This is a double-layer tunnel drying furnacethat we have installed on-site for a customer in Vietnam. It is used in conjunction with the customer's equipment. The working temperature is 150 degrees Celsius. It has an upper and lower layer conveying method. Materials are conveyed into our baking furnace at the front end and then transferred to the next process after reaching the end. The debugging was very successful.

The following is a brief introduction to the double-layer conveyor tunnel furnace:

I. Structural Features

Double-layer Design

The double-layer conveyor tunnel furnace has two independent conveyor channels on the upper and lower layers. This design effectively utilizes space. Compared with the single-layer tunnel furnace, it can significantly increase the processing capacity of products under the same floor area. For example, in the food processing industry, for baked products like biscuits with relatively small volumes, the upper and lower layers can conduct drying or baking simultaneously, thus improving production efficiency.

Conveyor System

It is equipped with a stable and reliable conveyor device, which is usually composed of conveyor belts or transmission chains. The material of the conveyor belts or chains varies according to the products being processed. For instance, when dealing with high-temperature and heavy ceramic products, heat-resistant metal chains may be used; while in the food industry, food-grade plastic conveyor belts are often adopted to ensure the hygiene and safety of products. The conveying speed can be adjusted according to the actual production requirements, enabling it to flexibly adapt to different production rhythms.

Furnace Body Structure

The furnace body of the tunnel furnace is generally composed of a metal shell and thermal insulation materials. The metal shell plays a role in protection and support, and usually adopts materials like stainless steel, which has good corrosion resistance. The thermal insulation materials can effectively reduce heat loss. For example, thermal insulation materials such as ceramic fiber cotton can gather heat inside the furnace body, improve energy utilization efficiency, and also make the temperature distribution inside the furnace more uniform.

II. Working Principle

Heating Method

The double-layer conveyor tunnel furnace mainly heats through thermal radiation, thermal convection and other means. Inside the furnace body, heating elements such as electric heating wires and gas burners are usually installed. For the electric heating type tunnel furnace, the electric heating wires convert electrical energy into heat energy and transfer the heat to the products on the conveyor belt through thermal radiation and thermal convection. As for the gas-fired tunnel furnace, it generates heat by burning fuels such as natural gas and liquefied gas, and the hot air circulates inside the furnace body to heat the products.

Temperature Control

It is equipped with an advanced temperature control system that can accurately control the temperatures of the upper and lower layers inside the furnace. Temperature sensors monitor the temperature inside the furnace in real time and feed back the signals to the controller. The controller adjusts the power of the heating elements according to the set temperature parameters to keep the temperature inside the furnace within a stable range. For example, in the drying process of electronic components, accurate temperature control is crucial for ensuring the performance and quality of electronic components. The upper and lower layers can be set with different temperatures respectively to meet the drying requirements at different stages.

Heating during Product Conveying

When products are placed on the conveyor belt and enter the tunnel furnace, they will gradually pass through the heating area as the conveyor belt moves. During this process, the products will absorb heat evenly and complete the drying, curing or other heat treatment processes. Due to the double-layer conveyor design, the products on the upper and lower layers can undergo different degrees of heat treatment simultaneously, or the same products can be processed with a time sequence, thereby improving the overall production efficiency.

III. Application Fields

Food Processing Industry

It is widely used in the baking and drying of foods such as bread, biscuits, and nuts. For example, in the production of biscuits, the double-layer conveyor tunnel furnace can first conduct preliminary drying on the lower layer to remove part of the moisture in the dough, and then carry out high-temperature baking on the upper layer to make the surface of the biscuits form a golden color and a crispy texture.

Electronic Industry

It is used for the drying and curing of electronic components. For example, in the production process of circuit boards, it is necessary to dry the circuit boards coated with ink or glue. The double-layer tunnel furnace can set different temperature and time parameters for each layer to effectively remove moisture and make the ink or glue cured, thus improving the quality and stability of the circuit boards.

Building Materials Industry

It is also very suitable for the drying and heat treatment of some small building materials, such as roof tiles and thermal insulation materials. Taking the production of roof tiles as an example, the double-layer tunnel furnace can dry different specifications of roof tiles simultaneously, accelerating the drying process in the production of roof tiles and improving production efficiency.

Chemical Industry

It can be used for the drying and modification treatment of chemical products, such as coatings, pigments, and plastic pellets. For example, in the production of coatings, the drying through the tunnel furnace can remove the solvents in the coatings to form a stable paint film, and the upper and lower layers can simultaneously handle different colors or types of coatings, which is convenient for production management.