CN114674157A - Vertical annular preheating calcining kiln and rotary kiln calcining system for two-stage calcining - Google Patents

Abstract

This patent provides a vertical annular preheating calcining kiln, which has a secondary burner and is applied to the calcination of block and granular materials, so that the production capacity of the rotary kiln is greatly improved, the energy consumption of the product is greatly reduced, and the production of nitrogen oxides. It includes an outer casing, an inner casing, a material-bearing bottom plate, a casing enclosed by a closed connecting plate, and a discharging device; the bottom of the outer casing is connected to the material-bearing bottom plate, and the periphery of the closed connecting plate is connected to the inner casing; the outer casing and the inner casing are connected to the inner casing. The shell surrounds an annular cavity, and the top of the shell has a feed channel and an exhaust gas discharge channel that communicate with the annular cavity; the center of the material-bearing bottom plate is provided with an air inlet, which is also a discharge port; the driving mechanism of the discharge device Installed outside the outer shell, the actuator of the unloading device extends into the kiln cavity between the top of the material-bearing bottom plate and the lower end of the inner shell, and the outlet of the secondary burner arranged on the shell is communicated with the kiln cavity, and the secondary combustion The inlet of the device is connected to the fuel source or/and the high temperature gas source.

Description

Vertical annular preheating calcining kiln and two-stage calcining rotary kiln calcining system

technical field

This patent relates to a vertical preheater and a rotary kiln calcination system with a vertical preheater.

Background technique

Rotary kilns are widely used in cement, metallurgy, and chemical industries to calcine materials, with a history of more than 130 years. The feed end of the rotary kiln is higher and the discharge end is lower. The fuel is injected into the kiln from the discharge end for combustion. The flue gas and the material flow in the opposite direction. At first, the exhaust gas was directly discharged into the atmosphere, which was a waste of energy. Later, a grate preheater, a cyclone preheater, etc. were invented. The waste heat of the rotary kiln exhaust gas was used to preheat the material, which reduced energy consumption and increased the output of the rotary kiln. Cement calcination, and later invented the calciner outside the kiln, the fuel required for the entire production system is not only injected from the discharge end of the rotary kiln, but also injected into the calciner as the second combustion zone for combustion. Part of it is decomposed, so that the process of decomposing limestone in the rotary kiln is completed before entering the rotary kiln, thereby greatly increasing the production capacity of the rotary kiln and further reducing the calcination heat consumption of cement clinker. The raw material for the production of cement clinker is powder.

Rotary kilns are especially used for the production of lime for lumpy materials. Although a vertical preheater with a pusher is widely used, there is no technology like the decomposition furnace type of cement production that removes the materials before entering the rotary kiln. The material is pre-calcined in the second combustion zone, so the heat consumption of the rotary kiln for calcining lime is high and the production capacity is low.

1. In the existing "preheater-rotary kiln-cooler" calcining block granular material system with material particle size ≥ 2mm, the fuel required by the entire system is all injected from the rotary kiln kiln head burner, and the function of the preheater The function is only to recycle the waste heat of the exhaust gas generated by the rotary kiln to a limited extent to heat the material.

Among the "preheater-rotary kiln-cooler", the heat transfer capacity and efficiency of the rotary kiln are the lowest, especially for the calcined block limestone, the output per unit volume of the rotary kiln is only less than 1.0t/d.m³, It is about 1/4 of the cement kiln. Due to the low output per unit volume, the heat loss of the equipment shell such as the rotary kiln per unit weight product is large. Therefore, how to play the role of a preheater with relatively high heat exchange efficiency is the working direction of energy saving and improving production capacity. The decomposition rate or pre-firing rate of the materials entering the kiln can greatly increase the output of the rotary kiln, but there is no report or actual use of the related technology. As far as the existing push-head vertical preheater is concerned, it is no longer possible to make the preheater undertake more thermal decomposition functions.

The commonly used pusher type vertical preheater has an inner and an outer cylinder structure. The material is placed in the annular space with a material support bottom formed by the inner and outer cylinders to form an annular material layer, which participates in heat exchange. The height of the material layer is generally about 2.0m. The flue gas discharged from the rotary kiln rises and enters the annular material layer for heat exchange. The heated material is pushed into the rotary kiln by the hydraulic pusher, and the exhaust gas is discharged from the top. According to the size of the rotary kiln, vertical preheaters of different specifications can be configured. Multiple or even more than ten pushers can be set around the outer cylinder, correspondingly divided into multiple or even more than ten material storage chambers, and the flue gas is carried out in the storage chamber. Heat exchange, the pusher pushes the material into the rotary kiln alternately, and the pusher moves back and forth.

