CN111692877A - Flue gas utilization system, flue gas utilization process and high-temperature combustion treatment system - Google Patents

Abstract

The invention relates to a flue gas utilization system, a flue gas utilization process and a high-temperature combustion treatment system. The flue gas utilization system is applied to a high-temperature combustion treatment system. The high-temperature combustion treatment system includes a combustion chamber and a rotary kiln, and the combustion chamber is provided with a natural gas burner And the air distribution device, the flue gas utilization system includes: flue gas settling device, exhaust flue, high temperature induced draft fan, outlet flue, return flue and return fan, wherein the return flue is communicated with the flue gas settling device and is set in the combustion chamber. The return fan on the chamber introduces part of the flue gas from the flue gas settling device into the combustion chamber of the high temperature combustion treatment system to burn the combustible volatiles in the flue gas to generate heat. The flue gas utilization system of the invention can effectively solve the problems of high energy consumption of the existing rotary kiln, continuous provision of heat source by the combustion chamber, insufficient combustion of the flue gas in the incineration chamber, ineffective utilization of the flue gas, and difficulty in igniting the flue gas entering the combustion chamber. , and can be applied to the carbonization process of activated carbon to produce activated carbon.

Description

Flue gas utilization system, flue gas utilization process and high temperature combustion treatment system

technical field

The invention belongs to the field of flue gas utilization, and in particular relates to a flue gas utilization system, a flue gas utilization process and a high-temperature combustion treatment system.

Background technique

In the field of coal-based activated carbon production technology, the flue gas generated in the traditional rotary kiln contains a lot of combustible volatiles. The heat generated by incineration in the incinerator enters the waste heat boiler for work recovery, and then is treated by the denitration system and the desulfurization and dust removal system before being discharged.

The incinerator in the prior art has huge volume, long flue gas retention time, and cannot guarantee complete combustion. In addition, an economizer or a cooling device is usually added at the tail of the waste heat boiler to perform heat exchange, recover flue gas waste heat and reduce flue gas temperature. However, due to the large amount of combustible volatiles in the flue gas, it is easy to cause blockage and corrosion of the heat exchanger tube bundle, resulting in shortened service life of the heat exchanger, resulting in disorder of the process system, frequent shutdown of the kiln to repair the equipment, and incomplete combustion of smoke. The volatiles in the gas accumulate in the pipeline or the dust removal system, which will not only block the pipeline and equipment, but also cause fire in the rotary kiln exhaust gas treatment system, which may cause the safety hazard of dust removal, fire or explosion.

On the other hand, the high-temperature combustion treatment system needs to continuously supplement the heat source in the combustion chamber of the kiln head. The fuel is generally coal-fired, or the combustion of natural gas with methane as the main component is used to provide heat. The demand for fuel is large and the cost increases. Frequent coal filling is not conducive to environmental preservation, the process fluctuates greatly, and there are many safety hazards.

From the above, the prior art mainly has the following disadvantages: the combustion chamber of the high temperature combustion treatment system needs to continuously provide new heat sources, which increases energy consumption, increases costs, poses great safety hazards, and is difficult to manage. In addition, the incineration chamber occupies a large area, the volatiles in the flue gas cannot be completely burned in the incineration chamber, and the temperature is not easy to control.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the above problems, provide a flue gas utilization system, a flue gas utilization process and a high-temperature combustion treatment system, so as to solve the need for continuous addition of heat sources to the combustion chamber of the high-temperature combustion treatment system, high system energy consumption, and combustion of flue gas in the incineration room. Insufficient and optimized overall flue gas treatment equipment layout and other issues.

