Stem Drying & Classification

Tobacco machinery sales

Fluid Bed Dryer

The Garbuio FBD employs vibration to assist fluidisation of the product and convey it through the process. The fluid bed is supported within a chassis which floats on Rosta type flexible supports, and is vibrated by two contra-rotating vibro motors.

Excellent Fill Value for Stem, Cigar Filler and Tea
Air is drawn into the dryer through inlet filters and fans, and is then heated by finned tube steam heat exchangers. This warm air is then passed through perforated stainless steel diffuser plates which carry the fluidised bed of tobacco. Due to the intimate contact between the fluidising air and the tobacco, rapid drying takes place, so that the expansion achieved in the preceding STS process is maintained. The moisture laden air from the fluidised bed passes upwards into a divergent exhaust collection hood, so that any product entrained in the air is able to fall back into the bed. The exhaust is then ducted from the top of the hood to the exhaust cyclones or dust collectors, before being discharged to atmosphere. Depending on capacity, the FBD is divided into two or three separately controlled zones so that air flow and temperature may be independently controlled to optimise the process. Final moisture is controlled by feedback from a moisture meter after the cut stems classifier, by modifying the final zone air temperature set point. Fill value of FBD product is generally superior to that obtained from rotary dryers, due to the relatively rapid drying in the FBD and the absence of rolling and tumbling which curls the product in a rotary dryer.

Steam Treated Stems process (STS)

The Garbuio STS process provides the best possible stem expansion in a simple package unit which can be easily incorporated into an existing process line.

Highest level of Stem Expansion
High moisture cut stem product is introduced at a controlled rate into the STS airlock, where it is contacted by a number of jets of low pressure steam. The free-jet effect results in a high rate of heat and mass transfer between the steam and the product, causing the vapour pressure inside the cellular matrix to increase relative to the surroundings. The steam flow then propels the product through a post-treatment which is in the form of a venturi. The localised pressure reduction which occurs in the venturi throat results in further expansion of the product, which is then discharged onto a take off conveyor. STS product can be dried in rotary or fluid bed dryers. The STS process is basically self-cleaning and suffers no deterioration in performance over several continuous shifts of processing. This is because the steam jets keep the airlock and post treatment tube clean, so the fill value achieved at the end of a day’s production is the same as that achieved when production starts. Clean in place sprays are installed so that at the end of production the machine can be automatically washed down with the minimum of operator intervention. A further advantage of the STS process is that it will perform well even for factory steam supply pressures of 5 or 6 bar, provided this is specified at the time of order placement. Typical steam consumption is only 0.3 kg of steam per 1kg of product. The use of very highly expanded stem can sometimes cause problems in the cigarette due to excessive pressure drop or ‘draw resistance’. The STS is provided with the means to control stem expansion by dilution of the process steam with compressed air, thus reducing and controlling the fill value according to cigarette pressure drop. The STS is simple to maintain and operate, and is fully automatically controlled.

Elutriator

The Garbuio Elutriator is a high efficiency fluidised bed classifier for separating unwanted heavy particles such as knock-outs from dry expanded cut stem. It is also suitable for classification of other granular, free-flowing products such as DIET.

High Efficiency Classification system
The Elutriator employs vibration to assist fluidisation of the product and convey it through the process. The fluid bed is supported within a chassis which floats on coil springs, and is vibrated by two contra-rotating vibro motors. Air is drawn into a plenum chamber through inlet filters by variable speed inlet fan(s). This air then passes through finely perforated stainless steel diffuser plates where it contacts and fluidises the tobacco. The fluidised bed is divided into two zones: the first zone has a relatively low airflow so that only the lightest portion of the product is lifted at this point. This reduces the material load on the subsequent higher airflow zone, so that a greater separation efficiency and selectivity can be achieved. The classification process effectively occurs within the fluid bed. The light material that is ejected upwards from the bed is gathered by a conveying air stream within the converging hood of the machine. The convergent hood design avoids recirculation of material within the hood which would otherwise increase the material loading and reduce overall efficiency. The product is pneumatically conveyed and separated from the air stream by an APS or tangential separator, and the air is exhausted via a dust collector. Automatic controls ensure that the pneumatic conveying air flow is equal to the injection air flow. The degree of classification is simply adjusted by varying the injection fan speed via up/down push button controls located so that the classification performance can be easily observed.

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Fluid Bed Dryer

  • Superior fill value
  • Economical
  • Simple to maintain and operate
  • Suitable for cut expanded stem or cigar filler

Steam Treated Stems process (STS)

  • Superior expansion of cut stem
  • Expansion is maintained throughout long periods of continuous operation
  • Compact, package unit
  • Suitable for use with rotary and fluid bed dryer.
  • Clean in place nozzles incorporated

Elutriator

  • Highly selective classification system for cut stem, DIET etc
  • Minimal heavies present in classified material
  • Simple to control and adjust
  • Suitable for direct coupling to fluid bed dryer discharge