Although this vertical preheater has a large size, the actual amount of material stored is not large, the resistance of the material layer and the entire system device is relatively large, the height of the material layer is relatively low, and the heat exchange time between the material and the flue gas is not sufficient. , the temperature of the exhaust gas is still relatively high, the utilization rate of heat energy is not high, and the material leakage caused by the reciprocating motion of the pusher, it is necessary to set up several collecting pipes and hoppers to undertake the leakage material, and then manually deal with these leakage materials, Obviously, the airtightness of the gas is not good, and more air leaks in, which causes the actual temperature of the heat exchange flue gas to drop.

2. A "preheater-rotary kiln-cooler" calcining block granular material system, especially suitable for ores with a material particle size of 15mm-40mm, such as limestone, dolomite, bauxite, pellets, metal ore, architectural ceramics Rotary kiln calcination system such as pellets has the characteristics of relatively uniform heating of materials and uniform quality of products leaving the kiln. Its production process line generally consists of raw material feeding system, preheater system, rotary kiln, cooler system, rotary kiln burner system, smoke The main equipments such as air induced draft fan are composed of cooler-rotary kiln-vertical preheater-dust collector-flue gas induced draft fan-chimney in series according to the gas flow direction; according to the material flow direction, raw material feeding system-preheater-high temperature material The feeding device-rotary kiln-cooler are connected in series in sequence; the axis of the rotary kiln cylinder is at an angle with the horizontal. Generally, the sine value sinɑ or the tangent value tanɑ of the angle is 3.5%, the feed end is high, the discharge end is low, and the fuel is automatically The discharge end of the rotary kiln is injected into the kiln for combustion. The main function of the preheater is to use the waste heat of the high-temperature flue gas to preheat the material, so that the temperature of the material is increased when entering the rotary kiln, reducing the heat load of the rotary kiln, and recovering part of the heat, which is a physical process; for calcined limestone/white cloud For calcined pellets, a grate preheater is generally used. For calcined ceramsite, a rotary preheater is generally used. There is no preheating device. The function of the rotary kiln is to calcine the material at a higher temperature than that in the preheater, and physical and chemical reactions occur to produce products; the main function of the cooler is to cool the products produced by the rotary kiln to facilitate transportation, Storage and recovery of heat is usually by air cooling. The air after heat exchange enters the rotary kiln to support combustion, and some also use rapid cooling to control the crystal form of calcined materials, such as direct pool bathing. However, it is known that the heat exchange efficiency of materials in the rotary kiln is low, the output per unit volume is low, the heat dissipation loss of the rotary kiln cylinder is large, the energy consumption per unit weight of the product is high, and the _NOx concentration in the flue gas produced by combustion is high, which exceeds the environmental protection control standard.

3. For a long time, the end of the rotary kiln kiln head is usually installed with a heat-resistant steel guard plate to prevent the refractory material from falling down and loose, but the actual application of the heat-resistant steel guard plate is prone to high temperature burning, flue gas corrosion, fracture and failure. Once the kiln mouth guard fails, it will cause damage to the kiln mouth cylinder, and the kiln mouth cylinder will turn into a trumpet shape, which will also affect the service life of the kiln mouth refractory bricks or refractory castables. Heat-resistant steel guards are often replaced within 2 years, and some even have a service life of only 2-3 months. A set of heat-resistant steel guards is tens of thousands of yuan for small kilns and 200,000 to 300,000 yuan for larger kilns. Production and maintenance are stopped. It takes time, and it is still difficult to overcome the deformation of the rotary kiln cylinder and the trumpet shape of the frying mouth. Due to the damage of the guard plate, the kiln head and kiln tail sealing devices connected to it will also fail, and there are often ash and air leakage.

In addition to limestone, other block and granular materials have similar heat exchange and movement conditions in the rotary kiln.

Therefore, how to increase the output per unit volume or the output per unit cross-sectional area of the rotary kiln is a key issue in reducing heat consumption.

4. In the preheater-rotary kiln-cooler block and granular material calcination system, due to the high flame temperature generated by the rotary kiln burner, a large amount of _NOx will be produced to pollute the atmospheric environment.

However, for the vertical preheater-rotary kiln-vertical cooler calcining system for calcining limestone, dolomite, etc., because most of the vertical preheaters of the sub-chamber pusher type are used, the connection between the preheater and the rotary kiln is - "Transfer chute", the flue gas is in the temperature range of 800-1050 ℃, but the channel is short and narrow, and the reducing agent and NO _X in the flue gas do not have enough space and time to fully complete the mixing and reduction reaction, and do not have the ability to install and reduce Therefore, the existing sub-chamber pusher vertical preheater-rotary kiln-vertical cooler calcination system for calcining limestone, dolomite, etc. does not have the conditions to use the SNCR process for denitrification. After the heat exchange is completed in the heater, the selective catalytic reduction technology is used for SCR denitration, and the temperature of the flue gas discharged needs to be controlled in an appropriate range, but the investment is large, the operating cost is high, and the enterprise is unbearable. Therefore, currently calcined limestone and dolomite , Bauxite and other industries have basically not used denitrification devices.