In order to achieve the above object, the present invention provides a flue gas utilization system, which is applied to a high-temperature combustion treatment system. The high-temperature combustion treatment system includes a combustion chamber and a rotary kiln. The combustion chamber is provided with a natural gas burner and an air distribution device. It is characterized in that, the flue gas utilization system includes:

The flue gas settling device is arranged at the feed end of the rotary kiln;

The discharge flue is arranged at the outlet end of the flue gas settling device;

The high-temperature induced draft fan is connected to the exhaust flue, and is used to form a negative pressure inside the high-temperature combustion treatment system;

The outlet flue is connected to the high-temperature induced draft fan for exhausting flue gas;

return to the flue, and communicate with the flue gas settling device; and

A return fan is arranged on the combustion chamber and is used for introducing the flue gas in the flue gas settling device into the combustion chamber from the return flue.

According to an aspect of the present invention, the flue gas settling device is provided with a sliding ash slope and an ash accumulation tank located under the sliding ash slope.

According to one aspect of the present invention, the return flue is a hollow heat preservation channel.

According to one aspect of the present invention, the return flue is a pipeline containing thermal insulation or refractory thermal insulation material, or a regenerative pipeline built with refractory bricks inside and wrapped with thermal insulation or thermal insulation material on the outside.

According to one aspect of the present invention, the height of the return flue is 1.2-1.5m, the width is 0.6-0.8m, the top of the return flue is arched, the bend is arcuate, and refractory bricks are built inside.

According to one aspect of the present invention, the return flue is an underground flue.

According to one aspect of the present invention, the flue gas settling device comprises a settling chamber, an incineration chamber and a waste heat boiler connected in sequence;

The sliding ash slope is arranged in the settling chamber, and the return flue is communicated with the settling chamber.

According to one aspect of the present invention, the settling chamber, the incineration chamber and the waste heat boiler of the flue gas settling device are of an integrated structure, and the interior is built with refractory bricks.

According to one aspect of the present invention, the incineration chamber is used to combust the combustible volatiles in the flue gas.

According to one aspect of the present invention, the waste heat boiler is used for recovering the waste heat in the flue gas to perform work and generate steam.

According to one aspect of the present invention, refractory checker bricks are built inside the combustion chamber for storing thermal energy to ignite the combustible volatiles introduced into the flue gas.

According to one aspect of the present invention, the return fan is a high-flow and low-pressure high-temperature-resistant fan.

According to one aspect of the present invention, the rotary kiln is provided with temperature measuring points at the kiln head, in the kiln and at the kiln tail respectively.

According to one aspect of the present invention, the high temperature induced draft fan forms a negative pressure inside the flue gas settling device.

According to one aspect of the present invention, the internal negative pressure of the high temperature combustion treatment system and the flue gas settling device is -10 to -100Pa.

According to an aspect of the present invention, the return fan controls the negative pressure at the exit of the return flue to be between -10 and -20Pa.

According to an aspect of the present invention, a temperature maintaining device is further provided at the return fan.

According to one aspect of the present invention, the temperature maintenance device is a jacket of superheated steam surrounding a thermal insulating material.

According to one aspect of the present invention, the ratio of the return of flue gas is controlled by adjusting the frequency of the return fan.

According to an aspect of the present invention, the proportion of the flue gas returned to the combustion chamber from the return flue in the total flue gas generation amount is 1/3-1/2.

According to one aspect of the present invention, the temperature of the return flue gas is maintained above 350°C.

According to one aspect of the present invention, the steam provides heat to keep the return fan warm.

The present invention also provides a flue gas utilization process utilizing the above-mentioned flue gas utilization system, including:

Step S1, turning on the high-temperature induced draft fan to form a negative pressure in the high-temperature combustion processing system, and opening the natural gas burner in the combustion chamber to ignite the gas to heat the high-temperature combustion processing system;

Step S2, start feeding when the temperature of the kiln tail of the rotary kiln rises to a predetermined temperature, and the material is heated in the rotary kiln to generate flue gas;

Step S3, the flue gas enters the flue gas settling device, and the flue gas is filtered and dedusted;

Step S4, turning on the return fan to lead part of the filtered and dedusted flue gas back to the combustion chamber for combustion through the return flue.

