CN116105492B

CN116105492B - Carbon capture auxiliary system for cement production line and CO2 sealing method

Info

Publication number: CN116105492B
Application number: CN202310387409.2A
Authority: CN
Inventors: 张超; 郑现明; 邓玉华; 王彬; 陶瑛; 姚秀丽; 李润国; 王国民; 孙学成
Original assignee: Cbmi Construction Co ltd
Current assignee: Cbmi Construction Co ltd
Priority date: 2023-04-12
Filing date: 2023-04-12
Publication date: 2023-06-16
Anticipated expiration: 2043-04-12
Also published as: WO2024041244A1; CN116105492A; ZA202308102B

Abstract

The invention relates to the technical field of cement production industry, in particular to a carbon capture auxiliary system for a cement production line and a CO2 sealing method, which comprise a sealing gas pipe network, wherein CO2 gas is input to an input end of the sealing gas pipe network, a first branch pipe, a second branch pipe and a third branch pipe are arranged at an output end of the sealing gas pipe network, and a pipe orifice of the first branch pipe is communicated with a kiln head sealing point and a kiln tail sealing point; the pipe orifice of the second branch pipe is communicated with the gate valve sealing point; the pipe orifice of the third branch pipe is communicated with a raw material feeding sealing point, an ash discharging opening sealing point and a dust collector discharging sealing point; pressure sensors are arranged in the sealing points, and regulating fans are arranged in the first branch pipe, the second branch pipe and the third branch pipe; the controller is electrically connected with the regulating fan and the pressure sensor; the sealing structure is arranged at the air leakage point, CO2 is filled into the sealing structure to form a CO2 gas insulating layer, the air leakage point of the equipment easy to leak air is changed into CO2 gas from air, and the air leakage is reduced.

Description

Carbon capture auxiliary system for cement production line and CO2 sealing method

Technical Field

The invention relates to the technical field of cement production industry, in particular to a carbon capture auxiliary system for a cement production line and a CO2 sealing method.

Background

The cement kiln firing system is generally adopted in the current cement production process, and specifically consists of a grate cooler, a burner, a rotary kiln, a preheater, a connecting air pipe and the like; wherein, the raw meal is preheated in a preheater and heated, then decomposed in a decomposing furnace, the decomposed hot raw meal is sent to a rotary kiln for calcination and is converted into cement clinker, then the cement clinker is sent to a grate cooler for cooling, and high-temperature air generated by the grate cooler is sent back to the preheater for recycling until the cement clinker production is completed.

Along with cement clinker production, a large amount of CO2 can be generated by the system, and at present, the cement industry usually adopts a cement kiln total oxygen combustion technology for CO2 treatment and a technology for capturing CO2 after coupling combustion; the method for capturing CO2 after combustion refers to the steps of purifying and capturing CO2 after the water of the flue gas after combustion is removed through a condensing tower, and the captured high-concentration CO2 is sent to a CO2 storage point for reuse, so that the technology generally has the problems of low CO2 gas capturing efficiency, high system investment and high operation cost; the total oxygen combustion means that oxygen with the concentration of more than 95% is utilized to replace air for supporting combustion, which is beneficial to improving the concentration of CO2 at the tail of a kiln, thereby saving the investment cost and the operation cost of a subsequent CO2 purification and trapping system.

Prior art 1: the application number is CN201310164913.2, and the CO2 concentration is up to 95% or more by adopting a cement production method that combines cement raw material pre-decomposition and conventional air combustion to perform clinker firing by adopting total oxygen to replace conventional air combustion in a decomposing furnace; prior art 2: a method for capturing CO2 gas generated by decomposing cement raw material, a cement production method and a system thereof, wherein the method comprises the steps of supplying cement raw material and CO2 carrier gas to an isolated decomposition chamber from the top and the bottom of the isolated decomposition chamber respectively during production so as to decompose the cement raw material; discharging CO2 gas generated by decomposing the cement raw meal together with CO2 carrier gas from the top of the isolated decomposition chamber; then capturing the discharged CO2 gas; so as to realize the high-efficiency and low-cost capturing and recycling of CO2 in the cement production process.

In the prior art, although the concentration of CO2 in the tail end of a production line is increased by capturing and circulating CO2 to participate in production, the influence of easy air leakage points in a cement system on the whole production link is not considered, if the air leakage amount in the system is increased, air leaked in from the air leakage points also participates in the oxy-fuel combustion reaction together, the concentration of CO2 in the tail end of a subsequent kiln is greatly reduced, and therefore, the influence of a sealing technology on the concentration of CO2 is important.