5. For the calcination of 2-15mm materials, especially the ultra-high temperature calcination, because the range of particle size is very "embarrassing", as a cyclone or suspension type preheater similar to a cement kiln, due to the too large particle size, it cannot be suspended. Unable to adapt; as a vertical preheater with push head similar to lime production, because the particles are too small and the resistance is too large, it cannot be adapted. For example, in limestone or dolomite mines, 2-15mm ore basically cannot be used for calcining lime.

For 2-15mm dolomite/magnesite ultra-high temperature magnesia-calcium sand, there is currently no preheater technology in the world, and the length of the rotary kiln can only be lengthened, which is 2-3 times longer than the length of the general rotary kiln with a preheater. , but the final exhaust temperature is still above 600 ℃, and the heat consumption is equivalent to 2-3 times that of the general light-burning dolomite. The higher the calcination temperature is, the more NO _X is produced in the flue gas, and the exhaust gas temperature is higher but lower than the SNCR denitration process.

The chain grate-rotary kiln used for iron-making pellets has a large system area, many supporting equipment, large investment, low thermal efficiency, high failure rate and high operating cost.

The ceramsite is calcined by a two-stage or three-stage rotary kiln, which has higher energy consumption.

SUMMARY OF THE INVENTION

The purpose of this patent is to provide a vertical annular preheating calcining kiln, which has a secondary burner, which is applied to the calcination of block and granular materials, especially the calcination of lime, so that the production capacity of the rotary kiln is greatly improved, The energy consumption of the product is greatly reduced and the production of nitrogen oxides is reduced.

In order to achieve the above purpose, the vertical annular preheating and calcining kiln of this patent includes an outer casing, an inner casing, a material-bearing bottom plate, a casing enclosed by a closed connecting plate, and a discharge device; the outer casing and the inner casing are erected. Polygonal or circular structure, the bottom of the outer casing is connected to the material-bearing bottom plate, the periphery of the closed connecting plate is connected to the inner casing and is higher than or equal to the lower end of the inner casing; the outer casing and the inner casing form an annular cavity, the casing The top has a feed channel and a tail gas discharge channel that communicate with the annular cavity; the center of the material-bearing bottom plate is provided with an air inlet, which is also a discharge port; the drive mechanism of the discharge device is installed outside the outer casing, and the discharge device executes The mechanism extends into the kiln cavity between the top of the material-bearing bottom plate and the lower end of the inner shell, and the material is fed into the annular cavity through the feeding channel and carried by the material-bearing bottom plate; In the kiln cavity, when the actuator of the unloading device acts, the material is discharged through the unloading port; the outlet of the secondary burner arranged on the shell is communicated with the kiln cavity, and the inlet of the secondary burner is connected with the fuel source or/and The high temperature gas source is connected.

The above-mentioned vertical annular preheating and calcining kiln has a secondary combustion chamber in the kiln cavity that materials cannot reach, and the outlet of the secondary combustion chamber is communicated with the secondary combustion chamber.

In the above-mentioned vertical annular preheating calcining kiln, a secondary combustion chamber is formed between the lower part of the closed connecting plate and the inner shell; the inner shell of the lower part of the closed connecting plate is a heat-resistant steel material or a hollow structure, and the inner shell of the hollow structure Internal ventilation or cooling medium cooling.

The secondary burner (or burner) is installed on the closed connecting plate, and the outlet of the secondary burner communicates with the secondary combustion chamber.

The combustion-supporting air is passed into the secondary combustion chamber through the pipeline or the combustion-supporting air passage in the burner, or the cooling air after cooling the inner shell of the hollow structure is passed into the secondary combustion chamber.

In the above-mentioned vertical annular preheating calcining kiln, material guide bridges are arranged at intervals along the circumferential direction in the annular cavity, and a secondary combustion chamber is formed below the material guide bridge.

In the annular cavity, a guide bridge is connected between the outer casing and the inner casing. The material above the guide bridge is blocked by the guide bridge and changes the direction of passage. It descends from both sides of the guide bridge. Between the material bridges are passages for the circulation of materials and airflow, the outlet of the secondary burner or/and the nozzle outlet of the denitrification device communicate with the secondary combustion chamber, and the secondary burner or/and the denitration device are installed in the vertical annular preheating calcination. on the kiln shell. The number of material guide bridges and secondary combustion chambers is set according to the size of the perimeter of the annular cavity.

