Cement kiln tail gas treatment system and method

Abstract

An embodiment of the present invention provides a flue gas treatment system and method at the tail end of a cement kiln. The system includes a waste heat boiler, a high-temperature fan, a denitrification tower, a raw material mill, a circulating fan, a kiln tail dust collector, and a tail exhaust fan. The system also includes multiple valves for controlling the opening and closing of pipelines and multiple water spraying points for reducing the temperature of flue gas in the pipeline; the inlet of the high-temperature fan is connected to the preheater outlet of the cement kiln; the flue gas treatment system and method can be applied to flue gas treatment under different production conditions at the tail end of the cement kiln, reasonably set the connection relationship between different equipment, and set water spraying points and valves near each equipment. By adjusting the opening and closing of the valves and the opening and closing of the water spraying points, the water spraying amount can be adapted to the cooling requirements of different equipment, ensuring that the flue gas temperature entering different equipment under different production conditions meets the requirements. The entire flue gas treatment system at the tail end of the cement kiln has the advantages of reducing flue gas temperature, improving dust removal efficiency, and reducing energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas treatment, and more particularly to a cement kiln tail flue gas treatment system and method. Background Art

[0002] With the continuous advancement and adjustment of SCR (Selective Catalytic Reduction) denitrification technology in the cement industry, the medium-temperature and medium-dust SCR technology route has been widely promoted and applied. Medium-temperature and medium-dust SCR technology refers to a denitrification process developed based on the characteristics of cement kilns and the medium-temperature and medium-dust conditions on site.

[0003] Because the space at the tail end of a cement plant kiln is very limited, most current medium-temperature, medium-dust SCR denitrification systems choose to remove the original kiln tail humidification tower and utilize the original humidification tower foundation. Although this solves the denitrification tower's land occupation problem, without a humidification tower to cool the flue gas, it cannot meet the cooling requirements of various production conditions, resulting in overheating during cement kiln production operations. Overheating problems are mainly manifested in high flue gas temperatures entering the kiln tail dust collector, increased operating flue gas volume, and increased filtration velocity at the kiln tail dust collector. The increased filtration velocity at the kiln tail dust collector increases system resistance, reducing the dust removal efficiency of the kiln tail dust collector. In addition, when the flue gas temperature entering the kiln tail dust collector exceeds the temperature resistance of the filter bags, the filter bags will burn out or their service life will be shortened.

[0004] Related technologies include using simple pipeline cooling to cool the flue gas at the kiln tail, but the location design of the cooling pipeline and flue gas dust removal equipment, denitrification tower and other equipment is unreasonable. The use of unified cooling measures for various production conditions leads to excessive overall water spraying, resulting in increased energy consumption and wet bottom ash blockage problems.

[0005] Therefore, after dismantling the kiln tail humidification tower, how to reasonably arrange the cooling equipment, flue gas dust removal equipment, denitrification tower and other equipment in the kiln tail flue gas treatment system to achieve the purpose of lowering the flue gas temperature, improving the dust removal efficiency and reducing energy consumption is an urgent problem to be solved in the medium-temperature and medium-dust SCR denitrification technology. Summary of the Invention

[0006] The embodiment of the present invention provides a cement kiln tail flue gas treatment system and method, which are used to solve the problems of excessive overall water spraying, increased energy consumption and wet bottom ash blockage in the cement kiln tail flue gas treatment system in the related art.

[0007] An embodiment of the present invention provides a cement kiln tail flue gas treatment system, comprising a waste heat boiler, a high-temperature fan, a denitrification tower, a raw material mill, a circulating fan, a kiln tail dust collector, and a tail exhaust fan. The system also includes multiple valves for controlling the opening and closing of pipelines and multiple water spray points for reducing the flue gas temperature in the pipelines. The inlet of the high-temperature fan is connected to the outlet of the cement kiln preheater.

[0008] The first of the multiple water spraying points is arranged on the first pipe between the outlet of the preheater and the inlet of the high-temperature fan; the second water spraying point is arranged on the second pipe between the outlet of the high-temperature fan and the inlet of the denitrification tower; the third and fourth water spraying points are arranged in sequence on the third pipe between the outlet of the denitrification tower and the inlet of the kiln tail dust collector;

[0009] The waste heat boiler is arranged in parallel between the outlet of the first water spraying point and the inlet of the high-temperature fan; the raw material mill and the circulating fan are arranged in parallel between the outlet of the denitrification tower and the outlet of the fourth water spraying point; the outlet of the kiln tail dust collector is connected to the inlet of the tail exhaust fan, and the outlet of the tail exhaust fan is connected to the chimney; the first valve of the multiple valves is arranged on the second pipe; the second valve and the third valve are arranged on the fourth pipe in sequence, and the fourth pipe is a pipe located between the outlet of the second water spraying point and the inlet of the raw material mill; the fourth valve is arranged on the fifth pipe, and the fifth pipe is a pipe located between the outlet of the second valve and the inlet of the fourth water spraying point; the fifth valve is arranged between the outlet of the third water spraying point and the inlet of the fourth water spraying point on the third pipe; the sixth valve is arranged on the sixth pipe, and the sixth pipe is a pipe located between the outlet of the third valve and the inlet of the third water spraying point.

[0010] Optionally, each of the water spraying points is provided with at least one spray gun and an inlet and outlet temperature transmitter.

[0011] Optionally, the pipes are all non-standard pipes.

[0012] Optionally, when the waste heat boiler is running, the denitrification tower is bypassed, and the raw material mill is running, and the second valve and the third valve are open, and the first valve, the fourth valve, and the fifth valve are closed, the flue gas in the system flows to the waste heat boiler, the high-temperature fan, the raw material mill, and the kiln tail dust collector in this order;

[0013] When the waste heat boiler is running, the denitrification tower is running, and the raw material mill is running, and the second valve, the third valve, the fourth valve and the fifth valve are closed, and the first valve and the sixth valve are opened, the flue gas in the system flows in the order of the waste heat boiler, the high-temperature fan, the denitrification tower, the raw material mill and the kiln tail dust collector.

