working principle

The materials in the closed rotary kiln do not come into direct contact with the flame and flue gas. The heat source flows in the interlayer between the rotary drum and the external sleeve. The system mainly heats the materials through heat transfer through the heat-resistant steel drum wall of the rotary drum. It is particularly suitable for special working conditions such as processing highly toxic materials, high flue gas concentration, high product purity, acidification reaction, low oxygen or anaerobic reaction, etc.

Workflow

The materials to be processed by the user are evenly fed into the kiln barrel from the kiln head hopper (other reactants such as sulfuric acid are added at the kiln head).

Driven by the transmission device, the materials are turned over by the spiral or the lifting plate, and move along the axial direction of the barrel as the barrel rotates, so that they are calcined and reacted evenly.

A heating chamber or a heating jacket is provided on the outside of the barrel. The heating chamber can be directly fired or a hot air circulation heating system can be used according to different processes. The heat source heat is transferred to the material through the barrel, and the material reacts, decomposes, dries, calcines and roasts at a suitable high temperature.

The processed materials are discharged through the kiln tail discharge valve, and enter the next process after cooling. The reaction gaseous by-products are discharged on the upper side of the kiln tail and enter the next process.

System Applications

The closed rotary kiln system is widely used in building materials, metallurgy, chemical industry, non-ferrous metals and other industries. It is not only used for drying and roasting chemical powders and granular materials, but also for drying, roasting and decomposing metal oxides, drying and roasting of inorganic salts and rare earth materials.

System Category

1. Externally heated rotary reactor

2. Closed rotary kiln system

3. External circulation rotary kiln

4. Externally heated rotary kiln

5. Indirect Heating Rotary Kiln

6. Indirect Fired Rotary Kiln

7. Waste tire cracking heating system

8. Coal pyrolysis and upgrading rotary kiln heating system

9. Distillation kettle heating system

10. Fluorine chemical rotary kiln heating system

11. Lithium chemical acidification kiln heating system

Equipment Characteristics

1. Even distribution of hot air to achieve precise temperature control

There is an insulation cover outside the heating jacket, and a heating chamber is formed between the jacket and the cylinder. The hot air inlet jacket and the cylinder are eccentrically designed, and an arc-shaped diverter plate is set at the inlet to diffuse the hot air to the surroundings. The inner layer uses a heat-resistant stainless steel perforated plate to evenly distribute the hot air into the jacket. A sandwich space is formed between the hot air jacket and the cylinder for the hot air to pass through. A spiral structure is designed in the sandwich or on the cylinder to ensure the fullness of the hot air in the sandwich, extend the hot air residence time, and improve the heating function. A thermocouple is set in the cylinder to measure the temperature inside the cylinder, and the central control system is connected using wireless transmission technology. Different heating sections are required according to the process temperature, and each section corresponds to a separate heating jacket, so as to control the temperature of different process sections and achieve precise control.

2. Stable structure and good sealing

The rotary kiln cylinder is made of high temperature resistant material, and the cylinder is designed with unequal thickness. The cylinder is thick in the bending stress section. The tail end is supported by a supporting wheel, with a large contact area. The thermal expansion can be released in time to reduce the damage of the cylinder to the internal stress. The sliding end jacket base is equipped with a directional sliding block to meet the movement of the jacket due to thermal deformation. The inlet and outlet seals of the furnace head and furnace tail are equipped with expansion joints, and the inlet and outlet seals are mechanically sealed + air curtain to prevent material leakage. The jacket and the cylinder dynamic seal use graphite blocks to prevent hot air from overflowing.

3. Smooth material in and out, evenly heated

The inlet and outlet spirals are designed at the feed and discharge ends of the cylinder to promote the material to enter and discharge the cylinder. A shoveling plate is set in the cylinder according to the actual material to be processed to stir the material so that it is evenly heated. The folding direction of the shoveling plate in the cylinder is opposite to the direction of the cylinder. While turning the material to ensure uniform heating, it reduces the height of the material drop to prevent the material from breaking.

4. High operating rate, energy saving and environmental protection

The hot air recycling scheme is adopted to make the use efficiency of the external heating rotary reactor higher, save fuel, and achieve the purpose of reducing costs and increasing efficiency.

5. Interlocking protection, high degree of automation

 The system has display and interlocking alarm of temperature, pressure, equipment speed, etc., and automatically selects the corresponding interlocking protection according to the fault signals of different equipment. At the same time, PLC is used for control and management, and the process temperature of each section of the jacket can be set online in sections, automatically adjusted, and automatically controlled to meet production needs.