Eight Key Precautions When Igniting The Tunnel Kiln Again

For the tunnel kiln, due to its construction, most of the internal use of refractory masonry, kiln out of service for a period of time to re-open the kiln, the kiln should be re-adjusted on the various systems and settings, and according to the performance of the refractory material for the kiln for the heating process, and gradually make the kiln temperature to the normal use of temperature. When again ignition of the kiln check when again on the tunnel kiln ignition operation, the kiln should be a variety of systems and equipment, a variety of facilities for detailed inspection, to provide sufficient conditions for ignition. The following are the specific issues to be noted:

Tunnel kiln bottom cooling system is specially designed for tunnel kiln track and kiln car system, it can reduce the temperature under the kiln car, try to make the kiln car track thermal expansion length control in the minimum range, and the kiln car cooling, so that the kiln car heat deformation at the minimum value. When checking the cooling system at the bottom of the kiln, the key problem to be solved is to ensure that the cooling air supply equipment at the bottom of the kiln is in normal working condition, so that the bottom ventilation pipe is unobstructed, and the air volume of the pipeline for extracting residual hot air is enough to pump out all the cooling air.

The main function of the kiln car operation system is to ensure that the kiln car is not only running normally in the kiln, but also requires that the operation system outside the kiln can realize the normal operation of the entire production line, so that the unloading part of the brick can be unloaded in a timely manner to the end of the brick billets, empty kiln cars can be quickly sent to the billet yard, the billet yarded kiln car can be sent to the drying room or tunnel kiln at the necessary time. When checking the kiln car operation system, special attention should be paid to the working condition of the kiln car jacking machine to ensure that the car jacking machine can be in accordance with the predetermined speed, the exact location of the kiln car to the kiln at the designated location. For the pulling machine, to make it in the specified time to pull the kiln car out of the tunnel kiln on top of the electric pallet. The electric pallets at both ends of the kiln should be able to enable the fired brick cars on the return line or inside the kiln to enter or leave the kiln in a timely manner. The running equipment on the return line can not only transport the fired brick car to the unloading place, but also transport the empty car to the billet yard, and send the billet yarded kiln car to the incoming electric pallet.

Ventilation system of the kiln firing operation has a very important significance, the kiln temperature and temperature uniformity depends on the ventilation capacity and air distribution of good and bad, the firing process is the process of energy exchange process, moisture and heat exchange process, these are by adjusting the kiln on the ventilation system of the air volume to achieve. Inspection should focus on whether the management channel is smooth, should be cleaned up the accumulated dust in the pipe. Various control valve action is flexible, can be adjusted to the required position, whether it can achieve the purpose of controlling the amount of air supply and exhaust. Whether the insulation on the pipeline insulation effect is good, because it is related to the waste heat wind temperature to meet the drying requirements, the temperature of the plant production environment, how much influence. For the insulation layer loss blank place. To be replaced, the location of the insulation is not enough, should increase the thickness of the insulation layer, and strive to achieve the required thermal resistance coefficient.

The detection and control facility on the kiln is a key component for monitoring the temperature and pressure regime of the kiln as well as the temperature distribution inside the kiln. It enables us to grasp the actual condition of the kiln firing, provides basic real data for controlling the kiln firing, and is the basis for the kiln firing. When checking the testing and control facilities, first of all, we should check all the testing instruments and meters, so that their testing accuracy meets the requirements. Secondly, check whether the installation position is accurate and whether the data detected at that position reflects the actual situation in the kiln. Further, the loss of the opinion facilities during transmission should be calibrated to ensure that the transmission loss meets the requirements, and the transmission facilities that fail to meet the requirements should be replaced.

Although the brick billet entering the tunnel kiln is a dry billet, there will be a certain amount of moisture in it, which is called residual moisture content. As the kiln firing process is carried out at high temperatures, the residual moisture in the billet and the chemically bound water in the billet are discharged from the billet at lower temperatures. When the fire is re-lighted, the kiln is in a "cold" state, requiring a large amount of heat to heat the kiln body, according to a predetermined rate of heating, so that the kiln body and the billet is heated to the state parameters of the firing. If the residual moisture content of the billet is high, it will absorb a large amount of heat when warming up, which is a waste of energy, resulting in an increase in ignition energy consumption, or affect the ignition heating system, and affect the stability of the firing system. Therefore, again ignition, we should strictly control the water content of dry billet into the kiln, the drier the better, when the residual moisture content of the billet is greater than 7%, can not enter the kiln.

Lgnition, the kiln heating speed is not the faster the better, nor the slower the better. Kiln placed for a period of time without using, the kiln body to inhale a large amount of water, discharge this part of the water not only to absorb a large amount of heat, but also to pay special attention to the kiln body heating speed. Because, water in the process of changing from liquid to gaseous state in the volume to undergo a great change, about 22.4 times. If the heating up too fast. The water in the kiln body is not slowly evaporated, but a short period of time from the liquid more gaseous, then the volume expansion generated by the stress is very large, will produce great damage to the integrity of the kiln body, light body cracks, cracks, or the kiln body of the collapse. Kiln wall refractory materials used in the nature of its own requirements, making the kiln again when the ignition heating speed should be completed in accordance with a certain progress. Heating speed more than the refractory material allows the heating speed, will make the refractory material to produce cracking, heating speed is too slow will make the refractory material in the temperature of the weakest temperature under the time fast and long, will have a greater impact on the kiln wall or kiln roof strength.

Re-lighting, the kiln temperature rise fast or slow, whether in the optimal temperature rise speed range, and the speed of the feed car has a direct relationship. Ignition should be based on the position of the fire bed in the kiln, the kiln temperature distribution of the actual situation of each section, adjust the speed of the car, when the local temperature rises too quickly, should increase the car, and when the kiln temperature is too slow to enhance the car should be reduced, so that high-temperature billet car in the part to stay for a while, for the place to provide more heat.

The heat in the kiln is provided by the heat released from the chemical reaction between the fuel and oxygen combined. When the amount of fuel and the amount of oxygen are properly matched, the maximum heat can be released and the temperature can be raised to the optimum state. At the same time, the brick and brick billet and hot gas is by convection heat transfer for heat exchange. If the air volume is too large, although the integrated heat transfer coefficient is large, but because of the wind temperature is low, the temperature difference between the gas and the brick is small, the total heat transfer is small, is not conducive to the increase in temperature of the kiln. If the wind is too small, although the wind temperature is high, the temperature difference between the gas and the brick is large, but due to the integrated heat transfer coefficient is small, the total heat transfer will not be very large, the same is not conducive to the increase in kiln temperature. Only when the amount of fuel in the kiln and air volume are appropriate, the gas and the brick has a more appropriate temperature difference between the integrated heat transfer coefficient is large, then the total heat transfer is also the largest, will make the kiln warming very quickly. Therefore, the tunnel kiln can be controlled by controlling the amount of ventilation in the kiln, to control the tunnel kiln re-lighting when the heating speed.

Re-ignition, the operation of the tunnel kiln only rely on the inspection of the tunnel kiln, is not to ensure that the tunnel kiln again on the ignition of the tunnel kiln will be able to run smoothly, careful and operation in order to make the ignition process gradually transition to normal operation.

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