[0014] Optionally, when the waste heat boiler is running, the denitrification tower and the raw material mill are bypassed, and the second valve and the fourth valve are opened, and the first valve, the third valve, the fifth valve, and the sixth valve are closed, the flue gas in the system flows to the waste heat boiler, the high-temperature fan, and the kiln tail dust collector in this order;

[0015] When the waste heat boiler is running, the denitrification tower is running, the raw material mill is bypassed, and the first valve and the fifth valve are opened, and the second valve, the third valve, the fourth valve and the sixth valve are closed, the flue gas in the system flows in sequence to the waste heat boiler, the high-temperature fan, the denitrification tower and the kiln tail dust collector.

[0016] Optionally, when the waste heat boiler bypass, the denitrification tower bypass, and the raw material mill are in operation, and the second valve and the third valve are open, and the first valve, the fourth valve 16, the fifth valve, and the sixth valve are closed, the flue gas in the system flows to the high-temperature fan, the raw material mill, and the kiln tail dust collector in sequence;

[0017] When the waste heat boiler is bypassed, the denitrification tower and the raw material mill are in operation, and the first valve and the sixth valve are opened, and the second valve, the third valve, the fourth valve and the fifth valve are closed, the flue gas in the system flows to the high-temperature fan, the denitrification tower, the raw material mill and the kiln tail dust collector in sequence.

[0018] Optionally, when the waste heat boiler, the denitrification tower and the raw material mill are all bypassed, and the second valve and the fourth valve are opened, and the first valve, the third valve, the fifth valve and the sixth valve are closed, the flue gas in the system flows to the high-temperature fan and the kiln tail dust collector in sequence;

[0019] When the waste heat boiler is bypassed, the denitrification tower is running, the raw material mill is bypassed, and the first valve and the fifth valve are opened, and the second valve, the third valve, the fourth valve and the sixth valve are closed, the flue gas in the system flows to the high-temperature fan, the denitrification tower and the kiln tail dust collector in sequence.

[0020] The embodiment of the present invention further provides a method for treating cement kiln tail gas, comprising:

[0021] When the flue gas in the system flows to the waste heat boiler, the high-temperature fan, the raw material mill and the kiln tail dust collector in sequence, and the inlet temperature of the waste heat boiler does not exceed the preset temperature threshold, each water spray point in the system is closed;

[0022] When the flue gas in the system flows in the order of the waste heat boiler, the high-temperature fan, the denitrification tower, the raw material mill and the kiln tail dust collector, and the inlet temperature of the waste heat boiler does not exceed the preset temperature threshold, each water spray point in the system is closed;

[0023] When the flue gas in the system flows sequentially to the waste heat boiler, the high-temperature fan, and the kiln tail dust collector, firstly open the second water spray point to reduce the flue gas temperature in the pipeline from the first temperature to the second temperature, and then open the fourth water spray point to reduce the flue gas temperature from the second temperature to the third temperature;

[0024] When the flue gas in the system flows sequentially through the waste heat boiler, the high-temperature fan, the denitrification tower, and the kiln tail dust collector, firstly open the third water spray point to reduce the flue gas temperature in the pipeline from the first temperature to the second temperature, and then open the fourth water spray point to reduce the flue gas temperature from the second temperature to the third temperature;

[0025] When the flue gas in the system flows sequentially toward the high-temperature fan, the raw material mill, and the kiln tail dust collector, opening the first water spray point to reduce the flue gas temperature from the fourth temperature to the first temperature;

[0026] When the flue gas in the system flows sequentially to the high-temperature fan, the denitrification tower, the raw material mill, and the kiln tail dust collector, the first water spray point is opened to reduce the flue gas temperature from the fourth temperature to the first temperature;

[0027] When the flue gas in the system flows sequentially toward the high-temperature fan and the kiln tail dust collector, firstly, the first water spray point is opened to reduce the flue gas temperature from the fourth temperature to the first temperature, then the second water spray point is opened to reduce the flue gas temperature from the first temperature to the second temperature, and finally, the fourth water spray point is opened to reduce the flue gas temperature from the second temperature to the third temperature;

[0028] When the flue gas in the system flows in sequence to the high-temperature fan, the denitrification tower and the kiln tail dust collector, first open the first water spray point to reduce the flue gas temperature from the fourth temperature to the first temperature, then open the third water spray point to reduce the flue gas temperature from the first temperature to the second temperature, and finally open the fourth water spray point to reduce the flue gas temperature from the second temperature to the third temperature.

[0029] Optionally, when the flue gas in the system flows to the waste heat boiler, the high-temperature fan, the raw material mill and the kiln tail dust collector in sequence, and the inlet temperature of the waste heat boiler exceeds the temperature threshold, the first water spray point in the system is opened for cooling.

[0030] Optionally, the first temperature is 220°C, the second temperature is 200°C, the third temperature is 180°C, and the fourth temperature is 320°C.

[0031] The embodiments of the present invention have at least the following beneficial effects:

[0032] The embodiment of the present invention provides a flue gas treatment system at the tail end of a cement kiln, which includes a waste heat boiler, a high-temperature fan, a denitrification tower, a raw material mill, a circulating fan, a dust collector at the tail end of the kiln, and a tail exhaust fan. It also includes multiple valves for controlling the opening and closing of the pipeline and multiple water spraying points for reducing the temperature of the flue gas in the pipeline; the inlet of the high-temperature fan is connected to the outlet of the preheater of the cement kiln; the flue gas treatment system can be applied to the flue gas treatment under different production conditions at the tail end of the cement kiln, and the connection relationship between different equipment is reasonably set, and water spraying points and valves are set near each equipment. By adjusting the opening and closing of the valves and the opening and closing of the water spraying points, the water spraying amount is adapted to the cooling requirements of different equipment, ensuring that the flue gas temperature entering different equipment under different production conditions meets the requirements. The entire flue gas treatment system at the tail end of the cement kiln has the advantages of reducing the flue gas temperature, improving the dust removal efficiency, and reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 A connection diagram of a cement kiln tail gas treatment system provided by an embodiment of the present invention;

[0035] Figure 2 The present invention provides a flow chart of a method for treating flue gas from a cement kiln.

