Rotary hearth furnace for calcining fine limestone

Abstract

The utility model discloses a rotary hearth furnace for calcining fine limestone. The rotary hearth furnace comprises a rotary hearth and a fixed furnace body, an opening of the fixed furnace body is provided with a discharge area and a distribution area, and is provided with a spiral roller, a scraper and a distributor. The annular cavity is sequentially divided into a primary preheating chamber, a secondary preheating chamber, a calcining chamber and a cooling chamber through partition walls. And the cooling chamber is connected with an air blower through a pipeline. Every two adjacent chambers are communicated through a communicating pipe. And the gap of the driving wheel is matched with the pin rod to rotate the furnace bottom. The distribution coulter promotes uniform distribution and turning of limestone, and improves the heat exchange efficiency. According to the utility model, the calcination of fine limestone is realized, and high-calcium limestone is saved.

Description

Technical Field

[0001] The utility model is applied to the field of lime production and relates to the calcination of fine limestone, in particular to a rotary hearth furnace for calcination. Background Art

[0002] Active lime is a key raw material in metallurgy and is also widely used in flue gas desulfurization and wastewater treatment. Active lime is calcined from limestone. Depending on the particle size of the limestone, different calcination furnace types are used. Limestone between 10mm and 40mm is typically calcined in a rotary kiln, while limestone between 40mm and 80mm is typically calcined in a vertical kiln. However, fine limestone less than 10mm in size suffers from poor air permeability when calcined in vertical or rotary kilns due to its small particle size, compromising safe operation. Currently, no suitable calcination furnace is available, and the material is typically crushed into sand and gravel for use as building materials. This processing method results in waste of high-calcium limestone. To conserve resources, it is necessary to design a furnace capable of calcining fine limestone. Utility Model Content

[0003] The technical problem solved by the utility model is to provide a rotary hearth furnace for calcining fine limestone, which can realize the calcination of fine limestone by reducing the thickness of the calcination layer.

[0004] The technical solution adopted by the present invention is as follows: the rotary hearth furnace for calcining fine limestone of the present invention comprises a rotating furnace bottom and a fixed furnace body. The fixed furnace body is a circular cavity with an opening, and the position of the opening is the discharge area and the distribution area; the circular cavity is divided into a primary preheating chamber, a re-preheating chamber, a calcining chamber and a cooling chamber in sequence by partition walls along the rotation direction of the furnace bottom. The preheating chamber is connected to the exhaust duct, and the cooling chamber is connected to the blower through a pipe. Adjacent chambers, such as the primary preheating chamber and the re-preheating chamber, the re-preheating chamber and the calcining chamber, and the calcining chamber and the cooling chamber, are connected by a connecting pipe. A spiral roller and a scraper are provided in the discharge area for unloading lime, and the scraper is provided behind the spiral roller. A distributor is provided in the distribution area for distributing fine limestone.

[0005] Furthermore, the rotating furnace bottom is powered by a driving device, and a driving wheel of the driving device is machined with notches that are evenly distributed around the circumference and cooperate with pins fixedly installed on the rotating furnace bottom, and is suitable for large steel structures.

[0006] Furthermore, a material dividing plow is fixedly installed on the lower end of the plane of the partition wall facing the limestone. The material dividing plow promotes the uniform distribution of the limestone and can turn the limestone to improve the heat exchange efficiency.

[0007] Furthermore, in order to ensure the sealing effect of each chamber of the fixed furnace body, the rotating furnace bottom and the fixed furnace body are sealed with a water seal structure. In order to prevent the water seal structure from affecting the unloading of lime, the water tank of the water seal structure is set under the refractory bricks of the rotating furnace bottom.

[0008] Furthermore, the rotating furnace bottom is a circular steel structure. To ensure the smooth rotation of the rotating furnace bottom, a rotating wheel is installed at its bottom, and the rotating wheel runs on a circular track. A rotating shaft is set at the center of the rotating furnace bottom, and the rotating shaft is connected to the rotating furnace bottom through the steel structure.

