Kiln head waste heat utilization system

Abstract

The application provides a kiln head waste heat utilization system, relates to the cement production technical field, and comprises a rotary kiln, a grate cooler, a coal mill system, a waste heat boiler and a pulverized coal conveying unit. The inside of the grate cooler is divided into a medium temperature section and a low temperature section according to the gas temperature after gas and clinker heat exchange. The kiln head waste heat utilization system further comprises a coal mill circulating air unit and a waste heat power generation air circulating unit. The kiln head waste heat utilization system cancels the coal mill exhaust gas discharge coal mill chimney. The coal mill circulating air unit is connected between the coal mill system and the medium temperature section of the grate cooler. The gas entering the coal mill system is circulated and used in the grate cooler after the coal mill circulating air unit. The waste heat power generation air circulating unit at least comprises a first waste heat power generation air sub-circulating unit. Part of the gas entering the waste heat boiler is circulated and used in the grate cooler after the first waste heat power generation air sub-circulating unit. The effect of reducing air consumption, reducing waste gas emission and recovering waste gas waste heat is realized.

Description

Technical Field

[0001] This application relates to the field of cement production technology, and more specifically, to 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] The Chinese patent publication number "CN111792859 A" discloses "a cement production system that reduces heat loss on the surface of the kiln cylinder and eliminates enthalpy loss at the kiln head". In terms of flue gas circulation, there are two circulation paths. One is to use the exhaust air of the coal mill system as primary air and enter the kiln head burner, which can be called coal mill air circulation. The other is to use the waste heat power generation air and waste air as grate cooler, or to return a portion to the coal mill system, which can be called waste heat power generation air circulation. This patent eliminates the coal mill chimney and the kiln head chimney and only sets up an emergency exhaust pipe. Under normal production, there is no external exhaust air volume, so the following problems exist: (1) The main purpose of the coal mill air is to dry the moisture in the raw coal, avoid moisture entering the kiln, and reduce the heat loss caused by moisture evaporation and heating. However, the flue gas after coal mill drying in this patent is used as primary air to enter the kiln, which will bring the moisture into the kiln head burner. It does not eliminate the heat loss caused by moisture, which is equivalent to the drying purpose of the coal mill not being achieved. (2) The waste heat power generation air is recycled to cool the clinker in the medium temperature section of the grate cooler. In contrast, the temperature of the flue gas at the grate cooler inlet rises and the temperature of the clinker also rises. In order to ensure that the temperature of the clinker exiting the kiln does not rise and the temperature of the waste heat power generation inlet does not decrease, it is necessary to increase the amount of cold air mixed in the low temperature section of the grate cooler. In other words, there must be waste air discharged. The flue gas cannot be infinitely closed-looped, the kiln head chimney cannot be eliminated, and the enthalpy cannot be completely recovered.

[0005] The utility model patent with Chinese patent publication number "202121990447.X" discloses "a waste heat recovery system for a grate cooler with full circulation of waste air". Strictly speaking, it is a waste heat power generation air circulation system, but it does not consider the air circulation for coal mills. It also has the problem that the cold air volume needs to be increased in the low-temperature section of the grate cooler, which inevitably results in the exhaust of waste air and cannot achieve the purpose of full circulation of waste air.

[0006] In conclusion, it is impossible to fully recover and utilize all the wind used for waste heat power generation. Therefore, it is an urgent problem to be solved to fully utilize flue gas recirculation to reduce air consumption, reduce exhaust emissions, and recover waste heat from exhaust gases. Utility Model Content

[0007] The purpose of this application is to provide a kiln head waste heat utilization system, which aims to solve the problems of how to reduce air consumption, reduce waste gas emissions, and recover waste heat from waste gas.

[0008] 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.

[0009] According to a first aspect of this application, a kiln head waste heat utilization system is provided, including a rotary kiln, a grate cooler, a coal mill system, a waste heat boiler, and a pulverized coal conveying unit. The rotary kiln includes a cylinder, a kiln head burner, and a decomposition furnace. The grate cooler is divided into a medium-temperature section and a low-temperature section according to the air temperature after heat exchange between the gas and clinker.

[0010] The kiln head waste heat utilization system also includes a coal mill circulating air unit and a waste heat power generation air circulation unit. The kiln head waste heat utilization system eliminates the coal mill exhaust gas discharge from the coal mill chimney.

