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Tobacco Curer

Curing is the process used to achieve the texture, colour and overall quality of a specific tobacco type. It take place in three steps: yellowing to obtain the desired colour at low temperature, leaf drying with fairly high heat and rapid air circulation and killing the stem with high heat and little air movement. It usually involves a heat source that reduces chlorophyll content and converts leaf starch into sugar, while the tobacco changes colour from green to brown, closer to the colour and texture you will find in a typical cigarette.
While some tobacco is normally air-cured or sun-cured, most commonly, the heat is introduced into a curing barn or shed through pipes from an exterior furnace. This is known as flue-curing.
The curing process for flue-cured tobacco production is by far the greatest energy user (constitutes more than 80% of total energy requirements).

Curing tobacco leaves has traditionally involved the consumption of large quantities of wood fuel however in recent years, alternative methods and fuels have also been introduced in several countries. These fuels include gas, coal, fuel oil and liquid petroleum gas (LPG).  

LPG has become the primary fuel used in this process, replacing wood and accounting for almost 70% of production. Almost all bulk-curing barns built since the early 1970s are equipped with LPG gas burners. It lights instantly, is easily controlled, and is a constant and uniform source of heat.

Combustion gases have been found to produce tobacco-specific nitrosamines, which are deemed to be carcinogenic. Producers are now required to retrofit, or change all flue-curing barns to operate only with indirect-fired curing systems. In these systems, direct mixing of flue gases with curing combustion gases is prevented by passing combustion gases through heat exchangers or by allowing combustion to take place outside of the barn with the resulting heat being conducted into the barn via hot water or steam.

Since some heat loss is unavoidable with indirect curing systems, it is very important for growers to gain as much heating system efficiency as possible in order to control fuel costs. The single greatest reason for burner inefficiency is improper ventilation. Growers have switched from fuel oil to LPG because LPG systems are more efficient – LPG and air mix better during combustion than fuel oil and air. This allows for a lower excess air setting on the gas burner and improves the efficiency of the system. On average, a well-maintained and operated barn will cure approximately 9 pounds of leaf per gallon of LPG.

Features

  • Tobacco drying that respects the environment
  • Easy operation
  • Economical in operation

Benefits

LPG curers allows for a lower excess air setting on the gas burner which helps to improve the efficiency of the system. 

With LPG curers' better temperature control system and uniform heat distribution than other energy source can be achieved and  fewer leaves are exposed in risk or damaged during curing .

LPG could be burnt directly in the barn, thus avoiding heat loss through the chimney as in a normal flue piped system,less contaminants are introduced with the combustion gases and it is claimed that LPG tobacco curing leaf quality is, in fact, superior to that of other fuel dried. Combustion gases from other fuels could contaminate tobacco leafs by depositing soot and aromatic materials, sulphur compounds particularly if there is any malfunction of the burner or controls.

LPG system advantages are the good fuel utilization ,a high degree of flexibility and low first cost of the curing equipment.

LPG curers are environment friendly compared to traditional curers that rely on biomass as a fuel source.

A high calorific value (13,9KWH ou 12th/Kg).

It reduces frequent equipment maintenance and cleaning.