According to an aspect of the present invention, in the step S4, the frequency of the return fan is adjusted to ensure that the rotary kiln maintains the process temperature:

When the temperature of the rotary kiln reaches the process temperature requirement, the air distribution device is adjusted to reduce the air distribution, and the natural gas burner is closed to reduce the gas input;

When the temperature of the rotary kiln is lower than the process temperature requirement, the air distribution device is adjusted to increase the air distribution, and the natural gas burner is opened to increase the gas input.

According to one aspect of the present invention, the high-temperature induced draft fan forms a negative pressure of -10 to -100 Pa inside the high-temperature combustion treatment system.

According to an aspect of the present invention, the return fan is turned on to control the negative pressure at the exit of the return flue to be between -10 and -20Pa.

According to an aspect of the present invention, in the step S2, the predetermined temperature at the end of the kiln when the rotary kiln starts charging is set to be 200-400°C.

According to one aspect of the present invention, the other part of the flue gas after filtering and dedusting first enters the incineration chamber to be incinerated to generate heat, and then enters the waste heat boiler to do work to generate steam. The incoming high temperature fan is sent to the subsequent flue gas purification system from the outlet flue.

According to one aspect of the present invention, the process temperature is 180 to 850°C.

According to one aspect of the present invention, the flue gas utilization process is used for the carbonization process of activated carbon.

According to one aspect of the present invention, there is provided a high temperature combustion treatment system, comprising:

A combustion chamber, which is provided with a natural gas burner and an air distribution device;

a rotary kiln, which is connected to the combustion chamber and receives the heat provided by the combustion chamber to heat and process the materials entering the rotary kiln;

A flue gas utilization system as described in any of the above; and

The flue gas purification system is used for purifying the flue gas discharged from the outlet flue of the flue gas utilization system.

According to one aspect of the present invention, the purification treatment of the flue gas includes desulfurization and denitration treatment of the flue gas.

The flue gas utilization system and process of the present invention form a stable airflow inside the high temperature combustion treatment system, reduce the amount of air entering, prevent the ignition phenomenon in the rotary kiln in the high temperature combustion treatment system, stabilize the process and improve the product quality. At the same time, there is no need to frequently add fuel, which improves the on-site operating environment, greatly saves costs, and eliminates potential safety hazards.

With the flue gas utilization system and process of the invention, part of the high-temperature flue gas in the incineration chamber is led back to the combustion chamber for combustion through the return fan, the work of the flue gas recycling reduces the burden of the incineration chamber, the incineration is sufficient, and the volume of the incineration chamber can be greatly increased. It is beneficial to make the spatial structure layout more reasonable.

The flue gas utilization system and process of the present invention filter the flue gas through the sliding ash slope, set the return flue as an underground flue, use a high-flow and low-pressure return fan, and set a temperature maintenance device to maintain the flue gas temperature. The way of building refractory checkered bricks indoors is conducive to the ignition of the flue gas in the combustion chamber. The structure of the return flue and the interior of the combustion chamber is designed. The mutual combination of the above settings enables the flue gas to be fully burned in the combustion chamber, avoiding the need for flue gas. Into the combustion chamber can not be ignited or the combustion is unstable and insufficient.

Compared with the structure in the prior art in which the combustion chamber is connected with the mixing chamber and then connected to the rotary kiln, the flue gas utilization system of the present invention cancels the setting of the mixing chamber, so that the combustion chamber is directly connected with the kiln head of the rotary kiln, The system structure is optimized, and the negative pressure loss is small, which is conducive to more direct and efficient heat transfer.

Description of drawings

Fig. 1 schematically shows the structure diagram of the flue gas utilization system according to the present invention;

Figure 2 schematically represents a cross-sectional view of the flue gas return flue according to the present invention;

Figure 3 schematically represents a combustion chamber and an internal view of the incineration chamber according to the invention;

Figure 4 schematically represents a flow chart of a flue gas utilization process according to the invention.

