A coal mill circulating air unit for a kiln head waste heat utilization system

Abstract

The application provides a coal mill circulating air unit for a kiln head waste heat utilization system, and belongs to the technical field of cement production. The kiln head waste heat utilization system comprises a rotary kiln, a grate cooler and a coal mill system. The inside of the grate cooler is divided into a high-temperature section, a medium-temperature section and a low-temperature section according to the gas temperature after heat exchange between gas and clinker. The medium-temperature section is connected with the coal mill system through an outlet. The coal mill circulating air unit cancels the coal mill exhaust gas exhaust chimney. The coal mill circulating air unit is connected between the coal mill system and the grate cooler. The coal mill circulating air unit comprises a coal mill dust collector, a coal mill exhaust fan and a coal air connection pipe. The coal mill dust collector and the coal mill exhaust fan are connected between the coal mill system and the grate cooler through the coal air connection pipe. The problem of how to reasonably recover and utilize the coal mill air is solved.

Description

Technical Field

[0001] This application relates to the technical field of cement production, and more specifically, to a coal mill circulating air unit for a kiln head waste heat utilization system. Background Technology

[0002] For ultra-low emission retrofitting of cement plants, air consumption at the source and exhaust emissions at the end are equally important. Only by controlling air consumption can exhaust emissions be fundamentally reduced. Excluding equipment leakage issues, the air source for rotary kiln clinker calcination comes from two sources: the grate cooler cooling fan and the burner. Reducing the air consumption at these two points is the fundamental starting point for reducing air consumption. Cement production and design should then build upon this foundation to study heat recovery or waste heat utilization.

[0003] Currently, all the air introduced by the burner enters the kiln for pulverized coal combustion, while a portion of the air introduced by the grate cooler enters the kiln for pulverized coal combustion, and the remainder is exhausted. The exhaust air is divided into three parts: first, it enters the coal mill system to dry the pulverized coal, and after purification by the dust collector, it is discharged through a separate chimney, with a flue gas temperature of 60-80℃ and an air volume accounting for approximately 6%-10% of the total air supply; second, it enters the waste heat power generation system to recover heat, and after purification by the kiln head dust collector, it is discharged, with a flue gas temperature of 90-150℃ and an air volume accounting for approximately 15%-20% of the total air supply; third, the residual air, which merges with the air from the waste heat power generation system, is directly discharged, with a flue gas temperature of 90-150℃ and an air volume accounting for approximately 25%-30% of the total air supply. In other words, about 50% of air resources are wasted, and the heat accompanying this is also emitted. This heat energy is equivalent to 5 kg of standard coal per ton of clinker. The actual capacity of a 5000t / d clinker production line is about 6000t / d. Assuming 300 operating days per year, this is equivalent to burning 9000 tons of standard coal per year.

[0004] Chinese patent publication number CN111792859 A discloses a cement production system that reduces heat loss from the kiln shell surface and eliminates enthalpy loss at the kiln head. Regarding flue gas circulation, it employs two circulation paths: first, all exhaust air from the coal mill system is treated as primary air and enters the kiln head burner, which can be called coal mill exhaust air circulation; second, all waste heat power generation air and waste air are recycled to the grate cooler, or a portion is returned to the coal mill system, which can be called waste heat power generation exhaust air circulation. This patent eliminates the coal mill chimney and kiln head chimney, only installing emergency exhaust pipes, with no external exhaust air volume under normal production conditions.

[0005] In summary, the primary purpose of air used in coal mills is to dry the moisture in raw coal, preventing moisture from entering the kiln and reducing heat loss due to heat absorption and temperature rise caused by moisture evaporation. However, in this patented method, the flue gas from the coal mill after drying is used as primary air and enters the kiln, carrying moisture into the kiln head burner. This fails to eliminate the heat loss caused by moisture, effectively negating the drying objective of the coal mill. Therefore, the existing technology for coal mill air suffers from an unreasonable recycling and utilization problem. Utility Model Content

[0006] The purpose of this application is to provide a coal mill circulating air unit for a kiln head waste heat utilization system, aiming to solve the problem of how to reasonably recover and utilize coal mill air in related technologies.

[0007] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description or may be learned by practice of this application.

[0008] According to a first aspect of this application, a coal mill circulating air unit for a kiln head waste heat recovery system is provided.