In the above-mentioned vertical annular preheating calcination kiln, the combustion-supporting air is passed into the secondary combustion chamber through the secondary burner or an independent air passage.

The above-mentioned vertical annular preheating and calcining kiln is connected to the exhaust gas discharge channel at the top/upper part of the annular cavity near the outer shell side, and is connected to the feed channel near the inner shell side; the outlet height of the feed channel can be adjusted up and down or fixed.

In the above-mentioned vertical annular preheating and calcining kiln, the actuator of the unloading device is a pusher for reciprocating motion, or a screw blade or paddle for rotating motion, or a paddle for swing motion.

The patent also provides a rotary kiln calcining system with two stages of calcination, which reduces the amount of NOx generated, increases the output of the rotary kiln system, and consumes less energy.

The two-stage calcining rotary kiln calcining system described in this patent includes a rotary kiln system, a first-stage burner system, the vertical annular preheating calcining kiln, a cooler system, a raw material feeding system, a finished product discharging system, Tail gas treatment system; according to the material flow, the raw material feeding system, the vertical annular preheating calcining kiln, the rotary kiln system, the cooler system and the finished product discharge system are connected in series; according to the combustion gas flow, the primary burner system, the rotary kiln system, The vertical annular preheating calcination kiln and the tail gas treatment system are connected in series; the primary burner system provides heat source to the rotary kiln, and the fuel of the primary burner system is injected into the rotary kiln from the discharge end of the rotary kiln.

In the above-mentioned two-stage calcining rotary kiln calcination system, the discharge port of the vertical annular preheating and calcining kiln is connected with the feed port of the rotary kiln through a connecting channel, and the position of the discharge port of the vertical annular preheating and calcining kiln is higher than the feed port of the rotary kiln. , the flue gas generated by the rotary kiln enters the vertical annular preheating calcining kiln through the connecting channel for heat exchange with the material, and then enters the exhaust gas treatment system through the exhaust gas discharge channel. The exhaust gas treatment system has an induced draft fan; The feed channel at the top of the preheating calcination kiln is added to the annular cavity, and after heat exchange with the high temperature flue gas, the material is output to the discharge port by the unloading device and added to the rotary kiln through the connecting channel; The outlet of the stage burner communicates with the connecting channel.

The connecting channel is also called the transfer tank and the kiln tail smoke chamber. The high-temperature gas generated in the connecting channel enters the kiln cavity through the connecting channel for heat exchange with the material.

The above-mentioned two-stage calcining rotary kiln calcination system also includes a secondary combustion chamber, the gas outlet of the secondary combustion chamber is communicated with the connecting passage, and the outlet of the secondary combustion chamber is located in the secondary combustion chamber.

The high-temperature gas from the secondary burner enters the kiln cavity through the connecting channel for heat exchange with the material.

In the above-mentioned two-stage calcining rotary kiln calcination system, the temperature of the secondary combustion chamber is controlled at 800-1100°C, and the nozzle outlet of the SNCR denitration device is communicated with the secondary combustion chamber; or, the temperature of the connecting channel is controlled at 800-1100°C, The nozzle outlet of the SNCR denitration device communicates with the connecting channel.

Beneficial effects of this patent:

1. Compared with the preheater of the prior art, due to the establishment of the secondary calcination, the thermal process of the original block material preheater-rotary kiln-cooler calcination system has been greatly changed, and the secondary burner produces It increases the heat in the vertical annular preheating calcining kiln or/and increases the temperature in the vertical annular preheating calcining kiln, so that the material is partially calcined in the vertical annular preheating calcining kiln, which can increase the The amount of material entering the rotary kiln can greatly increase the output of the rotary kiln and the entire calcining system when the primary burner at the kiln head of the rotary kiln provides the same thermal intensity. A large amount of decomposition is carried out before the feeding port or/and in the vertical annular preheating calcining kiln, thereby increasing the capacity of the rotary kiln.

Due to the establishment of secondary calcination, the vertical annular preheating calcining kiln is a shaft furnace for calcining materials, or it is called a vertical annular preheating calcining furnace, and at the same time, it also uses the waste heat of the exhaust gas from the rotary kiln to preheat the material to save Energy, also a vertical preheater.