[0036] Reference numerals:

[0037] 1-Preheater; 2-First water spraying point; 3-Waste heat boiler; 4-High temperature fan; 5-Second water spraying point; 6-First valve; 7-Denitrification tower; 8-Third water spraying point; 9-Fifth valve; 10-Fourth water spraying point; 11-Second valve; 12-Third valve; 13-Sixth valve; 14-Raw material mill; 15-Circulating fan; 16-Fourth valve; 17-Kiln tail dust collector; 18-Tail exhaust fan; 19-Chimney; 20-First pipeline; 21-Second pipeline; 22-Third pipeline; 23-Fourth pipeline; 24-Fifth pipeline; 25-Sixth pipeline. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] Figure 1 This is a schematic diagram of a cement kiln tail gas treatment system connection provided by an embodiment of the present invention. Figure 1 As shown, it includes a waste heat boiler 3, a high-temperature fan 4, a denitrification tower 7, a raw material mill 14, a circulating fan 15, a kiln tail dust collector 17, and a tail exhaust fan 18. The system also includes multiple valves for controlling the opening and closing of the pipeline and multiple water spraying points for reducing the flue gas temperature in the pipeline.

[0040] Specifically, the waste heat boiler 3 is used to reduce the temperature of the flue gas and use the waste heat to generate electricity or apply it to other production needs; the inlet of the high-temperature fan 4 is connected to the outlet of the preheater 1 of the cement kiln. The high-temperature fan 4 is the power source of the system. The preheater 1 is under negative pressure, and the flue gas flow is powered by the high-temperature fan 4, which transports the flue gas to the flue gas treatment system. The denitrification tower 7 is used to treat sulfur dioxide and nitrogen oxides in the flue gas, reduce their emissions, and alleviate environmental pollution. The raw material mill 14 uses the flue gas in the system as a heat source to dry the raw materials. Due to heat exchange, the temperature of the flue gas passing through the raw material mill 14 is reduced. At the same time, the circulating fan 15 is also used to ventilate the system and transport the flue gas in the system.

[0041] Among them, the first water spraying point 2 of the multiple water spraying points is set on the first pipe 20 between the outlet of the preheater 1 and the inlet of the high-temperature fan 4; the second water spraying point 5 is set on the second pipe 21 between the outlet of the high-temperature fan 4 and the inlet of the denitrification tower 7; the third water spraying point 8 and the fourth water spraying point 10 are sequentially set on the third pipe 22 between the outlet of the denitrification tower 7 and the inlet of the kiln tail dust collector 17;

[0042] Specifically, the first water spray point 2 is arranged on the first pipe 20 between the outlet of the preheater 1 and the inlet of the high-temperature blower 4, and is used to cool the flue gas coming out of the preheater 1 and control the flue gas temperature entering the high-temperature blower 4.

[0043] The second water spraying point 5 is set on the second pipe 21 between the outlet of the high-temperature blower 4 and the inlet of the denitrification tower 7, and is used to cool the flue gas passing through the high-temperature blower 4 and control the temperature of the flue gas entering the denitrification tower 7.

[0044] The third and fourth water spray points 8, 10 are sequentially arranged on the third pipe 22 between the outlet of the denitrification tower 7 and the inlet of the kiln tail dust collector 17. The third water spray point 8 is mainly used to cool the flue gas passing through the denitrification tower 7 and control the flue gas temperature entering the kiln tail dust collector 17. The fourth water spray point 10 is mainly used to cool the flue gas after passing through the high-temperature fan 4 and cooling at the water spray point 2, and control the flue gas temperature entering the kiln tail dust collector 17. Finally, the kiln tail dust collector 17 discharges the dust-removed flue gas into the atmosphere through the exhaust fan 18 through the smoke 19.

[0045] The waste heat boiler 3 is arranged in parallel between the outlet of the first water spraying point 2 and the inlet of the high-temperature fan 4; the raw material mill 14 and the circulating fan 15 are arranged in parallel between the outlet of the denitrification tower 7 and the outlet of the fourth water spraying point 10; the outlet of the kiln tail dust collector 17 is connected to the inlet of the tail exhaust fan 18, and the outlet of the tail exhaust fan is connected to the chimney 19; the first valve 6 among the multiple valves is arranged on the second pipe 21; the second valve 11 and the third valve 12 are arranged in sequence on the fourth pipe 23, and the fourth pipe 23 is a pipe located between the outlet of the second water spraying point 5 and the inlet of the raw material mill 14; the fourth valve 16 is arranged on the fifth pipe 24, and the fifth pipe 24 is a pipe located between the outlet of the second valve 11 and the inlet of the fourth water spraying point 10; the fifth valve 9 is arranged between the outlet of the third water spraying point 8 and the inlet of the fourth water spraying point 10 on the third pipe 22; the sixth valve 13 is arranged on the sixth pipe 25, and the sixth pipe 25 is a pipe located between the outlet of the third valve 12 and the inlet of the third water spraying point 8.

[0046] Specifically, the waste heat boiler 3 is arranged in parallel between the outlet of the first water spraying point 2 and the inlet of the high-temperature fan 4. When the waste heat boiler 3 operates normally, the flue gas coming out of the preheater 1 passes through the first water spraying point 2 and then enters the high-temperature fan 4 through the waste heat boiler 3. When the waste heat boiler 3 is bypassed, the flue gas coming out of the preheater 1 passes through the first water spraying point 2 and directly enters the high-temperature fan 4.