[0009] The waste heat utilization system at the kiln head includes: a rotary kiln, a grate cooler, and a coal mill system. The grate cooler is internally divided into a high-temperature section, a medium-temperature section, and a low-temperature section based on the temperature difference after heat exchange between the gas and clinker. The medium-temperature section is connected to the coal mill system via an outlet. The system is characterized by:

[0010] The coal mill circulating air unit eliminates the need for the coal mill exhaust gas chimney.

[0011] The coal mill circulating air unit is connected between the coal mill system and the grate cooler; the coal mill circulating air unit includes a coal mill dust collector, a coal mill exhaust fan and a coal-air connection pipe, and the coal mill dust collector and the coal mill exhaust fan are sequentially connected between the coal mill system and the grate cooler through the coal-air connection pipe.

[0012] In one exemplary embodiment of this application, a grate cooler air distribution box is provided between the grate cooler and the coal mill exhaust fan. The outlet of the coal mill exhaust fan is connected to the inlet of the grate cooler air distribution box through a coal-air connection pipe. The outlet of the grate cooler air distribution box is connected to the medium-temperature section of the grate cooler air distribution box through the coal-air connection pipe.

[0013] In one exemplary embodiment of this application, the air inlet end of the grate cooler air distribution box is further connected to an air inlet pipe for increasing the airflow, and the air inlet pipe can introduce airflow into the grate cooler air distribution box.

[0014] In one exemplary embodiment of this application, the gas flowing through the coal mill system contains moisture; the moisture enters the grate cooler's air distribution box after passing through the coal mill exhaust fan and the coal-air connection pipe, and then enters the medium-temperature section of the grate cooler for heat exchange.

[0015] In one exemplary embodiment of this application, the gas flowing through the coal mill system contains coal dust. The coal mill dust collector of the coal mill circulating air unit can filter out part of the coal dust in the gas. The remaining coal dust enters the grate cooler air box after passing through the coal mill exhaust fan and the coal air connection pipe, and then enters the grate cooler for recycling.

[0016] In one exemplary embodiment of this application, the coal-air connection pipe includes a first connection pipe, a second connection pipe, a third connection pipe, a fourth connection pipe, and a fifth connection pipe; the first connection pipe is connected between the medium-temperature section of the grate cooler and the coal mill system; the second connection pipe is connected between the coal mill system and the coal mill dust collector; the third connection pipe is connected between the coal mill dust collector and the coal mill exhaust fan; the fourth connection pipe is connected between the coal mill exhaust fan and the grate cooler air collector; and the fifth connection pipe is connected between the grate cooler air collector and the medium-temperature section of the grate cooler.

[0017] In one exemplary embodiment of this application, an intake fan is also included, which is mounted on the fifth connecting pipe.

[0018] In one exemplary embodiment of this application, a coal mill air circulation valve is also included, which is installed on the fourth pipe fitting.

[0019] In one exemplary embodiment of this application, a coal powder collecting device is also included. The coal powder collecting device is disposed below the discharge port of the coal mill dust collector and is used to collect the coal powder filtered by the coal powder dust collector.

[0020] In one exemplary embodiment of this application, the pulverized coal collecting device is configured as a pulverized coal conveyor.

[0021] The exemplary embodiments of this application may have some or all of the following beneficial effects:

[0022] The coal mill circulating air unit for a kiln head waste heat utilization system provided in the example embodiment of this application introduces a portion of the gas from the intermediate temperature section of the grate cooler into the coal mill system to form coal mill air for its use. This fully utilizes the heat in the intermediate temperature section of the grate cooler. After the coal mill system discharges the used coal mill air, it is filtered by a coal mill dust collector, and then a coal mill exhaust fan guides the coal mill air back to the intermediate temperature section of the grate cooler. The recovered coal mill air, upon entering the grate cooler, absorbs heat through evaporation due to the moisture it carries, further accelerating the cooling of the clinker and thus improving the cooling efficiency of the intermediate temperature section of the grate cooler. In summary, circulating coal mill air to the grate cooler through the coal mill circulating air unit not only avoids heat loss from the kiln head burner but also improves the cooling efficiency of the grate cooler for clinker. Therefore, the coal mill circulating air unit in this application can reasonably recover and utilize coal mill air.

