The tunnel kiln technology was developed around mid 19th century in Germany. However, the application of the technology for brick firing took place in the 20th century. Tunnel Kilns is one of the most advanced brick-making technology. A tunnel kiln is a modern industrial furnace widely used in building materials, ceramics, and refractory industries. It is a continuous production of thermal equipment. It is divided into a preheating zone, a firing zone, and a cooling zone according to the length direction of the tunnel kiln.
The Tube Furnace is an electric heating system with a cylindrical tube heated by surrounding heating elements. The types of Tube furnaces, according to the tube’s orientation, include Horizontal Tube Furnaces and Vertical Tube furnaces. A Vertical Tube Furnace is designed for specific heat treatment applications in a vertical position. These batch-processing furnaces feature a vertically arranged quartz tube that heats objects around the tube for processing. The heat treatment applications of the furnace include syntheses and purifications, oxidation, diffusion, and calcination. And thermal annealing of inorganic or organic compounds in labs and industrial sectors.
Key Features of Tunnel Kilns
Tunnel kilns are long structure furnaces primarily used in ceramics manufacturing, particularly brick manufacturing. The solids and gases along the whole kiln zone are considered to be in counterflow heat exchangers. Where solids move counter-currently with the air or gas flow. Great attention has been focused on energy savings in such kilns. Therefore, various mathematical and numerical studies have been conducted on tunnel kilns.
The essential features of Tunnel Kilns are tunnel kilns support energy efficiency by using fiber and silicon carbide (SiC) kiln materials, consistent, high-volume production from units, support fully automated total production plants, high levels of control, give top-quality products, allow mass production of large-size products, and mixed production of multiple product types, computer-controlled to make operation simple and reliable, supports high temperatures up to 1,850°C, low maintenance and minimal downtime, reduced internal air movement for a better firing environment, capable of energy savings through waste heat recovery, etc. One can use various methods to heat tunnel kilns.
Tunnel Kilns Vs. Shuttle kilns
As the name suggests, a shuttle kiln is a car-bottom kiln with a door on either end. The burners are positioned top and bottom on each side, resulting in a turbulent airflow. In terms of design, shuttle kilns can either be updraft or downdraft. The several applications of Shuttle kilns include Heavy clay, porcelain, sanitary ware, earthenware, stoneware, and refractory material, using temperatures up to 1800ºC. A tunnel kiln on the other hand is a long structure where only the central portion is directly heated.
A tunnel kiln is a continuously moving ware kiln in which the clay products to be fired are passed on cars through a long horizontal tunnel. The firing of products occurs at the central part of the tunnel. The main benefits of tunnel kiln technology lie in its ability to fire various clay products better.
Reasons to use a Vertical Tube Furnace
The Vertical Tube Furnace adopts a structured design with a vertically placed furnace tube and heating wire distributed in a ring shape. One can operate the equipment under atmosphere and vacuum conditions and be used as an ordinary tube furnace, suitable for university laboratories and scientific research institutes.
The essential features and benefits of a Vertical Tube Furnace include High purity alumina inorganic refractory, overall vacuum molding chamber, energy saving and ensure uniformity of temperature zone and a fast heating rate, low power consumable, exquisite structure, and lightweight; it is the ideal furnace for material research labs, also used in the factory for small production, it is available in 1100°C 1400°C and 1600°C temperature, single and three zones as required has a Quartz or high purity alumina tube, a Programmable Temperature Controller, excellent temperature uniformity, rugged and durable construction, etc.
