Improvement introduced in a greenhouse for drying tobacco leaves.

Description

/ 6 Improvement introduced in a greenhouse for drying tobacco leaves. [1] The present utility model patent application follows, for an electric drying oven for tobacco leaves, which is constructed to precisely control temperature and ventilation during the curing process, replacing the direct fire of firewood with electric resistors. Its basic structure consists of a drying chamber, usually made of thermally insulated masonry, where the leaves are hung on rods or supports, allowing uniform circulation of hot air. The electric heating source, formed by resistors, converts electrical energy into heat, gradually raising the temperature according to the drying stage. A ventilation system, with fans and air ducts, distributes the heat homogeneously within the chamber, avoiding cold spots and ensuring that all leaves receive the same level of heat.This application also includes a control panel that operates the greenhouse, responsible for regulating temperature, time, and ventilation through thermostats, sensors, and automatic controllers, allowing for precise adjustment of each phase of the process. There are also adjustable exhaust ducts or vents, whose function is to eliminate moisture released by the leaves and renew the internal air, maintaining a balance between heat and ventilation. [2] Together, these components allow the electric drying barn to operate in a clean, efficient and controlled manner, providing uniform drying, with less risk of burning the leaves and greater standardization of the final quality of the tobacco. STATE OF THE ART: [3] As is known from the state of the art, wood-fired kilns used for drying tobacco leaves, also known as curing kilns, are structures intended for Petition 870250099276, dated 10 / 30 / 2025, p. 7 / 32 / 6 gradual removal of moisture from freshly harvested leaves, in a controlled manner, with the aim of preserving color, aroma and texture, guaranteeing the commercial quality of the tobacco. In general, they are constructed of masonry, metal or wood and consist of a drying chamber at the top, where the leaves are hung on rods, and a furnace at the bottom, where the firewood is burned. The heat generated is conducted through ducts or coils to the drying chamber, while adjustable chimneys and openings allow control of ventilation and internal temperature. The process begins with the loading of the leaves, which are tied and hung inside the drying shed. In the initial phase, called yellowing, the temperature is maintained between 35 °C and 40 °C, promoting the partial loss of moisture and the change in color of the leaves from green to yellow.Next, during the leaf drying phase, the temperature is gradually raised to approximately 45°C to 55°C, fixing the colors and removing surface moisture. Subsequently, the veins are dried when the temperature reaches 60°C to 70°C, eliminating residual moisture until the leaves become firm and brittle. Once the process is complete, the oven is slowly cooled and the leaves are removed to rest in a dry, well-ventilated place before sorting. [4] Temperature and ventilation control is performed manually by the operator, who regulates the intensity of the wood burning and the air inlet and outlet openings. In more modern versions, sensors and thermostats automate this control, ensuring greater precision and fuel economy. The firewood must be dry and burn evenly, such as eucalyptus or angico, to ensure constant heat and thermal efficiency, which also depends on good insulation of the structure and correct sizing of the hot air circulation ducts. Petition 870250099276, dated 10 / 30 / 2025, page 8 / 32 / 6 [5] As an example, we can cite the document “MU 7603334-1” entitled TOBACCO LEAF CURING AND DRYING OVEN, which comprises an oven for curing and drying tobacco leaves, which due to its large production and dimensions is aimed at producers with large tobacco production areas. The great advantage of this system in relation to the traditional system is that the yellowing phase is carried out by taking advantage of the excess moisture and heat of the tobacco that is being dried in the leaf drying chamber.The curing and drying barn for leaf tobacco comprises a wood-fired oven located in the heat storage chamber, exhaust piping for gases, a ventilation system for forced convection, an air intake nozzle, a return duct for air from the adjacent chamber, openings located in the upper part of the storage chamber that conduct heat to the tobacco leaf drying chamber, a cart containing the tobacco leaves, lateral ducts below the drying chamber that carry heat to the yellowing chamber, and parallel tunnels that conduct excess heat and moisture to the yellowing chamber. [6] It turns out that, although wood-fired greenhouses have advantages such as relatively low installation cost, high drying capacity and simple maintenance, they also require constant monitoring during operation, consume a large amount of firewood when poorly designed, generating considerable environmental impact, and can cause overheating and damage to the leaves if operated without experience. [7] Another factor of considerable importance occurs in the conduction of heated air, which in many cases encounters sharp corners along the structural path, causing resistance to flow and, consequently, compromising the fluidity of the heated air. OBJECTIVE OF THE PATENT; Petition 870250099276, dated 10 / 30 / 2025, page 9 / 32 / 6 [8] In order to solve these problems, the inventor developed an electric drying oven for tobacco leaves, designed to precisely control temperature and ventilation during the curing process, replacing wood fire with electric resistors. The oven consists of a thermally insulated drying chamber where the leaves are hung; an electric heating source with resistors that generate heat gradually; a ventilation system with fans and ducts that distribute hot air evenly; and a control panel equipped with sensors and thermostats that regulate temperature, time and ventilation. It also includes exhaust ducts to eliminate moisture and renew the internal air. The combination of these elements provides uniform drying, clean and efficient operation, reducing the risk of burning and ensuring higher quality tobacco. [9] Explained superficially, the present application can be better understood according to the attached drawings, which show: Figure 1 - Schematic side view of the greenhouse; Figure 2 - Opposite side schematic view, according to the previous figure; Figure 3 - Schematic view showing the interior of the greenhouse, highlighting the chamber, the wooden grating, the exhaust fans arranged on the dividing wall of the flow chamber, the set of openings, the electrical resistors, the mechanical fins, the conduction ramp and the lower fins; Figure 4 - Schematic top plan view, according to the previous figure.