Prior art 3: the rotary kiln sealing device with the application number of CN201710575135.4 comprises a sealing cover, a plurality of fin plates, a tensioning steel wire rope, a plurality of steel wire rope positioning hooks and two counterweights, wherein the fin plates are conveniently installed by designing the sealing table into a circular truncated cone structure, and the fin plates are fixed along the width direction of the sealing table, so that the fin plates are tightly attached to the sealing cover, the resistance is reduced, and the good sealing effect of the sealing device is ensured; the rotary kiln solves the problem that air leaks in when the rotary kiln cylinder rotates, but the temperature of a sealing part is high when the rotary kiln operates, and the rotary kiln cylinder rotates along with the swing and the axial movement, so that the air leaks into the rotary kiln when the cylinder swings and the axial movement. Meanwhile, the gate valve is usually sealed by a packing pressurization cover on the contact side of the lifting rod and the upper valve body and on the contact side of the valve plate and the lower valve body, but in actual production, the valve body of the gate valve is subjected to internal air flow and pressure difference on two sides of the valve plate, the valve plate can shake, gaps are formed between the valve plate and the lower valve body and between the lifting rod and the upper valve body, and external air can enter the system from the gaps. Meanwhile, as the single rotary blanking device is generally adopted at the blanking point of each device, air can be poured into the system along the gap between the rotor blade and the shell of the rotary blanking device due to the fact that the outlet pressure of the rotary blanking device is smaller than the inlet pressure.

Therefore, in the prior art, air can enter a production system through each easy air leakage point to participate in cement preparation, and a large amount of air can be filled in the full-oxygen combustion production process at the moment, so that the concentration of CO2 gas at the tail end is greatly reduced, the application of a CO2 circulating system (used as cooling air of a grate cooler, mixed air of a main burner and the like) is not facilitated, and the cost of CO2 trapping and purifying is greatly increased.

Disclosure of Invention

The invention aims to solve the problems, so as to provide the carbon capture auxiliary system for the cement production line and the CO2 sealing method, which can effectively improve the concentration of CO2 at the kiln tail and save the investment cost and the operation cost of the CO2 purification and capture system.

The invention solves the problems, adopts a carbon capture auxiliary system, and specifically comprises the following steps:

the carbon trapping auxiliary system for the cement production line comprises a kiln head sealing point and a kiln tail sealing point of a rotary kiln, wherein the kiln head and the kiln tail of the rotary kiln are respectively provided with a gate valve sealing point, a raw material discharging opening of a preheater is provided with a raw material feeding sealing point, an ash discharging opening of a waste heat utilization device is provided with an ash discharging opening sealing point, and a discharging opening of a dust collector is provided with a dust collector discharging sealing point; the device comprises a sealing gas pipe network, wherein CO2 gas dehydrated by a condensing tower is input to an input end of the sealing gas pipe network, a first branch pipe, a second branch pipe and a third branch pipe are arranged at an output end of the sealing gas pipe network, two first branch pipes are arranged, and pipe orifices of the two first branch pipes are respectively communicated to a kiln head sealing point and a kiln tail sealing point; the pipe orifice of the second branch pipe is communicated with the gate valve sealing point; the third branch pipes are provided with three pipe orifices which are respectively communicated with a raw material feeding sealing point, an ash discharging opening sealing point and a dust collector discharging sealing point; pressure sensors are arranged in the kiln head sealing point, the kiln tail sealing point, the gate valve sealing point, the raw material feeding sealing point, the ash discharge opening sealing point and the dust collector discharging sealing point, and regulating fans are arranged in the first branch pipe, the second branch pipe and the third branch pipe; the air conditioner further comprises a controller, and the controller is electrically connected with the regulating fan and the pressure sensor.

Compared with the prior art, the invention adopting the technical scheme has the outstanding characteristics that:

through setting up seal structure in the air leakage point of easy air leakage equipment in cement manufacture system, fill CO2 gas and form CO2 gas isolation layer, leak into the air leakage point of easy air leakage equipment and cement kiln calcination and flue gas treatment system's gas and change from air into CO2 flue gas to reach the purpose that reduces the air leakage and go into, improved kiln tail CO2 concentration, and then improved CO2 gas entrapment efficiency, reduced CO2 entrapment system's system investment and running cost.

