Characteristics of lime kiln and refractory material selection

There are many different ways to classify kilns. More generally, they are classified according to the physical state of the roasted products, combined with the production method.

The kiln type of lime kiln is commonly used in the building materials industry, many of its predecessors were used in the cement industry, cement kiln for burning clinker, in recent years, through the introduction of many foreign technologies and to develop China has a variety of advanced kiln type suitable for lime production.

1、By fuel: there are mixed kilns (i.e. burning solid fuels, coke, coke powder, coal, etc.) and gas-fired kilns.

2、Burning blast furnace gas, coke oven gas, calcium carbide tail gas, coal gas from the generator, natural gas, etc.).

3、By kiln shape: there are vertical kiln, rotary kiln, sleeve kiln, double-bore kiln, double-beam kiln, etc.

4、According to the operation pressure: there are positive pressure operation kiln and negative pressure operation kiln.

Basic structure and equipment of lime kiln

Lime kiln structure is simple, the production process control is convenient and reliable, less wearing parts, high operation rate, advanced structure, low pressure loss of the vertical preheater can effectively improve the preheating effect, after preheating limestone into the very lime kiln decomposition rate of up to 20-25%, and can directly use 10-15mm fine-grained limestone; reliable lime kiln two ends of the combined scale seal. It is the equipment for calcining high-grade cement in cement plant, and also widely used in metallurgy, chemical industry, construction and other industries.

Iron and steel industry, calcium carbide industry, alumina industry, refractory materials and other industries are all big consumers of lime, and these industries are the industries of high speed development in the last two years. The annual production is basically growing at a rate of more than 20%. The main component of limestone is calcium carbonate, and the main component of lime is calcium oxide. The basic principle of burning lime is to decompose calcium carbonate in limestone into calcium oxide and carbon dioxide quicklime with the help of high temperature.

The main auxiliary equipment of lime kiln are feeding mechanism, fabric, air supply device, combustion device, ash discharging device, etc. Relatively speaking, the fabric of mixed lime kiln is very critical because it must load fuel and limestone into the kiln at the same time, realize the reasonable distribution of furnace material in the kiln through the fabric, eliminate the wall effect, equalize the resistance in the furnace, and strive to “fire” the whole furnace section “The kiln is equipped with the following equipment

The main accessory equipment of gas-fired kiln is the burner, because its gas fuel is fed into the furnace for combustion through the burner by mixing the combustible gas and the required oxygen (air) in a certain ratio in the burner, and the amount of air required for different gases is also different. Different furnace types, different heating methods, it requires different types of flame, such as premixed, semi-mixed, external mixed and oxidation flame, neutral flame, reduction flame, etc.. Therefore, the burner of gas kiln determines the calcination effect of lime kiln to a certain extent.

Of course, other ancillary equipment is also very important, such as the wind cap, look similar is very simple, but to ensure that it supplies the kiln air volume in the entire kiln section of the distribution of good results.

Basic principle and thermal process of lime kiln

Qualified limestone is stored in the silo, lifted by the hoist and transported into the top bin of the preheater. The top bin of the preheater is controlled by 2 level meters, and then the limestone is evenly distributed to each chamber of the preheater through the lower feeding pipe. The main equipment of energy-saving and environment-friendly active lime rotary kiln calcination system includes vertical preheater, transfer chute, rotary kiln, combustion device, vertical cooler, pulse bag filter, etc. The whole system has reliable operation, high automation and labor productivity, and good product quality.

The fuel for burning lime is wide, solid fuel, gas fuel and liquid fuel are all available, but the combustion principle of new technology lime kiln is that the kind of fuel is the most economical, the kind of fuel is more conducive to environmental protection, those fuels are more energy-saving is the key of new technology lime kiln. The main component of limestone is calcium carbonate, and the component of lime is mainly calcium oxide. The basic principle of lime firing is to decompose calcium carbonate in limestone into calcium oxide and carbon dioxide with the help of high temperature.

Thermal insulation materials for lime rotary kiln

In many production industries such as building materials, metallurgy, chemical industry and environmental protection, rotary kiln equipment is widely used for mechanical, physical or chemical treatment of solids, powders, gases and other materials, and this type of equipment is called rotary kiln. Another type of kiln barrel is standing and not rotating is called vertical kiln. The main equipment of rotary kiln is the kiln shell, which is the main body of rotary kiln (rotary kiln), the thickness of the kiln shell steel plate is about 40mm, and the temperature in the kiln shell should reach about 1000 degrees Celsius, and the high temperature should reach 1600 degrees Celsius. The traditional kiln shell has a layer of 200mm refractory bricks or silicon carbide bricks inside for better heat insulation, so the kiln shell has a large weight ratio.

Heat insulation and thermal insulation material of rotary kiln, high temperature resistant heat insulation and thermal insulation coating, coating for water-based inorganic coating, using high temperature solution and selected nano-ceramic hollow micro-beads, hollow micro-beads and other inorganic raw materials refined and processed, temperature resistance range of -80-1800 ℃, thermal conductivity of only 0.03W/m.K, small specific gravity, light weight, can greatly reduce the painting object weight of the painted object. High temperature heat insulation and thermal insulation coating can effectively inhibit and shield the infrared radiation heat and heat conduction heat, heat insulation and thermal insulation inhibition efficiency can reach about 90%, can inhibit the heat radiation of high temperature objects and heat conduction dissipation, the internal heat of rotary kiln can keep 70% not dissipated, in addition coating fire retardant, wear resistance and pressure resistance, insulation anti-breakdown, acid and alkali resistance, light weight, convenient construction, long use cycle, etc.