Detailed ways

In order to more clearly describe the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

When describing embodiments of the present invention, the terms "portrait", "landscape", "top", "bottom", "front", "rear", "left", "right", "vertical", " The orientation or positional relationship expressed by "horizontal", "top", "bottom", "inside" and "outside" is based on the orientation or positional relationship shown in the relevant drawings, which are only for the convenience of describing the present invention and simplifying the description, and It is not intended to indicate or imply that the referred device or element must have a particular orientation, be constructed and operate in a particular orientation, and thus the above terms should not be construed as limiting the invention.

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments cannot be repeated here, but the embodiments of the present invention are not limited to the following embodiments.

As shown in FIG. 1 , the flue gas utilization system of the present invention is applied to a high-temperature combustion treatment system. The high-temperature combustion treatment system includes a combustion chamber 1 and a rotary kiln 2. The combustion chamber 1 is provided with a natural gas burner 11 and an air distribution system. The flue gas utilization system includes: a flue gas settling device 3, which is arranged at the feed end of the rotary kiln 2; a discharge flue 6, which is arranged at the outlet end of the flue gas settling device 3; a high-temperature induced draft fan 7, and a discharge flue 6 is connected to form a negative pressure inside the high-temperature combustion treatment system; the outlet flue 8 is communicated with the high-temperature induced draft fan 7 to discharge the flue gas; the return flue 9 is communicated with the flue gas settling device 3; the return fan 10, It is arranged on the combustion chamber 1 and is used to introduce part of the flue gas in the flue gas settling device 3 into the combustion chamber 1 through the return flue 9 to burn the combustible volatiles in the flue gas to generate heat. The high-temperature combustion treatment system of the present invention further includes a flue gas purification system for purifying the flue gas discharged from the flue gas outlet flue 8 of the flue gas utilization system.

Compared with the structure in which the combustion chamber is connected to the mixing chamber and then connected to the rotary kiln in the prior art, the flue gas utilization system of the present invention cancels the setting of the mixing chamber, so that the combustion chamber 1 is directly connected to the kiln in the rotary kiln 2 The head-to-head connection optimizes the structure of the high-temperature combustion treatment system, and the negative pressure loss is small, which is conducive to more direct and efficient heat transfer.

As shown in Figure 1, the flue gas settling device 3 of the present invention comprises a settling chamber 3a, an incineration chamber 4 and a waste heat boiler 5 that are connected in sequence, and the settling chamber 3a, the incineration chamber 4 and the waste heat boiler 5 have an integrated structure, and in the settling chamber 3a A sliding ash slope 31 is provided, the lower end of the sliding ash slope 31 protrudes out of the flue gas settling device 3, and an ash accumulation groove 32 is arranged below the sliding ash slope 31, and the return flue 9 communicates with the settling chamber 3a. The flue gas settling device 3 of the present invention is provided with a sliding ash slope 31, which can well filter the dust in the flue gas, so that when the flue gas enters the incineration chamber 4 and enters the combustion chamber 1 from the return flue 9 for combustion Can burn more fully.

1 and 2, according to an embodiment of the present invention, the return flue 9 is a hollow thermal insulation channel, which can be set as a pipeline containing thermal insulation or refractory thermal insulation materials, or is built with refractory bricks inside and wrapped outside Regenerative piping of thermal insulation or thermal insulation material. According to the second embodiment of the present invention, the return flue 9 is an underground flue, that is, a part of the return flue 9 is arranged underground. In this embodiment, the height of the return flue 9 is 1.2-1.5m, the width is 0.6-0.8m, the top of the return flue 9 is set in an arched structure, and the bend is set as an arc. The arch design at the top of the return flue 9 and the arc arrangement at the elbow of the present invention optimize the structure of the return flue 9, which is beneficial to reduce the return resistance of the flue gas. Setting the return flue 9 as an underground flue is conducive to maintaining the temperature of the flue gas in the return flue 9, reducing the heat loss when the flue gas enters the combustion chamber, so that the flue gas can be easily ignited in the combustion chamber, At the same time, the tar light components in the flue gas are prevented from being deposited on the flue wall due to condensation due to temperature reduction, and the flue is blocked.

