Efficient clay suspension calcining system capable of controlling color of product

Abstract

The present invention relates to the technical field of clay calcination. Provided is an efficient clay suspension calcining system capable of controlling the color of a product. In the present invention, the concept of controlling a combustion atmosphere by means of air distribution is utilized, and the coefficient of excess oxygen in a main combustion chamber is controlled to be smaller than 1, thereby realizing calcination in a reducing atmosphere, and controlling the color of a clay product. Moreover, air is also distributed to a carbon monoxide eliminating chamber to make the coefficient of excess oxygen in the carbon monoxide eliminating chamber larger than 1.15, thereby eliminating unburnt carbon monoxide, and reducing the fuel consumption. Calcined clay firstly enters a first-stage heat exchanger, and the temperature of the calcined clay is reduced to 300ºC or lower by means of indirect heat exchange. After passing through the first-stage heat exchanger, heated conduction oil passes through a second-stage heat exchanger and a third-stage heat exchanger for heat recovery. The second-stage heat exchanger increases the temperature of air entering the main combustion chamber and the carbon monoxide eliminating chamber, thereby improving the combustion efficiency of fuel.

Description

High-efficiency clay suspension calcination system with controllable product color Technical Field

[0001] The invention relates to the technical field of clay calcination, in particular to a high-efficiency clay suspension calcination system with controllable product color. Background Art

[0002] When clay is calcined in a reducing atmosphere and cooled to below 300 degrees in an indirect heat exchange form, the product is gray. After being added to clinker and ground into cement, it does not affect the color of the cement. If clay is calcined in an oxidizing atmosphere and cooled to below 300 degrees in a direct air atmosphere and an oxidizing atmosphere, the finished product is reddish brown. After being added to clinker and ground into cement, it will affect the color of the cement.

[0003] Therefore, a calcination solution is needed that meets the requirements of calcination in a reducing atmosphere, high fuel burnout rate, and indirect heat exchange when cooling to below 300 degrees. However, existing clay calcination systems have problems such as calcination in an oxidizing atmosphere, low fuel burnout rate, difficult color control, and low heat recovery rate. Technical Solutions

[0004] In view of this, the object of the present invention is to provide an efficient clay suspension calcination system with controllable product color to solve the above problems.

[0005] Based on the above objectives, the present invention provides a high-efficiency clay suspension calcination system with controllable product color, comprising: a first-stage cyclone, a second-stage cyclone, a third-stage cyclone, a carbon monoxide elimination chamber, a main combustion chamber, a first-stage heat exchanger, a heat recovery system and a suspension cooling system; a first gas channel is connected between the top of the first-stage cyclone and the top of the second-stage cyclone, and a clay feeding port is provided on the first gas channel; a carbon monoxide elimination chamber is connected between the top of the second-stage cyclone and the top of the third-stage cyclone, and material discharged from the bottom of the first-stage cyclone is fed into the bottom of the carbon monoxide elimination chamber; material discharged from the bottom of the second-stage cyclone is fed into the main combustion chamber, the outlet of the main combustion chamber is connected to the inlet of the third-stage cyclone, and material discharged from the bottom of the third-stage cyclone is fed into the feed port at the top of the first-stage heat exchanger; the first-stage heat exchanger is connected to the heat recovery system, and the bottom of the first-stage heat exchanger is connected to the suspension cooling system; a second gas channel is connected between the heat recovery system and the main combustion chamber, and a third gas channel is connected between the heat recovery system and the suspension cooling system. Beneficial effects