[0023] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0024] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0025] Figure 1 This document illustrates a flow chart of a coal mill circulating air unit for a kiln head waste heat utilization system, as described in an embodiment of this application.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1. Rotary kiln; 2. Grate cooler; 3. Clinker conveyor; 4. Clinker silo; 5. Coal mill system; 6. Waste heat boiler; 7. Kiln head dust collector; 8. Kiln head exhaust fan; 9. Kiln head chimney; 10. Coal mill dust collector; 11. Coal mill exhaust fan; 13. Pulverized coal conveyor; 14. Kiln tail pulverized coal silo; 15. Kiln head pulverized coal silo; 16. Kiln tail pulverized coal scale; 17. Kiln head pulverized coal scale; 18. Decomposition furnace; 19. Kiln head burner; 20. Kiln tail coal... 21. Pulverized coal standby blower; 22. Kiln head pulverized coal blower; 23, 24. Kiln head primary air blower; 25, 26, 27, 28, 35, 36. Cooling fan; 29-34. Intake fan; 37. Grate cooler air distribution box; 37-1. Waste heat power generation air circulation valve; 37-2. Coal mill air circulation valve; 38. Pulverized coal conveying air distribution box; 38-1. Air inlet valve; 38-2. Pulverized coal conveying air inlet valve. Detailed Implementation

[0028] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this application will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore their detailed descriptions will be omitted. Furthermore, the drawings are merely illustrative of this application and are not necessarily drawn to scale.

[0029] Although relative terms such as "upper" and "lower" are used in this specification to describe the relative relationship of one component of an icon to another, these terms are used only for convenience, such as according to the orientation of the examples in the accompanying drawings. It is understood that if the device of the icon is flipped so that it is upside down, the component described as "upper" will become the component described as "lower." When a structure is "upper" of another structure, it may mean that the structure is integrally formed on the other structure, or that the structure is "directly" mounted on the other structure, or that the structure is "indirectly" mounted on the other structure through another structure.

[0030] The terms “a,” “one,” “the,” and “at least one” are used to indicate the existence of one or more elements / components / etc.; the terms “including” and “having” are used to indicate an open-ended inclusion and to mean that there may be other elements / components / etc. in addition to the listed elements / components / etc.; the terms “first” and “second” are used only as markers and are not a limitation on the number of objects.

[0031] Reference Figure 1 In this embodiment of the application, a waste heat utilization system for kiln head is provided, including a rotary kiln 1, a grate cooler 2, a coal mill system 5, and a waste heat boiler 6.

[0032] Furthermore, the rotary kiln 1 includes a cylinder, a kiln head burner 19, and a decomposition furnace 18; the grate cooler 2 is divided into a high-temperature section, a medium-temperature section, and a low-temperature section according to the temperature after heat exchange between the gas and clinker. The high-temperature gas in the high-temperature section enters the cylinder and the decomposition furnace 18 as secondary and tertiary air, respectively. The medium-temperature section is connected to the coal mill system 5 and the waste heat boiler 6 through an outlet. In this application, the gas entering the waste heat boiler 6 from the medium-temperature section of the grate cooler 2 can be called waste heat power generation air, and the gas entering the coal mill system 5 from the medium-temperature section of the grate cooler 2 can be called coal mill air.

[0033] The kiln head waste heat utilization system also includes a grate cooler air distribution box 37, a coal mill circulating air unit, and a waste heat power generation air circulation unit.

[0034] In this embodiment, the coal mill circulating air unit eliminates the need for the coal mill exhaust gas discharge chimney;

[0035] The outlet of the grate cooler air distribution box 37 is connected to the inlet of the medium temperature section of the grate cooler 2;

[0036] One end of the coal mill circulating air unit is connected to the outlet of the coal mill system 5, and the other end is connected to the inlet of the grate cooler air collector 37; the coal mill circulating air unit is configured such that the gas entering the coal mill system 5 enters the grate cooler air collector 37 for recycling after passing through the coal mill circulating air unit;

[0037] The waste heat power generation air circulation unit includes at least a first waste heat power generation air sub-circulation unit. The first waste heat power generation air sub-circulation unit is configured such that a portion of the gas entering the waste heat boiler 6 enters the grate cooler air distribution box 37 for recycling.

[0038] In this embodiment, the grate cooler 2 introduces air from the outside into its interior during the high-temperature section to cool the clinker inside. A portion of the gas in the intermediate-temperature section of the grate cooler 2 enters the coal mill system 5, while another portion enters the waste heat boiler 6 for use. This process effectively utilizes the heat from the intermediate-temperature section of the grate cooler 2. The waste heat boiler 6 uses the heat energy from the intermediate-temperature section of the grate cooler 2 for power generation or heating, reducing external energy demand. The coal mill system 5 recovers heat energy to accelerate the evaporation of moisture from the raw coal, drying the produced coal powder. Furthermore, it reduces direct heat emissions, lowering thermal pollution to the environment.