[10] In accordance with the attached drawings, the present utility model patent application follows for an “IMPROVEMENT INTRODUCED IN A DRYING OVEN FOR TOBACCO LEAVES”, wherein the oven (1) is Petition 870250099276, dated 10 / 30 / 2025, page 10 / 32 / 6 consisting of a chamber (2) enclosed by a roof (3), equipped at its rear end (4) and on the sides (5) with a series of lower fins (6).

[11] Internally, the chamber (2) has a partition wall (7) provided with a set of openings (8) arranged linearly and parallel to the floor (9). Above the said partition wall (7), there is a pair of exhaust fans (10) facing the interior of a flow chamber (11), which contains a set of electrical resistors (12) arranged just above a conduction ramp (13).

[12] The resistors (12) are kept under tension between the partition wall (7) and a closing wall (14), the latter being equipped with mechanical fins (15) in its upper portion.

[13] The chamber (2) is completed by a main door (16), intended for access to the interior of the chamber, and by a maintenance door (17), located in the flow chamber (11). At strategic points, the chamber (2) also has a control center (18), located externally and communicating with humidity and temperature sensors (not shown), as well as with mechanical vanes (15), in order to allow automatic control of the internal conditions of the drying process. [ 14] The chamber (2) also comprises a set of wooden grating ( 1 9 ), intended for the accommodation of tobacco leaves during the curing process, and is covered at the top by a roof (20), which protects the whole and contributes to the thermal insulation of the structure. [ 1 5] Thus constituted, the greenhouse ( 1 ) is intended for the drying process of tobacco leaves. In this way, by means of the pre-setting of the sensors (not shown) in the control unit (18), the exhaust fans (10) are activated so that the air contained in the Petition 870250099276, dated 10 / 30 / 2025, page 11 / 32 / 6 interior of chamber (2) be projected into the interior of flow chamber (11).

[16] In this condition, the air is forced to pass through the electrical resistances (12), promoting heat exchange by which it is heated. Through the conduction ramp (13), the heated air is directed, without any obstruction, into the interior of the chamber (2), through the set of openings (8) arranged parallel to the floor (9).

[17] The heated air, upon entering chamber (2), establishes an internal circular flow, promoting the gradual and controlled heating of the environment, according to the temperature and humidity parameters monitored by the sensors (not shown).

[18] During the process, some of the humid air, being denser, naturally tends to flow through the lower fins (6). However, given the need to intensify the removal of internal humidity, the control unit (18) automatically activates the mechanical fins (15), forcing out the saturated air and allowing the continuous renewal of the dry air flow. [ 1 9] In this way, the system provides precise and automated control of drying conditions, ensuring that the tobacco leaves placed on the wooden crates ( 1 9) are subjected to a uniform, efficient and high quality process. Petition 870250099276, dated 10 / 30 / 2025, page 12 / 32

Claims

CLAIM: 1 - “IMPROVEMENT INTRODUCED IN A TOBACCO LEAF DRYING OVEN”, characterized by comprising an oven (1) formed by a main chamber (2) closed by a roof (3), equipped at its rear end (4) and sides (5) with lower fins (6), for partial drainage of humid air from the interior, causing renewal of the airflow; inside which there is a partition wall (7) equipped with a set of openings (8) arranged linearly and parallel to the floor (9), responsible for the controlled passage of heated air uniformly inside the chamber; above the partition wall (7) there is a pair of exhaust fans (10) directed towards the interior of a flow chamber (11) promoting the forced circulation of air, from the main chamber to the flow chamber, while the said flow chamber (11) contains a set of electrical resistances (12) arranged above a conduction ramp (1 3) which directs the heated flow back to chamber (2);The resistors (12) are positioned between the partition wall (7) and a closing wall (14), the latter being equipped with mechanical fins (15) for regulating the saturated air outlet located in the upper portion of said closing wall (14), while the chamber (2) is completed by an access door (16), and by a maintenance door (17) located in the flow chamber (11); at strategic points, the chamber (2) also has a control unit (18) located externally and communicating with humidity and temperature sensors, as well as with the mechanical fins (15), allowing automatic and precise control of the internal drying conditions; the chamber (2) also includes a wooden grid (19) for accommodating tobacco leaves during the curing process, being covered at the top by a roof (20). Petition 870250099276, dated 10 / 30 / 2025, page 13 / 32

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