Why is it necessary to optimize traditional Hoffmann kilns?
Being first invented in the 19th century, Hoffmann kiln technology is 200 years old and needs to be upgraded. A Hoffmann kiln is energy-extensive, unsustainable, responsible for up to 90% of the factory’s total fuel consumption, too much dependent on the personal experience of the burner, does not produce uniform bricks, and the quality of its products fluctuate.
What is a Hoffmann kiln?
Hoffman Kiln was invented and patented by a German engineer called Friedrich Hoffmann in 1858. The kiln technology brought about a considerable reduction of time and effort and fuel consumption in brick factories, resulting in an improved efficiency at the time. A Hoffmann kiln is basically a main fire passage surrounded on each side by a number of small chambers wherein bricks are placed to be fired the number of chambers depends on the size of the kiln, and can be as many as a hundred. On the rooftop of the main fire passage, there is a fire wagon that holds fire burners and nuzzles. The fire in the Hoffmann kiln burns continuously over the chamber where bricks are kept. Each chamber is fired for a specific time, until the bricks are vitrified properly, and thereafter the fire wagon is rolled to the next room to be fired.
Since older Hoffmann kilns were powered by coal, wood, mazut, or any other locally accessible fuel, they had a long chimney producing a powerful air suction to vacuum the hot air and smoke resulting from the burning process out of the kiln into the air. As a result, traditional Hoffmann kilns were, and still are, among world’s most polluting industries and need to be upgraded and optimized for both economic and environmental reasons.
What are a Hoffmann kiln’s main disadvantages?
Being first invented in the 19th century, Hoffmann kiln technology is 200 years old and needs to be upgraded for economic reasons. Being responsible for up to 90% of a factory’s total fuel consumption, a Hoffmann kiln is energy-intensive and costly to maintain. Moreover, it is too much dependent on the personal experience of the burner, does not produce uniform bricks, and the quality of its products fluctuate.
Since their inventions, some aspects of Hoffmann kilns have been updated in order to enhance their performance, most important of which is the replacement of chimneys with ventilation fans. Other enhancements included giving up coal consumption in favor of mazut or natural gas. However, these solutions either did not render the kiln more cost-effective or environment-friendly, as in the case of ventilation fans. Some other enhancements were not even possible to implement in most parts of the world, as in the case of natural gas. As a result, Hoffmann kilns main disadvantages continue to both harm the environment, and impose high expenses on the industry to this day.
The role of the burner
Hoffmann kilns are not automatic. As a result, the burning process is completely controlled by the burner, that is, the person in charge of the kiln. It is totally up to the burners to adjust the fuel input to the kiln or move the burner wagon to the next chamber. Since the burners do not have any technical means to monitor and control the kiln, they have to completely rely on their intuition. For this reason, the brickmaking cycle is totally dependent to the burner, and cannot be standardized.
A more severe problem in the brickmaking cycle is the nighttime reduction of temperature. Burners have to reduce the fuel input to the kiln during the sleeping hours at night to prevent overheating inside the chambers, a solution that results in longer firing hours, and thus higher costs, more fuel consumption, lower capacity and finally, less efficiency.
Brick quality fluctuates
Full dependency on the burners’ intuition results in fluctuations in the end product. It is common in Hoffmann kilns to see changes in the quality or color of fired bricks, both within the same chamber or among different chambers in the course of time. The problem may get even worse when the old burner quits and a new burner starts to control the kiln. It all happens because the baking process of the Hoffmann kiln has not been scientifically studied and standardized. Fluctuations are bad because they lead to lower customer satisfaction.
For these reasons, Hoffmann kiln is now considered to be inefficient, energy-extensive, wasteful, and unsustainable, imposing all the costs and losses on industry owners. This is why in the 20th century, Hoffmann kilns were abandoned in favor of modern tunnel kilns throughout Europe and North America. Although tunnel kilns are way more environmentally efficient than Hoffmann kilns, they are highly expensive to build and maintain. Therefore, in most developing countries, Hoffmann kilns continue to work as the main means of brick producing in the industrial level. There are even instances where a factory owns a tunnel kiln, but still prefers to use the old Hoffman kiln simply because it is cost-effective. Thus, for economic reasons, tunnel kilns are not a feasible solution to the problems posed by Hoffmann kilns in developing countries.
Basamad Automatic Kiln
Basamad Automatic Kiln (BAK) is an optimized kind of the traditional Hoffmann kiln. It is basically an updated Hoffmann Kiln, equipped with an electronic control system, allowing the operator to instantly monitor the brickmaking process, both on- and off-line. As such, BAK provides the traditional Hoffmann Kiln with the capabilities of a modern tunnel kiln without any changes to the kiln itself. As for the construction and building, BAK operates on the existing Hoffmann Kilns and therefore, does not need any deconstructions or demolitions.
BAK is approved by UNIDO, United Nations Industrial Development Organization, and IFCO, Iran Fuel Conservation Company, a subsidiary of NIOC, National Iranian Oil Company.
BAK is designed and manufactured by Basamad Co., Tehran, Iran. For further information and technical consultation please contact us here.