The production technology of shuttle kiln

Shuttle kiln is a new type of intermittent kiln which can replace inverted kiln. It is one of the most rapidly developed kilns in recent ten years. Shuttle kiln is a kind of thermal equipment with kiln car as the bottom of inverted flame (or half inverted flame) intermittently production. Also called car bottom type inverted flame kiln, because the kiln car from one end of the kiln in and out also called drawer kiln. Shuttle kiln not only has the advantages of flexible operation of general inverted kiln, and can meet the requirements of multi-variety production, but also can carry out the cooling of loading kiln, discharging kiln and part of products outside the kiln, which not only improves the working conditions, but also can shorten the kiln turnover time and increase productivity. However, due to intermittent firing, the heat storage loss and heat dissipation loss of the kiln are large, the flue gas temperature is high, and the heat consumption is high. The new type of shuttle kiln with energy saving improves the masonry structure of the kiln and adds a device to use waste gas and heat, which greatly improves this shortcoming.

Currently, the volume of shuttle kiln in China is generally within the range of 10~80m. Recently, 300m shuttle kiln for firing silicon bricks has been introduced. Shuttle kiln firing temperature 1000~1800℃, can use natural gas, gas, diesel oil, liquefied gas and so on as fuel. Shuttle kiln is mainly used for the production of high-grade refractory, such as magnesia products, sliding plate, shuikou, corundum brick, kiln furniture and other refractory. All kinds of shuttle kilns adopt appropriate measures to recover flue gas waste heat, and the fuel consumption of light energy saving shuttle kilns is only 30%~40% of that of ordinary down-shot kilns.

Typical shuttle kiln is characterized by light weight, thin wall and energy saving. Its main characteristics are as follows :(1) it can adapt to multi-varieties and small batch production, organize production flexibly, and meet the requirements of production based on sales. (2) Light-weight thin-wall kiln wall structure is adopted. The lining is made of high-temperature lightweight material with good heat insulation and less heat storage. (3) The new shuttle kiln adopts high-speed isothermal burner, which is arranged at random and spews out high-speed airflow, so that the airflow in the kiln rotates strongly and the convective heat transfer effect is greatly improved. The temperature difference between each point in the kiln at high temperature can be controlled within 5℃. In the low temperature stage, temperature-regulating air is used to increase the amount of smoke and adjust the temperature of flue gas injected into the kiln. The temperature difference in the kiln is between 5 ℃ and 10℃. The heating and cooling speed is fast, and the firing period is short. (4) Loading and unloading bricks were carried out outside the kiln, and the working conditions of production were greatly improved. (5) Suitable inspection instrument can be prepared and PLC controlled to realize full automation operation.

At present, shuttle kilns with a firing temperature of 1750~1800 ° C mostly have a volume of 3~15m, those with a firing temperature of 1500~1700 ° C mostly have a volume of 15~60m, and those with a firing temperature of less than 1500 ° C mostly have a volume of 20~120m. Shuttle kiln can use natural gas, gas, diesel oil, liquefied gas and so on as fuel. The new type of shuttle kiln is a kind of light, thin-wall, high-temperature and energy-saving thermal furnace developed by Anshan Coking refractory design and Research Institute in the early 1990s. It was awarded the national utility model patent in 1995. In recent years, in order to adapt to the development of the market economy, refractory manufacturers have been constantly adjusting the product structure to make the product structure more diversified, which requires that calcining kiln can meet the requirements of producing a variety of flexible characteristics, so shuttle kiln is widely used. It is mainly used in the production of high-grade refractory, such as magnesia products, skateboards, shuikou, corundum bricks, kiln furniture and other refractory.

The production system of shuttle kiln consists of fuel supply and combustion equipment, combustion fan, flue gas - air heat exchanger, temperature regulating fan and exhaust fan. The kiln body of shuttle kiln is rectangular, and the masonry of kiln wall is divided into three layers along the thickness direction. The working lining is made of high-strength and high-grade refractory brick, the interlayer is heat-insulating refractory material, and the outer layer is made of refractory fiber felt affixed to the kiln wall. The kiln roof is made of flat suspended ceiling structure, and the masonry is divided into three layers. The inner layer is high strength high-grade thermal insulation brick, which is hung below the suspended ceiling brick. The interlayer is thermal insulation brick, and the top layer is made of fire-resistant fiber felt, which is both thermal insulation layer and sealing layer. Due to the frequent movement of the kiln door, the masonry of the kiln door is divided into two layers, the inner layer is high-strength high-grade thermal insulation brick, and the outer layer is thermal insulation layer. Refractory fiber felt is used to stick on the metal shell of the kiln door. The burner shall be installed on the wall of the kiln, with one or two rows depending on the height of the kiln. The kiln floor is taken as the kiln bottom and the kiln roof and wall constitute the kiln firing space. The main flue is left in the center of the kiln lining brick, which is connected with the underground flue. One end (or both ends) of the kiln is provided with a kiln door, which can be set up separately or masonry in the end of the kiln car. Skirt boards on both sides of kiln cars are inserted into the sand sealing groove of kiln walls. There are curved sealing grooves between kiln cars and kiln cars as well as between kiln cars and end walls and kiln doors. Refractory fibers are squeezed tightly to seal the kiln. There are many ventilation holes in the bottom of the sand sealing groove of kiln wall, which is beneficial to the heat dissipation at the bottom of kiln car and prolongs the service life of kiln car.

Shuttle kiln operation is: will be installed adobe kiln car a push kiln, kiln car mesa center main flue aimed at flue underground interface, closed wicket, start the fume extractor, combustion fan, air-conditioning fan, fuel supply, began to rise to ignition and combustion flue gas is sprayed into the stove kiln roof, back through the clamps down into the flue, the fume extractor (or) directly into the chimney to the atmosphere. The flue gas heats the product as it passes through the brick stack. The kiln reaches the highest firing temperature, and enters the cooling stage after a certain period of time. In the cooling stage, cut off the fuel and send low temperature hot air and air into the kiln for cooling. After the cooling, turn off all the fans, open the kiln door, pull out all the kiln cars, unload the finished products, and the firing cycle of the kiln ends.