[0006] Compared with the prior art, the present invention offers the following advantages: It utilizes a separate airflow control concept for combustion atmosphere control. By providing a carbon monoxide elimination chamber, it reduces the need for subsequent carbon monoxide elimination equipment and fuel consumption, thereby reducing investment and fuel consumption. Furthermore, by controlling the main clay combustion chamber to a reducing atmosphere, the color of the clay product is effectively controlled. After calcination, the high-temperature clay first enters the first-stage heat exchanger, where indirect heat exchange reduces the calcined clay temperature to below 300°C. The heat transfer oil, heated after the first-stage heat exchanger, then passes through the second and third-stage heat exchangers for heat recovery. The second-stage heat exchanger raises the temperature of the air entering the main combustion chamber and the carbon monoxide elimination chamber, improving fuel combustion efficiency. Thus, the present invention achieves both calcination in a reducing atmosphere and cooling to below 300°C through indirect heat exchange, while simultaneously achieving a high fuel burnout rate and fully recovering the heat from cooling the calcined clay. By utilizing a separate airflow control concept for combustion atmosphere control and providing a carbon monoxide elimination chamber, the present invention reduces the need for subsequent carbon monoxide elimination equipment and fuel consumption, thereby reducing investment and fuel consumption. At the same time, the main clay combustion chamber is controlled to maintain a reducing atmosphere, effectively controlling the color of the clay product. After calcination, the high-temperature clay first enters the first-stage heat exchanger, where indirect heat exchange reduces the temperature of the calcined clay to below 300°C. The thermal oil, heated after the first-stage heat exchanger, is then recycled through the second and third-stage heat exchangers. The second-stage heat exchanger raises the temperature of the air entering the main combustion chamber and the carbon monoxide elimination chamber, improving fuel combustion efficiency. Therefore, the present invention achieves the goal of calcining in a reducing atmosphere and cooling to below 300°C using indirect heat exchange, while simultaneously achieving a high fuel burnout rate and fully recovering the heat from cooling the calcined clay.

[0007] Furthermore, the heat recovery system includes a second-stage heat exchanger, a third-stage heat exchanger and a thermal oil storage tank. The thermal oil outlet of the first-stage heat exchanger is connected to the thermal oil inlet of the second-stage heat exchanger; the thermal oil outlet of the second-stage heat exchanger is connected to the thermal oil inlet of the third-stage heat exchanger, and the top outlet of the third-stage heat exchanger is connected to the first high-temperature gas channel. After heat exchange through the third-stage heat exchanger, the air enters the raw material drying and exhaust gas treatment system through the first high-temperature gas channel; the thermal oil outlet of the third-stage heat exchanger is connected to the inlet of the thermal oil storage tank, and the bottom outlet of the thermal oil storage tank is connected to the thermal oil inlet of the first-stage heat exchanger.

[0008] Furthermore, both ends of the second gas channel are connected to the top of the second-stage heat exchanger and the bottom of the main combustion chamber respectively. The second gas channel is connected to a first branch, and the end of the first branch is connected to the carbon monoxide elimination chamber.

[0009] Furthermore, the suspension cooling system includes a fourth-stage cyclone and a fifth-stage cyclone, the third gas channel is connected between the bottom of the second-stage heat exchanger and the top of the fourth-stage cyclone, the third gas channel is connected to a second branch, and the end of the second branch is connected to the first high-temperature gas channel; a fourth gas channel is connected between the fourth-stage cyclone and the top of the fifth-stage cyclone, the bottom of the first-stage heat exchanger is connected to a first unloading channel, and the end of the first unloading channel is connected to the fourth gas channel; the second unloading channel is connected between the bottom of the fourth-stage cyclone and the top of the fifth-stage cyclone, the top of the fifth-stage cyclone is connected to the first normal temperature air channel, and the bottom of the fifth-stage cyclone is connected to the finished product conveying channel.

[0010] Furthermore, a second high-temperature gas channel is connected to the top of the first-stage cyclone, and an end of the second high-temperature gas channel is connected to the raw material drying and exhaust gas treatment system. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG1 is a schematic diagram of a high-efficiency clay suspension calcination system with controllable product color provided by an embodiment of the present invention.