[0047] The raw material mill 14 and the circulating fan 15 are arranged in parallel between the outlet of the denitrification tower 7 and the outlet of the fourth water spray point 10. When the denitrification tower 7 is in operation and the raw material mill 14 is bypassed, the flue gas passing through the denitrification tower 7 passes through the third water spray point 8 and the fourth water spray point 10 in sequence, and finally enters the kiln tail dust collector 17. When the denitrification tower 7 is in operation and the raw material mill 14 is in operation, the flue gas from the denitrification tower 7 enters the raw material mill 14 and, under the action of the circulating fan 15, enters the kiln tail dust collector 17.

[0048] The outlet of the kiln tail dust collector 17 is connected to the inlet of the tail exhaust fan 18, and the outlet of the tail exhaust fan 18 is connected to the chimney 19. The flue gas after dust removal by the kiln tail dust collector 17 is discharged into the chimney 19 under the action of the tail exhaust fan 18, and then discharged into the atmosphere.

[0049] The first valve 6 is arranged on the second pipeline 21, and the second pipeline 21 is controlled by the first valve 6, that is, when the first valve 6 is opened, the high-temperature fan 4 and the denitrification tower 7 are connected, and correspondingly, when the first valve 6 is closed, the high-temperature fan 4 and the denitrification tower 7 are disconnected, that is, it is used to control whether the flue gas passing through the second water spraying point 5 can enter the denitrification tower 7; the second valve 11 and the third valve 12 are arranged on the fourth pipeline 23 in sequence, and the fourth pipeline 23 is a pipeline located between the outlet of the second water spraying point 5 and the inlet of the raw material mill 14. The second valve 11 is mainly used to control whether the flue gas can pass through the third valve 12 and the fourth valve 16, the third valve 12 is used to control whether the flue gas can enter the raw material mill 14; the fourth valve 16 is arranged on the fifth pipe 24, and is used to control whether the flue gas in the fifth pipe 24 can enter the kiln tail dust collector 17. The fifth pipe 24 is a pipe located between the outlet of the second valve 11 and the inlet of the fourth water spraying point 10; the fifth valve 9 is arranged between the outlet of the third water spraying point 8 and the inlet of the fourth water spraying point 10 on the third pipe 22; the sixth valve 13 is arranged on the sixth pipe 25, and the sixth pipe 25 is a pipe located between the outlet of the third valve 12 and the inlet of the third water spraying point 8.

[0050] In summary, the flue gas treatment system at the tail end of a cement kiln provided by an embodiment of the present invention includes a waste heat boiler, a high-temperature fan, a denitrification tower, a raw material mill, a circulating fan, a dust collector at the tail end of a kiln, and a tail exhaust fan. The system also includes multiple valves for controlling the opening and closing of pipelines and multiple water spraying points for reducing the temperature of flue gas in the pipeline; the inlet of the high-temperature fan is connected to the preheater outlet of the cement kiln; the flue gas treatment system and method can be applied to flue gas treatment under different production conditions at the tail end of a cement kiln, and the connection relationship between different equipment is reasonably set, and water spraying points and valves are set near each equipment. By adjusting the opening and closing of the valves and the opening and closing of the water spraying points, the water spraying amount can be adapted to the cooling requirements of different equipment, ensuring that the flue gas temperature entering different equipment under different production conditions meets the requirements. The entire flue gas treatment system at the tail end of a cement kiln has the advantages of reducing flue gas temperature, improving dust removal efficiency, and reducing energy consumption.

[0051] In a possible implementation manner, each of the water spraying points is provided with at least one spray gun and an inlet and outlet temperature transmitter.

[0052] Specifically, each water spray point is equipped with at least one spray gun and inlet and outlet temperature transmitters. A specific number of spray guns is designed for each water spray point based on the actual pipe length, angle, and other factors to achieve different temperature reduction requirements. If the actual pipe is long and the temperature difference to be reduced is small, a small number of spray guns can be designed to meet the temperature reduction requirements. If the water spray pipe is short and the temperature difference to be reduced is large, more spray guns are required to meet the temperature reduction requirements. In addition, a temperature transmitter is installed at each water spray point to detect the current temperature of the water spray point, convert the temperature signal into an electrical signal, and transmit it to the central control center. The control center then controls the opening and closing of the water spray device, as well as the flow rate and pressure of the spray guns, to achieve the required temperature reduction.

[0053] In a possible implementation manner, all pipelines are non-standard pipelines.

[0054] Specifically, all pipelines are non-standard pipelines. The original non-standard pipelines are used as cooling pipelines, which does not require new equipment, reduces costs, and does not occupy site space.

[0055] In one possible embodiment, when the waste heat boiler 3 is running, the denitrification tower 7 is bypassed, the raw material mill 14 is running, and the second valve 11 and the third valve 12 are open, and the first valve 6, the fourth valve 16 and the fifth valve 9 are closed, the flue gas in the system flows in the order of the waste heat boiler 3, the high-temperature fan 4, the raw material mill 14 and the kiln tail dust collector 17.

[0056] When the waste heat boiler 3, the denitrification tower 7 and the raw material mill 14 are running, and the second valve 11, the third valve 12, the fourth valve 16 and the fifth valve 9 are closed, and the first valve 6 and the sixth valve 13 are opened, the flue gas in the system flows in the order of the waste heat boiler 3, the high-temperature fan 4, the denitrification tower 7, the raw material mill 14 and the kiln tail dust collector 17.