[0011] The coal mill circulating air unit is connected between the coal mill system and the medium temperature section of the grate cooler; the coal mill circulating air unit is configured such that the gas entering the coal mill system enters the grate cooler for circulation after passing through the coal mill circulating air unit;

[0012] The waste heat power generation air circulation unit includes at least a first waste heat power generation air sub-circulation unit, which is configured such that a portion of the gas entering the waste heat boiler is circulated within the grate cooler via the first waste heat power generation air sub-circulation unit.

[0013] In one exemplary embodiment of this application, the coal mill circulating air unit includes a coal mill dust collector, a coal mill exhaust fan, a coal mill circulating air valve, and connecting pipes. The coal mill dust collector, the coal mill exhaust fan, and the coal mill circulating air valve are sequentially connected between the coal mill system and the grate cooler through the connecting pipes.

[0014] In one exemplary embodiment of this application, the gas flowing through the coal mill system contains coal dust and moisture; the coal mill dust collector of the coal mill circulating air unit can filter out part of the coal dust in the gas, and the remaining coal dust enters the grate cooler for recycling after passing through the coal mill exhaust fan, the coal mill circulating air valve and corresponding connecting pipes; the moisture enters the medium temperature section of the grate cooler for heat exchange after passing through the coal mill exhaust fan, the coal mill circulating air valve and corresponding connecting pipes.

[0015] In one exemplary embodiment of this application, the waste heat power generation wind circulation unit further includes a second waste heat power generation wind sub-circulation unit and a third waste heat power generation wind sub-circulation unit;

[0016] The second waste heat power generation air circulation unit is configured such that a portion of the gas entering the waste heat boiler enters the pulverized coal conveying unit via the second waste heat power generation air circulation unit and then enters the rotary kiln and the decomposition furnace along with the pulverized coal.

[0017] The third waste heat power generation air circulation unit is configured such that a portion of the gas entering the waste heat boiler enters the kiln head burner via the third waste heat power generation air circulation unit and is used as primary air.

[0018] In one exemplary embodiment of this application, the first waste heat power generation air circulation unit includes a kiln head dust collector, a kiln head exhaust fan, a waste heat power generation air circulation valve, and connecting pipes. The kiln head dust collector, the kiln head exhaust fan, and the waste heat power generation air circulation valve are sequentially connected between the outlet of the waste heat boiler and the inlet of the grate cooler through the connecting pipes.

[0019] In one exemplary embodiment of this application, the second waste wind power generation wind sub-circulation unit is connected between the kiln head exhaust fan and the kiln head burner;

[0020] The second exhaust wind power generation circulation unit includes an air intake valve, a pulverized coal conveying intake valve, a pulverized coal conveying air distribution box, a kiln tail pulverized coal blower, a kiln head pulverized coal blower, and connecting pipes. The air intake valve is connected to the inlet of the pulverized coal conveying air distribution box. One end of the pulverized coal conveying intake valve is connected to the outlet of the kiln head exhaust fan via a connecting pipe, and the other end is connected to the inlet of the pulverized coal conveying air distribution box. One end of the kiln tail pulverized coal blower is connected to the outlet of the pulverized coal conveying air distribution box via a connecting pipe, and the other end is connected to the decomposition furnace via a kiln tail pulverized coal scale via a connecting pipe. One end of the kiln head pulverized coal blower is connected to the outlet of the pulverized coal conveying air distribution box via a connecting pipe, and the other end is connected to the kiln head burner via a kiln head pulverized coal scale via a connecting pipe.

[0021] In one exemplary embodiment of this application, the third residual wind power generation wind sub-circulation unit is connected between the kiln head exhaust fan and the primary air inlet of the kiln head burner;

[0022] The third residual wind power generation air circulation unit includes a kiln head primary air fan and connecting pipes. One end of the kiln head primary air fan is connected to the outlet of the kiln head exhaust fan through the connecting pipes, and the other end is connected to the primary air inlet of the kiln head burner through the connecting pipes.

[0023] In one exemplary embodiment of this application, a waste heat power generation exhaust system is also included, the waste heat power generation exhaust system including a kiln head chimney and connecting pipes, the kiln head chimney being connected to the kiln head exhaust fan via the connecting pipes;

[0024] The gas entering the waste heat boiler is distributed by the first waste heat power generation air circulation unit, the second waste heat power generation air circulation unit and the third waste heat power generation air circulation unit, and the remaining gas is discharged from the kiln head chimney.