[0012] The markings in the figure are: 1. First-stage cyclone; 2. Second-stage cyclone; 3. Third-stage cyclone; 4. Main combustion chamber; 5. Carbon monoxide elimination chamber; 6. First-stage heat exchanger; 7. Second-stage heat exchanger; 8. Third-stage heat exchanger; 9. Thermal oil storage tank; 10. Fourth-stage cyclone; 11. Fifth-stage cyclone; 12. Heat recovery system; 13. Suspension cooling system. Modes for Carrying Out the Invention

[0013] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0014] As shown in Figure 1, the present invention proposes a high-efficiency clay suspension calcination system with controllable product color. The system comprises a first-stage cyclone 1, a second-stage cyclone 2, a third-stage cyclone 3, a carbon monoxide elimination chamber 5, a main combustion chamber 4, a first-stage heat exchanger 6, a heat recovery system 12, and a suspension cooling system 13. The first-stage cyclone 1 utilizes a high-efficiency, dust-collecting dual cyclone. A second high-temperature gas channel is connected to the top of the first-stage cyclone 1. The high-temperature flue gas in the second high-temperature gas channel is used to dry the raw materials. A first gas channel is connected between the inlet of the first-stage cyclone 1 and the outlet of the second-stage cyclone 2. A raw material feed point is provided on the first gas channel.

[0015] A carbon monoxide removal chamber 5 is connected between the inlet of the second-stage cyclone 2 and the outlet of the third-stage cyclone 3. A fifth discharge channel is connected between the carbon monoxide removal chamber 5 and the bottom of the first-stage cyclone 1. The carbon monoxide removal chamber 5 is a pipe-type structure, with the end of the fifth discharge channel connected to the end of the carbon monoxide removal chamber 5 near the third-stage cyclone 3. The installation of the carbon monoxide removal chamber 5 reduces the need for subsequent carbon monoxide removal equipment and fuel consumption, reducing investment and lowering fuel consumption.

[0016] A sixth discharge channel connects the bottom of the second-stage cyclone 2 to the lower portion of the main combustion chamber 4. A fifth gas channel and a third discharge channel connect the top of the main combustion chamber 4 to the third-stage cyclone 3, respectively. A fourth discharge channel connects the bottom of the third-stage cyclone 3 to the top of the first-stage heat exchanger 6. The first-stage heat exchanger 6 is connected to the heat recovery system 12. A second gas channel connects the heat recovery system 12 to the main combustion chamber 4, and a third gas channel connects the heat recovery system 12 to the suspension cooling system 13.

[0017] The heat recovery system 12 consists of a second-stage heat exchanger 7, a third-stage heat exchanger 8, and a thermal oil storage tank 9. The top of the first-stage heat exchanger 6 is connected to the top of the second-stage heat exchanger 7, the bottom of the second-stage heat exchanger 7 is connected to the top of the third-stage heat exchanger 8, the bottom of the third-stage heat exchanger 8 is connected to the top of the thermal oil storage tank 9, and the bottom of the thermal oil storage tank 9 is connected to the bottom of the first-stage heat exchanger 6. A second gas channel is connected between the top of the second-stage heat exchanger 7 and the bottom of the main combustion chamber 4. A first branch is connected to the second gas channel, the end of which is connected to the carbon monoxide elimination chamber 5. A second normal-temperature air channel is connected to the bottom of the third-stage heat exchanger 8, and a first high-temperature gas channel is connected to the top of the third-stage heat exchanger 8. The high-temperature flue gas in the first high-temperature gas channel is used to dry the raw materials.

[0018] After calcining, the high-temperature clay is cooled to below 300°C via indirect heat exchange in the first-stage heat exchanger 6. Thermal oil is used as the heat transfer medium, transferring heat from the high-temperature calcined clay to the oil in the first-stage heat exchanger 6, creating conditions for heat recovery. The heated oil then enters the second-stage heat exchanger 7, where it exchanges heat with air exhausted from the suspension cooling system 13 through the third gas channel, raising the air temperature again and recovering heat. The heat-exchanged oil then enters the third-stage heat exchanger 8 for heat recovery, exchanging heat with ambient-temperature air entering the third-stage heat exchanger 8 to generate high-temperature air for drying the raw materials.