[0057] In one possible embodiment, when the waste heat boiler 3 is running, the denitrification tower 7 is bypassed, the raw material mill 14 is bypassed, and the second valve 11 and the fourth valve 16 are opened, and the first valve 6, the third valve 12, the fifth valve 9, and the sixth valve 13 are closed, the flue gas in the system flows to the waste heat boiler 3, the high-temperature fan 4, and the kiln tail dust collector 17 in sequence.

[0058] When the waste heat boiler 3 is running, the denitrification tower 7 is running, the raw material mill 14 is bypassed, the first valve 6 and the fifth valve 9 are open, and the second valve 11, the third valve 12, the fourth valve 16 and the sixth valve 13 are closed, the flue gas in the system flows to the waste heat boiler 3, the high-temperature fan 4, the denitrification tower 7 and the kiln tail dust collector 17 in sequence.

[0059] In one possible embodiment, when the waste heat boiler 3 is bypassed, the denitrification tower 7 is bypassed, the raw material mill 14 is running, and the second valve 11 and the third valve 12 are opened, and the first valve 6, the fourth valve 16, the fifth valve and the sixth valve 13 are closed, the flue gas in the system flows to the high-temperature fan 4, the raw material mill 14 and the kiln tail dust collector 17 in sequence.

[0060] When the waste heat boiler 3 is bypassed, the denitrification tower 7 is in operation, the raw material mill 14 is in operation, and the first valve 6 and the sixth valve 13 are opened, and the second valve 11, the third valve 12, the fourth valve 16 and the fifth valve 9 are closed, the flue gas in the system flows to the high-temperature fan 4, the denitrification tower 7, the raw material mill 14 and the kiln tail dust collector 17 in sequence.

[0061] In one possible embodiment, when the waste heat boiler 3, the denitrification tower 7 and the raw material mill 14 are all bypassed, and the second valve 11 and the fourth valve 16 are opened, and the first valve 6, the third valve 12, the fifth valve 9 and the sixth valve 13 are closed, the flue gas in the system flows to the high-temperature fan 4 and the kiln tail dust collector 17 in sequence.

[0062] When the waste heat boiler 3 is bypassed, the denitrification tower 7 is running, the raw material mill 14 is bypassed, and the first valve 6 and the fifth valve 9 are opened, and the second valve 11, the third valve 12, the fourth valve 16 and the sixth valve 13 are closed, the flue gas in the system flows to the high-temperature fan 4, the denitrification tower 7 and the kiln tail dust collector 17 in sequence.

[0063] Specifically, equipment bypass means that during the cement kiln tail production process, when the equipment is shut down or under maintenance, the flue gas does not pass through a certain device but passes through other pipelines. Equipment operation means that the equipment is working normally and the flue gas passes through the current equipment.

[0064] When waste heat boiler 3 is bypassed, the flue gas from preheater 1 is blocked from entering waste heat boiler 3, causing the flue gas to enter high-temperature fan 4 through first conduit 20. When raw material mill 14 is bypassed, the flue gas from high-temperature fan 4 is blocked from entering raw material mill 14, causing the flue gas to enter second conduit 21 and fifth conduit 24 from high-temperature fan 4. When denitrification tower 7 is bypassed, the flue gas from high-temperature fan 4 is blocked from entering denitrification tower 7, causing the flue gas to enter second conduit 21 from high-temperature fan 4 and then enter fourth conduit 23 and fifth conduit 24, respectively.

[0065] The first valve 6 is used to control the flow between the second pipeline 21 and the denitrification tower 7. When the first valve 6 is closed, the flue gas enters the fourth pipeline 23 and the fifth pipeline 24 through the second pipeline 21. The second valve 11 is used to control the flow between the second pipeline 21 and the fourth pipeline 23 and the fifth pipeline 24. When the second valve 11 is closed, the flue gas from the high-temperature fan 4 enters the denitrification tower 7 through the second pipeline 21. The third valve 12 is used to control the flow between the second pipeline 21 and the fourth pipeline 23. When the third valve 12 is closed, the flue gas from the high-temperature fan 4 enters the fifth pipeline 24 through the second pipeline 21. The fourth valve 16 is used to control the flow between the fifth pipeline 24. When the fourth valve 16 is closed, the flue gas from the high-temperature fan 4 enters the fourth pipeline 23 through the second pipeline 21. The fifth valve 9 is used to control the conduction of the third pipeline 22. When the fifth valve 9 is closed, the flue gas coming out of the denitrification tower 7 enters the sixth pipeline 25; the sixth valve 13 is used to control the conduction of the sixth pipeline 25. When the sixth valve 13 is closed, the flue gas coming out of the denitrification tower 7 enters the third pipeline 22.

[0066] In order to more clearly introduce the cement kiln tail gas treatment system provided by the embodiment of the present invention, the following Figure 2 , which introduces the processing method of this system in detail.

[0067] like Figure 2 As shown, the treatment method of the cement kiln tail flue gas treatment system includes the following steps:

[0068] In step 101, when the flue gas in the system flows to the waste heat boiler 3, the high temperature fan 4, the raw material mill 14 and the kiln tail dust collector 17 in sequence, and the inlet temperature of the waste heat boiler 3 does not exceed the preset temperature threshold, each water spraying point in the system is closed.

[0069] Specifically, the flue gas temperature coming out of the preheater 1 is the fourth temperature. When the inlet temperature of the waste heat boiler 3 does not exceed the preset temperature threshold, the flue gas in the system passes through the waste heat boiler 3 and the flue gas temperature is the first temperature. After the flue gas continues to absorb heat through the raw material mill 14, the flue gas temperature drops to about the third temperature and enters the kiln tail dust collector 17. At this temperature, the dust removal efficiency of the kiln tail dust collector 17 can be guaranteed. Therefore, there is no need to spray water points to cool the flue gas in the system, and all water spray points in the system are closed. If the flue gas temperature entering the tail dust collector is high and the working flue gas volume increases, the filtering wind speed of the kiln tail dust collector 17 will increase, which will increase the system resistance and reduce the dust removal efficiency.