[0025] In one exemplary embodiment of this application, the low-temperature section of the grate cooler has an outlet, and the low-temperature gas in the low-temperature section merges with the gas from the waste heat boiler outlet through the outlet and connecting pipes before entering the kiln head dust collector.

[0026] In one exemplary embodiment of this application, a clinker conveying unit is further included. The clinker conveying unit includes a clinker conveyor, a clinker silo, and connecting pipes. After the clinker inside the grate cooler exchanges heat with the gas, the clinker falls onto the clinker conveyor and is transported by the clinker conveyor to the clinker silo for storage. The temperature of the clinker decreases during the transport process by the clinker conveyor. The connecting pipe is located above the clinker conveyor and is connected to the connecting pipe at the outlet of the waste heat boiler.

[0027] The exemplary embodiments of this application may have some or all of the following beneficial effects:

[0028] 1. In a kiln head waste heat utilization system provided in the example embodiment of this application, a portion of the gas in the intermediate temperature section of the grate cooler is introduced into the waste heat boiler to form waste heat power generation air for its use, and another portion is introduced into the coal mill system to form coal mill air for its use. This allows the kiln head waste heat utilization system to fully utilize the heat in the intermediate temperature section of the grate cooler. After the waste heat boiler discharges the used gas, the first waste heat power generation air circulation unit in the waste heat power generation air circulation unit can recirculate part of the airflow discharged from the waste heat boiler back into the grate cooler; while the coal mill circulation air unit can recirculate all the coal mill air used by the coal mill system back into the grate cooler. Specifically, the moisture carried by the coal mill air during the drying of raw coal is recovered into the grate cooler. The moisture evaporates and absorbs heat within the grate cooler, further accelerating the cooling of the clinker and thus improving the cooling efficiency of the mid-temperature section of the grate cooler. Compared to existing technologies, this method does not introduce moisture into the kiln head burner, thereby preventing heat loss within the burner. In this application, introducing the coal mill air into the grate cooler not only avoids heat loss from the kiln head burner but also improves the cooling efficiency of the grate cooler for the clinker. Therefore, the kiln head waste heat utilization system in this application achieves the effects of reducing air consumption, reducing exhaust emissions, and recovering waste heat from exhaust gases.

[0029] 2. In the waste heat recovery system provided in the example embodiment of this application, when the coal mill air is discharged from the coal mill system, it carries moisture and coal dust. When the coal mill air passes through the coal mill dust collector, the dust collector filters out most of the coal dust in the coal mill air. However, the gas discharged from the dust collector still contains a small amount of coal dust and moisture. The coal dust that is not filtered out by the dust collector mixes with the moisture to form wet coal dust. This wet coal dust will enter the medium-temperature section of the grate cooler along with the recovered coal mill air. The wet coal dust rises continuously in the medium-temperature section of the grate cooler with the airflow. During the rising process, the moisture evaporates continuously, making the coal dust gradually dry and able to absorb a large amount of heat from the clinker, thus improving the cooling effect on the clinker. Before the coal dust rises to enter the waste heat boiler and coal mill system, the temperature inside the grate cooler will cause the coal dust to burn, thereby increasing the temperature of the gas entering the waste heat boiler and coal mill system. The above structure can prevent coal dust that is not filtered out by the coal mill dust collector from being directly discharged into the atmosphere and causing environmental pollution. On the other hand, it can also use moisture to improve the cooling effect of the grate cooler on the clinker and use coal dust to raise the temperature of the gas entering the waste heat boiler and coal mill system, thereby improving the heat utilization rate.

[0030] 3. In the waste heat utilization system of the kiln head provided in the example embodiment of this application, through the second waste heat power generation air circulation unit in the waste heat power generation air circulation unit, the second waste heat power generation air circulation unit can transport part of the airflow discharged from the waste heat boiler to the pulverized coal conveying unit, and convey the pulverized coal to the kiln head burner and the decomposition furnace respectively. Compared with the prior art of using outside air to transport pulverized coal, the waste heat power generation air will have a certain amount of heat, so when it enters the kiln head burner and the decomposition furnace, it can play the role of heat recovery and utilization.

[0031] 4. In the waste heat utilization system of the kiln head provided in the example embodiment of this application, through the third waste heat power generation air circulation unit in the waste heat power generation air circulation unit, the third waste heat power generation air circulation unit can introduce part of the airflow discharged from the waste heat boiler into the kiln head burner as primary air, thereby further improving the thermal utilization rate of the system.

[0032] 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

[0033] 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.