As shown in FIG. 3 , according to an embodiment of the present invention, the combustion chamber 1 of the present invention is built with refractory lattice bricks, and the number and arrangement of the refractory lattice bricks can be determined according to the size of the rotary kiln 2 and the combustion chamber 1 . Since the combustion chamber 1 is built with a refractory lattice brick structure, by controlling the number and spacing of the lattices and the staggered or parallel arrangement, the control of the flow rate of the flue gas entering the combustion chamber 1 can be realized, which is beneficial to control the combustion time. The flue gas is fully contacted with the high-temperature refractory checkered bricks, so as to ignite the combustible volatiles in the flue gas and provide heat for the rotary kiln. In addition, in the present invention, the settling chamber 3a, the incineration chamber 4 and the waste heat boiler 5 of the flue gas settling device 3 are of an integrated structure, the interior is built with refractory bricks, the exterior is covered with ordinary red bricks, and the middle is filled with thermal insulation materials.

In the present invention, a return fan 10 is provided between the return flue 9 and the combustion chamber 1 in order to ensure that the flue gas is introduced back into the combustion chamber 1 for smooth combustion. In the present invention, the return fan 10 is set as a high-flow and low-pressure high-temperature-resistant fan, and the negative pressure at the outlet 10 of the return flue is controlled to be -10 to -20Pa, so that the flow rate of the flue gas toward the combustion chamber can be controlled to avoid smoke Excessive air flow rate is not conducive to the ignition in the combustion chamber 1, or the combustion is insufficient.

In addition, in the present invention, the return fan 10 is also provided with a temperature maintenance device for maintaining the temperature of the flue gas entering the return fan, which is equivalent to thermally insulating the flue gas before the flue gas enters the combustion chamber 1, which is more beneficial to Ignition with smoke. At the same time, it can prevent the coal tar light components in the flue gas from condensing due to the decrease in temperature, which will block the fan.

4, according to the above-mentioned flue gas utilization system of the present invention, the present invention also provides a flue gas utilization process, including: S1, turning on the high-temperature induced draft fan 7 to form -10 inside the high-temperature combustion processing system and the flue gas settling device. When the negative pressure of -100Pa is reached, the combustion chamber 1 opens the natural gas burner 11 to ignite the gas to heat the high temperature combustion treatment system, so that the temperature of the combustion chamber 1 reaches 900-1050 ° C; S2, the temperature of the kiln tail of the rotary kiln 2 rises to 200 The material is fed at a predetermined temperature of -400 °C. After the material reaches the process temperature in the rotary kiln 2, flue gas is generated; S3. The flue gas enters the flue gas settling device 3, and the dust in the flue gas is deposited by the filtering action of the ash slope 31; S4. Turn on the return fan 10 to lead part of the filtered and dedusted flue gas back to the combustion chamber 1 through the return flue 9 for combustion. The other part of the filtered flue gas then enters the incineration chamber 4 for incineration to generate heat and transfer it to the waste heat boiler to do work, generate steam through heat exchange, and after heat exchange, the temperature of the flue gas is reduced to below 150 ℃ and enters the high temperature induced draft fan through the exhaust flue 6 7 is sent to the subsequent flue gas purification system from the outlet flue 8.

In step S4, adjusting the frequency of the return blower 10 can ensure that the rotary kiln 2 maintains the process temperature: when the temperature of the rotary kiln 2 reaches the process temperature requirement, adjust the air distribution device to reduce air distribution, and close the natural gas burner 11 to reduce gas input; When the temperature of the rotary kiln 2 is lower than the process temperature requirement, the air distribution device is adjusted to increase air distribution, and the natural gas burner 11 is opened to increase the gas input.