[0039] In this embodiment, after the coal mill system 5 discharges the used gas, it is then sent to the grate cooler air collector 37 via the coal mill circulation air unit. In the prior art, the coal mill system 5 typically discharges the gas directly through the coal mill chimney. Compared to the prior art, the kiln head waste heat utilization system disclosed in this application eliminates the coal mill chimney used for discharging coal mill waste gas. Instead, it guides all the coal mill waste gas into the grate cooler air collector 37, and then from the grate cooler air collector 37, it guides it into the medium-temperature section of the grate cooler 2 for recycling. Therefore, this system can recycle all the coal mill waste gas discharged from the coal mill system 5 without discharging it, effectively reducing resource waste and providing good environmental protection by reducing pollution.

[0040] In this application, the coal mill circulating air unit includes a coal mill dust collector 10, a coal mill exhaust fan 11, a coal mill circulating air valve 37-2, and a coal-air connection pipe; the coal mill dust collector 10, the coal mill exhaust fan 11, and the coal mill circulating air valve 37-2 are sequentially connected between the coal mill system 5 and the grate cooler air collection box 37 through the coal-air connection pipe.

[0041] In this embodiment, the coal-air connection pipe includes a first connection pipe, a second connection pipe, a third connection pipe, a fourth connection pipe, and a fifth connection pipe; the first connection pipe is connected between the medium-temperature section of the grate cooler and the coal mill system; the second connection pipe is connected between the coal mill system and the coal mill dust collector; the third connection pipe is connected between the coal mill dust collector and the coal mill exhaust fan; the fourth connection pipe is connected between the coal mill exhaust fan and the grate cooler air collector; the fifth connection pipe is connected between the grate cooler air collector and the medium-temperature section of the grate cooler; and a coal mill air circulation valve 37-2 is installed on the fourth connection pipe.

[0042] In this application, when preparing pulverized coal, the coal mill system 5 introduces heat energy from the grate cooler 2 into the coal mill system 5 through a first connecting pipe. The coal mill system 5 dries the pulverized coal to remove moisture. The gas discharged from the coal mill system 5 carries the moisture evaporated from the pulverized coal. The gas, moisture, and pulverized coal are introduced into the coal mill dust collector 10 through a second connecting pipe. The coal mill dust collector 10 is used to collect some of the pulverized coal dust generated by the coal mill system 5. Since the coal mill dust collector 10 needs to allow gas to pass through and be discharged, and the pulverized coal dust cannot obstruct the gas flow, the coal mill dust collector 10 can only filter out most of the pulverized coal in the gas, leaving a small portion that cannot be completely filtered out. In the prior art, the pulverized coal discharged from the coal mill dust collector 10 is directly discharged through the coal mill chimney, which not only wastes energy but also causes environmental pollution.

[0043] In this embodiment, the gas discharged from the coal mill dust collector 10 is transported to the coal mill exhaust fan 11 via the third connecting pipe, and continues to be discharged through the coal mill exhaust fan 11. The exhaust end of the coal mill exhaust fan 11 is connected to the grate cooler air collector 37 via the fourth connecting pipe. In this application, the gas discharged from the coal mill circulating air unit to the grate cooler air collector 37 is called the coal mill circulating airflow; the coal mill circulating airflow will carry moist coal dust formed by the mixture of moisture and coal powder.

[0044] After the coal mill's circulating airflow enters the grate cooler's air distribution box 37, it is discharged into the intermediate temperature section of the grate cooler 2 through the fifth connecting pipe. The mixed airflow discharged into the grate cooler 2 will carry moist coal dust. In the intermediate temperature section of the grate cooler 2, the coal dust carried by the airflow will first be dried, causing the moisture to evaporate, thereby absorbing a large amount of heat and improving the cooling effect on the clinker. As the airflow flows within the grate cooler 2, the coal dust also rises continuously. The heat from the grate cooler 2 will cause the coal dust to burn when it enters the waste heat boiler 6 and the coal mill system 5, thereby increasing the temperature of the waste heat power generation air and the coal mill air, and thus improving the thermal utilization rate of the waste heat boiler 6 and the coal mill system 5.