[0019] The suspension cooling system 13 consists of a fourth-stage cyclone 10 and a fifth-stage cyclone 11. The third gas channel connects between the bottom inlet of the second-stage heat exchanger 7 and the top outlet of the fourth-stage cyclone 10. A second branch is connected to the third gas channel, the end of which is connected to the first high-temperature gas channel. A fourth gas channel connects between the inlet of the fourth-stage cyclone 10 and the top outlet of the fifth-stage cyclone 11. A first discharge channel is connected to the bottom outlet of the first-stage heat exchanger 6, the end of which is connected to the fourth gas channel. A second discharge channel connects between the bottom of the fourth-stage cyclone 10 and the top of the fifth-stage cyclone 11. The top of the fifth-stage cyclone 11 is connected to the first normal-temperature air channel, and the bottom of the fifth-stage cyclone 11 is connected to the finished product conveying channel.

[0020] Usage process: Step 1: Feed the raw material into the first gas channel, where the material undergoes heat exchange and enters the second-stage cyclone 2 along with the gas, and the material is discharged from the discharge port of the second-stage cyclone 2.

[0021] Step 2: The discharged material enters the main combustion chamber 4, which is calcined under a reducing atmosphere, where the clay is activated. After calcination and activation, the clay is gray.

[0022] Step 3: The calcined and activated clay enters the third-stage cyclone 3 and is discharged from its discharge port. The flue gas is discharged from the top outlet of the third-stage cyclone 3 and enters the carbon monoxide elimination chamber 5.

[0023] Step 4: Most of the hot air from the second-stage heat exchanger 7 enters the main combustion chamber 4. The excess air coefficient in this chamber is controlled to be less than 1, and the fuel burns in a slightly oxygen-deficient state, keeping the clay calcined in a reducing atmosphere. A small portion also enters the carbon monoxide elimination chamber 5, where it eliminates CO from the flue gas exiting the third-stage cyclone 3 in an oxygen atmosphere. A certain amount of hot air is added to the bottom of the carbon monoxide elimination chamber 5, so that the flue gas entering the carbon monoxide elimination chamber 5 has an oxidizing atmosphere and an excess air coefficient greater than 1.15. CO is eliminated at a high temperature of approximately 800°C, ensuring complete fuel combustion and reducing system heat consumption.

[0024] Step 5: The hot calcined clay discharged from the third-stage cyclone 3 enters the first-stage heat exchanger 6. This heat exchanger uses indirect heat transfer, using thermal oil as the heat transfer medium. This process cools the calcined clay from 800°C to below 300°C in a non-oxidizing atmosphere. Magnetite is gray and unstable above 300°C. In an oxidizing atmosphere, it oxidizes to hematite and a reddish-brown color. Therefore, the indirect cooling process described above is required to achieve both cooling and color control.

[0025] Step 6: In the first-stage heat exchanger 6, heat is transferred from the high-temperature calcined clay to the heat transfer oil. The heat transfer oil enters the second-stage heat exchanger 7 and exchanges heat with the hot air at the outlet of the fourth-stage cyclone 10 again. The air temperature rises again, realizing heat recovery and improving the combustion efficiency of the calcination system.

[0026] Step 7: The heat transfer oil is recycled through the third-stage heat exchanger 8 for heat recovery. The heat heats the ambient temperature air, producing high-temperature air, which is then used to dry the raw materials. The heat transfer oil is then recycled through the thermal oil storage tank 9 to the first-stage heat exchanger 6 for the next cycle.

[0027] Step 8: The calcined clay, cooled by the first-stage heat exchanger 6, enters the fourth gas channel, where it continues to exchange heat and cool. It then enters the fourth-stage cyclone 10 along with the air. The cooled calcined clay is collected and discharged from the lower discharge port of the fourth-stage cyclone. Part of the heat-exchanged air enters the second-stage heat exchanger 7 for further heating, while the remaining air enters the raw material drying system, where it is combined with the high-temperature exhaust gas from the first-stage cyclone 1 to dry the raw materials.

[0028] Step 9: The calcined clay discharged from the lower part of the fourth-stage cyclone 10 after cooling enters the second discharge channel, where it undergoes further heat exchange cooling and enters the fifth-stage cyclone 11 along with the air. The cooled calcined clay is collected and discharged from the lower discharge port of the fifth-stage cyclone 11, completing the final cooling and serving as the product discharge system.

