Firebrick linings

Probably the rotary horizontal kiln is the most versatile, since it allows a feed of lumps or fines of limestone or marble, or wet or dry calcium carbonate sludges (Fig. 7.1). The main component of this calcination system is a 2.5- to 3.5-m diameter by 45- to 130-m long firebrick-lined inclined steel tube. Heat is applied to the lower end of this via oil, gas, or coal burners [7]. The feed to be calcined is fed in at the top end. Slow rotation of the tube on its axis gradually moves the feed down the tube, as it tumbles countercurrent to the hot combustion gases. In this way, wet feed is dried in the first few meters of travel. Further down the tube, carbon dioxide loss begins as the temperature of the feed rises. By the time the solid charge reaches the lower, fired end of the kiln it reaches temperatures of 900-1,000°C and carbon dioxide evolution is virtually complete. Normally the temperature of the lower end of the kiln is not allowed to go much above this as it reduces the life of the kiln lining. It also adversely affects the crystal structure of the lime product since it produces a dead-burned or overburned lime. Overburned lime is difficult to slake to convert it to calcium hydroxide and raises... 

V2O5 residues from fuels irritating to those who clean oil-fired burners, renew firebrick linings, and clean heat-exchanger tubes (dusts contain 6-20% V)... 

Thermal Process. In the thermal process, the carbon black is formed by the thermal decomposition of natural gas in the absence of air in a preheated firebrick-lined chamber. The process produces a coarser grade than the channel process with particle size up to 500 nm and lower surface area. 

Some of the high-temperature transfer lines are protected by castable or firebrick linings, with the outer retaining piping water-cooled. The inner refractory liners also are protected by shrouds of Type 304 or 321 stainless steel. 

When heavier refractories are required because of operating conditions, insulating brick is installed next to the shell and firebrick is installed to protect the insulating brick. Industrial experience in many fields of application has demonstrated that such a lining will successfully withstand the abrasive conditions in the bed for many years without replacement. Most serious refractory wear occurs with coarse particles at high gas velocities and is usually most pronounced near the operating level of the fluidized bed. 

Whatever the process, the steelmaking vessel must be lined with a suitable refractory material, usually bricks of calcined dolomite, (Mg,Ca)0. Silicate firebricks cannot be used in the presence of lime. 

The purification of ammonium chloride.—Crude sal ammoniac is usually contaminated with iron or tarry matters, and in consequence, the colour varies from yellow to red it can be purified by heating it in thin layers on an iron plate hot enough to drive off the water and free acid, and to carbonize most of the tarry products. The grey mass is then sublimed. The sublimation is conducted in cast-iron pots lined internally with firebricks, and covered with a lid made of slightly concave plates. The salt to be sublimed is well dried, and heated. The pots hold about half a ton, and the sublimation occupies about five days. The sublimate forms a solid fibrous crust about 4 inches thick. The crust is easily detached from the lid it is then broken up, separated from adhering dirt, and packed for the market in barrels or sacks. W. Hempel 9 proposed converting the crystalline salt into hard stone-like masses by press, between 50° and 100°. 

Figure 17-3 shows a steel vessel lined with block under insulating firebrick and acid brick. At high operating temperatures, a proper brick thickness reduces the temperature on the block to 800°F or below. The maximum temperature limit for the block under brickwork or any other organic lining is 800°F. This limit, lower than the 960°F for the block alone, is necessary because the load placed on the block by another lining material may cause the block to creep and distort at temperatures above 800°F. 

Figure 1.5-3 shows a process flow sheet for the electrothermal manufacture of phosphorus. The electrothermal reactor, which is round or triangular with rounded corners, is lined with carbon blocks at the bottom and otherwise with firebricks. The symmetrically... 

FIREBRICK - A refractory brick, often made from fire clay, that is able to withstand temperature in the range of 1500 to 1600°C, and is used to line furnaces. 

Combustion chamber- The part of a boiler, furnace or woodstove where the bum occurs normally lined with firebrick or molded or sprayed insulation. 

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