Preferably, the invention further adopts the technical scheme that:

the sealing structures at the kiln head sealing point and the kiln tail sealing point are that a rotary cover body is arranged at the kiln head and the kiln tail of the rotary kiln, and the rotary cover body is connected with a fixed cover body through a filler sealing device; a static friction ring cover body is additionally arranged between the rotary cover body and the fixed cover body, the static friction ring cover body is fixedly connected with the fixed cover body through a bracket, and the static friction ring cover body is in sliding sealing connection with the rotary cover body through a dynamic friction ring and a static friction ring; the pressure sensor is arranged in the static friction ring cover body, a first vent hole is formed in the static friction ring cover body, and the output end of the first branch pipe is connected to the first vent hole.

The gate valve sealing point is structured that a lifting rod of the gate valve is sealed with an upper valve body, a valve plate is sealed with a lower valve body by a gland, an outer cover body is arranged on the upper valve body of the gate valve, a second ventilation hole is arranged on the outer cover body, and the output end of the second branch pipe is connected to the second ventilation hole.

The raw material feeding sealing point, the ash discharging opening sealing point and the dust collector discharging sealing point all adopt a double-rotation blanking device structure, and the double-rotation blanking device comprises a first blanking device connected with a raw material discharging opening of a preheater, an ash discharging opening of a waste heat utilization device or a blanking opening of the dust collector, a blanking pipe is connected below the first blanking device, a second blanking device is connected with the lower end of the blanking pipe, a third air vent is formed in the blanking pipe, and the output end of a third branch pipe is connected to the third air vent.

The controller is electrically connected with the motor of the first blanking device and the motor of the second blanking device; the first blanking device and the second blanking device are controlled to be opened and closed so as to control blanking quantity and prevent material blockage.

The invention also provides a CO2 sealing method for the cement production line, which is carried out by using the carbon capture auxiliary system for the cement production line, and comprises the following specific steps:

s1: the cement production system operates in a total oxygen mode, and CO2 smoke is discharged from the outlet of the preheater;

s2: the CO2 flue gas is subjected to waste heat utilization through a waste heat boiler, then enters a bag type dust collector through a high-temperature fan, and the CO2 flue gas subjected to dust removal through the bag type dust collector enters a condensing tower to remove water;

s3: one part of the CO2 flue gas after water removal is conveyed to an input end of a sealing gas pipe network, and the other part of the CO2 flue gas is conveyed to a CO2 storage point for storage;

s4: CO2 flue gas is sent to a kiln head sealing point, a kiln tail sealing point, a gate valve sealing point, a raw material feeding sealing point, an ash discharge opening sealing point and a dust collector discharging sealing point through a sealing gas pipe network, and a CO2 isolation layer is formed at the kiln head sealing point, the kiln tail sealing point, the gate valve sealing point, the raw material feeding sealing point, the ash discharge opening sealing point and the dust collector discharging sealing point;

s5: the pressure sensor monitors the pressure in the first branch pipe, the second branch pipe and the third branch pipe, the gas pressure is fed back to the controller, the controller controls the rotation speed of the regulating fan in the first branch pipe, the second branch pipe and the third branch pipe by comparing the actual numerical value monitored by the comparison pressure sensor with a preset pressure threshold value so as to regulate and control the pressure in the kiln head sealing point, the kiln tail sealing point, the flashboard valve sealing point, the raw material feeding sealing point, the ash discharge sealing point and the dust collector discharging sealing point.

Further, in step S3, a part of the dehydrated CO2 flue gas is delivered to the CO2 capturing system, the CO2 flue gas purified by the CO2 capturing system is delivered to the input end of the sealed gas pipe network, and the other part is delivered to the CO2 storage point for storage.

Further, the concentration of CO2 gas conveyed into the sealing gas pipe network is not less than 70%.

Drawings

FIG. 1 is a schematic diagram of a layout structure of a carbon capture auxiliary system according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of another embodiment of a layout structure of a carbon capture assist system;

FIG. 3 is a schematic diagram of a kiln head or tail structure of a rotary kiln in an embodiment of the invention;

FIG. 4 is a schematic cross-sectional view of the structure at A-A in FIG. 3;

FIG. 5 is a schematic side view of a static friction ring cover according to an embodiment of the present invention;

FIG. 6 shows an embodiment of the present invention a gate valve sealing point structure schematic diagram;

FIG. 7 is a schematic diagram of a sealing point structure between a gate and a lower valve body of a gate valve according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of the seal points between the lifting rod and the upper valve body in an embodiment of the invention;

FIG. 9 is a schematic diagram of a structure of a double-rotary feeder according to an embodiment of the present invention.

