, the commodity gives off its inherent moisture content. It then dries out quickly, causing it to become brittle, developing cracks and tears, losing water weight, color, and aroma.
It is therefore crucially important to keep tobacco not only well ventilated, but to also store it under the right air temperature and humidity. As the commodity is grown, processed, and stored around the world and in vastly different climate
zones from tropical and subtropical to temperate, maintaining the optimal conditions can pose a challenge. The installation of humidity control systems in warehouses and storage rooms helps to protect the precious product from losing its value and usability. While not coming dirt cheap, such systems are a wise and sensible investment. They are a great option for commercially storing finished end products as well.
Carel Industries S.p.A.
Following its founding in 1973, Italian firm Carel Industries S.p.A. provided air conditioning and humidification solutions to numerous industries worldwide. In 2011, Carel also turned its attention to the lucrative tobacco industry sector, offering custom-tailored systems for all production stages, from processing to storage. “During the various stages of tobacco processing, the air needs to be
kept at between 20°C and 24°C, with 60%-70% relative humidity (rh),” explained Daniel Chen, marketing manager for heating, ventilation, and air conditioning systems (HVAC) in the Asia-Pacific region. However, in post-processing storage, the air temperature should hover at a rather constant 20°C, with relative humidity of 70%-75%, he said.
Depending on the storage facility’s geographical location and surrounding climatic conditions, an individual approach to humidification is imperative. There is no “one size fits all” solution, according to Chen. “During the design stage we need to take into account the local climate and weather which affect the level of humidity in the warehouse,” he said. “We’d recommend different products for different climatic regions in order to ensure adequate tobacco moisture in the local context.”
For that purpose, Carel manufactures a range of humidifiers that can be adapted to varying environments as well as the specific requirements of the tobacco industry. These comprise the high-pressure “atomized water” humidifier, humiFog; the ducted steam distributor, ultimateSAM; the ultrasonic humidification system, humiSonic; the compressed air-and-water atomizer, MC; and, lastly, the centrifugal humidifier, humiDisk. All of these solutions were developed by Carel Industries.
As a so-called “atomizing adiabetic humidifier”, humiFog disperses “demineralized water into micron-sized, airborne droplets,” Chen explained. This, he said, not only ensures a high absorption rate and naturally lowers the air temperature, but it also reduces the energy requirement of the cooling system.
The ultimateSAM system utilizes normal atmospheric pressure. Its special aircushion thermal insulation reduces heat transfer to the air within the duct, thereby minimizing losses through condensation.
As its name suggests, HumiSonic deploys ultrasonic technology to humidify air. The microscopic water droplets that are produced measure just around 1 micron in diameter, which ensures high absorption efficiency. Just like humiFog, Carel’s MC system likewise is categorized as an “atomizing adiabatic humidifier”, using the energy from compressed air to atomize water into micrometric droplets.
Relying on centrifugal force, HumiDisk deploys a rotating disk in order to disperse water into millions of tiny droplets. Subsequently released by an integrated fan, they are humidifying and cool the air.
However, what when the rh value proves to be excessively high, i.e. the air is too moist and would require de-humidification? “There are several ways to dehumidify, including refrigeration-based dehumidification,” said Chen. “Should a tobacco plant opt for the installation of an air handling unit [AHU] for overall temperature and humidity control, Carel Industries can provide control solutions for the entire AHU in addition to a customized humidification system.”
Chen added that although humidification and dehumidification rely on different technical principles, both functionalities could nevertheless be integrated within a single system. “For example, in the AHU, humidification or dehumidification can be achieved by different sections [of the integrated system] and regulated according to the actual ambient air condition and the indoor air condition required.”
An example for multizone deployment
To illustrate that Carel’s systems can be deployed for humidity control in a multizone setting (e.g. a warehouse comprising several separate storage rooms), Chen provided a fictional case study:
“Let’s take as an example the humiFog multizone configuration that we offer for applications in which a pumping unit is used to supply pressurized water to up to six different [storage area] zones. The master unit controls one principal zone based on sensor readings or an external control signal, managing the distribution and atomization system to maintain the correct humidity and/or temperature level in that specific zone. All the other sub zones [within the grid] have individual controller units installed, each of which continuously communicates with the master unit and – again based on localized sensor readings or an external control signal – manages the distribution and atomization system in the respective sub zones completely independently. The multizone configuration rationalizes the use of the humiFog pumping unit since it can manage multiple zones at the same time without the need to install a pumping unit for each AHU.”
