1 main technical parameters and economic index
The tunnel kiln for open flame clearance combustion, intermittent into the car, burnt products for corundum mullite refractory brick, the whole kiln length 50 m, furnace width 1.5 m, kiln car mesa to kiln top height 0.95/0.75 m, kiln content kiln car 25 tanks, each a kiln car code with 2 a brick to buttress, firing temperature 1650 ℃, firing cycle and h, fuel gas, tons of brick energy consumption for 1500 kcal, kiln temperature and pressure for automatic control, temperature control accuracy ± 2 ℃ or less
2 body structure and working system of kiln
The whole kiln mainly includes the main structure of the kiln, the kiln head closed air curtain and exhaust system, mixing wind system, the combustion system, the end cooling system, car under cooling air system, waste heat utilization system, kiln car, automatic control system, etc., as shown in figure 1 shows. This kiln in kiln body structure, high temperature air combustion, waste heat utilization and automatic control adopted some new technology, and the traditional high temperature furnace were compared, and has high temperature firing control of high precision, energy-saving effect is remarkable characteristics.
2.1 the main structure of kiln
The kiln body steel structure with steel reinforcement column, the outer surface of the decorative paint handling of high-quality steel plate. The total length of the kiln 50m, divided into a preheating zone, firing zone and cooling zone Part 3. The burning zone lined with corundum mullite bricks, out of high temperature lightweight insulation tiles, insulation fillers, asbestos Xonotlite board. The kiln roof structure for the arch liners should be used in order to reduce the high-temperature expansion of the dome, a slightly lower density, expansion coefficient is small and homogeneous firebrick firing zone. In the preheating zone the vaulted masonry three interleaved baffle, so the part above the arch of the foot under the hot gas flow to baffle both reduce the preheating zone of the upper and lower temperature, it will not affect too much smoke pumping force. Traditional tunnel kiln outside the arch foot brick vault cross thrust, with a heavy brick building, this part of poor insulation. The design of the outside of the arch foot brick Zhiping tile Celi placed a certain distance away, fill the lightweight insulation tiles and bulk plate tile insulation material, which can effectively improve the insulation performance of the site.
2.2 Yaotou closed the air curtain and exhaust system
In order to maintain a stable kiln pressure, avoid firing temperature fluctuations, the kiln Yaotou the kiln inlet not set kiln door, the wind shield of an air curtain in the kiln head on both sides of the wall and the kiln top of each set, the ventilation in the form as a closed gas screen, change the traditional kiln door and hair closed form of air curtain, but also conducive to the products clean into the kiln firing. The exhaust system in the form of smoke and kiln kiln multi-point central exhaust fan. In the preheating zone of the kiln wall on both sides, setting the exhaust port. The exhaust port is located in the the kiln wall near the kiln car countertops Department. Meanwhile, the preheating zone is adjusted by adjusting the degree of opening of the exhaust port to the temperature curve. Each exhaust port provided on the outside the cold diluted mouth, if necessary, can be inhaled part of the kiln outside air to reduce exhaust gas temperature.
2.3 stirring wind system
Traditional tunnel kiln preheating zone due to gas stratification leads to the upper and lower temperature. Taken to the kiln the roof flow analysis and kiln multi-point exhaust measures, the design in preheating zone on both sides of the wall unit also has stirred the air system, pumped into the environment through the blower cold wind after Explorer, branch pipe, ball valve, into the kiln of the upper channel and stirred airflow prevents airflow stratification, thereby reducing the preheated to bring under the temperature difference. The air inlet small, staggered on both sides.
2.4 combustion system
Longer constant time requirements of high temperature firing products, thus the design firing with accounting for the proportion of the total length of the kiln body slightly larger number of burners arranged slightly more, adjusted by changing the number and location of the lit burner to burn into position and high temperature thermostat with high temperature point of time, can be adapted to the the firing process requirements of the different formulations of products with greater adaptability and flexibility of the firing process.
The staggered arrangement on both sides of the burner along the kiln, and being on the the combustion passage between the brick stack of the kiln car, therefore, high speed flow of combustion gas is not the relative flow, mutual interference, but the horizontal and vertical directions in the kiln to produce a certain cycle, the kiln temperature uniformity. Not on the kiln side wall is set in the combustion chamber, while the use of the way of the direct combustion in the kiln products, the sidewall structure more simple, fully insulation.