2. Since the heat exchange efficiency of the rotary kiln is lower than that of the vertical annular preheating calcining kiln, the heat dissipation loss of the rotary kiln is higher than that of the vertical annular preheating calcining kiln, and the thermal insulation performance of the vertical annular preheating calcining kiln is also better than that of the rotary kiln. The heat dissipation loss of thermal equipment such as kiln, vertical annular preheating calcining kiln, and rotary kiln is relatively fixed, and basically does not increase with the increase of output. Therefore, after increasing the output of the entire calcining system, the energy consumption of the product can be greatly reduced.

3. Due to the high flame temperature generated by the primary burner in the kiln head of the rotary kiln, the amount of thermal NOx generated is high, and the combustion environment of the secondary burner allows the flame temperature to be controlled in a relatively low range. The amount of thermal NOx produced is low, and therefore, the amount of NOx produced in the entire calcining system is greatly reduced.

4. Since the outlet height of the feed channel of the vertical annular preheating calcining kiln can be adjusted up and down or fixed, the height of the material layer in the kiln cavity can be adjusted and controlled, so as to adjust the resistance of the material layer to the gas. The annular preheating calcining kiln can adapt to materials of different particle sizes.

5. Compared with the traditional push-rod vertical preheater, the sealing performance of the vertical annular preheating calcining kiln is improved due to the use of a spiral discharge device, and there is no phenomenon of material stripping and air leakage.

6. Due to the location of the feed channel and the exhaust gas discharge channel of the vertical annular preheating calcining kiln, it is more conducive to the heat exchange effect between the high temperature gas and the material and the uniformity of heating, and it is beneficial to reduce the resistance of the material to the gas.

7. The investment and operation cost of the flue gas denitrification device of the production line can be reduced due to the nozzles of the denitrification device of the SNCR method arranged in the connecting channel or/and the secondary combustion chamber.

8. Due to the use of an annular sleeve type vertical cooler, the material is evenly distributed in the cooler, the resistance of the material to the cooling air is evenly distributed, the cooling air is evenly distributed in the cooler, and the effect of heat exchange between the cooling air and the material is even. , The flow of combustion-supporting air entering the rotary kiln is stable, which plays an important role in stabilizing the combustion in the rotary kiln.

9. Due to the establishment of secondary calcination, the thermal process of the original block material preheater-rotary kiln-cooler calcination system has been greatly improved. The calcination time in the rotary kiln can be shortened, so that the length of the rotary kiln can be shortened accordingly.

10. The present invention can also be used independently as a vertical annular calcining shaft kiln. When used independently as a vertical annular calcining shaft kiln, various forms of cooling devices can be connected under the discharge port to cool the calcined materials. The cooling device can be integrated with the vertical annular calcining shaft kiln. can be set separately. When used independently as a vertical annular calcining shaft kiln, there is no need to connect the rotary kiln calcining system.

Description of drawings

FIG. 1 is a schematic diagram of the rotary kiln calcination system for two-stage calcination in Example 1. FIG.

FIG. 2 is a top view of the second secondary burner and the nozzle of the denitrification device extending into the second secondary combustion chamber 2 in FIG. 1 .

3 is a schematic diagram of the vertical annular preheating calcining kiln of Example 2.

FIG. 4 is a top view of the second secondary burner and the nozzle of the denitrification device, etc., extending into the second secondary combustion chamber 2 in FIG. 3 .

5 is a schematic diagram of the vertical annular preheating calcining kiln of Example 3 and the like.

6 is a schematic diagram of the vertical annular preheating calcining kiln of Example 4 and the like.

7 is a schematic diagram of the vertical annular preheating calcining kiln of Example 5 and the like.

8 is a schematic diagram of the vertical annular preheating calcining kiln of Example 6 and the like.

9 is a schematic diagram of the vertical annular preheating calcining kiln of Example 7 and the like.

In the figure, the raw material feeding system 100, the rotary kiln system 200, the cooler system 300, the finished product discharge system 400, the primary burner system 500, the exhaust gas treatment system 600, the dust collector 601, the induced draft fan 602,

Vertical annular preheating and calcining kiln 1, annular cavity 11, feed channel 12, exhaust gas discharge channel 13, outer shell 15, inner shell 16, material bearing bottom plate 17, closed connecting plate 18, hollow structure 19,

Secondary combustion chamber 1 21, secondary combustion chamber 2 22, secondary combustion chamber 3 23, secondary combustor 1 24, secondary combustor 2 25, secondary combustor 3 26,

Unloading device 3, push head 31, helical blade 32,

The denitration device nozzle 4, the connecting channel 5, and the material guide bridge 6.