Specifically, firstly, the high-temperature induced draft fan 7 is started to form a negative pressure of -10 to -100Pa in the high-temperature combustion treatment system, and the natural gas input at the natural gas burner 11 is ignited for system heating, and the refractory lattice bricks in the combustion chamber 1 are ignited. Heating to 900-1050°C, and keep the internal refractory checkered bricks in a state of red burning and heat storage. When the temperature of the kiln end of the rotary kiln 2 rises to about 200-400°C, the material is fed. By adjusting the speed of the kiln, the air distribution and other measures , when the rotary kiln reaches the process temperature of 180-850 ℃, the flue gas containing combustible volatiles is produced. The flue gas passes through the flue gas settling device 3 in turn, the ash slide 31 deposits the contained soot, and part of the filtered flue gas enters the incineration chamber 4 to burn the combustible volatiles in the flue gas, and the heat enters the waste heat boiler 5 to do work , steam is generated through heat exchange, and the temperature of the flue gas is reduced to below 150 ℃ through the exhaust flue 6 into the high-temperature induced draft fan 7, and then sent to the subsequent flue gas purification system through the exit flue 8. The flue gas purification system purifies the flue gas, including desulfurization and denitrification of the flue gas. When the temperature of the incineration chamber 4 reaches 850°C-900°C, the return fan 10 is turned on, the negative pressure at the exit of the return flue 9 is controlled between -10 and -20Pa, and the flue gas temperature is maintained at 350 through the return flue. Above ℃, the combustible volatiles in part of the flue gas drawn back from the flue gas settling device 3 are ignited in the combustion chamber 1 by the high-temperature refractory checkered bricks, releasing heat. The temperature of the return flue is related to the ignition point and the total amount of volatiles in the flue gas components. The volatile components in the flue gas include oxygen, hydrogen, carbon monoxide and methane. For example, when the ignition point of the volatiles is low and the total amount is large, The corresponding temperature will be higher. Therefore, the flue gas temperature can be controlled by controlling the amount of flue gas entering the return flue. At the same time, if the process temperature is low, in order to ensure that the temperature of the generated flue gas in the return flue can reach above 350°C, the temperature of the flue gas can be increased before entering the return flue. The frequency of the return fan 10 is adjusted from low to high, and the matching is adjusted at any time according to the process temperature change. When the temperature of the rotary kiln reaches the process temperature requirement, the natural gas is turned off and the air distribution is reduced to realize the recycling of the flue gas. When the temperature of the rotary kiln 2 is lower than the process temperature requirement When the air distribution device is adjusted, the air distribution device is increased, and the natural gas burner 11 is opened, and the amount of flue gas generated in the system can be adjusted by the feeding amount or adjusting the process temperature. In the high-temperature combustion treatment system of the present invention, temperature measuring points are respectively set at the kiln head, the kiln and the kiln tail of the rotary kiln 2 .

Part of the flue gas enters the incineration chamber 4 and the heat generated by incineration enters the waste heat boiler 5 to do work, and the steam generated by heat exchange can be used to provide heat for the return fan 10 to keep warm.

The flue gas utilization system and process of the invention utilizes a part of the flue gas, so that the amount of flue gas in the incineration chamber is reduced, and the combustion is more complete, without worrying about incomplete combustion of the flue gas, blockage of the system, burning of the dust collector and substandard discharge. , so that the feed amount (output) of the rotary kiln can be increased to achieve the purpose of increasing production.

The flue gas utilization system and process of the invention can form a stable airflow inside the system, reduce the amount of air and gas input, prevent the phenomenon of fire in the kiln, stabilize the process, improve the product quality, reduce the energy consumption of the system, and reduce the energy consumption of the system. product cost. At the same time, there is no need to frequently add fuel, which improves the on-site environment, greatly saves costs, and eliminates potential safety hazards.

The flue gas utilization system and process of the present invention diverts the flue gas generated by the rotary kiln of the high-temperature combustion treatment system, reduces the amount of high-temperature flue gas entering the incineration chamber, and guides part of the high-temperature flue gas back to the combustion chamber for combustion through the return fan. Through the flue gas recycling, the burden of the incineration chamber is reduced, the incineration is sufficient, and the volume of the incineration chamber can be greatly reduced, which is conducive to a more reasonable layout of the internal space structure of the flue gas settling device.