[0045] In summary, reintroducing the circulating airflow from the coal mill into the medium-temperature section of the grate cooler 2 not only improves the cooling effect of the grate cooler 2 on the clinker, but also heats the gas used in the waste heat boiler 6 and the coal mill system 5, thereby increasing the thermal utilization rate of both. More importantly, it allows coal dust that the coal mill dust collector 10 failed to filter to be reintroduced into the grate cooler 2 for combustion instead of being released into the atmosphere, thus protecting the environment.

[0046] In this embodiment, the kiln head waste heat utilization system further includes an air intake unit, a waste heat power generation exhaust system, and a clinker conveying unit.

[0047] The air intake unit includes a grate cooler air distribution box 37, cooling fans 25-36, and connecting pipes; cooling fans 25-28 are located in the high-temperature section of the grate cooler 2 and are used to supply air to the high-temperature section of the grate cooler 2; cooling fans 29-34 are located in the medium-temperature section of the grate cooler 2 and are used to supply the mixed airflow from the grate cooler air distribution box 37 to the medium-temperature section of the grate cooler 2; cooling fans 35 and 36 are located in the low-temperature section of the grate cooler 2 and are used to supply air to the low-temperature section of the grate cooler 2.

[0048] In this embodiment, the first waste heat power generation air circulation unit includes a kiln head dust collector 7, a kiln head exhaust fan 8, and a waste heat power generation air circulation valve 37-1.

[0049] The kiln head dust collector 7, the kiln head exhaust fan 8, and the waste heat power generation air circulation valve 37-1 are connected in sequence between the outlet of the waste heat boiler 6 and the inlet of the grate cooler air collector box 37 via connecting pipes.

[0050] In this embodiment, the gas that enters the grate cooler's air collection box 37 for circulation after passing through the first waste heat power generation air circulation unit is called the waste heat power generation circulating airflow. Specifically, the gas discharged from the intermediate temperature section of the grate cooler 2 enters the waste heat boiler 6 for its use, and then exits from the waste heat boiler 6. After being filtered by the kiln head dust collector 7, a portion of the gas is discharged to the grate cooler's air collection box 37 by the kiln head exhaust fan 8. The gas discharged into the grate cooler's air collection box 37 is the waste heat power generation circulating airflow. The waste heat power generation circulating airflow and the coal mill circulating airflow merge in the grate cooler's air collection box 37 before being discharged into the intermediate temperature section of the grate cooler 2.

[0051] In this embodiment, the grate cooler air distribution box 37 is also connected to an air inlet pipe. Airflow is introduced into the grate cooler air distribution box 37 through the air inlet pipe, merging with the coal mill circulating airflow. The airflow is then introduced into the intermediate temperature section of the grate cooler via a fifth connecting pipe. An air intake fan 29-34 is installed on the fifth connecting pipe to accelerate the mixing of the airflow into the intermediate temperature section of the grate cooler. This application does not impose any special restrictions on the number of fifth connecting pipes and air intake fans 29-34.

[0052] It is understood that in this application, the air circulation unit for the first waste heat power generation is introduced into the grate cooler air receiver box 37 through the air intake pipe. That is to say, in this application, the air intake pipe is used to introduce the waste heat power generation circulating airflow. Of course, this is not limiting; the air intake pipe can also be directly connected to the outside to introduce outside air into the grate cooler air receiver box 37.

[0053] In this embodiment, the kiln head waste heat utilization system further includes a pulverized coal conveying unit. Specifically, the pulverized coal conveying unit includes: a pulverized coal conveyor 13, a kiln tail pulverized coal silo 14, a kiln head pulverized coal silo 15, a kiln tail pulverized coal scale 16, a kiln head pulverized coal scale 17, a pulverized coal conveying air distribution box 38, a kiln tail pulverized coal blower 20, a standby pulverized coal blower 21, a kiln head pulverized coal blower 22, a kiln head burner 19, and connecting pipe fittings.

[0054] The coal powder flow is as follows: After being ground into powder by the coal mill system 5, the raw coal is collected by the coal mill dust collector 10 and fed into the kiln tail coal powder bin 14 and the kiln head coal powder bin 15 respectively by the coal powder conveyor 13. The kiln tail coal powder is metered by the kiln tail coal powder scale 16 and then enters the decomposition furnace 18 with the air. The kiln head coal powder is metered by the kiln head coal powder scale 17 and then enters the kiln head burner 19 with the air.