[0070] Step 102: When the flue gas in the system flows to the waste heat boiler 3, the high-temperature fan 4, the denitrification tower 7, the raw material mill 14 and the kiln tail dust collector 17 in sequence, and the inlet temperature of the waste heat boiler 3 does not exceed the preset temperature threshold, each water spray point in the system is closed.

[0071] Similar to step 101, the flue gas temperature coming out of the preheater 1 is the fourth temperature. When the inlet temperature of the waste heat boiler 3 does not exceed the fourth temperature, part of the heat of the flue gas will be absorbed after the flue gas passes through the waste heat boiler 3 and the raw material mill 14. The flue gas that has absorbed part of the heat will reach a temperature below the third temperature after passing through the raw material mill 14, and then enter the kiln tail dust collector 17. Under this working condition, all water spray points in the system are closed.

[0072] Step 103, when the flue gas in the system flows to the waste heat boiler 3, the high-temperature fan 4 and the kiln tail dust collector 17 in sequence, first open the second water spray point 5 to reduce the flue gas temperature in the pipeline from the first temperature to the second temperature, and then open the fourth water spray point 10 to reduce the flue gas temperature from the second temperature to the third temperature.

[0073] Specifically, the flue gas temperature coming out of the preheater 1 is the fourth temperature. After the flue gas passes through the waste heat boiler 3, the temperature is the first temperature. At this time, the second water spray point 5 is opened first to reduce the flue gas temperature in the pipeline from the first temperature to the second temperature, and then the fourth water spray point 10 is opened to reduce the flue gas temperature from the second temperature to below the third temperature, ensuring that the temperature entering the kiln tail dust collector 17 is not higher than the third temperature. If the temperature entering the kiln tail dust collector 17 is higher than the third temperature, the working flue gas volume will increase, the filtration wind speed of the kiln tail dust collector 17 will increase, and the system resistance will increase, thereby reducing the dust removal efficiency.

[0074] Step 104, when the flue gas in the system flows to the waste heat boiler 3, the high-temperature fan 4, the denitrification tower 7 and the kiln tail dust collector 17 in sequence, first open the third water spray point 8 to reduce the flue gas temperature in the pipeline from the first temperature to the second temperature, and then open the fourth water spray point 10 to reduce the flue gas temperature from the second temperature to the third temperature. Similarly, it is ensured that the flue gas temperature entering the kiln tail dust collector 17 does not exceed the third temperature.

[0075] Specifically, the flue gas exiting the preheater 1 has a temperature of the fourth temperature. After passing through the waste heat boiler 3, the flue gas has a temperature of the first temperature. Under the action of the high-temperature fan 4, the flue gas at the first temperature is transported to the denitrification tower 7. The flue gas exiting the denitrification tower 7 enters the kiln tail dust collector 17 through the third water spray point 8 and the fourth water spray point 10. Activating the third water spray point 8 lowers the temperature of the flue gas exiting the denitrification tower 7 from the first temperature to the second temperature. Activating the fourth water spray point 10 then lowers the temperature of the flue gas from the second temperature to the third temperature, ensuring that the flue gas temperature entering the kiln tail dust collector 17 does not exceed the third temperature.

[0076] Step 105 , when the flue gas in the system flows to the high-temperature fan 4 , the raw material mill 14 and the kiln tail dust collector 17 in sequence, the first water spraying point 2 is opened to reduce the flue gas temperature from the fourth temperature to the first temperature.

[0077] Specifically, the flue gas temperature coming out of the preheater 1 is the fourth temperature. Before the flue gas enters the high-temperature fan 4, the first water spray point 2 is opened to reduce the flue gas temperature from the fourth temperature to the first temperature, ensuring that the flue gas temperature entering the high-temperature fan 4 does not exceed the first temperature. Then the flue gas enters the raw material mill 14, and under the action of the raw material mill 14, the outlet temperature of the flue gas passing through the raw material mill 14 reaches below the third temperature, and directly enters the kiln tail dust collector 17.

[0078] Step 106, when the flue gas in the system flows to the high-temperature fan 4, the denitrification tower 7, the raw material mill 14 and the kiln tail dust collector 17 in sequence, the first water spray point 2 is opened to reduce the flue gas temperature from the fourth temperature to the first temperature.

[0079] Specifically, the flue gas exiting preheater 1 is at the fourth temperature. Before the flue gas enters high-temperature blower 4, first water spray point 2 is activated to lower the flue gas temperature from the fourth temperature to the first temperature, ensuring that the flue gas temperature entering high-temperature blower 4 does not exceed the first temperature. After passing through denitrification tower 7, the flue gas experiences little temperature change and then enters raw material mill 14. The flue gas's outlet temperature drops below the third temperature at the raw material mill 14, and the flue gas enters kiln tail dust collector 17 directly.

[0080] Step 107, when the flue gas in the system flows to the high-temperature fan 4 and the kiln tail dust collector 17 in sequence, first open the first water spray point 2 to reduce the flue gas temperature from the fourth temperature to the first temperature, then open the second water spray point 5 to reduce the flue gas temperature from the first temperature to the second temperature, and finally open the fourth water spray point 10 to reduce the flue gas temperature from the second temperature to the third temperature.

[0081] Specifically, the temperature of the flue gas coming out of the preheater 1 is the fourth temperature. Before the flue gas enters the high-temperature fan 4, the first water spray point 2 is opened to reduce the flue gas temperature from the fourth temperature to the first temperature, and then the second water spray point 5 is opened to reduce the temperature of the flue gas passing through the high-temperature fan 4 from the first temperature to the second temperature. Finally, the fourth water spray point 10 is opened to reduce the temperature of the flue gas passing through the fourth water spray point from the second temperature to the third temperature.

