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Following experimental work with the firing of large dinas articles [1][2][3], the Pervouralsk dinas factory has constructed and put to use a new tunnel kiln for these products. The project was designed by the All-Union and East institutes.The technical specifications are: length 243 m; number of cars in the channel (positions) 81; car's plan size 3.0 • 3.2 m; height from floor of car to Mln roof 1435 mm; firing temperature --up to 1450~ fuel --natural gas with a combustion heat of 34.4-35.7 mJ/m3; kiln output up to 40,000 tons a year, depending an the type of product.The kiln roof in the preheat and cooling zones is made of fiat-thrust chamotte and dinas goods. In the firing zone the roof is of the suspension type, made of high-alumina shapes. The arrangement of the zones in the tunnel kiln is shown in Fig. 1. Figure 2 shows the cross sections of the preheat and firing zones.Drying and Preheating in the Kiln. Drying and warming up of the kiln with a hydraulic valve in winter time are affected with heat generators designed by the East Institute, heated with natural gas. The generator was connected to the suction pipe of the fan designed for recireulation in the cooling zone. The gas--air mixture (125~ is impelled by fan into the kiln channel at the end of the firing zone. The front gaps of the kiln channel and the lower apertures in the walls were closed, and the connecting pipes for taking off the flue gases, and only the flue tract choke for the natural draft were left open.The temperature in the kiln channel was raised to 100~ on account of the heat from the thermal generator. This prevented freezing of the water in the hydraulic valve and the worldng of the kiln in winter time. The kiln channel was filled with cars and a setting of nonstandardized products. On the extreme car we established a temporary burner (Fig. 3). The rising temperature was recorded with Chromel--Alumei thermoelectric thermometers.The temperature was raised in line with the graph shown in Fig. 4. Up to 1200~ the kiln operated on natural draft. The draft at the floor level was 3-4 Pa. When 750~ was reached the first pair of main burners was lit. Further lighting of burners occurred at 700-800~After lighting the intermediate burners at the end of the firing zone the gas to the temporary burner was switched off, and the temporary gas duct was demolished. At the same time, the cars began to be pushed every 8 h. When the end of the firing zone reached 1250~ car-pushing started to be done every 4 h on this working schedule until the kiln was at the working temperature. Above 1000~ the temperature was measured with an optical pyrometer sighted on a brick placed in the middle column of the setting at a height of 600-700 mm from the car floor.When the burners were switched on a drop in pressure was established on the air consumption diaphragms of 0.7 kPa (about 83 m3/h). To ensure the same rise in temperature on both sides of the kiln, the gas and air consumptions an opposing burners were maintained at the same levels.When the suspension was weak...

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