[0034] Figure 1 A schematic diagram of the waste heat utilization system at the kiln head in this embodiment of the present application is shown.

[0035] Explanation of reference numerals in the attached figures:

[0036] 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 20. Kiln tail pulverized coal blower; 21. Pulverized coal standby blower; 22. Kiln head pulverized coal blower; 23. 24. Kiln head primary air blower; 25-36. Cooling 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

[0037] 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.

[0038] 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.

[0039] 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.

[0040] like Figure 1 As shown in the embodiments of this application, a kiln head waste heat utilization system is disclosed, including a rotary kiln 1, a grate cooler 2, a coal mill system 5, and a waste heat boiler 6.

[0041] 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.

[0042] The kiln head waste heat utilization system also includes a grate cooler air collector box 37, a coal mill circulating air unit, and a waste heat power generation air circulation unit. The kiln head waste heat utilization system eliminates the need for coal mill exhaust gas to be discharged from the coal mill chimney.

[0043] 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;

[0044] 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;

[0045] 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.

[0046] 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.

[0047] 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.

[0048] In this embodiment, the coal mill circulating air unit includes a coal mill dust collector 10, a coal mill exhaust fan 11, and a coal mill circulating air valve 37-2; 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 via connecting pipes.

[0049] In this application, when the coal mill system 5 prepares pulverized coal, the coal powder is dried using the heat energy in the grate cooler 2 to remove the moisture contained in the pulverized coal. The gas discharged from the coal mill system 5 will carry the moisture evaporated from the pulverized coal. The gas then enters the coal mill dust collector 10, which is used to collect some of the coal powder dust generated by the coal mill system 5. Because the coal mill dust collector 10 needs to allow the gas to pass through and be discharged, and the coal powder dust cannot obstruct the gas flow, the coal mill dust collector 10 can only filter out most of the coal powder in the gas, leaving a small portion that cannot be completely filtered out. In the prior art, the coal powder discharged from the coal mill dust collector 10 is directly discharged through the coal mill chimney, which not only wastes energy but also causes some environmental pollution.

[0050] In this embodiment, the gas discharged from the coal mill dust collector 10 is further discharged through the coal mill exhaust fan 11, and the exhaust end of the coal mill exhaust fan 11 is connected to the grate cooler air collector 37 through connecting pipes. 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.

[0051] 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 connecting pipes. 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 of 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] Therefore, in summary, the airflow direction in the kiln head waste heat utilization system of this application is as follows:

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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. Then, the gas is filtered by the kiln head dust collector 7. This not only filters and recovers the floating clinker, reducing clinker waste, but also protects the surrounding environment. Furthermore, it can further improve the recovery and utilization of heat.

[0074] Other embodiments of this application will readily conceive of by those skilled in the art upon consideration of the specification and practice of the embodiments thereof. 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 specification and embodiments are to be considered exemplary only, and the true scope and spirit of this application are indicated by the appended claims.

Claims

1. A kiln head waste heat utilization system, comprising a rotary kiln, a grate cooler, a coal mill system, a waste heat boiler, and a pulverized coal conveying unit, wherein the rotary kiln comprises a cylinder, a kiln head burner, and a decomposition furnace, and the grate cooler is internally divided into a medium-temperature section and a low-temperature section according to the air temperature after heat exchange between the gas and clinker. Its features are, The kiln head waste heat utilization system also includes a coal mill circulating air unit and a waste heat power generation air circulation unit. The kiln head waste heat utilization system eliminates the coal mill exhaust gas discharge from the coal mill chimney. The coal mill circulating air unit is connected between the coal mill system and the medium temperature section of the grate cooler; the coal mill circulating air unit is configured such that the gas entering the coal mill system enters the grate cooler for circulation after passing through the coal mill circulating air unit; The waste heat power generation air circulation unit includes at least a first waste heat power generation air sub-circulation unit, which is configured such that a portion of the gas entering the waste heat boiler is circulated within the grate cooler via the first waste heat power generation air sub-circulation unit.

2. The kiln head waste heat utilization system according to claim 1, characterized in that, The coal mill circulating air unit includes a coal mill dust collector, a coal mill exhaust fan, a coal mill air circulation valve, and connecting pipes. The coal mill dust collector, the coal mill exhaust fan, and the coal mill air circulation valve are sequentially connected between the coal mill system and the grate cooler through the connecting pipes.