[0055] In this embodiment, a coal mill dust collector is provided below the coal mill dust collector 10. The coal mill dust collector can collect and recycle the coal powder filtered by the coal mill dust collector 10, thereby avoiding the waste of coal powder. In this application, the coal powder dust collector is set as a coal powder conveyor 13. The coal powder can be directly introduced into the kiln tail coal powder bin 14 or the kiln head coal powder bin 15 through the coal powder conveyor 13 without human intervention, thus providing convenience for the staff.

[0056] In this embodiment, the waste heat power generation wind circulation unit further includes a second waste heat power generation wind sub-circulation unit. The second waste heat power generation wind sub-circulation unit is configured such that a portion of the gas entering the waste heat boiler 6 enters the pulverized coal conveying unit via the second waste heat power generation wind sub-circulation unit and then enters the rotary kiln 1 and the decomposition furnace 18 along with the pulverized coal.

[0057] Furthermore, the second residual wind power generation wind sub-circulation unit includes an air intake valve 38-1, a pulverized coal conveying air intake valve 38-2, a pulverized coal conveying air distribution box 38, a kiln tail pulverized coal blower 20, and a kiln head pulverized coal blower 22.

[0058] Furthermore, the air intake valve 38-1 is connected to the inlet of the pulverized coal conveying air distribution box 38. Opening the air intake valve 38-1 allows outside air to enter the pulverized coal conveying air distribution box 38. One end of the pulverized coal conveying air intake valve 38-2 is connected to the outlet of the kiln head exhaust fan 8 via a connecting pipe, and the other end is connected to the inlet of the pulverized coal conveying air distribution box 38. One end of the kiln tail pulverized coal blower 20 is connected to the outlet of the pulverized coal conveying air distribution box 38 via a connecting pipe, and the other end is connected to the decomposition furnace 18 via the kiln tail pulverized coal scale 16 via a connecting pipe. One end of the kiln head pulverized coal blower 22 is connected to the outlet of the pulverized coal conveying air distribution box 38 via a connecting pipe, and the other end is connected to the kiln head burner 19 via the kiln head pulverized coal scale 17 via a connecting pipe.

[0059] Furthermore, the second residual wind power generation sub-circulation unit also includes a pulverized coal standby blower 21, a three-way pipe, and air valves. The three-way pipe includes one main pipe and two branch pipes. The main pipe is connected to the exhaust end of the pulverized coal standby blower 21, one branch pipe is connected to the connecting pipe at the exhaust end of the kiln head pulverized coal blower 22, and the other branch pipe is connected to the connecting pipe at the exhaust end of the kiln tail pulverized coal blower 20. Two air valves are provided, installed on the two branch pipes. The pulverized coal standby blower 21 achieves a "two-for-one" effect. When the kiln tail pulverized coal blower 20 or the kiln head pulverized coal blower 22 fails, the pulverized coal standby blower 21 can be started and the corresponding air valve opened to continue operation.

[0060] Specifically, the kiln head exhaust fan 8 discharges part of the gas to the pulverized coal conveying air collector 38, which mixes this gas with the outside air before discharging it. The discharged gas is called the pulverized coal conveying airflow. Part of the pulverized coal conveying airflow flows to the kiln tail pulverized coal scale 16 through connecting pipes, and the other part flows to the kiln head pulverized coal scale 17 through connecting pipes. The airflow flowing to the kiln tail pulverized coal scale 16 is called the kiln tail airflow, and the airflow flowing to the kiln head pulverized coal scale 17 is called the kiln head airflow. The kiln tail airflow guides the pulverized coal on the kiln tail pulverized coal scale 16 into the decomposition furnace 18, and the kiln head airflow guides the pulverized coal on the kiln head pulverized coal scale 17 into the kiln head burner 19.

[0061] In this embodiment of the application, the waste heat power generation air circulation unit further includes a third waste heat power generation air sub-circulation unit. The third waste heat power generation air sub-circulation unit is configured such that a portion of the gas entering the waste heat boiler 6 enters the kiln head burner 19 via the third waste heat power generation air sub-circulation unit as primary air.

[0062] Furthermore, the third waste air power generation sub-circulation unit is connected between the kiln head exhaust fan 8 and the primary air inlet of the kiln head burner 19. The third waste air power generation sub-circulation unit includes kiln head primary air fans 23 and 24 and connecting pipes. One end of each kiln head primary air fan 23 and 24 is connected to the outlet of the kiln head exhaust fan 8 via a connecting pipe, and the other end is connected to the primary air inlet of the kiln head burner 19 via a connecting pipe. In this application, two kiln head primary air fans 23 and 24 are configured, with one fan in operation and one in reserve. During operation, only one kiln head primary air fan 23 is started. If the operating kiln head primary air fan 23 fails, the other reserve kiln head primary air fan 24 can be started.