[0009] The beneficial effects of this utility model include: controlling the thickness of the fine limestone layer, achieving calcination of fine limestone and conserving high-calcium limestone. The drive wheel notches and pins are more compatible with large steel structures, and the material-dividing coulter helps increase the thickness of the fine limestone layer, improving heat exchange efficiency. The utility model directs heated limestone and combustion-supporting gas into the calcination chamber, fully utilizing thermal energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is the main view of the utility model, and also Figure 4 BB cross-sectional diagram;

[0011] Figure 2 yes Figure 1 A magnified schematic diagram of a local area A;

[0012] Figure 3 yes Figure 2 Schematic diagram of CC cross-section;

[0013] Figure 4 yes Figure 1 Schematic top view of

[0014] Figure 5 yes Figure 4 A local D enlarged schematic diagram;

[0015] Among them: 1- driving device, 2- rotating wheel, 3- track, 4- rotating shaft, 5- rotating furnace bottom, 6- spiral roller, 7- fixed furnace body, 8- distributor, 9- connecting pipe, 10- partition wall, 11- fine material limestone layer, 12- water seal structure, 13- pin rod, 14- driving wheel, 15- scraper, 16- burner, 17- blower, 18- material distribution plow;

[0016] 20- material distribution area, 21- primary preheating chamber, 22- re-preheating chamber, 23- calcining chamber, 24- cooling chamber, 25- material discharging area. DETAILED DESCRIPTION

[0017] The accompanying drawings of this utility model are schematic diagrams of the structure. For the sake of simplicity, structures not particularly relevant to this utility model are not shown in the drawings. The structures of the drive device, runner, shaft, spiral roller, distributor, burner, blower, material distribution plow, connecting pipe, and other components are all prior art.

[0018] The utility model is an improvement on the basis of a rotary hearth furnace used for ironmaking and is suitable for calcining fine limestone.

[0019] The structure of the utility model rotary hearth furnace is shown in the attached figure. Figure 1 and attached Figure 4 As shown, it includes a rotating furnace bottom 5 and a fixed furnace body 7. The rotating furnace bottom 5 is an integrated annular steel structure. The top surface of the rotating furnace bottom 5 is paved with refractory bricks, and a runner 2 is fixedly installed at the bottom. The runner 2 runs on the track 3. The track 3 is a circle fixed on the base plate to ensure that the rotating furnace bottom 5 is positioned and rotates around the center of the circle. A rotating shaft 4 can also be set at the center of the rotating furnace bottom 5, and the rotating furnace bottom 5 is connected to the steel structure so that the rotating furnace bottom 5 rotates around the rotating shaft 4. The rotating shaft is designed to allow the rotating furnace bottom 5 to rotate around a fixed center of the circle and play a limiting role so that the driving wheel 14 of the driving device 1 and the pin rod 13 on the rotating furnace bottom 5 can be accurately matched. If the track 3 can limit the rotation of the rotating furnace bottom 5 and ensure the matching of the driving wheel and the pin rod, the rotating shaft can be omitted.

[0020] The fixed furnace body 7 is not a closed integral ring, but a ring with an opening. Figure 4 As shown, the opening position is the discharge area 25 and the cloth area 20. The spiral roller 6 and the scraper 15 are set in the discharge area 25, as shown in the attached Figure 5 As shown, a scraper 15 is positioned behind the spiral roller (in the direction of the furnace bottom's rotation). A distributor 8 is provided in the distribution area 20. The annular furnace chamber is sequentially divided by partition walls 10 into a preheating chamber 21, a reheating chamber 22, a calcining chamber 23, and a cooling chamber 24, along the direction of the furnace bottom's rotation. These adjacent chambers are connected by connecting pipes 9 at the furnace top. The inner walls of all chambers and connecting pipes 9 are lined with refractory bricks. Burners 16 are installed on the side walls of the calcining chamber 23 to provide fuel for the calcination of the limestone. The fuel can be gaseous, solid, or liquid. The preheating chamber 21 is connected to an exhaust duct, which in turn connects to a dust collector. The cooling chamber 24 is connected to a blower 17 via a duct.

[0021] Attachment Figure 4The solid arrows in the figure represent the direction of material flow, or the direction of rotation of the furnace hearth. Fine-grained limestone is fed from the distributor 8 into the rotating furnace hearth 5 in the distribution area 20 and rotates with the hearth. The fine limestone layer 11 on the rotating furnace hearth 5 is heated in the primary and secondary preheating chambers, then calcined into lime in the high-temperature calcining chamber. The high-temperature lime then exchanges heat with the incoming cold air in the cooling chamber. The cooled lime enters the discharge area, where it is first discharged by the rotating spiral roller 6. Any lime remaining on the refractory bricks at the furnace hearth is then collected by the scraper 15 and discharged again by the spiral roller. The dotted arrows indicate the direction of gas flow. The cold air supplied by the blower to the cooling chamber is heated by the high-temperature lime before entering the calcining zone through a connecting pipe, providing combustion-supporting oxygen. Typically, the burner provides 15%-30% combustion-supporting oxygen to ensure a continuous burner flame, and 70%-85% combustion-supporting oxygen after heating to ensure a uniform calcination temperature for the limestone. The high-temperature exhaust gas from the calcining chamber enters the reheating chamber and the primary preheating chamber through the connecting pipe, exchanges heat with the limestone, and finally flows into the dust collector through the pipe on the top of the primary preheating chamber and is discharged outside.