[0029] Therefore, the present invention satisfies the requirements of calcination in a reducing atmosphere, heat exchange to below 300 degrees during indirect cooling, and further increases the hot air temperature under indirect heating, thereby recovering heat and improving combustion efficiency.

[0030] The embodiments of the present invention are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An efficient clay suspension calcination system with controllable product color, comprising: A first-stage cyclone, a second-stage cyclone, a third-stage cyclone, a carbon monoxide elimination chamber, a main combustion chamber, a first-stage heat exchanger, a heat recovery system and a suspension cooling system; characterized in that: A first gas channel is connected between the top of the first-stage cyclone and the top of the second-stage cyclone, and a clay feeding port is arranged on the first gas channel; a carbon monoxide elimination chamber is connected between the top of the second-stage cyclone and the top of the third-stage cyclone, and the material discharged from the bottom of the first-stage cyclone is fed into the bottom of the carbon monoxide elimination chamber; the material discharged from the bottom of the second-stage cyclone is fed into the main combustion chamber, the outlet of the main combustion chamber is connected to the inlet of the third-stage cyclone, and the material discharged from the bottom of the third-stage cyclone is fed into the top feed port of the first-stage heat exchanger; the first-stage heat exchanger is connected to the heat recovery system, and the bottom of the first-stage heat exchanger is connected to the suspension cooling system; a second gas channel is connected between the heat recovery system and the main combustion chamber, and a third gas channel is connected between the heat recovery system and the suspension cooling system.

2. The high-efficiency clay suspension calcination system with controllable product color according to claim 1, characterized in that: The heat recovery system includes a second-stage heat exchanger, a third-stage heat exchanger and a heat transfer oil storage tank. The heat transfer oil outlet of the first-stage heat exchanger is connected to the heat transfer oil inlet of the second-stage heat exchanger; the heat transfer oil outlet of the second-stage heat exchanger is connected to the heat transfer oil inlet of the third-stage heat exchanger, and the top outlet of the third-stage heat exchanger is connected to the first high-temperature gas channel. After heat exchange through the third-stage heat exchanger, the air enters the raw material drying and exhaust gas treatment system through the first high-temperature gas channel; the heat transfer oil outlet of the third-stage heat exchanger is connected to the inlet of the heat transfer oil storage tank, and the bottom outlet of the heat transfer oil storage tank is connected to the heat transfer oil inlet of the first-stage heat exchanger.

3. The high-efficiency clay suspension calcination system with controllable product color according to claim 2, characterized in that: The two ends of the second gas channel are respectively connected to the top of the second-stage heat exchanger and the bottom of the main combustion chamber. The second gas channel is connected to a first branch, and the end of the first branch is connected to the carbon monoxide elimination chamber.

4. The high-efficiency clay suspension calcination system with controllable product color according to claim 2, characterized in that: The suspension cooling system includes a fourth-stage cyclone and a fifth-stage cyclone, a third gas channel is connected between the bottom of the second-stage heat exchanger and the top of the fourth-stage cyclone, a second branch is connected to the third gas channel, and an end of the second branch is connected to the first high-temperature gas channel; a fourth gas channel is connected between the fourth-stage cyclone and the top of the fifth-stage cyclone, a first unloading channel is connected to the bottom of the first-stage heat exchanger, and an end of the first unloading channel is connected to the fourth gas channel; a second unloading channel is connected between the bottom of the fourth-stage cyclone and the top of the fifth-stage cyclone, a first normal-temperature air channel is connected to the top of the fifth-stage cyclone, and a finished product conveying channel is connected to the bottom of the fifth-stage cyclone.

5. The high-efficiency clay suspension calcination system with controllable product color according to claim 2, characterized in that: The top of the first-stage cyclone is connected with a second high-temperature gas channel, and the end of the second high-temperature gas channel is connected with a raw material drying and waste gas treatment system.

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