Detailed ways

Example 1:

Referring to the two-stage calcining rotary kiln calcination system shown in Figures 1 and 2, according to the material flow, the raw material feeding system 100, the vertical annular preheating calcining kiln 1, the rotary kiln system 200, the cooler system 300, and the finished product discharge system 400 They are connected in series in sequence; according to the combustion gas flow, the primary burner system 500 , the rotary kiln system 200 , the vertical annular preheating calcining kiln 1 , and the tail gas treatment system 600 are connected in series in sequence. The primary burner system provides heat source to the rotary kiln, and the fuel of the primary burner system is injected into the rotary kiln from the discharge end of the rotary kiln.

The discharge port of the vertical annular preheating and calcining kiln is connected with the feeding port of the rotary kiln through the connecting channel 5 (the connecting channel is also called the transfer tank and the kiln tail smoke chamber). The position of the discharge port of the vertical annular preheating and calcining kiln is higher than that of the rotary kiln At the feeding port, the flue gas generated by the rotary kiln enters the vertical annular preheating calcining kiln through this connecting channel to conduct heat exchange with the material, and then enters the exhaust gas treatment system through the exhaust gas discharge channel.

The vertical annular preheating and calcining kiln 1 includes an outer casing 15 , an inner casing 16 , a material-bearing bottom plate 17 , a casing enclosed by a closed connecting plate 18 , and a discharging device 3 . The outer casing and the inner casing are vertical polygonal or circular structures, the outer casing and the inner casing enclose an annular cavity 11, and the top of the casing has a feed channel 12 and an exhaust gas discharge channel 13 that communicate with the annular cavity. The exhaust gas discharge passage 13 is close to the outer casing side, and the feed passage 12 is close to the inner casing side. The outlet height of the feed channel can be adjusted up or down or fixed.

The bottom of the outer casing 15 is connected to the material-bearing bottom plate 17, and the center of the material-bearing bottom plate 17 is provided with an air inlet, which is also a discharge port.

The material is fed into the annular cavity 11 from the raw material feeding system 100 through the feed channel 12 at the top of the vertical annular preheating calcination kiln, and after heat exchange with the high-temperature flue gas, the material is output by the unloading device 3 to the discharge port through the connection The channel enters into the rotary kiln. The drive mechanism of the unloading device 3 is installed outside the outer shell, and the actuator of the unloading device extends into the kiln cavity between the upper part of the material-bearing bottom plate and the lower end of the inner shell, and the material is fed into the annular cavity through the feeding channel, and the material is fed into the annular cavity by the material-bearing The bottom plate is carried; when the actuator of the unloading device does not act, the material remains in the kiln cavity, and when the actuator of the unloading device acts, the material enters the feeding end of the rotary kiln through the discharge port and the connecting channel 5.

The periphery of the closed connecting plate 18 is connected to the upper end of the inner shell, or the closed connecting plate 18 is higher than the lower end of the inner shell 16 (see Figure 9), and a secondary combustion that cannot be reached by the material is formed between the lower part of the closed connecting plate and the inner shell. Room One 21. The second burner one (or burner one) 24 is mounted on the closed connecting plate 18 . The outlet of the secondary burner one is located in the secondary combustion chamber one.

The inner casing 16 which closes the lower part of the connecting plate has a hollow structure 19 which communicates with the atmosphere, and the inner casing of the hollow structure is ventilated or cooled by a cooling medium. The combustion-supporting air is passed into the second-stage combustion chamber 1 through the pipeline or the combustion-supporting air passage of the second-stage burner 1, or the cooling air after cooling the inner shell of the hollow structure is passed into the second-stage combustion chamber 1.

The outlet of the second stage burner 25 or/and the nozzle outlet of the denitrification device is communicated with the annular cavity 11, and the second stage burner or/and the nozzle 4 of the denitrification device are installed on the vertical annular preheating and calcining kiln shell. If the denitration device nozzle 4 is set on the shell of the vertical annular preheating calcination kiln, the temperature of the annular cavity 11 is controlled at 800-1100°C.

The gas outlet of the third-stage combustion chamber 23 communicates with the connecting passage 5, and the outlet of the third-stage combustion chamber 26 is located in the third-stage combustion chamber. The high-temperature gas from the secondary burner 326 enters the kiln cavity through the connecting channel for heat exchange with the material.

If the nozzle 4 of the SNCR denitration device is set on the connecting channel, the temperature of the connecting channel is controlled at 800-1100°C, and the nozzle outlet of the SNCR denitration device is located in the connecting channel.

The inlets of the first-stage burner 24, the second-stage burner 25, and the third-stage burner 26 are all connected to the fuel source or/and the high-temperature gas source.

