Although the fire blocking plates and walls in the kiln have many positive effects on the operation and control of the kiln, if they are not set reasonably in terms of quantity and position, they can also have a negative impact on the control. Therefore, several principles are proposed for reference.
1. The function of kiln fire blocking plate and fire blocking wall
The function of the fire blocking plate on the kiln path is basically the same as that of the fire blocking wall. The fire blocking plate is responsible for controlling the upper half of the kiln passage inside the kiln. It is generally made of high-temperature ceramic fiber board and can be adjusted in position outside the kiln roof. The fire barrier is responsible for controlling the lower half of the kiln passage inside the kiln. It is generally constructed with refractory bricks and has a relatively fixed height position. The setting of kiln fire barriers and fire walls is often located at the same cross-sectional position.
1.1 Upper and lower diversion effect
According to the principles of fluid mechanics, due to the influence of geometric pressure head, the hot gas in the kiln always has a tendency to move from bottom to top. In addition, the difference in the horizontal airflow velocity and temperature between the upper and lower channels in the kiln is difficult to avoid due to the difference in the setting of the burner on the firing belt. At this time, the gap between the kiln flame blocking plate and the flame blocking wall can be used to adjust the upward and downward motion distribution of the airflow, in order to balance the heating effect of the product during the firing process.,
1.2 Horizontal diversion effect
Under the action of the main fan at the kiln head, the gas in the high-temperature zone and preheating zone always moves horizontally towards the kiln head in the kiln passage. At this time, the kiln passage is equivalent to a sealed circulation pipeline. The gas near both sides of the kiln wall is affected by frictional forces along the way, and the flow velocity is always lower than that in the middle, especially in the preheating zone, which is a clear laminar state, thus affecting the uniform heating of the product in the horizontal direction. At this point, the horizontal motion distribution of the airflow can be adjusted through the shape of the kiln fire blocking plate and fire blocking wall to balance the heating effect of the product during the firing process.
1.3 Function of Adjusting the Heating Curve
The heating curve of a roller kiln largely depends on the physical and chemical changes that occur during the product firing process, as well as the size and firing cycle of the product, mainly considering the adaptability of the billet to the heating rate. In order to meet the process requirements, kilns generally control the number of burners and fuel combustion in the high temperature zone. In the preheating zone, the main fan at the kiln head is used to extract force, which increases the temperature in the preheating zone.
When adjusting the temperature curve, it is common to see that as the suction force of the kiln's top main fan increases, the temperature in the high-temperature zone decreases, the temperature in the preheating zone increases overall, and the exhaust temperature also increases, but the specified temperature increase in a certain area cannot be achieved. This makes it difficult to achieve the requirements of fast and slow temperature rise in the process of ceramic products, which affects the overall rapid firing. If a fireproof board and fireproof wall are set up in front of the location where the temperature needs to rise sharply, this goal can be achieved.
1.4 River interception effect
As fire blocking plates and walls installed on the kiln passage, they can directly intercept the airflow movement. The fire blocking plates and walls set up for the preheating zone can play an auxiliary role in adjusting the fire blocking plates of the kiln head main fan, smoke main air duct, and smoke branch air duct to a certain extent. The interception effect of the fire blocking plates and walls in the insulation and rapid cooling zones is even more important.
Under normal circumstances, the insulation belt should be in a slightly positive or negative pressure state, while the rapid cooling belt should be in a relatively high positive pressure state. It is normal for a small amount of airflow to still move towards the kiln head at the junction of insulation and rapid cooling. However, in production, due to the fact that this state may not always be achieved when adjusting the balance between the main fan and the exhaust fan, there is often a tendency for the airflow in the insulation belt to move towards the rapid cooling belt. At this time, the kiln Ceramic fire board and fire blocking wall play a key role in ensuring this.