Highest level of Stem Expansion

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

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.