Example 2:

Referring to the vertical annular preheating calcining kiln shown in Figures 3 and 4, the main difference from the vertical annular preheating calcining kiln in Example 1 is that a material guide bridge 6 is connected between the outer shell and the inner shell, and the material guides The bridges 6 are arranged at intervals along the circumferential direction of the annular cavity. The material above the guide bridge is blocked by the guide bridge and changes the direction of passage. It descends from both sides of the guide bridge, and the material and airflow are between the two adjacent guide bridges. A second-stage combustion chamber 22 is formed below the material guide bridge for the flow channel. The quantity of the material guide bridge and the second secondary combustion chamber is set according to the size of the perimeter of the annular cavity; The material guide bridge 6 may be composed of two upper and lower refractory plates with an air interlayer in the middle.

Example 3:

Referring to the vertical annular preheating calcining kiln shown in FIG. 5 , the main difference from the vertical annular preheating calcining kiln in Example 2 is that the closed connecting plate 18 is connected to the lower end of the inner shell, and the upper part of the closed connecting plate is connected to the inner shell. An opening is formed between the bodies to communicate with the atmosphere; the inner side of the inner casing 16 is protected by refractory materials; the embodiment 3 does not have the secondary combustion chamber 1 21 and the secondary burner 1 24 in the embodiment 2, which extend into the secondary combustion chamber. Parts such as the denitration device nozzle and the secondary burner 225 in the combustion chamber 222.

Example 4:

Referring to the vertical annular preheating calcining kiln shown in FIG. 6 , the main difference between it and the vertical annular preheating calcining kiln in Example 2 is that this Example 4 does not have the secondary combustion chamber 323 and the secondary combustion chamber in Example 2. The burner three 26, the nozzle of the denitrification device extending into the connecting channel, the nozzle of the denitration device extending into the secondary combustion chamber two, and the secondary burner two 25 and other components.

Example 5:

Referring to the vertical annular preheating calcining kiln shown in FIG. 7 , the main difference between it and the vertical annular preheating calcining kiln in Example 3 is that this Example 5 does not have the secondary combustion chamber 3 23 and the secondary combustion chamber in Example 3. The third burner 26, the nozzle of the denitrification device extending into the connecting channel, however, the nozzle 4 of the denitration device and the second two-stage burner 25, which extend into the second-stage combustion chamber 22, are added.

Example 6:

Referring to the vertical annular preheating calcining kiln shown in FIG. 8 , the main difference from the vertical annular preheating calcining kiln in Example 5 is that this Example 6 does not have the material guide bridge 6 in Example 5, and the denitration device nozzle 4 The outlet and the outlet of the second stage burner 25 are directly communicated with the annular cavity 11 .

Example 7:

Referring to the vertical annular preheating calcining kiln shown in FIG. 9 , the main difference from the vertical annular preheating calcining kiln in Example 2 is that the closed connecting plate 18 is higher than the lower end of the inner shell 16 .

In each embodiment, the actuator of the unloading device 3 is a push head 31 that performs reciprocating motion, or the actuator of the unloading device is a screw blade 32 or a paddle that performs rotary motion or swing motion.

Beneficial effects of this technology:

1 Compared with the preheater in the prior art, due to the establishment of the secondary calcination, the heat generated by the secondary burner increases the temperature, so that the material is partially calcined in the vertical annular preheating calcining kiln, thereby increasing the intake The amount of material in the rotary kiln; for example, the carbonate of limestone can be decomposed in a large amount at a temperature above 900 ℃, and the output of the rotary kiln and system can be greatly increased when the primary burner of the rotary kiln kiln provides the same thermal intensity.

2 Because the heat exchange efficiency of the rotary kiln is lower than that of the vertical annular preheating calcining kiln, the heat dissipation loss of the rotary kiln cylinder is higher than that of the vertical annular preheating calcining kiln, and the thermal insulation performance of the vertical annular preheating calcining kiln is higher than that of the rotary kiln. The heat dissipation loss of the vertical annular preheating calcining kiln, rotary kiln and other thermal equipment cylinders is relatively fixed and does not increase with the increase of output. Therefore, the energy consumption can be greatly reduced after the system output is increased.

3. Due to the high flame temperature generated by the primary burner at the kiln head of the rotary kiln, the amount of thermal NOx generated is high, and the combustion environment where the secondary burner is located enables the flame temperature to be controlled in a relatively low range, resulting in The amount of thermal NOx is low, therefore, the amount of NOx generated in the entire calcination system is greatly reduced.

4. Compared with the traditional push-rod vertical preheater, the sealing performance of the vertical annular preheating calcining kiln is improved due to the adoption of a screw or paddle-type unloading device, and there is no phenomenon of material stripping and air leakage.