3. The kiln head waste heat utilization system according to claim 2, characterized in that, The gas flowing through the coal mill system contains coal dust and moisture; the coal mill dust collector of the coal mill circulating air unit can filter out some of the coal dust in the gas, and the remaining coal dust enters the grate cooler for recycling after passing through the coal mill exhaust fan, the coal mill circulating air valve and corresponding connecting pipes; the moisture enters the medium temperature section of the grate cooler for heat exchange after passing through the coal mill exhaust fan, the coal mill circulating air valve and corresponding connecting pipes.

4. The kiln head waste heat utilization system according to any one of claims 1-3, characterized in that, The waste heat power generation wind circulation unit also includes a second waste heat power generation wind sub-circulation unit and a third waste heat power generation wind sub-circulation unit; The second waste heat power generation air circulation unit is configured such that a portion of the gas entering the waste heat boiler enters the pulverized coal conveying unit via the second waste heat power generation air circulation unit and then enters the rotary kiln and the decomposition furnace along with the pulverized coal. The third waste heat power generation air circulation unit is configured such that a portion of the gas entering the waste heat boiler enters the kiln head burner via the third waste heat power generation air circulation unit and is used as primary air.

5. The kiln head waste heat utilization system according to claim 4, characterized in that, The first waste heat power generation air circulation unit includes a kiln head dust collector, a kiln head exhaust fan, a waste heat power generation air circulation valve, and connecting pipes. The kiln head dust collector, the kiln head exhaust fan, and the waste heat power generation air circulation valve are sequentially connected between the outlet of the waste heat boiler and the inlet of the grate cooler through the connecting pipes.

6. The kiln head waste heat utilization system according to claim 5, characterized in that, The second waste heat power generation air circulation unit is connected between the kiln head exhaust fan and the kiln head burner; The second waste heat power generation air circulation unit includes an air intake valve, a pulverized coal conveying air intake valve, a pulverized coal conveying air distribution box, a kiln tail pulverized coal blower, a kiln head pulverized coal blower, and connecting pipes. The air intake valve is connected to the inlet of the pulverized coal conveying air distribution box. One end of the pulverized coal conveying air intake valve is connected to the outlet of the kiln head exhaust fan via a connecting pipe, and the other end is connected to the inlet of the pulverized coal conveying air distribution box. One end of the kiln tail pulverized coal blower is connected to the outlet of the pulverized coal conveying air distribution box via a connecting pipe, and the other end is connected to the decomposition furnace via a kiln tail pulverized coal scale via a connecting pipe. One end of the kiln head pulverized coal blower is connected to the outlet of the pulverized coal conveying air distribution box via a connecting pipe, and the other end is connected to the kiln head burner via a kiln head pulverized coal scale via a connecting pipe.

7. The kiln head waste heat utilization system according to claim 5 or 6, characterized in that, The third waste heat power generation air circulation unit is connected between the kiln head exhaust fan and the primary air inlet of the kiln head burner; The third waste heat power generation air circulation unit includes a kiln head primary air fan and connecting pipes. One end of the kiln head primary air fan is connected to the outlet of the kiln head exhaust fan through the connecting pipes, and the other end is connected to the primary air inlet of the kiln head burner through the connecting pipes.

8. The kiln head waste heat utilization system according to claim 7, characterized in that, It also includes a waste heat power generation exhaust system, which includes a kiln head chimney and connecting pipes, and the kiln head chimney is connected to the kiln head exhaust fan through the connecting pipes. The gas entering the waste heat boiler is distributed by the first waste heat power generation air circulation unit, the second waste heat power generation air circulation unit and the third waste heat power generation air circulation unit, and the remaining gas is discharged from the kiln head chimney.

9. The kiln head waste heat utilization system according to claim 7, characterized in that, The low-temperature section of the grate cooler has an outlet, and the low-temperature gas in the low-temperature section merges with the gas from the waste heat boiler outlet through the outlet and connecting pipes before entering the kiln head dust collector.

10. The kiln head waste heat utilization system according to claim 9, characterized in that, It also includes a clinker conveying unit, which includes a clinker conveyor, a clinker silo, and connecting pipes. After the clinker inside the grate cooler exchanges heat with the gas, the clinker falls onto the clinker conveyor and is transported by the clinker conveyor to the clinker silo for storage. The temperature of the clinker decreases during the transport process by the clinker conveyor. The connecting pipe is located above the clinker conveyor and is connected to the connecting pipe at the outlet of the waste heat boiler.

Images