[0063] In this embodiment, the waste heat power generation exhaust system includes a kiln head chimney 9 and connecting pipes, wherein the kiln head chimney 9 is connected to the kiln head exhaust fan 8 via the connecting pipes.

[0064] The residual gas after the gas entering the waste heat boiler is distributed by the first waste heat power generation wind circulation unit, the second waste heat power generation wind circulation unit and the third waste heat power generation wind circulation unit is waste gas, which is discharged into the kiln head chimney 9.

[0065] Therefore, in summary, the airflow direction in the kiln head waste heat utilization system of this application is as follows:

[0066] In addition to outside air, the cooling air source for the grate cooler 2 includes two additional sources: the circulating airflow from the coal mill and the circulating airflow from the waste heat power generation system. These two airflows enter the grate cooler 2 after passing through the grate cooler air collector 37. After heat exchange between the gas and clinker inside the grate cooler 2, the high-temperature gas enters the rotary kiln 1 and the decomposition furnace 18 as secondary and tertiary air, respectively. The medium-temperature gas enters the coal mill system 5 and the waste heat boiler 6, respectively. The low-temperature gas enters the kiln head dust collector 7 and is discharged after purification. The gas entering the coal mill system 5 forms a coal mill circulating airflow after passing through the coal mill air circulation unit. The coal mill circulating airflow enters the grate cooler air collector 37 for recycling. The gas entering the waste heat boiler 6 forms a waste heat power generation circulating airflow after passing through the waste heat power generation air circulation unit. It enters the grate cooler air collector 37 for recycling. Another part enters the pulverized coal conveying unit to form a pulverized coal conveying airflow. Then, the pulverized coal conveying airflow forms a kiln head airflow flowing to the kiln head pulverized coal scale 17 and a kiln tail airflow flowing to the kiln tail pulverized coal scale 16 through connecting pipes. The kiln head airflow enters the kiln head burner 19 with the pulverized coal, and the kiln tail airflow enters the decomposition furnace 18 with the pulverized coal. Another part enters the kiln head burner 19 as primary air. The remaining air is purified by the kiln head dust collector 7 and then discharged by the kiln head exhaust fan 8 to the kiln head chimney 9 for external discharge.

[0067] In this embodiment, the kiln head waste heat utilization system further includes a clinker conveying unit, which comprises a clinker conveyor 3 and a clinker silo 4. In this application, the clinker flow is as follows: high-temperature clinker, after processing in the rotary kiln 1, directly enters the grate cooler 2. The grate cooler 2 moves the clinker away from the rotary kiln 1. During this movement, the clinker exchanges heat with the airflow, causing its temperature to continuously decrease. The interior of the grate cooler 2 is divided into a high-temperature section, a medium-temperature section, and a low-temperature section according to the clinker temperature along the direction away from the rotary kiln 1. Specifically, the temperature range of the high-temperature section is approximately 1200℃ to 1000℃; the temperature range of the medium-temperature section is approximately 1000℃ to 600℃; and the temperature range of the low-temperature section is below 600℃. The discharge end of the grate cooler 2 is located away from the rotary kiln 1. The cooled clinker is discharged from the discharge end of the grate cooler 2 and transported to the clinker silo 4 by the clinker conveyor 3.

[0068] In this embodiment, the low-temperature section of the grate cooler 2 has an outlet. The low-temperature gas from this section merges with the gas from the outlet of the waste heat boiler 6 through the outlet and connecting pipes before entering the kiln head dust collector 7. These gases typically contain a certain amount of heat, and although their temperature is low, they can still be recovered and reused. The gas from the outlet of the waste heat boiler 6 is typically at a higher temperature. Mixing it with the gas from the low-temperature section of the grate cooler 2 helps to balance the gas temperature, preventing damage to the kiln head dust collector 7 due to excessively high temperatures. Therefore, recovering the gas from the low-temperature section of the grate cooler 2 not only increases the volume of air recovered but also protects the kiln head dust collector 7.