Apart from actual tobacco storage, Carel Industries also offers air conditioning and humidification solutions for other tobacco industry purposes, for instance the various stages of leaf processing.
Smart Fog Manufacturing Inc.
Headquartered in Reno in the arid desert state of Nevada, it seems rather ironic that US outfit Smart Fog Manufacturing Inc. would engage itself with humidification. Yet, the company has developed proprietary systems that are utilized by a large number of commercial sectors, including the food and wine industries, pharmaceuticals, clean room operations, and even aeronautics. In 1996, the firm also moved into tobacco with two custom-developed humidification systems.
As far as tobacco is concerned, “Smart Fog specializes in non-wetting humidification, which is crucial to tobacco storage for maintaining quality and preventing [product] loss,” the company’s sales manager, Miriam Gold, told Tobacco Asia. She said that a constant rh level of 70% is typically recommended for tobacco. ”If the rh percentage is lower, the tobacco leaves will dry out and cannot be used.” If it gets too high, “mold and other diseases can grow and damage the product, reducing its quality.”
According to Gold, the proprietary Smart Fog systems, which are available in two models, are used in many mission-critical applications and can operate in extreme air temperature conditions ranging from -20°C to 80°C. “Our systems really fit any environment and do not require any calibration to maintain the relative humidity in any situation,” she asserted.
Smart Fog’s patented technology is based on a natural decorrelation process caused by the negative charge of the oxygen molecule and the positive charge of the hydrogen molecule – the two substances that make up water, or H2O – attracting one another. “Our technology provides 100% evaporation of the [water] droplets into the air. The droplets from our system never touch any surface, hence it’s called ‘non-wetting’. Each droplet introduced by the system into the air is calculated and evenly distributed throughout the space without causing high humidity pockets,” Gold elaborated. Smart Fog systems work either as a standalone or, alternatively, together with any existing HVAC system.
A Smart Fog set-up includes an intelligent industrial-grade PLC controller unit that utilizes the company’s proprietary “smart algorithms”, as well as an rh sensor. Communicating with the sensor, the PLC controller operates one or several humidifier units according to the set-point defined by the user.
“Our intelligent algorithms know how and when the humidifier must spring into action in order to maintain the target rh percentage required without causing any humidity fluctuations,” elaborated Gold. The controller also imparts safety features that can reliably forecast errors such as impending rh value breakouts. “The system will never overshoot the required humidity level,” assured Gold.
Smart Fog systems are modular, meaning that depending on the storage facility size humidifier units can be added as needed to ensure that the entire space is covered. Regardless of how many humidifier units are deployed, they are all managed by a single controller unit.
However, it may be required to install several humidity sensors to ensure correct humidity readings throughout the entire storage facility. “We also offer multizone control options that can independently monitor and operate humidifiers in multiple rooms within the same facility,” added Gold. “Whether it’s one smaller storage room or an entire warehouse, we design and engineer each project to the highest possible efficiency.”
Misting Tobacco: Not a Good Idea
Tobacco merchants, processors, and manufacturers in some less developed countries sometimes resort to water-spraying or misting their stored product in an attempt to keep it at the correct moisture level. Both our respondents opined that this was an ill-guided idea that easily could do more harm than good.
“In general, spraying water on tobacco is not a smart solution, because the humidity [seeping into the product] will be almost impossible to control,” said Carel Industries’ Daniel Chen. “Furthermore, it will be difficult to keep the air humidity within a constant range and this will invariably impact negatively on the tobacco quality.”
While Smart Fog’s Miriam Gold said that water-spraying can “temporarily create humidity”, it was nevertheless impossible to control it accurately, leading to wild humidity fluctuations that damage the product. “Also, water misting will never achieve the required relative humidity. In the best case not more than 50%, which is too dry for tobacco storage,” she pointed out.
Simply decking out a storage facility with air conditioning units was not a solution either, both respondents concurred. Although it could help keep the air temperature within the right range, the humidity in the air would merely be “churned around” rather than being controlled and adjusted as needed.