In the figure: 1. a preheater; 2. a decomposer; 3. a rotary kiln; 4. a grate cooler; 5. a waste heat utilization device; 6. a dust collector; 7. a condensing tower; 8. a CO2 capture system; 9. a CO2 recycling system; 10. sealing a gas pipe network; 11. a CO2 storage point; 12. kiln head sealing points; 13. kiln tail sealing points; 14. a gate valve sealing point; 15. feeding raw materials into a sealing point; 16. an ash discharge port sealing point; 17. a dust collector discharging sealing point; 18. a static friction ring cover; 1801. a first vent hole; 1802. a dust discharging hole cover; 19. a bracket; 20. a tensioning device; 21. a static friction ring a; 22. a dynamic friction ring a; 23. a rotary cover body; 24. a rotary cylinder; 25. fish scale steel sheet; 26. a spacer ring; 27. a brush; 28. a packing seal a; 29. a packing seal b; 30. a pressure adjusting device; 31. a static friction ring b; 32. a dynamic friction ring b; 33. fixing the cover body; 34. a ventilation hole a; 35. a ventilation hole b; 36. a ventilation hole c; 37. a third branch pipe; 38. a lifting rod; 39. an upper valve body; 40. a lower valve body; 41. a housing body; 42. a valve plate; 43. a second branch pipe; 44. a gland; 45. packing; 46. a first blanking device; 47. a second blanking device; 48. and (5) blanking pipes.

Detailed Description

The invention is further described below in connection with the following examples which are provided for the purpose of better understanding of the present invention and are, therefore, not to be construed as limiting the scope of the invention.

On the basis of a raw cement production system, the embodiment provides a carbon trapping auxiliary system for a cement production line, as shown in fig. 1 and 2, wherein the raw cement production system comprises a preheater 1, a decomposer 2, a rotary kiln 3, a grate cooler 4, a waste heat utilization device 5, a dust collector 6, a condensing tower 7, a CO2 trapping system 8, a CO2 circulating system 9 and a CO2 storage point 11, kiln heads and kiln tails of the rotary kiln 3 are respectively provided with a kiln head sealing point 12 and a kiln tail sealing point 13, a gate valve is provided with a gate valve sealing point 14, a raw material feed opening of the preheater 1 is provided with a raw material feed sealing point 15, an ash discharge opening sealing point 16 is arranged at an ash discharge opening of the waste heat utilization device 5, and a dust collector discharge sealing point 17 is arranged at a feed opening of the dust collector 6; as shown in fig. 1 to 9, the carbon capture auxiliary system provided in this embodiment specifically includes a sealing gas pipe network 10, and CO2 tail gas generated by a cement production system is dehydrated by a condensation tower 7 and then is input to an input end of the sealing gas pipe network 10, and an output end of the sealing gas pipe network 10 is provided with a first branch pipe, a second branch pipe 43 and a third branch pipe 37; the two first branch pipes are arranged, and the pipe orifices of the two first branch pipes are respectively communicated to the kiln head sealing point 12 and the kiln tail sealing point 13; the orifice of the second branch pipe 43 is communicated with the gate valve sealing point 14; the third branch pipes 37 are provided with three, and the pipe orifices of the three third branch pipes 37 are respectively communicated with the raw material feeding sealing point 15, the ash discharge sealing point 16 and the dust collector discharging sealing point 17; pressure sensors are arranged in the kiln head sealing point 12, the kiln tail sealing point 13, the gate valve sealing point 14, the raw material feeding sealing point 15, the ash discharge opening sealing point 16 and the dust collector discharging sealing point 17, and regulating fans are arranged in the first branch pipe, the second branch pipe 43 and the third branch pipe 37; the device also comprises a controller, wherein the controller is electrically connected with the regulating fan and the pressure sensor, and the controller can control and regulate the rotating speed of the fan through the actual pressure value fed back by the pressure sensor so as to control the density of CO2 gas in the kiln head sealing point 12, the kiln tail sealing point 13, the gate valve sealing point 14, the raw material feeding sealing point 15, the ash discharge sealing point 16 and the dust collector discharging sealing point 17, thereby forming a CO2 gas isolation layer and achieving the purpose of reducing air leakage.