The flue gas utilization system and process of the present invention maintains the flue gas temperature by filtering the flue gas, setting the return flue as an underground flue, using a high-flow and low-pressure return blower, and setting a temperature maintaining device to maintain the flue gas temperature, and build a stack in the combustion chamber. The ways of building refractory checkered bricks are all conducive to the ignition of the flue gas in the combustion chamber. The combination of the above settings enables the flue gas to be fully burned in the combustion chamber, and avoids the inability of the flue gas to enter the combustion chamber and cannot be ignited or the combustion is unstable and insufficient. disadvantages.

The flue gas utilization system and flue gas utilization process of the present invention can be used in the carbonization process of activated carbon, and can of course also be applied in other processes and systems and sections where other materials can generate combustible volatile flue gas after high temperature treatment.

The above description is only one embodiment of the present invention, and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (30)

1. The utility model provides a flue gas utilizes system, is applied to on the high temperature combustion processing system, and this high temperature combustion processing system includes combustion chamber (1) and rotary kiln (2), and this combustion chamber (1) is equipped with natural gas nozzle (11) and air distribution device, and its characterized in that, this flue gas utilizes system to include:

the flue gas sedimentation device (3) is arranged at the feed end of the rotary kiln (2);

the discharge flue (6) is arranged at the outlet end of the flue gas sedimentation device (3);

the high-temperature induced draft fan (7) is connected with the exhaust flue (6) and is used for forming negative pressure inside the high-temperature combustion treatment system;

the outlet flue (8) is connected with the high-temperature induced draft fan (7) and is used for discharging flue gas;

the return flue (9) is communicated with the flue gas settling device (3); and

the return fan (10) is arranged on the combustion chamber (1) and is used for introducing the flue gas in the flue gas settling device (3) into the combustion chamber (1) through the return flue (9).

2. The flue gas utilization system according to claim 1, wherein the flue gas settling device (3) is provided with a dust slide slope (31) and an ash accumulation groove (32) positioned below the dust slide slope (31).

3. The flue gas utilization system according to claim 1, wherein the return flue (9) is a hollow insulating channel.

4. The flue gas utilization system according to claim 3, wherein the return flue (9) is a pipe containing heat insulating or fire-resistant insulating material, or a regenerative pipe internally constructed with refractory bricks and externally wrapped with heat insulating or insulating material.

5. The flue gas utilization system according to claim 1 or 3, wherein the height of the return flue (9) is 1.2-1.5m, the width is 0.6-0.8m, the top of the return flue (9) is arched, the bend is arc-shaped, and refractory bricks are built inside.

6. A flue gas utilization system according to claim 1 or 3, characterized in that the return flue (9) is an underground flue.

7. The flue gas utilization system according to claim 2, wherein the flue gas settling device (3) comprises a settling chamber (3a), an incineration chamber (4) and a waste heat boiler (5) connected in sequence;

the ash sliding slope (31) is arranged in the settling chamber (3a), and the return flue (9) is communicated with the settling chamber (3 a).

8. The flue gas utilization system according to claim 7, wherein the settling chamber (3a) of the flue gas settling device (3), the incineration chamber (4) and the waste heat boiler (5) are of an integrated structure, and the interior of the integrated structure is built by refractory bricks.

9. The flue gas utilization system according to claim 7 or 8, wherein the incineration chamber (4) is used for burning combustible volatiles in the flue gas.

10. The flue gas utilization system according to claim 9, wherein the exhaust heat boiler (5) is used for recovering the exhaust heat in the flue gas to do work and generate steam.

11. The flue gas utilization system according to claim 1, wherein the combustion chamber (1) is internally laid with refractory checker bricks for storing thermal energy to ignite the combustible volatiles introduced into the flue gas.

12. The flue gas utilization system of claim 1, wherein the return fan (10) is a high flow, low pressure, high temperature tolerant fan.

13. The flue gas utilization system according to claim 1, wherein temperature measuring points are respectively arranged at the head, the middle and the tail of the rotary kiln (2).