[0082] Step 108. When the flue gas in the system flows to the high-temperature fan 4, the denitrification tower 7 and the kiln tail dust collector 17 in sequence, first open the first water spray point 2 to reduce the flue gas temperature from the fourth temperature to the first temperature, then open the third water spray point 8 to reduce the flue gas temperature from the first temperature to the second temperature, and finally open the fourth water spray point 10 to reduce the flue gas temperature from the second temperature to the third temperature.

[0083] Specifically, the flue gas temperature coming out of the preheater 1 is the fourth temperature. First, the first water spray point 2 is opened. Before the flue gas enters the high-temperature fan 4, the flue gas temperature is reduced from the fourth temperature to the first temperature, ensuring that the flue gas temperature entering the high-temperature fan 4 does not exceed the first temperature. After the flue gas at the first temperature enters the denitrification tower 7, the third water spray point 8 is opened to reduce the flue gas temperature from the first temperature to the second temperature, ensuring the temperature required for the normal operation of the denitrification tower 7. Finally, the fourth water spray point 10 is opened to reduce the flue gas temperature from the second temperature to the third temperature, ensuring that the flue gas temperature entering the kiln tail dust collector 17 is not higher than the third temperature.

[0084] In the above steps 101-108, different water spraying points are set to open according to the flue gas direction in different situations, and reasonable temperature control is performed to reasonably control the water spraying amount so that the temperature meets the equipment requirements while avoiding the problem of wet bottom ash blockage caused by excessive water spraying.

[0085] In one possible embodiment, when the flue gas in the system flows in the order of waste heat boiler 3, high temperature fan 4, raw material mill 14 and kiln tail dust collector 17, and the inlet temperature of the waste heat boiler 3 exceeds the preset temperature threshold, the first water spray point 2 in the system is opened for cooling.

[0086] Specifically, when the inlet temperature of the flue gas from preheater 1 exceeds a preset temperature when entering waste heat boiler 3, first water spray point 2 is activated to cool the flue gas, ensuring that the inlet temperature of waste heat boiler 3 is at the fourth temperature. This also ensures that the flue gas does not overheat as it passes through waste heat boiler 3, high-temperature fan 4, raw material mill 14, and kiln tail dust collector 17. The preset temperature is the normal outlet temperature of preheater 1.

[0087] In a possible implementation manner, the first temperature is 220°C, the second temperature is 200°C, the third temperature is 180°C, and the fourth temperature is 320°C.

[0088] Specifically, the first temperature is the outlet temperature of the waste heat boiler 3, typically 220°C. The inlet temperature of the raw material mill 14 is also the first temperature of 220°C. The third temperature is the outlet temperature of the raw material mill 14, typically 180°C. The fourth temperature is the outlet temperature of the preheater 1, normally 320°C. The second temperature is the transition temperature between the first and third temperatures, typically 200°C. It should be noted that the specific values ​​of the first, second, third, and fourth temperatures can be adjusted according to actual production conditions.

[0089] In summary, an embodiment of the present invention provides a method for treating flue gas at the tail end of a cement kiln, comprising a waste heat boiler 3, a high-temperature fan 4, a denitrification tower 7, a raw material mill 14, a circulating fan 15, a kiln tail dust collector 17, and a tail exhaust fan 18. The system also includes a plurality of valves for controlling the opening and closing of the pipeline and a plurality of water spraying points for reducing the temperature of the flue gas in the pipeline; the inlet of the high-temperature fan 4 is connected to the outlet of the preheater 1 of the cement kiln; the flue gas treatment method can be applied to flue gas treatment under different production conditions at the tail end of the cement kiln, and the connection relationship between different equipment is reasonably set, and water spraying points and valves are set near each equipment. By adjusting the opening and closing of the valves and the opening and closing of the water spraying points, the water spraying amount is adapted to the cooling requirements of different equipment, ensuring that the flue gas temperature entering different equipment under different production conditions meets the requirements. The entire flue gas treatment system at the tail end of the cement kiln has the advantages of reducing the flue gas temperature, improving the dust removal efficiency, and reducing energy consumption.

[0090] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0091] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A cement kiln tail gas treatment system, characterized in that: The system includes a waste heat boiler, a high-temperature fan, a denitrification tower, a raw material mill, a circulating fan, a kiln tail dust collector, and a tail exhaust fan. The system also includes multiple valves for controlling the opening and closing of the pipeline and multiple water spray points for reducing the temperature of the flue gas in the pipeline; the inlet of the high-temperature fan is connected to the outlet of the cement kiln preheater; The first of the plurality of water spraying points is provided on the first pipe between the outlet of the preheater and the inlet of the high-temperature blower; the second water spraying point is provided on the second pipe between the outlet of the high-temperature blower and the inlet of the denitrification tower; the third and fourth water spraying points are provided in sequence on the third pipe between the outlet of the denitrification tower and the inlet of the kiln tail dust collector; The waste heat boiler is arranged in parallel between the outlet of the first water spraying point and the inlet of the high-temperature fan; the raw material mill and the circulating fan are arranged in parallel between the outlet of the denitrification tower and the outlet of the fourth water spraying point; the outlet of the kiln tail dust collector is connected to the inlet of the tail exhaust fan, and the outlet of the tail exhaust fan is connected to the chimney; the first valve of the multiple valves is arranged on the second pipe; the second valve and the third valve are arranged in sequence on the fourth pipe, and the fourth pipe is a pipe located between the outlet of the second water spraying point and the inlet of the raw material mill; the fourth valve is arranged on the fifth pipe, and the fifth pipe is a pipe located between the outlet of the second valve and the inlet of the fourth water spraying point; the fifth valve is arranged on the third pipe between the outlet of the third water spraying point and the inlet of the fourth water spraying point; the sixth valve is arranged on the sixth pipe, and the sixth pipe is a pipe located between the outlet of the third valve and the inlet of the third water spraying point. Each of the water spraying points is provided with at least one spray gun and an inlet and outlet temperature transmitter.