The original sealing structure of the kiln head and the kiln tail of the rotary kiln 3 is that two ends (kiln head and kiln tail) of a rotary cylinder 24 are provided with a rotary cover body 23 and a fixed cover body 33, the rotary cover body 23 and the fixed cover body 33 are in sliding sealing through a packing sealing structure, the temperature of a sealing part is high when the rotary kiln 3 operates, and the cylinder of the sealing part rotates along with swinging and axial movement, so that air is easy to leak into the rotary kiln 3 from the packing sealing structure. As shown in fig. 3 to 5, the present embodiment provides a sealing structure at a kiln head sealing point 12 and a kiln tail sealing point 13, and a static friction ring cover 18 is additionally installed on the original kiln head and kiln tail sealing structure of the rotary kiln 3, and CO2 gas is introduced into the static friction ring cover 18 to form a CO2 insulating layer, so that air is prevented from entering the rotary kiln 3; specifically, the device comprises a rotary cover body 23, a static friction ring cover body 18 and a fixed cover body 33 which are sequentially arranged from inside to outside; the outer side of the rotary cover body 23 is connected with a static friction ring cover body 18 in a sliding sealing manner, a dynamic friction ring (a dynamic friction ring a22 and a dynamic friction ring b 32) is arranged on the rotary cover body 23, static friction rings (a static friction ring a21 and a static friction ring b 31) are arranged on two sides of the static friction ring cover body 18, the static friction ring a21 is tightly attached to the dynamic friction ring a22, and the static friction ring b31 is tightly attached to the dynamic friction ring b 32. When the rotary cylinder 24 moves along the axial direction, the static friction ring a21 and the dynamic friction ring a22, and the static friction ring b31 and the dynamic friction ring b32 are tightly attached; when the rotary cylinder 24 rotates and swings, the static friction ring a21 and the dynamic friction ring a22 keep fit and relatively slide between the static friction ring b31 and the dynamic friction ring b 32; the pressure sensor is arranged in the static friction ring cover 18, a first vent hole 1801 is formed in the static friction ring cover 18, and the output end of the first branch pipe is connected to the first vent hole 1801. The outside of the fixed cover body 33 is also provided with a packing seal structure, the packing seal structure comprises a packing seal a28 and a packing seal b29, the packing seal a28 is connected with the static friction ring cover body 18 which is arranged on the outer ring of the packing seal b29 and slides along with the static friction ring cover body 18 along the axial direction, and a spacing ring 26 is arranged between the packing seal a28 and the packing seal b 29.

The static friction ring cover 18 is also provided with an air vent c36 and an air vent b35, and the spacer ring 26 is provided with an air vent a34; the air hole c36 is positioned at the top of the static friction ring b31 at the right side of the static friction ring cover 18, and the air hole b35 is positioned between the filler seal a28 and the filler seal b29 at the bottom of the static friction ring cover 18. The carbon dioxide gas reaches the positions of the filler seal a28 and the filler seal b29 through the air holes c36, the air holes b35 and the air holes a34, and when a tiny gap appears between the filler seal b29 and the outer side of the sleeve of the fixed cover body 33, the carbon dioxide gas is filled into the rotary kiln 3; when a small gap appears between the packing seal a28 and the outer side of the sleeve of the fixed cover body 33, carbon dioxide gas overflows, and air cannot enter the rotary kiln 3.

The packing sealing structure is used for adjusting pressure through a pressure adjusting device 30, and the pressure adjusting device 30 is a bolt and nut compacting structure; the static friction ring cover 18 is fixedly connected with the fixed cover 33 through the bracket 19, and the static friction ring cover 18 is limited to rotate along the axis but can move along the axial direction.

The inner side of the fixed cover body 33 is provided with a hairbrush 27 and a scale steel sheet 25, the outer ends of the hairbrush 27 and the scale steel sheet 25 are fixed on the fixed cover body 33, and the inner ends are clung to the outer diameter of the rotary cylinder 24; because the hairbrush 27 and the fish scale steel sheet 25 have elasticity, the hairbrush can be tightly attached to the rotary cylinder 24 to play a dustproof role when the rotary cylinder 24 swings and axially moves, and the fly ash in the kiln is prevented from entering the areas of the dynamic friction ring b32, the static friction ring b31, the packing seal a28 and the packing seal b 29.