14. The flue gas utilization system of claim 1, wherein the negative pressure is from-10 to-100 Pa.

15. The flue gas utilization system according to claim 1, wherein the return fan (10) controls the negative pressure at the outlet of the return flue (9) between-10 and-20 Pa.

16. The flue gas utilization system according to claim 1, wherein a temperature maintaining device is further provided at the return fan (10).

17. The flue gas utilization system of claim 16, wherein the temperature maintenance device is a jacket of superheated steam wrapped around insulation material.

18. The flue gas utilization system of claim 1, wherein the ratio of flue gas return is controlled by adjusting the frequency of the return fan (10).

19. The flue gas utilization system according to claim 1 or 18, characterized in that the ratio of flue gas returned to the combustion chamber (1) by the return flue (9) in the total flue gas production is 1/3-1/2.

20. The flue gas utilization system according to claim 19, wherein the return flue (9) flue gas temperature is maintained above 350 ℃.

21. The flue gas utilization system of claim 10, wherein the steam provides heat to keep the return fan (10) warm.

22. A flue gas utilizing process using the flue gas utilizing system as claimed in any one of claims 1 to 21, comprising:

step S1, starting a high-temperature induced draft fan (7) to enable the high-temperature combustion processing system to form negative pressure, and opening a natural gas burner (11) in a combustion chamber (1) to ignite fuel gas to heat the high-temperature combustion processing system;

s2, starting feeding when the temperature of the kiln tail of the rotary kiln (2) rises to a preset temperature, heating the materials in the rotary kiln (2) and generating smoke;

step S3, enabling the flue gas to enter a flue gas settling device (3) for filtering and dedusting;

and step S4, starting a return fan (10) to guide part of the filtered and dedusted flue gas back to the combustion chamber (1) for combustion through a return flue (9).

23. The flue gas utilization process of claim 22, wherein in the step S4, the frequency of the return fan (10) is adjusted to ensure that the rotary kiln (2) maintains a process temperature of:

when the temperature of the rotary kiln (2) meets the process temperature requirement, the air distribution device is adjusted to reduce air distribution, and the natural gas burner (11) is closed to reduce gas input;

and when the temperature of the rotary kiln (2) is lower than the process temperature requirement, the air distribution device is adjusted to increase air distribution, and the natural gas burner (11) is opened to increase gas input.

24. The flue gas utilization process of claim 22, wherein the high-temperature induced draft fan (7) forms negative pressure of-10 to-100 Pa inside the high-temperature combustion treatment system.

25. The flue gas utilization process of claim 22, wherein the negative pressure at the outlet of the return flue (9) is controlled between-10 and-20 Pa by turning on the return fan (10).

26. The flue gas utilization process according to claim 22, wherein in the step S2, the predetermined kiln tail temperature at the beginning of charging the rotary kiln (2) is set to 200 to 400 ℃.

27. The flue gas utilization process of claim 22, wherein the other part of the filtered and dedusted flue gas enters the incineration chamber (4) to be incinerated to generate heat, then enters the waste heat boiler (5) to do work to generate steam, and enters the high temperature fan (7) through the exhaust flue (6) after the temperature of the flue gas is reduced to below 150 ℃ after heat exchange, and is sent to the subsequent flue gas purification system through the outlet flue (8).

28. The flue gas utilization process of claim 23, wherein the process temperature is 180 to 850 ℃.

29. The flue gas utilization process according to any one of claims 22 to 28, wherein the flue gas utilization process is used for a carbonization process treatment of activated carbon.

30. A high temperature combustion processing system, comprising:

the combustion chamber (1), the combustion chamber (1) is provided with a natural gas burner (11) and an air distribution device;

the rotary kiln (2) is connected with the combustion chamber (1), receives heat provided by the combustion chamber (1), and heats materials entering the rotary kiln (2);

a flue gas utilization system as claimed in any one of claims 1 to 21; and

and the flue gas purification system is used for purifying the flue gas discharged from the outlet flue (8) of the flue gas utilization system.

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