It should be noted that, a big difference in the kiln the combustion mode with the conventional tunnel kiln. Even if no combustion chamber to the traditional high-temperature tunnel kiln burner brick cavity large combustion air almost all or all through the burner or combustion chamber burner brick into the kiln combustion, combustion air heat exchanger mainly by achieved through the hollow arch and the cavity wall of metal heat exchanger or kiln heat exchanger temperature up to 1000 ℃, low of only 200 to 300 ° C; and the use of the furnace of masonry heat exchanger the way the combustion air pressure is not high, but also easy to causing the kiln ventilation, air leaks. The design of the new high-temperature kiln combustion chamber, burner blocks shorter and smaller chamber, only a very small part of the cold air through the burner into the kiln, from the role of cooling the burner and to help blow most of the combustion air from cooling with the cooling air into the drum. Cooling products after the hot air reaches the firing zone, the temperature is close to the highest temperature. Obviously, the energy saving effect of this kiln is remarkable, and high-temperature heating and high temperature thermostat operation easier.
2.5 kiln inlet cooling system
The kiln in the kiln inlet on both sides of the wall and the kiln top set a cold wind mouth, by the fan to the the kiln drum into a lot of cold air cooling products. In addition, it is still cooling with two kiln car joints on both sides of the top and bottom of the kiln wall staggered arrangement of the number of high-speed low-flow cold air blowpipe, cold wind blown form a section of a cooling in the kiln car joints, and contribute to the cross-section uniform cooling of the entire product . Most of the movement of hot air in the cooling products to combustion burning zone, with the remaining part of the cooling with air vents of the kiln wall by pumping hot air blower extracted and sent to the drying kiln.
2.6 car cooling air system
The kiln is a high temperature kiln, under the car in order to prevent overheating, the car has cooling air system. Set in the lower part of the firing zone and cooling zone of the kiln car air duct blowing cold air, next to the car through the air vents at the bottom of the kiln wall, the natural pumping force formed by the internal and external exhaust port height difference exclusion.
2.7 waste heat utilization system
The design of waste heat utilization system includes four parts: the outer surface of the heat sink cooling air cooling with a part of the cooling of hot air, cooling air under the car, the top of the kiln wall kiln hot air and flue-for. Due to the high temperature kiln surface temperature is slightly higher than the average tunnel kiln, in order to make full use of the waste heat in high temperature with kiln roof support section steel corrugated plate heat exchanger space and outer dome formation; kiln wall layer brick cavity wall cold air from near the ground a row of small holes into the hollow walls, kiln roof for hot air mixed concentrate extracted. In the kiln exhaust manifold equipped with a metal heat exchanger trail, can take full advantage of the part of the waste heat of the flue gas. More than four parts were sent to the waste heat wind drying kiln, can fully meet product drying needs.
2.8 kiln car
Kiln car section steel production processed meshing brick bearing bearing high temperature, the maximum temperature of 300 ° C, bodywork refractories: car station tile selection and good thermal shock resistance of sintered mullite brick, dry puzzle; surrounding selection The building; selection of insulation brick building in the middle. Turntable tile stem puzzle advantage can greatly reduce the number of kiln cars overhaul extension of the kiln car life.
The 2.9 automatically control system
The automatic control system for the kiln temperature control, pressure control and security alarm.
The firing temperature is controlled by computer, including computer AI Artificial Intelligence regulator, solenoid valves, electric actuators and thermocouple, and configure data acquisition card and the machine within a machine outside the isolation device programming and development, the use of a computer dedicated IPC package . Temperature thermocouple detection, to adjust the the fire of contention flame by the electric actuator, controlled by computer and AI regulator set the firing curve. The computer control system is not only able to automatically control the furnace temperature. Also enables integrated control system of the kiln, and can automatically record, print and screen language prompts; addition, the computer can simulate and store multiple firing system curve requirements under firing at the same time firing curve parameters can be need to be modified at any time.
The kilns pressure control by inverter control exhaust fan, cooling fan and hot air extraction fan. The kiln pressure signal and fan pressure of the main channel signal collected by a pressure transmitter, sent to each of the AI smart regulator, automatic conversion to adjust fan speed control and high precision, and power-saving. The use of a pressure transmitter by manually switching the pressure signal measured kiln from multiple sites hand operation and the inverter can be switched to manual operation environment, in order to process fumble, as well as to cope with emergencies.
The fuel used in the kiln for natural gas, in order to ensure the supply security has electromagnetic valve in the gas supply charge of road, also has a range of solenoid valves on each loop. When the power outage of the system, the solenoid valve is automatically cut off the gas line to prevent gas entering the kiln; When the the fan system fails, the alarm system alarm signal to the solenoid valve is automatically cut off the gas line to ensure safety.
3 Conclusion
On the design of a new type of high-temperature tunnel kiln in the kiln and combustion using a unique new technology, state-of-the-art performance and reliable once debugging success and put into normal operation. Put into operation, the technical and economic indicators of the kiln to achieve the design requirements, energy-saving effect is remarkable, it is worth about the new manufacturers or to transform high temperature tunnel kiln, or draw.