2. The system according to claim 1, wherein: The pipes described are all non-standard pipes.

3. The system according to claim 1, wherein: When the waste heat boiler is running, the denitrification tower is bypassed, and the raw material mill is running, and the second valve and the third valve are open, and the first valve, the fourth valve, and the fifth valve are closed, the flue gas in the system flows to the waste heat boiler, the high-temperature fan, the raw material mill, and the kiln tail dust collector in this order; When the waste heat boiler, the denitrification tower and the raw material mill are in operation, and the second valve, the third valve, the fourth valve and the fifth valve are closed, and the first valve and the sixth valve are opened, the flue gas in the system flows in the order of the waste heat boiler, the high-temperature fan, the denitrification tower, the raw material mill and the kiln tail dust collector.

4. The system according to claim 1, wherein: When the waste heat boiler is running, the denitrification tower and the raw material mill are bypassed, and the second valve and the fourth valve are open, and the first valve, the third valve, the fifth valve, and the sixth valve are closed, the flue gas in the system flows through the waste heat boiler, the high-temperature fan, and the kiln tail dust collector in this order; When the waste heat boiler is running, the denitrification tower is running, the raw material mill is bypassed, and the first valve and the fifth valve are open, and the second valve, the third valve, the fourth valve and the sixth valve are closed, the flue gas in the system flows in sequence to the waste heat boiler, the high-temperature fan, the denitrification tower and the kiln tail dust collector.

5. The system according to claim 1, wherein: When the waste heat boiler bypass, the denitrification tower bypass, and the raw material mill are in operation, and the second valve and the third valve are open, and the first valve, the fourth valve, the fifth valve, and the sixth valve are closed, the flue gas in the system flows to the high-temperature fan, the raw material mill, and the kiln tail dust collector in this order; When the waste heat boiler is bypassed, the denitrification tower and the raw material mill are in operation, and the first valve and the sixth valve are opened, and the second valve, the third valve, the fourth valve and the fifth valve are closed, the flue gas in the system flows to the high-temperature fan, the denitrification tower, the raw material mill and the kiln tail dust collector in sequence.

6. The system according to claim 1, wherein: When the waste heat boiler, the denitrification tower and the raw material mill are all bypassed, and the second valve and the fourth valve are opened, and the first valve, the third valve, the fifth valve and the sixth valve are closed, the flue gas in the system flows to the high-temperature fan and the kiln tail dust collector in order; When the waste heat boiler is bypassed, the denitrification tower is running, the raw material mill is bypassed, and the first valve and the fifth valve are opened, and the second valve, the third valve, the fourth valve and the sixth valve are closed, the flue gas in the system flows to the high-temperature fan, the denitrification tower and the kiln tail dust collector in sequence.

7. A method for treating flue gas from a cement kiln, characterized in that: Applied to the cement kiln tail gas treatment system according to any one of claims 1 to 6, the method comprises: When the flue gas in the system flows to the waste heat boiler, the high-temperature fan, the raw material mill and the kiln tail dust collector in sequence, and the inlet temperature of the waste heat boiler does not exceed the preset temperature threshold, each water spray point in the system is closed; When the flue gas in the system flows in the order of the waste heat boiler, the high-temperature fan, the denitrification tower, the raw material mill and the kiln tail dust collector, and the inlet temperature of the waste heat boiler does not exceed the preset temperature threshold, each water spray point in the system is closed; When the flue gas in the system flows sequentially to the waste heat boiler, the high-temperature fan, and the kiln tail dust collector, firstly open the second water spray point to reduce the flue gas temperature in the pipeline from the first temperature to the second temperature, and then open the fourth water spray point to reduce the flue gas temperature from the second temperature to the third temperature; When the flue gas in the system flows sequentially through the waste heat boiler, the high-temperature fan, the denitrification tower, and the kiln tail dust collector, firstly open the third water spray point to reduce the flue gas temperature in the pipeline from the first temperature to the second temperature, and then open the fourth water spray point to reduce the flue gas temperature from the second temperature to the third temperature; When the flue gas in the system flows sequentially toward the high-temperature fan, the raw material mill, and the kiln tail dust collector, opening the first water spray point to reduce the flue gas temperature from the fourth temperature to the first temperature; When the flue gas in the system flows sequentially to the high-temperature fan, the denitrification tower, the raw material mill, and the kiln tail dust collector, the first water spray point is opened to reduce the flue gas temperature from the fourth temperature to the first temperature; When the flue gas in the system flows sequentially toward the high-temperature fan and the kiln tail dust collector, firstly, the first water spray point is opened to reduce the flue gas temperature from the fourth temperature to the first temperature, then the second water spray point is opened to reduce the flue gas temperature from the first temperature to the second temperature, and finally, the fourth water spray point is opened to reduce the flue gas temperature from the second temperature to the third temperature; When the flue gas in the system flows in sequence to the high-temperature fan, the denitrification tower and the kiln tail dust collector, first open the first water spray point to reduce the flue gas temperature from the fourth temperature to the first temperature, then open the third water spray point to reduce the flue gas temperature from the first temperature to the second temperature, and finally open the fourth water spray point to reduce the flue gas temperature from the second temperature to the third temperature.

8. The method according to claim 7, characterized in that When the flue gas in the system flows to the waste heat boiler, the high-temperature fan, the raw material mill and the kiln tail dust collector in sequence, and the inlet temperature of the waste heat boiler exceeds the preset temperature threshold, the first water spray point in the system is opened for cooling.

9. The method according to claim 7, characterized in that The first temperature is 220°C, the second temperature is 200°C, the third temperature is 180°C, and the fourth temperature is 320°C.

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