[0069] In this embodiment, the clinker conveyor 3 is connected to the outlet of the waste heat boiler 6 via connecting pipes after the clinker leaves the low-temperature section of the grate cooler 2. Specifically, a dust collection hood is installed above the clinker conveyor 3, located near the outlet of the grate cooler 2. When the clinker falls onto the clinker conveyor 3, the floating clinker dust and the heat emitted by the clinker can be transported through the dust collection hood and connecting pipes to merge with the gas at the outlet of the waste heat boiler 6. The gas then passes through the kiln head dust collector 7 for filtration. This process filters and recovers the floating clinker, reducing clinker waste and protecting the surrounding environment. Furthermore, it increases the amount of heat recovered. Those skilled in the art will readily conceive of other embodiments of this application upon considering the specification and practicing the embodiments of this application. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not claimed in this application. The description and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the appended claims.

Claims

1. A coal mill circulating air unit for a kiln head waste heat utilization system, characterized in that, The waste heat utilization system at the kiln head includes a rotary kiln, a grate cooler, and a coal mill system. The grate cooler is divided into a high-temperature section, a medium-temperature section, and a low-temperature section according to the temperature after heat exchange between the gas and clinker. The medium-temperature section is connected to the coal mill system through an outlet. The coal mill circulating air unit eliminates the need for the coal mill exhaust gas chimney. The coal mill circulating air unit is connected between the coal mill system and the grate cooler; the coal mill circulating air unit includes a coal mill dust collector, a coal mill exhaust fan and a coal-air connection pipe, and the coal mill dust collector and the coal mill exhaust fan are sequentially connected between the coal mill system and the grate cooler through the coal-air connection pipe.

2. The coal mill circulating air unit for a kiln head waste heat utilization system according to claim 1, characterized in that, A grate cooler air distribution box is provided between the grate cooler and the coal mill exhaust fan. The outlet of the coal mill exhaust fan is connected to the inlet of the grate cooler air distribution box through a coal air connection pipe. The outlet of the grate cooler air distribution box is connected to the medium temperature section of the grate cooler air distribution box through the coal air connection pipe.

3. The coal mill circulating air unit for a kiln head waste heat utilization system according to claim 2, characterized in that, The air inlet of the grate cooler air distribution box is also connected to an air inlet pipe for increasing airflow, which can introduce airflow into the grate cooler air distribution box.

4. A coal mill circulating air unit for a kiln head waste heat utilization system according to claim 2, characterized in that, The gas flowing through the coal mill system contains moisture; the moisture enters the grate cooler's air distribution box after passing through the coal mill exhaust fan and the coal-air connection pipe, and then enters the medium-temperature section of the grate cooler for heat exchange.

5. A coal mill circulating air unit for a kiln head waste heat utilization system according to claim 4, characterized in that, The gas flowing through the coal mill system contains coal dust. The coal mill dust collector of the coal mill circulating air unit can filter out some of the coal dust in the gas. The remaining coal dust enters the grate cooler air box after passing through the coal mill exhaust fan and the coal air connection pipe, and then enters the grate cooler for recycling.

6. A coal mill circulating air unit for a kiln head waste heat utilization system according to any one of claims 2-5, characterized in that, The coal-air connection pipe includes a first connection pipe, a second connection pipe, a third connection pipe, a fourth connection pipe, and a fifth connection pipe; the first connection pipe is connected between the medium-temperature section of the grate cooler and the coal mill system; the second connection pipe is connected between the coal mill system and the coal mill dust collector; the third connection pipe is connected between the coal mill dust collector and the coal mill exhaust fan; the fourth connection pipe is connected between the coal mill exhaust fan and the grate cooler air collector; and the fifth connection pipe is connected between the grate cooler air collector and the medium-temperature section of the grate cooler.

7. A coal mill circulating air unit for a kiln head waste heat utilization system according to claim 6, characterized in that, It also includes an intake fan, which is installed on the fifth connecting pipe.

8. A coal mill circulating air unit for a kiln head waste heat utilization system according to claim 6, characterized in that, It also includes a coal mill air circulation valve, which is installed on the fourth connecting pipe.

9. A coal mill circulating air unit for a kiln head waste heat utilization system according to claim 1, characterized in that, It also includes a coal dust collection device, which is located below the discharge port of the coal mill dust collector and is used to collect the coal dust filtered by the coal dust collector.

10. A coal mill circulating air unit for a kiln head waste heat utilization system according to claim 9, characterized in that, The coal powder collection equipment is configured as a coal powder conveyor.

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