The outer side of the static friction ring cover body 18 is provided with a tensioning device 20, and one end of the tensioning device 20 is propped against the fixed cover body 33; the tensioning device 20 is a cylinder, a hydraulic rod, a spring tensioning or heavy hammer structure; tensioner 20 has a certain tension that provides force to static friction ring housing 18 tending to move away from fixed housing 33.

The bottom of the static friction ring cover 18 is provided with a dust discharging hole cover 1802, and the dust discharging hole cover 1802 is opened to facilitate cleaning dust in the static friction ring cover 18.

In the prior art, a packing 45 is generally adopted to pressurize a cover 44 to seal a valve plate 42, a lower valve body 40, a lifting rod 38 and an upper valve body 39, but the valve body of the gate valve is subjected to internal air flow and pressure difference at two sides of the valve plate 42, the valve plate 42 can shake, gaps are formed between the valve plate 42 and the lower valve body 40 and between the lifting rod 38 and the upper valve body 39 in sealing, and external air can enter a system from the gaps; the sealing part is improved, and the structure of the sealing point 14 of the gate valve after improvement is as follows: an outer cover 41 is provided on the upper valve body 39 of the gate valve, the upper end of the outer cover 41 is connected with the upper valve body 39, the lower end is connected with the lower valve body 40, a second vent hole is provided on the outer cover 41, and the output end of the second branch pipe 43 is connected to the second vent hole. When the valve plate 42 shakes, gaps appear between the valve plate 42 and the lower valve body 40 and between the lifting rod 38 and the upper valve body 39, and CO2 gas supplemented in the outer cover 41 leaks into the system through the gaps, so that air leakage is avoided, and the concentration of CO2 generated by the oxy-fuel combustion cement production line is improved.

In the traditional production line, because the raw material feeding point, the ash discharging opening of the waste heat utilization device 5 and the material discharging opening of the dust collector 6 are all fed by adopting a single rotary feeder, and because the pressure ratio of the outlet of the rotary feeder is smaller than that of the inlet, air can be filled into the system along the gap between the rotor blades of the rotary feeder and the shell; in this embodiment, the raw material feeding sealing point 15, the ash discharge opening sealing point 16 and the ash collector discharging sealing point 17 all adopt a double-rotation blanking device structure, which comprises a first blanking device 46 connected with a raw material blanking opening of the preheater 1, an ash discharge opening of the waste heat utilization device 5 or a blanking opening of the ash collector 6, a blanking pipe 48 is connected below the first blanking device 46, a second blanking device 47 is connected with the lower end of the blanking pipe 48, a third vent is formed in the blanking pipe 48, and the output end of the third branch pipe 37 is connected to the third vent. The controller is electrically connected with the motor of the first blanking device 46 and the motor of the second blanking device 47; the opening and closing of the first and

second downers

46 and 47 are controlled to control the blanking amount and prevent the blockage of materials.

When the raw material feeding device is used for feeding raw materials through a raw material feeding port of the preheater 1, the controller firstly controls the first feeder 46 to be opened, the raw materials fall into the feeding pipe 48, CO2 blown in through the third air vent extrudes air to prevent the air from entering the feeding pipe 48 through the first feeder 46, then the controller controls the first feeder 46 to be closed, the second feeder 47 is opened, the raw materials and the fed CO2 gas enter the preheater 1 through the second feeder 47, and the controller controls the second feeder 47 to be closed; the first and

second feeders

46, 47 are alternately opened as above until all green stock is discharged. When the ash discharge opening of the waste heat utilization device 5 discharges ash and the feed opening of the dust collector 6 discharges the material, the controller controls the first feeder 46 and the second feeder 47 to be alternately opened, and when the second feeder 47 is opened, CO2 is supplemented by the third air vent, so that air is prevented from being poured from the outlet of the second feeder 47.

s1: the cement production system operates in a total oxygen mode, and the outlet of the preheater 1 discharges CO2 smoke.

S2: the CO2 flue gas is subjected to waste heat utilization through a waste heat boiler, then enters a dust collector 6 through a high-temperature fan, and the CO2 flue gas subjected to dust removal through the dust collector 6 enters a condensing tower 7 for water removal; wherein the dust collector 6 is a bag type dust collector 6.

S3: part of the CO2 flue gas after water removal is sent to a CO2 circulating system 9, part of the CO2 flue gas is sent to the input end of a sealing gas pipe network 10, and the other part of the CO2 flue gas is sent to a CO2 storage point 11 for storage; wherein, one part of CO2 which is sent to the CO2 circulation system 9 is sent to the grate cooler 4 to be used as cooling air, and the other part is sent to the main burner to be used as mixed air.