Claims (10)

1. The vertical annular preheating calcining kiln includes an outer casing, an inner casing, a material-bearing bottom plate, a casing enclosed by a closed connecting plate, and a discharge device; it is characterized in that: the outer casing and the inner casing are vertical polygons or A circular structure, the bottom of the outer shell is connected to the material-bearing bottom plate, the periphery of the closed connecting plate is connected to the inner shell and is higher than or equal to the lower end of the inner shell; the outer shell and the inner shell form an annular cavity, and the top of the shell has The feed channel and exhaust gas discharge channel communicated with the annular cavity; the center of the material-bearing bottom plate is provided with an air inlet, which is also a discharge port; the drive mechanism of the discharge device is installed outside the outer casing, and the actuator of the discharge device extends. The material is fed into the kiln cavity between the upper part of the material-bearing bottom plate and the lower end of the inner shell, and the material is fed into the annular cavity through the feeding channel and carried by the material-bearing bottom plate; when the actuator of the unloading device does not act, the material remains in the kiln cavity In the body, when the actuator of the unloading device acts, the material is discharged through the discharge port; the outlet of the secondary burner arranged on the shell is communicated with the kiln cavity, and the inlet of the secondary burner is connected with the fuel source or/and high temperature gas source connected. 2 . The vertical annular preheating calcining kiln according to claim 1 , wherein the kiln cavity has a secondary combustion chamber that cannot be reached by materials, and the outlet of the secondary burner communicates with the secondary combustion chamber. 3 . 3. The vertical annular preheating calcining kiln according to claim 2, characterized in that: a secondary combustion chamber is formed between the lower part of the closed connecting plate and the inner shell; the inner shell of the lower part of the closed connecting plate is a heat-resistant steel material Or a hollow structure, the inner casing of the hollow structure is ventilated or cooled by a cooling medium. 4. The vertical annular preheating and calcining kiln according to claim 2, characterized in that: material guide bridges are arranged at intervals along the circumferential direction in the annular cavity, and a secondary combustion chamber is formed below the material guide bridge. 5. The vertical annular preheating and calcining kiln according to claim 1, characterized in that: the top/upper part of the annular cavity is connected to a tail gas discharge channel near the side of the outer shell, and is connected to a feed channel near the side of the inner shell; The outlet height of the material channel can be adjusted up and down or fixed. 6. The vertical annular preheating calcining kiln according to claim 1, wherein the actuator of the unloading device is a pusher for reciprocating motion, or a screw blade or paddle for rotating motion, or a swing motion. of the paddle. 7. The rotary kiln calcining system of two-stage calcination is characterized in that, it comprises rotary kiln system, one-stage burner system, vertical annular preheating calcining kiln described in claim 1, cooler system, raw material feeding system, finished product Unloading system and exhaust gas treatment system; according to the material flow, the raw material feeding system, vertical annular preheating calcining kiln, rotary kiln system, cooler system and finished product unloading system are connected in series; according to the combustion gas flow, the primary burner system, The rotary kiln system, the vertical annular preheating calcination kiln and the tail gas treatment system are connected in series in sequence; the primary burner system provides heat source to the rotary kiln, and the fuel of the primary burner system is injected into the rotary kiln from the discharge end of the rotary kiln. 8. The rotary kiln calcining system for two-stage calcining as claimed in claim 7, wherein the vertical annular preheating calcining kiln discharge port and the rotary kiln feeding port are connected through a connecting channel, and the vertical annular preheating calcining kiln is connected by a connecting channel. The discharge port is located higher than the feed port of the rotary kiln. The flue gas generated by the rotary kiln enters the vertical annular preheating calcining kiln through this connecting channel to conduct heat exchange with the material, and then enters the exhaust gas treatment system through the exhaust gas discharge channel. Fan; the material is fed from the raw material feeding system into the annular cavity through the feed channel at the top of the vertical annular preheating calcination kiln, and after heat exchange with the high temperature flue gas, the material is output by the unloading device to the discharge port and added to the discharge port through the connecting channel. In the rotary kiln; the outlet of the secondary burner arranged on the connecting passage communicates with the connecting passage. 9. The rotary kiln calcining system of two-stage calcining as claimed in claim 8, characterized in that, it also comprises a secondary combustion chamber, the gas outlet of the secondary combustion chamber is communicated with the connecting passage, and the outlet of the secondary burner is located in the second combustion chamber. Class combustion chamber. 10. The rotary kiln calcination system for two-stage calcination according to claim 7, characterized in that: the temperature of the secondary combustion chamber is controlled at 800-1100°C, and the nozzle outlet of the SNCR denitration device is communicated with the secondary combustion chamber; The temperature of the SNCR denitrification device is controlled at 800-1100 ° C, and the nozzle outlet of the SNCR denitrification device is communicated with the connecting channel.

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