Product Introduction:
To some extent, The thermal insulation performance of the rotary kiln body itself is an important factor leading to high energy consumption. At present, the existing rotary kilns generally have poor thermal insulation performance and serious energy waste, which is also a commonality in the field of rotary kilns all over the world. The ideal thermal insulation layer of a rotary kiln must have the advantages of both ultra-high strength and ultra-low thermal conductivity. However, these two indicators are usually inherently contradictory, which is difficult to have them on one kind of products.
The nano insulation module of the rotary kiln developed by our company perfectly solves this contradiction, which makes it possible for the rotary kiln to keep heat efficiently. It also fills the gap of ultra-high-strength of lightweight bricks in the international market.
Technical Data Sheet:
| Item | Parameters |
| Bulk Density (g/cm3) | ≤1.7 |
| Cold Crushing Strength (MPa) | ≥30 |
| Thermal Conductivity at 1000℃ (hot face) (W/m·K) | ≤0.3 |
| Long term Safety Working Temperature (℃) | 1300 |
Situation and Energy Consumption Analysis
Taking a clinker line with a daily production capacity of 5,000 tons, and the size of the rotary kiln is Ø4.8x72m as an example:
Usually, the cold surface temperature of large-scale cement rotary kilns is very high, which the kiln shell temperature is generally between 260 and 360℃, and it causes a lot of energy waste!
Kiln Shell Temperature and Heat Dissipation Consumption
The temperature of the combined part of the refractory bricks and the rotary kiln body is usually no more than 380℃, and the temperature will be about 400℃ when the red kiln phenomenon appears. The temperature of the combined surface of the kiln brick and the clinker or hot air flow is from 1,450℃ to 1,600℃. Therefore, it is required that when install the brick (normal bricks + joint bricks + steel plates), the bricks in the heated surface are 0~20mm less than the actual circumference. Considering the different expansion caused by the temperature difference, it is the principle of kiln bricklaying that the big head is squeezed tightly and the small head is appropriately loose.
At present, the surface heat dissipation of the new type dry cement kiln (from the grate cooler, kiln door hood, kiln cylinder, three-air duct, fed end chamber, decomposition furnace of back-end and preheater) is 8% to 13% of the total coal consumption of firing, and the heat dissipation of the kiln cylinder is 60% of the total heat dissipation of the whole system. That is to day, reduce the heat dissipation of the kiln cylinder can reduce the heat consumption of clinker.
The heat consumption of the new dry clinker line is 2,870~3,190kj/kg (686~762kcal/kg). In normal production, the temperature of the kiln shell is between 260℃ and 360℃, and the heat dissipation of the kiln cylinder is about 137~248kj/kg (32.7~59.3 kcal/kg) of the firing heat consumption, which is 4.7% to 7.8%.
Recommended Solution and Energy Saving Ratio
Our company recommends the following masonry solution to reduce the heat dissipation of the burning zones:
The nano insulation module of the rotary kiln produced by our company can be perfectly matched with the current working lining bricks like magnesia-aluminum spinel bricks, magnesia-aluminum-iron spinel composite bricks, and silicon mullite bricks for rotary kiln. The use of anhydrous high-temperature binder during installation can reduce the joints among the nano insulation modules, the rotary kilns bricks and also the rotary kiln cylinder greatly.
According to the calculation of the heat dissipation characteristics of the temperature gradient, we recommend to use nano-insulation modules with a thickness of 30 to 40mm in the rotary kiln, which can reduce the surface temperature of the kiln shell by at least 100℃. That is to say, the maximum temperature of the kiln shell will be below 260℃. According to the “Energy Efficiency Benchmarking Guide for Cement Enterprises 2008”, when the surface temperature of the rotary kiln decrease every 30℃, it can save energy of 7kcal/kg, which is equivalent to 1kg of standard coal. About 60% to 70% of the whole rotary kiln can use this nano insulation module, which can save coal consumption as follows: 100÷30×65%=2.17kg/T.
At present, the average annual standard coal consumption per ton of clinker for the rotary kiln is about 105kg/t. The coal consumption savings per ton of clinker are about 2.1%. That is to say, the production line with an annual output of 1.5 million tons of clinker can save: 2.17kg/t×1.5 million÷1,000=3,255 tons of standard coals.
Schematic diagram of brick masonry in rotary kiln:
In today’s fierce competition in various industries, large-scale thermal equipment does need a product that has both ultra-high compressive strength and high-efficiency thermal insulation ability to improve its core competitiveness. In the future, after the full promotion and application of this product, it can reduce costs and increase efficiency for enterprises. It can also save a lot of fuel for the country every year, which can achieve huge social benefits while also making due contributions to the national environmental protection.