Specifically comprises two processing steps:

(1) Referring to fig. 1, a part of CO2 flue gas dehydrated by a condensing tower 7 is delivered to a CO2 circulation system 9, the other part is delivered to a CO2 capturing system 8, a part of CO2 flue gas purified by the CO2 capturing system is delivered to an input end of a sealing gas pipe network 10, and the other part is delivered to a CO2 storage point 11 for storage.

(2) Referring to fig. 2, a part of CO2 flue gas dehydrated by the condensing tower 7 is delivered to the CO2 circulation system 9, a part of the flue gas is delivered to the input end of the sealing gas pipe network 10, a part of the flue gas is delivered to the CO2 capturing system 8, and the CO2 capturing system 8 is purified and then delivered to the CO2 storage point 11 for storage.

Wherein it is necessary to ensure that the concentration of CO2 gas delivered to the seal gas pipe network 10 is not less than 70%.

S4: CO2 flue gas is sent to a kiln head sealing point 12, a kiln tail sealing point 13, a gate valve sealing point 14, a raw material feeding sealing point 15, an ash discharge opening sealing point 16 and a dust collector discharging sealing point 17 through a sealing gas pipe network 10, and a CO2 isolation layer is formed at the kiln head sealing point 12, the kiln tail sealing point 13, the gate valve sealing point 14, the raw material feeding sealing point 15, the ash discharge opening sealing point 16 and the dust collector discharging sealing point 17.

S5: the pressure sensors monitor the pressures in the first branch pipe, the second branch pipe 43 and the third branch pipe 37, the gas pressure is fed back to the controller, the controller controls the rotation speeds of the regulating fans in the first branch pipe, the second branch pipe 43 and the third branch pipe 37 by comparing the actual values monitored by the comparison pressure sensors with preset pressure thresholds so as to regulate and control the pressures in the kiln head sealing point 12, the kiln tail sealing point 13, the flashboard valve sealing point 14, the raw material feeding sealing point 15, the ash discharge sealing point 16 and the dust collector discharging sealing point 17; the gas pressure thresholds in the first branch pipe, the second branch pipe 43 and the third branch pipe 37 are preset through the controller, when the actual pressure value monitored by the pressure sensor is smaller than the preset lower limit of the gas pressure threshold, the fan is controlled to increase the rotating speed and supplement more CO2 gas, and when the actual pressure value is larger than the preset upper limit of the gas pressure threshold, the fan is controlled to decrease the rotating speed or close, and the fed CO2 gas is reduced or stopped.

For example: the gas pressure threshold value set in the kiln head sealing point 12 is as follows: when the pressure sensor monitors that the pressure in the static friction ring cover 18 is greater than the ambient pressure +20pa, the control fan stops running, and when the pressure is less than the ambient pressure, the control fan is controlled to increase the pressure and the rotating speed, CO2 is introduced into the static friction ring cover 18, so that air leakage is isolated.

The foregoing description of the preferred embodiments of the invention is not intended to limit the scope of the claims, but rather to cover all equivalent modifications within the scope of the present invention as defined by the appended claims.

Claims

1. The carbon trapping auxiliary system for the cement production line comprises a kiln head sealing point and a kiln tail sealing point of a rotary kiln, wherein the kiln head and the kiln tail of the rotary kiln are respectively provided with a gate valve sealing point, a raw material discharging opening of a preheater is provided with a raw material feeding sealing point, an ash discharging opening of a waste heat utilization device is provided with an ash discharging opening sealing point, and a discharging opening of a dust collector is provided with a dust collector discharging sealing point; the method is characterized in that:

the device comprises a sealing gas pipe network, wherein CO2 gas dehydrated by a condensing tower is input to an input end of the sealing gas pipe network, a first branch pipe, a second branch pipe and a third branch pipe are arranged at an output end of the sealing gas pipe network, two first branch pipes are arranged, and pipe orifices of the two first branch pipes are respectively communicated to a kiln head sealing point and a kiln tail sealing point;

the pipe orifice of the second branch pipe is communicated with the gate valve sealing point;

the third branch pipes are provided with three pipe orifices which are respectively communicated with a raw material feeding sealing point, an ash discharging opening sealing point and a dust collector discharging sealing point;