[0022] The rotation of the rotary furnace bottom 5 is powered by the driving device 1. Figure 2 and attached Figure 3 As shown, the drive device includes an electric motor (or hydraulic motor), a reducer, a drive wheel 14, and other components. The drive wheel 14 is machined with notches evenly distributed around its circumference, which engage with pins 13 fixedly mounted on the rotating furnace hearth 5. When the drive wheel 14 rotates under the drive device's influence, the force exerted by the drive wheel 14 on the pins 13 causes the rotating furnace hearth 5 to rotate. The accompanying drawings show that the drive device is mounted on the outer circumference of the rotating furnace hearth 5, and the corresponding pins 13 are also fixedly mounted on the outer circumference of the rotating furnace hearth 5, and similarly on the inner circumference.

[0023] In order to ensure the sealing of the furnace cavity, a water seal structure 12 is used to seal the side of the fixed furnace body 7 and the rotating furnace bottom 5. Figure 2 As shown, the water trough of the water seal structure on the rotary furnace bottom 5 is arranged below the refractory bricks to facilitate the unloading of limestone.

[0024] A material distribution plow 18 is fixedly installed at the lower end of the partition wall facing the limestone plane. When the rotating furnace bottom 5 drives the fine limestone to rotate, the material distribution plow 18 can promote the uniform distribution of the limestone and also has the function of turning the limestone, so that the limestone and the high-temperature exhaust gas can fully exchange heat.

[0025] The utility model uses the notches and pins on the driving wheel to drive the rotating furnace bottom, which is more adaptable to the manufacturing and installation errors of large steel structures. Limestone has poor thermal conductivity. Using a material dividing plow to stir the limestone is beneficial to increase the thickness of the fine limestone layer and improve the heat exchange efficiency. The utility model converts the vertical reversal of materials and gases in the lime shaft kiln into a horizontal reversal. The combustion air is heated by the high-temperature lime after calcination, and the limestone is heated by the high-temperature exhaust gas. The heated limestone and the combustion gas both enter the calcination chamber, making full use of the thermal energy. The utility model realizes the calcination of fine limestone by controlling the thickness of the fine limestone layer, saving high-calcium limestone.

Claims

1. A rotary hearth furnace for calcining fine limestone, comprising a rotating hearth and a fixed furnace body; characterized in that: The fixed furnace body is a circular cavity with an opening, and the opening is located at the discharge area and the distribution area; the circular cavity is divided into a primary preheating chamber, a secondary preheating chamber, a calcining chamber and a cooling chamber in sequence by partition walls along the rotation direction of the furnace bottom; the preheating chamber is connected to the exhaust duct, and the cooling chamber is connected to the blower through a pipe; the primary preheating chamber and the secondary preheating chamber, the secondary preheating chamber and the calcining chamber, and the calcining chamber and the cooling chamber are connected by connecting pipes; The discharging area is provided with a spiral roller and a scraper, and the scraper is arranged behind the spiral roller; the distributing area is provided with a distributor.

2. The rotary hearth furnace for calcining fine limestone according to claim 1, wherein: The rotating furnace bottom is powered by a driving device. A driving wheel of the driving device is machined with notches that are evenly distributed around the circumference and cooperate with pins fixedly installed on the rotating furnace bottom.

3. The rotary hearth furnace for calcining fine limestone according to claim 1, wherein: The partition wall is fixedly installed with a material dividing plow on the lower end of the plane facing the limestone.

4. The rotary hearth furnace for calcining fine limestone according to claim 1, wherein: The rotary furnace bottom and the fixed furnace body are sealed by a water seal structure, and a water tank of the water seal structure is arranged below the refractory bricks of the rotary furnace bottom.

5. The rotary hearth furnace for calcining fine limestone according to claim 1, wherein: The rotary furnace bottom is a circular steel structure with a rotating wheel installed at the bottom, and the rotating wheel runs on a circular track.

6. The rotary hearth furnace for calcining fine limestone according to claim 5, characterized in that: A rotating shaft is arranged at the center of the rotating furnace bottom, and the rotating shaft is connected to the rotating furnace bottom through a steel structure.

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