pressure sensors are arranged in the kiln head sealing point, the kiln tail sealing point, the gate valve sealing point, the raw material feeding sealing point, the ash discharge opening sealing point and the dust collector discharging sealing point, and regulating fans are arranged in the first branch pipe, the second branch pipe and the third branch pipe;

the controller is electrically connected with the regulating fan and the pressure sensor;

the sealing structures at the kiln head sealing point and the kiln tail sealing point are that a rotary cover body and a fixed cover body are arranged at the kiln head and the kiln tail of the rotary kiln,

comprises a rotary cover body, a static friction ring cover body and a fixed cover body which are sequentially arranged from inside to outside; the rotary cover body is externally and hermetically connected with a static friction ring cover body, a dynamic friction ring (a 22) and a dynamic friction ring (b 32) are arranged on the rotary cover body, static friction rings (a 21) and static friction rings (b 31) are arranged on two sides of the static friction ring cover body, the static friction rings (a 21) are tightly attached to the dynamic friction rings (a 22), and the static friction rings (b 31) are tightly attached to the dynamic friction rings (b 32);

the pressure sensor is arranged in the static friction ring cover body, a first vent hole is formed in the static friction ring cover body, and the output end of the first branch pipe is connected to the first vent hole; the outer side of the fixed cover body is also provided with a filler sealing structure, the filler sealing structure comprises a filler seal (a 28) and a filler seal (b 29), the filler seal (a 28) is connected with a static friction ring cover body of the outer ring of the filler seal (b 29) and slides along with the static friction ring cover body along the axial direction, and a spacer ring is arranged between the filler seal (a 28) and the filler seal (b 29);

the static friction ring cover body is also provided with an air vent (c 36) and an air vent (b 35), and the spacing ring is provided with an air vent (a 34); the air holes (c 36) are positioned at the top of the static friction ring (b 31) on the right side of the static friction ring cover body, and the air holes (b 35) are positioned between the bottom packing seal (a 28) and the packing seal (b 29) of the static friction ring cover body;

the packing sealing structure adjusts pressure through a pressure adjusting device, and the pressure adjusting device is a bolt and nut compacting structure; the static friction ring cover body is fixedly connected with the fixed cover body through a bracket, and the static friction ring cover body is limited to rotate along the axis but can move along the axial direction;

the outer side of the static friction ring cover body is provided with a tensioning device, and one end of the tensioning device is propped against the fixed cover body; the tensioning device is of a cylinder, a hydraulic rod and a spring tensioning or heavy hammer structure; the tensioner has a certain tension that provides a force to the static friction ring housing that tends to move away from the stationary housing.

2. The carbon capture auxiliary system for a cement production line according to claim 1, wherein: the gate valve sealing point is structured that a lifting rod of the gate valve is sealed with an upper valve body, a valve plate is sealed with a lower valve body by a gland, an outer cover body is arranged on the upper valve body of the gate valve, a second ventilation hole is arranged on the outer cover body, and the output end of the second branch pipe is connected to the second ventilation hole.

3. The carbon capture auxiliary system for a cement production line according to claim 1, wherein: the raw material feeding sealing point, the ash discharging opening sealing point and the dust collector discharging sealing point all adopt a double-rotation blanking device structure, and the double-rotation blanking device comprises a first blanking device connected with a raw material discharging opening of a preheater, an ash discharging opening of a waste heat utilization device or a blanking opening of the dust collector, a blanking pipe is connected below the first blanking device, a second blanking device is connected with the lower end of the blanking pipe, a third air vent is formed in the blanking pipe, and the output end of a third branch pipe is connected to the third air vent.

4. A carbon capture assist system for a cement production line according to claim 3, characterized in that: the controller is electrically connected with the motor of the first blanking device and the motor of the second blanking device.

5. A CO2 sealing method for a cement production line, characterized by using the carbon capture auxiliary system for a cement production line according to claim 1, comprising the following specific steps:

6. The CO2 sealing method for a cement production line according to claim 5, wherein: in step S3, a part of CO2 flue gas after water removal is conveyed to a CO2 capturing system, CO2 flue gas purified by the CO2 capturing system is conveyed to an input end of a sealing gas pipe network, and the other part of CO2 flue gas is conveyed to a CO2 storage point for storage.

7. The CO2 sealing method for a cement production line according to claim 5, wherein: the concentration of CO2 gas conveyed into the sealing gas pipe network is not less than 70 percent.